------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S I N F O -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2023, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This package documents the structure of the abstract syntax tree. The Atree -- package provides a basic tree structure. Sinfo describes how this structure -- is used to represent the syntax of an Ada program. -- The grammar in the RM is followed very closely in the tree design, and is -- repeated as part of this source file. -- The tree contains not only the full syntactic representation of the -- program, but also the results of semantic analysis. In particular, the -- nodes for defining identifiers, defining character literals, and defining -- operator symbols, collectively referred to as entities, represent what -- would normally be regarded as the symbol table information. In addition a -- number of the tree nodes contain semantic information. -- See the spec of Gen_IL.Gen for instructions on making changes to this file. -- Note that the official definition of what nodes have what fields is in -- Gen_IL.Gen.Gen_Nodes; if there is a discrepancy between that and the -- comments here, Gen_IL.Gen.Gen_Nodes wins. pragma Warnings (Off); -- with/use clauses for children with Namet; use Namet; with Types; use Types; with Uintp; use Uintp; with Urealp; use Urealp; pragma Warnings (On); package Sinfo is ---------------------------------------- -- Definitions of fields in tree node -- ---------------------------------------- -- The following fields are common to all nodes: -- Nkind Indicates the kind of the node. This field is present -- in all nodes. -- Sloc Location (Source_Ptr) of the corresponding token -- in the Source buffer. The individual node definitions -- show which token is referenced by this pointer. -- In_List A flag used to indicate if the node is a member -- of a node list (see package Nlists). -- Rewrite_Ins A flag set if a node is marked as a rewrite inserted -- node as a result of a call to Mark_Rewrite_Insertion. -- Small_Paren_Count -- A 2-bit count used in subexpression nodes to indicate -- the level of parentheses. The settings are 0,1,2 and -- 3 for many. If the value is 3, then an auxiliary table -- is used to indicate the real value, which is computed by -- Paren_Count. Set to zero for nonsubexpression nodes. -- Note: the required parentheses surrounding conditional -- and quantified expressions count as a level of parens -- for this purpose, so e.g. in X := (if A then B else C); -- Paren_Count for the right side will be 1. -- Comes_From_Source -- This flag is present in all nodes. It is set if the -- node is built by the scanner or parser, and clear if -- the node is built by the analyzer or expander. It -- indicates that the node corresponds to a construct -- that appears in the original source program. -- Analyzed This flag is present in all nodes. It is set when -- a node is analyzed, and is used to avoid analyzing -- the same node twice. Analysis includes expansion if -- expansion is active, so in this case if the flag is -- set it means the node has been analyzed and expanded. -- Error_Posted This flag is present in all nodes. It is set when -- an error message is posted which is associated with -- the flagged node. This is used to avoid posting more -- than one message on the same node. -- Link For a node, points to the Parent. For a list, points -- to the list header. Note that in the latter case, a -- client cannot modify the link field. This field is -- private to the Atree package (but is also modified -- by the Nlists package). -- The following additional fields are common to all entities (that is, -- nodes whose Nkind is in N_Entity): -- Ekind Entity type. -- Convention Entity convention (Convention_Id value) -------------------------------- -- Implicit Nodes in the Tree -- -------------------------------- -- Generally the structure of the tree very closely follows the grammar as -- defined in the RM. However, certain nodes are omitted to save space and -- simplify semantic processing. Two general classes of such omitted nodes -- are as follows: -- If the only possibilities for a non-terminal are one or more other -- non-terminals (i.e. the rule is a "skinny" rule), then usually the -- corresponding node is omitted from the tree, and the target construct -- appears directly. For example, a real type definition is either -- floating point definition or a fixed point definition. No explicit node -- appears for real type definition. Instead either the floating point -- definition or fixed point definition appears directly. -- If a non-terminal corresponds to a list of some other non-terminal -- (possibly with separating punctuation), then usually it is omitted from -- the tree, and a list of components appears instead. For example, -- sequence of statements does not appear explicitly in the tree. Instead -- a list of statements appears directly. -- Some additional cases of omitted nodes occur and are documented -- individually. In particular, many nodes are omitted in the tree -- generated for an expression. ------------------------------------------- -- Handling of Defining Identifier Lists -- ------------------------------------------- -- In several declarative forms in the syntax, lists of defining -- identifiers appear (object declarations, component declarations, number -- declarations etc.) -- The semantics of such statements are equivalent to a series of identical -- declarations of single defining identifiers (except that conformance -- checks require the same grouping of identifiers in the parameter case). -- To simplify semantic processing, the parser breaks down such multiple -- declaration cases into sequences of single declarations, duplicating -- type and initialization information as required. The flags More_Ids and -- Prev_Ids are used to record the original form of the source in the case -- where the original source used a list of names, More_Ids being set on -- all but the last name and Prev_Ids being set on all but the first name. -- These flags are used to reconstruct the original source (e.g. in the -- Sprint package), and also are included in the conformance checks, but -- otherwise have no semantic significance. -- Note: the reason that we use More_Ids and Prev_Ids rather than -- First_Name and Last_Name flags is so that the flags are off in the -- normal one identifier case, which minimizes tree print output. ----------------------- -- Use of Node Lists -- ----------------------- -- With a few exceptions, if a construction of the form {non-terminal} -- appears in the tree, lists are used in the corresponding tree node (see -- package Nlists for handling of node lists). In this case a field of the -- parent node points to a list of nodes for the non-terminal. The field -- name for such fields has a plural name which always ends in "s". For -- example, a case statement has a field Alternatives pointing to list of -- case statement alternative nodes. -- Only fields pointing to lists have names ending in "s", so generally the -- structure is strongly typed, fields not ending in s point to single -- nodes, and fields ending in s point to lists. -- The following example shows how a traversal of a list is written. We -- suppose here that Stmt points to a N_Case_Statement node which has a -- list field called Alternatives: -- Alt := First (Alternatives (Stmt)); -- while Present (Alt) loop -- .. -- -- processing for case statement alternative Alt -- .. -- Alt := Next (Alt); -- end loop; -- The Present function tests for Empty, which in this case signals the end -- of the list. First returns Empty immediately if the list is empty. -- Present is defined in Atree; First and Next are defined in Nlists. -- The exceptions to this rule occur with {DEFINING_IDENTIFIERS} in all -- contexts, which is handled as described in the previous section, and -- with {,library_unit_NAME} in the N_With_Clause node, which is handled -- using the First_Name and Last_Name flags, as further detailed in the -- description of the N_With_Clause node. ------------- -- Pragmas -- ------------- -- Pragmas can appear in many different context, but are not included in -- the grammar. Still they must appear in the tree, so they can be properly -- processed. -- Two approaches are used. In some cases, an extra field is defined in an -- appropriate node that contains a list of pragmas appearing in the -- expected context. For example pragmas can appear before an -- Accept_Alternative in a Selective_Accept_Statement, and these pragmas -- appear in the Pragmas_Before field of the N_Accept_Alternative node. -- The other approach is to simply allow pragmas to appear in syntactic -- lists where the grammar (of course) does not include the possibility. -- For example, the Variants field of an N_Variant_Part node points to a -- list that can contain both N_Pragma and N_Variant nodes. -- To make processing easier in the latter case, the Nlists package -- provides a set of routines (First_Non_Pragma, Last_Non_Pragma, -- Next_Non_Pragma, Prev_Non_Pragma) that allow such lists to be handled -- ignoring all pragmas. -- In the case of the variants list, we can either write: -- Variant := First (Variants (N)); -- while Present (Variant) loop -- ... -- Variant := Next (Variant); -- end loop; -- or -- Variant := First_Non_Pragma (Variants (N)); -- while Present (Variant) loop -- ... -- Variant := Next_Non_Pragma (Variant); -- end loop; -- In the first form of the loop, Variant can either be an N_Pragma or an -- N_Variant node. In the second form, Variant can only be N_Variant since -- all pragmas are skipped. --------------------- -- Optional Fields -- --------------------- -- Fields which correspond to a section of the syntax enclosed in square -- brackets are generally omitted (and the corresponding field set to Empty -- for a node, or No_List for a list). The documentation of such fields -- notes these cases. One exception to this rule occurs in the case of -- possibly empty statement sequences (such as the sequence of statements -- in an entry call alternative). Such cases appear in the syntax rules as -- [SEQUENCE_OF_STATEMENTS] and the fields corresponding to such optional -- statement sequences always contain an empty list (not No_List) if no -- statements are present. -- Note: the utility program that constructs the body and spec of the Nmake -- package relies on the format of the comments to determine if a field -- should have a default value in the corresponding make routine. The rule -- is that if the first line of the description of the field contains the -- string "(set to xxx if", then a default value of xxx is provided for -- this field in the corresponding Make_yyy routine. ----------------------------------- -- Note on Body/Spec Terminology -- ----------------------------------- -- In informal discussions about Ada, it is customary to refer to package -- and subprogram specs and bodies. However, this is not technically -- correct, what is normally referred to as a spec or specification is in -- fact a package declaration or subprogram declaration. We are careful in -- GNAT to use the correct terminology and in particular, the full word -- specification is never used as an incorrect substitute for declaration. -- The structure and terminology used in the tree also reflects the grammar -- and thus uses declaration and specification in the technically correct -- manner. -- However, there are contexts in which the informal terminology is useful. -- We have the word "body" to refer to the Interp_Etype declared by the -- declaration of a unit body, and in some contexts we need similar term to -- refer to the entity declared by the package or subprogram declaration, -- and simply using declaration can be confusing since the body also has a -- declaration. -- An example of such a context is the link between the package body and -- its declaration. With_Declaration is confusing, since the package body -- itself is a declaration. -- To deal with this problem, we reserve the informal term Spec, i.e. the -- popular abbreviation used in this context, to refer to the entity -- declared by the package or subprogram declaration. So in the above -- example case, the field in the body is called With_Spec. -- Another important context for the use of the word Spec is in error -- messages, where a hyper-correct use of declaration would be confusing to -- a typical Ada programmer, and even for an expert programmer can cause -- confusion since the body has a declaration as well. -- So, to summarize: -- Declaration always refers to the syntactic entity that is called -- a declaration. In particular, subprogram declaration -- and package declaration are used to describe the -- syntactic entity that includes the semicolon. -- Specification always refers to the syntactic entity that is called -- a specification. In particular, the terms procedure -- specification, function specification, package -- specification, subprogram specification always refer -- to the syntactic entity that has no semicolon. -- Spec is an informal term, used to refer to the entity -- that is declared by a task declaration, protected -- declaration, generic declaration, subprogram -- declaration or package declaration. -- This convention is followed throughout the GNAT documentation -- both internal and external, and in all error message text. ------------------------ -- Internal Use Nodes -- ------------------------ -- These are Node_Kind settings used in the internal implementation which -- are not logically part of the specification. -- N_Unused_At_Start -- Completely unused entry at the start of the enumeration type. This -- is inserted so that no legitimate value is zero, which helps to get -- better debugging behavior, since zero is a likely uninitialized value). -- N_Unused_At_End -- Completely unused entry at the end of the enumeration type. This is -- handy so that arrays with Node_Kind as the index type have an extra -- entry at the end (see for example the use of the Pchar_Pos_Array in -- Treepr, where the extra entry provides the limit value when dealing with -- the last used entry in the array). ----------------------------------------- -- Note on the settings of Sloc fields -- ----------------------------------------- -- The Sloc field of nodes that come from the source is set by the parser. -- For internal nodes, and nodes generated during expansion the Sloc is -- usually set in the call to the constructor for the node. In general the -- Sloc value chosen for an internal node is the Sloc of the source node -- whose processing is responsible for the expansion. For example, the Sloc -- of an inherited primitive operation is the Sloc of the corresponding -- derived type declaration. -- For the nodes of a generic instantiation, the Sloc value is encoded to -- represent both the original Sloc in the generic unit, and the Sloc of -- the instantiation itself. See Sinput.ads for details. -- Subprogram instances create two callable entities: one is the visible -- subprogram instance, and the other is an anonymous subprogram nested -- within a wrapper package that contains the renamings for the actuals. -- Both of these entities have the Sloc of the defining entity in the -- instantiation node. This simplified for instance in the past some ASIS -- queries. ----------------------- -- Field Definitions -- ----------------------- -- In the following node definitions, all fields, both syntactic and -- semantic, are documented. The one exception is in the case of entities -- (defining identifiers, character literals, and operator symbols), where -- the usage of the fields depends on the entity kind. Entity fields are -- fully documented in the separate package Einfo. -- In the node definitions, three common sets of fields are abbreviated to -- save both space in the documentation, and also space in the string -- (defined in Tree_Print_Strings) used to print trees. The following -- abbreviations are used: -- "plus fields for binary operator" -- Chars Name_Id for the operator -- Left_Opnd left operand expression -- Right_Opnd right operand expression -- Entity defining entity for operator -- Associated_Node for generic processing -- Do_Overflow_Check set if overflow check needed -- Has_Private_View set in generic units -- Has_Secondary_Private_View set in generic units -- "plus fields for unary operator" -- Chars Name_Id for the operator -- Right_Opnd right operand expression -- Entity defining entity for operator -- Associated_Node for generic processing -- Do_Overflow_Check set if overflow check needed -- Has_Private_View set in generic units -- Has_Secondary_Private_View set in generic units -- "plus fields for expression" -- Paren_Count number of parentheses levels -- Etype type of the expression -- Is_Overloaded >1 type interpretation exists -- Is_Static_Expression set for static expression -- Raises_Constraint_Error evaluation raises CE -- Must_Not_Freeze set if must not freeze -- Do_Range_Check set if a range check needed -- Has_Dynamic_Length_Check set if length check inserted -- Assignment_OK set if modification is OK -- Is_Controlling_Actual set for controlling argument -- Note: see under (EXPRESSION) for further details on the use of -- the Paren_Count field to record the number of parentheses levels. -- Node_Kind is the type used in the Nkind field to indicate the node kind. -- The actual definition of this type is given later (the reason for this -- is that we want the descriptions ordered by logical chapter in the RM, -- but the type definition is reordered to facilitate the definition of -- some subtype ranges. The individual descriptions of the nodes show how -- the various fields are used in each node kind, as well as providing -- logical names for the fields. Functions and procedures are provided for -- accessing and setting these fields using these logical names. ----------------------- -- Gigi Restrictions -- ----------------------- -- The tree passed to Gigi is more restricted than the general tree form. -- For example, as a result of expansion, most of the tasking nodes can -- never appear. For each node to which either a complete or partial -- restriction applies, a note entitled "Gigi restriction" appears which -- documents the restriction. -- Note that most of these restrictions apply only to trees generated when -- code is being generated, since they involve expander actions that -- destroy the tree. ---------------- -- Ghost Mode -- ---------------- -- The SPARK RM 6.9 defines two classes of constructs - Ghost entities and -- Ghost statements. The intent of the feature is to treat Ghost constructs -- as non-existent when Ghost assertion policy Ignore is in effect. -- -- The corresponding nodes which map to Ghost constructs are: -- -- Ghost entities -- Declaration nodes -- N_Package_Body -- N_Subprogram_Body -- -- Ghost statements -- N_Assignment_Statement -- N_Procedure_Call_Statement -- N_Pragma -- -- In addition, the compiler treats instantiations as Ghost entities -- -- To achieve the removal of ignored Ghost constructs, the compiler relies -- on global variables Ghost_Mode and Ignored_Ghost_Region, which comprise -- a mechanism called "Ghost regions". -- -- The values of Ghost_Mode are as follows: -- -- 1. Check - All static semantics as defined in SPARK RM 6.9 are in -- effect. The Ghost region has mode Check. -- -- 2. Ignore - Same as Check, ignored Ghost code is not present in ALI -- files, object files, and the final executable. The Ghost region -- has mode Ignore. -- -- 3. None - No Ghost region is in effect -- -- The value of Ignored_Ghost_Region captures the node which initiates an -- ignored Ghost region. -- -- A Ghost region is a compiler operating mode, similar to Check_Syntax, -- however a region is much more finely grained and depends on the policy -- in effect. The region starts prior to the analysis of a Ghost construct -- and ends immediately after its expansion. The region is established as -- follows: -- -- 1. Declarations - Prior to analysis, if the declaration is subject to -- pragma Ghost. -- -- 2. Renaming declarations - Same as 1) or when the renamed entity is -- Ghost. -- -- 3. Completing declarations - Same as 1) or when the declaration is -- partially analyzed and the declaration completes a Ghost entity. -- -- 4. N_Package_Body, N_Subprogram_Body - Same as 1) or when the body is -- partially analyzed and completes a Ghost entity. -- -- 5. N_Assignment_Statement - After the left hand side is analyzed and -- references a Ghost entity. -- -- 6. N_Procedure_Call_Statement - After the name is analyzed and denotes -- a Ghost procedure. -- -- 7. N_Pragma - During analysis, when the related entity is Ghost or the -- pragma encloses a Ghost entity. -- -- 8. Instantiations - Save as 1) or when the instantiation is partially -- analyzed and the generic template is Ghost. -- -- The following routines install a new Ghost region: -- -- Install_Ghost_Region -- Mark_And_Set_Ghost_xxx -- Set_Ghost_Mode -- -- The following routine ends a Ghost region: -- -- Restore_Ghost_Region -- -- A region may be reinstalled similarly to scopes for decoupled expansion -- such as the generation of dispatch tables or the creation of a predicate -- function. -- -- If the mode of a Ghost region is Ignore, any newly created nodes as well -- as source entities are marked as ignored Ghost. In addition, the marking -- process signals all enclosing scopes that an ignored Ghost node resides -- within. The compilation unit where the node resides is also added to an -- auxiliary table for post processing. -- -- After the analysis and expansion of all compilation units takes place -- as well as the instantiation of all inlined [generic] bodies, the GNAT -- driver initiates a separate pass which removes all ignored Ghost nodes -- from all units stored in the auxiliary table. -------------------- -- GNATprove Mode -- -------------------- -- When a file is compiled in GNATprove mode (-gnatd.F), a very light -- expansion is performed and the analysis must generate a tree in a -- form that meets additional requirements. -- This light expansion does two transformations of the tree that cannot -- be postponed till after semantic analysis: -- 1. Replace object renamings by renamed object. This requires the -- introduction of temporaries at the point of the renaming, which -- must be properly analyzed. -- 2. Fully qualify entity names. This is needed to generate suitable -- local effects and call-graphs in ALI files, with the completely -- qualified names (in particular the suffix to distinguish homonyms). -- The tree after this light expansion should be fully analyzed -- semantically, which sometimes requires the insertion of semantic -- preanalysis, for example for subprogram contracts and pragma -- check/assert. In particular, all expressions must have their proper -- type, and semantic links should be set between tree nodes (partial to -- full view, etc.). Some kinds of nodes should be either absent, or can be -- ignored by the formal verification backend: -- N_Object_Renaming_Declaration: can be ignored safely -- N_Expression_Function: absent (rewritten) -- N_Expression_With_Actions: absent (not generated) -- SPARK cross-references are generated from the regular cross-references -- (used for browsing and code understanding) and additional references -- collected during semantic analysis, in particular on all dereferences. -- These SPARK cross-references are output in a separate section of ALI -- files, as described in spark_xrefs.adb. They are the basis for the -- computation of data dependences in GNATprove. This implies that all -- cross-references should be generated in this mode, even those that would -- not make sense from a user point-of-view, and that cross-references that -- do not lead to data dependences for subprograms can be safely ignored. -- GNATprove relies on the following front end behaviors: -- 1. The first declarations in the list of visible declarations of -- a package declaration for a generic instance, up to the first -- declaration which comes from source, should correspond to -- the "mappings nodes" between formal and actual generic parameters. -- 2. In addition pragma Debug statements are removed from the tree -- (rewritten to NULL stmt), since they should be ignored in formal -- verification. -- 3. An error is also issued for missing subunits, similar to the -- warning issued when generating code, to avoid formal verification -- of a partial unit. -- 4. Unconstrained types are not replaced by constrained types whose -- bounds are generated from an expression: Expand_Subtype_From_Expr -- should be a no-op. -- 5. Errors (instead of warnings) are issued on compile-time-known -- constraint errors even though such cases do not correspond to -- illegalities in the Ada RM (this is simply another case where -- GNATprove implements a subset of the full language). -- -- However, there are a few exceptions to this rule for cases where -- we want to allow the GNATprove analysis to proceed (e.g. range -- checks on empty ranges, which typically appear in deactivated -- code in a particular configuration). -- 6. Subtypes should match in the AST, even after a generic is -- instantiated. In particular, GNATprove relies on the fact that, -- on a selected component, the type of the selected component is -- the type of the corresponding component in the prefix of the -- selected component. -- -- Note that, in some cases, we know that this rule is broken by the -- frontend. In particular, if the selected component is a packed -- array depending on a discriminant of a unconstrained formal object -- parameter of a generic. ---------------- -- SPARK Mode -- ---------------- -- The SPARK RM 1.6.5 defines a mode of operation called "SPARK mode" which -- starts a scope where the SPARK language semantics are either On, Off, or -- Auto, where Auto leaves the choice to the tools. A SPARK mode may be -- specified by means of an aspect or a pragma. -- The following entities may be subject to a SPARK mode. Entities marked -- with * may possess two different SPARK modes. -- E_Entry -- E_Entry_Family -- E_Function -- E_Generic_Function -- E_Generic_Package * -- E_Generic_Procedure -- E_Operator -- E_Package * -- E_Package_Body * -- E_Procedure -- E_Protected_Body -- E_Protected_Subtype -- E_Protected_Type * -- E_Subprogram_Body -- E_Task_Body -- E_Task_Subtype -- E_Task_Type * -- E_Variable -- In order to manage SPARK scopes, the compiler relies on global variables -- SPARK_Mode and SPARK_Mode_Pragma and a mechanism called "SPARK regions." -- Routines Install_SPARK_Mode and Set_SPARK_Mode create a new SPARK region -- and routine Restore_SPARK_Mode ends a SPARK region. A region may be -- reinstalled similarly to scopes. ----------------------- -- Check Flag Fields -- ----------------------- -- The following flag fields appear in expression nodes: -- Do_Division_Check -- Do_Overflow_Check -- Do_Range_Check -- These three flags are always set by the front end during semantic -- analysis, on expression nodes that may trigger the corresponding -- check. The front end then inserts or not the check during expansion. In -- particular, these flags should also be correctly set in GNATprove mode. -- As a special case, the front end does not insert a Do_Division_Check -- flag on float exponentiation expressions, for the case where the value -- is 0.0 and the exponent is negative, although this case does lead to a -- division check failure. As another special case, the front end does not -- insert a Do_Range_Check on an allocator where the designated type is -- scalar, and the designated type is more constrained than the type of the -- initialized allocator value or the type of the default value for an -- uninitialized allocator. -- Note that the expander always takes care of the Do_Range_Check case, so -- this flag will never be set in the expanded tree passed to the back end. -- For the other two flags, the check can be generated either by the back -- end or by the front end, depending on the setting of a target parameter. -- Note that this accounts for all nodes that trigger the corresponding -- checks, except for range checks on subtype_indications, which may be -- required to check that a range_constraint is compatible with the given -- subtype (RM 3.2.2(11)). -- The following flag fields appear in various nodes: -- Do_Discriminant_Check -- Do_Length_Check -- Do_Storage_Check -- These flags are used in some specific cases by the front end, either -- during semantic analysis or during expansion, and cannot be expected -- to be set on all nodes that trigger the corresponding check. ------------------------ -- Common Flag Fields -- ------------------------ -- The following flag fields appear in all nodes: -- Analyzed -- This flag is used to indicate that a node (and all its children) have -- been analyzed. It is used to avoid reanalysis of a node that has -- already been analyzed, both for efficiency and functional correctness -- reasons. -- Comes_From_Source -- This flag is set if the node comes directly from an explicit construct -- in the source. It is normally on for any nodes built by the scanner or -- parser from the source program, with the exception that in a few cases -- the parser adds nodes to normalize the representation (in particular, -- a null statement is added to a package body if there is no begin/end -- initialization section). -- -- Most nodes inserted by the analyzer or expander are not considered -- as coming from source, so the flag is off for such nodes. In a few -- cases, the expander constructs nodes closely equivalent to nodes -- from the source program (e.g. the allocator built for build-in-place -- case), and the Comes_From_Source flag is deliberately set. -- Error_Posted -- This flag is used to avoid multiple error messages being posted on or -- referring to the same node. This flag is set if an error message -- refers to a node or is posted on its source location, and has the -- effect of inhibiting further messages involving this same node. ----------------------- -- Modify_Tree_For_C -- ----------------------- -- If the flag Opt.Modify_Tree_For_C is set True, then the tree is modified -- in ways that help match the semantics better with C, easing the task of -- interfacing to C code generators (other than GCC, where the work is done -- in gigi, and there is no point in changing that), and also making life -- easier for Cprint in generating C source code. -- The current modifications implemented are as follows: -- N_Op_Rotate_Left, N_Op_Rotate_Right, N_Shift_Right_Arithmetic nodes -- are eliminated from the tree (since these operations do not exist in -- C), and the operations are rewritten in terms of logical shifts and -- other logical operations that do exist in C. See Exp_Ch4 expansion -- routines for these operators for details of the transformations made. -- The right operand of N_Op_Shift_Right and N_Op_Shift_Left is always -- less than the word size (since other values are not well-defined in -- C). This is done using an explicit test if necessary. -- Min and Max attributes are expanded into equivalent if expressions, -- dealing properly with side effect issues. -- Mod for signed integer types is expanded into equivalent expressions -- using Rem (which is % in C) and other C-available operators. -- Functions returning bounded arrays are transformed into procedures -- with an extra out parameter, and the calls updated accordingly. -- Aggregates are only kept unexpanded for object declarations, otherwise -- they are systematically expanded into loops (for arrays) and -- individual assignments (for records). -- Unconstrained array types are handled by means of fat pointers. -- Postconditions are inlined by the frontend since their body may have -- references to itypes defined in the enclosing subprogram. ------------------------------------ -- Description of Semantic Fields -- ------------------------------------ -- The meaning of the syntactic fields is generally clear from their names -- without any further description, since the names are chosen to -- correspond very closely to the syntax in the reference manual. This -- section describes the usage of the semantic fields, which are used to -- contain additional information determined during semantic analysis. -- Accept_Handler_Records -- This field is present only in an N_Accept_Alternative node. It is used -- to temporarily hold the exception handler records from an accept -- statement in a selective accept. These exception handlers will -- eventually be placed in the Handler_Records list of the procedure -- built for this accept (see Expand_N_Selective_Accept procedure in -- Exp_Ch9 for further details). -- Access_Types_To_Process -- Present in N_Freeze_Entity nodes for Incomplete or private types. -- Contains the list of access types which may require specific treatment -- when the nature of the type completion is completely known. An example -- of such treatment is the generation of the associated_final_chain. -- Actions -- This field contains a sequence of actions that are associated with the -- node holding the field. See the individual node types for details of -- how this field is used, as well as the description of the specific use -- for a particular node type. -- Activation_Chain_Entity -- This is used in tree nodes representing task activators (blocks, -- subprogram bodies, package declarations, and task bodies). It is -- initially Empty, and then gets set to point to the entity for the -- declared Activation_Chain variable when the first task is declared. -- When tasks are declared in the corresponding declarative region this -- entity is located by name (its name is always _Chain) and the declared -- tasks are added to the chain. Note that N_Extended_Return_Statement -- does not have this attribute, although it does have an activation -- chain. This chain is used to store the tasks temporarily, and is not -- used for activating them. On successful completion of the return -- statement, the tasks are moved to the caller's chain, and the caller -- activates them. -- Acts_As_Spec -- A flag set in the N_Subprogram_Body node for a subprogram body which -- is acting as its own spec. In the case of a library-level subprogram -- the flag is set as well on the parent compilation unit node. -- Actual_Designated_Subtype -- Present in N_Free_Statement and N_Explicit_Dereference nodes. If gigi -- needs to know the dynamic constrained subtype of the designated -- object, this attribute is set to that subtype. This is done for -- N_Free_Statements for access-to-classwide types and access-to- -- unconstrained packed array types. For N_Explicit_Dereference, -- this is done in two circumstances: 1) when the designated type is -- an unconstrained packed array and the dereference is the prefix of -- a 'Size attribute reference, or 2) when the dereference node is -- created for the expansion of an allocator with a subtype_indication -- and the designated subtype is an unconstrained composite type. -- Address_Warning_Posted -- Present in N_Attribute_Definition nodes. Set to indicate that we have -- posted a warning for the address clause regarding size or alignment -- issues. Used to inhibit multiple redundant messages. -- Aggregate_Bounds -- Present in array N_Aggregate nodes. If the bounds of the aggregate are -- known at compile time, this field points to an N_Range node with those -- bounds. Otherwise Empty. -- All_Others -- Present in an N_Others_Choice node. This flag is set for an others -- exception where all exceptions are to be caught, even those that are -- not normally handled (in particular the tasking abort signal). This -- is used for translation of the at end handler into a normal exception -- handler. -- Aspect_On_Partial_View -- Present on an N_Aspect_Specification node. For an aspect that applies -- to a type entity, indicates whether the specification appears on the -- partial view of a private type or extension. Undefined for aspects -- that apply to other entities. -- Aspect_Rep_Item -- Present in N_Aspect_Specification nodes. Points to the corresponding -- pragma/attribute definition node used to process the aspect. -- Assignment_OK -- This flag is set in a subexpression node for an object, indicating -- that the associated object can be modified, even if this would not -- normally be permissible (either by direct assignment, or by being -- passed as an out or in-out parameter). This is used by the expander -- for a number of purposes, including initialization of constants and -- limited type objects (such as tasks), setting discriminant fields, -- setting tag values, etc. N_Object_Declaration nodes also have this -- flag defined. Here it is used to indicate that an initialization -- expression is valid, even where it would normally not be allowed -- (e.g. where the type involved is limited). It is also used to stop -- a Force_Evaluation call for an unchecked conversion, but this usage -- is unclear and not documented ??? -- Associated_Node -- Present in nodes that can denote an entity: identifiers, character -- literals, operator symbols, expanded names, operator nodes, and -- attribute reference nodes (all these nodes have an Entity field). -- This field is also present in N_Aggregate, N_Selected_Component, and -- N_Extension_Aggregate nodes. This field is used in generic processing -- to create links between the generic template and the generic copy. -- See Sem_Ch12.Get_Associated_Node for full details. Note that this -- field overlaps Entity, which is fine, since, as explained in Sem_Ch12, -- the normal function of Entity is not required at the point where the -- Associated_Node is set. Note also, that in generic templates, this -- means that the Entity field does not necessarily point to an Entity. -- Since the back end is expected to ignore generic templates, this is -- harmless. -- Atomic_Sync_Required -- This flag is set on a node for which atomic synchronization is -- required for the corresponding reference or modification. -- At_End_Proc -- This field is present in N_Handled_Sequence_Of_Statements, -- N_Package_Body, N_Subprogram_Body, N_Task_Body, N_Block_Statement, -- and N_Entry_Body. -- It contains an identifier reference for the cleanup procedure to be -- called. See description of N_Handled_Sequence_Of_Statements node -- for further details. -- Backwards_OK -- A flag present in the N_Assignment_Statement node. It is used only -- if the type being assigned is an array type, and is set if analysis -- determines that it is definitely safe to do the copy backwards, i.e. -- starting at the highest addressed element. This is the case if either -- the operands do not overlap, or they may overlap, but if they do, -- then the left operand is at a higher address than the right operand. -- -- Note: If neither of the flags Forwards_OK or Backwards_OK is set, it -- means that the front end could not determine that either direction is -- definitely safe, and a runtime check may be required if the backend -- cannot figure it out. If both flags Forwards_OK and Backwards_OK are -- set, it means that the front end can assure no overlap of operands. -- Body_To_Inline -- Present in subprogram declarations. Denotes analyzed but unexpanded -- body of subprogram, to be used when inlining calls. Present when the -- subprogram has an Inline pragma and inlining is enabled. If the -- declaration is completed by a renaming_as_body, and the renamed entity -- is a subprogram, the Body_To_Inline is the name of that entity, which -- is used directly in later calls to the original subprogram. -- Body_Required -- A flag that appears in the N_Compilation_Unit node indicating that -- the corresponding unit requires a body. For the package case, this -- indicates that a completion is required. In Ada 95, if the flag is not -- set for the package case, then a body may not be present. In Ada 83, -- if the flag is not set for the package case, then body is optional. -- For a subprogram declaration, the flag is set except in the case where -- a pragma Import or Interface applies, in which case no body is -- permitted (in Ada 83 or Ada 95). -- Cannot_Be_Superflat -- This flag is present in N_Range nodes. It is set if the range is of a -- discrete type and cannot be superflat, i.e. it is guaranteed that the -- inequality High_Bound >= Low_Bound - 1 is true. At the time of this -- writing, it is only used by the code generator to streamline things. -- Cleanup_Actions -- Present in block statements created for transient blocks, contains -- additional cleanup actions carried over from the transient scope. -- Check_Address_Alignment -- A flag present in N_Attribute_Definition clause for a 'Address -- attribute definition. This flag is set if a dynamic check should be -- generated at the freeze point for the entity to which this address -- clause applies. The reason that we need this flag is that we want to -- check for range checks being suppressed at the point where the -- attribute definition clause is given, rather than testing this at the -- freeze point. -- Comes_From_Check_Or_Contract -- This flag is present in all N_If_Statement nodes and -- gets set when an N_If_Statement is generated as part of -- the expansion of a Check, Assert, or contract-related -- pragma. -- Comes_From_Extended_Return_Statement -- Present in N_Simple_Return_Statement nodes. True if this node was -- constructed as part of the N_Extended_Return_Statement expansion. -- Comes_From_Iterator -- Present in N_Object_Renaming_Declaration nodes. True if this node was -- was constructed as part of the expansion of an iterator -- specification. -- Compare_Type -- Present in N_Op_Compare nodes. Set during resolution to the type of -- the operands. It is used to propagate the type of the operands from -- a N_Op_Compare node in a generic construct to the nodes created from -- it in the various instances, when this type is global to the generic -- construct. Resolution for global types cannot be redone in instances -- because the instantiation can be done out of context, e.g. for bodies, -- and the visibility of global types is incorrect in this case; that is -- why the result of the resolution done in the generic construct needs -- to be available in the instances but, unlike for arithmetic operators, -- the Etype cannot be used to that effect for comparison operators. It -- is also used as the type subject to the Has_Private_View processing on -- the nodes instead of the Etype. -- Compile_Time_Known_Aggregate -- Present in N_Aggregate nodes. Set for aggregates which can be fully -- evaluated at compile time without raising constraint error. Such -- aggregates can be passed as is to the back end without any expansion. -- See Exp_Aggr for specific conditions under which this flag gets set. -- Componentwise_Assignment -- Present in N_Assignment_Statement nodes. Set for a record assignment -- where all that needs doing is to expand it into component-by-component -- assignments. This is used internally for the case of tagged types with -- rep clauses, where we need to avoid recursion (we don't want to try to -- generate a call to the primitive operation, because this is the case -- where we are compiling the primitive operation). Note that when we are -- expanding component assignments in this case, we never assign the _tag -- field, but we recursively assign components of the parent type. -- Condition_Actions -- This field appears in else-if nodes and in the iteration scheme node -- for while loops. This field is only used during semantic processing to -- temporarily hold actions inserted into the tree. In the tree passed -- to gigi, the condition actions field is always set to No_List. For -- details on how this field is used, see the routine Insert_Actions in -- package Exp_Util, and also the expansion routines for the relevant -- nodes. -- Context_Pending -- This field appears in Compilation_Unit nodes, to indicate that the -- context of the unit is being compiled. Used to detect circularities -- that are not otherwise detected by the loading mechanism. Such -- circularities can occur in the presence of limited and non-limited -- with_clauses that mention the same units. -- Controlling_Argument -- This field is set in procedure and function call nodes if the call -- is a dispatching call (it is Empty for a non-dispatching call). It -- indicates the source of the call's controlling tag. For procedure -- calls, the Controlling_Argument is one of the actuals. For function -- that has a dispatching result, it is an entity in the context of the -- call that can provide a tag, or else it is the tag of the root type -- of the class. It can also specify a tag directly rather than being a -- tagged object. The latter is needed by the implementations of AI-239 -- and AI-260. -- Conversion_OK -- A flag set on type conversion nodes to indicate that the conversion -- is to be considered as being valid, even though it is the case that -- the conversion is not valid Ada. This is used for attributes Enum_Rep, -- Pos, Val, Fixed_Value and Integer_Value, for internal conversions done -- for fixed-point operations, and for certain conversions for calls to -- initialization procedures. If Conversion_OK is set, then Etype must be -- set (the analyzer assumes that Etype has been set). For the case of -- fixed-point operands, it also indicates that the conversion is to be -- direct conversion of the underlying integer result, with no regard to -- the small operand. -- Corresponding_Aspect -- Present in N_Pragma node. Used to point back to the source aspect from -- the corresponding pragma. This field is Empty for source pragmas. -- Corresponding_Body -- This field is set in subprogram declarations, package declarations, -- entry declarations of protected types, and in generic units. It points -- to the defining entity for the corresponding body (NOT the node for -- the body itself). -- Corresponding_Entry_Body -- Defined in N_Subprogram_Body. Set for subprogram bodies that implement -- a protected type entry; points to the body for the entry. -- Corresponding_Formal_Spec -- This field is set in subprogram renaming declarations, where it points -- to the defining entity for a formal subprogram in the case where the -- renaming corresponds to a generic formal subprogram association in an -- instantiation. The field is Empty if the renaming does not correspond -- to such a formal association. -- Corresponding_Generic_Association -- This field is defined for object declarations and object renaming -- declarations. It is set for the declarations within an instance that -- map generic formals to their actuals. If set, the field points either -- to a copy of a default expression for an actual of mode IN or to a -- generic_association which is the original parent of the expression or -- name appearing in the declaration. This simplifies GNATprove queries. -- Corresponding_Integer_Value -- This field is set in real literals of fixed-point types (it is not -- used for floating-point types). It contains the integer value used -- to represent the fixed-point value. It is also set on the universal -- real literals used to represent bounds of fixed-point base types -- and their first named subtypes. -- Corresponding_Spec -- This field is set in subprogram, package, task, entry and protected -- body nodes where it points to the defining entity in the corresponding -- spec. The attribute is also set in N_With_Clause nodes where it points -- to the defining entity for the with'ed spec, and in a subprogram -- renaming declaration when it is a Renaming_As_Body. The field is Empty -- if there is no corresponding spec, as in the case of a subprogram body -- that serves as its own spec. -- -- In Ada 2012, Corresponding_Spec is set on expression functions that -- complete a subprogram declaration. -- Corresponding_Spec_Of_Stub -- This field is present in subprogram, package, task, and protected body -- stubs where it points to the corresponding spec of the stub. Due to -- clashes in the structure of nodes, we cannot use Corresponding_Spec. -- Corresponding_Stub -- This field is present in an N_Subunit node. It holds the node in -- the parent unit that is the stub declaration for the subunit. It is -- set when analysis of the stub forces loading of the proper body. If -- expansion of the proper body creates new declarative nodes, they are -- inserted at the point of the corresponding_stub. -- Dcheck_Function -- This field is present in an N_Variant node, It references the entity -- for the discriminant checking function for the variant. -- Default_Expression -- This field is Empty if there is no default expression. If there is a -- simple default expression (one with no side effects), then this field -- simply contains a copy of the Expression field (both point to the tree -- for the default expression). Default_Expression is used for -- conformance checking. -- Default_Storage_Pool -- This field is present in N_Compilation_Unit_Aux nodes. It is set to a -- copy of Opt.Default_Pool at the end of the compilation unit. See -- package Opt for details. This is used for inheriting the -- Default_Storage_Pool in child units. -- Discr_Check_Funcs_Built -- This flag is present in N_Full_Type_Declaration nodes. It is set when -- discriminant checking functions are constructed. The purpose is to -- avoid attempting to set these functions more than once. -- Do_Discriminant_Check -- This flag is set on N_Selected_Component nodes to indicate that a -- discriminant check is required using the discriminant check routine -- associated with the selector. The actual check is generated by the -- expander when processing selected components. In the case of -- Unchecked_Union, the flag is also set, but no discriminant check -- routine is associated with the selector, and the expander does not -- generate a check. This flag is also present in assignment statements -- (and set if the assignment requires a discriminant check), and in type -- conversion nodes (and set if the conversion requires a check). -- Do_Division_Check -- This flag is set on a division operator (/ mod rem) to indicate that -- a zero divide check is required. The actual check is either dealt with -- by the back end if Backend_Divide_Checks is set to true, or by the -- front end itself if it is set to false. -- Do_Length_Check -- This flag is set in an N_Assignment_Statement, N_Op_And, N_Op_Or, -- N_Op_Xor, or N_Type_Conversion node to indicate that a length check -- is required. It is not determined who deals with this flag (???). -- Do_Overflow_Check -- This flag is set on an operator where an overflow check is required on -- the operation. The actual check is either dealt with by the back end -- if Backend_Overflow_Checks is set to true, or by the front end itself -- if it is set to false. The other cases where this flag is used is on a -- Type_Conversion node as well on if and case expression nodes. -- For a type conversion, it means that the conversion is from one base -- type to another, and the value may not fit in the target base type. -- See also the description of Do_Range_Check for this case. This flag is -- also set on if and case expression nodes if we are operating in either -- MINIMIZED or ELIMINATED overflow checking mode (to make sure that we -- properly process overflow checking for dependent expressions). -- Do_Range_Check -- This flag is set on an expression which appears in a context where a -- range check is required. The target type is clear from the context. -- The contexts in which this flag can appear are the following: -- Right side of an assignment. In this case the target type is taken -- from the left side of the assignment, which is referenced by the -- Name of the N_Assignment_Statement node. -- Subscript expressions in an indexed component. In this case the -- target type is determined from the type of the array, which is -- referenced by the Prefix of the N_Indexed_Component node. -- Argument expression for a parameter, appearing either directly in -- the Parameter_Associations list of a call or as the Expression of an -- N_Parameter_Association node that appears in this list. In either -- case, the check is against the type of the formal. Note that the -- flag is relevant only in IN and IN OUT parameters, and will be -- ignored for OUT parameters, where no check is required in the call, -- and if a check is required on the return, it is generated explicitly -- with a type conversion. -- Initialization expression for the initial value in an object -- declaration. In this case the Do_Range_Check flag is set on -- the initialization expression, and the check is against the -- range of the type of the object being declared. This includes the -- cases of expressions providing default discriminant values, and -- expressions used to initialize record components. -- The expression of a type conversion. In this case the range check is -- against the target type of the conversion. See also the use of -- Do_Overflow_Check on a type conversion. The distinction is that the -- overflow check protects against a value that is outside the range of -- the target base type, whereas a range check checks that the -- resulting value (which is a value of the base type of the target -- type), satisfies the range constraint of the target type. -- Note: when a range check is required in contexts other than those -- listed above (e.g. in a return statement), an additional type -- conversion node is introduced to represent the required check. -- Do_Storage_Check -- This flag is set in an N_Allocator node to indicate that a storage -- check is required for the allocation, or in an N_Subprogram_Body node -- to indicate that a stack check is required in the subprogram prologue. -- The N_Allocator case is handled by the routine that expands the call -- to the runtime routine. The N_Subprogram_Body case is handled by the -- backend, and all the semantics does is set the flag. -- Elaborate_Present -- This flag is set in the N_With_Clause node to indicate that pragma -- Elaborate pragma appears for the with'ed units. -- Elaborate_All_Desirable -- This flag is set in the N_With_Clause mode to indicate that the static -- elaboration processing has determined that an Elaborate_All pragma is -- desirable for correct elaboration for this unit. -- Elaborate_All_Present -- This flag is set in the N_With_Clause node to indicate that a -- pragma Elaborate_All pragma appears for the with'ed units. -- Elaborate_Desirable -- This flag is set in the N_With_Clause mode to indicate that the static -- elaboration processing has determined that an Elaborate pragma is -- desirable for correct elaboration for this unit. -- Else_Actions -- This field is present in if expression nodes. During code -- expansion we use the Insert_Actions procedure (in Exp_Util) to insert -- actions at an appropriate place in the tree to get elaborated at the -- right time. For if expressions, we have to be sure that the actions -- for the Else branch are only elaborated if the condition is False. -- The Else_Actions field is used as a temporary parking place for -- these actions. The final tree is always rewritten to eliminate the -- need for this field, so in the tree passed to Gigi, this field is -- always set to No_List. -- Enclosing_Variant -- This field is present in the N_Variant node and identifies the Node_Id -- corresponding to the immediately enclosing variant when the variant is -- nested, and N_Empty otherwise. Set during semantic processing of the -- variant part of a record type. -- Entity -- Appears in all direct names (identifiers, character literals, and -- operator symbols), as well as expanded names, and attributes that -- denote entities, such as 'Class. Points to entity for corresponding -- defining occurrence. Set after name resolution. For identifiers in a -- WITH list, the corresponding defining occurrence is in a separately -- compiled file, and Entity must be set by the library Load procedure. -- -- Note: During name resolution, the value in Entity may be temporarily -- incorrect (e.g. during overload resolution, Entity is initially set to -- the first possible correct interpretation, and then later modified if -- necessary to contain the correct value after resolution). -- -- Note: This field overlaps Associated_Node, which is used during -- generic processing (see Sem_Ch12 for details). Note also that in -- generic templates, this means that the Entity field does not always -- point to an Entity. Since the back end is expected to ignore generic -- templates, this is harmless. -- -- Note: This field also appears in N_Attribute_Definition_Clause nodes. -- It is used only for stream attributes definition clauses. In this -- case, it denotes a (possibly dummy) subprogram entity that is declared -- conceptually at the point of the clause. Thus the visibility of the -- attribute definition clause (in the sense of 8.3(23) as amended by -- AI-195) can be checked by testing the visibility of that subprogram. -- -- Note: Normally the Entity field of an identifier points to the entity -- for the corresponding defining identifier, and hence the Chars field -- of an identifier will match the Chars field of the entity. However, -- there is no requirement that these match, and there are obscure cases -- of generated code where they do not match. -- Note: Ada 2012 aspect specifications require additional links between -- identifiers and various attributes. These attributes can be of -- arbitrary types, and the entity field of identifiers that denote -- aspects must be used to store arbitrary expressions for later semantic -- checks. See section on aspect specifications for details. -- Entity_Or_Associated_Node -- A synonym for both Entity and Associated_Node. Used by convention in -- the code when referencing this field in cases where it is not known -- whether the field contains an Entity or an Associated_Node. -- Etype -- Appears in all expression nodes, all direct names, and all entities. -- Points to the entity for the related type. Set after type resolution. -- Normally this is the actual subtype of the expression. However, in -- certain contexts such as the right side of an assignment, subscripts, -- arguments to calls, returned value in a function, initial value etc. -- it is the desired target type. In the event that this is different -- from the actual type, the Do_Range_Check flag will be set if a range -- check is required. Note: if the Is_Overloaded flag is set, then Etype -- points to an essentially arbitrary choice from the possible set of -- types. -- Exception_Junk -- This flag is set in a various nodes appearing in a statement sequence -- to indicate that the corresponding node is an artifact of the -- generated code for exception handling, and should be ignored when -- analyzing the control flow of the relevant sequence of statements -- (e.g. to check that it does not end with a bad return statement). -- Exception_Label -- Appears in N_Push_xxx_Label nodes. Points to the entity of the label -- to be used for transforming the corresponding exception into a goto, -- or contains Empty, if this exception is not to be transformed. Also -- appears in N_Exception_Handler nodes, where, if set, it indicates -- that there may be a local raise for the handler, so that expansion -- to allow a goto is required (and this field contains the label for -- this goto). See Exp_Ch11.Expand_Local_Exception_Handlers for details. -- Expansion_Delayed -- Set on aggregates and extension aggregates that need a top-down rather -- than bottom-up expansion. Typically aggregate expansion happens bottom -- up. For nested aggregates the expansion is delayed until the enclosing -- aggregate itself is expanded, e.g. in the context of a declaration. To -- delay it we set this flag. This is done to avoid creating a temporary -- for each level of a nested aggregate, and also to prevent the -- premature generation of constraint checks. This is also a requirement -- if we want to generate the proper attachment to the internal -- finalization lists (for record with controlled components). Top down -- expansion of aggregates is also used for in-place array aggregate -- assignment or initialization. When the full context is known, the -- target of the assignment or initialization is used to generate the -- left-hand side of individual assignment to each subcomponent. -- Expression_Copy -- Present in N_Pragma_Argument_Association nodes. Contains a copy of the -- original expression. This field is best used to store pragma-dependent -- modifications performed on the original expression such as replacement -- of the current type instance or substitutions of primitives. -- First_Inlined_Subprogram -- Present in the N_Compilation_Unit node for the main program. Points -- to a chain of entities for subprograms that are to be inlined. The -- Next_Inlined_Subprogram field of these entities is used as a link -- pointer with Empty marking the end of the list. This field is Empty -- if there are no inlined subprograms or inlining is not active. -- First_Named_Actual -- Present in procedure call statement and function call nodes, and also -- in Intrinsic nodes. Set during semantic analysis to point to the first -- named parameter where parameters are ordered by declaration order (as -- opposed to the actual order in the call which may be different due to -- named associations). Note: this field points to the explicit actual -- parameter itself, not the N_Parameter_Association node (its parent). -- First_Subtype_Link -- Present in N_Freeze_Entity node for an anonymous base type that is -- implicitly created by the declaration of a first subtype. It points -- to the entity for the first subtype. -- Float_Truncate -- A flag present in type conversion nodes. It is used for floating-point -- to fixed-point or integer conversions, where truncation is required -- rather than rounding. -- Forwards_OK -- A flag present in the N_Assignment_Statement node. It is used only -- if the type being assigned is an array type, and is set if analysis -- determines that it is definitely safe to do the copy forwards, i.e. -- starting at the lowest addressed element. This is the case if either -- the operands do not overlap, or they may overlap, but if they do, -- then the left operand is at a lower address than the right operand. -- -- Note: If neither of the flags Forwards_OK or Backwards_OK is set, it -- means that the front end could not determine that either direction is -- definitely safe, and a runtime check may be required if the backend -- cannot figure it out. If both flags Forwards_OK and Backwards_OK are -- set, it means that the front end can assure no overlap of operands. -- For_Special_Return_Object -- Present in N_Allocator nodes. True if the allocator is generated for -- the initialization of a special return object. -- From_Aspect_Specification -- Processing of aspect specifications typically results in insertion in -- the tree of corresponding pragma or attribute definition clause nodes. -- These generated nodes have the From_Aspect_Specification flag set to -- indicate that they came from aspect specifications originally. -- From_At_Mod -- This flag is set on the attribute definition clause node that is -- generated by a transformation of an at mod phrase in a record -- representation clause. This is used to give slightly different (Ada 83 -- compatible) semantics to such a clause, namely it is used to specify a -- minimum acceptable alignment for the base type and all subtypes. In -- Ada 95 terms, the actual alignment of the base type and all subtypes -- must be a multiple of the given value, and the representation clause -- is considered to be type specific instead of subtype specific. -- From_Conditional_Expression -- This flag is set on if and case statements generated by the expansion -- of if and case expressions respectively. The flag is used to suppress -- any finalization of controlled objects found within these statements. -- From_Default -- This flag is set on the subprogram renaming declaration created in an -- instance for a formal subprogram, when the formal is declared with a -- box, and there is no explicit actual. If the flag is present, the -- declaration is treated as an implicit reference to the formal in the -- ali file. -- Generalized_Indexing -- Present in N_Indexed_Component nodes. Set for Indexed_Component nodes -- that are Ada 2012 container indexing operations. The value of the -- attribute is a function call (possibly dereferenced) that corresponds -- to the proper expansion of the source indexing operation. Before -- expansion, the source node is rewritten as the resolved generalized -- indexing. -- Generic_Parent -- Generic_Parent is defined on declaration nodes that are instances. The -- value of Generic_Parent is the generic entity from which the instance -- is obtained. -- Generic_Parent_Type -- Generic_Parent_Type is defined on Subtype_Declaration nodes for the -- actuals of formal private and derived types. Within the instance, the -- operations on the actual are those inherited from the parent. For a -- formal private type, the parent type is the generic type itself. The -- Generic_Parent_Type is also used in an instance to determine whether a -- private operation overrides an inherited one. -- Handler_List_Entry -- This field is present in N_Object_Declaration nodes. It is set only -- for the Handler_Record entry generated for an exception in zero cost -- exception handling mode. It references the corresponding item in the -- handler list, and is used to delete this entry if the corresponding -- handler is deleted during optimization. For further details on why -- this is required, see Exp_Ch11.Remove_Handler_Entries. -- Has_Dereference_Action -- This flag is present in N_Explicit_Dereference nodes. It is set to -- indicate that the expansion has aready produced a call to primitive -- Dereference of a System.Checked_Pools.Checked_Pool implementation. -- Such dereference actions are produced for debugging purposes. -- Has_Dynamic_Length_Check -- This flag is present in all expression nodes. It is set to indicate -- that one of the routines in unit Checks has generated a length check -- action which has been inserted at the flagged node. This is used to -- avoid the generation of duplicate checks. -- Has_Local_Raise -- Present in exception handler nodes. Set if the handler can be entered -- via a local raise that gets transformed to a goto statement. This will -- always be set if Local_Raise_Statements is non-empty, but can also be -- set as a result of generation of N_Raise_xxx nodes, or flags set in -- nodes requiring generation of back end checks. -- Has_No_Elaboration_Code -- A flag that appears in the N_Compilation_Unit node to indicate whether -- or not elaboration code is present for this unit. It is initially set -- true for subprogram specs and bodies and for all generic units and -- false for non-generic package specs and bodies. Gigi may set the flag -- in the non-generic package case if it determines that no elaboration -- code is generated. Note that this flag is not related to the -- Is_Preelaborated status, there can be preelaborated packages that -- generate elaboration code, and non-preelaborated packages which do -- not generate elaboration code. -- Has_Pragma_Suppress_All -- This flag is set in an N_Compilation_Unit node if the Suppress_All -- pragma appears anywhere in the unit. This accommodates the rather -- strange placement rules of other compilers (DEC permits it at the -- end of a unit, and Rational allows it as a program unit pragma). We -- allow it anywhere at all, and consider it equivalent to a pragma -- Suppress (All_Checks) appearing at the start of the configuration -- pragmas for the unit. -- Has_Private_View -- A flag present in generic nodes that have an entity, to indicate that -- the node has a private type. Used to exchange private and full -- declarations if the visibility at instantiation is different from the -- visibility at generic definition. -- Has_Relative_Deadline_Pragma -- A flag present in N_Subprogram_Body and N_Task_Definition nodes to -- flag the presence of a pragma Relative_Deadline. -- Has_Secondary_Private_View -- A flag present in generic nodes that have an entity, to indicate that -- the node is either of an access type whose Designated_Type is private -- or of an array type whose Component_Type is private. Used to exchange -- private and full declarations if the visibility at instantiation is -- different from the visibility at generic definition. -- Has_Self_Reference -- Present in N_Aggregate and N_Extension_Aggregate. Indicates that one -- of the expressions contains an access attribute reference to the -- enclosing type. Such a self-reference can only appear in default- -- initialized aggregate for a record type. -- Has_SP_Choice -- Present in all nodes containing a Discrete_Choices field (N_Variant, -- N_Case_Expression_Alternative, N_Case_Statement_Alternative). Set to -- True if the Discrete_Choices list has at least one occurrence of a -- statically predicated subtype. -- Has_Storage_Size_Pragma -- A flag present in an N_Task_Definition node to flag the presence of a -- Storage_Size pragma. -- Has_Target_Names -- Present in assignment statements. Indicates that the RHS contains -- target names (see AI12-0125-3) and must be expanded accordingly. -- Has_Wide_Character -- Present in string literals, set if any wide character (i.e. character -- code outside the Character range but within Wide_Character range) -- appears in the string. Used to implement pragma preference rules. -- Has_Wide_Wide_Character -- Present in string literals, set if any wide character (i.e. character -- code outside the Wide_Character range) appears in the string. Used to -- implement pragma preference rules. -- Header_Size_Added -- Present in N_Attribute_Reference nodes, set only for attribute -- Max_Size_In_Storage_Elements. The flag indicates that the size of the -- hidden list header used by the runtime finalization support has been -- added to the size of the prefix. The flag also prevents the infinite -- expansion of the same attribute in the said context. -- Hidden_By_Use_Clause -- An entity list present in use clauses that appear within -- instantiations. For the resolution of local entities, entities -- introduced by these use clauses have priority over global ones, -- and outer entities must be explicitly hidden/restored on exit. -- Implicit_With -- Present in N_With_Clause nodes. The flag indicates that the clause -- does not comes from source and introduces an implicit dependency on -- a particular unit. Such implicit with clauses are generated by: -- -- * ABE mechanism - The static elaboration model of both the default -- and the legacy ABE mechanism use with clauses to encode implicit -- Elaborate[_All] pragmas. -- -- * Analysis - A with clause for child unit A.B.C is equivalent to -- a series of clauses that with A, A.B, and A.B.C. Manipulation of -- contexts utilizes implicit with clauses to emulate the visibility -- of a particular unit. -- -- * RTSfind - The compiler generates code which references entities -- from the runtime. -- Import_Interface_Present -- This flag is set in an Interface or Import pragma if a matching -- pragma of the other kind is also present. This is used to avoid -- generating some unwanted error messages. -- Includes_Infinities -- This flag is present in N_Range nodes. It is set for the range of -- unconstrained float types defined in Standard, which include not only -- the given range of values, but also legitimately can include infinite -- values. This flag is false for any float type for which an explicit -- range is given by the programmer, even if that range is identical to -- the range for Float. -- Incomplete_View -- Present in full type declarations that are completions of incomplete -- type declarations. Denotes the corresponding incomplete view declared -- by the incomplete declaration. -- Inherited_Discriminant -- This flag is present in N_Component_Association nodes. It indicates -- that a given component association in an extension aggregate is the -- value obtained from a constraint on an ancestor. Used to prevent -- double expansion when the aggregate has expansion delayed. -- Instance_Spec -- This field is present in generic instantiation nodes, and also in -- formal package declaration nodes (formal package declarations are -- treated in a manner very similar to package instantiations). It points -- to the node for the spec of the instance, inserted as part of the -- semantic processing for instantiations in Sem_Ch12. -- Is_Abort_Block -- Present in N_Block_Statement nodes. True if the block protects a list -- of statements with an Abort_Defer / Abort_Undefer_Direct pair. -- Is_Accessibility_Actual -- Present in N_Parameter_Association nodes. True if the parameter is -- an extra actual that carries the accessibility level of the actual -- for an access parameter, in a function that dispatches on result and -- is called in a dispatching context. Used to prevent a formal/actual -- mismatch when the call is rewritten as a dispatching call. -- Is_Analyzed_Pragma -- Present in N_Pragma nodes. Set for delayed pragmas that require a two -- step analysis. The initial step is performed by routine Analyze_Pragma -- and verifies the overall legality of the pragma. The second step takes -- place in the various Analyze_xxx_In_Decl_Part routines which perform -- full analysis. The flag prevents the reanalysis of a delayed pragma. -- Is_Asynchronous_Call_Block -- A flag set in a Block_Statement node to indicate that it is the -- expansion of an asynchronous entry call. Such a block needs cleanup -- handler to assure that the call is cancelled. -- Is_Boolean_Aspect -- Present in N_Aspect_Specification node. Set if the aspect is for a -- boolean aspect (i.e. Aspect_Id is in Boolean_Aspect subtype). -- Is_Checked -- Present in N_Aspect_Specification and N_Pragma nodes. Set for an -- assertion aspect or pragma, or check pragma for an assertion, that -- is to be checked at run time. If either Is_Checked or Is_Ignored -- is set (they cannot both be set), then this means that the status of -- the pragma has been checked at the appropriate point and should not -- be further modified (in some cases these flags are copied when a -- pragma is rewritten). -- Is_Checked_Ghost_Pragma -- This flag is present in N_Pragma nodes. It is set when the pragma is -- related to a checked Ghost entity or encloses a checked Ghost entity. -- This flag has no relation to Is_Checked. -- Is_Component_Left_Opnd -- Is_Component_Right_Opnd -- Present in concatenation nodes, to indicate that the corresponding -- operand is of the component type of the result. Used in resolving -- concatenation nodes in instances. -- Is_Controlling_Actual -- This flag is set on an expression that is a controlling argument in -- a dispatching call. It is off in all other cases. See Sem_Disp for -- details of its use. -- Is_Declaration_Level_Node -- Present in call marker and instantiation nodes. Set when the constuct -- appears within the declarations of a block statement, an entry body, -- a subprogram body, or a task body. The flag aids the ABE Processing -- phase to catch certain forms of guaranteed ABEs. -- Is_Delayed_Aspect -- Present in N_Pragma and N_Attribute_Definition_Clause nodes which -- come from aspect specifications, where the evaluation of the aspect -- must be delayed to the freeze point. This flag is also set True in -- the corresponding N_Aspect_Specification node. -- Is_Disabled -- A flag set in an N_Aspect_Specification or N_Pragma node if there was -- a Check_Policy or Assertion_Policy (or in the case of a Debug_Pragma) -- a Debug_Policy pragma that resulted in totally disabling the flagged -- aspect or policy as a result of using the GNAT-defined policy DISABLE. -- If this flag is set, the aspect or policy is not analyzed for semantic -- correctness, so any expressions etc will not be marked as analyzed. -- Is_Dispatching_Call -- Present in call marker nodes. Set when the related call which prompted -- the creation of the marker is dispatching. -- Is_Dynamic_Coextension -- Present in allocator nodes, to indicate that this is an allocator -- for an access discriminant of a dynamically allocated object. The -- coextension must be deallocated and finalized at the same time as -- the enclosing object. The partner flag Is_Static_Coextension must -- be cleared before setting this flag to True. -- Is_Effective_Use_Clause -- Present in both N_Use_Type_Clause and N_Use_Package_Clause to indicate -- a use clause is "used" in the current source. -- Is_Elaboration_Checks_OK_Node -- Present in the following nodes: -- -- assignment statement -- attribute reference -- call marker -- entry call statement -- expanded name -- function call -- function instantiation -- identifier -- package instantiation -- procedure call statement -- procedure instantiation -- requeue statement -- variable reference marker -- -- Set when the node appears within a context which allows the generation -- of run-time ABE checks. This flag determines whether the ABE -- Processing phase generates conditional ABE checks and guaranteed ABE -- failures. -- Is_Elaboration_Code -- Present in assignment statements. Set for an assignment which updates -- the elaboration flag of a package or subprogram when the corresponding -- body is successfully elaborated. -- Is_Elaboration_Warnings_OK_Node -- Present in the following nodes: -- -- attribute reference -- call marker -- entry call statement -- expanded name -- function call -- function instantiation -- identifier -- package instantiation -- procedure call statement -- procedure instantiation -- requeue statement -- variable reference marker -- -- Set when the node appears within a context where elaboration warnings -- are enabled. This flag determines whether the ABE processing phase -- generates diagnostics on various elaboration issues. -- Is_Entry_Barrier_Function -- This flag is set on N_Subprogram_Declaration and N_Subprogram_Body -- nodes which emulate the barrier function of a protected entry body. -- The flag is used when checking for incorrect use of Current_Task. -- Is_Enum_Array_Aggregate -- A flag set on an aggregate created internally while building the -- images tables for enumerations. -- Is_Expanded_Build_In_Place_Call -- This flag is set in an N_Function_Call node to indicate that the extra -- actuals to support a build-in-place style of call have been added to -- the call. -- Is_Expanded_Contract -- Present in N_Contract nodes. Set if the contract has already undergone -- expansion activities. -- Is_Generic_Contract_Pragma -- This flag is present in N_Pragma nodes. It is set when the pragma is -- a source construct, applies to a generic unit or its body, and denotes -- one of the following contract-related annotations: -- Abstract_State -- Always_Terminates -- Contract_Cases -- Depends -- Exceptional_Cases -- Extensions_Visible -- Global -- Initial_Condition -- Initializes -- Post -- Post_Class -- Postcondition -- Pre -- Pre_Class -- Precondition -- Refined_Depends -- Refined_Global -- Refined_Post -- Refined_State -- Subprogram_Variant -- Test_Case -- Is_Homogeneous_Aggregate -- A flag set on an Ada 2022 aggregate that uses square brackets as -- delimiters, and thus denotes an array or container aggregate, or -- the prefix of a reduction attribute. -- Is_Ignored -- A flag set in an N_Aspect_Specification or N_Pragma node if there was -- a Check_Policy or Assertion_Policy (or in the case of a Debug_Pragma) -- a Debug_Policy pragma that specified a policy of IGNORE, DISABLE, or -- OFF, for the pragma/aspect. If there was a Policy pragma specifying -- a Policy of ON or CHECK, then this flag is reset. If no Policy pragma -- gives a policy for the aspect or pragma, then there are two cases. For -- an assertion aspect or pragma (one of the assertion kinds allowed in -- an Assertion_Policy pragma), then Is_Ignored is set if assertions are -- ignored because of the absence of a -gnata switch. For any other -- aspects or pragmas, the flag is off. If this flag is set, the -- aspect/pragma is fully analyzed and checked for other syntactic -- and semantic errors, but it does not have any semantic effect. -- Is_Ignored_Ghost_Pragma -- This flag is present in N_Pragma nodes. It is set when the pragma is -- related to an ignored Ghost entity or encloses ignored Ghost entity. -- This flag has no relation to Is_Ignored. -- Is_In_Discriminant_Check -- This flag is present in a selected component, and is used to indicate -- that the reference occurs within a discriminant check. The -- significance is that optimizations based on assuming that the -- discriminant check has a correct value cannot be performed in this -- case (or the discriminant check may be optimized away). -- Is_Inherited_Pragma -- This flag is set in an N_Pragma node that appears in a N_Contract node -- to indicate that the pragma has been inherited from a parent context. -- Is_Initialization_Block -- Defined in block nodes. Set when the block statement was created by -- the finalization machinery to wrap initialization statements. This -- flag aids the ABE Processing phase to suppress the diagnostics of -- finalization actions in initialization contexts. -- Is_Known_Guaranteed_ABE -- NOTE: this flag is shared between the legacy ABE mechanism and the -- default ABE mechanism. -- -- Present in the following nodes: -- -- call marker -- formal package declaration -- function call -- function instantiation -- package instantiation -- procedure call statement -- procedure instantiation -- -- Set when the elaboration or evaluation of the scenario results in -- a guaranteed ABE. The flag is used to suppress the instantiation of -- generic bodies because gigi cannot handle certain forms of premature -- instantiation, as well as to prevent the reexamination of the node by -- the ABE Processing phase. -- Is_Machine_Number -- This flag is set in an N_Real_Literal node to indicate that the value -- is a machine number. This avoids some unnecessary cases of converting -- real literals to machine numbers. -- Is_Null_Loop -- This flag is set in an N_Loop_Statement node if the corresponding loop -- can be determined to be null at compile time. This is used to remove -- the loop entirely at expansion time. -- Is_Overloaded -- A flag present in all expression nodes. Used temporarily during -- overloading determination. The setting of this flag is not relevant -- once overloading analysis is complete. -- Is_Parenthesis_Aggregate -- A flag set on an aggregate that uses parentheses as delimiters -- Is_Power_Of_2_For_Shift -- A flag present only in N_Op_Expon nodes. It is set when the -- exponentiation is of the form 2 ** N, where the type of N is an -- unsigned integral subtype whose size does not exceed the size of -- Standard_Integer (i.e. a type that can be safely converted to -- Natural), and the exponentiation appears as the right operand of an -- integer multiplication or an integer division where the dividend is -- unsigned. It is also required that overflow checking is off for both -- the exponentiation and the multiply/divide node. If this set of -- conditions holds, and the flag is set, then the division or -- multiplication can be (and is) converted to a shift. -- Is_Preelaborable_Call -- Present in call marker nodes. Set when the related call is non-static -- but preelaborable. -- Is_Prefixed_Call -- This flag is set in a selected component within a generic unit, if -- it resolves to a prefixed call to a primitive operation. The flag -- is used to prevent accidental overloadings in an instance, when a -- primitive operation and a private record component may be homographs. -- Is_Protected_Subprogram_Body -- A flag set in a Subprogram_Body block to indicate that it is the -- implementation of a protected subprogram. Such a body needs cleanup -- handler to make sure that the associated protected object is unlocked -- when the subprogram completes. -- Is_Qualified_Universal_Literal -- Present in N_Qualified_Expression nodes. Set when the qualification is -- converting a universal literal to a specific type. Such qualifiers aid -- the resolution of accidental overloading of binary or unary operators -- which may occur in instances. -- Is_Read -- Present in variable reference markers. Set when the original variable -- reference constitutes a read of the variable. -- Is_Source_Call -- Present in call marker nodes. Set when the related call came from -- source. -- Is_SPARK_Mode_On_Node -- Present in the following nodes: -- -- assignment statement -- attribute reference -- call marker -- entry call statement -- expanded name -- function call -- function instantiation -- identifier -- package instantiation -- procedure call statement -- procedure instantiation -- requeue statement -- variable reference marker -- -- Set when the node appears within a context subject to SPARK_Mode On. -- This flag determines when the SPARK model of elaboration be activated -- by the ABE Processing phase. -- Is_Static_Coextension -- Present in N_Allocator nodes. Set if the allocator is a coextension -- of an object allocated on the stack rather than the heap. The partner -- flag Is_Dynamic_Coextension must be cleared before setting this flag -- to True. -- Is_Static_Expression -- Indicates that an expression is a static expression according to the -- rules in RM-4.9. See Sem_Eval for details. -- Is_Subprogram_Descriptor -- Present in N_Object_Declaration, and set only for the object -- declaration generated for a subprogram descriptor in fast exception -- mode. See Exp_Ch11 for details of use. -- Is_Task_Allocation_Block -- A flag set in a Block_Statement node to indicate that it is the -- expansion of a task allocator, or the allocator of an object -- containing tasks. Such a block requires a cleanup handler to call -- Expunge_Unactivated_Tasks to complete any tasks that have been -- allocated but not activated when the allocator completes abnormally. -- Is_Task_Body_Procedure -- This flag is set on N_Subprogram_Declaration and N_Subprogram_Body -- nodes which emulate the body of a task unit. -- Is_Task_Master -- A flag set in a Subprogram_Body, Block_Statement, or Task_Body node to -- indicate that the construct is a task master (i.e. has declared tasks -- or declares an access to a task type). -- Is_Write -- Present in variable reference markers. Set when the original variable -- reference constitutes a write of the variable. -- Iterator_Filter -- Present in N_Loop_Parameter_Specification and N_Iterator_Specification -- nodes for Ada 2022. It is used to store the condition present in the -- eponymous Ada 2022 construct. -- Itype -- Used in N_Itype_Reference node to reference an itype for which it is -- important to ensure that it is defined. See description of this node -- for further details. -- Kill_Range_Check -- Used in an N_Unchecked_Type_Conversion node to indicate that the -- result should not be subjected to range checks. This is used for the -- implementation of Normalize_Scalars. -- Label_Construct -- Used in an N_Implicit_Label_Declaration node. Refers to an N_Label, -- N_Block_Statement or N_Loop_Statement node to which the label -- declaration applies. The field is left empty for the special labels -- generated as part of expanding raise statements with a local exception -- handler. -- Library_Unit -- In a stub node, Library_Unit points to the compilation unit node of -- the corresponding subunit. -- -- In a with clause node, Library_Unit points to the spec of the with'ed -- unit. -- -- In a compilation unit node, the usage depends on the unit type: -- -- For a library unit body, Library_Unit points to the compilation unit -- node of the corresponding spec, unless it's a subprogram body with -- Acts_As_Spec set, in which case it points to itself. -- -- For a spec, Library_Unit points to the compilation unit node of the -- corresponding body, if present. The body will be present if the spec -- is or contains generics that we needed to instantiate. Similarly, the -- body will be present if we needed it for inlining purposes. Thus, if -- we have a spec/body pair, both of which are present, they point to -- each other via Library_Unit. -- -- For a subunit, Library_Unit points to the compilation unit node of -- the parent body. -- ??? not (always) true, in (at least some, maybe all?) cases it points -- to the corresponding spec for the parent body. -- -- Note that this field is not used to hold the parent pointer for child -- unit (which might in any case need to use it for some other purpose as -- described above). Instead for a child unit, implicit with's are -- generated for all parents. -- Local_Raise_Statements -- This field is present in exception handler nodes. It is set to -- No_Elist in the normal case. If there is at least one raise statement -- which can potentially be handled as a local raise, then this field -- points to a list of raise nodes, which are calls to a routine to raise -- an exception. These are raise nodes which can be optimized into gotos -- if the handler turns out to meet the conditions which permit this -- transformation. Note that this does NOT include instances of the -- N_Raise_xxx_Error nodes since the transformation of these nodes is -- handled by the back end (using the N_Push/N_Pop mechanism). -- Loop_Actions -- A list present in Component_Association nodes in array aggregates. -- Used to collect actions that must be executed within the loop because -- they may need to be evaluated anew each time through. -- Limited_View_Installed -- Present in With_Clauses and in package specifications. If set on -- with_clause, it indicates that this clause has created the current -- limited view of the designated package. On a package specification, it -- indicates that the limited view has already been created because the -- package is mentioned in a limited_with_clause in the closure of the -- unit being compiled. -- Local_Raise_Not_OK -- Present in N_Exception_Handler nodes. Set if the handler contains -- a construct (reraise statement, or call to subprogram in package -- GNAT.Current_Exception) that makes the handler unsuitable as a target -- for a local raise (one that could otherwise be converted to a goto). -- Must_Be_Byte_Aligned -- This flag is present in N_Attribute_Reference nodes. It can be set -- only for the Address and Unrestricted_Access attributes. If set it -- means that the object for which the address/access is given must be on -- a byte (more accurately a storage unit) boundary. If necessary, a copy -- of the object is to be made before taking the address (this copy is in -- the current scope on the stack frame). This is used for certain cases -- of code generated by the expander that passes parameters by address. -- -- The reason the copy is not made by the front end is that the back end -- has more information about type layout and may be able to (but is not -- guaranteed to) prevent making unnecessary copies. -- Must_Not_Freeze -- A flag present in all expression nodes. Normally expressions cause -- freezing as described in the RM. If this flag is set, then this is -- inhibited. This is used by the analyzer and expander to label nodes -- that are created by semantic analysis or expansion and which must not -- cause freezing even though they normally would. This flag is also -- present in an N_Subtype_Indication node, since we also use these in -- calls to Freeze_Expression. -- Next_Entity -- Present in defining identifiers, defining character literals, and -- defining operator symbols (i.e. in all entities). The entities of a -- scope are chained, and this field is used as the forward pointer for -- this list. See Einfo for further details. -- Next_Exit_Statement -- Present in N_Exit_Statement nodes. The exit statements for a loop are -- chained (in reverse order of appearance) from the First_Exit_Statement -- field of the E_Loop entity for the loop. Next_Exit_Statement points to -- the next entry on this chain (Empty = end of list). -- Next_Implicit_With -- Present in N_With_Clause. Part of a chain of with_clauses generated -- in rtsfind to indicate implicit dependencies on predefined units. Used -- to prevent multiple with_clauses for the same unit in a given context. -- A postorder traversal of the tree whose nodes are units and whose -- links are with_clauses defines the order in which CodePeer must -- examine a compiled unit and its full context. This ordering ensures -- that any subprogram call is examined after the subprogram declaration -- has been seen. -- Next_Named_Actual -- Present in parameter association nodes. Set during semantic analysis -- to point to the next named parameter, where parameters are ordered by -- declaration order (as opposed to the actual order in the call, which -- may be different due to named associations). Not that this field -- points to the explicit actual parameter itself, not to the -- N_Parameter_Association node (its parent). -- Next_Pragma -- Present in N_Pragma nodes. Used to create a linked list of pragma -- nodes. Currently used for two purposes: -- -- Create a list of linked Check_Policy pragmas. The head of this list -- is stored in Opt.Check_Policy_List (which has further details). -- -- Used by processing for Pre/Postcondition pragmas to store a list of -- pragmas associated with the spec of a subprogram (see Sem_Prag for -- details). -- -- Used by processing for pragma SPARK_Mode to store multiple pragmas -- the apply to the same construct. These are visible/private mode for -- a package spec and declarative/statement mode for package body. -- Next_Rep_Item -- Present in pragma nodes, attribute definition nodes, enumeration rep -- clauses, record rep clauses, aspect specification and null statement -- nodes. Used to link representation items that apply to an entity. See -- full description of First_Rep_Item field in Einfo for further details. -- Next_Use_Clause -- While use clauses are active during semantic processing, they are -- chained from the scope stack entry, using Next_Use_Clause as a link -- pointer, with Empty marking the end of the list. The head pointer is -- in the scope stack entry (First_Use_Clause). At the end of semantic -- processing (i.e. when Gigi sees the tree, the contents of this field -- is undefined and should not be read). -- No_Ctrl_Actions -- Present in N_Assignment_Statement to indicate that neither Finalize -- nor Adjust should take place on this assignment even though the LHS -- and RHS are controlled. Also to indicate that the primitive _assign -- should not be used for a tagged assignment. This flag is used in init -- proc and aggregate expansion where the generated assignments are -- initializations, not real assignments. Note that it also suppresses -- the creation of transient scopes around the N_Assignment_Statement, -- in other words it disables all controlled actions for the assignment. -- No_Elaboration_Check -- NOTE: this flag is relevant only for the legacy ABE mechanism and -- should not be used outside of that context. -- -- Present in N_Function_Call and N_Procedure_Call_Statement. Indicates -- that no elaboration check is needed on the call, because it appears in -- the context of a local Suppress pragma. This is used on calls within -- task bodies, where the actual elaboration checks are applied after -- analysis, when the local scope stack is not present. -- No_Entities_Ref_In_Spec -- Present in N_With_Clause nodes. Set if the with clause is on the -- package or subprogram spec where the main unit is the corresponding -- body, and no entities of the with'ed unit are referenced by the spec -- (an entity may still be referenced in the body, so this flag is used -- to generate the proper message (see Sem_Util.Check_Unused_Withs for -- full details). -- No_Finalize_Actions -- Present in N_Assignment_Statement to indicate that no Finalize should -- take place on this assignment even though the LHS is controlled. Also -- to indicate that the primitive _assign should not be used for a tagged -- assignment. This flag is only used in aggregates expansion where the -- generated assignments are initializations, not real assignments. Note -- that, unlike the No_Ctrl_Actions flag, it does *not* suppress the -- creation of transient scopes around the N_Assignment_Statement. -- No_Initialization -- Present in N_Object_Declaration and N_Allocator to indicate that the -- object must not be initialized (by Initialize or call to an init -- proc). This is needed for controlled aggregates. When the Object -- declaration has an expression, this flag means that this expression -- should not be taken into account (needed for in place initialization -- with aggregates, and for object with an address clause, which are -- initialized with an assignment at freeze time). -- No_Minimize_Eliminate -- This flag is present in membership operator nodes (N_In/N_Not_In). -- It is used to indicate that processing for extended overflow checking -- modes is not required (this is used to prevent infinite recursion). -- No_Truncation -- Present in N_Unchecked_Type_Conversion node. This flag has an effect -- only if the RM_Size of the source is greater than the RM_Size of the -- target for scalar operands. Normally in such a case we truncate some -- higher order bits of the source, and then sign/zero extend the result -- to form the output value. But if this flag is set, then we do not do -- any truncation, so for example, if an 8 bit input is converted to 5 -- bit result which is in fact stored in 8 bits, then the high order -- three bits of the target result will be copied from the source. This -- is used for properly setting out of range values for use by pragmas -- Initialize_Scalars and Normalize_Scalars. -- Null_Excluding_Subtype -- Present in N_Access_To_Object_Definition. Indicates that the subtype -- indication carries a null-exclusion indicator, which is distinct from -- the null-exclusion indicator that may precede the access keyword. -- Original_Discriminant -- Present in identifiers. Used in references to discriminants that -- appear in generic units. Because the names of the discriminants may be -- different in an instance, we use this field to recover the position of -- the discriminant in the original type, and replace it with the -- discriminant at the same position in the instantiated type. -- Original_Entity -- Present in numeric literals. Used to denote the named number that has -- been constant-folded into the given literal. If literal is from -- source, or the result of some other constant-folding operation, then -- Original_Entity is empty. This field is needed to handle properly -- named numbers in generic units, where the Associated_Node field -- interferes with the Entity field, making it impossible to preserve the -- original entity at the point of instantiation. -- Others_Discrete_Choices -- When a case statement or variant is analyzed, the semantic checks -- determine the actual list of choices that correspond to an others -- choice. This list is materialized for later use by the expander and -- the Others_Discrete_Choices field of an N_Others_Choice node points to -- this materialized list of choices, which is in standard format for a -- list of discrete choices, except that of course it cannot contain an -- N_Others_Choice entry. -- Parent_Spec -- For a library unit that is a child unit spec (package or subprogram -- declaration, generic declaration or instantiation, or library level -- rename) this field points to the compilation unit node for the parent -- package specification. This field is Empty for library bodies (the -- parent spec in this case can be found from the corresponding spec). -- Parent_With -- Present in N_With_Clause nodes. The flag indicates that the clause -- was generated for an ancestor unit to provide proper visibility. A -- with clause for child unit A.B.C produces two implicit parent with -- clauses for A and A.B. -- Premature_Use -- Present in N_Incomplete_Type_Declaration node. Used for improved -- error diagnostics: if there is a premature usage of an incomplete -- type, a subsequently generated error message indicates the position -- of its full declaration. -- Present_Expr -- Present in an N_Variant node. This has a meaningful value only after -- Gigi has back annotated the tree with representation information. At -- this point, it contains a reference to a gcc expression that depends -- on the values of one or more discriminants. Given a set of -- discriminant values, this expression evaluates to False (zero) if -- variant is not present, and True (non-zero) if it is present. See -- unit Repinfo for further details on gigi back annotation. This field -- is used during back-annotation processing (for -gnatR -gnatc) to -- determine if a field is present or not. -- Prev_Use_Clause -- Present in both N_Use_Package_Clause and N_Use_Type_Clause. Used in -- detection of ineffective use clauses by allowing a chain of related -- clauses together to avoid traversing the current scope stack. -- Print_In_Hex -- Set on an N_Integer_Literal node to indicate that the value should be -- printed in hexadecimal in the sprint listing. Has no effect on -- legality or semantics of program, only on the displayed output. This -- is used to clarify output from the packed array cases. -- Procedure_To_Call -- Present in N_Allocator, N_Free_Statement, N_Simple_Return_Statement, -- and N_Extended_Return_Statement nodes. References the entity for the -- declaration of the procedure to be called to accomplish the required -- operation (i.e. for the Allocate procedure in the case of N_Allocator -- and N_Simple_Return_Statement and N_Extended_Return_Statement (for -- allocating the return value), and for the Deallocate procedure in the -- case of N_Free_Statement. -- Raises_Constraint_Error -- Set on an expression whose evaluation will definitely fail constraint -- error check. See Sem_Eval for details. -- Redundant_Use -- Present in nodes that can appear as an operand in a use clause or use -- type clause (identifiers, expanded names, attribute references). Set -- to indicate that a use is redundant (and therefore need not be undone -- on scope exit). -- Renaming_Exception -- Present in N_Exception_Declaration node. Used to point back to the -- exception renaming for an exception declared within a subprogram. -- What happens is that an exception declared in a subprogram is moved -- to the library level with a unique name, and the original exception -- becomes a renaming. This link from the library level exception to the -- renaming declaration allows registering of the proper exception name. -- Return_Statement_Entity -- Present in N_Simple_Return_Statement and N_Extended_Return_Statement. -- Points to an E_Return_Statement representing the return statement. -- Return_Object_Declarations -- Present in N_Extended_Return_Statement. Points to a list initially -- containing a single N_Object_Declaration representing the return -- object. We use a list (instead of just a pointer to the object decl) -- because Analyze wants to insert extra actions on this list, before the -- N_Object_Declaration, which always remains last on the list. -- Rounded_Result -- Present in N_Type_Conversion, N_Op_Divide, and N_Op_Multiply nodes. -- Used in the fixed-point cases to indicate that the result must be -- rounded as a result of the use of the 'Round attribute. Also used for -- integer N_Op_Divide nodes to indicate that the result should be -- rounded to the nearest integer (breaking ties away from zero), rather -- than truncated towards zero as usual. These rounded integer operations -- are the result of expansion of rounded fixed-point divide, conversion -- and multiplication operations. -- Save_Invocation_Graph_Of_Body -- Present in compilation unit nodes. Set when the elaboration mechanism -- must record all invocation constructs and invocation relations within -- the body of the compilation unit. -- -- SCIL_Entity -- Present in SCIL nodes. References the specific tagged type associated -- with the SCIL node (for an N_SCIL_Dispatching_Call node, this is -- the controlling type of the call; for an N_SCIL_Membership_Test node -- generated as part of testing membership in T'Class, this is T; for an -- N_SCIL_Dispatch_Table_Tag_Init node, this is the type being declared). -- SCIL_Controlling_Tag -- Present in N_SCIL_Dispatching_Call nodes. References the controlling -- tag of a dispatching call. This is usually an N_Selected_Component -- node (for a _tag component), but may be an N_Object_Declaration or -- N_Parameter_Specification node in some cases (e.g., for a call to -- a classwide streaming operation or a call to an instance of -- Ada.Tags.Generic_Dispatching_Constructor). -- SCIL_Tag_Value -- Present in N_SCIL_Membership_Test nodes. Used to reference the tag -- of the value that is being tested. -- SCIL_Target_Prim -- Present in N_SCIL_Dispatching_Call nodes. References the primitive -- operation named (statically) in a dispatching call. -- Scope -- Present in defining identifiers, defining character literals, and -- defining operator symbols (i.e. in all entities). The entities of a -- scope all use this field to reference the corresponding scope entity. -- See Einfo for further details. -- Shift_Count_OK -- A flag present in shift nodes to indicate that the shift count is -- known to be in range, i.e. is in the range from zero to word length -- minus one. If this flag is not set, then the shift count may be -- outside this range, i.e. larger than the word length, and the code -- must ensure that such shift counts give the appropriate result. -- Source_Type -- Used in an N_Validate_Unchecked_Conversion node to point to the -- source type entity for the unchecked conversion instantiation -- which gigi must do size validation for. -- Split_PPC -- When a Pre or Post aspect specification is processed, it is broken -- into AND THEN sections. The leftmost section has Split_PPC set to -- False, indicating that it is the original specification (e.g. for -- posting errors). For other sections, Split_PPC is set to True. -- This flag is set in both the N_Aspect_Specification node itself, -- and in the pragma which is generated from this node. -- Storage_Pool -- Present in N_Allocator, N_Free_Statement, N_Simple_Return_Statement, -- and N_Extended_Return_Statement nodes. References the entity for the -- storage pool to be used for the allocate or free call or for the -- allocation of the returned value from function. Empty indicates that -- the global default pool is to be used. Note that in the case -- of a return statement, this field is set only if the function returns -- value of a type whose size is not known at compile time on the -- secondary stack. -- Suppress_Assignment_Checks -- Used in generated N_Assignment_Statement nodes to suppress predicate -- and range checks in cases where the generated code knows that the -- value being assigned is in range and satisfies any predicate. Also -- can be set in N_Object_Declaration nodes, to similarly suppress any -- checks on the initializing value. In assignment statements it also -- suppresses access checks in the generated code for out- and in-out -- parameters in entry calls, as well as discriminant and length checks. -- Suppress_Loop_Warnings -- Used in N_Loop_Statement node to indicate that warnings within the -- body of the loop should be suppressed. This is set when the range -- of a FOR loop is known to be null, or is probably null (loop would -- only execute if invalid values are present). -- Target -- Present in call and variable reference marker nodes. References the -- entity of the original entity, operator, or subprogram being invoked, -- or the original variable being read or written. -- Target_Type -- Used in an N_Validate_Unchecked_Conversion node to point to the target -- type entity for the unchecked conversion instantiation which gigi must -- do size validation for. -- Then_Actions -- This field is present in if expression nodes. During code expansion -- we use the Insert_Actions procedure (in Exp_Util) to insert actions -- at an appropriate place in the tree to get elaborated at the right -- time. For if expressions, we have to be sure that the actions for -- for the Then branch are only elaborated if the condition is True. -- The Then_Actions field is used as a temporary parking place for -- these actions. The final tree is always rewritten to eliminate the -- need for this field, so in the tree passed to Gigi, this field is -- always set to No_List. -- TSS_Elist -- Present in N_Freeze_Entity nodes. Holds an element list containing -- entries for each TSS (type support subprogram) associated with the -- frozen type. The elements of the list are the entities for the -- subprograms (see package Exp_TSS for further details). Set to No_Elist -- if there are no type support subprograms for the type or if the freeze -- node is not for a type. -- Uneval_Old_Accept -- Present in N_Pragma nodes. Set True if Opt.Uneval_Old is set to 'A' -- (accept) at the point where the pragma is encountered (including the -- case of a pragma generated from an aspect specification). It is this -- setting that is relevant, rather than the setting at the point where -- a contract is finally analyzed after the delay till the freeze point. -- Uneval_Old_Warn -- Present in N_Pragma nodes. Set True if Opt.Uneval_Old is set to 'W' -- (warn) at the point where the pragma is encountered (including the -- case of a pragma generated from an aspect specification). It is this -- setting that is relevant, rather than the setting at the point where -- a contract is finally analyzed after the delay till the freeze point. -- Unreferenced_In_Spec -- Present in N_With_Clause nodes. Set if the with clause is on the -- package or subprogram spec where the main unit is the corresponding -- body, and is not referenced by the spec (it may still be referenced by -- the body, so this flag is used to generate the proper message (see -- Sem_Util.Check_Unused_Withs for details) -- Uninitialized_Variable -- Present in N_Formal_Private_Type_Definition and in N_Private_ -- Extension_Declarations. Indicates that a variable in a generic unit -- whose type is a formal private or derived type is read without being -- initialized. Used to warn if the corresponding actual type is not -- a fully initialized type. -- Used_Operations -- Present in N_Use_Type_Clause nodes. Holds the list of operations that -- are made potentially use-visible by the clause. Simplifies processing -- on exit from the scope of the use_type_clause, in particular in the -- case of Use_All_Type, when those operations several scopes. -- Was_Attribute_Reference -- Present in N_Subprogram_Body. Set to True if the original source is an -- attribute reference which is an actual in a generic instantiation. The -- instantiation prologue renames these attributes, and expansion later -- converts them into subprogram bodies. -- Was_Expression_Function -- Present in N_Subprogram_Body. True if the original source had an -- N_Expression_Function, which was converted to the N_Subprogram_Body -- by Analyze_Expression_Function. -- Was_Originally_Stub -- This flag is set in the node for a proper body that replaces stub. -- During the analysis procedure, stubs in some situations get rewritten -- by the corresponding bodies, and we set this flag to remember that -- this happened. Note that it is not good enough to rely on the use of -- Original_Node here because of the case of nested instantiations where -- the substituted node can be copied. -------------------------------------------------- -- Note on Use of End_Label and End_Span Fields -- -------------------------------------------------- -- Several constructs have end lines: -- Loop Statement end loop [loop_IDENTIFIER]; -- Package Specification end [[PARENT_UNIT_NAME .] IDENTIFIER] -- Task Definition end [task_IDENTIFIER] -- Protected Definition end [protected_IDENTIFIER] -- Protected Body end [protected_IDENTIFIER] -- Block Statement end [block_IDENTIFIER]; -- Subprogram Body end [DESIGNATOR]; -- Package Body end [[PARENT_UNIT_NAME .] IDENTIFIER]; -- Task Body end [task_IDENTIFIER]; -- Accept Statement end [entry_IDENTIFIER]]; -- Entry Body end [entry_IDENTIFIER]; -- If Statement end if; -- Case Statement end case; -- Record Definition end record; -- Enumeration Definition ); -- The End_Label and End_Span fields are used to mark the locations of -- these lines, and also keep track of the label in the case where a label -- is present. -- For the first group above, the End_Label field of the corresponding node -- is used to point to the label identifier. In the case where there is no -- label in the source, the parser supplies a dummy identifier (with -- Comes_From_Source set to False), and the Sloc of this dummy identifier -- marks the location of the token following the END token. -- For the second group, the use of End_Label is similar, but the End_Label -- is found in the N_Handled_Sequence_Of_Statements node. This is done -- simply because in some cases there is no room in the parent node. -- For the third group, there is never any label, and instead of using -- End_Label, we use the End_Span field which gives the location of the -- token following END, relative to the starting Sloc of the construct, -- i.e. add Sloc (Node) + End_Span (Node) to get the Sloc of the IF or CASE -- following the End_Label. -- The record definition case is handled specially, we treat it as though -- it required an optional label which is never present, and so the parser -- always builds a dummy identifier with Comes From Source set False. The -- reason we do this, rather than using End_Span in this case, is that we -- want to generate a cross-ref entry for the end of a record, since it -- represents a scope for name declaration purposes. -- The enumeration definition case is handled in an exactly similar manner, -- building a dummy identifier to get a cross-reference. -- Note: the reason we store the difference as a Uint, instead of storing -- the Source_Ptr value directly, is that Source_Ptr values cannot be -- distinguished from other types of values, and we count on all general -- use fields being self describing. To make things easier for clients, -- note that we provide function End_Location, and procedure -- Set_End_Location to allow access to the logical value (which is the -- Source_Ptr value for the end token). --------------------- -- Syntactic Nodes -- --------------------- --------------------- -- 2.3 Identifier -- --------------------- -- IDENTIFIER ::= IDENTIFIER_LETTER {[UNDERLINE] LETTER_OR_DIGIT} -- LETTER_OR_DIGIT ::= IDENTIFIER_LETTER | DIGIT -- An IDENTIFIER shall not be a reserved word -- In the Ada grammar identifiers are the bottom level tokens which have -- very few semantics. Actual program identifiers are direct names. If -- we were being 100% honest with the grammar, then we would have a node -- called N_Direct_Name which would point to an identifier. However, -- that's too many extra nodes, so we just use the N_Identifier node -- directly as a direct name, and it contains the expression fields and -- Entity field that correspond to its use as a direct name. In those -- few cases where identifiers appear in contexts where they are not -- direct names (pragmas, pragma argument associations, attribute -- references and attribute definition clauses), the Chars field of the -- node contains the Name_Id for the identifier name. -- Note: in GNAT, a reserved word can be treated as an identifier in two -- cases. First, an incorrect use of a reserved word as an identifier is -- diagnosed and then treated as a normal identifier. Second, an -- attribute designator of the form of a reserved word (access, delta, -- digits, range) is treated as an identifier. -- Note: The set of letters that is permitted in an identifier depends -- on the character set in use. See package Csets for full details. -- N_Identifier -- Sloc points to identifier -- Chars contains the Name_Id for the identifier -- Entity -- Associated_Node -- Original_Discriminant -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Has_Private_View (set in generic units) -- Has_Secondary_Private_View (set in generic units) -- Redundant_Use -- Atomic_Sync_Required -- plus fields for expression -------------------------- -- 2.4 Numeric Literal -- -------------------------- -- NUMERIC_LITERAL ::= DECIMAL_LITERAL | BASED_LITERAL ---------------------------- -- 2.4.1 Decimal Literal -- ---------------------------- -- DECIMAL_LITERAL ::= NUMERAL [.NUMERAL] [EXPONENT] -- NUMERAL ::= DIGIT {[UNDERLINE] DIGIT} -- EXPONENT ::= E [+] NUMERAL | E - NUMERAL -- Decimal literals appear in the tree as either integer literal nodes -- or real literal nodes, depending on whether a period is present. -- Note: literal nodes appear as a result of direct use of literals -- in the source program, and also as the result of evaluating -- expressions at compile time. In the latter case, it is possible -- to construct real literals that have no syntactic representation -- using the standard literal format. Such literals are listed by -- Sprint using the notation [numerator / denominator]. -- Note: the value of an integer literal node created by the front end -- is never outside the range of values of the base type. However, it -- can be the case that the created value is outside the range of the -- particular subtype. This happens in the case of integer overflows -- with checks suppressed. -- N_Integer_Literal -- Sloc points to literal -- Original_Entity If not Empty, holds Named_Number that -- has been constant-folded into its literal value. -- Intval contains integer value of literal -- Print_In_Hex -- plus fields for expression -- N_Real_Literal -- Sloc points to literal -- Original_Entity If not Empty, holds Named_Number that -- has been constant-folded into its literal value. -- Realval contains real value of literal -- Corresponding_Integer_Value -- Is_Machine_Number -- plus fields for expression -------------------------- -- 2.4.2 Based Literal -- -------------------------- -- BASED_LITERAL ::= -- BASE # BASED_NUMERAL [.BASED_NUMERAL] # [EXPONENT] -- BASE ::= NUMERAL -- BASED_NUMERAL ::= -- EXTENDED_DIGIT {[UNDERLINE] EXTENDED_DIGIT} -- EXTENDED_DIGIT ::= DIGIT | A | B | C | D | E | F -- Based literals appear in the tree as either integer literal nodes -- or real literal nodes, depending on whether a period is present. ---------------------------- -- 2.5 Character Literal -- ---------------------------- -- CHARACTER_LITERAL ::= ' GRAPHIC_CHARACTER ' -- N_Character_Literal -- Sloc points to literal -- Chars contains the Name_Id for the identifier -- Char_Literal_Value contains the literal value -- Entity -- Associated_Node -- Has_Private_View (set in generic units) -- Has_Secondary_Private_View (set in generic units) -- plus fields for expression -- Note: the Entity field will be missing (set to Empty) for character -- literals whose type is Standard.Wide_Character or Standard.Character -- or a type derived from one of these two. In this case the character -- literal stands for its own coding. The reason we take this irregular -- short cut is to avoid the need to build lots of junk defining -- character literal nodes. ------------------------- -- 2.6 String Literal -- ------------------------- -- STRING LITERAL ::= "{STRING_ELEMENT}" -- A STRING_ELEMENT is either a pair of quotation marks ("), or a -- single GRAPHIC_CHARACTER other than a quotation mark. -- -- Is_Folded_In_Parser is True if the parser created this literal by -- folding a sequence of "&" operators. For example, if the source code -- says "aaa" & "bbb" & "ccc", and this produces "aaabbbccc", the flag -- is set. This flag is needed because the parser doesn't know about -- visibility, so the folded result might be wrong, and semantic -- analysis needs to check for that. -- N_String_Literal -- Sloc points to literal -- Strval contains Id of string value -- Has_Wide_Character -- Has_Wide_Wide_Character -- Is_Folded_In_Parser -- plus fields for expression --------------------------------------- -- 2.6 Interpolated String Literal -- --------------------------------------- -- INTERPOLATED_STRING_LITERAL ::= -- '{' "{INTERPOLATED_STRING_ELEMENT}" { -- "{INTERPOLATED_STRING_ELEMENT}" } '}' -- INTERPOLATED_STRING_ELEMENT ::= -- ESCAPED_CHARACTER | INTERPOLATED_EXPRESSION -- | non_quotation_mark_non_left_brace_GRAPHIC_CHARACTER -- ESCAPED_CHARACTER ::= '\GRAPHIC_CHARACTER' -- INTERPOLATED_EXPRESSION ::= '{' EXPRESSION '}' -- Most of these syntax rules are omitted as tree nodes to simplify -- semantic processing. The scanner handles escaped characters as part -- of processing an interpolated string literal, and the parser stores -- in the Expressions field of this node a list containing the sequence -- of string literals and the roots of the interpolated expressions. -- N_Interpolated_String_Literal -- Sloc points to literal -- Expressions -- plus fields for expression ------------------ -- 2.7 Comment -- ------------------ -- A COMMENT starts with two adjacent hyphens and extends up to the -- end of the line. A COMMENT may appear on any line of a program. -- Comments are skipped by the scanner and do not appear in the tree. -- It is possible to reconstruct the position of comments with respect -- to the elements of the tree by using the source position (Sloc) -- pointers that appear in every tree node. ----------------- -- 2.8 Pragma -- ----------------- -- PRAGMA ::= pragma IDENTIFIER -- [(PRAGMA_ARGUMENT_ASSOCIATION {, PRAGMA_ARGUMENT_ASSOCIATION})]; -- Note that a pragma may appear in the tree anywhere a declaration -- or a statement may appear, as well as in some other situations -- which are explicitly documented. -- N_Pragma -- Sloc points to PRAGMA -- Next_Pragma -- Pragma_Argument_Associations (set to No_List if none) -- Corresponding_Aspect (set to Empty if not present) -- Pragma_Identifier -- Next_Rep_Item -- Is_Generic_Contract_Pragma -- Is_Checked_Ghost_Pragma -- Is_Inherited_Pragma -- Is_Analyzed_Pragma -- Class_Present set if from Aspect with 'Class -- Uneval_Old_Accept -- Is_Ignored_Ghost_Pragma -- Is_Ignored -- Is_Checked -- From_Aspect_Specification -- Is_Delayed_Aspect -- Is_Disabled -- Import_Interface_Present -- Split_PPC set if corresponding aspect had Split_PPC set -- Uneval_Old_Warn -- Note: we should have a section on what pragmas are passed on to -- the back end to be processed. This section should note that pragma -- Psect_Object is always converted to Common_Object, but there are -- undoubtedly many other similar notes required ??? -- Note: utility functions Pragma_Name_Unmapped and Pragma_Name may be -- applied to pragma nodes to obtain the Chars or its mapped version. -- Note: if From_Aspect_Specification is set, then Sloc points to the -- aspect name, as does the Pragma_Identifier. In this case if the -- pragma has a local name argument (such as pragma Inline), it is -- resolved to point to the specific entity affected by the pragma. -------------------------------------- -- 2.8 Pragma Argument Association -- -------------------------------------- -- PRAGMA_ARGUMENT_ASSOCIATION ::= -- [pragma_argument_IDENTIFIER =>] NAME -- | [pragma_argument_IDENTIFIER =>] EXPRESSION -- In Ada 2012, there are two more possibilities: -- PRAGMA_ARGUMENT_ASSOCIATION ::= -- [pragma_argument_ASPECT_MARK =>] NAME -- | [pragma_argument_ASPECT_MARK =>] EXPRESSION -- where the interesting allowed cases (which do not fit the syntax of -- the first alternative above) are -- ASPECT_MARK => Pre'Class | -- Post'Class | -- Type_Invariant'Class | -- Invariant'Class -- We allow this special usage in all Ada modes, but it would be a -- pain to allow these aspects to pervade the pragma syntax, and the -- representation of pragma nodes internally. So what we do is to -- replace these ASPECT_MARK forms with identifiers whose name is one -- of the special internal names _Pre, _Post, or _Type_Invariant. -- We do a similar replacement of these Aspect_Mark forms in the -- Expression of a pragma argument association for the cases of -- the first arguments of any Check pragmas and Check_Policy pragmas -- N_Pragma_Argument_Association -- Sloc points to first token in association -- Chars (set to No_Name if no pragma argument identifier) -- Expression_Copy -- Expression ------------------------ -- 2.9 Reserved Word -- ------------------------ -- Reserved words are parsed by the scanner, and returned as the -- corresponding token types (e.g. PACKAGE is returned as Tok_Package) ---------------------------- -- 3.1 Basic Declaration -- ---------------------------- -- BASIC_DECLARATION ::= -- TYPE_DECLARATION | SUBTYPE_DECLARATION -- | OBJECT_DECLARATION | NUMBER_DECLARATION -- | SUBPROGRAM_DECLARATION | ABSTRACT_SUBPROGRAM_DECLARATION -- | PACKAGE_DECLARATION | RENAMING_DECLARATION -- | EXCEPTION_DECLARATION | GENERIC_DECLARATION -- | GENERIC_INSTANTIATION -- Basic declaration also includes IMPLICIT_LABEL_DECLARATION -- see further description in section on semantic nodes. -- Also, in the tree that is constructed, a pragma may appear -- anywhere that a declaration may appear. ------------------------------ -- 3.1 Defining Identifier -- ------------------------------ -- DEFINING_IDENTIFIER ::= IDENTIFIER -- A defining identifier is an entity, which has additional fields -- depending on the setting of the Ekind field. These additional -- fields are defined (and access subprograms declared) in package -- Einfo. -- N_Defining_Identifier -- Sloc points to identifier -- Chars contains the Name_Id for the identifier -- Next_Entity -- Scope -- Etype ----------------------------- -- 3.2.1 Type Declaration -- ----------------------------- -- TYPE_DECLARATION ::= -- FULL_TYPE_DECLARATION -- | INCOMPLETE_TYPE_DECLARATION -- | PRIVATE_TYPE_DECLARATION -- | PRIVATE_EXTENSION_DECLARATION ---------------------------------- -- 3.2.1 Full Type Declaration -- ---------------------------------- -- FULL_TYPE_DECLARATION ::= -- type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART] -- is TYPE_DEFINITION -- [ASPECT_SPECIFICATIONS]; -- | TASK_TYPE_DECLARATION -- | PROTECTED_TYPE_DECLARATION -- The full type declaration node is used only for the first case. The -- second case (concurrent type declaration), is represented directly -- by a task type declaration or a protected type declaration. -- N_Full_Type_Declaration -- Sloc points to TYPE -- Defining_Identifier -- Incomplete_View -- Discriminant_Specifications (set to No_List if none) -- Type_Definition -- Discr_Check_Funcs_Built ---------------------------- -- 3.2.1 Type Definition -- ---------------------------- -- TYPE_DEFINITION ::= -- ENUMERATION_TYPE_DEFINITION | INTEGER_TYPE_DEFINITION -- | REAL_TYPE_DEFINITION | ARRAY_TYPE_DEFINITION -- | RECORD_TYPE_DEFINITION | ACCESS_TYPE_DEFINITION -- | DERIVED_TYPE_DEFINITION | INTERFACE_TYPE_DEFINITION -------------------------------- -- 3.2.2 Subtype Declaration -- -------------------------------- -- SUBTYPE_DECLARATION ::= -- subtype DEFINING_IDENTIFIER is [NULL_EXCLUSION] SUBTYPE_INDICATION -- [ASPECT_SPECIFICATIONS]; -- The subtype indication field is set to Empty for subtypes -- declared in package Standard (Positive, Natural). -- N_Subtype_Declaration -- Sloc points to SUBTYPE -- Defining_Identifier -- Null_Exclusion_Present -- Subtype_Indication -- Generic_Parent_Type (for actual of formal private or derived type) -- Exception_Junk ------------------------------- -- 3.2.2 Subtype Indication -- ------------------------------- -- SUBTYPE_INDICATION ::= SUBTYPE_MARK [CONSTRAINT] -- Note: if no constraint is present, the subtype indication appears -- directly in the tree as a subtype mark. The N_Subtype_Indication -- node is used only if a constraint is present. -- Note: [For Ada 2005 (AI-231)]: Because Ada 2005 extends this rule -- with the null-exclusion part (see AI-231), we had to introduce a new -- attribute in all the parents of subtype_indication nodes to indicate -- if the null-exclusion is present. -- Note: the reason that this node has expression fields is that a -- subtype indication can appear as an operand of a membership test. -- N_Subtype_Indication -- Sloc points to first token of subtype mark -- Subtype_Mark -- Constraint -- Etype -- Must_Not_Freeze -- Note: Depending on context, the Etype is either the entity of the -- Subtype_Mark field, or it is an itype constructed to reify the -- subtype indication. In particular, such itypes are created for a -- subtype indication that appears in an array type declaration. This -- simplifies constraint checking in indexed components. -- For subtype indications that appear in scalar type and subtype -- declarations, the Etype is the entity of the subtype mark. ------------------------- -- 3.2.2 Subtype Mark -- ------------------------- -- SUBTYPE_MARK ::= subtype_NAME ----------------------- -- 3.2.2 Constraint -- ----------------------- -- CONSTRAINT ::= SCALAR_CONSTRAINT | COMPOSITE_CONSTRAINT ------------------------------ -- 3.2.2 Scalar Constraint -- ------------------------------ -- SCALAR_CONSTRAINT ::= -- RANGE_CONSTRAINT | DIGITS_CONSTRAINT | DELTA_CONSTRAINT --------------------------------- -- 3.2.2 Composite Constraint -- --------------------------------- -- COMPOSITE_CONSTRAINT ::= -- INDEX_CONSTRAINT | DISCRIMINANT_CONSTRAINT ------------------------------- -- 3.3.1 Object Declaration -- ------------------------------- -- OBJECT_DECLARATION ::= -- DEFINING_IDENTIFIER_LIST : [aliased] [constant] -- [NULL_EXCLUSION] SUBTYPE_INDICATION [:= EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- | DEFINING_IDENTIFIER_LIST : [aliased] [constant] -- ACCESS_DEFINITION [:= EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- | DEFINING_IDENTIFIER_LIST : [aliased] [constant] -- ARRAY_TYPE_DEFINITION [:= EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- | SINGLE_TASK_DECLARATION -- | SINGLE_PROTECTED_DECLARATION -- Note: aliased is not permitted in Ada 83 mode -- The N_Object_Declaration node is only for the first three cases. -- Single task declaration is handled by P_Task (9.1) -- Single protected declaration is handled by P_protected (9.5) -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive declarations were given with -- identical type definition and expression components. To simplify -- semantic processing, the parser represents a multiple declaration -- case as a sequence of single declarations, using the More_Ids and -- Prev_Ids flags to preserve the original source form as described -- in the section on "Handling of Defining Identifier Lists". -- The flag Has_Init_Expression is set if an initializing expression -- is present. Normally it is set if and only if Expression contains -- a non-empty value, but there is an exception to this. When the -- initializing expression is an aggregate which requires explicit -- assignments, the Expression field gets set to Empty, but this flag -- is still set, so we don't forget we had an initializing expression. -- Note: if a range check is required for the initialization -- expression then the Do_Range_Check flag is set in the Expression, -- with the check being done against the type given by the object -- definition, which is also the Etype of the defining identifier. -- Note: the contents of the Expression field must be ignored (i.e. -- treated as though it were Empty) if No_Initialization is set True. -- Note: the back end places some restrictions on the form of the -- Expression field. If the object being declared is Atomic, then -- the Expression may not have the form of an aggregate (since this -- might cause the back end to generate separate assignments). In this -- case the front end must generate an extra temporary and initialize -- this temporary as required (the temporary itself is not atomic). -- Note: there is no node kind for object definition. Instead, the -- corresponding field holds a subtype indication, an array type -- definition, or (Ada 2005, AI-406) an access definition. -- N_Object_Declaration -- Sloc points to first identifier -- Defining_Identifier -- Aliased_Present -- Constant_Present set if CONSTANT appears -- Null_Exclusion_Present -- Object_Definition subtype indic./array type def./access def. -- Expression (set to Empty if not present) -- Handler_List_Entry -- Corresponding_Generic_Association -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) -- No_Initialization -- Assignment_OK -- Exception_Junk -- Is_Subprogram_Descriptor -- Has_Init_Expression -- Suppress_Assignment_Checks ------------------------------------- -- 3.3.1 Defining Identifier List -- ------------------------------------- -- DEFINING_IDENTIFIER_LIST ::= -- DEFINING_IDENTIFIER {, DEFINING_IDENTIFIER} ------------------------------- -- 3.3.2 Number Declaration -- ------------------------------- -- NUMBER_DECLARATION ::= -- DEFINING_IDENTIFIER_LIST : constant := static_EXPRESSION; -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive declarations were given with -- identical expressions. To simplify semantic processing, the parser -- represents a multiple declaration case as a sequence of single -- declarations, using the More_Ids and Prev_Ids flags to preserve -- the original source form as described in the section on "Handling -- of Defining Identifier Lists". -- N_Number_Declaration -- Sloc points to first identifier -- Defining_Identifier -- Expression -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) ---------------------------------- -- 3.4 Derived Type Definition -- ---------------------------------- -- DERIVED_TYPE_DEFINITION ::= -- [abstract] [limited] new [NULL_EXCLUSION] parent_SUBTYPE_INDICATION -- [[and INTERFACE_LIST] RECORD_EXTENSION_PART] -- Note: ABSTRACT, LIMITED, and record extension part are not permitted -- in Ada 83 mode. -- Note: a record extension part is required if ABSTRACT is present -- N_Derived_Type_Definition -- Sloc points to NEW -- Abstract_Present -- Null_Exclusion_Present (set to False if not present) -- Subtype_Indication -- Record_Extension_Part (set to Empty if not present) -- Limited_Present -- Task_Present set in task interfaces -- Protected_Present set in protected interfaces -- Synchronized_Present set in interfaces -- Interface_List (set to No_List if none) -- Interface_Present set in abstract interfaces -- Note: Task_Present, Protected_Present, Synchronized_Present, -- Interface_List, and Interface_Present are used for abstract -- interfaces (see comments for INTERFACE_TYPE_DEFINITION). --------------------------- -- 3.5 Range Constraint -- --------------------------- -- RANGE_CONSTRAINT ::= range RANGE -- N_Range_Constraint -- Sloc points to RANGE -- Range_Expression ---------------- -- 3.5 Range -- ---------------- -- RANGE ::= -- RANGE_ATTRIBUTE_REFERENCE -- | SIMPLE_EXPRESSION .. SIMPLE_EXPRESSION -- Note: the case of a range given as a range attribute reference -- appears directly in the tree as an attribute reference. -- Note: the field name for a reference to a range is Range_Expression -- rather than Range, because range is a reserved keyword in Ada. -- Note: the reason that this node has expression fields is that a -- range can appear as an operand of a membership test. The Etype -- field is the type of the range (we do NOT construct an implicit -- subtype to represent the range exactly). -- N_Range -- Sloc points to .. -- Low_Bound -- High_Bound -- Cannot_Be_Superflat -- Includes_Infinities -- plus fields for expression -- Note: if the range appears in a context, such as a subtype -- declaration, where range checks are required on one or both of -- the expression fields, then type conversion nodes are inserted -- to represent the required checks. ---------------------------------------- -- 3.5.1 Enumeration Type Definition -- ---------------------------------------- -- ENUMERATION_TYPE_DEFINITION ::= -- (ENUMERATION_LITERAL_SPECIFICATION -- {, ENUMERATION_LITERAL_SPECIFICATION}) -- Note: the Literals field in the node described below is null for -- the case of the standard types CHARACTER and WIDE_CHARACTER, for -- which special processing handles these types as special cases. -- N_Enumeration_Type_Definition -- Sloc points to left parenthesis -- Literals (Empty for CHARACTER or WIDE_CHARACTER) -- End_Label (set to Empty if internally generated record) ---------------------------------------------- -- 3.5.1 Enumeration Literal Specification -- ---------------------------------------------- -- ENUMERATION_LITERAL_SPECIFICATION ::= -- DEFINING_IDENTIFIER | DEFINING_CHARACTER_LITERAL --------------------------------------- -- 3.5.1 Defining Character Literal -- --------------------------------------- -- DEFINING_CHARACTER_LITERAL ::= CHARACTER_LITERAL -- A defining character literal is an entity, which has additional -- fields depending on the setting of the Ekind field. These -- additional fields are defined (and access subprograms declared) -- in package Einfo. -- N_Defining_Character_Literal -- Sloc points to literal -- Chars contains the Name_Id for the identifier -- Next_Entity -- Scope -- Etype ------------------------------------ -- 3.5.4 Integer Type Definition -- ------------------------------------ -- Note: there is an error in this rule in the latest version of the -- grammar, so we have retained the old rule pending clarification. -- INTEGER_TYPE_DEFINITION ::= -- SIGNED_INTEGER_TYPE_DEFINITION -- | MODULAR_TYPE_DEFINITION ------------------------------------------- -- 3.5.4 Signed Integer Type Definition -- ------------------------------------------- -- SIGNED_INTEGER_TYPE_DEFINITION ::= -- range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION -- Note: the Low_Bound and High_Bound fields are set to Empty -- for integer types defined in package Standard. -- N_Signed_Integer_Type_Definition -- Sloc points to RANGE -- Low_Bound -- High_Bound ------------------------------------ -- 3.5.4 Modular Type Definition -- ------------------------------------ -- MODULAR_TYPE_DEFINITION ::= mod static_EXPRESSION -- N_Modular_Type_Definition -- Sloc points to MOD -- Expression --------------------------------- -- 3.5.6 Real Type Definition -- --------------------------------- -- REAL_TYPE_DEFINITION ::= -- FLOATING_POINT_DEFINITION | FIXED_POINT_DEFINITION -------------------------------------- -- 3.5.7 Floating Point Definition -- -------------------------------------- -- FLOATING_POINT_DEFINITION ::= -- digits static_SIMPLE_EXPRESSION [REAL_RANGE_SPECIFICATION] -- Note: The Digits_Expression and Real_Range_Specifications fields -- are set to Empty for floating-point types declared in Standard. -- N_Floating_Point_Definition -- Sloc points to DIGITS -- Digits_Expression -- Real_Range_Specification (set to Empty if not present) ------------------------------------- -- 3.5.7 Real Range Specification -- ------------------------------------- -- REAL_RANGE_SPECIFICATION ::= -- range static_SIMPLE_EXPRESSION .. static_SIMPLE_EXPRESSION -- N_Real_Range_Specification -- Sloc points to RANGE -- Low_Bound -- High_Bound ----------------------------------- -- 3.5.9 Fixed Point Definition -- ----------------------------------- -- FIXED_POINT_DEFINITION ::= -- ORDINARY_FIXED_POINT_DEFINITION | DECIMAL_FIXED_POINT_DEFINITION -------------------------------------------- -- 3.5.9 Ordinary Fixed Point Definition -- -------------------------------------------- -- ORDINARY_FIXED_POINT_DEFINITION ::= -- delta static_EXPRESSION REAL_RANGE_SPECIFICATION -- Note: In Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION -- N_Ordinary_Fixed_Point_Definition -- Sloc points to DELTA -- Delta_Expression -- Real_Range_Specification ------------------------------------------- -- 3.5.9 Decimal Fixed Point Definition -- ------------------------------------------- -- DECIMAL_FIXED_POINT_DEFINITION ::= -- delta static_EXPRESSION -- digits static_EXPRESSION [REAL_RANGE_SPECIFICATION] -- Note: decimal types are not permitted in Ada 83 mode -- N_Decimal_Fixed_Point_Definition -- Sloc points to DELTA -- Delta_Expression -- Digits_Expression -- Real_Range_Specification (set to Empty if not present) ------------------------------ -- 3.5.9 Digits Constraint -- ------------------------------ -- DIGITS_CONSTRAINT ::= -- digits static_EXPRESSION [RANGE_CONSTRAINT] -- Note: in Ada 83, the EXPRESSION must be a SIMPLE_EXPRESSION -- Note: in Ada 95, reduced accuracy subtypes are obsolescent -- N_Digits_Constraint -- Sloc points to DIGITS -- Digits_Expression -- Range_Constraint (set to Empty if not present) -------------------------------- -- 3.6 Array Type Definition -- -------------------------------- -- ARRAY_TYPE_DEFINITION ::= -- UNCONSTRAINED_ARRAY_DEFINITION | CONSTRAINED_ARRAY_DEFINITION ----------------------------------------- -- 3.6 Unconstrained Array Definition -- ----------------------------------------- -- UNCONSTRAINED_ARRAY_DEFINITION ::= -- array (INDEX_SUBTYPE_DEFINITION {, INDEX_SUBTYPE_DEFINITION}) of -- COMPONENT_DEFINITION -- Note: dimensionality of array is indicated by number of entries in -- the Subtype_Marks list, which has one entry for each dimension. -- N_Unconstrained_Array_Definition -- Sloc points to ARRAY -- Subtype_Marks -- Component_Definition ----------------------------------- -- 3.6 Index Subtype Definition -- ----------------------------------- -- INDEX_SUBTYPE_DEFINITION ::= SUBTYPE_MARK range <> -- There is no explicit node in the tree for an index subtype -- definition since the N_Unconstrained_Array_Definition node -- incorporates the type marks which appear in this context. --------------------------------------- -- 3.6 Constrained Array Definition -- --------------------------------------- -- CONSTRAINED_ARRAY_DEFINITION ::= -- array (DISCRETE_SUBTYPE_DEFINITION -- {, DISCRETE_SUBTYPE_DEFINITION}) -- of COMPONENT_DEFINITION -- Note: dimensionality of array is indicated by number of entries -- in the Discrete_Subtype_Definitions list, which has one entry -- for each dimension. -- N_Constrained_Array_Definition -- Sloc points to ARRAY -- Discrete_Subtype_Definitions -- Component_Definition -- Note: although the language allows the full syntax for discrete -- subtype definitions (i.e. a discrete subtype indication or a range), -- in the generated tree, we always rewrite these as N_Range nodes. -------------------------------------- -- 3.6 Discrete Subtype Definition -- -------------------------------------- -- DISCRETE_SUBTYPE_DEFINITION ::= -- discrete_SUBTYPE_INDICATION | RANGE ------------------------------- -- 3.6 Component Definition -- ------------------------------- -- COMPONENT_DEFINITION ::= -- [aliased] [NULL_EXCLUSION] SUBTYPE_INDICATION | ACCESS_DEFINITION -- Note: although the syntax does not permit a component definition to -- be an anonymous array (and the parser will diagnose such an attempt -- with an appropriate message), it is possible for anonymous arrays -- to appear as component definitions. The semantics and back end handle -- this case properly, and the expander in fact generates such cases. -- Access_Definition is an optional field that gives support to -- Ada 2005 (AI-230). The parser generates nodes that have either the -- Subtype_Indication field or else the Access_Definition field. -- N_Component_Definition -- Sloc points to ALIASED, ACCESS, or to first token of subtype mark -- Aliased_Present -- Null_Exclusion_Present -- Subtype_Indication (set to Empty if not present) -- Access_Definition (set to Empty if not present) ----------------------------- -- 3.6.1 Index Constraint -- ----------------------------- -- INDEX_CONSTRAINT ::= (DISCRETE_RANGE {, DISCRETE_RANGE}) -- It is not in general possible to distinguish between discriminant -- constraints and index constraints at parse time, since a simple -- name could be either the subtype mark of a discrete range, or an -- expression in a discriminant association with no name. Either -- entry appears simply as the name, and the semantic parse must -- distinguish between the two cases. Thus we use a common tree -- node format for both of these constraint types. -- See Discriminant_Constraint for format of node --------------------------- -- 3.6.1 Discrete Range -- --------------------------- -- DISCRETE_RANGE ::= discrete_SUBTYPE_INDICATION | RANGE ---------------------------- -- 3.7 Discriminant Part -- ---------------------------- -- DISCRIMINANT_PART ::= -- UNKNOWN_DISCRIMINANT_PART | KNOWN_DISCRIMINANT_PART ------------------------------------ -- 3.7 Unknown Discriminant Part -- ------------------------------------ -- UNKNOWN_DISCRIMINANT_PART ::= (<>) -- Note: unknown discriminant parts are not permitted in Ada 83 mode -- There is no explicit node in the tree for an unknown discriminant -- part. Instead the Unknown_Discriminants_Present flag is set in the -- parent node. ---------------------------------- -- 3.7 Known Discriminant Part -- ---------------------------------- -- KNOWN_DISCRIMINANT_PART ::= -- (DISCRIMINANT_SPECIFICATION {; DISCRIMINANT_SPECIFICATION}) ------------------------------------- -- 3.7 Discriminant Specification -- ------------------------------------- -- DISCRIMINANT_SPECIFICATION ::= -- DEFINING_IDENTIFIER_LIST : [NULL_EXCLUSION] SUBTYPE_MARK -- [:= DEFAULT_EXPRESSION] -- | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION -- [:= DEFAULT_EXPRESSION] -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive specifications were given with -- identical type definition and expression components. To simplify -- semantic processing, the parser represents a multiple declaration -- case as a sequence of single specifications, using the More_Ids and -- Prev_Ids flags to preserve the original source form as described -- in the section on "Handling of Defining Identifier Lists". -- N_Discriminant_Specification -- Sloc points to first identifier -- Defining_Identifier -- Null_Exclusion_Present -- Discriminant_Type subtype mark or access parameter definition -- Expression (set to Empty if no default expression) -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) ----------------------------- -- 3.7 Default Expression -- ----------------------------- -- DEFAULT_EXPRESSION ::= EXPRESSION ------------------------------------ -- 3.7.1 Discriminant Constraint -- ------------------------------------ -- DISCRIMINANT_CONSTRAINT ::= -- (DISCRIMINANT_ASSOCIATION {, DISCRIMINANT_ASSOCIATION}) -- It is not in general possible to distinguish between discriminant -- constraints and index constraints at parse time, since a simple -- name could be either the subtype mark of a discrete range, or an -- expression in a discriminant association with no name. Either -- entry appears simply as the name, and the semantic parse must -- distinguish between the two cases. Thus we use a common tree -- node format for both of these constraint types. -- N_Index_Or_Discriminant_Constraint -- Sloc points to left paren -- Constraints points to list of discrete ranges or -- discriminant associations ------------------------------------- -- 3.7.1 Discriminant Association -- ------------------------------------- -- DISCRIMINANT_ASSOCIATION ::= -- [discriminant_SELECTOR_NAME -- {| discriminant_SELECTOR_NAME} =>] EXPRESSION -- Note: a discriminant association that has no selector name list -- appears directly as an expression in the tree. -- N_Discriminant_Association -- Sloc points to first token of discriminant association -- Selector_Names (always non-empty, since if no selector -- names are present, this node is not used, see comment above) -- Expression --------------------------------- -- 3.8 Record Type Definition -- --------------------------------- -- RECORD_TYPE_DEFINITION ::= -- [[abstract] tagged] [limited] RECORD_DEFINITION -- Note: ABSTRACT, TAGGED, LIMITED are not permitted in Ada 83 mode -- There is no explicit node in the tree for a record type definition. -- Instead the flags for Tagged_Present and Limited_Present appear in -- the N_Record_Definition node for a record definition appearing in -- the context of a record type definition. ---------------------------- -- 3.8 Record Definition -- ---------------------------- -- RECORD_DEFINITION ::= -- record -- COMPONENT_LIST -- end record -- | null record -- Note: the Abstract_Present, Tagged_Present, and Limited_Present -- flags appear only for a record definition appearing in a record -- type definition. -- Note: the NULL RECORD case is not permitted in Ada 83 -- N_Record_Definition -- Sloc points to RECORD or NULL -- End_Label (set to Empty if internally generated record) -- Abstract_Present -- Tagged_Present -- Limited_Present -- Component_List empty in null record case -- Null_Present set in null record case -- Task_Present set in task interfaces -- Protected_Present set in protected interfaces -- Synchronized_Present set in interfaces -- Interface_Present set in abstract interfaces -- Interface_List (set to No_List if none) -- Note: Task_Present, Protected_Present, Synchronized _Present, -- Interface_List and Interface_Present are used for abstract -- interfaces (see comments for INTERFACE_TYPE_DEFINITION). ------------------------- -- 3.8 Component List -- ------------------------- -- COMPONENT_LIST ::= -- COMPONENT_ITEM {COMPONENT_ITEM} -- | {COMPONENT_ITEM} VARIANT_PART -- | null; -- N_Component_List -- Sloc points to first token of component list -- Component_Items -- Variant_Part (set to Empty if no variant part) -- Null_Present ------------------------- -- 3.8 Component Item -- ------------------------- -- COMPONENT_ITEM ::= COMPONENT_DECLARATION | REPRESENTATION_CLAUSE -- Note: A component item can also be a pragma, and in the tree -- that is obtained after semantic processing, a component item -- can be an N_Null node resulting from a non-recognized pragma. -------------------------------- -- 3.8 Component Declaration -- -------------------------------- -- COMPONENT_DECLARATION ::= -- DEFINING_IDENTIFIER_LIST : COMPONENT_DEFINITION -- [:= DEFAULT_EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- Note: although the syntax does not permit a component definition to -- be an anonymous array (and the parser will diagnose such an attempt -- with an appropriate message), it is possible for anonymous arrays -- to appear as component definitions. The semantics and back end handle -- this case properly, and the expander in fact generates such cases. -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive declarations were given with the -- same component definition and expression components. To simplify -- semantic processing, the parser represents a multiple declaration -- case as a sequence of single declarations, using the More_Ids and -- Prev_Ids flags to preserve the original source form as described -- in the section on "Handling of Defining Identifier Lists". -- N_Component_Declaration -- Sloc points to first identifier -- Defining_Identifier -- Component_Definition -- Expression (set to Empty if no default expression) -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) ------------------------- -- 3.8.1 Variant Part -- ------------------------- -- VARIANT_PART ::= -- case discriminant_DIRECT_NAME is -- VARIANT {VARIANT} -- end case; -- Note: the variants list can contain pragmas as well as variants. -- In a properly formed program there is at least one variant. -- N_Variant_Part -- Sloc points to CASE -- Name -- Variants -------------------- -- 3.8.1 Variant -- -------------------- -- VARIANT ::= -- when DISCRETE_CHOICE_LIST => -- COMPONENT_LIST -- N_Variant -- Sloc points to WHEN -- Discrete_Choices -- Component_List -- Enclosing_Variant -- Present_Expr -- Dcheck_Function -- Has_SP_Choice -- Note: in the list of Discrete_Choices, the tree passed to the back -- end does not have choice entries corresponding to names of statically -- predicated subtypes. Such entries are always expanded out to the list -- of equivalent values or ranges. --------------------------------- -- 3.8.1 Discrete Choice List -- --------------------------------- -- DISCRETE_CHOICE_LIST ::= DISCRETE_CHOICE {| DISCRETE_CHOICE} ---------------------------- -- 3.8.1 Discrete Choice -- ---------------------------- -- DISCRETE_CHOICE ::= EXPRESSION | DISCRETE_RANGE | others -- Note: in Ada 83 mode, the expression must be a simple expression -- The only choice that appears explicitly is the OTHERS choice, as -- defined here. Other cases of discrete choice (expression and -- discrete range) appear directly. This production is also used -- for the OTHERS possibility of an exception choice. -- Note: in accordance with the syntax, the parser does not check that -- OTHERS appears at the end on its own in a choice list context. This -- is a semantic check. -- N_Others_Choice -- Sloc points to OTHERS -- Others_Discrete_Choices -- All_Others ---------------------------------- -- 3.9.1 Record Extension Part -- ---------------------------------- -- RECORD_EXTENSION_PART ::= with RECORD_DEFINITION -- Note: record extension parts are not permitted in Ada 83 mode -------------------------------------- -- 3.9.4 Interface Type Definition -- -------------------------------------- -- INTERFACE_TYPE_DEFINITION ::= -- [limited | task | protected | synchronized] -- interface [interface_list] -- Note: Interfaces are implemented with N_Record_Definition and -- N_Derived_Type_Definition nodes because most of the support -- for the analysis of abstract types has been reused to -- analyze abstract interfaces. ---------------------------------- -- 3.10 Access Type Definition -- ---------------------------------- -- ACCESS_TYPE_DEFINITION ::= -- ACCESS_TO_OBJECT_DEFINITION -- | ACCESS_TO_SUBPROGRAM_DEFINITION -------------------------- -- 3.10 Null Exclusion -- -------------------------- -- NULL_EXCLUSION ::= not null --------------------------------------- -- 3.10 Access To Object Definition -- --------------------------------------- -- ACCESS_TO_OBJECT_DEFINITION ::= -- [NULL_EXCLUSION] access [GENERAL_ACCESS_MODIFIER] -- SUBTYPE_INDICATION -- N_Access_To_Object_Definition -- Sloc points to ACCESS -- All_Present -- Null_Exclusion_Present -- Null_Excluding_Subtype -- Subtype_Indication -- Constant_Present ----------------------------------- -- 3.10 General Access Modifier -- ----------------------------------- -- GENERAL_ACCESS_MODIFIER ::= all | constant -- Note: general access modifiers are not permitted in Ada 83 mode -- There is no explicit node in the tree for general access modifier. -- Instead the All_Present or Constant_Present flags are set in the -- parent node. ------------------------------------------- -- 3.10 Access To Subprogram Definition -- ------------------------------------------- -- ACCESS_TO_SUBPROGRAM_DEFINITION -- [NULL_EXCLUSION] access [protected] procedure PARAMETER_PROFILE -- | [NULL_EXCLUSION] access [protected] function -- PARAMETER_AND_RESULT_PROFILE -- Note: access to subprograms are not permitted in Ada 83 mode -- N_Access_Function_Definition -- Sloc points to ACCESS -- Null_Exclusion_Present -- Null_Exclusion_In_Return_Present -- Protected_Present -- Parameter_Specifications (set to No_List if no formal part) -- Result_Definition result subtype (subtype mark or access def) -- N_Access_Procedure_Definition -- Sloc points to ACCESS -- Null_Exclusion_Present -- Protected_Present -- Parameter_Specifications (set to No_List if no formal part) ----------------------------- -- 3.10 Access Definition -- ----------------------------- -- ACCESS_DEFINITION ::= -- [NULL_EXCLUSION] access [GENERAL_ACCESS_MODIFIER] SUBTYPE_MARK -- | ACCESS_TO_SUBPROGRAM_DEFINITION -- Note: access to subprograms are an Ada 2005 (AI-254) extension -- N_Access_Definition -- Sloc points to ACCESS -- Null_Exclusion_Present -- All_Present -- Constant_Present -- Subtype_Mark -- Access_To_Subprogram_Definition (set to Empty if not present) ----------------------------------------- -- 3.10.1 Incomplete Type Declaration -- ----------------------------------------- -- INCOMPLETE_TYPE_DECLARATION ::= -- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] [IS TAGGED]; -- N_Incomplete_Type_Declaration -- Sloc points to TYPE -- Defining_Identifier -- Discriminant_Specifications (set to No_List if no -- discriminant part, or if the discriminant part is an -- unknown discriminant part) -- Premature_Use used for improved diagnostics. -- Unknown_Discriminants_Present set if (<>) discriminant -- Tagged_Present ---------------------------- -- 3.11 Declarative Part -- ---------------------------- -- DECLARATIVE_PART ::= {DECLARATIVE_ITEM} -- Note: although the parser enforces the syntactic requirement that -- a declarative part can contain only declarations, the semantic -- processing may add statements to the list of actions in a -- declarative part, so the code generator should be prepared -- to accept a statement in this position. ---------------------------- -- 3.11 Declarative Item -- ---------------------------- -- DECLARATIVE_ITEM ::= BASIC_DECLARATIVE_ITEM | BODY ---------------------------------- -- 3.11 Basic Declarative Item -- ---------------------------------- -- BASIC_DECLARATIVE_ITEM ::= -- BASIC_DECLARATION | REPRESENTATION_CLAUSE | USE_CLAUSE ---------------- -- 3.11 Body -- ---------------- -- BODY ::= PROPER_BODY | BODY_STUB ----------------------- -- 3.11 Proper Body -- ----------------------- -- PROPER_BODY ::= -- SUBPROGRAM_BODY | PACKAGE_BODY | TASK_BODY | PROTECTED_BODY --------------- -- 4.1 Name -- --------------- -- NAME ::= -- DIRECT_NAME | EXPLICIT_DEREFERENCE -- | INDEXED_COMPONENT | SLICE -- | SELECTED_COMPONENT | ATTRIBUTE_REFERENCE -- | TYPE_CONVERSION | FUNCTION_CALL -- | CHARACTER_LITERAL ---------------------- -- 4.1 Direct Name -- ---------------------- -- DIRECT_NAME ::= IDENTIFIER | OPERATOR_SYMBOL ----------------- -- 4.1 Prefix -- ----------------- -- PREFIX ::= NAME | IMPLICIT_DEREFERENCE ------------------------------- -- 4.1 Explicit Dereference -- ------------------------------- -- EXPLICIT_DEREFERENCE ::= NAME . all -- N_Explicit_Dereference -- Sloc points to ALL -- Prefix -- Actual_Designated_Subtype -- Has_Dereference_Action -- Atomic_Sync_Required -- plus fields for expression ------------------------------- -- 4.1 Implicit Dereference -- ------------------------------- -- IMPLICIT_DEREFERENCE ::= NAME ------------------------------ -- 4.1.1 Indexed Component -- ------------------------------ -- INDEXED_COMPONENT ::= PREFIX (EXPRESSION {, EXPRESSION}) -- Note: the parser may generate this node in some situations where it -- should be a function call. The semantic pass must correct this -- misidentification (which is inevitable at the parser level). -- N_Indexed_Component -- Sloc contains a copy of the Sloc value of the Prefix -- Prefix -- Expressions -- Generalized_Indexing -- Atomic_Sync_Required -- plus fields for expression -- Note: if any of the subscripts requires a range check, then the -- Do_Range_Check flag is set on the corresponding expression, with -- the index type being determined from the type of the Prefix, which -- references the array being indexed. -- Note: in a fully analyzed and expanded indexed component node, and -- hence in any such node that gigi sees, if the prefix is an access -- type, then an explicit dereference operation has been inserted. ------------------ -- 4.1.2 Slice -- ------------------ -- SLICE ::= PREFIX (DISCRETE_RANGE) -- Note: an implicit subtype is created to describe the resulting -- type, so that the bounds of this type are the bounds of the slice. -- N_Slice -- Sloc points to first token of prefix -- Prefix -- Discrete_Range -- plus fields for expression ------------------------------- -- 4.1.3 Selected Component -- ------------------------------- -- SELECTED_COMPONENT ::= PREFIX . SELECTOR_NAME -- Note: selected components that are semantically expanded names get -- changed during semantic processing into the separate N_Expanded_Name -- node. See description of this node in the section on semantic nodes. -- N_Selected_Component -- Sloc points to the period -- Prefix -- Selector_Name -- Associated_Node -- Do_Discriminant_Check -- Is_In_Discriminant_Check -- Atomic_Sync_Required -- Is_Prefixed_Call -- plus fields for expression -------------------------- -- 4.1.3 Selector Name -- -------------------------- -- SELECTOR_NAME ::= IDENTIFIER | CHARACTER_LITERAL | OPERATOR_SYMBOL -------------------------------- -- 4.1.4 Attribute Reference -- -------------------------------- -- ATTRIBUTE_REFERENCE ::= PREFIX ' ATTRIBUTE_DESIGNATOR -- Note: the syntax is quite ambiguous at this point. Consider: -- A'Length (X) X is part of the attribute designator -- A'Pos (X) X is an explicit actual parameter of function A'Pos -- A'Class (X) X is the expression of a type conversion -- It would be possible for the parser to distinguish these cases -- by looking at the attribute identifier. However, that would mean -- more work in introducing new implementation defined attributes, -- and also it would mean that special processing for attributes -- would be scattered around, instead of being centralized in the -- semantic routine that handles an N_Attribute_Reference node. -- Consequently, the parser in all the above cases stores the -- expression (X in these examples) as a single element list in -- in the Expressions field of the N_Attribute_Reference node. -- Similarly, for attributes like Max which take two arguments, -- we store the two arguments as a two element list in the -- Expressions field. Of course it is clear at parse time that -- this case is really a function call with an attribute as the -- prefix, but it turns out to be convenient to handle the two -- argument case in a similar manner to the one argument case, -- and indeed in general the parser will accept any number of -- expressions in this position and store them as a list in the -- attribute reference node. This allows for future addition of -- attributes that take more than two arguments. -- Note: named associates are not permitted in function calls where -- the function is an attribute (see RM 6.4(3)) so it is legitimate -- to skip the normal subprogram argument processing. -- Note: for the attributes whose designators are technically keywords, -- i.e. digits, access, delta, range, the Attribute_Name field contains -- the corresponding name, even though no identifier is involved. -- Note: the generated code may contain stream attributes applied to -- limited types for which no stream routines exist officially. In such -- case, the result is to use the stream attribute for the underlying -- full type, or in the case of a protected type, the components -- (including any discriminants) are merely streamed in order. -- See Exp_Attr for a complete description of which attributes are -- passed onto Gigi, and which are handled entirely by the front end. -- Gigi restriction: For the Pos attribute, the prefix cannot be -- a non-standard enumeration type or a nonzero/zero semantics -- boolean type, so the value is simply the stored representation. -- Gigi requirement: For the Mechanism_Code attribute, if the prefix -- references a subprogram that is a renaming, then the front end must -- rewrite the attribute to refer directly to the renamed entity. -- Note: syntactically the prefix of an attribute reference must be a -- name, and this (somewhat artificial) requirement is enforced by the -- parser. However, for many attributes, such as 'Valid, it is quite -- reasonable to apply the attribute to any value, and hence to any -- expression. Internally in the tree, the prefix is an expression which -- does not have to be a name, and this is handled fine by the semantic -- analysis and expansion, and back ends. This arises for the case of -- attribute references built by the expander (e.g. 'Valid for the case -- of an implicit validity check). -- Note: In generated code, the Address and Unrestricted_Access -- attributes can be applied to any expression, and the meaning is -- to create an object containing the value (the object is in the -- current stack frame), and pass the address of this value. If the -- Must_Be_Byte_Aligned flag is set, then the object whose address -- is taken must be on a byte (storage unit) boundary, and if it is -- not (or may not be), then the generated code must create a copy -- that is byte aligned, and pass the address of this copy. -- N_Attribute_Reference -- Sloc points to apostrophe -- Prefix (general expression, see note above) -- Attribute_Name identifier name from attribute designator -- Expressions (set to No_List if no associated expressions) -- Entity used if the attribute yields a type -- Associated_Node -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Header_Size_Added -- Redundant_Use -- Must_Be_Byte_Aligned -- plus fields for expression -- Note: in Modify_Tree_For_C mode, Max and Min attributes are expanded -- into equivalent if expressions, properly taking care of side effects. --------------------------------- -- 4.1.4 Attribute Designator -- --------------------------------- -- ATTRIBUTE_DESIGNATOR ::= -- IDENTIFIER [(static_EXPRESSION)] -- | access | delta | digits -- There is no explicit node in the tree for an attribute designator. -- Instead the Attribute_Name and Expressions fields of the parent -- node (N_Attribute_Reference node) hold the information. -- Note: if ACCESS, DELTA, or DIGITS appears in an attribute -- designator, then they are treated as identifiers internally -- rather than the keywords of the same name. -------------------------------------- -- 4.1.4 Range Attribute Reference -- -------------------------------------- -- RANGE_ATTRIBUTE_REFERENCE ::= PREFIX ' RANGE_ATTRIBUTE_DESIGNATOR -- A range attribute reference is represented in the tree using the -- normal N_Attribute_Reference node. --------------------------------------- -- 4.1.4 Range Attribute Designator -- --------------------------------------- -- RANGE_ATTRIBUTE_DESIGNATOR ::= Range [(static_EXPRESSION)] -- A range attribute designator is represented in the tree using the -- normal N_Attribute_Reference node. -------------------- -- 4.3 Aggregate -- -------------------- -- AGGREGATE ::= -- RECORD_AGGREGATE | EXTENSION_AGGREGATE | ARRAY_AGGREGATE ----------------------------- -- 4.3.1 Record Aggregate -- ----------------------------- -- RECORD_AGGREGATE ::= (RECORD_COMPONENT_ASSOCIATION_LIST) -- N_Aggregate -- Sloc points to left parenthesis -- Expressions (set to No_List if none or null record case) -- Component_Associations (set to No_List if none) -- Null_Record_Present -- Aggregate_Bounds -- Associated_Node -- Compile_Time_Known_Aggregate -- Expansion_Delayed -- Has_Self_Reference -- Is_Enum_Array_Aggregate -- Is_Homogeneous_Aggregate -- Is_Parenthesis_Aggregate -- plus fields for expression -- Note: this structure is used for both record and array aggregates -- since the two cases are not separable by the parser. The parser -- makes no attempt to enforce consistency here, so it is up to the -- semantic phase to make sure that the aggregate is consistent (i.e. -- that it is not a "half-and-half" case that mixes record and array -- syntax). In particular, for a record aggregate, the expressions -- field will be set if there are positional associations. -- Note: N_Aggregate is not used for all aggregates; in particular, -- there is a separate node kind for extension aggregates. -- Note: gigi/gcc can handle array aggregates correctly providing that -- they are entirely positional, and the array subtype involved has a -- known at compile time length and is not bit packed, or a convention -- Fortran array with more than one dimension. If these conditions -- are not met, then the front end must translate the aggregate into -- an appropriate set of assignments into a temporary. -- Note: for the record aggregate case, gigi/gcc can handle most cases -- of record aggregates, including those for packed, and rep-claused -- records, and also variant records, providing that there are no -- variable length fields whose size is not known at compile time, -- and providing that the aggregate is presented in fully named form. -- The other situation in which array aggregates and record aggregates -- cannot be passed to the back end is if assignment to one or more -- components itself needs expansion, e.g. in the case of an assignment -- of an object of a controlled type. In such cases, the front end -- must expand the aggregate to a series of assignments, and apply -- the required expansion to the individual assignment statements. ---------------------------------------------- -- 4.3.1 Record Component Association List -- ---------------------------------------------- -- RECORD_COMPONENT_ASSOCIATION_LIST ::= -- RECORD_COMPONENT_ASSOCIATION {, RECORD_COMPONENT_ASSOCIATION} -- | null record -- There is no explicit node in the tree for a record component -- association list. Instead the Null_Record_Present flag is set in -- the parent node for the NULL RECORD case. ------------------------------------------------------ -- 4.3.1 Record Component Association (also 4.3.3) -- ------------------------------------------------------ -- RECORD_COMPONENT_ASSOCIATION ::= -- [COMPONENT_CHOICE_LIST =>] EXPRESSION -- N_Component_Association -- Sloc points to first selector name -- Choices -- Expression (empty if Box_Present) -- Loop_Actions -- Box_Present -- Inherited_Discriminant -- Binding_Chars -- Note: this structure is used for both record component associations -- and array component associations, since the two cases aren't always -- separable by the parser. The choices list may represent either a -- list of selector names in the record aggregate case, or a list of -- discrete choices in the array aggregate case or an N_Others_Choice -- node (which appears as a singleton list). Box_Present gives support -- to Ada 2005 (AI-287). Binding_Chars is only set if GNAT extensions -- are enabled and the given component association occurs within a -- choice_expression; in this case, it is the Name_Id, if any, specified -- via either of two syntactic forms: "Foo => Bar is Abc" or -- "Foo => ". ---------------------------------- -- 4.3.1 Component Choice List -- ---------------------------------- -- COMPONENT_CHOICE_LIST ::= -- component_SELECTOR_NAME {| component_SELECTOR_NAME} -- | others -- The entries of a component choice list appear in the Choices list of -- the associated N_Component_Association, as either selector names, or -- as an N_Others_Choice node. -------------------------------- -- 4.3.2 Extension Aggregate -- -------------------------------- -- EXTENSION_AGGREGATE ::= -- (ANCESTOR_PART with RECORD_COMPONENT_ASSOCIATION_LIST) -- Note: extension aggregates are not permitted in Ada 83 mode -- N_Extension_Aggregate -- Sloc points to left parenthesis -- Ancestor_Part -- Associated_Node -- Expressions (set to No_List if none or null record case) -- Component_Associations (set to No_List if none) -- Null_Record_Present -- Expansion_Delayed -- Has_Self_Reference -- plus fields for expression -------------------------- -- 4.3.2 Ancestor Part -- -------------------------- -- ANCESTOR_PART ::= EXPRESSION | SUBTYPE_MARK ---------------------------- -- 4.3.3 Array Aggregate -- ---------------------------- -- ARRAY_AGGREGATE ::= -- POSITIONAL_ARRAY_AGGREGATE | NAMED_ARRAY_AGGREGATE --------------------------------------- -- 4.3.3 Positional Array Aggregate -- --------------------------------------- -- POSITIONAL_ARRAY_AGGREGATE ::= -- (EXPRESSION, EXPRESSION {, EXPRESSION}) -- | (EXPRESSION {, EXPRESSION}, others => EXPRESSION) -- See Record_Aggregate (4.3.1) for node structure ---------------------------------- -- 4.3.3 Named Array Aggregate -- ---------------------------------- -- NAMED_ARRAY_AGGREGATE ::= -- (ARRAY_COMPONENT_ASSOCIATION {, ARRAY_COMPONENT_ASSOCIATION}) -- See Record_Aggregate (4.3.1) for node structure ---------------------------------------- -- 4.3.3 Array Component Association -- ---------------------------------------- -- ARRAY_COMPONENT_ASSOCIATION ::= -- DISCRETE_CHOICE_LIST => EXPRESSION -- | ITERATED_COMPONENT_ASSOCIATION -- See Record_Component_Association (4.3.1) for node structure -- The iterated_component_association is introduced into the -- Corrigendum of Ada_2012 by AI12-061. ------------------------------------------ -- 4.3.3 Iterated component Association -- ------------------------------------------ -- ITERATED_COMPONENT_ASSOCIATION ::= -- for DEFINING_IDENTIFIER in DISCRETE_CHOICE_LIST => EXPRESSION -- for ITERATOR_SPECIFICATION => EXPRESSION -- At most one of (Defining_Identifier, Iterator_Specification) -- is present at a time, in which case the other one is empty. -- N_Iterated_Component_Association -- Sloc points to FOR -- Defining_Identifier -- Iterator_Specification -- Expression -- Discrete_Choices -- Loop_Actions -- Box_Present -- Note that Box_Present is always False, but it is intentionally added -- for completeness. ---------------------------- -- 4.3.4 Delta Aggregate -- ---------------------------- -- N_Delta_Aggregate -- Sloc points to left parenthesis -- Expression -- Component_Associations -- Etype --------------------------------- -- 3.4.5 Container_Aggregates -- --------------------------------- -- ITERATED_ELEMENT_ASSOCIATION ::= -- for LOOP_PARAMETER_SPECIFICATION[ use KEY_EXPRESSION] => EXPRESSION -- | for ITERATOR_SPECIFICATION[ use KEY_EXPRESSION] => EXPRESSION -- N_Iterated_Element_Association -- Key_Expression -- Iterator_Specification -- Expression -- Loop_Parameter_Specification -- Loop_Actions -- Box_Present -- Exactly one of Iterator_Specification or Loop_Parameter_ -- specification is present. If the Key_Expression is absent, -- the construct is parsed as an Iterated_Component_Association, -- and legality checks are performed during semantic analysis. -- Both iterated associations are Ada 2022 features that are -- expanded during aggregate construction, and do not appear in -- expanded code. -------------------------------------------------- -- 4.4 Expression/Relation/Term/Factor/Primary -- -------------------------------------------------- -- EXPRESSION ::= -- RELATION {LOGICAL_OPERATOR RELATION} -- CHOICE_EXPRESSION ::= -- CHOICE_RELATION {LOGICAL_OPERATOR CHOICE_RELATION} -- CHOICE_RELATION ::= -- SIMPLE_EXPRESSION [RELATIONAL_OPERATOR SIMPLE_EXPRESSION] -- RELATION ::= -- SIMPLE_EXPRESSION [not] in MEMBERSHIP_CHOICE_LIST -- | RAISE_EXPRESSION -- MEMBERSHIP_CHOICE_LIST ::= -- MEMBERSHIP_CHOICE {'|' MEMBERSHIP CHOICE} -- MEMBERSHIP_CHOICE ::= -- CHOICE_EXPRESSION | RANGE | SUBTYPE_MARK -- LOGICAL_OPERATOR ::= and | and then | or | or else | xor -- SIMPLE_EXPRESSION ::= -- [UNARY_ADDING_OPERATOR] TERM {BINARY_ADDING_OPERATOR TERM} -- TERM ::= FACTOR {MULTIPLYING_OPERATOR FACTOR} -- FACTOR ::= PRIMARY [** PRIMARY] | abs PRIMARY | not PRIMARY -- No nodes are generated for any of these constructs. Instead, the -- node for the operator appears directly. When we refer to an -- expression in this description, we mean any of the possible -- constituent components of an expression (e.g. identifier is -- an example of an expression). -- Note: the above syntax is that Ada 2012 syntax which restricts -- choice relations to simple expressions to avoid ambiguities in -- some contexts with set membership notation. It has been decided -- that in retrospect, the Ada 95 change allowing general expressions -- in this context was a mistake, so we have reverted to the above -- syntax in Ada 95 and Ada 2005 modes (the restriction to simple -- expressions was there in Ada 83 from the start). ------------------ -- 4.4 Primary -- ------------------ -- PRIMARY ::= -- NUMERIC_LITERAL | null -- | STRING_LITERAL | AGGREGATE -- | NAME | QUALIFIED_EXPRESSION -- | ALLOCATOR | (EXPRESSION) -- Usually there is no explicit node in the tree for primary. Instead -- the constituent (e.g. AGGREGATE) appears directly. There are two -- exceptions. First, there is an explicit node for a null primary. -- N_Null -- Sloc points to NULL -- plus fields for expression -- Second, the case of (EXPRESSION) is handled specially. Ada requires -- that the parser keep track of which subexpressions are enclosed -- in parentheses, and how many levels of parentheses are used. This -- information is required for optimization purposes, and also for -- some semantic checks (e.g. (((1))) in a procedure spec does not -- conform with ((((1)))) in the body). -- The parentheses are recorded by keeping a Paren_Count field in every -- subexpression node (it is actually present in all nodes, but only -- used in subexpression nodes). This count records the number of -- levels of parentheses. If the number of levels in the source exceeds -- the maximum accommodated by this count, then the count is simply left -- at the maximum value. This means that there are some pathological -- cases of failure to detect conformance failures (e.g. an expression -- with 500 levels of parens will conform with one with 501 levels), -- but we do not need to lose sleep over this. -- Historical note: in versions of GNAT prior to 1.75, there was a node -- type N_Parenthesized_Expression used to accurately record unlimited -- numbers of levels of parentheses. However, it turned out to be a -- real nuisance to have to take into account the possible presence of -- this node during semantic analysis, since basically parentheses have -- zero relevance to semantic analysis. -- Note: the level of parentheses always present in things like -- aggregates does not count, only the parentheses in the primary -- (EXPRESSION) affect the setting of the Paren_Count field. -- 2nd Note: the contents of the Expression field must be ignored (i.e. -- treated as though it were Empty) if No_Initialization is set True. -------------------------------------- -- 4.5 Short-Circuit Control Forms -- -------------------------------------- -- EXPRESSION ::= -- RELATION {and then RELATION} | RELATION {or else RELATION} -- Gigi restriction: For both these control forms, the operand and -- result types are always Standard.Boolean. The expander inserts the -- required conversion operations where needed to ensure this is the -- case. -- N_And_Then -- Sloc points to AND of AND THEN -- Left_Opnd -- Right_Opnd -- Actions -- plus fields for expression -- N_Or_Else -- Sloc points to OR of OR ELSE -- Left_Opnd -- Right_Opnd -- Actions -- plus fields for expression -- Note: The Actions field is used to hold actions associated with -- the right hand operand. These have to be treated specially since -- they are not unconditionally executed. See Insert_Actions for a -- more detailed description of how these actions are handled. --------------------------- -- 4.5 Membership Tests -- --------------------------- -- RELATION ::= -- SIMPLE_EXPRESSION [not] in MEMBERSHIP_CHOICE_LIST -- MEMBERSHIP_CHOICE_LIST ::= -- MEMBERSHIP_CHOICE {'|' MEMBERSHIP CHOICE} -- MEMBERSHIP_CHOICE ::= -- CHOICE_EXPRESSION | RANGE | SUBTYPE_MARK -- Note: although the grammar above allows only a range or a subtype -- mark, the parser in fact will accept any simple expression in place -- of a subtype mark. This means that the semantic analyzer must be able -- to deal with, and diagnose a simple expression other than a name for -- the right operand. This simplifies error recovery in the parser. -- The Alternatives field below is present only if there is more than -- one Membership_Choice present (which is legitimate only in Ada 2012 -- mode) in which case Right_Opnd is Empty, and Alternatives contains -- the list of choices. In the tree passed to the back end, Alternatives -- is always No_List, and Right_Opnd is set (i.e. the expansion circuit -- expands out the complex set membership case using simple membership -- and equality operations). -- Should we rename Alternatives here to Membership_Choices ??? -- N_In -- Sloc points to IN -- Left_Opnd -- Right_Opnd -- Alternatives (set to No_List if only one set alternative) -- No_Minimize_Eliminate -- plus fields for expression -- N_Not_In -- Sloc points to NOT of NOT IN -- Left_Opnd -- Right_Opnd -- Alternatives (set to No_List if only one set alternative) -- No_Minimize_Eliminate -- plus fields for expression -------------------- -- 4.5 Operators -- -------------------- -- LOGICAL_OPERATOR ::= and | or | xor -- RELATIONAL_OPERATOR ::= = | /= | < | <= | > | >= -- BINARY_ADDING_OPERATOR ::= + | - | & -- UNARY_ADDING_OPERATOR ::= + | - -- MULTIPLYING_OPERATOR ::= * | / | mod | rem -- HIGHEST_PRECEDENCE_OPERATOR ::= ** | abs | not -- Gigi restriction: Gigi will never be given * / mod rem nodes with -- fixed-point operands. All handling of smalls for multiplication and -- division is handled by the front end (mod and rem result only from -- expansion). Gigi thus never needs to worry about small values (for -- other operators operating on fixed-point, e.g. addition, the small -- value does not have any semantic effect anyway, these are always -- integer operations). -- Gigi restriction: For all operators taking Boolean operands, the -- type is always Standard.Boolean. The expander inserts the required -- conversion operations where needed to ensure this is the case. -- N_Op_And -- Sloc points to AND -- Do_Length_Check -- plus fields for binary operator -- plus fields for expression -- N_Op_Or -- Sloc points to OR -- Do_Length_Check -- plus fields for binary operator -- plus fields for expression -- N_Op_Xor -- Sloc points to XOR -- Do_Length_Check -- plus fields for binary operator -- plus fields for expression -- N_Op_Eq -- Sloc points to = -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Ne -- Sloc points to /= -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Lt -- Sloc points to < -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Le -- Sloc points to <= -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Gt -- Sloc points to > -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Ge -- Sloc points to >= -- Compare_Type -- plus fields for binary operator -- plus fields for expression -- N_Op_Add -- Sloc points to + (binary) -- plus fields for binary operator -- plus fields for expression -- N_Op_Subtract -- Sloc points to - (binary) -- plus fields for binary operator -- plus fields for expression -- N_Op_Concat -- Sloc points to & -- Is_Component_Left_Opnd -- Is_Component_Right_Opnd -- plus fields for binary operator -- plus fields for expression -- N_Op_Multiply -- Sloc points to * -- Rounded_Result -- plus fields for binary operator -- plus fields for expression -- N_Op_Divide -- Sloc points to / -- Do_Division_Check -- Rounded_Result -- plus fields for binary operator -- plus fields for expression -- N_Op_Mod -- Sloc points to MOD -- Do_Division_Check -- plus fields for binary operator -- plus fields for expression -- N_Op_Rem -- Sloc points to REM -- Do_Division_Check -- plus fields for binary operator -- plus fields for expression -- N_Op_Expon -- Sloc points to ** -- Is_Power_Of_2_For_Shift -- plus fields for binary operator -- plus fields for expression -- N_Op_Plus -- Sloc points to + (unary) -- plus fields for unary operator -- plus fields for expression -- N_Op_Minus -- Sloc points to - (unary) -- plus fields for unary operator -- plus fields for expression -- N_Op_Abs -- Sloc points to ABS -- plus fields for unary operator -- plus fields for expression -- N_Op_Not -- Sloc points to NOT -- plus fields for unary operator -- plus fields for expression -- See also shift operators in section B.2 -- Note on fixed-point operations passed to Gigi: For adding operators, -- the semantics is to treat these simply as integer operations, with -- the small values being ignored (the bounds are already stored in -- units of small, so that constraint checking works as usual). For the -- case of multiply/divide/rem/mod operations, Gigi will never see them. -- Note on equality/inequality tests for records. In the expanded tree, -- record comparisons are always expanded to be a series of component -- comparisons, so the back end will never see an equality or inequality -- operation with operands of a record type. -- Note on overflow handling: When the overflow checking mode is set to -- MINIMIZED or ELIMINATED, nodes for signed arithmetic operations may -- be modified to use a larger type for the operands and result. In -- the case where the computed range exceeds that of Long_Long_Integer, -- and we are running in ELIMINATED mode, the operator node will be -- changed to be a call to the appropriate routine in System.Bignums. -- Note: In Modify_Tree_For_C mode, we do not generate an N_Op_Mod node -- for signed integer types (since there is no equivalent operator in -- C). Instead we rewrite such an operation in terms of REM (which is -- % in C) and other C-available operators. ------------------------------------ -- 4.5.7 Conditional Expressions -- ------------------------------------ -- CONDITIONAL_EXPRESSION ::= IF_EXPRESSION | CASE_EXPRESSION -------------------------- -- 4.5.7 If Expression -- -------------------------- -- IF_EXPRESSION ::= -- if CONDITION then DEPENDENT_EXPRESSION -- {elsif CONDITION then DEPENDENT_EXPRESSION} -- [else DEPENDENT_EXPRESSION] -- DEPENDENT_EXPRESSION ::= EXPRESSION -- Note: if we have (IF x1 THEN x2 ELSIF x3 THEN x4 ELSE x5) then it -- is represented as (IF x1 THEN x2 ELSE (IF x3 THEN x4 ELSE x5)) and -- the Is_Elsif flag is set on the inner if expression. -- N_If_Expression -- Sloc points to IF or ELSIF keyword -- Expressions -- Then_Actions -- Else_Actions -- Is_Elsif (set if comes from ELSIF) -- Do_Overflow_Check -- plus fields for expression -- Expressions here is a three-element list, whose first element is the -- condition, the second element is the dependent expression after THEN -- and the third element is the dependent expression after the ELSE -- (explicitly set to True if missing). -- Note: the Then_Actions and Else_Actions fields are always set to -- No_List in the tree passed to the back end. These are used only -- for temporary processing purposes in the expander. Even though they -- are semantic fields, their parent pointers are set because analysis -- of actions nodes in those lists may generate additional actions that -- need to know their insertion point (for example for the creation of -- transient scopes). -- Note: in the tree passed to the back end, if the result type is -- an unconstrained array, the if expression can only appears in the -- initializing expression of an object declaration (this avoids the -- back end having to create a variable length temporary on the fly). ---------------------------- -- 4.5.7 Case Expression -- ---------------------------- -- CASE_EXPRESSION ::= -- case SELECTING_EXPRESSION is -- CASE_EXPRESSION_ALTERNATIVE -- {,CASE_EXPRESSION_ALTERNATIVE} -- Note that the Alternatives cannot include pragmas (this contrasts -- with the situation of case statements where pragmas are allowed). -- N_Case_Expression -- Sloc points to CASE -- Expression (the selecting expression) -- Alternatives (the case expression alternatives) -- Etype -- Do_Overflow_Check ---------------------------------------- -- 4.5.7 Case Expression Alternative -- ---------------------------------------- -- CASE_EXPRESSION_ALTERNATIVE ::= -- when DISCRETE_CHOICE_LIST => -- DEPENDENT_EXPRESSION -- N_Case_Expression_Alternative -- Sloc points to WHEN -- Actions -- Discrete_Choices -- Expression -- Has_SP_Choice -- Note: The Actions field temporarily holds any actions associated with -- evaluation of the Expression. During expansion of the case expression -- these actions are wrapped into an N_Expression_With_Actions node -- replacing the original expression. -- Note: this node never appears in the tree passed to the back end, -- since the expander converts case expressions into case statements. --------------------------------- -- 4.5.8 Quantified Expression -- --------------------------------- -- QUANTIFIED_EXPRESSION ::= -- for QUANTIFIER LOOP_PARAMETER_SPECIFICATION => PREDICATE -- | for QUANTIFIER ITERATOR_SPECIFICATION => PREDICATE -- -- QUANTIFIER ::= all | some -- At most one of (Iterator_Specification, Loop_Parameter_Specification) -- is present at a time, in which case the other one is empty. -- N_Quantified_Expression -- Sloc points to FOR -- Iterator_Specification -- Loop_Parameter_Specification -- Condition -- All_Present -------------------------- -- 4.6 Type Conversion -- -------------------------- -- TYPE_CONVERSION ::= -- SUBTYPE_MARK (EXPRESSION) | SUBTYPE_MARK (NAME) -- In the (NAME) case, the name is stored as the expression -- Note: the parser never generates a type conversion node, since it -- looks like an indexed component which is generated by preference. -- The semantic pass must correct this misidentification. -- Gigi handles conversions that involve no change in the root type, -- and also all conversions from integer to floating-point types. -- Conversions from floating-point to integer are only handled in -- the case where Float_Truncate flag set. Other conversions from -- floating-point to integer (involving rounding) and all conversions -- involving fixed-point types are handled by the expander, unless the -- Conversion_OK flag is set. -- Sprint syntax if Float_Truncate set: X^(Y) -- Sprint syntax if Conversion_OK set X?(Y) -- Sprint syntax if both flags set X?^(Y) -- Note: If either the operand or result type is fixed-point, Gigi will -- only see a type conversion node with Conversion_OK set. The front end -- takes care of all handling of small's for fixed-point conversions. -- N_Type_Conversion -- Sloc points to first token of subtype mark -- Subtype_Mark -- Expression -- Do_Discriminant_Check -- Do_Length_Check -- Float_Truncate -- Conversion_OK -- Do_Overflow_Check -- Rounded_Result -- plus fields for expression -- Note: if a range check is required, then the Do_Range_Check flag -- is set in the Expression with the check being done against the -- target type range (after the base type conversion, if any). ------------------------------- -- 4.7 Qualified Expression -- ------------------------------- -- QUALIFIED_EXPRESSION ::= -- SUBTYPE_MARK ' (EXPRESSION) | SUBTYPE_MARK ' AGGREGATE -- Note: the parentheses in the (EXPRESSION) case are deemed to enclose -- the expression, so the Expression field of this node always points -- to a parenthesized expression in this case (i.e. Paren_Count will -- always be non-zero for the referenced expression if it is not an -- aggregate). -- N_Qualified_Expression -- Sloc points to apostrophe -- Subtype_Mark -- Expression expression or aggregate -- Is_Qualified_Universal_Literal -- plus fields for expression -------------------- -- 4.8 Allocator -- -------------------- -- ALLOCATOR ::= -- new [SUBPOOL_SPECIFICATION] SUBTYPE_INDICATION -- | new [SUBPOOL_SPECIFICATION] QUALIFIED_EXPRESSION -- -- SUBPOOL_SPECIFICATION ::= (subpool_handle_NAME) -- Sprint syntax (when storage pool present) -- new xxx (storage_pool = pool) -- or -- new (subpool) xxx (storage_pool = pool) -- N_Allocator -- Sloc points to NEW -- Expression subtype indication or qualified expression -- Subpool_Handle_Name (set to Empty if not present) -- Storage_Pool -- Procedure_To_Call -- For_Special_Return_Object -- Null_Exclusion_Present -- No_Initialization -- Is_Static_Coextension -- Do_Storage_Check -- Is_Dynamic_Coextension -- plus fields for expression -- Note: like all nodes, the N_Allocator has the Comes_From_Source flag. -- This flag has a special function in conjunction with the restriction -- No_Implicit_Heap_Allocations, which will be triggered if this flag -- is not set. This means that if a source allocator is replaced with -- a constructed allocator, the Comes_From_Source flag should be copied -- to the newly created allocator. --------------------------------- -- 5.1 Sequence Of Statements -- --------------------------------- -- SEQUENCE_OF_STATEMENTS ::= STATEMENT {STATEMENT} -- Note: Although the parser will not accept a declaration as a -- statement, the semantic analyzer may insert declarations (e.g. -- declarations of implicit types needed for execution of other -- statements) into a sequence of statements, so the code generator -- should be prepared to accept a declaration where a statement is -- expected. Note also that pragmas can appear as statements. -------------------- -- 5.1 Statement -- -------------------- -- STATEMENT ::= -- {LABEL} SIMPLE_STATEMENT | {LABEL} COMPOUND_STATEMENT -- There is no explicit node in the tree for a statement. Instead, the -- individual statement appears directly. Labels are treated as a -- kind of statement, i.e. they are linked into a statement list at -- the point they appear, so the labeled statement appears following -- the label or labels in the statement list. --------------------------- -- 5.1 Simple Statement -- --------------------------- -- SIMPLE_STATEMENT ::= NULL_STATEMENT -- | ASSIGNMENT_STATEMENT | EXIT_STATEMENT -- | GOTO_STATEMENT | PROCEDURE_CALL_STATEMENT -- | SIMPLE_RETURN_STATEMENT | ENTRY_CALL_STATEMENT -- | REQUEUE_STATEMENT | DELAY_STATEMENT -- | ABORT_STATEMENT | RAISE_STATEMENT -- | CODE_STATEMENT ----------------------------- -- 5.1 Compound Statement -- ----------------------------- -- COMPOUND_STATEMENT ::= -- IF_STATEMENT | CASE_STATEMENT -- | LOOP_STATEMENT | BLOCK_STATEMENT -- | EXTENDED_RETURN_STATEMENT -- | ACCEPT_STATEMENT | SELECT_STATEMENT ------------------------- -- 5.1 Null Statement -- ------------------------- -- NULL_STATEMENT ::= null; -- N_Null_Statement -- Sloc points to NULL -- Next_Rep_Item ---------------- -- 5.1 Label -- ---------------- -- LABEL ::= <> -- Note that the occurrence of a label is not a defining identifier, -- but rather a referencing occurrence. The defining occurrence is -- in the implicit label declaration which occurs in the innermost -- enclosing block. -- N_Label -- Sloc points to << -- Identifier direct name of statement identifier -- Exception_Junk -- Note: Before Ada 2012, a label is always followed by a statement, -- and this is true in the tree even in Ada 2012 mode (the parser -- inserts a null statement marked with Comes_From_Source False). ------------------------------- -- 5.1 Statement Identifier -- ------------------------------- -- STATEMENT_IDENTIFIER ::= DIRECT_NAME -- The IDENTIFIER of a STATEMENT_IDENTIFIER shall be an identifier -- (not an OPERATOR_SYMBOL) ------------------------------- -- 5.2 Assignment Statement -- ------------------------------- -- ASSIGNMENT_STATEMENT ::= -- variable_NAME := EXPRESSION; -- N_Assignment_Statement -- Sloc points to := -- Name -- Expression -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Do_Discriminant_Check -- Do_Length_Check -- Forwards_OK -- Backwards_OK -- No_Ctrl_Actions -- No_Finalize_Actions -- Has_Target_Names -- Is_Elaboration_Code -- Componentwise_Assignment -- Suppress_Assignment_Checks -- Note: if a range check is required, then the Do_Range_Check flag -- is set in the Expression (right hand side), with the check being -- done against the type of the Name (left hand side). -- Note: the back end places some restrictions on the form of the -- Expression field. If the object being assigned to is Atomic, then -- the Expression may not have the form of an aggregate (since this -- might cause the back end to generate separate assignments). In this -- case the front end must generate an extra temporary and initialize -- this temporary as required (the temporary itself is not atomic). ------------------ -- Target_Name -- ------------------ -- N_Target_Name -- Sloc points to @ -- Etype -- Note (Ada 2022): node is used during analysis as a placeholder for -- the value of the LHS of the enclosing assignment statement. Node is -- eventually rewritten together with enclosing assignment, and backends -- are not aware of it. ----------------------- -- 5.3 If Statement -- ----------------------- -- IF_STATEMENT ::= -- if CONDITION then -- SEQUENCE_OF_STATEMENTS -- {elsif CONDITION then -- SEQUENCE_OF_STATEMENTS} -- [else -- SEQUENCE_OF_STATEMENTS] -- end if; -- Gigi restriction: This expander ensures that the type of the -- Condition fields is always Standard.Boolean, even if the type -- in the source is some non-standard boolean type. -- N_If_Statement -- Sloc points to IF -- Condition -- Then_Statements -- Elsif_Parts (set to No_List if none present) -- Else_Statements (set to No_List if no else part present) -- End_Span (set to Uint_0 if expander generated) -- From_Conditional_Expression -- N_Elsif_Part -- Sloc points to ELSIF -- Condition -- Then_Statements -- Condition_Actions -------------------- -- 5.3 Condition -- -------------------- -- CONDITION ::= boolean_EXPRESSION ------------------------- -- 5.4 Case Statement -- ------------------------- -- CASE_STATEMENT ::= -- case EXPRESSION is -- CASE_STATEMENT_ALTERNATIVE -- {CASE_STATEMENT_ALTERNATIVE} -- end case; -- Note: the Alternatives can contain pragmas. These only occur at -- the start of the list, since any pragmas occurring after the first -- alternative are absorbed into the corresponding statement sequence. -- N_Case_Statement -- Sloc points to CASE -- Expression -- Alternatives -- End_Span (set to Uint_0 if expander generated) -- From_Conditional_Expression -- Note: Before Ada 2012, a pragma in a statement sequence is always -- followed by a statement, and this is true in the tree even in Ada -- 2012 mode (the parser inserts a null statement marked with the flag -- Comes_From_Source False). ------------------------------------- -- 5.4 Case Statement Alternative -- ------------------------------------- -- CASE_STATEMENT_ALTERNATIVE ::= -- when DISCRETE_CHOICE_LIST => -- SEQUENCE_OF_STATEMENTS -- N_Case_Statement_Alternative -- Sloc points to WHEN -- Discrete_Choices -- Statements -- Has_SP_Choice -- Multidefined_Bindings -- Note: in the list of Discrete_Choices, the tree passed to the back -- end does not have choice entries corresponding to names of statically -- predicated subtypes. Such entries are always expanded out to the list -- of equivalent values or ranges. Multidefined_Bindings is True iff -- more than one choice is present and each choice contains -- at least one component association having a non-null Binding_Chars -- attribute; this can only occur if GNAT extensions are enabled -- and the type of the case selector is composite. ------------------------- -- 5.5 Loop Statement -- ------------------------- -- LOOP_STATEMENT ::= -- [loop_STATEMENT_IDENTIFIER :] -- [ITERATION_SCHEME] loop -- SEQUENCE_OF_STATEMENTS -- end loop [loop_IDENTIFIER]; -- Note: The occurrence of a loop label is not a defining identifier -- but rather a referencing occurrence. The defining occurrence is in -- the implicit label declaration which occurs in the innermost -- enclosing block. -- Note: there is always a loop statement identifier present in the -- tree, even if none was given in the source. In the case where no loop -- identifier is given in the source, the parser creates a name of the -- form _Loop_n, where n is a decimal integer (the two underlines ensure -- that the loop names created in this manner do not conflict with any -- user defined identifiers), and the flag Has_Created_Identifier is set -- to True. The only exception to the rule that all loop statement nodes -- have identifiers occurs for loops constructed by the expander, and -- the semantic analyzer will create and supply dummy loop identifiers -- in these cases. -- N_Loop_Statement -- Sloc points to LOOP -- Identifier loop identifier (set to Empty if no identifier) -- Iteration_Scheme (set to Empty if no iteration scheme) -- Statements -- End_Label -- Has_Created_Identifier -- Is_Null_Loop -- Suppress_Loop_Warnings -- Note: the parser fills in the Identifier field if there is an -- explicit loop identifier. Otherwise the parser leaves this field -- set to Empty, and then the semantic processing for a loop statement -- creates an identifier, setting the Has_Created_Identifier flag to -- True. So after semantic analysis, the Identifier is always set, -- referencing an identifier whose entity has an Ekind of E_Loop. --------------------------- -- 5.5 Iteration Scheme -- --------------------------- -- ITERATION_SCHEME ::= -- while CONDITION -- | for LOOP_PARAMETER_SPECIFICATION -- | for ITERATOR_SPECIFICATION -- At most one of (Iterator_Specification, Loop_Parameter_Specification) -- is present at a time, in which case the other one is empty. Both are -- empty in the case of a WHILE loop. -- Gigi restriction: The expander ensures that the type of the Condition -- field is always Standard.Boolean, even if the type in the source is -- some non-standard boolean type. -- N_Iteration_Scheme -- Sloc points to WHILE or FOR -- Condition (set to Empty if FOR case) -- Condition_Actions -- Iterator_Specification (set to Empty if WHILE case) -- Loop_Parameter_Specification (set to Empty if WHILE case) --------------------------------------- -- 5.5 Loop Parameter Specification -- --------------------------------------- -- LOOP_PARAMETER_SPECIFICATION ::= -- DEFINING_IDENTIFIER in [reverse] DISCRETE_SUBTYPE_DEFINITION -- [Iterator_Filter] -- Note: the optional Iterator_Filter is an Ada 2022 construct. -- N_Loop_Parameter_Specification -- Sloc points to first identifier -- Defining_Identifier -- Reverse_Present -- Iterator_Filter (set to Empty if not present) -- Discrete_Subtype_Definition ----------------------------------- -- 5.5.1 Iterator Specification -- ----------------------------------- -- ITERATOR_SPECIFICATION ::= -- DEFINING_IDENTIFIER in [reverse] NAME -- | DEFINING_IDENTIFIER [: SUBTYPE_INDICATION] of [reverse] NAME -- N_Iterator_Specification -- Sloc points to defining identifier -- Defining_Identifier -- Name -- Reverse_Present -- Of_Present -- Iterator_Filter (set to Empty if not present) -- Subtype_Indication -- Note: The Of_Present flag distinguishes the two forms -------------------------- -- 5.6 Block Statement -- -------------------------- -- BLOCK_STATEMENT ::= -- [block_STATEMENT_IDENTIFIER:] -- [declare -- DECLARATIVE_PART] -- begin -- HANDLED_SEQUENCE_OF_STATEMENTS -- end [block_IDENTIFIER]; -- Note that the occurrence of a block identifier is not a defining -- identifier, but rather a referencing occurrence. The defining -- occurrence is an E_Block entity declared by the implicit label -- declaration which occurs in the innermost enclosing block statement -- or body; the block identifier denotes that E_Block. -- For block statements that come from source code, there is always a -- block statement identifier present in the tree, denoting an E_Block. -- In the case where no block identifier is given in the source, -- the parser creates a name of the form B_n, where n is a decimal -- integer, and the flag Has_Created_Identifier is set to True. Blocks -- constructed by the expander usually have no identifier, and no -- corresponding entity. -- Note: the block statement created for an extended return statement -- has an entity, and this entity is an E_Return_Statement, rather than -- the usual E_Block. -- Note: Exception_Junk is set for the wrapping blocks created during -- local raise optimization (Exp_Ch11.Expand_Local_Exception_Handlers). -- Note: from a control flow viewpoint, a block statement defines an -- extended basic block, i.e. the entry of the block dominates every -- statement in the sequence. When generating new statements with -- exception handlers in the expander at the end of a sequence that -- comes from source code, it can be necessary to wrap them all in a -- block statement in order to expose the implicit control flow to -- gigi and thus prevent it from issuing bogus control flow warnings. -- N_Block_Statement -- Sloc points to DECLARE or BEGIN -- Identifier block direct name (set to Empty if not present) -- Declarations (set to No_List if no DECLARE part) -- Handled_Statement_Sequence -- Activation_Chain_Entity -- Cleanup_Actions -- Has_Created_Identifier -- Is_Asynchronous_Call_Block -- Is_Task_Allocation_Block -- Exception_Junk -- Is_Abort_Block -- Is_Initialization_Block -- Is_Task_Master -- At_End_Proc (set to Empty if no clean up procedure) ------------------------- -- 5.7 Exit Statement -- ------------------------- -- EXIT_STATEMENT ::= exit [loop_NAME] [when CONDITION]; -- Gigi restriction: The expander ensures that the type of the Condition -- field is always Standard.Boolean, even if the type in the source is -- some non-standard boolean type. -- N_Exit_Statement -- Sloc points to EXIT -- Name (set to Empty if no loop name present) -- Condition (set to Empty if no WHEN part present) -- Next_Exit_Statement : Next exit on chain ------------------------- -- 5.9 Goto Statement -- ------------------------- -- GOTO_STATEMENT ::= goto label_NAME; -- N_Goto_Statement -- Sloc points to GOTO -- Name -- Exception_Junk --------------------------------- -- 6.1 Subprogram Declaration -- --------------------------------- -- SUBPROGRAM_DECLARATION ::= -- SUBPROGRAM_SPECIFICATION -- [ASPECT_SPECIFICATIONS]; -- N_Subprogram_Declaration -- Sloc points to FUNCTION or PROCEDURE -- Specification -- Body_To_Inline -- Corresponding_Body -- Parent_Spec -- Is_Entry_Barrier_Function -- Is_Task_Body_Procedure ------------------------------------------ -- 6.1 Abstract Subprogram Declaration -- ------------------------------------------ -- ABSTRACT_SUBPROGRAM_DECLARATION ::= -- SUBPROGRAM_SPECIFICATION is abstract -- [ASPECT_SPECIFICATIONS]; -- N_Abstract_Subprogram_Declaration -- Sloc points to ABSTRACT -- Specification ----------------------------------- -- 6.1 Subprogram Specification -- ----------------------------------- -- SUBPROGRAM_SPECIFICATION ::= -- [[not] overriding] -- procedure DEFINING_PROGRAM_UNIT_NAME PARAMETER_PROFILE -- | [[not] overriding] -- function DEFINING_DESIGNATOR PARAMETER_AND_RESULT_PROFILE -- Note: there are no separate nodes for the profiles, instead the -- information appears directly in the following nodes. -- N_Function_Specification -- Sloc points to FUNCTION -- Defining_Unit_Name (the designator) -- Parameter_Specifications (set to No_List if no formal part) -- Null_Exclusion_Present -- Result_Definition for result subtype -- Generic_Parent -- Must_Override set if overriding indicator present -- Must_Not_Override set if not_overriding indicator present -- N_Procedure_Specification -- Sloc points to PROCEDURE -- Defining_Unit_Name -- Null_Statement NULL statement for body, if Null_Present -- Parameter_Specifications (set to No_List if no formal part) -- Generic_Parent -- Null_Present set for null procedure case (Ada 2005 feature) -- Must_Override set if overriding indicator present -- Must_Not_Override set if not_overriding indicator present -- Note: overriding indicator is an Ada 2005 feature --------------------- -- 6.1 Designator -- --------------------- -- DESIGNATOR ::= -- [PARENT_UNIT_NAME .] IDENTIFIER | OPERATOR_SYMBOL -- Designators that are simply identifiers or operator symbols appear -- directly in the tree in this form. The following node is used only -- in the case where the designator has a parent unit name component. -- N_Designator -- Sloc points to period -- Name holds the parent unit name -- Identifier -- Note: Name is always non-Empty, since this node is only used for the -- case where a parent library unit package name is present. -- Note that the identifier can also be an operator symbol here ------------------------------ -- 6.1 Defining Designator -- ------------------------------ -- DEFINING_DESIGNATOR ::= -- DEFINING_PROGRAM_UNIT_NAME | DEFINING_OPERATOR_SYMBOL ------------------------------------- -- 6.1 Defining Program Unit Name -- ------------------------------------- -- DEFINING_PROGRAM_UNIT_NAME ::= -- [PARENT_UNIT_NAME .] DEFINING_IDENTIFIER -- The parent unit name is present only in the case of a child unit name -- (permissible only for Ada 95 for a library level unit, i.e. a unit -- at scope level one). If no such name is present, the defining program -- unit name is represented simply as the defining identifier. In the -- child unit case, the following node is used to represent the child -- unit name. -- N_Defining_Program_Unit_Name -- Sloc points to period -- Name holds the parent unit name -- Defining_Identifier -- Note: Name is always non-Empty, since this node is only used for the -- case where a parent unit name is present. -------------------------- -- 6.1 Operator Symbol -- -------------------------- -- OPERATOR_SYMBOL ::= STRING_LITERAL -- Note: the fields of the N_Operator_Symbol node are laid out to match -- the corresponding fields of an N_Character_Literal node. This allows -- easy conversion of the operator symbol node into a character literal -- node in the case where a string constant of the form of an operator -- symbol is scanned out as such, but turns out semantically to be a -- string literal that is not an operator. For details see Sinfo.CN. -- Change_Operator_Symbol_To_String_Literal. -- N_Operator_Symbol -- Sloc points to literal -- Chars contains the Name_Id for the operator symbol -- Strval Id of string value. This is used if the operator -- symbol turns out to be a normal string after all. -- Entity -- Associated_Node Note this is shared with Entity -- Etype -- Has_Private_View (set in generic units) -- Has_Secondary_Private_View (set in generic units) -- Note: the Strval field may be set to No_String for generated -- operator symbols that are known not to be string literals -- semantically. ----------------------------------- -- 6.1 Defining Operator Symbol -- ----------------------------------- -- DEFINING_OPERATOR_SYMBOL ::= OPERATOR_SYMBOL -- A defining operator symbol is an entity, which has additional -- fields depending on the setting of the Ekind field. These -- additional fields are defined (and access subprograms declared) -- in package Einfo. -- N_Defining_Operator_Symbol -- Sloc points to literal -- Chars contains the Name_Id for the operator symbol -- Next_Entity -- Scope -- Etype ---------------------------- -- 6.1 Parameter Profile -- ---------------------------- -- PARAMETER_PROFILE ::= [FORMAL_PART] --------------------------------------- -- 6.1 Parameter and Result Profile -- --------------------------------------- -- PARAMETER_AND_RESULT_PROFILE ::= -- [FORMAL_PART] return [NULL_EXCLUSION] SUBTYPE_MARK -- | [FORMAL_PART] return ACCESS_DEFINITION -- There is no explicit node in the tree for a parameter and result -- profile. Instead the information appears directly in the parent. ---------------------- -- 6.1 Formal Part -- ---------------------- -- FORMAL_PART ::= -- (PARAMETER_SPECIFICATION {; PARAMETER_SPECIFICATION}) ---------------------------------- -- 6.1 Parameter Specification -- ---------------------------------- -- PARAMETER_SPECIFICATION ::= -- DEFINING_IDENTIFIER_LIST : [ALIASED] MODE [NULL_EXCLUSION] -- SUBTYPE_MARK [:= DEFAULT_EXPRESSION] [ASPECT_SPECIFICATIONS] -- | DEFINING_IDENTIFIER_LIST : ACCESS_DEFINITION -- [:= DEFAULT_EXPRESSION] [ASPECT_SPECIFICATIONS] -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive specifications were given with -- identical type definition and expression components. To simplify -- semantic processing, the parser represents a multiple declaration -- case as a sequence of single Specifications, using the More_Ids and -- Prev_Ids flags to preserve the original source form as described -- in the section on "Handling of Defining Identifier Lists". -- ALIASED can only be present in Ada 2012 mode -- N_Parameter_Specification -- Sloc points to first identifier -- Defining_Identifier -- Aliased_Present -- In_Present -- Out_Present -- Null_Exclusion_Present -- Parameter_Type subtype mark or access definition -- Expression (set to Empty if no default expression present) -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) -- Default_Expression --------------- -- 6.1 Mode -- --------------- -- MODE ::= [in] | in out | out -- There is no explicit node in the tree for the Mode. Instead the -- In_Present and Out_Present flags are set in the parent node to -- record the presence of keywords specifying the mode. -------------------------- -- 6.3 Subprogram Body -- -------------------------- -- SUBPROGRAM_BODY ::= -- SUBPROGRAM_SPECIFICATION [ASPECT_SPECIFICATIONS] is -- DECLARATIVE_PART -- begin -- HANDLED_SEQUENCE_OF_STATEMENTS -- end [DESIGNATOR]; -- N_Subprogram_Body -- Sloc points to FUNCTION or PROCEDURE -- Specification -- Declarations -- Handled_Statement_Sequence -- Activation_Chain_Entity -- Corresponding_Spec -- Acts_As_Spec -- Bad_Is_Detected used only by parser -- Do_Storage_Check -- Has_Relative_Deadline_Pragma -- Is_Entry_Barrier_Function -- Is_Protected_Subprogram_Body -- Is_Task_Body_Procedure -- Is_Task_Master -- Was_Attribute_Reference -- Was_Expression_Function -- Was_Originally_Stub ----------------------------------- -- 6.4 Procedure Call Statement -- ----------------------------------- -- PROCEDURE_CALL_STATEMENT ::= -- procedure_NAME; | procedure_PREFIX ACTUAL_PARAMETER_PART; -- Note: the reason that a procedure call has expression fields is that -- it semantically resembles an expression, e.g. overloading is allowed -- and a type is concocted for semantic processing purposes. Certain of -- these fields, such as Parens are not relevant, but it is easier to -- just supply all of them together. -- N_Procedure_Call_Statement -- Sloc points to first token of name or prefix -- Name stores name or prefix -- Parameter_Associations (set to No_List if no -- actual parameter part) -- First_Named_Actual -- Controlling_Argument (set to Empty if not dispatching) -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- No_Elaboration_Check -- Is_Known_Guaranteed_ABE -- plus fields for expression -- If any IN parameter requires a range check, then the corresponding -- argument expression has the Do_Range_Check flag set, and the range -- check is done against the formal type. Note that this argument -- expression may appear directly in the Parameter_Associations list, -- or may be a descendant of an N_Parameter_Association node that -- appears in this list. ------------------------ -- 6.4 Function Call -- ------------------------ -- FUNCTION_CALL ::= -- function_NAME | function_PREFIX ACTUAL_PARAMETER_PART -- Note: the parser may generate an indexed component node or simply -- a name node instead of a function call node. The semantic pass must -- correct this misidentification. -- N_Function_Call -- Sloc points to first token of name or prefix -- Name stores name or prefix -- Parameter_Associations (set to No_List if no -- actual parameter part) -- First_Named_Actual -- Controlling_Argument (set to Empty if not dispatching) -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- No_Elaboration_Check -- Is_Expanded_Build_In_Place_Call -- Is_Known_Guaranteed_ABE -- plus fields for expression -------------------------------- -- 6.4 Actual Parameter Part -- -------------------------------- -- ACTUAL_PARAMETER_PART ::= -- (PARAMETER_ASSOCIATION {,PARAMETER_ASSOCIATION}) -------------------------------- -- 6.4 Parameter Association -- -------------------------------- -- PARAMETER_ASSOCIATION ::= -- [formal_parameter_SELECTOR_NAME =>] EXPLICIT_ACTUAL_PARAMETER -- Note: the N_Parameter_Association node is built only if a formal -- parameter selector name is present, otherwise the parameter -- association appears in the tree simply as the node for the -- explicit actual parameter. -- N_Parameter_Association -- Sloc points to formal parameter -- Selector_Name (always non-Empty) -- Explicit_Actual_Parameter -- Next_Named_Actual -- Is_Accessibility_Actual --------------------------- -- 6.4 Actual Parameter -- --------------------------- -- EXPLICIT_ACTUAL_PARAMETER ::= -- EXPRESSION | variable_NAME | REDUCTION_EXPRESSION_PARAMETER --------------------------- -- 6.5 Return Statement -- --------------------------- -- SIMPLE_RETURN_STATEMENT ::= return [EXPRESSION]; -- EXTENDED_RETURN_STATEMENT ::= -- return DEFINING_IDENTIFIER : [aliased] RETURN_SUBTYPE_INDICATION -- [:= EXPRESSION] [do -- HANDLED_SEQUENCE_OF_STATEMENTS -- end return]; -- RETURN_SUBTYPE_INDICATION ::= SUBTYPE_INDICATION | ACCESS_DEFINITION -- The term "return statement" is defined in 6.5 to mean either a -- SIMPLE_RETURN_STATEMENT or an EXTENDED_RETURN_STATEMENT. We avoid -- the use of this term, since it used to mean something else in earlier -- versions of Ada. -- N_Simple_Return_Statement -- Sloc points to RETURN -- Return_Statement_Entity -- Expression (set to Empty if no expression present) -- Storage_Pool -- Procedure_To_Call -- Comes_From_Extended_Return_Statement -- Note: Return_Statement_Entity points to an E_Return_Statement -- If a range check is required, then Do_Range_Check is set on the -- Expression. The check is against the return subtype of the function. -- N_Extended_Return_Statement -- Sloc points to RETURN -- Return_Statement_Entity -- Return_Object_Declarations -- Handled_Statement_Sequence (set to Empty if not present) -- Storage_Pool -- Procedure_To_Call -- Note: Return_Statement_Entity points to an E_Return_Statement. -- Note that Return_Object_Declarations is a list containing the -- N_Object_Declaration -- see comment on this field above. -- The declared object will have Is_Return_Object = True. -- There is no such syntactic category as return_object_declaration -- in the RM. Return_Object_Declarations represents this portion of -- the syntax for EXTENDED_RETURN_STATEMENT: -- DEFINING_IDENTIFIER : [aliased] RETURN_SUBTYPE_INDICATION -- [:= EXPRESSION] -- There are two entities associated with an extended_return_statement: -- the Return_Statement_Entity represents the statement itself, -- and the Defining_Identifier of the Object_Declaration in -- Return_Object_Declarations represents the object being -- returned. N_Simple_Return_Statement has only the former. ------------------------------ -- 6.8 Expression Function -- ------------------------------ -- EXPRESSION_FUNCTION ::= -- FUNCTION SPECIFICATION IS (EXPRESSION) -- [ASPECT_SPECIFICATIONS]; -- N_Expression_Function -- Sloc points to FUNCTION -- Specification -- Expression -- Corresponding_Spec ------------------------------ -- 7.1 Package Declaration -- ------------------------------ -- PACKAGE_DECLARATION ::= -- PACKAGE_SPECIFICATION; -- Note: the activation chain entity for a package spec is used for -- all tasks declared in the package spec, or in the package body. -- N_Package_Declaration -- Sloc points to PACKAGE -- Specification -- Corresponding_Body -- Parent_Spec -- Activation_Chain_Entity -------------------------------- -- 7.1 Package Specification -- -------------------------------- -- PACKAGE_SPECIFICATION ::= -- package DEFINING_PROGRAM_UNIT_NAME -- [ASPECT_SPECIFICATIONS] -- is -- {BASIC_DECLARATIVE_ITEM} -- [private -- {BASIC_DECLARATIVE_ITEM}] -- end [[PARENT_UNIT_NAME .] IDENTIFIER] -- N_Package_Specification -- Sloc points to PACKAGE -- Defining_Unit_Name -- Visible_Declarations -- Private_Declarations (set to No_List if no private -- part present) -- End_Label -- Generic_Parent -- Limited_View_Installed ----------------------- -- 7.1 Package Body -- ----------------------- -- PACKAGE_BODY ::= -- package body DEFINING_PROGRAM_UNIT_NAME -- [ASPECT_SPECIFICATIONS] -- is -- DECLARATIVE_PART -- [begin -- HANDLED_SEQUENCE_OF_STATEMENTS] -- end [[PARENT_UNIT_NAME .] IDENTIFIER]; -- N_Package_Body -- Sloc points to PACKAGE -- Defining_Unit_Name -- Declarations -- Handled_Statement_Sequence (set to Empty if no HSS present) -- Corresponding_Spec -- Was_Originally_Stub -- At_End_Proc (set to Empty if no clean up procedure) -- Note: if a source level package does not contain a handled sequence -- of statements, then the parser supplies a dummy one with a null -- sequence of statements. Comes_From_Source will be False in this -- constructed sequence. The reason we need this is for the End_Label -- field in the HSS. ----------------------------------- -- 7.4 Private Type Declaration -- ----------------------------------- -- PRIVATE_TYPE_DECLARATION ::= -- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] -- is [[abstract] tagged] [limited] private -- [ASPECT_SPECIFICATIONS]; -- Note: TAGGED is not permitted in Ada 83 mode -- N_Private_Type_Declaration -- Sloc points to TYPE -- Defining_Identifier -- Discriminant_Specifications (set to No_List if no -- discriminant part) -- Unknown_Discriminants_Present set if (<>) discriminant -- Abstract_Present -- Tagged_Present -- Limited_Present ---------------------------------------- -- 7.4 Private Extension Declaration -- ---------------------------------------- -- PRIVATE_EXTENSION_DECLARATION ::= -- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] is -- [abstract] [limited | synchronized] -- new ancestor_SUBTYPE_INDICATION [and INTERFACE_LIST] -- with private [ASPECT_SPECIFICATIONS]; -- Note: LIMITED, and private extension declarations are not allowed -- in Ada 83 mode. -- N_Private_Extension_Declaration -- Sloc points to TYPE -- Defining_Identifier -- Uninitialized_Variable -- Discriminant_Specifications (set to No_List if no -- discriminant part) -- Unknown_Discriminants_Present set if (<>) discriminant -- Abstract_Present -- Limited_Present -- Synchronized_Present -- Subtype_Indication -- Interface_List (set to No_List if none) --------------------- -- 8.4 Use Clause -- --------------------- -- USE_CLAUSE ::= USE_PACKAGE_CLAUSE | USE_TYPE_CLAUSE ----------------------------- -- 8.4 Use Package Clause -- ----------------------------- -- USE_PACKAGE_CLAUSE ::= use package_NAME {, package_NAME}; -- N_Use_Package_Clause -- Sloc points to USE -- Prev_Use_Clause -- Name -- Next_Use_Clause -- Associated_Node -- Hidden_By_Use_Clause -- Is_Effective_Use_Clause -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) -------------------------- -- 8.4 Use Type Clause -- -------------------------- -- USE_TYPE_CLAUSE ::= use [ALL] type SUBTYPE_MARK {, SUBTYPE_MARK}; -- Note: use type clause is not permitted in Ada 83 mode -- Note: the ALL keyword can appear only in Ada 2012 mode -- N_Use_Type_Clause -- Sloc points to USE -- Prev_Use_Clause -- Used_Operations -- Next_Use_Clause -- Subtype_Mark -- Hidden_By_Use_Clause -- Is_Effective_Use_Clause -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) -- All_Present ------------------------------- -- 8.5 Renaming Declaration -- ------------------------------- -- RENAMING_DECLARATION ::= -- OBJECT_RENAMING_DECLARATION -- | EXCEPTION_RENAMING_DECLARATION -- | PACKAGE_RENAMING_DECLARATION -- | SUBPROGRAM_RENAMING_DECLARATION -- | GENERIC_RENAMING_DECLARATION -------------------------------------- -- 8.5 Object Renaming Declaration -- -------------------------------------- -- OBJECT_RENAMING_DECLARATION ::= -- DEFINING_IDENTIFIER : -- [NULL_EXCLUSION] SUBTYPE_MARK renames object_NAME -- [ASPECT_SPECIFICATIONS]; -- | DEFINING_IDENTIFIER : -- ACCESS_DEFINITION renames object_NAME -- [ASPECT_SPECIFICATIONS]; -- Note: Access_Definition is an optional field that gives support to -- Ada 2005 (AI-230). The parser generates nodes that have either the -- Subtype_Indication field or else the Access_Definition field. -- N_Object_Renaming_Declaration -- Sloc points to first identifier -- Defining_Identifier -- Null_Exclusion_Present (set to False if not present) -- Subtype_Mark (set to Empty if not present) -- Access_Definition (set to Empty if not present) -- Name -- Corresponding_Generic_Association ----------------------------------------- -- 8.5 Exception Renaming Declaration -- ----------------------------------------- -- EXCEPTION_RENAMING_DECLARATION ::= -- DEFINING_IDENTIFIER : exception renames exception_NAME -- [ASPECT_SPECIFICATIONS]; -- N_Exception_Renaming_Declaration -- Sloc points to first identifier -- Defining_Identifier -- Name --------------------------------------- -- 8.5 Package Renaming Declaration -- --------------------------------------- -- PACKAGE_RENAMING_DECLARATION ::= -- package DEFINING_PROGRAM_UNIT_NAME renames package_NAME -- [ASPECT_SPECIFICATIONS]; -- N_Package_Renaming_Declaration -- Sloc points to PACKAGE -- Defining_Unit_Name -- Name -- Parent_Spec ------------------------------------------ -- 8.5 Subprogram Renaming Declaration -- ------------------------------------------ -- SUBPROGRAM_RENAMING_DECLARATION ::= -- SUBPROGRAM_SPECIFICATION renames callable_entity_NAME -- [ASPECT_SPECIFICATIONS]; -- N_Subprogram_Renaming_Declaration -- Sloc points to RENAMES -- Specification -- Name -- Parent_Spec -- Corresponding_Spec -- Corresponding_Formal_Spec -- From_Default ----------------------------------------- -- 8.5.5 Generic Renaming Declaration -- ----------------------------------------- -- GENERIC_RENAMING_DECLARATION ::= -- generic package DEFINING_PROGRAM_UNIT_NAME -- renames generic_package_NAME -- [ASPECT_SPECIFICATIONS]; -- | generic procedure DEFINING_PROGRAM_UNIT_NAME -- renames generic_procedure_NAME -- [ASPECT_SPECIFICATIONS]; -- | generic function DEFINING_PROGRAM_UNIT_NAME -- renames generic_function_NAME -- [ASPECT_SPECIFICATIONS]; -- N_Generic_Package_Renaming_Declaration -- Sloc points to GENERIC -- Defining_Unit_Name -- Name -- Parent_Spec -- N_Generic_Procedure_Renaming_Declaration -- Sloc points to GENERIC -- Defining_Unit_Name -- Name -- Parent_Spec -- N_Generic_Function_Renaming_Declaration -- Sloc points to GENERIC -- Defining_Unit_Name -- Name -- Parent_Spec -------------------------------- -- 9.1 Task Type Declaration -- -------------------------------- -- TASK_TYPE_DECLARATION ::= -- task type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART] -- [ASPECT_SPECIFICATIONS] -- [is [new INTERFACE_LIST with] TASK_DEFINITION]; -- N_Task_Type_Declaration -- Sloc points to TASK -- Defining_Identifier -- Discriminant_Specifications (set to No_List if no -- discriminant part) -- Interface_List (set to No_List if none) -- Task_Definition (set to Empty if not present) -- Corresponding_Body ---------------------------------- -- 9.1 Single Task Declaration -- ---------------------------------- -- SINGLE_TASK_DECLARATION ::= -- task DEFINING_IDENTIFIER -- [ASPECT_SPECIFICATIONS] -- [is [new INTERFACE_LIST with] TASK_DEFINITION]; -- N_Single_Task_Declaration -- Sloc points to TASK -- Defining_Identifier -- Interface_List (set to No_List if none) -- Task_Definition (set to Empty if not present) -------------------------- -- 9.1 Task Definition -- -------------------------- -- TASK_DEFINITION ::= -- {TASK_ITEM} -- [private -- {TASK_ITEM}] -- end [task_IDENTIFIER] -- Note: as a result of semantic analysis, the list of task items can -- include implicit type declarations resulting from entry families. -- N_Task_Definition -- Sloc points to first token of task definition -- Visible_Declarations -- Private_Declarations (set to No_List if no private part) -- End_Label -- Has_Storage_Size_Pragma -- Has_Relative_Deadline_Pragma -------------------- -- 9.1 Task Item -- -------------------- -- TASK_ITEM ::= ENTRY_DECLARATION | REPRESENTATION_CLAUSE -------------------- -- 9.1 Task Body -- -------------------- -- TASK_BODY ::= -- task body task_DEFINING_IDENTIFIER -- [ASPECT_SPECIFICATIONS] -- is -- DECLARATIVE_PART -- begin -- HANDLED_SEQUENCE_OF_STATEMENTS -- end [task_IDENTIFIER]; -- Gigi restriction: This node never appears -- N_Task_Body -- Sloc points to TASK -- Defining_Identifier -- Declarations -- Handled_Statement_Sequence -- Is_Task_Master -- Activation_Chain_Entity -- Corresponding_Spec -- Was_Originally_Stub ------------------------------------- -- 9.4 Protected Type Declaration -- ------------------------------------- -- PROTECTED_TYPE_DECLARATION ::= -- protected type DEFINING_IDENTIFIER [KNOWN_DISCRIMINANT_PART] -- [ASPECT_SPECIFICATIONS] -- is [new INTERFACE_LIST with] PROTECTED_DEFINITION; -- Note: protected type declarations are not permitted in Ada 83 mode -- N_Protected_Type_Declaration -- Sloc points to PROTECTED -- Defining_Identifier -- Discriminant_Specifications (set to No_List if no -- discriminant part) -- Interface_List (set to No_List if none) -- Protected_Definition -- Corresponding_Body --------------------------------------- -- 9.4 Single Protected Declaration -- --------------------------------------- -- SINGLE_PROTECTED_DECLARATION ::= -- protected DEFINING_IDENTIFIER -- [ASPECT_SPECIFICATIONS] -- is [new INTERFACE_LIST with] PROTECTED_DEFINITION; -- Note: single protected declarations are not allowed in Ada 83 mode -- N_Single_Protected_Declaration -- Sloc points to PROTECTED -- Defining_Identifier -- Interface_List (set to No_List if none) -- Protected_Definition ------------------------------- -- 9.4 Protected Definition -- ------------------------------- -- PROTECTED_DEFINITION ::= -- {PROTECTED_OPERATION_DECLARATION} -- [private -- {PROTECTED_ELEMENT_DECLARATION}] -- end [protected_IDENTIFIER] -- N_Protected_Definition -- Sloc points to first token of protected definition -- Visible_Declarations -- Private_Declarations (set to No_List if no private part) -- End_Label ------------------------------------------ -- 9.4 Protected Operation Declaration -- ------------------------------------------ -- PROTECTED_OPERATION_DECLARATION ::= -- SUBPROGRAM_DECLARATION -- | ENTRY_DECLARATION -- | REPRESENTATION_CLAUSE ---------------------------------------- -- 9.4 Protected Element Declaration -- ---------------------------------------- -- PROTECTED_ELEMENT_DECLARATION ::= -- PROTECTED_OPERATION_DECLARATION | COMPONENT_DECLARATION ------------------------- -- 9.4 Protected Body -- ------------------------- -- PROTECTED_BODY ::= -- protected body DEFINING_IDENTIFIER -- [ASPECT_SPECIFICATIONS]; -- is -- {PROTECTED_OPERATION_ITEM} -- end [protected_IDENTIFIER]; -- Note: protected bodies are not allowed in Ada 83 mode -- Gigi restriction: This node never appears -- N_Protected_Body -- Sloc points to PROTECTED -- Defining_Identifier -- Declarations protected operation items (and pragmas) -- End_Label -- Corresponding_Spec -- Was_Originally_Stub ----------------------------------- -- 9.4 Protected Operation Item -- ----------------------------------- -- PROTECTED_OPERATION_ITEM ::= -- SUBPROGRAM_DECLARATION -- | SUBPROGRAM_BODY -- | ENTRY_BODY -- | REPRESENTATION_CLAUSE ------------------------------ -- 9.5.2 Entry Declaration -- ------------------------------ -- ENTRY_DECLARATION ::= -- [[not] overriding] -- entry DEFINING_IDENTIFIER -- [(DISCRETE_SUBTYPE_DEFINITION)] PARAMETER_PROFILE -- [ASPECT_SPECIFICATIONS]; -- N_Entry_Declaration -- Sloc points to ENTRY -- Defining_Identifier -- Discrete_Subtype_Definition (set to Empty if not present) -- Parameter_Specifications (set to No_List if no formal part) -- Corresponding_Body -- Must_Override set if overriding indicator present -- Must_Not_Override set if not_overriding indicator present -- Note: overriding indicator is an Ada 2005 feature ----------------------------- -- 9.5.2 Accept statement -- ----------------------------- -- ACCEPT_STATEMENT ::= -- accept entry_DIRECT_NAME -- [(ENTRY_INDEX)] PARAMETER_PROFILE [do -- HANDLED_SEQUENCE_OF_STATEMENTS -- end [entry_IDENTIFIER]]; -- Gigi restriction: This node never appears -- Note: there are no explicit declarations allowed in an accept -- statement. However, the implicit declarations for any statement -- identifiers (labels and block/loop identifiers) are declarations -- that belong logically to the accept statement, and that is why -- there is a Declarations field in this node. -- N_Accept_Statement -- Sloc points to ACCEPT -- Entry_Direct_Name -- Entry_Index (set to Empty if not present) -- Parameter_Specifications (set to No_List if no formal part) -- Handled_Statement_Sequence -- Declarations (set to No_List if no declarations) ------------------------ -- 9.5.2 Entry Index -- ------------------------ -- ENTRY_INDEX ::= EXPRESSION ----------------------- -- 9.5.2 Entry Body -- ----------------------- -- ENTRY_BODY ::= -- entry DEFINING_IDENTIFIER ENTRY_BODY_FORMAL_PART ENTRY_BARRIER is -- DECLARATIVE_PART -- begin -- HANDLED_SEQUENCE_OF_STATEMENTS -- end [entry_IDENTIFIER]; -- ENTRY_BARRIER ::= when CONDITION -- Note: we store the CONDITION of the ENTRY_BARRIER in the node for -- the ENTRY_BODY_FORMAL_PART to avoid the N_Entry_Body node getting -- too full (it would otherwise have too many fields) -- Gigi restriction: This node never appears -- N_Entry_Body -- Sloc points to ENTRY -- Defining_Identifier -- Entry_Body_Formal_Part -- Declarations -- Handled_Statement_Sequence -- Activation_Chain_Entity -- Corresponding_Spec -- At_End_Proc (set to Empty if no clean up procedure) ----------------------------------- -- 9.5.2 Entry Body Formal Part -- ----------------------------------- -- ENTRY_BODY_FORMAL_PART ::= -- [(ENTRY_INDEX_SPECIFICATION)] PARAMETER_PROFILE -- Note that an entry body formal part node is present even if it is -- empty. This reflects the grammar, in which it is the components of -- the entry body formal part that are optional, not the entry body -- formal part itself. Also this means that the barrier condition -- always has somewhere to be stored. -- Gigi restriction: This node never appears -- N_Entry_Body_Formal_Part -- Sloc points to first token -- Entry_Index_Specification (set to Empty if not present) -- Parameter_Specifications (set to No_List if no formal part) -- Condition from entry barrier of entry body -------------------------- -- 9.5.2 Entry Barrier -- -------------------------- -- ENTRY_BARRIER ::= when CONDITION -------------------------------------- -- 9.5.2 Entry Index Specification -- -------------------------------------- -- ENTRY_INDEX_SPECIFICATION ::= -- for DEFINING_IDENTIFIER in DISCRETE_SUBTYPE_DEFINITION -- Gigi restriction: This node never appears -- N_Entry_Index_Specification -- Sloc points to FOR -- Defining_Identifier -- Discrete_Subtype_Definition --------------------------------- -- 9.5.3 Entry Call Statement -- --------------------------------- -- ENTRY_CALL_STATEMENT ::= entry_NAME [ACTUAL_PARAMETER_PART]; -- The parser may generate a procedure call for this construct. The -- semantic pass must correct this misidentification where needed. -- Gigi restriction: This node never appears -- N_Entry_Call_Statement -- Sloc points to first token of name -- Name -- Parameter_Associations (set to No_List if no -- actual parameter part) -- First_Named_Actual -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node ------------------------------ -- 9.5.4 Requeue Statement -- ------------------------------ -- REQUEUE_STATEMENT ::= requeue entry_NAME [with abort]; -- Note: requeue statements are not permitted in Ada 83 mode -- Gigi restriction: This node never appears -- N_Requeue_Statement -- Sloc points to REQUEUE -- Name -- Abort_Present -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -------------------------- -- 9.6 Delay Statement -- -------------------------- -- DELAY_STATEMENT ::= -- DELAY_UNTIL_STATEMENT -- | DELAY_RELATIVE_STATEMENT -------------------------------- -- 9.6 Delay Until Statement -- -------------------------------- -- DELAY_UNTIL_STATEMENT ::= delay until delay_EXPRESSION; -- Note: delay until statements are not permitted in Ada 83 mode -- Gigi restriction: This node never appears -- N_Delay_Until_Statement -- Sloc points to DELAY -- Expression ----------------------------------- -- 9.6 Delay Relative Statement -- ----------------------------------- -- DELAY_RELATIVE_STATEMENT ::= delay delay_EXPRESSION; -- Gigi restriction: This node never appears -- N_Delay_Relative_Statement -- Sloc points to DELAY -- Expression --------------------------- -- 9.7 Select Statement -- --------------------------- -- SELECT_STATEMENT ::= -- SELECTIVE_ACCEPT -- | TIMED_ENTRY_CALL -- | CONDITIONAL_ENTRY_CALL -- | ASYNCHRONOUS_SELECT ----------------------------- -- 9.7.1 Selective Accept -- ----------------------------- -- SELECTIVE_ACCEPT ::= -- select -- [GUARD] -- SELECT_ALTERNATIVE -- {or -- [GUARD] -- SELECT_ALTERNATIVE} -- [else -- SEQUENCE_OF_STATEMENTS] -- end select; -- Gigi restriction: This node never appears -- Note: the guard expression, if present, appears in the node for -- the select alternative. -- N_Selective_Accept -- Sloc points to SELECT -- Select_Alternatives -- Else_Statements (set to No_List if no else part) ------------------ -- 9.7.1 Guard -- ------------------ -- GUARD ::= when CONDITION => -- As noted above, the CONDITION that is part of a GUARD is included -- in the node for the select alternative for convenience. ------------------------------- -- 9.7.1 Select Alternative -- ------------------------------- -- SELECT_ALTERNATIVE ::= -- ACCEPT_ALTERNATIVE -- | DELAY_ALTERNATIVE -- | TERMINATE_ALTERNATIVE ------------------------------- -- 9.7.1 Accept Alternative -- ------------------------------- -- ACCEPT_ALTERNATIVE ::= -- ACCEPT_STATEMENT [SEQUENCE_OF_STATEMENTS] -- Gigi restriction: This node never appears -- N_Accept_Alternative -- Sloc points to ACCEPT -- Accept_Statement -- Condition from the guard (set to Empty if no guard present) -- Statements (set to Empty_List if no statements) -- Pragmas_Before pragmas before alt (set to No_List if none) -- Accept_Handler_Records ------------------------------ -- 9.7.1 Delay Alternative -- ------------------------------ -- DELAY_ALTERNATIVE ::= -- DELAY_STATEMENT [SEQUENCE_OF_STATEMENTS] -- Gigi restriction: This node never appears -- N_Delay_Alternative -- Sloc points to DELAY -- Delay_Statement -- Condition from the guard (set to Empty if no guard present) -- Statements (set to Empty_List if no statements) -- Pragmas_Before pragmas before alt (set to No_List if none) ---------------------------------- -- 9.7.1 Terminate Alternative -- ---------------------------------- -- TERMINATE_ALTERNATIVE ::= terminate; -- Gigi restriction: This node never appears -- N_Terminate_Alternative -- Sloc points to TERMINATE -- Condition from the guard (set to Empty if no guard present) -- Pragmas_Before pragmas before alt (set to No_List if none) -- Pragmas_After pragmas after alt (set to No_List if none) ----------------------------- -- 9.7.2 Timed Entry Call -- ----------------------------- -- TIMED_ENTRY_CALL ::= -- select -- ENTRY_CALL_ALTERNATIVE -- or -- DELAY_ALTERNATIVE -- end select; -- Gigi restriction: This node never appears -- N_Timed_Entry_Call -- Sloc points to SELECT -- Entry_Call_Alternative -- Delay_Alternative ----------------------------------- -- 9.7.2 Entry Call Alternative -- ----------------------------------- -- ENTRY_CALL_ALTERNATIVE ::= -- PROCEDURE_OR_ENTRY_CALL [SEQUENCE_OF_STATEMENTS] -- PROCEDURE_OR_ENTRY_CALL ::= -- PROCEDURE_CALL_STATEMENT | ENTRY_CALL_STATEMENT -- Gigi restriction: This node never appears -- N_Entry_Call_Alternative -- Sloc points to first token of entry call statement -- Entry_Call_Statement -- Statements (set to Empty_List if no statements) -- Pragmas_Before pragmas before alt (set to No_List if none) ----------------------------------- -- 9.7.3 Conditional Entry Call -- ----------------------------------- -- CONDITIONAL_ENTRY_CALL ::= -- select -- ENTRY_CALL_ALTERNATIVE -- else -- SEQUENCE_OF_STATEMENTS -- end select; -- Gigi restriction: This node never appears -- N_Conditional_Entry_Call -- Sloc points to SELECT -- Entry_Call_Alternative -- Else_Statements -------------------------------- -- 9.7.4 Asynchronous Select -- -------------------------------- -- ASYNCHRONOUS_SELECT ::= -- select -- TRIGGERING_ALTERNATIVE -- then abort -- ABORTABLE_PART -- end select; -- Note: asynchronous select is not permitted in Ada 83 mode -- Gigi restriction: This node never appears -- N_Asynchronous_Select -- Sloc points to SELECT -- Triggering_Alternative -- Abortable_Part ----------------------------------- -- 9.7.4 Triggering Alternative -- ----------------------------------- -- TRIGGERING_ALTERNATIVE ::= -- TRIGGERING_STATEMENT [SEQUENCE_OF_STATEMENTS] -- Gigi restriction: This node never appears -- N_Triggering_Alternative -- Sloc points to first token of triggering statement -- Triggering_Statement -- Statements (set to Empty_List if no statements) -- Pragmas_Before pragmas before alt (set to No_List if none) --------------------------------- -- 9.7.4 Triggering Statement -- --------------------------------- -- TRIGGERING_STATEMENT ::= PROCEDURE_OR_ENTRY_CALL | DELAY_STATEMENT --------------------------- -- 9.7.4 Abortable Part -- --------------------------- -- ABORTABLE_PART ::= SEQUENCE_OF_STATEMENTS -- Gigi restriction: This node never appears -- N_Abortable_Part -- Sloc points to ABORT -- Statements -------------------------- -- 9.8 Abort Statement -- -------------------------- -- ABORT_STATEMENT ::= abort task_NAME {, task_NAME}; -- Gigi restriction: This node never appears -- N_Abort_Statement -- Sloc points to ABORT -- Names ------------------------- -- 10.1.1 Compilation -- ------------------------- -- COMPILATION ::= {COMPILATION_UNIT} -- There is no explicit node in the tree for a compilation, since in -- general the compiler is processing only a single compilation unit -- at a time. It is possible to parse multiple units in syntax check -- only mode, but the trees are discarded in that case. ------------------------------ -- 10.1.1 Compilation Unit -- ------------------------------ -- COMPILATION_UNIT ::= -- CONTEXT_CLAUSE LIBRARY_ITEM -- | CONTEXT_CLAUSE SUBUNIT -- The N_Compilation_Unit node itself represents the above syntax. -- However, there are two additional items not reflected in the above -- syntax. First we have the global declarations that are added by the -- code generator. These are outer level declarations (so they cannot -- be represented as being inside the units). An example is the wrapper -- subprograms that are created to do ABE checking. As always a list of -- declarations can contain actions as well (i.e. statements), and such -- statements are executed as part of the elaboration of the unit. Note -- that all such declarations are elaborated before the library unit. -- Similarly, certain actions need to be elaborated at the completion -- of elaboration of the library unit (notably the statement that sets -- the Boolean flag indicating that elaboration is complete). -- The third item not reflected in the syntax is pragmas that appear -- after the compilation unit. As always pragmas are a problem since -- they are not part of the formal syntax, but can be stuck into the -- source following a set of ad hoc rules, and we have to find an ad -- hoc way of sticking them into the tree. For pragmas that appear -- before the library unit, we just consider them to be part of the -- context clause, and pragmas can appear in the Context_Items list -- of the compilation unit. However, pragmas can also appear after -- the library item. -- To deal with all these problems, we create an auxiliary node for -- a compilation unit, referenced from the N_Compilation_Unit node, -- that contains these items. -- N_Compilation_Unit -- Sloc points to first token of defining unit name -- Context_Items context items and pragmas preceding unit -- Private_Present set if library unit has private keyword -- Unit library item or subunit -- Aux_Decls_Node points to the N_Compilation_Unit_Aux node -- First_Inlined_Subprogram -- Library_Unit corresponding/parent spec/body -- Save_Invocation_Graph_Of_Body -- Acts_As_Spec flag for subprogram body with no spec -- Body_Required set for spec if body is required -- Has_Pragma_Suppress_All -- Context_Pending -- Has_No_Elaboration_Code -- N_Compilation_Unit_Aux -- Sloc is a copy of the Sloc from the N_Compilation_Unit node -- Declarations (set to No_List if no global declarations) -- Actions (set to No_List if no actions) -- Pragmas_After pragmas after unit (set to No_List if none) -- Config_Pragmas config pragmas (set to Empty_List if none) -- Default_Storage_Pool -------------------------- -- 10.1.1 Library Item -- -------------------------- -- LIBRARY_ITEM ::= -- [private] LIBRARY_UNIT_DECLARATION -- | LIBRARY_UNIT_BODY -- | [private] LIBRARY_UNIT_RENAMING_DECLARATION -- Note: PRIVATE is not allowed in Ada 83 mode -- There is no explicit node in the tree for library item, instead -- the declaration or body, and the flag for private if present, -- appear in the N_Compilation_Unit node. -------------------------------------- -- 10.1.1 Library Unit Declaration -- -------------------------------------- -- LIBRARY_UNIT_DECLARATION ::= -- SUBPROGRAM_DECLARATION | PACKAGE_DECLARATION -- | GENERIC_DECLARATION | GENERIC_INSTANTIATION ----------------------------------------------- -- 10.1.1 Library Unit Renaming Declaration -- ----------------------------------------------- -- LIBRARY_UNIT_RENAMING_DECLARATION ::= -- PACKAGE_RENAMING_DECLARATION -- | GENERIC_RENAMING_DECLARATION -- | SUBPROGRAM_RENAMING_DECLARATION ------------------------------- -- 10.1.1 Library unit body -- ------------------------------- -- LIBRARY_UNIT_BODY ::= SUBPROGRAM_BODY | PACKAGE_BODY ------------------------------ -- 10.1.1 Parent Unit Name -- ------------------------------ -- PARENT_UNIT_NAME ::= NAME ---------------------------- -- 10.1.2 Context clause -- ---------------------------- -- CONTEXT_CLAUSE ::= {CONTEXT_ITEM} -- The context clause can include pragmas, and any pragmas that appear -- before the context clause proper (i.e. all configuration pragmas, -- also appear at the front of this list). -------------------------- -- 10.1.2 Context_Item -- -------------------------- -- CONTEXT_ITEM ::= WITH_CLAUSE | USE_CLAUSE | WITH_TYPE_CLAUSE ------------------------- -- 10.1.2 With clause -- ------------------------- -- WITH_CLAUSE ::= -- with library_unit_NAME {,library_unit_NAME}; -- A separate With clause is built for each name, so that we have -- a Corresponding_Spec field for each with'ed spec. The flags -- First_Name and Last_Name are used to reconstruct the exact -- source form. When a list of names appears in one with clause, -- the first name in the list has First_Name set, and the last -- has Last_Name set. If the with clause has only one name, then -- both of the flags First_Name and Last_Name are set in this name. -- Note: in the case of implicit with's that are installed by the -- Rtsfind routine, Implicit_With is set, and the Sloc is typically -- set to Standard_Location, but it is incorrect to test the Sloc -- to find out if a with clause is implicit, test the flag instead. -- N_With_Clause -- Sloc points to first token of library unit name -- Name -- Private_Present set if with_clause has private keyword -- Limited_Present set if LIMITED is present -- Next_Implicit_With -- Library_Unit -- Corresponding_Spec -- First_Name (set to True if first name or only one name) -- Last_Name (set to True if last name or only one name) -- Context_Installed -- Elaborate_Present -- Elaborate_All_Present -- Elaborate_All_Desirable -- Elaborate_Desirable -- Implicit_With -- Limited_View_Installed -- Parent_With -- Unreferenced_In_Spec -- No_Entities_Ref_In_Spec -- Note: Limited_Present and Limited_View_Installed are used to support -- the implementation of Ada 2005 (AI-50217). -- Similarly, Private_Present is used to support the implementation of -- Ada 2005 (AI-50262). -- Note: if the WITH clause refers to a standard library unit, then a -- limited with clause is changed into a normal with clause, because we -- are not prepared to deal with limited with in the context of Rtsfind. -- So in this case, the Limited_Present flag will be False in the final -- tree. ---------------------- -- With_Type clause -- ---------------------- -- This is a GNAT extension, used to implement mutually recursive -- types declared in different packages. -- Note: this is now obsolete. The functionality of this construct -- is now implemented by the Ada 2005 limited_with_clause. --------------------- -- 10.2 Body stub -- --------------------- -- BODY_STUB ::= -- SUBPROGRAM_BODY_STUB -- | PACKAGE_BODY_STUB -- | TASK_BODY_STUB -- | PROTECTED_BODY_STUB ---------------------------------- -- 10.1.3 Subprogram Body Stub -- ---------------------------------- -- SUBPROGRAM_BODY_STUB ::= -- SUBPROGRAM_SPECIFICATION is separate -- [ASPECT_SPECIFICATION]; -- N_Subprogram_Body_Stub -- Sloc points to FUNCTION or PROCEDURE -- Specification -- Corresponding_Spec_Of_Stub -- Library_Unit points to the subunit -- Corresponding_Body -- At_End_Proc (set to Empty if no clean up procedure) ------------------------------- -- 10.1.3 Package Body Stub -- ------------------------------- -- PACKAGE_BODY_STUB ::= -- package body DEFINING_IDENTIFIER is separate -- [ASPECT_SPECIFICATION]; -- N_Package_Body_Stub -- Sloc points to PACKAGE -- Defining_Identifier -- Corresponding_Spec_Of_Stub -- Library_Unit points to the subunit -- Corresponding_Body ---------------------------- -- 10.1.3 Task Body Stub -- ---------------------------- -- TASK_BODY_STUB ::= -- task body DEFINING_IDENTIFIER is separate -- [ASPECT_SPECIFICATION]; -- N_Task_Body_Stub -- Sloc points to TASK -- Defining_Identifier -- Corresponding_Spec_Of_Stub -- Library_Unit points to the subunit -- Corresponding_Body -- At_End_Proc (set to Empty if no clean up procedure) --------------------------------- -- 10.1.3 Protected Body Stub -- --------------------------------- -- PROTECTED_BODY_STUB ::= -- protected body DEFINING_IDENTIFIER is separate -- [ASPECT_SPECIFICATION]; -- Note: protected body stubs are not allowed in Ada 83 mode -- N_Protected_Body_Stub -- Sloc points to PROTECTED -- Defining_Identifier -- Corresponding_Spec_Of_Stub -- Library_Unit points to the subunit -- Corresponding_Body --------------------- -- 10.1.3 Subunit -- --------------------- -- SUBUNIT ::= separate (PARENT_UNIT_NAME) PROPER_BODY -- N_Subunit -- Sloc points to SEPARATE -- Name is the name of the parent unit -- Proper_Body is the subunit body -- Corresponding_Stub is the stub declaration for the unit. --------------------------------- -- 11.1 Exception Declaration -- --------------------------------- -- EXCEPTION_DECLARATION ::= DEFINING_IDENTIFIER_LIST : exception -- [ASPECT_SPECIFICATIONS]; -- For consistency with object declarations etc., the parser converts -- the case of multiple identifiers being declared to a series of -- declarations in which the expression is copied, using the More_Ids -- and Prev_Ids flags to remember the source form as described in the -- section on "Handling of Defining Identifier Lists". -- N_Exception_Declaration -- Sloc points to EXCEPTION -- Defining_Identifier -- Expression -- Renaming_Exception -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) ------------------------------------------ -- 11.2 Handled Sequence Of Statements -- ------------------------------------------ -- HANDLED_SEQUENCE_OF_STATEMENTS ::= -- SEQUENCE_OF_STATEMENTS -- [exception -- EXCEPTION_HANDLER -- {EXCEPTION_HANDLER}] -- [at end -- cleanup_procedure_call (param, param, param, ...);] -- The AT END phrase is a GNAT extension to provide for cleanups. It is -- used only internally currently, but is considered to be syntactic. -- At the moment, the only cleanup action allowed is a single call to a -- parameterless procedure; this restriction could be lifted if we make -- some changes in gigi. The At_End_Proc field is an N_Identifier node -- that denotes the procedure to be called. The cleanup action occurs -- whenever the sequence of statements is left for any reason. The -- possible reasons are: -- -- 1. reaching the end of the sequence -- 2. exit, return, or goto -- 3. exception or abort -- -- The cleanup action also occurs whenever the exception handlers are -- left. -- The AT END cleanup handler protects only the sequence of statements -- and the exception handlers (not the associated declarations of -- the parent), just like exception handlers do not protect the -- declarations. The big difference is that the cleanup actions occur -- on either a normal or an abnormal exit from the statement sequence. -- At_End_Proc is also a field of various nodes that can contain -- both Declarations and Handled_Statement_Sequence, such as subprogram -- bodies and block statements. In that case, the At_End_Proc -- protects the Declarations as well as the Handled_Statement_Sequence. -- Note: the list of Exception_Handlers can contain pragmas as well -- as actual handlers. In practice these pragmas can only occur at -- the start of the list, since any pragmas occurring later on will -- be included in the statement list of the corresponding handler. -- Note: although in the Ada syntax, the sequence of statements in -- a handled sequence of statements can only contain statements, we -- allow free mixing of declarations and statements in the resulting -- expanded tree. This is for example used to deal with the case of -- a cleanup procedure that must handle declarations as well as the -- statements of a block. -- Note: the cleanup_procedure_call does not go through the common -- processing for calls, which in particular means that it will not be -- automatically inlined in all cases, even though the procedure to be -- called is marked inline. More specifically, if the procedure comes -- from another unit than the main source unit, for example a run-time -- unit, then it needs to be manually added to the list of bodies to be -- inlined by invoking Add_Inlined_Body on it. -- N_Handled_Sequence_Of_Statements -- Sloc points to first token of first statement -- Statements -- End_Label (set to Empty if expander generated) -- Exception_Handlers (set to No_List if none present) -- At_End_Proc (set to Empty if no clean up procedure) -- Note: A Handled_Sequence_Of_Statements can contain both -- Exception_Handlers and an At_End_Proc. -- Note: the parent always contains a Declarations field which contains -- declarations associated with the handled sequence of statements. This -- is true even in the case of an accept statement (see description of -- the N_Accept_Statement node). -- End_Label refers to the containing construct ----------------------------- -- 11.2 Exception Handler -- ----------------------------- -- EXCEPTION_HANDLER ::= -- when [CHOICE_PARAMETER_SPECIFICATION :] -- EXCEPTION_CHOICE {| EXCEPTION_CHOICE} => -- SEQUENCE_OF_STATEMENTS -- Note: choice parameter specification is not allowed in Ada 83 mode -- N_Exception_Handler -- Sloc points to WHEN -- Choice_Parameter (set to Empty if not present) -- Exception_Choices -- Statements -- Exception_Label (set to Empty if not present) -- Local_Raise_Statements (set to No_Elist if not present) -- Local_Raise_Not_OK -- Has_Local_Raise ------------------------------------------ -- 11.2 Choice parameter specification -- ------------------------------------------ -- CHOICE_PARAMETER_SPECIFICATION ::= DEFINING_IDENTIFIER ---------------------------- -- 11.2 Exception Choice -- ---------------------------- -- EXCEPTION_CHOICE ::= exception_NAME | others -- Except in the case of OTHERS, no explicit node appears in the tree -- for exception choice. Instead the exception name appears directly. -- An OTHERS choice is represented by a N_Others_Choice node (see -- section 3.8.1. -- Note: for the exception choice created for an at end handler, the -- exception choice is an N_Others_Choice node with All_Others set. --------------------------- -- 11.3 Raise Statement -- --------------------------- -- RAISE_STATEMENT ::= raise [exception_NAME]; -- In Ada 2005, we have -- RAISE_STATEMENT ::= -- raise; | raise exception_NAME [with string_EXPRESSION]; -- N_Raise_Statement -- Sloc points to RAISE -- Name (set to Empty if no exception name present) -- Expression (set to Empty if no expression present) ---------------------------- -- 11.3 Raise Expression -- ---------------------------- -- RAISE_EXPRESSION ::= raise exception_NAME [with string_EXPRESSION] -- N_Raise_Expression -- Sloc points to RAISE -- Name (always present) -- Expression (set to Empty if no expression present) -- plus fields for expression ------------------------------- -- 12.1 Generic Declaration -- ------------------------------- -- GENERIC_DECLARATION ::= -- GENERIC_SUBPROGRAM_DECLARATION | GENERIC_PACKAGE_DECLARATION ------------------------------------------ -- 12.1 Generic Subprogram Declaration -- ------------------------------------------ -- GENERIC_SUBPROGRAM_DECLARATION ::= -- GENERIC_FORMAL_PART SUBPROGRAM_SPECIFICATION -- [ASPECT_SPECIFICATIONS]; -- Note: Generic_Formal_Declarations can include pragmas -- N_Generic_Subprogram_Declaration -- Sloc points to GENERIC -- Specification subprogram specification -- Corresponding_Body -- Generic_Formal_Declarations from generic formal part -- Parent_Spec --------------------------------------- -- 12.1 Generic Package Declaration -- --------------------------------------- -- GENERIC_PACKAGE_DECLARATION ::= -- GENERIC_FORMAL_PART PACKAGE_SPECIFICATION -- [ASPECT_SPECIFICATIONS]; -- Note: when we do generics right, the Activation_Chain_Entity entry -- for this node can be removed (since the expander won't see generic -- units any more)???. -- Note: Generic_Formal_Declarations can include pragmas -- N_Generic_Package_Declaration -- Sloc points to GENERIC -- Specification package specification -- Corresponding_Body -- Generic_Formal_Declarations from generic formal part -- Parent_Spec -- Activation_Chain_Entity ------------------------------- -- 12.1 Generic Formal Part -- ------------------------------- -- GENERIC_FORMAL_PART ::= -- generic {GENERIC_FORMAL_PARAMETER_DECLARATION | USE_CLAUSE} ------------------------------------------------ -- 12.1 Generic Formal Parameter Declaration -- ------------------------------------------------ -- GENERIC_FORMAL_PARAMETER_DECLARATION ::= -- FORMAL_OBJECT_DECLARATION -- | FORMAL_TYPE_DECLARATION -- | FORMAL_SUBPROGRAM_DECLARATION -- | FORMAL_PACKAGE_DECLARATION --------------------------------- -- 12.3 Generic Instantiation -- --------------------------------- -- GENERIC_INSTANTIATION ::= -- package DEFINING_PROGRAM_UNIT_NAME is -- new generic_package_NAME [GENERIC_ACTUAL_PART] -- [ASPECT_SPECIFICATIONS]; -- | [[not] overriding] -- procedure DEFINING_PROGRAM_UNIT_NAME is -- new generic_procedure_NAME [GENERIC_ACTUAL_PART] -- [ASPECT_SPECIFICATIONS]; -- | [[not] overriding] -- function DEFINING_DESIGNATOR is -- new generic_function_NAME [GENERIC_ACTUAL_PART] -- [ASPECT_SPECIFICATIONS]; -- N_Package_Instantiation -- Sloc points to PACKAGE -- Defining_Unit_Name -- Name -- Generic_Associations (set to No_List if no -- generic actual part) -- Parent_Spec -- Instance_Spec -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Is_Declaration_Level_Node -- Is_Known_Guaranteed_ABE -- N_Procedure_Instantiation -- Sloc points to PROCEDURE -- Defining_Unit_Name -- Name -- Parent_Spec -- Generic_Associations (set to No_List if no -- generic actual part) -- Instance_Spec -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Is_Declaration_Level_Node -- Must_Override set if overriding indicator present -- Must_Not_Override set if not_overriding indicator present -- Is_Known_Guaranteed_ABE -- N_Function_Instantiation -- Sloc points to FUNCTION -- Defining_Unit_Name -- Name -- Generic_Associations (set to No_List if no -- generic actual part) -- Parent_Spec -- Instance_Spec -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Is_Declaration_Level_Node -- Must_Override set if overriding indicator present -- Must_Not_Override set if not_overriding indicator present -- Is_Known_Guaranteed_ABE -- Note: overriding indicator is an Ada 2005 feature ------------------------------- -- 12.3 Generic Actual Part -- ------------------------------- -- GENERIC_ACTUAL_PART ::= -- (GENERIC_ASSOCIATION {, GENERIC_ASSOCIATION}) ------------------------------- -- 12.3 Generic Association -- ------------------------------- -- GENERIC_ASSOCIATION ::= -- [generic_formal_parameter_SELECTOR_NAME =>] -- Note: unlike the procedure call case, a generic association node -- is generated for every association, even if no formal parameter -- selector name is present. In this case the parser will leave the -- Selector_Name field set to Empty, to be filled in later by the -- semantic pass. -- In Ada 2005, a formal may be associated with a box, if the -- association is part of the list of actuals for a formal package. -- If the association is given by OTHERS => <>, the association is -- an N_Others_Choice. -- N_Generic_Association -- Sloc points to first token of generic association -- Selector_Name (set to Empty if no formal -- parameter selector name) -- Explicit_Generic_Actual_Parameter (Empty if box present) -- Box_Present (for formal_package associations with a box) --------------------------------------------- -- 12.3 Explicit Generic Actual Parameter -- --------------------------------------------- -- EXPLICIT_GENERIC_ACTUAL_PARAMETER ::= -- EXPRESSION | variable_NAME | subprogram_NAME -- | entry_NAME | SUBTYPE_MARK | package_instance_NAME ------------------------------------- -- 12.4 Formal Object Declaration -- ------------------------------------- -- FORMAL_OBJECT_DECLARATION ::= -- DEFINING_IDENTIFIER_LIST : -- MODE [NULL_EXCLUSION] SUBTYPE_MARK [:= DEFAULT_EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- | DEFINING_IDENTIFIER_LIST : -- MODE ACCESS_DEFINITION [:= DEFAULT_EXPRESSION] -- [ASPECT_SPECIFICATIONS]; -- Although the syntax allows multiple identifiers in the list, the -- semantics is as though successive declarations were given with -- identical type definition and expression components. To simplify -- semantic processing, the parser represents a multiple declaration -- case as a sequence of single declarations, using the More_Ids and -- Prev_Ids flags to preserve the original source form as described -- in the section on "Handling of Defining Identifier Lists". -- N_Formal_Object_Declaration -- Sloc points to first identifier -- Defining_Identifier -- In_Present -- Out_Present -- Null_Exclusion_Present (set to False if not present) -- Subtype_Mark (set to Empty if not present) -- Access_Definition (set to Empty if not present) -- Default_Expression (set to Empty if no default expression) -- More_Ids (set to False if no more identifiers in list) -- Prev_Ids (set to False if no previous identifiers in list) ----------------------------------- -- 12.5 Formal Type Declaration -- ----------------------------------- -- FORMAL_TYPE_DECLARATION ::= -- type DEFINING_IDENTIFIER [DISCRIMINANT_PART] -- is FORMAL_TYPE_DEFINITION -- [ASPECT_SPECIFICATIONS]; -- | type DEFINING_IDENTIFIER [DISCRIMINANT_PART] [is tagged] -- N_Formal_Type_Declaration -- Sloc points to TYPE -- Defining_Identifier -- Formal_Type_Definition -- Discriminant_Specifications (set to No_List if no -- discriminant part) -- Unknown_Discriminants_Present set if (<>) discriminant -- Default_Subtype_Mark ---------------------------------- -- 12.5 Formal type definition -- ---------------------------------- -- FORMAL_TYPE_DEFINITION ::= -- FORMAL_PRIVATE_TYPE_DEFINITION -- | FORMAL_DERIVED_TYPE_DEFINITION -- | FORMAL_DISCRETE_TYPE_DEFINITION -- | FORMAL_SIGNED_INTEGER_TYPE_DEFINITION -- | FORMAL_MODULAR_TYPE_DEFINITION -- | FORMAL_FLOATING_POINT_DEFINITION -- | FORMAL_ORDINARY_FIXED_POINT_DEFINITION -- | FORMAL_DECIMAL_FIXED_POINT_DEFINITION -- | FORMAL_ARRAY_TYPE_DEFINITION -- | FORMAL_ACCESS_TYPE_DEFINITION -- | FORMAL_INTERFACE_TYPE_DEFINITION -- | FORMAL_INCOMPLETE_TYPE_DEFINITION -- The Ada 2012 syntax introduces two new non-terminals: -- Formal_{Complete,Incomplete}_Type_Declaration just to introduce -- the latter category. Here we introduce an incomplete type definition -- in order to preserve as much as possible the existing structure. --------------------------------------------- -- 12.5.1 Formal Private Type Definition -- --------------------------------------------- -- FORMAL_PRIVATE_TYPE_DEFINITION ::= -- [[abstract] tagged] [limited] private -- Note: TAGGED is not allowed in Ada 83 mode -- N_Formal_Private_Type_Definition -- Sloc points to PRIVATE -- Uninitialized_Variable -- Abstract_Present -- Tagged_Present -- Limited_Present -------------------------------------------- -- 12.5.1 Formal Derived Type Definition -- -------------------------------------------- -- FORMAL_DERIVED_TYPE_DEFINITION ::= -- [abstract] [limited | synchronized] -- new SUBTYPE_MARK [[and INTERFACE_LIST] with private] -- Note: this construct is not allowed in Ada 83 mode -- N_Formal_Derived_Type_Definition -- Sloc points to NEW -- Subtype_Mark -- Private_Present -- Abstract_Present -- Limited_Present -- Synchronized_Present -- Interface_List (set to No_List if none) ----------------------------------------------- -- 12.5.1 Formal Incomplete Type Definition -- ----------------------------------------------- -- FORMAL_INCOMPLETE_TYPE_DEFINITION ::= [tagged] -- N_Formal_Incomplete_Type_Definition -- Sloc points to identifier of parent -- Tagged_Present --------------------------------------------- -- 12.5.2 Formal Discrete Type Definition -- --------------------------------------------- -- FORMAL_DISCRETE_TYPE_DEFINITION ::= (<>) -- N_Formal_Discrete_Type_Definition -- Sloc points to ( --------------------------------------------------- -- 12.5.2 Formal Signed Integer Type Definition -- --------------------------------------------------- -- FORMAL_SIGNED_INTEGER_TYPE_DEFINITION ::= range <> -- N_Formal_Signed_Integer_Type_Definition -- Sloc points to RANGE -------------------------------------------- -- 12.5.2 Formal Modular Type Definition -- -------------------------------------------- -- FORMAL_MODULAR_TYPE_DEFINITION ::= mod <> -- N_Formal_Modular_Type_Definition -- Sloc points to MOD ---------------------------------------------- -- 12.5.2 Formal Floating Point Definition -- ---------------------------------------------- -- FORMAL_FLOATING_POINT_DEFINITION ::= digits <> -- N_Formal_Floating_Point_Definition -- Sloc points to DIGITS ---------------------------------------------------- -- 12.5.2 Formal Ordinary Fixed Point Definition -- ---------------------------------------------------- -- FORMAL_ORDINARY_FIXED_POINT_DEFINITION ::= delta <> -- N_Formal_Ordinary_Fixed_Point_Definition -- Sloc points to DELTA --------------------------------------------------- -- 12.5.2 Formal Decimal Fixed Point Definition -- --------------------------------------------------- -- FORMAL_DECIMAL_FIXED_POINT_DEFINITION ::= delta <> digits <> -- Note: formal decimal fixed point definition not allowed in Ada 83 -- N_Formal_Decimal_Fixed_Point_Definition -- Sloc points to DELTA ------------------------------------------ -- 12.5.3 Formal Array Type Definition -- ------------------------------------------ -- FORMAL_ARRAY_TYPE_DEFINITION ::= ARRAY_TYPE_DEFINITION ------------------------------------------- -- 12.5.4 Formal Access Type Definition -- ------------------------------------------- -- FORMAL_ACCESS_TYPE_DEFINITION ::= ACCESS_TYPE_DEFINITION ---------------------------------------------- -- 12.5.5 Formal Interface Type Definition -- ---------------------------------------------- -- FORMAL_INTERFACE_TYPE_DEFINITION ::= INTERFACE_TYPE_DEFINITION ----------------------------------------- -- 12.6 Formal Subprogram Declaration -- ----------------------------------------- -- FORMAL_SUBPROGRAM_DECLARATION ::= -- FORMAL_CONCRETE_SUBPROGRAM_DECLARATION -- | FORMAL_ABSTRACT_SUBPROGRAM_DECLARATION -------------------------------------------------- -- 12.6 Formal Concrete Subprogram Declaration -- -------------------------------------------------- -- FORMAL_CONCRETE_SUBPROGRAM_DECLARATION ::= -- with SUBPROGRAM_SPECIFICATION [is SUBPROGRAM_DEFAULT] -- [ASPECT_SPECIFICATIONS]; -- N_Formal_Concrete_Subprogram_Declaration -- Sloc points to WITH -- Specification -- Default_Name (set to Empty if no subprogram default) -- Box_Present -- Expression (set to Empty if no expression present) -- Note: If no subprogram default is present, then Name is set -- to Empty, and Box_Present is False. -- Note: The Expression field is only used for the GNAT extension -- that allows a FORMAL_CONCRETE_SUBPROGRAM_DECLARATION to specify -- an expression default for generic formal functions. -------------------------------------------------- -- 12.6 Formal Abstract Subprogram Declaration -- -------------------------------------------------- -- FORMAL_ABSTRACT_SUBPROGRAM_DECLARATION ::= -- with SUBPROGRAM_SPECIFICATION is abstract [SUBPROGRAM_DEFAULT] -- [ASPECT_SPECIFICATIONS]; -- N_Formal_Abstract_Subprogram_Declaration -- Sloc points to WITH -- Specification -- Default_Name (set to Empty if no subprogram default) -- Box_Present -- Note: if no subprogram default is present, then Name is set -- to Empty, and Box_Present is False. ------------------------------ -- 12.6 Subprogram Default -- ------------------------------ -- SUBPROGRAM_DEFAULT ::= DEFAULT_NAME | <> | (EXPRESSION) -- There is no separate node in the tree for a subprogram default. -- Instead the parent (N_Formal_Concrete_Subprogram_Declaration -- or N_Formal_Abstract_Subprogram_Declaration) node contains the -- default name or box indication, as needed. -- Note: The syntax "(EXPRESSION)" is a GNAT extension, and allows -- a FORMAL_CONCRETE_SUBPROGRAM_DECLARATION to specify an expression -- default for formal functions, in analogy with expression_functions. ------------------------ -- 12.6 Default Name -- ------------------------ -- DEFAULT_NAME ::= NAME -------------------------------------- -- 12.7 Formal Package Declaration -- -------------------------------------- -- FORMAL_PACKAGE_DECLARATION ::= -- with package DEFINING_IDENTIFIER -- is new generic_package_NAME FORMAL_PACKAGE_ACTUAL_PART -- [ASPECT_SPECIFICATIONS]; -- Note: formal package declarations not allowed in Ada 83 mode -- N_Formal_Package_Declaration -- Sloc points to WITH -- Defining_Identifier -- Name -- Generic_Associations (set to No_List if (<>) case or -- empty generic actual part) -- Box_Present -- Instance_Spec -- Is_Known_Guaranteed_ABE -------------------------------------- -- 12.7 Formal Package Actual Part -- -------------------------------------- -- FORMAL_PACKAGE_ACTUAL_PART ::= -- ([OTHERS] => <>) -- | [GENERIC_ACTUAL_PART] -- (FORMAL_PACKAGE_ASSOCIATION {. FORMAL_PACKAGE_ASSOCIATION} -- FORMAL_PACKAGE_ASSOCIATION ::= -- GENERIC_ASSOCIATION -- | GENERIC_FORMAL_PARAMETER_SELECTOR_NAME => <> -- There is no explicit node in the tree for a formal package actual -- part. Instead the information appears in the parent node (i.e. the -- formal package declaration node itself). -- There is no explicit node for a formal package association. All of -- them are represented either by a generic association, possibly with -- Box_Present, or by an N_Others_Choice. --------------------------------- -- 13.1 Representation clause -- --------------------------------- -- REPRESENTATION_CLAUSE ::= -- ATTRIBUTE_DEFINITION_CLAUSE -- | ENUMERATION_REPRESENTATION_CLAUSE -- | RECORD_REPRESENTATION_CLAUSE -- | AT_CLAUSE ---------------------- -- 13.1 Local Name -- ---------------------- -- LOCAL_NAME := -- DIRECT_NAME -- | DIRECT_NAME'ATTRIBUTE_DESIGNATOR -- | library_unit_NAME -- The construct DIRECT_NAME'ATTRIBUTE_DESIGNATOR appears in the tree -- as an attribute reference, which has essentially the same form. --------------------------------------- -- 13.3 Attribute definition clause -- --------------------------------------- -- ATTRIBUTE_DEFINITION_CLAUSE ::= -- for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use EXPRESSION; -- | for LOCAL_NAME'ATTRIBUTE_DESIGNATOR use NAME; -- In Ada 83, the expression must be a simple expression and the -- local name must be a direct name. -- Note: the only attribute definition clause that is processed by -- gigi is an address clause. For all other cases, the information -- is extracted by the front end and either results in setting entity -- information, e.g. Esize for the Size clause, or in appropriate -- expansion actions (e.g. in the case of Storage_Size). -- For an address clause, Gigi constructs the appropriate addressing -- code. It also ensures that no aliasing optimizations are made -- for the object for which the address clause appears. -- Note: for an address clause used to achieve an overlay: -- A : Integer; -- B : Integer; -- for B'Address use A'Address; -- the above rule means that Gigi will ensure that no optimizations -- will be made for B that would violate the implementation advice -- of RM 13.3(19). However, this advice applies only to B and not -- to A, which seems unfortunate. The GNAT front end will mark the -- object A as volatile to also prevent unwanted optimization -- assumptions based on no aliasing being made for B. -- N_Attribute_Definition_Clause -- Sloc points to FOR -- Name the local name -- Chars the identifier name from the attribute designator -- Expression the expression or name -- Entity -- Next_Rep_Item -- From_At_Mod -- Check_Address_Alignment -- From_Aspect_Specification -- Is_Delayed_Aspect -- Address_Warning_Posted -- Note: if From_Aspect_Specification is set, then Sloc points to the -- aspect name, and Entity is resolved already to reference the entity -- to which the aspect applies. ----------------------------------- -- 13.3.1 Aspect Specifications -- ----------------------------------- -- We modify the RM grammar here, the RM grammar is: -- ASPECT_SPECIFICATION ::= -- with ASPECT_MARK [=> ASPECT_DEFINITION] {, -- ASPECT_MARK [=> ASPECT_DEFINITION] } -- ASPECT_MARK ::= aspect_IDENTIFIER['Class] -- ASPECT_DEFINITION ::= NAME | EXPRESSION -- That's inconvenient, since there is no non-terminal name for a single -- entry in the list of aspects. So we use this grammar instead: -- ASPECT_SPECIFICATIONS ::= -- with ASPECT_SPECIFICATION {, ASPECT_SPECIFICATION} -- ASPECT_SPECIFICATION => -- ASPECT_MARK [=> ASPECT_DEFINITION] -- ASPECT_MARK ::= aspect_IDENTIFIER['Class] -- ASPECT_DEFINITION ::= NAME | EXPRESSION -- Note that for Annotate, the ASPECT_DEFINITION is a pure positional -- aggregate with the elements of the aggregate corresponding to the -- successive arguments of the corresponding pragma. -- See separate package Aspects for details on the incorporation of -- these nodes into the tree, and how aspect specifications for a given -- declaration node are associated with that node. -- N_Aspect_Specification -- Sloc points to aspect identifier -- Identifier aspect identifier -- Aspect_Rep_Item -- Expression (set to Empty if none) -- Entity entity to which the aspect applies -- Next_Rep_Item -- Class_Present Set if 'Class present -- Is_Ignored -- Is_Checked -- Is_Delayed_Aspect -- Is_Disabled -- Is_Boolean_Aspect -- Split_PPC Set if split pre/post attribute -- Aspect_On_Partial_View -- Note: Aspect_Specification is an Ada 2012 feature -- Note: The Identifier serves to identify the aspect involved (it -- is the aspect whose name corresponds to the Chars field). This -- means that the other fields of this identifier are unused, and -- in particular we use the Entity field of this identifier to save -- a copy of the expression for visibility analysis, see spec of -- Sem_Ch13 for full details of this usage. -- In the case of aspects of the form xxx'Class, the aspect identifier -- is for xxx, and Class_Present is set to True. -- Note: When a Pre or Post aspect specification is processed, it is -- broken into AND THEN sections. The left most section has Split_PPC -- set to False, indicating that it is the original specification (e.g. -- for posting errors). For the other sections, Split_PPC is set True. --------------------------------------------- -- 13.4 Enumeration representation clause -- --------------------------------------------- -- ENUMERATION_REPRESENTATION_CLAUSE ::= -- for first_subtype_LOCAL_NAME use ENUMERATION_AGGREGATE; -- In Ada 83, the name must be a direct name -- N_Enumeration_Representation_Clause -- Sloc points to FOR -- Identifier direct name -- Array_Aggregate -- Next_Rep_Item --------------------------------- -- 13.4 Enumeration aggregate -- --------------------------------- -- ENUMERATION_AGGREGATE ::= ARRAY_AGGREGATE ------------------------------------------ -- 13.5.1 Record representation clause -- ------------------------------------------ -- RECORD_REPRESENTATION_CLAUSE ::= -- for first_subtype_LOCAL_NAME use -- record [MOD_CLAUSE] -- {COMPONENT_CLAUSE} -- end record; -- Gigi restriction: Mod_Clause is always Empty (if present it is -- replaced by a corresponding Alignment attribute definition clause). -- Note: Component_Clauses can include pragmas -- N_Record_Representation_Clause -- Sloc points to FOR -- Identifier direct name -- Mod_Clause (set to Empty if no mod clause present) -- Component_Clauses -- Next_Rep_Item ------------------------------ -- 13.5.1 Component clause -- ------------------------------ -- COMPONENT_CLAUSE ::= -- component_LOCAL_NAME at POSITION -- range FIRST_BIT .. LAST_BIT; -- N_Component_Clause -- Sloc points to AT -- Component_Name points to Name or Attribute_Reference -- Position -- First_Bit -- Last_Bit ---------------------- -- 13.5.1 Position -- ---------------------- -- POSITION ::= static_EXPRESSION ----------------------- -- 13.5.1 First_Bit -- ----------------------- -- FIRST_BIT ::= static_SIMPLE_EXPRESSION ---------------------- -- 13.5.1 Last_Bit -- ---------------------- -- LAST_BIT ::= static_SIMPLE_EXPRESSION -------------------------- -- 13.8 Code statement -- -------------------------- -- CODE_STATEMENT ::= QUALIFIED_EXPRESSION; -- Note: in GNAT, the qualified expression has the form -- Asm_Insn'(Asm (...)); -- See package System.Machine_Code in file s-maccod.ads for details on -- the allowed parameters to Asm. There are two ways this node can -- arise, as a code statement, in which case the expression is the -- qualified expression, or as a result of the expansion of an intrinsic -- call to the Asm or Asm_Input procedure. -- N_Code_Statement -- Sloc points to first token of the expression -- Expression -- Note: package Exp_Code contains an abstract functional interface -- for use by Gigi in accessing the data from N_Code_Statement nodes. ------------------------ -- 13.12 Restriction -- ------------------------ -- RESTRICTION ::= -- restriction_IDENTIFIER -- | restriction_parameter_IDENTIFIER => EXPRESSION -- There is no explicit node for restrictions. Instead the restriction -- appears in normal pragma syntax as a pragma argument association, -- which has the same syntactic form. -------------------------- -- B.2 Shift Operators -- -------------------------- -- Calls to the intrinsic shift functions are converted to one of -- the following shift nodes, which have the form of normal binary -- operator names. Note that for a given shift operation, one node -- covers all possible types, as for normal operators. -- Note: it is perfectly permissible for the expander to generate -- shift operation nodes directly, in which case they will be analyzed -- and parsed in the usual manner. -- Sprint syntax: shift-function-name!(expr, count) -- Note: the Left_Opnd field holds the first argument (the value to -- be shifted). The Right_Opnd field holds the second argument (the -- shift count). The Chars field is the name of the intrinsic function. -- N_Op_Rotate_Left -- Sloc points to the function name -- plus fields for binary operator -- plus fields for expression -- Shift_Count_OK -- N_Op_Rotate_Right -- Sloc points to the function name -- plus fields for binary operator -- plus fields for expression -- Shift_Count_OK -- N_Op_Shift_Left -- Sloc points to the function name -- plus fields for binary operator -- plus fields for expression -- Shift_Count_OK -- N_Op_Shift_Right_Arithmetic -- Sloc points to the function name -- plus fields for binary operator -- plus fields for expression -- Shift_Count_OK -- N_Op_Shift_Right -- Sloc points to the function name -- plus fields for binary operator -- plus fields for expression -- Shift_Count_OK -- Note: N_Op_Rotate_Left, N_Op_Rotate_Right, N_Shift_Right_Arithmetic -- never appear in the expanded tree if Modify_Tree_For_C mode is set. -- Note: For N_Op_Shift_Left and N_Op_Shift_Right, the right operand is -- always less than the word size if Modify_Tree_For_C mode is set. -------------------------- -- Obsolescent Features -- -------------------------- -- The syntax descriptions and tree nodes for obsolescent features are -- grouped together, corresponding to their location in appendix I in -- the RM. However, parsing and semantic analysis for these constructs -- is located in an appropriate chapter (see individual notes). --------------------------- -- J.3 Delta Constraint -- --------------------------- -- Note: the parse routine for this construct is located in section -- 3.5.9 of Par-Ch3, and semantic analysis is in Sem_Ch3, which is -- where delta constraint logically belongs. -- DELTA_CONSTRAINT ::= DELTA static_EXPRESSION [RANGE_CONSTRAINT] -- N_Delta_Constraint -- Sloc points to DELTA -- Delta_Expression -- Range_Constraint (set to Empty if not present) -------------------- -- J.7 At Clause -- -------------------- -- AT_CLAUSE ::= for DIRECT_NAME use at EXPRESSION; -- Note: the parse routine for this construct is located in Par-Ch13, -- and the semantic analysis is in Sem_Ch13, where at clause logically -- belongs if it were not obsolescent. -- Note: in Ada 83 the expression must be a simple expression -- Gigi restriction: This node never appears, it is rewritten as an -- address attribute definition clause. -- N_At_Clause -- Sloc points to FOR -- Identifier -- Expression --------------------- -- J.8 Mod clause -- --------------------- -- MOD_CLAUSE ::= at mod static_EXPRESSION; -- Note: the parse routine for this construct is located in Par-Ch13, -- and the semantic analysis is in Sem_Ch13, where mod clause logically -- belongs if it were not obsolescent. -- Note: in Ada 83, the expression must be a simple expression -- Gigi restriction: this node never appears. It is replaced -- by a corresponding Alignment attribute definition clause. -- Note: pragmas can appear before and after the MOD_CLAUSE since -- its name has "clause" in it. This is rather strange, but is quite -- definitely specified. The pragmas before are collected in the -- Pragmas_Before field of the mod clause node itself, and pragmas -- after are simply swallowed up in the list of component clauses. -- N_Mod_Clause -- Sloc points to AT -- Expression -- Pragmas_Before Pragmas before mod clause (No_List if none) -------------------- -- Semantic Nodes -- -------------------- -- These semantic nodes are used to hold additional semantic information. -- They are inserted into the tree as a result of semantic processing. -- Although there are no legitimate source syntax constructions that -- correspond directly to these nodes, we need a source syntax for the -- reconstructed tree printed by Sprint, and the node descriptions here -- show this syntax. ----------------- -- Call_Marker -- ----------------- -- This node is created during the analysis/resolution of entry calls, -- requeues, and subprogram calls. It performs several functions: -- * Call markers provide a uniform model for handling calls by the -- ABE mechanism, regardless of whether expansion took place. -- * The call marker captures the target of the related call along -- with other attributes which are either unavailable or expensive -- to recompute once analysis, resolution, and expansion are over. -- * The call marker aids the ABE Processing phase by signaling the -- presence of a call in case the original call was transformed by -- expansion. -- * The call marker acts as a reference point for the insertion of -- run-time conditional ABE checks or guaranteed ABE failures. -- Sprint syntax: #target# -- The Sprint syntax shown above is not enabled by default -- N_Call_Marker -- Sloc points to Sloc of original call -- Target -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Is_Source_Call -- Is_Declaration_Level_Node -- Is_Dispatching_Call -- Is_Preelaborable_Call -- Is_Known_Guaranteed_ABE ------------------------ -- Compound Statement -- ------------------------ -- This node is created by the analyzer/expander to handle some -- expansion cases where a sequence of actions needs to be captured -- within a single node (which acts as a container and allows the -- entire list of actions to be moved around as a whole) appearing -- in a sequence of statements. -- This is the statement counterpart to the expression node -- N_Expression_With_Actions. -- The required semantics is that the set of actions is executed in -- the order in which it appears, as though they appeared by themselves -- in the enclosing list of declarations or statements. Unlike what -- happens when using an N_Block_Statement, no new scope is introduced. -- Note: for the time being, this is used only as a transient -- representation during expansion, and all compound statement nodes -- must be exploded back to their constituent statements before handing -- the tree to the back end. -- Sprint syntax: do -- action; -- action; -- ... -- action; -- end; -- N_Compound_Statement -- Actions -------------- -- Contract -- -------------- -- This node is used to hold the various parts of an entry, subprogram -- [body] or package [body] contract, in particular: -- Abstract states declared by a package declaration -- Contract cases that apply to a subprogram -- Dependency relations of inputs and output of a subprogram -- Global annotations classifying data as input or output -- Initialization sequences for a package declaration -- Pre- and postconditions that apply to a subprogram -- The node appears in an entry and [generic] subprogram [body] entity. -- Sprint syntax: as the node should not appear in the tree, but -- only attached to an entry or [generic] subprogram -- entity. -- N_Contract -- Sloc points to the subprogram's name -- Pre_Post_Conditions (set to Empty if none) -- Contract_Test_Cases (set to Empty if none) -- Classifications (set to Empty if none) -- Is_Expanded_Contract -- Pre_Post_Conditions contains a collection of pragmas that correspond -- to pre- and postconditions associated with an entry or a subprogram -- [body or stub]. The pragmas can either come from source or be the -- byproduct of aspect expansion. Currently the following pragmas appear -- in this list: -- Post -- Postcondition -- Pre -- Precondition -- Refined_Post -- The ordering in the list is in LIFO fashion. -- Note that there might be multiple preconditions or postconditions -- in this list, either because they come from separate pragmas in the -- source, or because a Pre (resp. Post) aspect specification has been -- broken into AND THEN sections. See Split_PPC for details. -- In GNATprove mode, the inherited classwide pre- and postconditions -- (suitably specialized for the specific type of the overriding -- operation) are also in this list. -- Contract_Test_Cases contains a collection of pragmas that correspond -- to aspects/pragmas Contract_Cases, Exceptional_Cases, Test_Case and -- Subprogram_Variant. The ordering in the list is in LIFO fashion. -- Classifications contains pragmas that either declare, categorize, or -- establish dependencies between subprogram or package inputs and -- outputs. Currently the following pragmas appear in this list: -- Abstract_States -- Always_Terminates -- Async_Readers -- Async_Writers -- Constant_After_Elaboration -- Depends -- Effective_Reads -- Effective_Writes -- Extensions_Visible -- Global -- Initial_Condition -- Initializes -- Part_Of -- Refined_Depends -- Refined_Global -- Refined_States -- Volatile_Function -- The ordering is in LIFO fashion. ------------------- -- Expanded Name -- ------------------- -- The N_Expanded_Name node is used to represent a selected component -- name that has been resolved to an expanded name. The semantic phase -- replaces N_Selected_Component nodes that represent names by the use -- of this node, leaving the N_Selected_Component node used only when -- the prefix is a record or protected type. -- The fields of the N_Expanded_Name node are laid out identically -- to those of the N_Selected_Component node, allowing conversion of -- an expanded name node to a selected component node to be done -- easily, see Sinfo.CN.Change_Selected_Component_To_Expanded_Name. -- There is no special sprint syntax for an expanded name -- N_Expanded_Name -- Sloc points to the period -- Chars copy of Chars field of selector name -- Prefix -- Selector_Name -- Entity -- Associated_Node -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Has_Private_View (set in generic units) -- Has_Secondary_Private_View (set in generic units) -- Redundant_Use -- Atomic_Sync_Required -- plus fields for expression ----------------------------- -- Expression With Actions -- ----------------------------- -- This node is created by the analyzer/expander to handle some -- expansion cases, notably short-circuit forms where there are -- actions associated with the right-hand side operand. -- The N_Expression_With_Actions node represents an expression with -- an associated set of actions (which are executable statements and -- declarations, as might occur in a handled statement sequence). -- The required semantics is that the set of actions is executed in -- the order in which it appears just before the expression is -- evaluated (and these actions must only be executed if the value -- of the expression is evaluated). The node is considered to be -- a subexpression, whose value is the value of the Expression after -- executing all the actions. -- If the actions contain declarations, then these declarations may -- be referenced within the expression. -- (AI12-0236-1): In Ada 2022, for a declare_expression, the parser -- generates an N_Expression_With_Actions. Declare_expressions have -- various restrictions, which we do not enforce on -- N_Expression_With_Actions nodes that are generated by the -- expander. The two cases can be distinguished by looking at -- Comes_From_Source. -- ???Perhaps we should change the name of this node to -- N_Declare_Expression, and perhaps we should change the Sprint syntax -- to match the RM syntax for declare_expression. -- Sprint syntax: do -- action; -- action; -- ... -- action; -- in expression end -- N_Expression_With_Actions -- Actions -- Expression -- plus fields for expression -- Note: In the final generated tree presented to the code generator, -- the actions list is always non-null, since there is no point in this -- node if the actions are Empty. During semantic analysis there are -- cases where it is convenient to temporarily generate an empty actions -- list. This arises in cases where we create such an empty actions -- list, and it may or may not end up being a place where additional -- actions are inserted. The expander removes such empty cases after -- the expression of the node is fully analyzed and expanded, at which -- point it is safe to remove it, since no more actions can be inserted. -- Note: In Modify_Tree_For_C, we never generate any declarations in -- the action list, which can contain only non-declarative statements. -------------------- -- Free Statement -- -------------------- -- The N_Free_Statement node is generated as a result of a call to an -- instantiation of Unchecked_Deallocation. The instantiation of this -- generic is handled specially and generates this node directly. -- Sprint syntax: free expression -- N_Free_Statement -- Sloc is copied from the unchecked deallocation call -- Expression argument to unchecked deallocation call -- Storage_Pool -- Procedure_To_Call -- Actual_Designated_Subtype -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the FREE keyword in the Sprint file output. ------------------- -- Freeze Entity -- ------------------- -- This node marks the point in a declarative part at which an entity -- declared therein becomes frozen. The expander places initialization -- procedures for types at those points. Gigi uses the freezing point -- to elaborate entities that may depend on previous private types. -- See the section in Einfo "Delayed Freezing and Elaboration" for -- a full description of the use of this node. -- The Entity field points back to the entity for the type (whose -- Freeze_Node field points back to this freeze node). -- The Actions field contains a list of declarations and statements -- generated by the expander which are associated with the freeze -- node, and are elaborated as though the freeze node were replaced -- by this sequence of actions. -- Note: the Sloc field in the freeze node references a construct -- associated with the freezing point. This is used for posting -- messages in some error/warning situations, e.g. the case where -- a primitive operation of a tagged type is declared too late. -- Sprint syntax: freeze entity-name [ -- freeze actions -- ] -- N_Freeze_Entity -- Sloc points near freeze point (see above special note) -- Entity -- Access_Types_To_Process (set to No_Elist if none) -- TSS_Elist (set to No_Elist if no associated TSS's) -- Actions (set to No_List if no freeze actions) -- First_Subtype_Link (set to Empty if no link) -- The Actions field holds actions associated with the freeze. These -- actions are elaborated at the point where the type is frozen. -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the FREEZE keyword in the Sprint file output. --------------------------- -- Freeze Generic Entity -- --------------------------- -- The freeze point of an entity indicates the point at which the -- information needed to generate code for the entity is complete. -- The freeze node for an entity triggers expander activities, such as -- build initialization procedures, and backend activities, such as -- completing the elaboration of packages. -- For entities declared within a generic unit, for which no code is -- generated, the freeze point is not equally meaningful. However, in -- Ada 2012 several semantic checks on declarations must be delayed to -- the freeze point, and we need to include such a mark in the tree to -- trigger these checks. The Freeze_Generic_Entity node plays no other -- role, and is ignored by the expander and the back-end. -- Sprint syntax: freeze_generic entity-name -- N_Freeze_Generic_Entity -- Sloc points near freeze point -- Entity -------------------------------- -- Implicit Label Declaration -- -------------------------------- -- An implicit label declaration is created for every occurrence of a -- label on a statement or a label on a block or loop. It is chained -- in the declarations of the innermost enclosing block as specified -- in RM section 5.1 (3). -- The Defining_Identifier is the actual identifier for the statement -- identifier. Note that the occurrence of the label is a reference, NOT -- the defining occurrence. The defining occurrence occurs at the head -- of the innermost enclosing block, and is represented by this node. -- Note: from the grammar, this might better be called an implicit -- statement identifier declaration, but the term we choose seems -- friendlier, since at least informally statement identifiers are -- called labels in both cases (i.e. when used in labels, and when -- used as the identifiers of blocks and loops). -- Note: although this is logically a semantic node, since it does not -- correspond directly to a source syntax construction, these nodes are -- actually created by the parser in a post pass done just after parsing -- is complete, before semantic analysis is started (see Par.Labl). -- Sprint syntax: labelname : label; -- N_Implicit_Label_Declaration -- Sloc points to the << token for a statement identifier, or to the -- LOOP, DECLARE, or BEGIN token for a loop or block identifier -- Defining_Identifier -- Label_Construct -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the label name in the generated declaration. --------------------- -- Itype Reference -- --------------------- -- This node is used to create a reference to an Itype. The only purpose -- is to make sure the Itype is defined if this is the first reference. -- A typical use of this node is when an Itype is to be referenced in -- two branches of an IF statement. In this case it is important that -- the first use of the Itype not be inside the conditional, since then -- it might not be defined if the other branch of the IF is taken, in -- the case where the definition generates elaboration code. -- The Itype field points to the referenced Itype -- Sprint syntax: reference itype-name -- N_Itype_Reference -- Sloc points to the node generating the reference -- Itype -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the REFERENCE keyword in the file output. --------------------- -- Raise xxx Error -- --------------------- -- One of these nodes is created during semantic analysis to replace -- a node for an expression that is determined to definitely raise -- the corresponding exception. -- The N_Raise_xxx_Error node may also stand alone in place -- of a declaration or statement, in which case it simply causes -- the exception to be raised (i.e. it is equivalent to a raise -- statement that raises the corresponding exception). This use -- is distinguished by the fact that the Etype in this case is -- Standard_Void_Type; in the subexpression case, the Etype is the -- same as the type of the subexpression which it replaces. -- If Condition is empty, then the raise is unconditional. If the -- Condition field is non-empty, it is a boolean expression which is -- first evaluated, and the exception is raised only if the value of the -- expression is True. In the unconditional case, the creation of this -- node is usually accompanied by a warning message (unless it appears -- within the right operand of a short-circuit form whose left argument -- is static and decisively eliminates elaboration of the raise -- operation). The condition field can ONLY be present when the node is -- used as a statement form; it must NOT be present in the case where -- the node appears within an expression. -- The exception is generated with a message that contains the -- file name and line number, and then appended text. The Reason -- code shows the text to be added. The Reason code is an element -- of the type Types.RT_Exception_Code, and indicates both the -- message to be added, and the exception to be raised (which must -- match the node type). The value is stored by storing a Uint which -- is the Pos value of the enumeration element in this type. -- Gigi restriction: This expander ensures that the type of the -- Condition field is always Standard.Boolean, even if the type -- in the source is some non-standard boolean type. -- Sprint syntax: [xxx_error "msg"] -- or: [xxx_error when condition "msg"] -- N_Raise_Constraint_Error -- Sloc references related construct -- Condition (set to Empty if no condition) -- Reason -- plus fields for expression -- N_Raise_Program_Error -- Sloc references related construct -- Condition (set to Empty if no condition) -- Reason -- plus fields for expression -- N_Raise_Storage_Error -- Sloc references related construct -- Condition (set to Empty if no condition) -- Reason -- plus fields for expression -- Note: Sloc is copied from the expression generating the exception. -- In the case where a debug source file is generated, the Sloc for -- this node points to the left bracket in the Sprint file output. -- Note: the back end may be required to translate these nodes into -- appropriate goto statements. See description of N_Push/Pop_xxx_Label. --------------------------------------------- -- Optimization of Exception Raise to Goto -- --------------------------------------------- -- In some cases, the front end will determine that any exception raised -- by the back end for a certain exception should be transformed into a -- goto statement. -- There are three kinds of exceptions raised by the back end (note that -- for this purpose we consider gigi to be part of the back end in the -- gcc case): -- 1. Exceptions resulting from N_Raise_xxx_Error nodes -- 2. Exceptions from checks triggered by Do_xxx_Check flags -- 3. Other cases not specifically marked by the front end -- Normally all such exceptions are translated into calls to the proper -- Rcheck_xx procedure, where xx encodes both the exception to be raised -- and the exception message. -- The front end may determine that for a particular sequence of code, -- exceptions in any of these three categories for a particular builtin -- exception should result in a goto, rather than a call to Rcheck_xx. -- The exact sequence to be generated is: -- Local_Raise (exception'Identity); -- goto Label -- The front end marks such a sequence of code by bracketing it with -- push and pop nodes: -- N_Push_xxx_Label (referencing the label) -- ... -- (code where transformation is expected for exception xxx) -- ... -- N_Pop_xxx_Label -- The use of push/pop reflects the fact that such regions can properly -- nest, and one special case is a subregion in which no transformation -- is allowed. Such a region is marked by a N_Push_xxx_Label node whose -- Exception_Label field is Empty. -- N_Push_Constraint_Error_Label -- Sloc references first statement in region covered -- Exception_Label -- N_Push_Program_Error_Label -- Sloc references first statement in region covered -- Exception_Label -- N_Push_Storage_Error_Label -- Sloc references first statement in region covered -- Exception_Label -- N_Pop_Constraint_Error_Label -- Sloc references last statement in region covered -- N_Pop_Program_Error_Label -- Sloc references last statement in region covered -- N_Pop_Storage_Error_Label -- Sloc references last statement in region covered --------------- -- Reference -- --------------- -- For a number of purposes, we need to construct references to objects. -- These references are subsequently treated as normal access values. -- An example is the construction of the parameter block passed to a -- task entry. The N_Reference node is provided for this purpose. It is -- similar in effect to the use of the Unrestricted_Access attribute, -- and like Unrestricted_Access can be applied to objects which would -- not be valid prefixes for the Unchecked_Access attribute (e.g. -- objects which are not aliased, and slices). In addition it can be -- applied to composite type values as well as objects, including string -- values and aggregates. -- Note: we use the Prefix field for this expression so that the -- resulting node can be treated using common code with the attribute -- nodes for the 'Access and related attributes. Logically it would make -- more sense to call it an Expression field, but then we would have to -- special case the treatment of the N_Reference node. -- Note: evaluating a N_Reference node is guaranteed to yield a non-null -- value at run time. Therefore, it is valid to set Is_Known_Non_Null on -- a temporary initialized to a N_Reference node in order to eliminate -- superfluous access checks. -- Sprint syntax: prefix'reference -- N_Reference -- Sloc is copied from the expression -- Prefix -- plus fields for expression -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the quote in the Sprint file output. ---------------- -- SCIL Nodes -- ---------------- -- SCIL nodes are special nodes added to the tree when the CodePeer mode -- is active. They are only generated if SCIL generation is enabled. -- A standard tree-walk will not encounter these nodes even if they -- are present; these nodes are only accessible via the function -- SCIL_LL.Get_SCIL_Node. These nodes have no associated dynamic -- semantics. -- Sprint syntax: [ ] -- No semantic field values are displayed. -- N_SCIL_Dispatch_Table_Tag_Init -- Sloc references a node for a tag initialization -- SCIL_Entity -- -- An N_SCIL_Dispatch_Table_Tag_Init node may be associated (via -- Get_SCIL_Node) with the N_Object_Declaration node corresponding to -- the declaration of the dispatch table for a tagged type. -- N_SCIL_Dispatching_Call -- Sloc references the node of a dispatching call -- SCIL_Target_Prim -- SCIL_Entity -- SCIL_Controlling_Tag -- -- An N_Scil_Dispatching call node may be associated (via Get_SCIL_Node) -- with the N_Procedure_Call_Statement or N_Function_Call node (or a -- rewriting thereof) corresponding to a dispatching call. -- N_SCIL_Membership_Test -- Sloc references the node of a membership test -- SCIL_Tag_Value -- SCIL_Entity -- -- An N_Scil_Membership_Test node may be associated (via Get_SCIL_Node) -- with the N_In node (or a rewriting thereof) corresponding to a -- classwide membership test. -------------------------- -- Unchecked Expression -- -------------------------- -- An unchecked expression is one that must be analyzed and resolved -- with all checks off, regardless of the current setting of scope -- suppress flags. -- Sprint syntax: `(expression) -- Note: this node is always removed from the tree (and replaced by -- its constituent expression) on completion of analysis, so it only -- appears in intermediate trees, and will never be seen by Gigi. -- N_Unchecked_Expression -- Sloc is a copy of the Sloc of the expression -- Expression -- plus fields for expression -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the back quote in the Sprint file output. ------------------------------- -- Unchecked Type Conversion -- ------------------------------- -- An unchecked type conversion node represents the semantic action -- corresponding to a call to an instantiation of Unchecked_Conversion. -- It is generated as a result of actual use of Unchecked_Conversion -- and also by the expander. -- Unchecked type conversion nodes should be created by calling -- Tbuild.Unchecked_Convert_To, rather than by directly calling -- Nmake.Make_Unchecked_Type_Conversion. -- Note: an unchecked type conversion is a variable as far as the -- semantics are concerned, which is convenient for the expander. -- This does not change what Ada source programs are legal, since -- clearly a function call to an instantiation of Unchecked_Conversion -- is not a variable in any case. -- Sprint syntax: subtype-mark!(expression) -- N_Unchecked_Type_Conversion -- Sloc points to related node in source -- Subtype_Mark -- Expression -- Kill_Range_Check -- No_Truncation -- plus fields for expression -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the exclamation in the Sprint file output. ----------------------------------- -- Validate_Unchecked_Conversion -- ----------------------------------- -- The front end does most of the validation of unchecked conversion, -- including checking sizes (this is done after the back end is called -- to take advantage of back-annotation of calculated sizes). -- The front end also deals with specific cases that are not allowed -- e.g. involving unconstrained array types. -- For the case of the standard gigi backend, this means that all -- checks are done in the front end. -- However, in the case of specialized back-ends, in particular the JVM -- backend in the past, additional requirements and restrictions may -- apply to unchecked conversion, and these are most conveniently -- performed in the specialized back-end. -- To accommodate this requirement, for such back ends, the following -- special node is generated recording an unchecked conversion that -- needs to be validated. The back end should post an appropriate -- error message if the unchecked conversion is invalid or warrants -- a special warning message. -- Source_Type and Target_Type point to the entities for the two -- types involved in the unchecked conversion instantiation that -- is to be validated. -- Sprint syntax: validate Unchecked_Conversion (source, target); -- N_Validate_Unchecked_Conversion -- Sloc points to instantiation (location for warning message) -- Source_Type -- Target_Type -- Note: in the case where a debug source file is generated, the Sloc -- for this node points to the VALIDATE keyword in the file output. ------------------------------- -- Variable_Reference_Marker -- ------------------------------- -- This node is created during the analysis of direct or expanded names, -- and the resolution of entry and subprogram calls. It performs several -- functions: -- * Variable reference markers provide a uniform model for handling -- variable references by the ABE mechanism, regardless of whether -- expansion took place. -- * The variable reference marker captures the entity of the variable -- being read or written. -- * The variable reference markers aid the ABE Processing phase by -- signaling the presence of a call in case the original variable -- reference was transformed by expansion. -- Sprint syntax: r#target# -- for a read -- rw#target# -- for a read/write -- w#target# -- for a write -- The Sprint syntax shown above is not enabled by default -- N_Variable_Reference_Marker -- Sloc points to Sloc of original variable reference -- Target -- Is_Elaboration_Checks_OK_Node -- Is_SPARK_Mode_On_Node -- Is_Elaboration_Warnings_OK_Node -- Is_Read -- Is_Write ----------- -- Empty -- ----------- -- Used as the contents of the Nkind field of the dummy Empty node and in -- some other situations to indicate an uninitialized value. -- N_Empty -- Chars is set to No_Name ----------- -- Error -- ----------- -- Used as the contents of the Nkind field of the dummy Error node. -- Has an Etype field, which gets set to Any_Type later on, to help -- error recovery (Error_Posted is also set in the Error node). -- N_Error -- Chars is set to Error_Name -- Etype end Sinfo;