------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- R E S T R I C T -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2021, 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 deals with the implementation of the Restrictions pragma with Aspects; use Aspects; with Namet; use Namet; with Rident; use Rident; with Snames; use Snames; with Table; with Types; use Types; with Uintp; use Uintp; package Restrict is Restrictions : Restrictions_Info := No_Restrictions; -- This variable records restrictions found in any units in the main -- extended unit, and in the case of restrictions checked for partition -- consistency, restrictions found in any with'ed units, parent specs -- etc., since we may as well check as much as we can at compile time. -- These variables should not be referenced directly by clients. Instead -- use Check_Restriction to record a violation of a restriction, and -- Restriction_Active to test if a given restriction is active. Restrictions_Loc : array (All_Restrictions) of Source_Ptr := (others => No_Location); -- Locations of Restrictions pragmas for error message purposes. -- Valid only if corresponding entry in Restrictions is set. A value -- of No_Location is used for implicit restrictions set by another -- pragma, and a value of System_Location is used for restrictions -- set from package Standard by the processing in Targparm. Restriction_Profile_Name : array (All_Restrictions) of Profile_Name; -- Entries in this array are valid only if the corresponding restriction in -- Restrictions is set. The value is the corresponding profile name if the -- restriction was set by a Profile or Profile_Warnings pragma. The value -- is No_Profile in all other cases. Main_Restrictions : Restrictions_Info := No_Restrictions; -- This variable records only restrictions found in any units of the -- main extended unit. These are the variables used for ali file output, -- since we want the binder to be able to accurately diagnose inter-unit -- restriction violations. Restriction_Warnings : Rident.Restriction_Flags := (others => False); -- If one of these flags is set, then it means that violation of the -- corresponding restriction results only in a warning message, not -- in an error message, and the restriction is not otherwise enforced. -- Note that the flags in Restrictions are set to indicate that the -- restriction is set in this case, but Main_Restrictions is never -- set if Restriction_Warnings is set, so this does not look like a -- restriction to the binder. -- The following declarations establish a mapping between restriction -- identifiers, and the names of corresponding restricted library units. type Unit_Entry is record Res_Id : Restriction_Id; Filenm : String (1 .. 8); end record; Unit_Array : constant array (Positive range <>) of Unit_Entry := ( (No_Asynchronous_Control, "a-astaco"), (No_Calendar, "a-calend"), (No_Calendar, "calendar"), (No_Delay, "a-calend"), (No_Delay, "calendar"), (No_Dynamic_Priorities, "a-dynpri"), (No_Finalization, "a-finali"), (No_IO, "a-direct"), (No_IO, "a-direio"), (No_IO, "directio"), (No_IO, "a-sequio"), (No_IO, "sequenio"), (No_IO, "a-ststio"), (No_IO, "a-textio"), (No_IO, "text_io "), (No_IO, "a-witeio"), (No_Task_Attributes_Package, "a-tasatt"), (No_Unchecked_Conversion, "a-unccon"), (No_Unchecked_Conversion, "unchconv"), (No_Unchecked_Deallocation, "a-uncdea"), (No_Unchecked_Deallocation, "unchdeal")); -- The following map has True for all GNAT-defined Restrictions. It is used -- to implement pragma Restrictions (No_Implementation_Restrictions) (which -- is why this restriction itself is excluded from the list). Implementation_Restriction : constant array (All_Restrictions) of Boolean := (Simple_Barriers => True, No_Calendar => True, No_Default_Initialization => True, No_Direct_Boolean_Operators => True, No_Dispatching_Calls => True, No_Dynamic_Accessibility_Checks => True, No_Dynamic_Attachment => True, No_Elaboration_Code => True, No_Enumeration_Maps => True, No_Entry_Calls_In_Elaboration_Code => True, No_Entry_Queue => True, No_Exception_Handlers => True, No_Exception_Propagation => True, No_Exception_Registration => True, No_Finalization => True, No_Fixed_IO => True, No_Implementation_Attributes => True, No_Implementation_Pragmas => True, No_Implicit_Conditionals => True, No_Implicit_Aliasing => True, No_Implicit_Dynamic_Code => True, No_Implicit_Loops => True, No_Initialize_Scalars => True, No_Local_Protected_Objects => True, No_Long_Long_Integers => True, No_Multiple_Elaboration => True, No_Protected_Type_Allocators => True, No_Relative_Delay => True, No_Requeue_Statements => True, No_Secondary_Stack => True, No_Select_Statements => True, No_Standard_Storage_Pools => True, No_Stream_Optimizations => True, No_Streams => True, No_Task_Attributes_Package => True, No_Task_Termination => True, No_Tasking => True, No_Wide_Characters => True, Static_Priorities => True, Static_Storage_Size => True, Pure_Barriers => True, SPARK_05 => True, others => False); -------------------------- -- No_Dependences Table -- -------------------------- -- The following table records entries made by Restrictions pragmas -- that specify a parameter for No_Dependence. Each such pragma makes -- an entry in this table. -- Note: we have chosen to implement this restriction in the "syntactic" -- form, where we do not check that the named package is a language defined -- package, but instead we allow arbitrary package names. The discussion of -- this issue is not complete in the ARG, but the sense seems to be leaning -- in this direction, which makes more sense to us, since it is much more -- useful, and much easier to implement. type ND_Entry is record Unit : Node_Id; -- The unit parameter from the No_Dependence pragma Warn : Boolean; -- True if from Restriction_Warnings, False if from Restrictions Profile : Profile_Name; -- Set to name of profile from which No_Dependence entry came, or to -- No_Profile if a pragma Restriction set the No_Dependence entry. end record; package No_Dependences is new Table.Table ( Table_Component_Type => ND_Entry, Table_Index_Type => Int, Table_Low_Bound => 0, Table_Initial => 200, Table_Increment => 200, Table_Name => "Name_No_Dependences"); ---------------------------- -- No_Use_Of_Entity Table -- ---------------------------- -- The following table records entries made by Restrictions pragmas -- that specify a parameter for No_Use_Of_Entity. Each such pragma makes -- an entry in this table. -- Note: we have chosen to implement this restriction in the "syntactic" -- form, where we allow arbitrary fully qualified names to be specified. type NE_Entry is record Entity : Node_Id; -- The entity parameter from the No_Use_Of_Entity pragma. This is in -- the form of a selected component, since that is the way the parser -- processes it, and we don't further analyze it. Warn : Boolean; -- True if from Restriction_Warnings, False if from Restrictions Profile : Profile_Name; -- Set to name of profile from which No_Use_Of_Entity entry came, or to -- No_Profile if a pragma Restriction set the No_Use_Of_Entity entry. end record; package No_Use_Of_Entity is new Table.Table ( Table_Component_Type => NE_Entry, Table_Index_Type => Int, Table_Low_Bound => 0, Table_Initial => 200, Table_Increment => 200, Table_Name => "Name_No_Use_Of_Entity"); -- Note that in addition to making an entry in this table, we also set the -- Boolean2 flag of the Name_Table entry for the simple name of the entity. -- This is used to avoid most useless searches of this table. ----------------- -- Subprograms -- ----------------- -- Note: several of these subprograms can generate error messages (e.g. -- Check_Restriction). These routines should be called in the analyzer -- rather than the expander, so that the associated error messages are -- correctly generated in semantics only (-gnatc) mode. function Abort_Allowed return Boolean; pragma Inline (Abort_Allowed); -- Tests to see if abort is allowed by the current restrictions settings. -- For abort to be allowed, either No_Abort_Statements must be False, -- or Max_Asynchronous_Select_Nesting must be non-zero. procedure Check_Compiler_Unit (Feature : String; N : Node_Id); -- If unit N is in a unit that has a pragma Compiler_Unit_Warning, then -- a message is posted on node N noting use of the given feature is not -- permitted in the compiler (bootstrap considerations). procedure Check_Compiler_Unit (Feature : String; Loc : Source_Ptr); -- If unit N is in a unit that has a pragma Compiler_Unit_Warning, then a -- message is posted at location Loc noting use of the given feature is not -- permitted in the compiler (bootstrap considerations). procedure Check_Restricted_Unit (U : Unit_Name_Type; N : Node_Id); -- Checks if loading of unit U is prohibited by the setting of some -- restriction (e.g. No_IO restricts the loading of unit Ada.Text_IO). -- If a restriction exists post error message at the given node. procedure Check_Restriction (Msg_Issued : out Boolean; R : Restriction_Id; N : Node_Id; V : Uint := Uint_Minus_1); -- Checks that the given restriction is not set, and if it is set, an -- appropriate message is posted on the given node, in which case -- Msg_Issued is set to True (and False otherwise). Also records the -- violation in the appropriate internal arrays. Note that it is mandatory -- to always use this routine to check if a restriction is violated. Such -- checks must never be done directly by the caller, since otherwise -- violations in the absence of restrictions are not properly recorded. The -- value of V is relevant only for parameter restrictions, and in this case -- indicates the exact count for the violation. If the exact count is not -- known, V is left at its default of -1 which indicates an unknown count. procedure Check_Restriction (R : Restriction_Id; N : Node_Id; V : Uint := Uint_Minus_1); -- Wrapper on Check_Restriction with Msg_Issued, with the out-parameter -- being ignored here. procedure Check_Restriction_No_Dependence (U : Node_Id; Err : Node_Id); -- Called when a dependence on a unit is created (either implicitly, or by -- an explicit WITH clause). U is a node for the unit involved, and Err is -- the node to which an error will be attached if necessary. procedure Check_Restriction_No_Specification_Of_Aspect (N : Node_Id); -- N is the node id for an N_Aspect_Specification, an N_Pragma, or an -- N_Attribute_Definition_Clause. An error message (warning) will be issued -- if a restriction (warning) was previously set for this aspect using -- Set_No_Specification_Of_Aspect. procedure Check_Restriction_No_Use_Of_Attribute (N : Node_Id); -- N denotes an attribute definition clause or an attribute reference. An -- error message (warning) will be issued if a restriction (warning) was -- previously set for this attribute using Set_No_Use_Of_Attribute. procedure Check_Restriction_No_Use_Of_Entity (N : Node_Id); -- N is the node id for an entity reference. An error message (warning) -- will be issued if a restriction (warning) was previously set for this -- entity name using Set_No_Use_Of_Entity. procedure Check_Restriction_No_Use_Of_Pragma (N : Node_Id); -- N is the node of a pragma. An error message (warning) will be issued -- if a restriction (warning) was previously set for this pragma using -- Set_No_Use_Of_Pragma. procedure Check_Elaboration_Code_Allowed (N : Node_Id); -- Tests to see if elaboration code is allowed by the current restrictions -- settings. This function is called by Gigi when it needs to define an -- elaboration routine. If elaboration code is not allowed, an error -- message is posted on the node given as argument. -- WARNING: There is a matching C declaration of this subprogram in fe.h procedure Check_No_Implicit_Aliasing (Obj : Node_Id); -- Obj is a node for which Is_Aliased_View is True, which is being used in -- a context (e.g. 'Access) where no implicit aliasing is allowed if the -- restriction No_Implicit_Aliasing is set. This procedure checks for the -- case where the restriction is active and Obj does not meet the required -- rules for avoiding implicit aliases, and issues a restriction message. procedure Check_Implicit_Dynamic_Code_Allowed (N : Node_Id); -- Tests to see if dynamic code generation (dynamically generated -- trampolines, in particular) is allowed by the current restrictions -- settings. This function is called by Gigi when it needs to generate code -- that generates a trampoline. If not allowed, an error message is posted -- on the node given as argument. -- WARNING: There is a matching C declaration of this subprogram in fe.h procedure Check_No_Implicit_Heap_Alloc (N : Node_Id); -- Equivalent to Check_Restriction (No_Implicit_Heap_Allocations, N). -- Provided for easy use by back end, which has to check this restriction. -- WARNING: There is a matching C declaration of this subprogram in fe.h procedure Check_No_Implicit_Protected_Alloc (N : Node_Id); -- Equivalent to: -- Check_Restriction (No_Implicit_Protected_Object_Allocations, N) -- Provided for easy use by back end, which has to check this restriction. -- WARNING: There is a matching C declaration of this subprogram in fe.h procedure Check_No_Implicit_Task_Alloc (N : Node_Id); -- Equivalent to Check_Restriction (No_Implicit_Task_Allocations, N). -- Provided for easy use by back end, which has to check this restriction. -- WARNING: There is a matching C declaration of this subprogram in fe.h procedure Check_Obsolescent_2005_Entity (E : Entity_Id; N : Node_Id); -- This routine checks if the entity E is one of the obsolescent entries -- in Ada.Characters.Handling in Ada 2005 and No_Obsolescent_Features -- restriction is active. If so an appropriate message is given. N is -- the node on which the message is to be placed. It's a bit kludgy to -- have this highly specialized routine rather than some wonderful general -- mechanism (e.g. a special pragma) to handle this case, but there are -- only six cases, and it is not worth the effort to do something general. procedure Check_Wide_Character_Restriction (E : Entity_Id; N : Node_Id); -- This procedure checks if the No_Wide_Character restriction is active, -- and if so, if N Comes_From_Source, and the root type of E is one of -- [Wide_]Wide_Character or [Wide_]Wide_String, then the restriction -- violation is recorded, and an appropriate message given. function Get_Restriction_Id (N : Name_Id) return Restriction_Id; -- Given an identifier name, determines if it is a valid restriction -- identifier, and if so returns the corresponding Restriction_Id value, -- otherwise returns Not_A_Restriction_Id. function OK_No_Dependence_Unit_Name (N : Node_Id) return Boolean; -- Used in checking No_Dependence argument of pragma Restrictions or -- pragma Restrictions_Warning, or attribute Restriction_Set. Returns -- True if N has the proper form for a unit name, False otherwise. function OK_No_Use_Of_Entity_Name (N : Node_Id) return Boolean; -- Used in checking No_Use_Of_Entity argument of pragma Restrictions or -- pragma Restrictions_Warning, or attribute Restriction_Set. Returns -- True if N has the proper form for an entity name, False otherwise. function No_Dynamic_Accessibility_Checks_Enabled (N : Node_Id) return Boolean; -- Test to see if the current restrictions settings specify that -- No_Dynamic_Accessibility_Checks is activated. -- N is currently unused, but is reserved for future use and debugging -- purposes to provide more context on a node for which an accessibility -- check is being performed or generated (e.g. is N in a predefined unit). function No_Exception_Handlers_Set return Boolean; -- Test to see if current restrictions settings specify that no exception -- handlers are present. This function is called by Gigi when it needs to -- expand an AT END clean up identifier with no exception handler. True -- will be returned if the configurable run-time is activated, and either -- of the restrictions No_Exception_Handlers or No_Exception_Propagation is -- set. In the latter case, the source may contain handlers but they either -- get converted using the local goto transformation or deleted. -- WARNING: There is a matching C declaration of this subprogram in fe.h function No_Exception_Propagation_Active return Boolean; -- Test to see if current restrictions settings specify that no -- exception propagation is activated. -- WARNING: There is a matching C declaration of this subprogram in fe.h function Process_Restriction_Synonyms (N : Node_Id) return Name_Id; -- Id is a node whose Chars field contains the name of a restriction. -- If it is one of synonyms that we allow for historical purposes (for -- list see System.Rident), then the proper official name is returned. function Restriction_Active (R : All_Restrictions) return Boolean; pragma Inline (Restriction_Active); -- Determines if a given restriction is active. This call should only be -- used where the compiled code depends on whether the restriction is -- active. Always use Check_Restriction to record a violation. Note that -- this returns False if we only have a Restriction_Warnings set, since -- restriction warnings should never affect generated code. If you want -- to know if a call to Check_Restriction is needed then use the function -- Restriction_Check_Required instead. function Restriction_Check_Required (R : All_Restrictions) return Boolean; pragma Inline (Restriction_Check_Required); -- Determines if either a Restriction_Warnings or Restrictions pragma has -- been given for the specified restriction. If true, then a subsequent -- call to Check_Restriction is required if the restriction is violated. -- This must not be used to guard code generation that depends on whether -- a restriction is active (see Restriction_Active above). Typically it -- is used to avoid complex code to determine if a restriction is violated, -- executing this code only if needed. function Restricted_Profile return Boolean; -- Tests if set of restrictions corresponding to Restricted_Tasking profile -- is currently in effect (set by pragma Profile, or by an appropriate set -- of individual Restrictions pragmas). Returns True only if all the -- required restrictions are set. procedure Set_Global_No_Tasking; -- Used in call from Sem_Prag when restriction No_Tasking is set in the -- run-time package System or in a configuration pragmas file. procedure Set_Profile_Restrictions (P : Profile_Name; N : Node_Id; Warn : Boolean); -- Sets the set of restrictions associated with the given profile name. N -- is the node of the construct to which error messages are to be attached -- as required. Warn is set True for the case of Profile_Warnings where the -- restrictions are set as warnings rather than legality requirements, and -- is also True for Profile if the Treat_Restrictions_As_Warnings flag is -- set. It is false for Profile if this flag is not set. procedure Set_Restriction (R : All_Boolean_Restrictions; N : Node_Id); -- N is a node (typically a pragma node) that has the effect of setting -- Boolean restriction R. The restriction is set in Restrictions, and -- also in Main_Restrictions if this is the main unit. procedure Set_Restriction (R : All_Parameter_Restrictions; N : Node_Id; V : Integer); -- Similar to the above, except that this is used for the case of a -- parameter restriction, and the corresponding value V is given. procedure Set_Restriction (R : All_Restrictions; N : Node_Id; Warn : Boolean; V : Integer := Integer'First); -- Same as above two, except also takes care of setting the -- Restriction_Warnings flag. V is ignored for Boolean -- restrictions. -- -- If this is the first time we've seen this restriction, the warning flag -- is set to Warn. If this is a second or subsequent time, Warn = False -- wins; that is, errors always trump warnings. In that case, the warning -- flag can be set to False, but never to True. procedure Set_Restriction_No_Dependence (Unit : Node_Id; Warn : Boolean; Profile : Profile_Name := No_Profile); -- Sets given No_Dependence restriction in table if not there already. Warn -- is True if from Restriction_Warnings, or for Restrictions if the flag -- Treat_Restrictions_As_Warnings is set. False if from Restrictions and -- this flag is not set. Profile is set to a non-default value if the -- No_Dependence restriction comes from a Profile pragma. procedure Set_Restriction_No_Specification_Of_Aspect (N : Node_Id; Warn : Boolean); -- N is the node id for an identifier from a pragma Restrictions for the -- No_Specification_Of_Aspect pragma. An error message will be issued if -- the identifier is not a valid aspect name. Warning is set True for the -- case of a Restriction_Warnings pragma specifying this restriction and -- False for a Restrictions pragma specifying this restriction. procedure Set_Restriction_No_Specification_Of_Aspect (A_Id : Aspect_Id); -- Version used by Get_Target_Parameters (via Tbuild) procedure Set_Restriction_No_Use_Of_Attribute (N : Node_Id; Warn : Boolean); -- N is the node id for the identifier in a pragma Restrictions for -- No_Use_Of_Attribute. Caller has verified that this is a valid attribute -- designator. procedure Set_Restriction_No_Use_Of_Attribute (A_Id : Attribute_Id); -- Version used by Get_Target_Parameters (via Tbuild) procedure Set_Restriction_No_Use_Of_Entity (Entity : Node_Id; Warn : Boolean; Profile : Profile_Name := No_Profile); -- Sets given No_Use_Of_Entity restriction in table if not there already. -- Warn is True if from Restriction_Warnings, or for Restrictions if the -- flag Treat_Restrictions_As_Warnings is set. False if from Restrictions -- and this flag is not set. Profile is set to a non-default value if the -- No_Dependence restriction comes from a Profile pragma. This procedure -- also takes care of setting the Boolean2 flag of the simple name for -- the entity (to optimize table searches). procedure Set_Restriction_No_Use_Of_Pragma (N : Node_Id; Warn : Boolean); -- N is the node id for the identifier in a pragma Restrictions for -- No_Use_Of_Pragma. Caller has verified that this is a valid pragma id. procedure Set_Restriction_No_Use_Of_Pragma (A_Id : Pragma_Id); -- Version used in call from Get_Target_Parameters (via Tbuild). function Tasking_Allowed return Boolean; pragma Inline (Tasking_Allowed); -- Tests if tasking operations are allowed by the current restrictions -- settings. For tasking to be allowed Max_Tasks must be non-zero. function Global_No_Tasking return Boolean; -- Returns True if the restriction No_Tasking is set in the run-time -- package System or in a configuration pragmas file. ---------------------------------------------- -- Handling of Boolean Compilation Switches -- ---------------------------------------------- -- The following declarations are used for proper saving and restoring of -- restrictions for separate compilation units. There are two cases: -- For partition-wide restrictions, we just let the restrictions pragmas -- pile up, and we never reset them. We might as well detect what we can -- at compile time. If e.g. a with'ed unit has a restriction for one of -- the partition-wide restrictions, then the binder will enforce it on -- all units in the partition, including the unit with the WITH. Although -- it would not be wrong to leave this till bind time, we might as well -- flag it earlier at compile time. -- For non-partition-wide restrictions, we have quite a different state -- of affairs. Here it would be quite wrong to carry a restriction from -- a with'ed unit to another with'ed unit, or from a package spec to the -- package body. This means that we have to reset these non-partition -- wide restrictions at the start of each separate compilation unit. For -- units in the extended main program, we need to reset them all to the -- values set by the configuration pragma file(s). For units not in the -- extended main program, e.g. with'ed units, we might as well reset all -- of these restrictions to off (False). The actual initial values will -- be taken from the config files active when those units are compiled -- as main units. type Save_Cunit_Boolean_Restrictions is private; -- Type used for saving and restoring compilation unit restrictions. function Cunit_Boolean_Restrictions_Save return Save_Cunit_Boolean_Restrictions; -- This function saves the compilation unit restriction settings, leaving -- them unchanged. This is used e.g. at the start of processing a context -- clause, so that the main unit restrictions can be restored after all -- the with'ed units have been processed. procedure Cunit_Boolean_Restrictions_Restore (R : Save_Cunit_Boolean_Restrictions); -- This is the corresponding restore procedure to restore restrictions -- previously saved by Cunit_Boolean_Restrictions_Save. However it does -- not reset No_Elaboration_Code, this stays set if it was set before -- the call, and also if it is set before the call, then the Config -- setting is also updated to include this restriction. This is what -- implements the special handling of No_Elaboration_Code. procedure Save_Config_Cunit_Boolean_Restrictions; -- This saves the current compilation unit restrictions in an internal -- variable, and leaves them unchanged. This is called immediately after -- processing the configuration file pragmas, to record the restrictions -- set by these configuration file pragmas. procedure Restore_Config_Cunit_Boolean_Restrictions; -- This restores the value saved by the previous call to save config values -- saved by Save_Config_Cunit_Boolean_Restrictions. It is called at the -- start of processing a new unit that is part of the main sources (e.g. -- a package spec when the main unit is a package body). procedure Reset_Cunit_Boolean_Restrictions; -- Turns off all non-partition-wide boolean restrictions procedure Add_To_Config_Boolean_Restrictions (R : Restriction_Id); -- Add specified restriction to stored configuration boolean restrictions. -- This is used for handling the special case of No_Elaboration_Code. private type Save_Cunit_Boolean_Restrictions is array (Cunit_Boolean_Restrictions) of Boolean; -- Type used for saving and restoring compilation unit restrictions. -- See Compilation_Unit_Restrictions_[Save|Restore] subprograms. end Restrict;