exp_ch4.adb (Expand_Allocator_Expression): When an initialized allocator's designated type is a class-wide type...

2005-06-14  Gary Dismukes  <dismukes@adacore.com>
	    Javier Miranda  <miranda@adacore.com>
	    Ed Schonberg  <schonberg@adacore.com>
	    Hristian Kirtchev  <kirtchev@adacore.com>

	* exp_ch4.adb (Expand_Allocator_Expression): When an initialized
	allocator's designated type is a class-wide type, and compiling for
	Ada 2005, emit a run-time check that the accessibility level of the
	type given in the allocator's expression is not deeper than the level
	of the allocator's access type.

	(Tagged_Membership): Modified to gives support to abstract interface
	types.

	* a-tags.ads, a-tags.adb (type Type_Specific_Data): Add component
	Access_Level.
	(Descendant_Tag): New predefined function
	(Is_Descendant_At_Same_Level): New predefined function
	(Get_Access_Level): New private function
	(Set_Access_Level): New private procedure
	(IW_Membership): New function. Given the tag of an object and the tag
	associated with an interface, evaluate if the object implements the
	interface.
	(Register_Interface_Tag): New procedure used to initialize the table of
	interfaces used by the IW_Membership function.
	(Set_Offset_To_Top): Initialize the Offset_To_Top field in the prologue
	of the dispatch table.
	(Inherit_TSD): Modified to copy the table of ancestor tags plus the
	table of interfaces of the parent.
	(Expanded_Name): Raise Tag_Error if the passed tag equals No_Tag.
	(External_Tag): Raise Tag_Error if the passed tag equals No_Tag.
	(Parent_Tag): Return No_Tag in the case of a root-level tagged type,
	and raise Tag_Error if the passed tag equalis No_Tag, to conform with
	Ada 2005 semantics for the new predefined function.

	* exp_attr.adb (Expand_N_Attribute, case Attribute_Input): Generate
	call to Descendant_Tag rather than Internal_Tag.
	(Expand_N_Attribute, case Attribute_Output): Emit a check to ensure that
	the accessibility level of the attribute's Item parameter is not deeper
	than the level of the attribute's prefix type. Tag_Error is raised if
	the check fails. The check is only emitted for Ada_05.
	(Find_Stream_Subprogram): If a TSS exists on the type itself for the
	requested stream attribute, use it.
	(Expand_N_Attribute_Reference): If the designated type is an interface
	then rewrite the referenced object as a conversion to force the
	displacement of the pointer to the secondary dispatch table.
	(Expand_N_Attribute_Reference, case 'Constrained): Return false if this
	is a dereference of an object with a constrained partial view.

	* exp_ch5.adb (Expand_N_Return_Statement): When a function's result
	type is a class-wide type, emit a run-time check that the accessibility
	level of the returned object is not deeper than the level of the
	function's master (only when compiling for Ada 2005).

	* exp_disp.ads, exp_disp.adb (Ada_Actions, Action_Is_Proc,
	Action_Nb_Arg): Add entries for new Get_Access_Level and
	Set_Access_Level routines in these tables.
	(Make_DT): Generate a call to set the accessibility level of the
	tagged type in its TSD.
	(Make_DT): Code cleanup. The functionality of generating all the
	secondary dispatch tables has been moved to freeze_record_type.
	(Make_Abstract_Interface_DT): Minor code cleanup.
	(Set_All_DT_Position): Code cleanup. As part of the code cleanup
	this subprogram implements a new algorithm that provides the
	same functionality and it is more clear in case of primitives
	associated with abstract interfaces.
	(Set_All_Interfaces_DTC_Entity): Removed. As part of the code
	clean up, the functionality of this subprogram is now provided
	by Set_All_DT_Position.
	(Write_DT): New subprogram: a debugging procedure designed to be called
	within gdb to display the dispatch tables associated with a tagged
	type.
	(Collect_All_Interfaces): New subprogram that collects the whole list
	of interfaces that are directly or indirectly implemented by a tagged
	type.
	(Default_Prim_Op_Position): New subprogram that returns the fixed
	position in the dispatch table of the default primitive operations.
	(Expand_Interface_Actuals): New subprogram to generate code that
	displaces all the actuals corresponding to class-wide interfaces to
	reference the interface tag of the actual object.
	(Expand_Interface_Conversion): New subprogram. Reference the base of
	the object to give access to the interface tag associated with the
	secondary dispatch table.
	(Expand_Interface_Thunk): New subprogram that generates the code of the
	thunk. This is required for compatibility with the C+ ABI.
	(Make_Abstract_Interface_DT): New subprogram that generate the
	declarations for the secondary dispatch tables associated with an
	abstract interface.
	(Set_All_Interfaces_DTC_Entity): New subprogram that sets the DTC_Entity
	attribute for each primitive operation covering interface subprograms
	(Expand_Dispatching_Call, Fill_DT_Entry, Make_DT, Set_All_DT_Position):
	These subprograms were upgraded to give support to abstract interfaces

	* rtsfind.ads (type RE_Id): Add RE_Descendant_Tag,
	RE_Is_Descendant_At_Same_Level, RE_Get_Access_Level, and
	RE_Set_Access_Level.
	(RE_Unit_Table): Add entries for new Ada.Tags operations.
	Add support to call the followig new run-time subprograms:
	IW_Membership, Register_Interface_Tag, and Set_Offset_To_Top

	* sem_ch3.adb (Constant_Redeclaration): Allow a deferred constant to
	match its full declaration when both have an access definition with
	statically matching designated subtypes.
	(Analyze_Component_Declaration): Delete commented out code that was
	incorrectly setting the scope of an anonymous access component's type.
	(Process_Discriminants): Set Is_Local_Anonymous_Access for the type of
	an access discriminant when the containing type is nonlimited.
	(Make_Incomplete_Type_Declaration): Create an incomplete type
	declaration for a record type that includes self-referential access
	components.
	(Check_Anonymous_Access_Types): Before full analysis of a record type
	declaration, create anonymous access types for each self-referential
	access component.
	(Analyze_Component_Declaration, Array_Type_Declaration): Indicate that
	an access component in this context is a Local_Anonymous_Access, for
	proper accessibility checks.
	(Access_Definition): Set properly the scope of the anonymous access type
	created for a stand-alone access object.
	(Find_Type_Of_Object): An object declaration may be given with an access
	definition.
	(Complete_Subprograms_Derivation): New subprogram used to complete
	type derivation of private tagged types implementing interfaces.
	In this case some interface primitives may have been overriden
	with the partial-view and, instead of re-calculating them, they
	are included in the list of primitive operations of the full-view.
	(Build_Derived_Record_Type): Modified to give support to private
	types implemening interfaces.
	(Access_Definition): Reject ALL on anonymous access types.
	(Build_Derived_Record_Type): In the case of Ada 2005, allow a tagged
	type derivation to occur at a deeper accessibility level than the
	parent type.
	For the case of derivation within a generic body however, disallow the
	derivation if the derived type has an ancestor that is a formal type
	declared in the formal part of an enclosing generic.
	(Analyze_Object_Declaration): For protected objects, remove the check
	that they cannot contain interrupt handlers if not declared at library
	level.
	(Add_Interface_Tag_Components): New subprogram to add the tag components
	corresponding to all the abstract interface types implemented by a
	record type or a derived record type.
	(Analyze_Private_Extension_Declaration, Build_Derived_Record_Type,
	Derived_Type_Declaration, Find_Type_Name, Inherit_Components,
	Process_Full_View, Record_Type_Declaration): Modified to give
	support to abstract interface types
	(Collect_Interfaces): New subprogram that collects the list of
	interfaces that are not already implemented by the ancestors
	(Process_Full_View): Set flag Has_Partial_Constrained_View appropriately
	when partial view has no discriminants and full view has defaults.
	(Constrain_Access): Reject a constraint on a general access type
	if the discriminants of the designated type have defaults.
	(Access_Subprogram_Declaration): Associate the Itype node with the inner
	full-type declaration or subprogram spec. This is required to handle
	nested anonymous declarations.
	(Analyze_Private_Extension_Declaration, Build_Derived_Record_Type,
	Derived_Type_Declaration, Find_Type_Name, Inherit_Components,
	Process_Full_View, Record_Type_Declaration): Modified to give
	support to abstract interface types
	(Derive_Subprograms): Addition of a new formal to indicate if
	we are in the case of an abstact-interface derivation
	(Find_Type_Of_Subtype_Indic): Moved from the body of the package
	to the specification because it is requied to analyze all the
	identifiers found in a list of interfaces

	* debug.adb: Complete documentation of flag "-gnatdZ"

	* exp_ch3.adb: Implement config version of persistent_bss pragma
	(Check_Stream_Attributes): Use Stream_Attribute_Available instead of
	testing for TSS presence to properly enforce visibility rules.
	(Freeze_Record_Type): Code cleanup. Modified to call the subprogram
	Make_Abstract_Interfaces_DT to generate the secondary tables
	associated with abstract interfaces.
	(Build_Init_Procedure): Modified to initialize all the tags
	corresponding.
	(Component_Needs_Simple_Initialization): Similar to other tags,
	interface tags do not need initialization.
	(Freeze_Record_Type): Modified to give support to abstract interface
	types.
	(Expand_N_Object_Declaration): Do not generate an initialization for
	a scalar temporary marked as internal.

	* exp_ch6.adb (Add_Simple_Call_By_Copy_Code): Handle properly an
	in-out parameter that is a component in an initialization procedure,
	whose constraint might depend on discriminants, and that may be
	misaligned because of packing or representation clauses.
	(Is_Legal_Copy): New predicate to determine whether a possibly
	misaligned in-out actual can actually be passed by copy/return. This
	is an error in case the type is by_reference, and a warning if this is
	the consequence of a DEC import pragma on the subprogram.
	(Expand_Call, Freeze_Subprogram): Modified to give support to abstract
	interface types
	(Expand_Inlined_Call): Mark temporary generated for the return value as
	internal, so that no useless scalar normalization is generated for it.
	(Expand_N_Subprogram_Declaration): Save unanalyzed body so calls to
	null procedure can always be inlined.
	(Expand_N_Subprogram_Declaration): If this is the declaration of a null
	procedure, generate an explicit empty body for it.

	* exp_util.ads, exp_util.adb (Find_Interface_ADT): New subprogram.
	Given a type implementing an interface, returns the corresponding
	access_disp_table value.
	(Find_Interface_Tag): New subprogram. Given a type implementing an
	interface, returns the record component containing the tag of the
	interface.
	(Find_Interface_Tag): New overloaded subprogram. Subsidiary to the
	previous ones that return the corresponding tag and access_disp_table
	entities.
	(Is_Predefined_Dispatching_Operation): Determines if a subprogram
	is a predefined primitive operation.
	(Expand_Subtype_From_Expr): If the expression is a selected component
	within an initialization procedure, compute its actual subtype, because
	the component may depend on the discriminants of the enclosing record.

	* i-cpp.ads, i-cpp.adb:
	This package has been left available for compatibility with previous
	versions of the frontend. As part of the new layout this is now a
	dummy package that uses declarations available at a-tags.ads

	* par-ch3.adb (P_Identifier_Declarations): Give an error for use of
	"constant access" and "aliased [constant] access" when not compiling
	with -gnat05.
	Suppress Ada 2005 keyword warning if -gnatwY used
	(P_Identifier_Declarations): Add support for object declarations with
	access definitions.
	(Private_Extension_Declaration): Complete the documentation
	(P_Derived_Type_Def_Or_Private_Ext_Decl): Fill the inteface_list
	attribute in case of private extension declaration
	(P_Type_Declaration): Mark as "abstract" the type declarations
	corresponding with protected, synchronized and task interfaces
	(P_Declarative_Items): "not" and "overriding" are overriding indicators
	for a subprogram or instance declaration.

	* sem_ch12.adb (Analyze_Subprogram_Instantiation): Verify that an
	instantiation that is a dispatching operation has controlling access
	parameters that are null excluding.
	Save and restore Ada_Version_Explicit, for implementation of AI-362
	(Validate_Derived_Type_Instance): Add check for abstract interface
	types.
	(Analyze_Formal_Package): Establish Instantiation source for the copy of
	the generic that is created to represent the formal package.
	(Analyze_Package_Instantiation): Instantiate body immediately if the
	package is a predefined unit that contains inlined subprograms, and
	we are compiling for a Configurable_Run_Time.
	(Instantiate_Formal_Subprogram): Indicate that null default subprogram
	If the program has a null default, generate an empty body for it.

	* sem_ch6.adb, sem_ch9.adb (Analyze_Subprograms_Declaration): Update
	error message condition, null procedures are correctly detected now.
	(New_Overloaded_Entity): Bypass trivial overriding indicator check
	for subprograms in the context of protected types. Instead, the
	indicator is examined in Sem_Ch9 while analysing the subprogram
	declaration.
	(Check_Overriding_Indicator): Check consistency of overriding indicator
	on subprogram stubs as well.
	(Analyze_Subprogram_Declaration): Diagnose null procedures declared at
	the library level.
	(Analize_Subprogram_Specification): When analyzing a subprogram in which
	the type of the first formal is a concurrent type, replace this type
	by the corresponding record type.
	(Analyze_Subprogram_Body): Undo the previous work.
	(Analyze_Procedure_Call): If the call has the form Object.Op, the
	analysis of the prefix ends up analyzing the call itself, after which
	we are done.
	(Has_Interface_Formals): New subprogram subsidiary to analyze
	subprogram_specification that returns true if some non
	class-wide interface subprogram is found
	(New_Overloaded_Entity): Modified to give support to abstract
	interface types
	(Conforming_Types): In Ada 2005 mode, conformance checking of anonymous
	access to subprograms must be recursive.
	(Is_Unchecked_Conversion): Improve the test that recognizes
	instantiations of Unchecked_Conversion, and allows them in bodies that
	are to be inlined by the front-end. When the body comes from an
	instantiation, a reference to Unchecked_Conversion will be an
	Expanded_Name, even though the body has not been analyzed yet.
	Replace Is_Overriding and Not_Overriding in subprogram_indication with
	Must_Override and Must_Not_Override, to better express intent of AI.
	(Analyze_Subprogram_Body): If an overriding indicator is given, check
	that it is consistent with the overrinding status of the subprogram
	at this point.
	(Analyze_Subprogram_Declaration): Indicate that a null procedure is
	always inlined.
	If the subprogram is a null procedure, indicate that it does not need
	a completion.

	* sem_disp.adb (Check_Controlling_Type): Give support to entities
	available through limited-with clauses.
	(Check_Dispatching_Operation): A stub acts like a body, and therefore is
	allowed as the last primitive of a tagged type if it has no previous
	spec.
	(Override_Dispatching_Operation, Check_Dispatching_Operation): Modified
	to give support to abstract interface types

	* sem_res.adb (Valid_Conversion): Perform an accessibility level check
	in the case where the target type is an anonymous access type of an
	object or component (that is, when Is_Local_Anonymous_Access is true).
	Prevent the special checks for conversions of access discriminants in
	the case where the discriminant belongs to a nonlimited type, since
	such discriminants have their accessibility level defined in the same
	way as a normal component of an anonymous access type.
	(Resolve_Allocator): When an allocator's designated type is a class-wide
	type, check that the accessibility level of type given in the
	allocator's expression or subtype indication is not statically deeper
	than the level of the allocator's access type.
	(Check_Discriminant_Use): Diagnose discriminant given by an expanded
	name in a discriminant constraint of a record component.
	(Resolve_Explicit_Dereference): Do not check whether the type is
	incomplete when the dereference is a use of an access discriminant in
	an initialization procedure.
	(Resolve_Type_Conversion): Handle conversions to abstract interface
	types.
	(Valid_Tagged_Conversion): The conversion of a tagged type to an
	abstract interface type is always valid.
	(Valid_Conversion): Modified to give support to abstract interface types
	(Resolve_Actuals): Enable full error reporting on view conversions
	between unrelated by_reference array types.
	The rule for view conversions of arrays with aliased components is
	weakened in Ada 2005.
	Call to obsolescent subprogram is now considered to be a violation of
	pragma Restrictions (No_Obsolescent_Features).
	(Check_Direct_Boolean_Operator): If the boolean operation has been
	constant-folded, there is nothing to check.
	(Resolve_Comparison_Op, Resolve_Equality_Op, Resolve_Boolean_Op): Defer
	check on possible violation of restriction No_Direct_Boolean_Operators
	until after expansion of operands, to prevent spurious errors when
	operation is constant-folded.

	* sem_type.ads, sem_type.adb (Covers, Intersect_Types, Specific_Type,
	Has_Compatible_Type): Modified to give support to abstract interface
	types.
	(Interface_Present_In_Ancestor): New function to theck if some ancestor
	of a given type implements a given interface

	* sem_ch4.adb (Analyze_Call): Handle properly an indirect call whose
	prefix is a parameterless function that returns an access_to_procedure.
	(Transform_Object_Operation): Handle properly function calls of the
	form Obj.Op (X), which prior to analysis appear as indexed components.
	(Analyze_One_Call): Complete the error notification to help new Ada
	2005 users.
	(Analyze_Allocator): For an allocator without an initial value, where
	the designated type has a constrained partial view, a discriminant
	constraint is illegal.

From-SVN: r101024

1 files changed, 104 insertions, 34 deletions

diff --git a/gcc/ada/sem_ch12.adb b/gcc/ada/sem_ch12.adb
index 661ac76..fd4392a 100644
--- a/gcc/ada/sem_ch12.adb
+++ b/gcc/ada/sem_ch12.adb
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2005 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- --
@@ -690,12 +690,13 @@ package body Sem_Ch12 is
    --  parent at the end of the instantiation (see Remove_Parent).
 
    type Instance_Env is record
-      Ada_Version         : Ada_Version_Type;
-      Instantiated_Parent : Assoc;
-      Exchanged_Views     : Elist_Id;
-      Hidden_Entities     : Elist_Id;
-      Current_Sem_Unit    : Unit_Number_Type;
-      Parent_Unit_Visible : Boolean := False;
+      Ada_Version          : Ada_Version_Type;
+      Ada_Version_Explicit : Ada_Version_Type;
+      Instantiated_Parent  : Assoc;
+      Exchanged_Views      : Elist_Id;
+      Hidden_Entities      : Elist_Id;
+      Current_Sem_Unit     : Unit_Number_Type;
+      Parent_Unit_Visible  : Boolean := False;
    end record;
 
    package Instance_Envs is new Table.Table (
@@ -1696,6 +1697,8 @@ package body Sem_Ch12 is
          end if;
 
          Formal := New_Copy (Pack_Id);
+         Create_Instantiation_Source (N, Gen_Unit, False, S_Adjustment);
+
          New_N :=
            Copy_Generic_Node
              (Original_Node (Gen_Decl), Empty, Instantiating => True);
@@ -2620,17 +2623,30 @@ package body Sem_Ch12 is
             --  generic is not a child unit of another generic, to avoid scope
             --  problems and the reinstallation of parent instances.
 
-            if Front_End_Inlining
-              and then Expander_Active
+            if Expander_Active
               and then (not Is_Child_Unit (Gen_Unit)
                          or else not Is_Generic_Unit (Scope (Gen_Unit)))
-              and then (Is_In_Main_Unit (N)
-                          or else In_Main_Context (Current_Scope))
-              and then Nkind (Parent (N)) /= N_Compilation_Unit
               and then Might_Inline_Subp
               and then not Is_Actual_Pack
             then
-               Inline_Now := True;
+               if Front_End_Inlining
+                 and then (Is_In_Main_Unit (N)
+                            or else In_Main_Context (Current_Scope))
+                 and then Nkind (Parent (N)) /= N_Compilation_Unit
+               then
+                  Inline_Now := True;
+
+               --  In configurable_run_time mode we force the inlining of
+               --  predefined subprogram marked Inline_Always, to minimize
+               --  the use of the run-time library.
+
+               elsif Is_Predefined_File_Name
+                       (Unit_File_Name (Get_Source_Unit (Gen_Decl)))
+                 and then Configurable_Run_Time_Mode
+                 and then Nkind (Parent (N)) /= N_Compilation_Unit
+               then
+                  Inline_Now := True;
+               end if;
             end if;
 
             Needs_Body :=
@@ -2641,7 +2657,6 @@ package body Sem_Ch12 is
                            or else Might_Inline_Subp)
                 and then not Is_Actual_Pack
                 and then not Inline_Now
-
                 and then (Operating_Mode = Generate_Code
                             or else (Operating_Mode = Check_Semantics
                                       and then ASIS_Mode));
@@ -2657,12 +2672,11 @@ package body Sem_Ch12 is
             end if;
 
             --  If the current context is generic, and the package being
-            --  instantiated is declared within a formal package, there
-            --  is no body to instantiate until the enclosing generic is
-            --  instantiated, and there is an actual for the formal
-            --  package. If the formal package has parameters, we build a
-            --  regular package instance for it, that preceeds the original
-            --  formal package declaration.
+            --  instantiated is declared within a formal package, there is no
+            --  body to instantiate until the enclosing generic is instantiated
+            --  and there is an actual for the formal package. If the formal
+            --  package has parameters, we build regular package instance for
+            --  it, that preceeds the original formal package declaration.
 
             if In_Open_Scopes (Scope (Scope (Gen_Unit))) then
                declare
@@ -2683,9 +2697,9 @@ package body Sem_Ch12 is
             end if;
          end;
 
-         --  If we are generating the calling stubs from the instantiation
-         --  of a generic RCI package, we will not use the body of the
-         --  generic package.
+         --  If we are generating the calling stubs from the instantiation of
+         --  a generic RCI package, we will not use the body of the generic
+         --  package.
 
          if Distribution_Stub_Mode = Generate_Caller_Stub_Body
            and then Is_Compilation_Unit (Defining_Entity (N))
@@ -2829,7 +2843,8 @@ package body Sem_Ch12 is
                end if;
             end if;
 
-            --  There is a problem with inlining here.
+            --  There is a problem with inlining here
+            --  More comments needed??? what problem
 
             Set_Unit (Parent (N), Act_Decl);
             Set_Parent_Spec (Act_Decl, Parent_Spec (N));
@@ -3500,6 +3515,30 @@ package body Sem_Ch12 is
             Check_Elab_Instantiation (N);
          end if;
 
+         if Is_Dispatching_Operation (Act_Decl_Id)
+           and then Ada_Version >= Ada_05
+         then
+            declare
+               Formal : Entity_Id;
+
+            begin
+               Formal := First_Formal (Act_Decl_Id);
+               while Present (Formal) loop
+                  if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
+                    and then Is_Controlling_Formal (Formal)
+                    and then not Can_Never_Be_Null (Formal)
+                  then
+                     Error_Msg_NE ("access parameter& is controlling,",
+                       N, Formal);
+                     Error_Msg_NE ("\corresponding parameter of & must be"
+                       & " explicitly null-excluding", N, Gen_Id);
+                  end if;
+
+                  Next_Formal (Formal);
+               end loop;
+            end;
+         end if;
+
          Check_Hidden_Child_Unit (N, Gen_Unit, Act_Decl_Id);
 
          --  Subject to change, pending on if other pragmas are inherited ???
@@ -3507,7 +3546,6 @@ package body Sem_Ch12 is
          Validate_Categorization_Dependency (N, Act_Decl_Id);
 
          if not Is_Intrinsic_Subprogram (Act_Decl_Id) then
-
             if not Generic_Separately_Compiled (Gen_Unit) then
                Inherit_Context (Gen_Decl, N);
             end if;
@@ -3521,7 +3559,7 @@ package body Sem_Ch12 is
                   or else Is_Inlined (Act_Decl_Id))
               and then (Operating_Mode = Generate_Code
                           or else (Operating_Mode = Check_Semantics
-                                    and then ASIS_Mode))
+                                     and then ASIS_Mode))
               and then (Expander_Active or else ASIS_Mode)
               and then not ABE_Is_Certain (N)
               and then not Is_Eliminated (Act_Decl_Id)
@@ -3764,6 +3802,7 @@ package body Sem_Ch12 is
         (E1, E2 : Entity_Id) return Boolean
       is
          Ent : Entity_Id;
+
       begin
          Ent := E2;
          while Present (Ent) loop
@@ -5814,12 +5853,13 @@ package body Sem_Ch12 is
       Saved : Instance_Env;
 
    begin
-      Saved.Ada_Version         := Ada_Version;
-      Saved.Instantiated_Parent := Current_Instantiated_Parent;
-      Saved.Exchanged_Views     := Exchanged_Views;
-      Saved.Hidden_Entities     := Hidden_Entities;
-      Saved.Current_Sem_Unit    := Current_Sem_Unit;
-      Saved.Parent_Unit_Visible := Parent_Unit_Visible;
+      Saved.Ada_Version          := Ada_Version;
+      Saved.Ada_Version_Explicit := Ada_Version_Explicit;
+      Saved.Instantiated_Parent  := Current_Instantiated_Parent;
+      Saved.Exchanged_Views      := Exchanged_Views;
+      Saved.Hidden_Entities      := Hidden_Entities;
+      Saved.Current_Sem_Unit     := Current_Sem_Unit;
+      Saved.Parent_Unit_Visible  := Parent_Unit_Visible;
       Instance_Envs.Increment_Last;
       Instance_Envs.Table (Instance_Envs.Last) := Saved;
 
@@ -6976,6 +7016,22 @@ package body Sem_Ch12 is
             Nam := Make_Identifier (Loc, Chars (Formal_Sub));
          end if;
 
+      elsif Nkind (Specification (Formal)) = N_Procedure_Specification
+        and then Null_Present (Specification (Formal))
+      then
+         --  Generate null body for procedure, for use in the instance
+
+         Decl_Node :=
+           Make_Subprogram_Body (Loc,
+             Specification              => New_Spec,
+             Declarations               => New_List,
+             Handled_Statement_Sequence =>
+               Make_Handled_Sequence_Of_Statements (Loc,
+                 Statements => New_List (Make_Null_Statement (Loc))));
+
+         Set_Is_Intrinsic_Subprogram (Defining_Unit_Name (New_Spec));
+         return Decl_Node;
+
       else
          Error_Msg_Sloc := Sloc (Scope (Analyzed_S));
          Error_Msg_NE
@@ -8172,7 +8228,18 @@ package body Sem_Ch12 is
             Ancestor := Get_Instance_Of (Etype (Base_Type (A_Gen_T)));
          end if;
 
-         if not Is_Ancestor (Base_Type (Ancestor), Act_T) then
+         --  Ada 2005 (AI-251)
+
+         if Ada_Version >= Ada_05
+           and then Is_Interface (Ancestor)
+         then
+            if not Interface_Present_In_Ancestor (Act_T, Ancestor) then
+               Error_Msg_NE
+                 ("(Ada 2005) expected type implementing & in instantiation",
+                  Actual, Ancestor);
+            end if;
+
+         elsif not Is_Ancestor (Base_Type (Ancestor), Act_T) then
             Error_Msg_NE
               ("expect type derived from & in instantiation",
                Actual, First_Subtype (Ancestor));
@@ -9061,6 +9128,7 @@ package body Sem_Ch12 is
 
    begin
       Ada_Version := Saved.Ada_Version;
+      Ada_Version_Explicit := Saved.Ada_Version_Explicit;
 
       if No (Current_Instantiated_Parent.Act_Id) then
 
@@ -10060,16 +10128,18 @@ package body Sem_Ch12 is
      (Gen_Unit : Entity_Id;
       Act_Unit : Entity_Id)
    is
-
    begin
       --  Regardless of the current mode, predefined units are analyzed in
       --  the most current Ada mode, and earlier version Ada checks do not
       --  apply to predefined units.
 
+      --  Why is this not using the routine Opt.Set_Opt_Config_Switches ???
+
       if Is_Internal_File_Name
           (Fname => Unit_File_Name (Get_Source_Unit (Gen_Unit)),
            Renamings_Included => True) then
          Ada_Version := Ada_Version_Type'Last;
+         Ada_Version_Explicit := Ada_Version_Explicit_Config;
       end if;
 
       Current_Instantiated_Parent := (Gen_Unit, Act_Unit, Assoc_Null);