[Ada] Missing support for overriding indicators on protected subprograms

[Arnaud Charlet <charlet at adacore dot com>]

The compiler was prohibiting overriding indicators on the bodies of protected
subprograms. The parser was corrected to allow these. There were also problems
fixed in the semantic checking for use of "not overriding", which was requiring
subprograms to be primitive, whereas this form of overrriding indicator is
also allowed on protected subprograms (which are not defined to be primitive
operations). Additionally, when the style check -gnatyO was enabled, the
compiler failed to warn about the missing overriding indicator on declarations
of protected subprograms that implement an inherited operation, and this is
also corrected.

The test included below must produce the following error output when
compiled with:

  gcc -c -gnat05 -gnatyO protected_overriding.adb

protected_overriding.ads:15:07:
 (style) missing "overriding" indicator in declaration of "Proc_2"
protected_overriding.ads:17:22:
 subprogram "Proc_3" overrides inherited operation at line 9


package Protected_Overriding is

   type I is limited interface;

   procedure Proc_1 (V : in out I) is abstract;

   procedure Proc_2 (V : in out I) is abstract;

   procedure Proc_3 (V : in out I) is abstract;

   protected PT is new I with

      overriding procedure Proc_1;      -- OK

      procedure Proc_2;                 -- ERROR (missing overriding)

      not overriding procedure Proc_3;  -- ERROR (must be overriding)

      not overriding procedure Extra;   -- OK

      not overriding function "not" (I : Integer) return Boolean; -- OK

   end PT;

end Protected_Overriding;

package body Protected_Overriding is

   protected body PT is

      overriding
      procedure Proc_1 is
      begin
         null;
      end Proc_1;

      overriding
      procedure Proc_2 is
      begin
         null;
      end Proc_2;

      procedure Proc_3 is
      begin
         null;
      end Proc_3;

      not overriding
      procedure Extra is
      begin
         null;
      end Extra;

      not overriding
      function "not" (I : Integer) return Boolean is
      begin
         return False;
      end "not";

   end PT;

end Protected_Overriding;

Tested on x86_64-pc-linux-gnu, committed on trunk

2009-04-17  Gary Dismukes  <dismukes@adacore.com>

	* par-ch6.adb (P_Subprogram): Overriding indicators should be allowed
	on protected subprogram bodies, so exclude the case where Pf_Flags is
	Pf_Decl_Pbod from the error check.

	* par-ch9.adb (P_Protected_Operation_Items): Permit overriding
	indicators on subprograms in protected bodies, and proceed with parsing
	the subprogram.

	* sem_ch6.adb (Verify_Overriding_Indicator): Exclude protected
	subprograms from the check for primitiveness on subprograms with
	overriding indicators.
	(Check_Overriding_Indicator): Include protected subprograms in the
	style check for missing overriding indicators.

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