[Ada] Spurious visiblity error on private subtype and inlined constructs

[Arnaud Charlet <charlet at adacore dot com>]

This patch fixes a visibility error on a subtype of a derived private type,
when the enclosing unit is both the parent of an instantiated generic child
unit, and contains an expression function that is automatically  inlined.

The following must compile and execute quietly:

   gnatmake -q main
   main

with p2.child1;
procedure Main is
begin
   null;
end;
---
package P1 is
   type Ptr1_Type is private;
   Null_Ptr1 : constant Ptr1_Type;
private
   type Ptr1_Type is access Boolean;
   Null_Ptr1 : constant Ptr1_Type := null;
end;
---
with P1;

package P2 is

   pragma Elaborate_Body;

   type Ptr2 is private;
   Null_Ptr2 : constant Ptr2;

   function Is_Null (P : Ptr2) return Boolean is (P = Null_Ptr2);

   subtype Not_Null_Ptr2 is Ptr2
      with Dynamic_Predicate => not Is_Null (Not_Null_Ptr2);

private
   type Ptr2 is new P1.Ptr1_Type;
   Null_Ptr2 : constant Ptr2 := Ptr2 (P1.Null_Ptr1);
end;
---
package P2.Child1 is
   pragma Elaborate_Body;
end;
---
with P2.Gen1;
package body P2.Child1 is

   package Instance is new Gen1 (Boolean);

   procedure Foo is
   begin
      if Is_Null (Null_Ptr2) then
         raise Program_Error;
      end if;
      null;
   end;
   Thing : Ptr2 := Null_Ptr2;
begin
   Foo;
   raise Program_Error;
exception
   when Program_Error => null;
end;
---
package body P2.Gen1 is
   function Bar (P : Ptr2) return Boolean is
   begin
      return True;
   end;
end;
---
generic
   type Data_Type is limited private;
package P2.Gen1 is
   pragma Elaborate_Body;
end;
---
package body P2 is
   function Foo (P : Not_Null_Ptr2) return Ptr2 is
   begin
      return Null_Ptr2;
   end;
end;

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

2015-05-26  Ed Schonberg  <schonberg@adacore.com>

	* sem_ch7.adb (Install_Private_Declarations,
	Swap_Private_Dependents): Ensure that both views of the dependent
	subtype are immediately visible if we are within their scope. This
	may be needed when a procedure body is both the parent of an
	instantiated child unit, and is itself used to inline a local
	function.

Attachment: difs
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