[Ada] Fix internal error on function returning dynamically-sized type

[Eric Botcazou]

This is PR ada/109881, a tree sharing issue for the internal return type 
synthesized for a function returning a dynamically-sized type and taking an 
Out or In/Out parameter passed by copy.

Tested on x86-64/Linux, applied on mainline, 13 and 12 branches.


2023-11-16  Eric Botcazou  <ebotca...@adacore.com>

        PR ada/109881
        * gcc-interface/decl.cc (gnat_to_gnu_subprog_type): Also create a
        TYPE_DECL for the return type built for the CI/CO mechanism.


2023-11-16  Eric Botcazou  <ebotca...@adacore.com>

        * gnat.dg/varsize4.ads, gnat.dg/varsize4.adb: New test.
        * gnat.dg/varsize4_pkg.ads: New helper.

-- 
Eric Botcazou
diff --git a/gcc/ada/gcc-interface/decl.cc b/gcc/ada/gcc-interface/decl.cc
index 95fa508c559..9c7f6840e21 100644
--- a/gcc/ada/gcc-interface/decl.cc
+++ b/gcc/ada/gcc-interface/decl.cc
@@ -6329,6 +6329,12 @@ gnat_to_gnu_subprog_type (Entity_Id gnat_subprog, bool definition,
 
 	  if (debug_info_p)
 	    rest_of_record_type_compilation (gnu_cico_return_type);
+
+	  /* Declare it now since it will never be declared otherwise.  This
+	     is necessary to ensure that its subtrees are properly marked.  */
+	  create_type_decl (TYPE_NAME (gnu_cico_return_type),
+			    gnu_cico_return_type,
+			    true, debug_info_p, gnat_subprog);
 	}
 
       gnu_return_type = gnu_cico_return_type;

-- { dg-do compile }

package body Varsize4 is

   function Func (bytes_read : out Natural) return Arr is
      Ret : Arr := (others => False);
   begin
      return Ret;
   end;

   function Get return Natural is
      Data  : Arr;
      Bytes : Natural;
   begin
      Data := Func (Bytes);
      return Bytes;
   end;

end Varsize4;

with Varsize4_Pkg;

package Varsize4 is

   type Arr is array (1 .. Varsize4_Pkg.F) of Boolean;

   function Get return Natural;

end Varsize4;

package Varsize4_Pkg is

   function F return Natural;

end Varsize4_Pkg;