[Bug ada/65524] New: gnatbind generates decrementing the unexisting elab-counter into finalize_library

["demoonlit at panathenaia dot halfmoon.jp" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65524

            Bug ID: 65524
           Summary: gnatbind generates decrementing the unexisting
                    elab-counter into finalize_library
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: demoonlit at panathenaia dot halfmoon.jp

I found some cases that gnatbind generates decrementing the unexisting
elaboration counter of each package Exxx.

   E142 : Short_Integer; pragma Import (Ada, E142, "system__exn_lli_E");
   ... some Exxx are declared ...

   procedure finalize_library is
   begin
      ...
      E132 := E132 - 1; -- * E132 is not declared in above *
      ...
   end finalize_library;

A cause is a package having _finalize_spec/_finalize_body without
_elabs/_elabb.
I still have not been able to make the minimal example, but have made a patch.

In bindgen.adb, Gen_Elab_Externals refers U.Set_Elab_Entity to generate Exxx.
However, Gen_Finalize_Library does not refer it.

--- a/gcc/ada/bindgen.adb
+++ b/gcc/ada/bindgen.adb
@@ -1434,7 +1434,9 @@ package body Bindgen is
             --  has a finalizer. In that case, this is where we decrement
             --  the elaboration entity.

-            if U.Utype = Is_Body and then Uspec.Has_Finalizer then
+            if U.Utype = Is_Body and then Uspec.Has_Finalizer
+               and then Uspec.Set_Elab_Entity
+            then
                if not Lib_Final_Built then
                   Gen_Header;
                   Lib_Final_Built := True;
@@ -1548,7 +1550,9 @@ package body Bindgen is

             WBI ("      begin");

-            if U.Utype /= Is_Spec then
+            if U.Utype /= Is_Spec
+               and then Uspec.Set_Elab_Entity
+            then
                Set_String ("         E");
                Set_Unit_Number (Unum);
                Set_String (" := E");