Fix internal error on extension with interface at -O2

This is a regression present on the mainline, 10 and 9 branches, in the
form of an internal error with the Ada compiler when a covariant-only
thunk is inlined into its caller.

gcc/ada/
	* gcc-interface/trans.c (make_covariant_thunk): Set the DECL_CONTEXT
	of the parameters and do not set TREE_PUBLIC on the thunk.
	(maybe_make_gnu_thunk): Pass the alias to the covariant thunk.
	* gcc-interface/utils.c (finish_subprog_decl): Set the DECL_CONTEXT
	of the parameters here...
	(begin_subprog_body): ...instead of here.

gcc/testsuite/
	* gnat.dg/thunk2.adb, gnat.dg/thunk2.ads: New test.
	* gnat.dg/thunk2_pkg.ads: New helper.

1 files changed, 14 insertions, 10 deletions

diff --git a/gcc/ada/gcc-interface/trans.c b/gcc/ada/gcc-interface/trans.c
index 6402c73..ae7a52f 100644
--- a/gcc/ada/gcc-interface/trans.c
+++ b/gcc/ada/gcc-interface/trans.c
@@ -10612,7 +10612,7 @@ make_alias_for_thunk (tree target)
   return alias;
 }
 
-/* Create the covariant part of the {GNAT,GNU}_THUNK.  */
+/* Create the local covariant part of {GNAT,GNU}_THUNK.  */
 
 static tree
 make_covariant_thunk (Entity_Id gnat_thunk, tree gnu_thunk)
@@ -10623,6 +10623,11 @@ make_covariant_thunk (Entity_Id gnat_thunk, tree gnu_thunk)
 		  gnu_name, TREE_TYPE (gnu_thunk));
 
   DECL_ARGUMENTS (gnu_cv_thunk) = copy_list (DECL_ARGUMENTS (gnu_thunk));
+  for (tree param_decl = DECL_ARGUMENTS (gnu_cv_thunk);
+       param_decl;
+       param_decl = DECL_CHAIN (param_decl))
+    DECL_CONTEXT (param_decl) = gnu_cv_thunk;
+
   DECL_RESULT (gnu_cv_thunk) = copy_node (DECL_RESULT (gnu_thunk));
   DECL_CONTEXT (DECL_RESULT (gnu_cv_thunk)) = gnu_cv_thunk;
 
@@ -10630,7 +10635,6 @@ make_covariant_thunk (Entity_Id gnat_thunk, tree gnu_thunk)
   DECL_CONTEXT (gnu_cv_thunk) = DECL_CONTEXT (gnu_thunk);
   TREE_READONLY (gnu_cv_thunk) = TREE_READONLY (gnu_thunk);
   TREE_THIS_VOLATILE (gnu_cv_thunk) = TREE_THIS_VOLATILE (gnu_thunk);
-  TREE_PUBLIC (gnu_cv_thunk) = TREE_PUBLIC (gnu_thunk);
   DECL_ARTIFICIAL (gnu_cv_thunk) = 1;
 
   return gnu_cv_thunk;
@@ -10760,6 +10764,12 @@ maybe_make_gnu_thunk (Entity_Id gnat_thunk, tree gnu_thunk)
 
   cgraph_node *target_node = cgraph_node::get_create (gnu_target);
 
+  /* We may also need to create an alias for the target in order to make
+     the call local, depending on the linkage of the target.  */
+  tree gnu_alias = use_alias_for_thunk_p (gnu_target)
+		  ? make_alias_for_thunk (gnu_target)
+		  : gnu_target;
+
   /* If the return type of the target is a controlling type, then we need
      both an usual this thunk and a covariant thunk in this order:
 
@@ -10772,17 +10782,11 @@ maybe_make_gnu_thunk (Entity_Id gnat_thunk, tree gnu_thunk)
       tree gnu_cv_thunk = make_covariant_thunk (gnat_thunk, gnu_thunk);
       target_node->create_thunk (gnu_cv_thunk, gnu_target, false,
 				 - fixed_offset, 0, 0,
-				 NULL_TREE, gnu_target);
+				 NULL_TREE, gnu_alias);
 
-      gnu_target = gnu_cv_thunk;
+      gnu_alias = gnu_target = gnu_cv_thunk;
     }
 
-  /* We may also need to create an alias for the target in order to make
-     the call local, depending on the linkage of the target.  */
-  tree gnu_alias = use_alias_for_thunk_p (gnu_target)
-		  ? make_alias_for_thunk (gnu_target)
-		  : gnu_target;
-
   target_node->create_thunk (gnu_thunk, gnu_target, true,
 			     fixed_offset, virtual_value, indirect_offset,
 			     virtual_offset, gnu_alias);