PLEASE APPROVE: patch to fix PR 5879, a serious gcc 3.1 regression

[Adam Megacz <patches at lists dot megacz dot com>]

Could somebody *please* approve this?

  - a

         - - - - - - - -   repost   - - - - - - - - -

This patch backs out a change made in December which causes a
regression. Please see the PR and
http://gcc.gnu.org/ml/java/2002-03/msg00072.html for more detail.

If there are no objections, I would like to apply it to the branch and
trunk.

  - a


Index: semantics.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/semantics.c,v
retrieving revision 1.252
diff -u -r1.252 semantics.c
--- semantics.c	2002/02/22 17:42:19	1.252
+++ semantics.c	2002/03/06 20:01:37
@@ -2550,6 +2550,7 @@
 genrtl_finish_function (fn)
      tree fn;
 {
+  tree no_return_label = NULL_TREE;
   tree t;
 
 #if 0
@@ -2578,10 +2579,59 @@
   /* Clean house because we will need to reorder insns here.  */
   do_pending_stack_adjust ();
 
-  /* If we have a named return value, we need to force a return so that
-     the return register is USEd.  */
-  if (DECL_NAME (DECL_RESULT (fn)))
+  if (!dtor_label && !DECL_CONSTRUCTOR_P (fn)
+      && return_label != NULL_RTX
+      && ! DECL_NAME (DECL_RESULT (current_function_decl)))
+    no_return_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
+
+  /* If this function is supposed to return a value, ensure that
+     we do not fall into the cleanups by mistake.  The end of our
+     function will look like this:
+
+     user code (may have return stmt somewhere)
+     goto no_return_label
+     cleanup_label:
+     cleanups
+     goto return_label
+     no_return_label:
+     NOTE_INSN_FUNCTION_END
+     return_label:
+     things for return
+
+     If the user omits a return stmt in the USER CODE section, we
+     will have a control path which reaches NOTE_INSN_FUNCTION_END.
+     Otherwise, we won't.  */
+  if (no_return_label)
+    {
+      DECL_CONTEXT (no_return_label) = fn;
+      DECL_INITIAL (no_return_label) = error_mark_node;
+      DECL_SOURCE_FILE (no_return_label) = input_filename;
+      DECL_SOURCE_LINE (no_return_label) = lineno;
+      expand_goto (no_return_label);
+    }
+
+  if (cleanup_label)
+    {
+      /* Remove the binding contour which is used to catch
+	 cleanup-generated temporaries.  */
+      expand_end_bindings (0, 0, 0);
+      poplevel (0, 0, 0);
+
+      /* Emit label at beginning of cleanup code for parameters.  */
+      emit_label (cleanup_label);
+    }
+
+  /* Finish building code that will trigger warnings if users forget
+     to make their functions return values.  */
+  if (return_label)
     emit_jump (return_label);
+  if (no_return_label)
+    {
+      /* We don't need to call `expand_*_return' here because we don't
+	 need any cleanups here--this path of code is only for error
+	 checking purposes.  */
+      expand_label (no_return_label);
+    }
 
   /* We hard-wired immediate_size_expand to zero in start_function.
      Expand_function_end will decrement this variable.  So, we set the