re PR debug/55063 (Thousands of failures in the libstdc++-v3 tests after revision 192739)

gcc/
	PR debug/55063
	* dwarf2out.c (prune_unused_types_prune): Check whether DIE is
	already a declaration.

From-SVN: r192820

gcc/ChangeLog

+2012-10-25  Cary Coutant  <ccoutant@google.com>
+
+	PR debug/55063
+	* dwarf2out.c (prune_unused_types_prune): Check whether DIE is
+	already a declaration.
+
 2012-10-25  Vladimir Makarov  <vmakarov@redhat.com>
 
 	* lra-assigns.c (assign_by_spills): Add non-reload pseudos

gcc/dwarf2out.c

@@ -21259,7 +21259,8 @@ prune_unused_types_prune (dw_die_ref die)
   /* If we pruned children, and this is a class, mark it as a 
      declaration to inform debuggers that this is not a complete
      class definition.  */
-  if (pruned && die->die_mark == 1 && class_scope_p (die))
+  if (pruned && die->die_mark == 1 && class_scope_p (die)
+      && ! is_declaration_die (die))
     add_AT_flag (die, DW_AT_declaration, 1);
 }