This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
[PR c++/81229] Dangling GC pointer
- From: Nathan Sidwell <nathan at acm dot org>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 30 Jun 2017 07:43:10 -0400
- Subject: [PR c++/81229] Dangling GC pointer
- Authentication-results: sourceware.org; auth=none
This fixes 81229, an ICE during GC. When converting the namespace
symbol handling I was mystified by a SET_IDENTIFIER_TYPE call that
seemingly had no effect. Turns out it is needed, because we've already
set the IDENTIFIER_TYPE to the new decl's type. Whose name points back
at the new TYPE_DECL. Which duplicate_decls gcc_freed when it found the
already matched one. So we need to change IDENTIFIER_TYPE to the old
decl's type node.
This problem didn't manifest on a non-attributed int typedef, not sure
why. I suspect I'll be coming back to revisit this code as my symbol
table overhaul continues.
nathan
--
Nathan Sidwell
2017-06-30 Nathan Sidwell <nathan@acm.org>
PR c++/81229
* name-lookup.c (do_pushdecl): Reset IDENTIFIER_TYPE when finding
a matching TYPE_DECL.
* g++.dg/lookup/pr81229.C: New.
Index: gcc/cp/name-lookup.c
===================================================================
--- gcc/cp/name-lookup.c (revision 249834)
+++ gcc/cp/name-lookup.c (working copy)
@@ -2354,9 +2354,13 @@ do_pushdecl (tree decl, bool is_friend)
; /* Ignore using decls here. */
else if (tree match = duplicate_decls (decl, *iter, is_friend))
{
- if (iter.hidden_p ()
- && match != error_mark_node
- && !DECL_HIDDEN_P (match))
+ if (match == error_mark_node)
+ ;
+ else if (TREE_CODE (match) == TYPE_DECL)
+ /* The IDENTIFIER will have the type referring to the
+ now-smashed TYPE_DECL, because ...? Reset it. */
+ SET_IDENTIFIER_TYPE_VALUE (name, TREE_TYPE (match));
+ else if (iter.hidden_p () && !DECL_HIDDEN_P (match))
{
/* Unhiding a previously hidden decl. */
tree head = iter.reveal_node (old);
Index: gcc/testsuite/g++.dg/lookup/pr81229.C
===================================================================
--- gcc/testsuite/g++.dg/lookup/pr81229.C (revision 0)
+++ gcc/testsuite/g++.dg/lookup/pr81229.C (working copy)
@@ -0,0 +1,7 @@
+// PR c++/81229 GC ICE with stale pointed in identifier type.
+// { dg-additional-options "--param ggc-min-heapsize=0" }
+
+typedef unsigned L;
+typedef unsigned L;
+
+L l;