vector garbaged collected while still in use

[Xinliang David Li]

I have seen compiler build error (segmentation fault) in libstdc++-v3.
It turns out that a vector allocated in gc memory is GCed before the
vector is released. The gc call is from a call to synethesize_method
from cp_finish_decl.

The following patch fixes the problem. Compiler bootstraps and tested
on linux/x86-64. Ok for trunk (or better fix suggested)?

thanks,

David

2011-11-05  Xinliang David Li  <davi...@google.com>

        * cp/decl.c (cp_finish_decl): Prevent cleanups from
        being garbage collected before being released.


Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 181013)
+++ cp/decl.c   (working copy)
@@ -5902,6 +5902,8 @@ value_dependent_init_p (tree init)
    FLAGS is LOOKUP_ONLYCONVERTING if the = init syntax was used, else 0
    if the (init) syntax was used.  */

+static GTY (()) VEC(tree,gc) *cleanups_vec;
+
 void
 cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
                tree asmspec_tree, int flags)
@@ -5914,6 +5916,7 @@ cp_finish_decl (tree decl, tree init, bo
   bool var_definition_p = false;
   tree auto_node;

+  cleanups_vec = cleanups;
   if (decl == error_mark_node)
     return;
   else if (! decl)
@@ -6319,6 +6322,7 @@ cp_finish_decl (tree decl, tree init, bo
   FOR_EACH_VEC_ELT (tree, cleanups, i, t)
     push_cleanup (decl, t, false);
   release_tree_vector (cleanups);
+  cleanups_vec = NULL;

   if (was_readonly)
     TREE_READONLY (decl) = 1;