[Bug c++/49519] [4.7 Regression] Revision 175272 miscompiled 447.dealII in SPEC CPU 2006

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49519

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2011-06-24 04:41:09 UTC ---
Revert this patch:

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 4d2caa8..2716f78 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -10246,7 +10246,7 @@ tsubst_arg_types (tree arg_types,

    /* Do array-to-pointer, function-to-pointer conversion, and ignore
       top-level qualifiers as required.  */
-    type = TYPE_MAIN_VARIANT (type_decays_to (type));
+    type = cv_unqualified (type_decays_to (type));

    /* We do not substitute into default arguments here.  The standard
       mandates that they be instantiated only when needed, which is

fixes the crash.