re PR c++/54652 (ICE with -g)

	PR c++/54652
	* decl.c (duplicate_decls): Always use oldtype for TYPE_DECL.

From-SVN: r207169

gcc/cp/ChangeLog

 2014-01-27  Jason Merrill  <jason@redhat.com>
 
+	PR c++/54652
+	* decl.c (duplicate_decls): Always use oldtype for TYPE_DECL.
+
 	PR c++/58504
 	* pt.c (tsubst_copy_and_build) [TRAIT_EXPR]: Use tsubst for
 	types.

gcc/cp/decl.c

@@ -1926,9 +1926,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool newdecl_is_friend)
       /* Merge the data types specified in the two decls.  */
       newtype = merge_types (TREE_TYPE (newdecl), TREE_TYPE (olddecl));
 
-      /* If merge_types produces a non-typedef type, just use the old type.  */
-      if (TREE_CODE (newdecl) == TYPE_DECL
-	  && newtype == DECL_ORIGINAL_TYPE (newdecl))
+      /* For typedefs use the old type, as the new type's DECL_NAME points
+	 at newdecl, which will be ggc_freed.  */
+      if (TREE_CODE (newdecl) == TYPE_DECL)
 	newtype = oldtype;
 
       if (VAR_P (newdecl))

gcc/testsuite/g++.dg/ext/attrib48.C

+// PR c++/54652
+
+typedef unsigned L __attribute__ ((aligned));
+typedef unsigned L __attribute__ ((aligned));
+
+L l;