re PR c++/55685 (ICE: canonical types differ for identical types)

	PR c++/55685
	* pt.c (tsubst_copy_and_build): Don't use SIZEOF_EXPR_TYPE_P in
	templates.

From-SVN: r194517

gcc/cp/ChangeLog

 2012-12-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/55685
+	* pt.c (tsubst_copy_and_build): Don't use SIZEOF_EXPR_TYPE_P in
+	templates.
+
 	PR c++/42315
 	* decl.c (maybe_deduce_size_from_array_init): Don't change the
 	variable type.

gcc/cp/pt.c

@@ -13563,7 +13563,7 @@ tsubst_copy_and_build (tree t,
 	  {
 	    if (TREE_CODE (r) != SIZEOF_EXPR || TYPE_P (op1))
 	      {
-		if (TYPE_P (op1))
+		if (!processing_template_decl && TYPE_P (op1))
 		  {
 		    r = build_min (SIZEOF_EXPR, size_type_node,
 				   build1 (NOP_EXPR, op1, error_mark_node));

gcc/testsuite/g++.dg/template/sizeof15.C

+// PR c++/55685
+
+typedef __SIZE_TYPE__ size_t;
+template <size_t T, size_t U>
+struct A;
+
+template <typename T> struct B
+{
+  static A <sizeof (T), 0> x;
+};
+
+template <typename T>
+A <sizeof (T), 0> B <T>::x;