--- gcc/cp/tree.c.jj	2012-11-12 11:23:01.000000000 +0100
+++ gcc/cp/tree.c	2012-11-15 10:57:09.073103517 +0100
@@ -2610,10 +2610,13 @@ cp_tree_equal (tree t1, tree t2)
 	tree o1 = TREE_OPERAND (t1, 0);
 	tree o2 = TREE_OPERAND (t2, 0);
 
-	if (SIZEOF_EXPR_TYPE_P (t1))
-	  o1 = TREE_TYPE (o1);
-	if (SIZEOF_EXPR_TYPE_P (t2))
-	  o2 = TREE_TYPE (o2);
+	if (code1 == SIZEOF_EXPR)
+	  {
+	    if (SIZEOF_EXPR_TYPE_P (t1))
+	      o1 = TREE_TYPE (o1);
+	    if (SIZEOF_EXPR_TYPE_P (t2))
+	      o2 = TREE_TYPE (o2);
+	  }
 	if (TREE_CODE (o1) != TREE_CODE (o2))
 	  return false;
 	if (TYPE_P (o1))
--- gcc/testsuite/g++.dg/template/alignof2.C.jj	2012-11-15 11:00:36.126424342 +0100
+++ gcc/testsuite/g++.dg/template/alignof2.C	2012-11-15 11:00:55.144370137 +0100
@@ -0,0 +1,9 @@
+// PR c++/55337
+// { dg-do compile }
+
+template <int> struct A;
+template <typename T> struct B
+{
+  static A <__alignof__ (T)> b;
+};
+template <typename T> A<__alignof__ (T)> B<T>::b;