re PR c++/21123 (ICE in cp_expr_size, at cp/cp-objcp-common.c:101)

        PR c++/21123
        * cp-gimplify.c (cp_genericize_r): Don't dereference invisible reference
        parms in a thunk.

From-SVN: r107738

gcc/cp/ChangeLog

+2005-11-30  Jason Merrill  <jason@redhat.com>
+
+	PR c++/21123
+	* cp-gimplify.c (cp_genericize_r): Don't dereference invisible reference 
+	parms in a thunk.
+
 2005-11-30  Ben Elliston  <bje@au.ibm.com>
 
 	* typeck.c (build_x_unary_op): Correct spelling in error message.

gcc/cp/cp-gimplify.c

@@ -596,7 +596,10 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
   tree stmt = *stmt_p;
   struct pointer_set_t *p_set = (struct pointer_set_t*) data;
 
-  if (is_invisiref_parm (stmt))
+  if (is_invisiref_parm (stmt)
+      /* Don't dereference parms in a thunk, pass the references through. */
+      && !(DECL_THUNK_P (current_function_decl)
+           && TREE_CODE (stmt) == PARM_DECL))
     {
       *stmt_p = convert_from_reference (stmt);
       *walk_subtrees = 0;

gcc/testsuite/g++.dg/inherit/thunk5.C

+// PR c++/21123
+
+struct A
+{
+  A(const A &a);
+  const A& operator=(const A& a);
+};
+
+struct B
+{
+  virtual A f(A);
+};
+
+struct C : virtual B
+{
+  virtual A f(A);
+};
+
+A C::f(A a) 
+{
+  return a;
+}