1 files changed, 7 insertions, 3 deletions
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 637671bc1bc..00e0c063e86 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -4664,10 +4664,14 @@ convert_default_arg (tree type, tree arg, tree fn, int parmnum)
     }
   else
     {
-      /* This could get clobbered by the following call.  */
-      if (TREE_HAS_CONSTRUCTOR (arg))
+      /* We must make a copy of ARG, in case subsequent processing
+	 alters any part of it.  For example, during gimplification a
+	 cast of the form (T) &X::f (where "f" is a member function)
+	 will lead to replacing the PTRMEM_CST for &X::f with a
+	 VAR_DECL.  We can avoid the copy for constants, since they
+	 are never modified in place.  */
+      if (!CONSTANT_CLASS_P (arg))
 	arg = copy_node (arg);
-
       arg = convert_for_initialization (0, type, arg, LOOKUP_NORMAL,
 					"default argument", fn, parmnum);
       arg = convert_for_arg_passing (type, arg);