diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 8a4082941d9..336c22e808c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2011-03-16  Jason Merrill  <jason@redhat.com>
+
+	PR c++/48115
+	* call.c (convert_arg_to_ellipsis): Handle incomplete type.
+
 2011-03-16  Jason Merrill  <jason@redhat.com>
 
 	* parser.c (cp_parser_abort_tentative_parse): Make sure we haven't
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 388f46cdf49..f75c2485e31 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -5671,6 +5671,10 @@ convert_arg_to_ellipsis (tree arg)
   arg_type = TREE_TYPE (arg);
 
   if (arg != error_mark_node
+      /* In a template (or ill-formed code), we can have an incomplete type
+	 even after require_complete_type, in which case we don't know
+	 whether it has trivial copy or not.  */
+      && COMPLETE_TYPE_P (arg_type)
       && (type_has_nontrivial_copy_init (arg_type)
 	  || TYPE_HAS_NONTRIVIAL_DESTRUCTOR (arg_type)))
     {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 72f30d8215a..ca82c7409c7 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2011-03-16  Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/template/incomplete6.C: New.
+
 2011-03-16  Jeff Law <law@redhat.com>
 
 	* gcc.dg/tree-ssa/vrp55.c: New test.
diff --git a/gcc/testsuite/g++.dg/template/incomplete6.C b/gcc/testsuite/g++.dg/template/incomplete6.C
new file mode 100644
index 00000000000..7138b6a3b41
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/incomplete6.C
@@ -0,0 +1,22 @@
+// PR c++/48115
+
+template<typename> struct templ { };
+
+template<typename T> T declval();
+
+typedef int (*F2)(...);
+
+template<int> struct Int { };
+
+template<typename F, typename T>
+struct S
+{
+    template<typename A>
+        Int<sizeof( declval<F>()(T()) )>
+        f(A);
+};
+
+int main()
+{
+    S<F2, templ<int> >().f(0);
+}