c++: add fixed testcase [PR109997]

Fixed by r14-9713 for PR100667.

	PR c++/109997

gcc/testsuite/ChangeLog:

	* g++.dg/ext/is_assignable1.C: New test.

diff --git a/gcc/testsuite/g++.dg/ext/is_assignable1.C b/gcc/testsuite/g++.dg/ext/is_assignable1.C
new file mode 100644 (file)
index 0000000..31e6450
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_assignable1.C
@@ -0,0 +1,4 @@
+// PR c++/109997
+
+struct S;
+bool b = __is_assignable(int, S); // { dg-error "incomplete" }