c++: add fixed test [PR91079]

Fixed by r12-2975.

	PR c++/91079
	DR 1881

gcc/testsuite/ChangeLog:

	* g++.dg/ext/is_std_layout5.C: New test.

diff --git a/gcc/testsuite/g++.dg/ext/is_std_layout5.C b/gcc/testsuite/g++.dg/ext/is_std_layout5.C
new file mode 100644 (file)
index 0000000..875f3c0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_std_layout5.C
@@ -0,0 +1,13 @@
+// PR c++/91079
+// DR 1881 - Standard-layout classes and unnamed bit-fields
+// { dg-do compile { target c++11 } }
+
+struct A { int a : 4; };
+struct B : A { int b : 3; };
+static_assert(__is_standard_layout(A), "");
+static_assert(!__is_standard_layout(B), "");
+
+struct C { int : 0; };
+struct D : C { int : 0; };
+static_assert(__is_standard_layout(C), "");
+static_assert(!__is_standard_layout(D), "");