[pushed] c++: add fixed test [PR91079]

[Marek Polacek]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- >8 --
Fixed by r12-2975.

        PR c++/91079
        DR 1881

gcc/testsuite/ChangeLog:

        * g++.dg/ext/is_std_layout5.C: New test.
---
 gcc/testsuite/g++.dg/ext/is_std_layout5.C | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_std_layout5.C

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
index 00000000000..875f3c0948d
--- /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), "");

base-commit: e7d015b2506a1d9e84d9f7182e42e097147527e1
-- 
2.44.0