--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp0x/alignas6.C	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,29 @@
+// PR c++/69089
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wno-attributes" }
+
+alignas (0) int valid1;
+alignas (1 - 1) int valid2;
+struct Tvalid
+{
+  alignas (0) int i;
+  alignas (2 * 0) int j;
+};
+
+alignas (-1) int invalid1; /* { dg-error "not a positive power of 2" } */
+alignas (1 - 2) int invalid2; /* { dg-error "not a positive power of 2" } */
+struct Tinvalid
+{
+  alignas (-1) int i; /* { dg-error "not a positive power of 2" } */
+  alignas (2 * 0 - 1) int j; /* { dg-error "not a positive power of 2" } */
+};
+
+template <int N> struct TNvalid1 { alignas (N) int i; };
+TNvalid1<0> SNvalid1;
+template <int N> struct TNvalid2 { alignas (N) int i; };
+TNvalid2<1 - 1> SNvalid2;
+
+template <int N> struct TNinvalid1 { alignas (N) int i; }; /* { dg-error "not a positive power of 2" } */
+TNinvalid1<-1> SNinvalid1;
+template <int N> struct TNinvalid2 { alignas (N) int i; }; /* { dg-error "not a positive power of 2" } */
+TNinvalid2<1 - 2> SNinvalid2;