[clang][Interp][NFC] Add simple test case for atomic types

Author: tbaederr

clang/test/AST/Interp/atomic.cpp

@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify=both,expected -std=c++11 %s
+// RUN: %clang_cc1 -verify=both,ref -std=c++11 %s
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify=both,expected -std=c++98 %s
+// RUN: %clang_cc1 -verify=both,ref -std=c++98 %s
+
+
+
+// expected-no-diagnostics
+// ref-no-diagnostics
+
+
+/// Rejected in c++98
+#if __cplusplus >= 201103L
+constexpr _Atomic(bool) B = true;
+static_assert(B, "");
+#endif
+