Fix up the -Wc++XX-compat warnings to properly handle C++2a.

llvm-svn: 311750
diff --git a/clang/test/SemaCXX/cxx17-compat.cpp b/clang/test/SemaCXX/cxx17-compat.cpp
new file mode 100644
index 0000000..79c8507
--- /dev/null
+++ b/clang/test/SemaCXX/cxx17-compat.cpp
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -pedantic -verify %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++2a -Wc++17-compat-pedantic -verify %s
+
+struct A {};
+int (A::*pa)() const&;
+int use_pa = (A().*pa)();
+#if __cplusplus <= 201703L
+  // expected-warning@-2 {{invoking a pointer to a 'const &' member function on an rvalue is a C++2a extension}}
+#else
+  // expected-warning@-4 {{invoking a pointer to a 'const &' member function on an rvalue is incompatible with C++ standards before C++2a}}
+#endif
+
+struct B {
+  void b() {
+    (void) [=, this] {};
+#if __cplusplus <= 201703L
+    // expected-warning@-2 {{explicit capture of 'this' with a capture default of '=' is a C++2a extension}}
+#else
+    // expected-warning@-4 {{explicit capture of 'this' with a capture default of '=' is incompatible with C++ standards before C++2a}}
+#endif
+  }
+};