--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/Sema/128bitfloat.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -verify -std=gnu++11 %s
+// RUN: %clang_cc1 -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple powerpc64-linux -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple i686-windows-gnu -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-windows-gnu -verify -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-windows-msvc -verify -std=c++11 %s
+
+#if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
+__float128 f;
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<__float128> {};
+int g(int x, __float128 *y) {
+  return x + *y;
+}
+
+// expected-no-diagnostics
+#else
+#if !defined(__STRICT_ANSI__)
+__float128 f;  // expected-error {{__float128 is not supported on this target}}
+// But this should work:
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<__float128> {};  // expected-error {{__float128 is not supported on this target}}
+
+// FIXME: This could have a better diag.
+int g(int x, __float128 *y) {  // expected-error {{__float128 is not supported on this target}}
+  return x + *y;
+}
+
+#else
+__float128 f;  // expected-error {{__float128 is not supported on this target}}
+template<typename> struct __is_floating_point_helper {};
+template<> struct __is_floating_point_helper<__float128> {};  // expected-error {{__float128 is not supported on this target}}
+
+int g(int x, __float128 *y) {  // expected-error {{__float128 is not supported on this target}}
+  return x + *y;
+}
+
+#endif
+#endif