Introduce a new test macro TEST_HAS_C11_FEATURES which is set when the underlying C library has C11 features. In C++17, we use those features. <__config> defines a similar macro, _LIBCPP_HAS_C11_FEATURES, but we don't want to use that in the library-independent parts of the tests, so define the new one. Also add a libc++-specific test to make sure the two stay in sync.

2 files changed, 66 insertions, 10 deletions

diff --git a/libcxx/test/libcxx/language.support/has_c11_features.pass.cpp b/libcxx/test/libcxx/language.support/has_c11_features.pass.cpp
new file mode 100644
index 00000000000..cdccc00e21b
--- /dev/null
+++ b/libcxx/test/libcxx/language.support/has_c11_features.pass.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+//	We have two macros for checking whether or not the underlying C library
+//	 has C11 features:
+//		TEST_HAS_C11_FEATURES    - which is defined in "test_macros.h"
+//		_LIBCPP_HAS_C11_FEATURES - which is defined in <__config>
+//	They should always be the same
+
+#ifdef TEST_HAS_C11_FEATURES
+# ifndef _LIBCPP_HAS_C11_FEATURES
+#  error "TEST_HAS_C11_FEATURES is defined, but _LIBCPP_HAS_C11_FEATURES is not"
+# endif
+#endif
+
+#ifdef _LIBCPP_HAS_C11_FEATURES
+# ifndef TEST_HAS_C11_FEATURES
+#  error "_LIBCPP_HAS_C11_FEATURES is defined, but TEST_HAS_C11_FEATURES is not"
+# endif
+#endif
+
+int main() {}
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
index dbbfd53094e..ac6ec79b923 100644
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -94,16 +94,6 @@
 #define TEST_GLIBC_PREREQ(major, minor) __GLIBC_PREREQ(major, minor)
 #endif
 
-/* Features that were introduced in C++14 */
-#if TEST_STD_VER >= 14
-#define TEST_HAS_EXTENDED_CONSTEXPR
-#define TEST_HAS_VARIABLE_TEMPLATES
-#endif
-
-/* Features that were introduced after C++14 */
-#if TEST_STD_VER > 14
-#endif
-
 #if TEST_STD_VER >= 11
 #define TEST_ALIGNOF(...) alignof(__VA_ARGS__)
 #define TEST_ALIGNAS(...) alignas(__VA_ARGS__)
@@ -132,6 +122,43 @@
 #define TEST_THROW_SPEC(...) throw(__VA_ARGS__)
 #endif
 
+// Sniff out to see if the underling C library has C11 features
+// Note that at this time (July 2018), MacOS X and iOS do NOT.
+#if __ISO_C_VISIBLE >= 2011
+#  if defined(__FreeBSD__)
+#    define TEST_HAS_C11_FEATURES
+#  elif defined(__Fuchsia__)
+#    define TEST_HAS_C11_FEATURES
+#  elif defined(__linux__)
+#    if !defined(_LIBCPP_HAS_MUSL_LIBC)
+#      if _LIBCPP_GLIBC_PREREQ(2, 17)
+#        define TEST_HAS_C11_FEATURES
+#      endif
+#    else // defined(_LIBCPP_HAS_MUSL_LIBC)
+#      define TEST_HAS_C11_FEATURES
+#    endif
+#  elif defined(_WIN32)
+#    if defined(_MSC_VER) && !defined(__MINGW32__)
+#      define TEST_HAS_C11_FEATURES // Using Microsoft's C Runtime library
+#    endif
+#  endif
+#endif
+
+/* Features that were introduced in C++14 */
+#if TEST_STD_VER >= 14
+#define TEST_HAS_EXTENDED_CONSTEXPR
+#define TEST_HAS_VARIABLE_TEMPLATES
+#endif
+
+/* Features that were introduced in C++17 */
+#if TEST_STD_VER >= 17
+#endif
+
+/* Features that were introduced after C++17 */
+#if TEST_STD_VER > 17
+#endif
+
+
 #define TEST_ALIGNAS_TYPE(...) TEST_ALIGNAS(TEST_ALIGNOF(__VA_ARGS__))
 
 #if !TEST_HAS_FEATURE(cxx_rtti) && !defined(__cpp_rtti) \