Use __is_identifier to detect Clang extensions instead of __has_extension.

When -pedantic-errors is specified `__has_extension(<feature>)` is always
false when it would otherwise be true. This causes C++03 <atomic> to break
along with other issues.

This patch avoids the above problem by using __is_identifier(...) instead since
it is not affected by -pedantic-errors. For example instead of checking for
__has_extension(c_atomics) we now check `!__is_identifier(_Atomic)`, which
is only true when _Atomic is not a keyword provided by the compiler.

This patch applies similar changes to the detection logic for __decltype and
__nullptr as well.

Note that it does not apply this change to the C++03
`static_assert` macro since -Wc11-extensions warnings generated by expanding
that macro will appear in user code, and will not be suppressed as part of a
system header.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291995 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/test/support/test_macros.h b/test/support/test_macros.h
index 40d366ab1..f1a0bdd1a 100644
--- a/test/support/test_macros.h
+++ b/test/support/test_macros.h
@@ -13,6 +13,11 @@
 
 #include <ciso646> // Get STL specific macros like _LIBCPP_VERSION
 
+#if defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvariadic-macros"
+#endif
+
 #define TEST_CONCAT1(X, Y) X##Y
 #define TEST_CONCAT(X, Y) TEST_CONCAT1(X, Y)
 
@@ -177,4 +182,9 @@ struct is_same<T, T> { enum {value = 1}; };
 #endif
 #endif
 
+
+#if defined(__GNUC__)
+#pragma GCC diagnostic pop
+#endif
+
 #endif // SUPPORT_TEST_MACROS_HPP