tree 210c6581def85a4b1d9caeaf3d6e661c5ca30bb7
parent d5904a27648ae30cd25d1a41d11b9be298198bb3
author Eric Fiselier <eric@efcs.ca> 1484368078 +0000
committer Eric Fiselier <eric@efcs.ca> 1484368078 +0000

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