[Libc++] Use #pragma push_macro/pop_macro to better handle min/max on Windows Summary: This patch improves how libc++ handles min/max macros within the headers. Previously libc++ would undef them and emit a warning. This patch changes libc++ to use `#pragma push_macro` to save the macro before undefining it, and `#pragma pop_macro` to restore the macros and the end of the header. Reviewers: mclow.lists, bcraig, compnerd, EricWF Reviewed By: EricWF Subscribers: cfe-commits, krytarowski Differential Revision: https://reviews.llvm.org/D33080 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@304357 91177308-0d34-0410-b5e6-96231b3b80d8 
diff --git a/include/regex b/include/regex index 0f49b95..443c2e3 100644 --- a/include/regex +++ b/include/regex 
@@ -765,12 +765,14 @@  #include <vector>  #include <deque>   -#include <__undef_min_max> -  #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)  #pragma GCC system_header  #endif   +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + +  _LIBCPP_BEGIN_NAMESPACE_STD    namespace regex_constants @@ -6562,4 +6564,6 @@    _LIBCPP_END_NAMESPACE_STD   +_LIBCPP_POP_MACROS +  #endif // _LIBCPP_REGEX