[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

llvm-svn: 304357

7 files changed, 50 insertions, 17 deletions

diff --git a/libcxx/include/experimental/algorithm b/libcxx/include/experimental/algorithm
index b32d7ca66bd..3801cae4f16 100644
--- a/libcxx/include/experimental/algorithm
+++ b/libcxx/include/experimental/algorithm
@@ -39,17 +39,18 @@ SampleIterator sample(PopulationIterator first, PopulationIterator last,
 #include <algorithm>
 #include <type_traits>
 
-#include <__undef_min_max>
-
 #include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
-_LIBCPP_BEGIN_NAMESPACE_LFTS
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
 
 
+_LIBCPP_BEGIN_NAMESPACE_LFTS
+
 template <class _ForwardIterator, class _Searcher>
 _LIBCPP_INLINE_VISIBILITY
 _ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
@@ -67,4 +68,6 @@ _SampleIterator sample(_PopulationIterator __first, _PopulationIterator __last,
 
 _LIBCPP_END_NAMESPACE_LFTS
 
+_LIBCPP_POP_MACROS
+
 #endif /* _LIBCPP_EXPERIMENTAL_ALGORITHM */
diff --git a/libcxx/include/experimental/dynarray b/libcxx/include/experimental/dynarray
index f96a0e5fed3..16193317ad2 100644
--- a/libcxx/include/experimental/dynarray
+++ b/libcxx/include/experimental/dynarray
@@ -107,6 +107,9 @@ public:
 #pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 namespace std { namespace experimental { inline namespace __array_extensions_v1 {
 
 template <class _Tp>
@@ -295,5 +298,7 @@ template <class _Tp, class _Alloc>
 struct _LIBCPP_TEMPLATE_VIS uses_allocator<std::experimental::dynarray<_Tp>, _Alloc> : true_type {};
 _LIBCPP_END_NAMESPACE_STD
 
+_LIBCPP_POP_MACROS
+
 #endif  // if _LIBCPP_STD_VER > 11 
 #endif  // _LIBCPP_DYNARRAY
diff --git a/libcxx/include/experimental/functional b/libcxx/include/experimental/functional
index 75fc8e99f35..a136cbb57c8 100644
--- a/libcxx/include/experimental/functional
+++ b/libcxx/include/experimental/functional
@@ -89,21 +89,22 @@ inline namespace fundamentals_v1 {
 
 #include <experimental/__config>
 #include <functional>
-
 #include <algorithm>
 #include <type_traits>
 #include <vector>
 #include <array>
 #include <unordered_map>
 
-#include <__undef_min_max>
-
 #include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+
 _LIBCPP_BEGIN_NAMESPACE_LFTS
 
 #if _LIBCPP_STD_VER > 11
@@ -456,4 +457,6 @@ make_boyer_moore_horspool_searcher( _RandomAccessIterator __f, _RandomAccessIter
 
 _LIBCPP_END_NAMESPACE_LFTS
 
+_LIBCPP_POP_MACROS
+
 #endif /* _LIBCPP_EXPERIMENTAL_FUNCTIONAL */
diff --git a/libcxx/include/experimental/memory_resource b/libcxx/include/experimental/memory_resource
index 743f9cbe639..d101f3e0811 100644
--- a/libcxx/include/experimental/memory_resource
+++ b/libcxx/include/experimental/memory_resource
@@ -82,6 +82,9 @@ namespace pmr {
 #pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 _LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
 
 // Round __s up to next multiple of __a.
@@ -419,4 +422,6 @@ using resource_adaptor = __resource_adaptor_imp<
 
 _LIBCPP_END_NAMESPACE_LFTS_PMR
 
+_LIBCPP_POP_MACROS
+
 #endif /* _LIBCPP_EXPERIMENTAL_MEMORY_RESOURCE */
diff --git a/libcxx/include/experimental/numeric b/libcxx/include/experimental/numeric
index 6488a68eca6..d784c08f0fe 100644
--- a/libcxx/include/experimental/numeric
+++ b/libcxx/include/experimental/numeric
@@ -41,6 +41,9 @@ inline namespace fundamentals_v2 {
 #pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 #if _LIBCPP_STD_VER > 11
 
 _LIBCPP_BEGIN_NAMESPACE_LFTS_V2
@@ -110,4 +113,7 @@ lcm(_Tp __m, _Up __n)
 _LIBCPP_END_NAMESPACE_LFTS_V2
 
 #endif /* _LIBCPP_STD_VER > 11 */
+
+_LIBCPP_POP_MACROS
+
 #endif /* _LIBCPP_EXPERIMENTAL_NUMERIC */
diff --git a/libcxx/include/experimental/optional b/libcxx/include/experimental/optional
index 48adfbae516..b251748fbf3 100644
--- a/libcxx/include/experimental/optional
+++ b/libcxx/include/experimental/optional
@@ -143,6 +143,21 @@ namespace std { namespace experimental { inline namespace fundamentals_v1 {
 #include <experimental/__config>
 #include <functional>
 #include <stdexcept>
+#if _LIBCPP_STD_VER > 11
+#include <initializer_list>
+#include <type_traits>
+#include <new>
+#include <__functional_base>
+#include <__debug>
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 
 _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
 class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_OPTIONAL_ACCESS bad_optional_access
@@ -160,17 +175,6 @@ _LIBCPP_END_NAMESPACE_EXPERIMENTAL
 
 #if _LIBCPP_STD_VER > 11
 
-#include <initializer_list>
-#include <type_traits>
-#include <new>
-#include <__functional_base>
-#include <__undef_min_max>
-#include <__debug>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#pragma GCC system_header
-#endif
-
 _LIBCPP_BEGIN_NAMESPACE_LFTS
 
 struct in_place_t {};
@@ -913,4 +917,6 @@ _LIBCPP_END_NAMESPACE_STD
 
 #endif  // _LIBCPP_STD_VER > 11
 
+_LIBCPP_POP_MACROS
+
 #endif  // _LIBCPP_EXPERIMENTAL_OPTIONAL
diff --git a/libcxx/include/experimental/string_view b/libcxx/include/experimental/string_view
index 41c0d34d3c8..da104f9a121 100644
--- a/libcxx/include/experimental/string_view
+++ b/libcxx/include/experimental/string_view
@@ -189,6 +189,9 @@ namespace std {
 #pragma GCC system_header
 #endif
 
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
 _LIBCPP_BEGIN_NAMESPACE_LFTS
 
     template<class _CharT, class _Traits = _VSTD::char_traits<_CharT> >
@@ -810,4 +813,6 @@ quoted ( std::experimental::basic_string_view <_CharT, _Traits> __sv,
 
 _LIBCPP_END_NAMESPACE_STD
 
+_LIBCPP_POP_MACROS
+
 #endif // _LIBCPP_LFTS_STRING_VIEW