Implement P0298R3: 'std::byte'. Reviewed as https://reviews.llvm.org/D31022

llvm-svn: 298689

1 files changed, 29 insertions, 0 deletions

diff --git a/libcxx/include/cstddef b/libcxx/include/cstddef
index 103898b7d8b..62584494d97 100644
--- a/libcxx/include/cstddef
+++ b/libcxx/include/cstddef
@@ -28,6 +28,7 @@ Types:
     size_t
     max_align_t
     nullptr_t
+    byte // C++17
 
 }  // std
 
@@ -58,4 +59,32 @@ typedef long double max_align_t;
 
 _LIBCPP_END_NAMESPACE_STD
 
+#if _LIBCPP_STD_VER > 14
+namespace std  // purposefully not versioned
+{
+enum class byte : unsigned char {};
+
+constexpr byte& operator|=(byte& __lhs, byte __rhs) noexcept
+{ return __lhs = byte(static_cast<unsigned char>(__lhs) | static_cast<unsigned char>(__rhs)); }
+constexpr byte  operator| (byte  __lhs, byte __rhs) noexcept
+{ return         byte(static_cast<unsigned char>(__lhs) | static_cast<unsigned char>(__rhs)); }
+
+constexpr byte& operator&=(byte& __lhs, byte __rhs) noexcept
+{ return __lhs = byte(static_cast<unsigned char>(__lhs) & static_cast<unsigned char>(__rhs)); }
+constexpr byte  operator& (byte  __lhs, byte __rhs) noexcept
+{ return         byte(static_cast<unsigned char>(__lhs) & static_cast<unsigned char>(__rhs)); }
+
+constexpr byte& operator^=(byte& __lhs, byte __rhs) noexcept 
+{ return __lhs = byte(static_cast<unsigned char>(__lhs) ^ static_cast<unsigned char>(__rhs)); }
+constexpr byte  operator^ (byte  __lhs, byte __rhs) noexcept
+{ return         byte(static_cast<unsigned char>(__lhs) ^ static_cast<unsigned char>(__rhs)); }
+
+constexpr byte  operator~ (byte __b) noexcept
+{ return  byte(~static_cast<unsigned char>(__b)); }
+
+}
+
+#include <type_traits>  // rest of byte
+#endif
+
 #endif  // _LIBCPP_CSTDDEF