Define std::byte for C++17 (P0298R3)

	* doc/xml/manual/status_cxx2017.xml: Document std::byte support.
	* include/c_global/cstddef (std::byte): Define for C++17.
	* testsuite/18_support/byte/global_neg.cc: New test.
	* testsuite/18_support/byte/ops.cc: New test.
	* testsuite/18_support/byte/requirements.cc: New test.

From-SVN: r246005

1 files changed, 129 insertions, 0 deletions

diff --git a/libstdc++-v3/include/c_global/cstddef b/libstdc++-v3/include/c_global/cstddef
index a571e80c2f6..09754ee45da 100644
--- a/libstdc++-v3/include/c_global/cstddef
+++ b/libstdc++-v3/include/c_global/cstddef
@@ -57,4 +57,133 @@ namespace std
 }
 #endif
 
+#if __cplusplus > 201402L
+namespace std
+{
+  /// std::byte
+  enum class byte : unsigned char {};
+
+  template<typename _IntegerType> struct __byte_operand;
+  template<> struct __byte_operand<bool> { using __type = byte; };
+  template<> struct __byte_operand<char> { using __type = byte; };
+  template<> struct __byte_operand<signed char> { using __type = byte; };
+  template<> struct __byte_operand<unsigned char> { using __type = byte; };
+#ifdef _GLIBCXX_USE_WCHAR_T
+  template<> struct __byte_operand<wchar_t> { using __type = byte; };
+#endif
+  template<> struct __byte_operand<char16_t> { using __type = byte; };
+  template<> struct __byte_operand<char32_t> { using __type = byte; };
+  template<> struct __byte_operand<short> { using __type = byte; };
+  template<> struct __byte_operand<unsigned short> { using __type = byte; };
+  template<> struct __byte_operand<int> { using __type = byte; };
+  template<> struct __byte_operand<unsigned int> { using __type = byte; };
+  template<> struct __byte_operand<long> { using __type = byte; };
+  template<> struct __byte_operand<unsigned long> { using __type = byte; };
+  template<> struct __byte_operand<long long> { using __type = byte; };
+  template<> struct __byte_operand<unsigned long long> { using __type = byte; };
+#if defined(__GLIBCXX_TYPE_INT_N_0)
+  template<> struct __byte_operand<__GLIBCXX_TYPE_INT_N_0>
+  { using __type = byte; };
+  template<> struct __byte_operand<unsigned __GLIBCXX_TYPE_INT_N_0>
+  { using __type = byte; };
+#endif
+#if defined(__GLIBCXX_TYPE_INT_N_1)
+  template<> struct __byte_operand<__GLIBCXX_TYPE_INT_N_1>
+  { using __type = byte; };
+  template<> struct __byte_operand<unsigned __GLIBCXX_TYPE_INT_N_1>
+  { using __type = byte; };
+#endif
+#if defined(__GLIBCXX_TYPE_INT_N_2)
+  template<> struct __byte_operand<__GLIBCXX_TYPE_INT_N_2>
+  { using __type = byte; };
+  template<> struct __byte_operand<unsigned __GLIBCXX_TYPE_INT_N_2>
+  { using __type = byte; };
+#endif
+  template<typename _IntegerType>
+    struct __byte_operand<const _IntegerType>
+    : __byte_operand<_IntegerType> { };
+  template<typename _IntegerType>
+    struct __byte_operand<volatile _IntegerType>
+    : __byte_operand<_IntegerType> { };
+  template<typename _IntegerType>
+    struct __byte_operand<const volatile _IntegerType>
+    : __byte_operand<_IntegerType> { };
+
+  template<typename _IntegerType>
+    using __byte_op_t = typename __byte_operand<_IntegerType>::__type;
+
+  template<typename _IntegerType>
+    constexpr __byte_op_t<_IntegerType>&
+    operator<<=(byte& __b, _IntegerType __shift) noexcept
+    { return __b = byte(static_cast<unsigned char>(__b) << __shift); }
+
+  template<typename _IntegerType>
+    constexpr __byte_op_t<_IntegerType>
+    operator<<(byte __b, _IntegerType __shift) noexcept
+    { return byte(static_cast<unsigned char>(__b) << __shift); }
+
+  template<typename _IntegerType>
+    constexpr __byte_op_t<_IntegerType>&
+    operator>>=(byte& __b, _IntegerType __shift) noexcept
+    { return __b = byte(static_cast<unsigned char>(__b) >> __shift); }
+
+  template<typename _IntegerType>
+    constexpr __byte_op_t<_IntegerType>
+    operator>>(byte __b, _IntegerType __shift) noexcept
+    { return byte(static_cast<unsigned char>(__b) >> __shift); }
+
+  constexpr byte&
+  operator|=(byte& __l, byte __r) noexcept
+  {
+    return __l =
+      byte(static_cast<unsigned char>(__l) | static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte
+  operator|(byte __l, byte __r) noexcept
+  {
+    return
+      byte(static_cast<unsigned char>(__l) | static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte&
+  operator&=(byte& __l, byte __r) noexcept
+  {
+   return __l =
+     byte(static_cast<unsigned char>(__l) & static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte
+  operator&(byte __l, byte __r) noexcept
+  {
+    return
+      byte(static_cast<unsigned char>(__l) & static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte&
+  operator^=(byte& __l, byte __r) noexcept
+  {
+    return __l =
+      byte(static_cast<unsigned char>(__l) ^ static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte
+  operator^(byte __l, byte __r) noexcept
+  {
+    return
+      byte(static_cast<unsigned char>(__l) ^ static_cast<unsigned char>(__r));
+  }
+
+  constexpr byte
+  operator~(byte __b) noexcept
+  { return byte(~static_cast<unsigned char>(__b)); }
+
+  template<typename _IntegerType>
+    constexpr _IntegerType
+    to_integer(__byte_op_t<_IntegerType> __b) noexcept
+    { return _IntegerType(__b); }
+
+} // namespace std
+#endif
+
 #endif // _GLIBCXX_CSTDDEF