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

…D31022

llvm-svn: 298689

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

libcxx/include/type_traits

@@ -4714,4 +4714,35 @@ struct __can_extract_map_key<_ValTy, _Key, _Key, _RawValTy>
 
 _LIBCPP_END_NAMESPACE_STD
 
+#if _LIBCPP_STD_VER > 14
+// std::byte
+namespace std  // purposefully not versioned
+{
+template <class _Integer>
+  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type &
+  operator<<=(byte& __lhs, _Integer __shift) noexcept
+  { return __lhs = byte(static_cast<unsigned char>(__lhs) << __shift); }
+
+template <class _Integer>
+  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type
+  operator<< (byte  __lhs, _Integer __shift) noexcept
+  { return         byte(static_cast<unsigned char>(__lhs) << __shift); }
+
+template <class _Integer>
+  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type &
+  operator>>=(byte& __lhs, _Integer __shift) noexcept
+  { return __lhs = byte(static_cast<unsigned char>(__lhs) >> __shift); }
+
+template <class _Integer>
+  constexpr typename enable_if<is_integral_v<_Integer>, byte>::type
+  operator>> (byte  __lhs, _Integer __shift) noexcept
+  { return         byte(static_cast<unsigned char>(__lhs) >> __shift); }
+
+template <class _Integer>
+  constexpr typename enable_if<is_integral_v<_Integer>, _Integer>::type
+  to_integer(byte __b) noexcept { return _Integer(__b); }
+
+}
+#endif
+
 #endif  // _LIBCPP_TYPE_TRAITS

libcxx/test/std/language.support/support.types/byte.pass.cpp

@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <type_traits>
+#include <test_macros.h>
+
+// XFAIL: c++98, c++03, c++11, c++14
+
+// std::byte is not an integer type, nor a character type. 
+// It is a distinct type for accessing the bits that ultimately make up object storage.
+
+static_assert( std::is_pod<std::byte>::value, "" );
+static_assert(!std::is_arithmetic<std::byte>::value, "" );
+static_assert(!std::is_integral<std::byte>::value, "" );
+
+static_assert(!std::is_same<std::byte,          char>::value, "" );
+static_assert(!std::is_same<std::byte,   signed char>::value, "" );
+static_assert(!std::is_same<std::byte, unsigned char>::value, "" );
+
+// The standard doesn't outright say this, but it's pretty clear that it has to be true.
+static_assert(sizeof(std::byte) == 1, "" );
+
+int main () {}

libcxx/test/std/language.support/support.types/byteops/and.assign.pass.cpp

@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// constexpr byte& operator &=(byte l, byte r) noexcept;
+
+
+constexpr std::byte test(std::byte b1, std::byte b2) {
+	std::byte bret = b1;
+	return bret &= b2;
+	}
+
+
+int main () {
+	std::byte b;  // not constexpr, just used in noexcept check
+	constexpr std::byte b1{1};
+	constexpr std::byte b8{8};
+	constexpr std::byte b9{9};
+
+	static_assert(noexcept(b &= b), "" );
+
+	static_assert(std::to_integer<int>(test(b1, b8)) == 0, "");
+	static_assert(std::to_integer<int>(test(b1, b9)) == 1, "");
+	static_assert(std::to_integer<int>(test(b8, b9)) == 8, "");
+
+	static_assert(std::to_integer<int>(test(b8, b1)) == 0, "");
+	static_assert(std::to_integer<int>(test(b9, b1)) == 1, "");
+	static_assert(std::to_integer<int>(test(b9, b8)) == 8, "");
+}

libcxx/test/std/language.support/support.types/byteops/and.pass.cpp

@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// constexpr byte operator&(byte l, byte r) noexcept;
+
+int main () {
+	constexpr std::byte b1{1};
+	constexpr std::byte b8{8};
+	constexpr std::byte b9{9};
+
+	static_assert(noexcept(b1 & b8), "" );
+
+	static_assert(std::to_integer<int>(b1 & b8) ==  0, "");
+	static_assert(std::to_integer<int>(b1 & b9) ==  1, "");
+	static_assert(std::to_integer<int>(b8 & b9) ==  8, "");
+
+	static_assert(std::to_integer<int>(b8 & b1) ==  0, "");
+	static_assert(std::to_integer<int>(b9 & b1) ==  1, "");
+	static_assert(std::to_integer<int>(b9 & b8) ==  8, "");
+}

libcxx/test/std/language.support/support.types/byteops/lshift.assign.fail.cpp

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class IntegerType>
+//   constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept;
+// This function shall not participate in overload resolution unless 
+//   is_integral_v<IntegerType> is true.
+
+
+constexpr std::byte test(std::byte b) {
+	return b <<= 2.0;
+	}
+
+
+int main () {
+	constexpr std::byte b1 = test(std::byte{1});
+}

libcxx/test/std/language.support/support.types/byteops/lshift.assign.pass.cpp

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class IntegerType>
+//   constexpr byte& operator<<=(byte& b, IntegerType shift) noexcept;
+// This function shall not participate in overload resolution unless 
+//   is_integral_v<IntegerType> is true.
+
+
+constexpr std::byte test(std::byte b) {
+	return b <<= 2;
+	}
+
+
+int main () {
+	std::byte b;  // not constexpr, just used in noexcept check
+	constexpr std::byte b2{2};
+	constexpr std::byte b3{3};
+
+	static_assert(noexcept(b <<= 2), "" );
+
+	static_assert(std::to_integer<int>(test(b2)) ==  8, "" );
+	static_assert(std::to_integer<int>(test(b3)) == 12, "" );
+
+}

libcxx/test/std/language.support/support.types/byteops/lshift.fail.cpp

@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class IntegerType>
+//    constexpr byte operator <<(byte b, IntegerType shift) noexcept;
+// These functions shall not participate in overload resolution unless 
+//   is_integral_v<IntegerType> is true.
+
+int main () {
+	constexpr std::byte b1{1};
+	constexpr std::byte b2 = b1 << 2.0f;
+}

libcxx/test/std/language.support/support.types/byteops/lshift.pass.cpp

@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template <class IntegerType>
+//    constexpr byte operator <<(byte b, IntegerType shift) noexcept;
+// These functions shall not participate in overload resolution unless 
+//   is_integral_v<IntegerType> is true.
+
+int main () {
+	constexpr std::byte b1{1};
+	constexpr std::byte b3{3};
+
+	static_assert(noexcept(b3 << 2), "" );
+
+	static_assert(std::to_integer<int>(b1 << 1) ==   2, "");
+	static_assert(std::to_integer<int>(b1 << 2) ==   4, "");
+	static_assert(std::to_integer<int>(b3 << 4) ==  48, "");
+	static_assert(std::to_integer<int>(b3 << 6) == 192, "");	
+}

libcxx/test/std/language.support/support.types/byteops/not.pass.cpp

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// constexpr byte operator~(byte b) noexcept;
+
+int main () {
+	constexpr std::byte b1{1};
+	constexpr std::byte b2{2};
+	constexpr std::byte b8{8};
+
+	static_assert(noexcept(~b1), "" );
+
+	static_assert(std::to_integer<int>(~b1) == 254, "");
+	static_assert(std::to_integer<int>(~b2) == 253, "");
+	static_assert(std::to_integer<int>(~b8) == 247, "");
+}

libcxx/test/std/language.support/support.types/byteops/or.assign.pass.cpp

@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstddef>
+#include <test_macros.h>
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// constexpr byte& operator |=(byte l, byte r) noexcept;
+
+
+constexpr std::byte test(std::byte b1, std::byte b2) {
+	std::byte bret = b1;
+	return bret |= b2;
+	}
+
+
+int main () {
+	std::byte b;  // not constexpr, just used in noexcept check
+	constexpr std::byte b1{1};
+	constexpr std::byte b2{2};
+	constexpr std::byte b8{8};
+
+	static_assert(noexcept(b |= b), "" );
+
+	static_assert(std::to_integer<int>(test(b1, b2)) ==  3, "");
+	static_assert(std::to_integer<int>(test(b1, b8)) ==  9, "");
+	static_assert(std::to_integer<int>(test(b2, b8)) == 10, "");
+
+	static_assert(std::to_integer<int>(test(b2, b1)) ==  3, "");
+	static_assert(std::to_integer<int>(test(b8, b1)) ==  9, "");
+	static_assert(std::to_integer<int>(test(b8, b2)) == 10, "");
+
+}