[PATCH] D35472: Implement P0463R1: "Endian just Endian"

[Marshall Clow via Phabricator via cfe-commits]

mclow.lists updated this revision to Diff 115714.
mclow.lists added a comment.

Fixed test and #ifdef guard


https://reviews.llvm.org/D35472

Files:
  include/type_traits
  test/std/utilities/meta/meta.type.synop/endian.pass.cpp


Index: test/std/utilities/meta/meta.type.synop/endian.pass.cpp
===================================================================
--- test/std/utilities/meta/meta.type.synop/endian.pass.cpp
+++ test/std/utilities/meta/meta.type.synop/endian.pass.cpp
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+
+// enum class endian;
+
+#include <type_traits>
+#include <cstring>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main() {
+    typedef std::endian E;
+    static_assert(std::is_enum<std::endian>::value, "");
+
+// Check that E is a scoped enum by checking for conversions.
+    typedef std::underlying_type<std::endian>::type UT;
+    static_assert(!std::is_convertible<std::endian, UT>::value, "");
+
+// test that the enumeration values exist
+    static_assert( std::endian::little == std::endian::little );
+    static_assert( std::endian::big    == std::endian::big );
+    static_assert( std::endian::native == std::endian::native );
+    static_assert( std::endian::little != std::endian::big );
+
+//  Technically not required, but true on all existing machines
+    static_assert( std::endian::native == std::endian::little || 
+                   std::endian::native == std::endian::big );
+    
+//  Try to check at runtime
+    {
+    uint32_t i = 0x01020304;
+    char c[4];
+    static_assert(sizeof(i) == sizeof(c));
+    std::memcpy(c, &i, sizeof(c));
+
+    assert ((c[0] == 1) == (std::endian::native == std::endian::big));
+    }
+}
Index: include/type_traits
===================================================================
--- include/type_traits
+++ include/type_traits
@@ -4738,6 +4738,21 @@
 
 #endif
 
+#if _LIBCPP_STD_VER > 17
+enum class endian
+{
+    little = 0xDEAD,
+    big    = 0xFACE,
+#if _LIBCPP_LITTLE_ENDIAN
+    native = little
+#elif _LIBCPP_BIG_ENDIAN
+    native = big
+#else
+    native = 0xCAFE
+#endif
+};
+#endif
+
 _LIBCPP_END_NAMESPACE_STD
 
 #if _LIBCPP_STD_VER > 14


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