Base isPodLike on is_trivially_copyable for GCC 5 and MSVC

It would be nice to get rid of the version checks here, but that will
have to wait until libstdc++ is upgraded to 5.0 everywhere ...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230021 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Support/type_traits.h b/include/llvm/Support/type_traits.h
index 70953a9cb70e4023c527cd75c23173d5011bb8ee..1befe92bb1c4879e098c57eabfe933bad4f4caca 100644 (file)
--- a/include/llvm/Support/type_traits.h
+++ b/include/llvm/Support/type_traits.h
@@ -28,9 +28,17 @@ namespace llvm {
 /// type can be copied around with memcpy instead of running ctors etc.
 template <typename T>
 struct isPodLike {
-#if __has_feature(is_trivially_copyable)
+  // std::is_trivially copyable is available in libc++ with clang, libstdc++
+  // that comes with GCC 5 and MSVC 2013.
+#if (__has_feature(is_trivially_copyable) && defined(_LIBCPP_VERSION)) ||      \
+    (defined(__GNUC__) && __GNUC__ >= 5) || defined(_MSC_VER)
   // If the compiler supports the is_trivially_copyable trait use it, as it
   // matches the definition of isPodLike closely.
+  static const bool value = std::is_trivially_copyable<T>::value;
+#elif __has_feature(is_trivially_copyable)
+  // Use the internal name if the compiler supports is_trivially_copyable but we
+  // don't know if the standard library does. This is the case for clang in
+  // conjunction with libstdc++ from GCC 4.x.
   static const bool value = __is_trivially_copyable(T);
 #else
   // If we don't know anything else, we can (at least) assume that all non-class