Merging r367084:

zmodem · zmodem · commit 2a3980935ded · 2019-08-14T13:14:17.000Z
------------------------------------------------------------------------ r367084 | kongyi | 2019-07-26 07:17:14 +0200 (Fri, 26 Jul 2019) | 6 lines Fix macOS build after r358716 COPYFILE_CLONE is only defined on newer macOS versions, using it without check breaks build on systems running legacy OS and toolchain. Differential Revision: https://reviews.llvm.org/D65317 ------------------------------------------------------------------------ llvm-svn: 368848
diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
@@ -1200,7 +1200,7 @@ namespace fs {
 /// implementation.
 std::error_code copy_file(const Twine &From, const Twine &To) {
   uint32_t Flag = COPYFILE_DATA;
-#if __has_builtin(__builtin_available)
+#if __has_builtin(__builtin_available) && defined(COPYFILE_CLONE)
   if (__builtin_available(macos 10.12, *)) {
     bool IsSymlink;
     if (std::error_code Error = is_symlink_file(From, IsSymlink))
