Fix rename.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123604 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Unix/PathV2.inc b/lib/Support/Unix/PathV2.inc
index 056708a..03ff283 100644
--- a/lib/Support/Unix/PathV2.inc
+++ b/lib/Support/Unix/PathV2.inc
@@ -230,8 +230,17 @@
   StringRef f = from.toNullTerminatedStringRef(from_storage);
   StringRef t = to.toNullTerminatedStringRef(to_storage);
 
-  if (::rename(f.begin(), t.begin()) == -1)
-    return error_code(errno, system_category());
+  if (::rename(f.begin(), t.begin()) == -1) {
+    // If it's a cross device link, copy then delete, otherwise return the error
+    if (errno == EXDEV) {
+      if (error_code ec = copy_file(from, to, copy_option::overwrite_if_exists))
+        return ec;
+      bool Existed;
+      if (error_code ec = remove(from, Existed))
+        return ec;
+    } else
+      return error_code(errno, system_category());
+  }
 
   return success;
 }