use cmSystemTools::MoveFileIfDifferent()

This is better than doing CopyFileIfDifferent() followed by RemoveFile() in
two ways:

 - it is more efficient, as it avoids disk I/O for the data, even if the
   files here are usually small
 - it is atomic, so an abort during the copy will not leave a destination file
   with partial data behind

1 files changed, 1 insertions, 2 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 9152e94..3d8c3fb 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2275,8 +2275,7 @@ void cmLocalGenerator::AddUnityBuild(cmGeneratorTarget* target,
           }
         }
       }
-      cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
-      cmSystemTools::RemoveFile(filename_tmp);
+      cmSystemTools::MoveFileIfDifferent(filename_tmp, filename);
 
       target->AddSource(filename, true);