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, 2 insertions, 4 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index b4706a3..f1c48cc 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -3417,8 +3417,7 @@ std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
         file << pchEpilogue << "\n";
       }
     }
-    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
-    cmSystemTools::RemoveFile(filename_tmp);
+    cmSystemTools::MoveFileIfDifferent(filename_tmp, filename);
   }
   return inserted.first->second;
 }
@@ -3451,8 +3450,7 @@ std::string cmGeneratorTarget::GetPchSource(const std::string& config,
       cmGeneratedFileStream file(filename_tmp);
       file << "/* generated by CMake */\n";
     }
-    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
-    cmSystemTools::RemoveFile(filename_tmp);
+    cmSystemTools::MoveFileIfDifferent(filename_tmp, filename);
   }
   return inserted.first->second;
 }