From 5eaf1e1be289245267263536f5464e40d2a677c0 Mon Sep 17 00:00:00 2001
From: Rolf Eike Beer <eb@emlix.com>
Date: Mon, 9 Sep 2019 09:09:48 +0200
Subject: cmSystemTools: introduce MoveFileIfDifferent()

---
 Source/cmSystemTools.cxx | 12 ++++++++++++
 Source/cmSystemTools.h   |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index b7287d9..074faa5 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -855,6 +855,18 @@ bool cmSystemTools::RenameFile(const std::string& oldname,
 #endif
 }
 
+void cmSystemTools::MoveFileIfDifferent(const std::string& source,
+                                        const std::string& destination)
+{
+  if (FilesDiffer(source, destination)) {
+    if (RenameFile(source, destination)) {
+      return;
+    }
+    CopyFileAlways(source, destination);
+  }
+  RemoveFile(source);
+}
+
 std::string cmSystemTools::ComputeFileHash(const std::string& source,
                                            cmCryptoHash::Algo algo)
 {
diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 863db3f..8ca4939 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -131,6 +131,10 @@ public:
   static bool RenameFile(const std::string& oldname,
                          const std::string& newname);
 
+  //! Rename a file if contents are different, delete the source otherwise
+  static void MoveFileIfDifferent(const std::string& source,
+                                  const std::string& destination);
+
   //! Compute the hash of a file
   static std::string ComputeFileHash(const std::string& source,
                                      cmCryptoHash::Algo algo);
-- 
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