From 835896e985a0333e56623d16761dfa2b37d0a7e2 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 20 Apr 2021 12:11:50 -0400
Subject: cmake: Improve error message when failing to update generation
 timestamp

Include the underlying system error description.

Issue: #21571, #22086
---
 Source/cmake.cxx | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index af3a504..d24e268 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -3074,12 +3074,16 @@ static bool cmakeCheckStampFile(const std::string& stampName)
     cmsys::ofstream stamp(stampTemp.c_str());
     stamp << "# CMake generation timestamp file for this directory.\n";
   }
-  if (cmSystemTools::RenameFile(stampTemp, stampName)) {
+  std::string err;
+  if (cmSystemTools::RenameFile(stampTemp, stampName,
+                                cmSystemTools::Replace::Yes, &err) ==
+      cmSystemTools::RenameResult::Success) {
     // CMake does not need to re-run because the stamp file is up-to-date.
     return true;
   }
   cmSystemTools::RemoveFile(stampTemp);
-  cmSystemTools::Error("Cannot restore timestamp " + stampName);
+  cmSystemTools::Error(
+    cmStrCat("Cannot restore timestamp \"", stampName, "\": ", err));
   return false;
 }
 
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