From eaa420e99c86cb700f37fd21420ab86adeed798f Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 7 Jul 2020 13:39:35 -0400
Subject: cmGeneratedFileStream: Use random temporary file extension by default

Avoid collisions with project-specified files named with `.tmp`.

Issue: #20873
---
 Source/cmGeneratedFileStream.cxx | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Source/cmGeneratedFileStream.cxx b/Source/cmGeneratedFileStream.cxx
index 119067e..345f0ba 100644
--- a/Source/cmGeneratedFileStream.cxx
+++ b/Source/cmGeneratedFileStream.cxx
@@ -129,7 +129,9 @@ void cmGeneratedFileStreamBase::Open(std::string const& name)
   if (!this->TempExt.empty()) {
     this->TempName += this->TempExt;
   } else {
-    this->TempName += "tmp";
+    char buf[64];
+    sprintf(buf, "tmp%05x", cmSystemTools::RandomSeed() & 0xFFFFF);
+    this->TempName += buf;
   }
 
   // Make sure the temporary file that will be used is not present.
-- 
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