From a8cf09d49aa8dfed35402e1358a3ea7aa1687045 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 17 Feb 2026 17:05:42 -0500
Subject: [PATCH] PCH: Fix regression in REUSE_FROM that copies the `.pdb` too
 often

Since commit 99bdf2ae16 (cmLocalGenerator: add PDB copying dependency on
its script, 2025-06-16, v4.2.0-rc1~481^2~8) the copy is repeated
whenever the copying script is updated.  Avoid updating the copy script
timestamp when it does not change.

Fixes: #27608
---
 Source/cmLocalGenerator.cxx | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 83dc6b1dca..473de56078 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2914,6 +2914,7 @@ void cmLocalGenerator::CopyPchCompilePdb(
   std::string const copy_script = cmStrCat(target->GetSupportDirectory(),
                                            "/copy_idb_pdb_", config, ".cmake");
   cmGeneratedFileStream file(copy_script);
+  file.SetCopyIfDifferent(true);
 
   file << "# CMake generated file\n";