From eaf9236540e46688df3d014b7ade06edb085a9f3 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 13 Jul 2026 03:04:29 +0000
Subject: [PATCH] fix: only write install_tactic.deps when content changes to
 avoid unnecessary rebuilds

---
 cmake/z3_add_component.cmake | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/cmake/z3_add_component.cmake b/cmake/z3_add_component.cmake
index 962b02f684..e3dc2dd80c 100644
--- a/cmake/z3_add_component.cmake
+++ b/cmake/z3_add_component.cmake
@@ -273,7 +273,19 @@ macro(z3_add_install_tactic_rule)
   unset(_component_tactic_header_files)
 
   string(REPLACE ";" "\n" _tactic_header_files "${_tactic_header_files}")
-  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/install_tactic.deps" ${_tactic_header_files})
+  # Only write the deps file if content has changed to avoid unnecessary rebuilds
+  # (file(WRITE) always updates the timestamp even if content is unchanged)
+  set(_install_tactic_deps_file "${CMAKE_CURRENT_BINARY_DIR}/install_tactic.deps")
+  if (EXISTS "${_install_tactic_deps_file}")
+    file(READ "${_install_tactic_deps_file}" _install_tactic_deps_old)
+  else()
+    set(_install_tactic_deps_old "")
+  endif()
+  if (NOT _install_tactic_deps_old STREQUAL "${_tactic_header_files}")
+    file(WRITE "${_install_tactic_deps_file}" "${_tactic_header_files}")
+  endif()
+  unset(_install_tactic_deps_old)
+  unset(_install_tactic_deps_file)
   add_custom_command(OUTPUT "install_tactic.cpp"
     COMMAND "${Python3_EXECUTABLE}"
     "${PROJECT_SOURCE_DIR}/scripts/mk_install_tactic_cpp.py"