From e36a444c541d5dd47857321dd55bae5e1bdf51c9 Mon Sep 17 00:00:00 2001
From: Gustavo Sverzut Barbieri <barbieri@profusion.mobi>
Date: Mon, 23 Jan 2017 14:33:30 -0200
Subject: [PATCH] cmake: only update config_headers.h if contents changed.

Generate to a temporary location and avoid touching the original file
if it's unchanged. This way we play nicer with build system that
regenerate objects based on file timestamps.
---
 cmake/helpers/CommonHeaderChecks.cmake | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/cmake/helpers/CommonHeaderChecks.cmake b/cmake/helpers/CommonHeaderChecks.cmake
index ac7dba8dff..a92dabd9b7 100644
--- a/cmake/helpers/CommonHeaderChecks.cmake
+++ b/cmake/helpers/CommonHeaderChecks.cmake
@@ -77,5 +77,19 @@ HEADER_CHECK(libunwind.h HAVE_UNWIND)
 HEADER_CHECK(mtrace.h HAVE_MTRACE_H)
 
 function(EFL_HEADER_CHECKS_FINALIZE file)
-    file(WRITE ${file} ${HEADER_FILE_CONTENT})
-endfunction()
\ No newline at end of file
+  file(WRITE ${file}.new ${HEADER_FILE_CONTENT})
+  if (NOT EXISTS ${file})
+    file(RENAME ${file}.new ${file})
+    message(STATUS "${file} was generated.")
+  else()
+    file(MD5 ${file}.new _new_md5)
+    file(MD5 ${file} _old_md5)
+    if(_new_md5 STREQUAL _old_md5)
+      message(STATUS "${file} is unchanged.")
+    else()
+      file(REMOVE ${file})
+      file(RENAME ${file}.new ${file})
+      message(STATUS "${file} was updated.")
+    endif()
+  endif()
+endfunction()