From 8d7ab23b4965cc8ae74e94f8801a95b0ba306518 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Linse?= <bjorn.linse@gmail.com>
Date: Tue, 9 Feb 2016 22:57:48 +0100
Subject: [PATCH] build system: avoid more unneccesary recompiles

---
 scripts/gendeclarations.lua | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/scripts/gendeclarations.lua b/scripts/gendeclarations.lua
index 4e74e4e301..637f4cdffa 100755
--- a/scripts/gendeclarations.lua
+++ b/scripts/gendeclarations.lua
@@ -239,23 +239,24 @@ end
 non_static = non_static .. footer
 static = static .. footer
 
-local F
-F = io.open(static_fname, 'w')
-F:write(static)
-F:close()
 
--- Before generating the non-static headers, check if the current file(if
--- exists) is different from the new one. If they are the same, we won't touch
--- the current version to avoid triggering an unnecessary rebuilds of modules
+-- Before generating the headers, check if the current file (if exists) is
+-- different from the new one. If they are the same, we won't touch the
+-- current version to avoid triggering an unnecessary rebuilds of modules
 -- that depend on this one
-F = io.open(non_static_fname, 'r')
-if F ~= nil then
-  if F:read('*a') == non_static then
-    os.exit(0)
+local update_changed = function (fname, contents)
+  local F = io.open(fname, 'r')
+  if F ~= nil then
+    if F:read('*a') == contents then
+      return
+    end
+    io.close(F)
   end
-  io.close(F)
+
+  F = io.open(fname, 'w')
+  F:write(contents)
+  F:close()
 end
 
-F = io.open(non_static_fname, 'w')
-F:write(non_static)
-F:close()
+update_changed(static_fname, static)
+update_changed(non_static_fname, non_static)