From 182f4fb8dc8d8b104ed537af324d76cc0079e882 Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Sun, 14 Apr 2013 15:49:19 -0400
Subject: avoid updating a file if the old splice is the same as the new

---
 Build/EvilSplicer.hs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'Build')

diff --git a/Build/EvilSplicer.hs b/Build/EvilSplicer.hs
index 3927fcc5a..2a1984ed6 100644
--- a/Build/EvilSplicer.hs
+++ b/Build/EvilSplicer.hs
@@ -35,6 +35,7 @@ import Data.Char
 import System.Environment
 import System.FilePath
 import System.Directory
+import Control.Monad
 
 import Utility.Monad
 import Utility.Misc
@@ -179,7 +180,10 @@ applySplices destdir imports l@(first:_) = do
 	putStrLn $ "splicing " ++ f
 	lls <- map (++ "\n") . lines <$> readFileStrict f
 	createDirectoryIfMissing True (parentDir dest)
-	writeFile dest $ concat $ addimports $ expand lls l
+	let newcontent = concat $ addimports $ expand lls l
+	oldcontent <- catchMaybeIO $ readFile dest
+	when (oldcontent /= Just newcontent) $
+		writeFile dest newcontent
   where
   	expand lls [] = lls
   	expand lls (s:rest) = expand (expandSplice s lls) rest
-- 
cgit v1.2.3