This is an attempt to make GHC build reproducible. The name of .c files may end up in the resulting binary (in the debug section), but not the directory. Instead of using the process id, create a hash from the command line arguments, and assume that is going to be unique. Index: ghc/compiler/main/SysTools.hs =================================================================== --- ghc.orig/compiler/main/SysTools.hs 2015-11-02 17:23:05.410365013 +0100 +++ ghc/compiler/main/SysTools.hs 2015-11-02 17:23:05.410365013 +0100 @@ -66,6 +66,7 @@ import Util import DynFlags import Exception +import Fingerprint import Data.IORef import Control.Monad @@ -1152,8 +1153,8 @@ mapping <- readIORef dir_ref case Map.lookup tmp_dir mapping of Nothing -> do - pid <- getProcessID - let prefix = tmp_dir "ghc" ++ show pid ++ "_" + pid <- getStableProcessID + let prefix = tmp_dir "ghc" ++ pid ++ "_" mask_ $ mkTempDir prefix Just dir -> return dir where @@ -1531,6 +1532,13 @@ getProcessID = System.Posix.Internals.c_getpid >>= return . fromIntegral #endif +-- Debian-specific hack to get reproducible output, by not using the "random" +-- pid, but rather something determinisic +getStableProcessID :: IO String +getStableProcessID = do + args <- getArgs + return $ take 4 $ show $ fingerprintString $ unwords args + -- Divvy up text stream into lines, taking platform dependent -- line termination into account. linesPlatform :: String -> [String]