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|
{-# LANGUAGE RecordWildCards #-}
-- | This module manages storing the various GHC option flags in a modules
-- interface file as part of the recompilation checking infrastructure.
module FlagChecker (
fingerprintDynFlags
) where
import Binary
import BinIface ()
import DynFlags
import HscTypes
import Module
import Name
import Fingerprint
-- import Outputable
import qualified Data.IntSet as IntSet
import System.FilePath (normalise)
-- | Produce a fingerprint of a @DynFlags@ value. We only base
-- the finger print on important fields in @DynFlags@ so that
-- the recompilation checker can use this fingerprint.
fingerprintDynFlags :: DynFlags -> Module -> (BinHandle -> Name -> IO ())
-> IO Fingerprint
fingerprintDynFlags dflags@DynFlags{..} this_mod nameio =
let mainis = if mainModIs == this_mod then Just mainFunIs else Nothing
-- see #5878
-- pkgopts = (thisPackage dflags, sort $ packageFlags dflags)
safeHs = setSafeMode safeHaskell
-- oflags = sort $ filter filterOFlags $ flags dflags
-- *all* the extension flags and the language
lang = (fmap fromEnum language,
IntSet.toList $ extensionFlags)
-- -I, -D and -U flags affect CPP
cpp = (map normalise includePaths, opt_P dflags ++ picPOpts dflags)
-- normalise: eliminate spurious differences due to "./foo" vs "foo"
-- Note [path flags and recompilation]
paths = [ hcSuf ]
-- -fprof-auto etc.
prof = if gopt Opt_SccProfilingOn dflags then fromEnum profAuto else 0
in -- pprTrace "flags" (ppr (mainis, safeHs, lang, cpp, paths)) $
computeFingerprint nameio (mainis, safeHs, lang, cpp, paths, prof)
{- Note [path flags and recompilation]
There are several flags that we deliberately omit from the
recompilation check; here we explain why.
-osuf, -odir, -hisuf, -hidir
If GHC decides that it does not need to recompile, then
it must have found an up-to-date .hi file and .o file.
There is no point recording these flags - the user must
have passed the correct ones. Indeed, the user may
have compiled the source file in one-shot mode using
-o to specify the .o file, and then loaded it in GHCi
using -odir.
-stubdir
We omit this one because it is automatically set by -outputdir, and
we don't want changes in -outputdir to automatically trigger
recompilation. This could be wrong, but only in very rare cases.
-i (importPaths)
For the same reason as -osuf etc. above: if GHC decides not to
recompile, then it must have already checked all the .hi files on
which the current module depends, so it must have found them
successfully. It is occasionally useful to be able to cd to a
different directory and use -i flags to enable GHC to find the .hi
files; we don't want this to force recompilation.
The only path-related flag left is -hcsuf.
-}
|
