8.8.x change in lookupModule / findModule semantics?
dxld at darkboxed.org
Thu Feb 27 23:20:47 UTC 2020
On Thu, Feb 27, 2020 at 08:37:12PM +0000, Tseen She wrote:
> setTargets [Target (TargetFile "Main.hs" (Just $ Hsc HsSrcFile))
> False (Just (stringToStringBuffer buffer, t))]
> i.e. an explicit phase.
> I will just use Nothing in my TargetFile. Was this an intended change?
I found the reason for the change, my commit 0f9ec9d1ff ("Allow using
tagetContents for modules needing preprocessing") removes the special
casing in `preprocessFile` for in-memory buffers:
-preprocessFile hsc_env src_fn mb_phase (Just (buf, _time))
- = do
- let dflags = hsc_dflags hsc_env
- let local_opts = getOptions dflags buf src_fn
- (dflags', leftovers, warns)
- <- parseDynamicFilePragma dflags local_opts
It used to do a `parseDynamicFilePragma` which parses the LANGUAGE and
I think this change is actually for the better though, as this dflags
modification does not occur with a regular file, so we're actually being
I just tested this out and when setting the phase but not passing a buffer
8.6 will also fail to get the pragma in the ModSummary. When not giving an
explicit phase it works for 8.6, 8.8, with and without in-memory buffers
though. So I think that is the proper solution here, unless you can think
of a reason running the rest of the pipeline is a problem in this case?
On Thu, Feb 27, 2020 at 08:49:43PM +0000, Tseen She wrote:
> It is, however, a shame that lookupModule seems to require the entire file
> to parse / typecheck. That also smells like a regression, but not one that
> impacts me anymore.
I would still like to reproduce your problem but I'm again not sure how
you're triggering it, this is what I have so far:
-- $ ghc -package ghc -package ghc-paths FindModule.hs
module Main where
import GHC.Paths (libdir)
main :: IO ()
main = do
defaultErrorHandler defaultFatalMessager defaultFlushOut $ do
runGhc (Just libdir) $ do
dflags0 <- getSessionDynFlags
(dflags1, _, _)
<- parseDynamicFlags dflags0 $ map noLoc ["-package", "base"]
_ <- setSessionDynFlags dflags1
setTargets [Target (TargetFile "Main.hs" Nothing) False Nothing]
_ <- load LoadAllTargets
m <- findModule (mkModuleName "Main") Nothing
liftIO $ print $ (unitIdFS (moduleUnitId m), moduleNameFS (moduleName m))
Running it with 8.8 and 8.4 i get the same results:
$ ghc-$ver -package ghc -package ghc-paths FindModule.hs
$ echo 'main = return()' > Main.hs # a working file
$ echo '=' > Main.hs # a syntax error
parse error on input ‘=’
Perhaps you need a 'let' in a 'do' block?
e.g. 'let x = 5' instead of 'x = 5'
1 | =
<command line>: module is not loaded: ‘Main’ (Main.hs)
so this seems to be consistent?
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