Great, thanks. I've added that link to the user-documentation page for the GHC API, here http://haskell.org/haskellwiki/GHC/As_a_library#Links Please do elaborate that page, which is a bit thin at the moment. It should be easier to find supporting info about the GHC API. Simon | -----Original Message----- | From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users- | bounces@haskell.org] On Behalf Of Ranjit Jhala | Sent: 14 May 2011 17:52 | To: ghc-users | Subject: Re: crash caused by generic visitor (?) | | Hi all, | | my apologies. Looks like the issue (and a fix!) is described here | | http://mistuke.wordpress.com/category/vsx/ | | Thanks, | | Ranjit. | | On May 13, 2011, at 4:34 PM, Ranjit Jhala wrote: | | > Hi all, | > | > I'm trying to extract the set of identifiers that are read in given | > source file. To this end, I wrote the following code (full source at end.) | > | > ------------------------------------------------------------------------ | > main | > = do fname <- (!! 0) `fmap` getArgs | > tcm <- loadTypecheckedSource fname | > putStrLn $ showPpr tcm -- this works fine | > putStrLn $ showPpr $ allIds tcm -- this causes the crash | > return () | > | > allIds :: Data a => a -> [Id] | > allIds = listify (\x -> case (x :: Id) of _ -> True) | > ------------------------------------------------------------------------ | > | > and where: | > | > loadTypecheckedSource :: FilePath -> IO TypecheckedSource | > | > unfortunately, when I compile and run it, I get the dreaded: | > | > Bug: Bug: panic! (the 'impossible' happened) | > (GHC version 7.0.3 for i386-unknown-linux): | > placeHolderNames | > | > Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug | > | > Turns out that the problem is when the file contains a type annotation. | > That is, | > | > ./Bug Test00.hs | > | > crashes, when Test00.hs is: | > | > module Test where | > | > x :: Int | > x = 0 | > | > but does not crash when the file is: | > | > module Test where | > | > x = 0 | > | > Can anyone tell me why listify chokes in the latter case? (And how one might | > get around the problem?) I include the full source below (compiled with: ghc --make | Bug, using ghc 7.0.3) | > | > Thanks! | > | > Ranjit. | > | > ----------------------------------------------------------------------------------- | ------------------- | > import GHC | > import Outputable | > import DynFlags (defaultDynFlags) | > import GHC.Paths (libdir) | > | > import System.Environment (getArgs) | > import Control.Monad | > import qualified Data.List as L | > import Data.Data | > import Data.Generics.Schemes (listify) | > | > main | > = do fname <- (!! 0) `fmap` getArgs | > tcm <- loadTypecheckedSource fname | > putStrLn $ showPpr tcm -- this works fine | > putStrLn $ showPpr $ allIds tcm -- this causes the crash | > return () | > | > allIds :: Data a => a -> [Id] | > allIds = listify (\x -> case (x :: Id) of _ -> True) | > | > loadTypecheckedSource :: FilePath -> IO TypecheckedSource | > loadTypecheckedSource fname | > = defaultErrorHandler defaultDynFlags $ | > runGhc (Just libdir) $ do | > df <- getSessionDynFlags | > setSessionDynFlags df | > tgt <- guessTarget fname Nothing | > setTargets [tgt] | > load LoadAllTargets | > res <- load LoadAllTargets | > if failed res | > then pprPanic "Load Failed!!" (text "AAARGH!") | > else tm_typechecked_source `fmap` getTypecheckedModule fname | > | > findModSummary :: GhcMonad m => FilePath -> m ModSummary | > findModSummary fname | > = do msums <- depanal [] False | > case L.find ((fname ==) . ms_hspp_file) msums of | > Just msum -> return msum | > Nothing -> pprPanic "ModuleName Lookup Failed!!" (text "AARGHC!") | > | > getTypecheckedModule :: GhcMonad m => FilePath -> m TypecheckedModule | > getTypecheckedModule = findModSummary >=> parseModule >=> typecheckModule | > | > | > | | | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users