#15513: How to pass "-hide-all-packages" to the GHC API? -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: 8.6.1 Component: Documentation | Version: 8.4.3 Resolution: | Keywords: environment | file API Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #15541 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by lspitzner): * related: => #15541 Old description:

In brittany, we have make use of the GHC API e.g. in the following fashion:

{{{#!hs parseModuleFromString :: [String] -> System.IO.FilePath -> (GHC.DynFlags -> IO (Either String a)) -> String -> IO (Either String (ExactPrint.Anns, GHC.ParsedSource, a)) parseModuleFromString args fp dynCheck str = mask_ $ ExactPrint.ghcWrapper $ ExceptT.runExceptT $ do dflags0 <- lift $ ExactPrint.initDynFlagsPure fp str (dflags1, leftover, warnings) <- lift $ GHC.parseDynamicFlagsCmdLine dflags0 (GHC.noLoc <$> args) when (not $ null leftover) $ ExceptT.throwE $ "when parsing ghc flags: leftover flags: " ++ show (leftover <&> \(L _ s) -> s) when (not $ null warnings) $ ExceptT.throwE $ "when parsing ghc flags: encountered warnings: " ++ show (warnings <&> warnExtractorCompat) dynCheckRes <- ExceptT.ExceptT $ liftIO $ dynCheck dflags1 let res = ExactPrint.parseModuleFromStringInternal dflags1 fp str case res of Left (span, err) -> ExceptT.throwE $ show span ++ ": " ++ err Right (a , m ) -> pure (a, m, dynCheckRes) }}}

This code unfortunately picks up "package environment files", which I take it is not at all necessary for this use-case: Brittany only requires parsing functionality, so external packages should be irrelevant. "Unfortunately", because the package environment files can easily become stale, which in turn breaks the API.

The users' guide mentions the "-hide-all-packages" flag, but my attempts to pass this to the API so far have failed. What I have tried is calling `parseDynamicFlagsCmdLine` with "-hide-all-packages" as an argument, and using the resulting dynflags afterwards. This appears to be without effect, I think even when it is the first thing executed inside of `runGhc`.

New description: In brittany, we have make use of the GHC API e.g. in the following fashion: {{{#!hs parseModuleFromString :: [String] -> System.IO.FilePath -> (GHC.DynFlags -> IO (Either String a)) -> String -> IO (Either String (ExactPrint.Anns, GHC.ParsedSource, a)) parseModuleFromString args fp dynCheck str = mask_ $ ExactPrint.ghcWrapper $ ExceptT.runExceptT $ do dflags0 <- lift $ ExactPrint.initDynFlagsPure fp str (dflags1, leftover, warnings) <- lift $ GHC.parseDynamicFlagsCmdLine dflags0 (GHC.noLoc <$> args) when (not $ null leftover) $ ExceptT.throwE $ "when parsing ghc flags: leftover flags: " ++ show (leftover <&> \(L _ s) -> s) when (not $ null warnings) $ ExceptT.throwE $ "when parsing ghc flags: encountered warnings: " ++ show (warnings <&> warnExtractorCompat) dynCheckRes <- ExceptT.ExceptT $ liftIO $ dynCheck dflags1 let res = ExactPrint.parseModuleFromStringInternal dflags1 fp str case res of Left (span, err) -> ExceptT.throwE $ show span ++ ": " ++ err Right (a , m ) -> pure (a, m, dynCheckRes) }}} This code unfortunately picks up "package environment files", which I take it is not at all necessary for this use-case: Brittany only requires parsing functionality, so external packages should be irrelevant. "Unfortunately", because the package environment files can easily become stale, which in turn breaks the API. The users' guide mentions the "-hide-all-packages" flag, but my attempts to pass this to the API so far have failed. What I have tried is calling `parseDynamicFlagsCmdLine` with "-hide-all-packages" as an argument, and using the resulting dynflags afterwards. This appears to be without effect, ~~I think even when it is the first thing executed inside of `runGhc`~~ (not entirely correct, see below). -- Comment: {{{#!hs dflags0 <- GHC.getSessionDynFlags (dflags1, [], []) <- GHC.parseDynamicFlagsCmdLine dflags0 [GHC.noLoc "-hide-all-packages"] GHC.setSessionDynFlags dflags1 }}} must be called before any other invocation of `setSessionDynFlags`. I'll leave this open as it is unconfirmed and as a reminder to add this snippet or a better version to the appropriate (API) docs. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15513#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler