David You'll recall this interchange about the AMP patch | > Don't use tryTc in tcLookupClassMaybe -- it's a sledgehammer to crack | > a nut. The only classes you are looking up are monad, applicative, | > alternative, and they will always be found -- or at least if not we | > have a problem, and tcLookupClass will rightly report an error. So I | > see no need for this tryTc and matching on maybes. | | The use of tryTc there fixed the problem we (me and Dan) discussed | recently on ghc-devs: the testsuite errors with | | GHC/Base.lhs:1:1: | GHC internal error: ‛GHC.Base.Monad’ is not in scope during type | checking, but it passed the renamer tcl_env of environment: [] I think I know roughly what's happening. Clearly we can't look up Monad in the type environment until we've typechecked that class. But the amp-warning stuff will try to look it up *regardless*. Ditto Applicative. Trying to look it up will make GHC look for Control.Applicative.hi, which won't exist until Control.Applicative is compiled. Hence the error. I'll tidy this up with a bit of refactoring Simon | -----Original Message----- | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Simon | Peyton-Jones | Sent: 04 September 2013 12:25 | To: David Luposchainsky | Cc: ghc-devs@haskell.org | Subject: RE: AMP (#8004) almost finished, review would be nice | | | GHC/Base.lhs:1:1: | | GHC internal error: ‛GHC.Base.Monad’ is not in scope during type | | checking, but it passed the renamer tcl_env of environment: [] | | I don't understand this. The message comes from TcEnv.notFound, | presumably from tcLookupGlobal. But the latter only calls notFound for | an internal name (which this is not), or when compiling the very same | module (GHC.Base in this case). But I think you are saying this message | | So something mysterious is going on. Can you try the obvious thing | again and let's look at it? | | (I suppose you could commit as-is (when you've unravelled the validation | questions) so that I can see it too.) | | Simon | | | | | (and the full build errored with "missing interfaces for GHC.Base"). | The | | maybe business fixed this. (Subject of the discussion: "Cannot make | | ghc: Failed to load interface for GHC.Base") | | | | Also note that the Prelude is not necessarily imported, so I think the | | lookups here can fail regardless of the issue mentioned before. | | | | | | | | > I don't see any documentation. | | | | In what sense? More comments, longer function headers? I thought the | | names used were clear, with comments giving an overview over longer | | sections. (If you're talking about Haddock: the AMP functions are not | | exported, hence no HTML docs. tcAmpWarn is called from inside | | tcTopSrcDecls in the same module.) | | | | | | | | > I don't know about this validation stuff; maybe others can help. | | > Why not *not* add -fno-warn-amp to GcStage1HcOpts? | | | | The flag is mysteriously passed to the existing GHC, i.e. it appears | | when building phase 1. However, the current compiler doesn't know | about | | the flag and fails. (This was my initial attempt.) | | | | | | | | Thanks for the advice, | | David/quchen | _______________________________________________ | ghc-devs mailing list | ghc-devs@haskell.org | http://www.haskell.org/mailman/listinfo/ghc-devs