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Re: [GHC] #906: "the `impossible' happened: Maybe.fromJust: Nothing" when u: msg#00117

lang.haskell.glasgow.bugs

Subject: Re: [GHC] #906: "the `impossible' happened: Maybe.fromJust: Nothing" when using {-# SOURCE #-}

#906: "the `impossible' happened: Maybe.fromJust: Nothing" when using {-# SOURCE
#-}
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Reporter: Misha Aizatulin <avatar@xxxxxx> | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.4.2
Severity: normal | Resolution:
Keywords: | Os: Linux
Difficulty: Unknown | Architecture: x86
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Comment (by simonpj):

We know what is going on here; module A is being compiled before A.hs-
boot, so when the latter is compiled it overwrites the in-memory record of
the object code of A.

Solution: add edge from A.hs-boot to A.hs. This is a Good Thing anyway,
because A.hs-boot should not depend on A.hs (i.e. adding the edge prevents
another odd case). But adding the edge also means that A.hs-boot will
never overwrite A.hs in the HPT.


Guaranteeing such a message is a bit more work. See Task #914

--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/906>
GHC <http://www.haskell.org/ghc/>
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