[ ghc-Bugs-1246483 ] Template Haskell panic with class names

Bugs item #1246483, was opened at 2005-07-28 03:09
Message generated for change (Settings changed) made by simonpj
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Category: Template Haskell
Group: 6.4
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Wolfgang Thaller (wthaller)
Assigned to: Simon Peyton Jones (simonpj)
Summary: Template Haskell panic with class names

Initial Comment:
File Bug.hs:
module Bug where
foo = ''Show

Compile using:
ghc -c -fth Bug.hs

Result:
ghc-6.4.1: panic! (the `impossible' happened, GHC version 6.4.1):
        lookupDeprec GHCziShow.Show{tc 2h}

Please report it as a compiler bug to glasgow-haskell-
bugs@xxxxxxxxxxx,
or http://sourceforge.net/projects/ghc/.

The panic does not happen if the type class or one of its method is 
actually used in the same module.

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>Comment By: Simon Peyton Jones (simonpj)
Date: 2005-08-09 17:00

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Urk.  A typo.  Fixed again!

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Comment By: Wolfgang Thaller (wthaller)
Date: 2005-08-02 22:13

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The fix causes more problems:

$ cat THClassName.hs 
module THClassName where

class Foo a

baz = ''Foo

$ ghc -c -fth THClassName.hs 
Bad interface file: THClassName.hi
    THClassName.hi: openBinaryFile: does not exist (No such file or 
directory)

It tries to load the .hi file that doesn't yet exist, which it probably 
shouldn't do.

Wolfgang

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Comment By: Simon Peyton Jones (simonpj)
Date: 2005-07-28 13:53

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Good point. I'd fixed this in the HEAD but not the 6.4 branch.

Simon

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