[ ghc-Bugs-1281130 ] "class A where a :: A -> Int" panics GHC 6.4

Bugs item #1281130, was opened at 2005-09-03 06:06
Message generated for change (Settings changed) made by simonpj
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Category: None
Group: None
>Status: Closed
>Resolution: Duplicate
Priority: 5
Submitted By: Carlos Eduardo Scheidegger (carlossch)
Assigned to: Nobody/Anonymous (nobody)
Summary: "class A where a :: A -> Int" panics GHC 6.4

Initial Comment:
Coming back to Haskell after a year off, I accidentally typed a very 
simple class definition wrong, and turns out that GHC 6.4 dies with 

ghc-6.4: panic! (the `impossible' happened, GHC version 6.4):
        ds_app_type Main.A{tc r1zQ} []

if you run

$ ghc crasher.hs
ghc-6.4: panic! (the `impossible' happened, GHC version 6.4):
        ds_app_type Main.A{tc r151} []

where crasher.hs is a file with a single line

class A where a :: A -> Int

I'm using the OSX version of GHC, by the way.

-carlos

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>Comment By: Simon Peyton Jones (simonpj)
Date: 2005-09-05 08:34

Message:
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Thanks Carlos.  I'm happy to say that this one was fixed a 
while ago, and will be ok in 6.4.1.

Simon

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