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  • Glasgow Haskell CompilerGlasgow Haskell Compiler
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  • #5691
Closed
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Issue created Dec 12, 2011 by dominiquedevriese@trac-dominiquedevriese

Crash: strange interaction of ScopedTypeVariables extension with type class name resolution

I saw a compiler crash ("the 'impossible' happened..."), seemingly caused by a strange interaction of the ScopedTypeVariables GHC extension with type class name resolution. I am attaching a cut-down example showing the crash. I hope this helps to find the bug. I have only tested with GHC 7.0.4; I am not sure if it is still present in later versions of the compiler. The crash occurs when I load the file in GHCi and evaluate the code

parseRD (pure_ 'a') "a"

or when I simply try to compile the file from the command line.

Trac metadata
Trac field Value
Version 7.0.4
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Type checker)
Test case
Differential revisions
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