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  • Glasgow Haskell Compiler
  • GHCGHC
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  • #845
Closed
Open
Created Aug 04, 2006 by Jason McCarty <jmccarty@sent.com>@trac-jmccarty

irrefutable pattern matching on unboxed tuple causes panic

Compiling the following program with -fglasgow-exts

main = case (# (), () #) of ~(# _, _ #) -> return ()

causes GHC to fail with the message

ghc-6.4.2: panic! (the `impossible' happened, GHC version 6.4.2):

dsLExpr: tuple pattern: return @ () GHC.Base.()

The equivalent (I think) expression

main = let (# _, _ #) = (# (), () #) in return ()

compiles without complaint.

This is GHC version 6.4.2 on i386 Debian with a 2.6.17.6 Linux kernel. I didn't test with any other unboxed types.

Trac metadata
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Version 6.4.2
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler
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