#3822: pattern guards in arrow notation (Arrows extension) case statement cause
compiler panic
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Reporter: StephenBlackheath | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.12.1 | Keywords: arrows pattern guards case
panic
Os: Linux | Testcase: patternGuard.hs
Architecture: x86_64 (amd64) | Failure: Compile-time crash
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The attached test case causes this panic message:
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ghc: panic! (the 'impossible' happened)
(GHC version 6.12.1 for x86_64-unknown-linux):
initC: srt_lbl
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
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The offending line is the one with '| neg'. It doesn't panic if you use
the commented out line below it instead.
This kind of case statement is specific to arrow notation (provided by the
Arrows extension) - the compiler uses ArrowChoice to implement it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3822>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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