#3822: guards in arrow notation (Arrows extension) case statement cause compiler
panic
-----------------------------------------+----------------------------------
Reporter: StephenBlackheath | Owner: ross
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.1
Keywords: arrows guards case panic | Difficulty:
Os: Unknown/Multiple | Testcase: patternGuard.hs
Architecture: Unknown/Multiple | Failure: Compile-time crash
-----------------------------------------+----------------------------------
Description changed by igloo:
Old description:
> The attached test case causes this panic message:
>
> -----
> 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
> -----
>
> 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.
New description:
The attached test case causes this panic message:
{{{
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
}}}
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#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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