id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
3822,guards in arrow notation (Arrows extension) case statement cause compiler panic,StephenBlackheath,ross,"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.",bug,closed,high,7.0.1,Compiler,6.12.1,fixed,arrows guards case panic,,Unknown/Multiple,Unknown/Multiple,Compile-time crash,,T3822,,,