id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
1759,HPC interaction with -Wall leading to spurious pattern match warnings,guest,igloo,"Without -fhpc, the following program passes the pattern match checker:

{{{
f :: String -> Int
f x | null x    = 1
    | otherwise = 2


main :: IO ()
main = print $ f []
}}}

However, with -fhpc on, we get the spurious warning:

{{{
    A.hs:3:0:
        Warning: Pattern match(es) are non-exhaustive
                 In the definition of `f': Patterns not matched: _
}}}

Causing libraries using -Werror to fail to build when using -fhpc.
}}}

-- Don ",merge,closed,low,,Compiler,6.8,fixed,HPC,dons@…,Unknown/Multiple,Unknown/Multiple,,Unknown,,,,