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case expression with mixed use of Num instances cause spurious overlap warning

    • Closed Issue created by bscarlet @trac-bscarlet 
    newtype Whomp = Whomp Int
  deriving (Eq)

instance Num Whomp where
  Whomp a + Whomp b = Whomp (a+b)
  Whomp a * Whomp b = Whomp (a*b)
  abs (Whomp a) = Whomp (abs a)
  signum (Whomp a) = Whomp (signum a)
  fromInteger = Whomp . fromInteger

foo :: Whomp -> String
foo cc = case cc of
    Whomp 0 -> "zero"
    10 -> "ten"

    produces

    Foo.hs:12:10: Warning:
    Pattern match(es) are overlapped
    In a case alternative: Whomp 0 -> ...
    Trac metadata
    Trac field Value
    Version 7.6.3
    Type Bug
    TypeOfFailure OtherFailure
    Priority normal
    Resolution Unresolved
    Component Compiler
    Test case
    Differential revisions
    BlockedBy
    Related
    Blocking
    CC
    Operating system
    Architecture
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