Another case of SpecConstr not specialising

Compile with -O2 -fno-spec-constr-count -fno-spec-constr-threshold:

foo :: Int -> Int -> Int -> (Int,Int)
foo !a !b !c = loop (Left (a,b))
  where
    loop :: Either (Int,Int) (Int, (Int,Int)) -> (Int,Int)
    loop (Left (!x,!n))
      | n > 0     = loop (Right (x,(x+c,n-1)))
      | otherwise = (x,n)

    loop (Right (i,t))
      | i < c     = loop (Right (i+1,t))
      | otherwise = loop (Left t)

!SpecConstr doesn't specialise for the (Int,Int) pair. Unless I'm mistaken, the !SpecConstr loop should get this since the call in foo has the form Left (I# x, I# y) and the pair then gets threaded through the loop.

Trac metadata

Trac field	Value
Version	7.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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