functions on records with overloaded names can be given a too-specific type

Here's a reduced test-case showing a discrepancy between the symmetric functions foo and bar; the inferred type for foo is too specific.

data T a = A{ m1 :: a } | B{ m1, m2 :: a } | C{ m2 :: a }

-- bar :: (t -> a) -> T t -> T a
bar f x@(A m) = x{m1 = f m}

-- foo :: (a -> a) -> T a -> T a
foo f x@(C m) = x{m2 = f m}

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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