Orientation of given `Coercible` constraints

Prelude> :m + GHC.Exts
Prelude GHC.Exts> let f :: Coercible a b => b -> a ; f = coerce

<interactive>:3:40:
    Could not coerce from ‛b’ to ‛a’
      because ‛b’ and ‛a’ are different types.
      arising from a use of ‛coerce’
    from the context (Coercible a b)
      bound by the type signature for f :: Coercible a b => b -> a
      at <interactive>:3:10-32
    In the expression: coerce
    In an equation for ‛f’: f = coerce

Something better could be done here (but its not clear what exactly, and to what general extend).

Trac metadata

Trac field	Value
Version	7.6.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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