Poor error message for Coercible constraint unsatisfiability

If I say

import Data.Coerce

foo = coerce

I get

    Couldn't match representation of type ‘a0’ with that of ‘b0’
      ‘a0’ is untouchable
        inside the constraints: ()
        bound by the inferred type of foo :: a0 -> b0
        at /Users/rae/temp/bug/App.hs:3:1-12
    Relevant bindings include
      foo :: a0 -> b0 (bound at /Users/rae/temp/bug/App.hs:3:1)
    In the expression: coerce
    In an equation for ‘foo’: foo = coerce

How awful. Eta-expanding foo works fine, though.

Trac metadata

Trac field	Value
Version	7.11
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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