Core Lint error with LambdaCase

When I say

{-# LANGUAGE LambdaCase, TypeFamilies #-}

type family F a where
  F a = Bool -> a

foo = (\case True -> 5
             False -> 6) :: F Int

-dcore-lint tells me

*** Core Lint errors : in result of Desugar (after optimization) ***
/Users/rae/temp/Bug.hs:6:1: Warning:
    [RHS of foo :: Bool -> Int]
    From-type of Cast differs from type of enclosed expression
...

The problem is a missing mkTcSymCo in the relevant bit of tcExpr.

Will fix in ongoing work.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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