Panic in rejigConRes

When I compile the following erroneous code

{-# LANGUAGE DataKinds, TypeFamilies, GADTs #-}

import GHC.TypeLits

data Foo = Bar

data instance Sing (n :: Foo) where
  SBar :: Sing Foo

I get

*** Exception: compiler/typecheck/TcTyClsDecls.lhs:1266:5-62: Irrefutable pattern failed for pattern Data.Maybe.Just subst

I think this is my fault. I will fix.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture