Importing a newtype constructor can break typechecking

Summary

Having a newtype constructor in scope can cause a reduction stack overflow when the program would otherwise typecheck.

Steps to reproduce

The following comes from this StackOverflow answer by @kabuhr.

-- HyperFunction.hs
module HyperFunction where
newtype Hyper a b = Hyper { invoke :: Hyper b a -> b }

-- HyperCoerce.hs
module HyperCoerce where
import HyperFunction (Hyper)
-- The next line breaks it
-- import HyperFunction (Hyper (..))

import Data.Coerce
(#.) :: (Coercible c b) => q b c -> Hyper a b -> Hyper a c
(#.) _ = coerce

Compiling this as is works. Adding the commented line gives a reduction stack overflow.

Expected behavior

The modules compile.

Environment

• GHC version used: 8.6.3

Optional:

• Operating System:
• System Architecture: