Thank you for your contribution to GHC!

Please take a few moments to verify that your commits fulfill the following:

 * [ ] are either individually buildable or squashed
 * [ ] have commit messages which describe *what they do*
   (referring to [Notes][notes] and tickets using `#NNNN` syntax when
   appropriate)
 * [ ] have added source comments describing your change. For larger changes you
   likely should add a [Note][notes] and cross-reference it from the relevant
   places.
 * [ ] add a [testcase to the
   testsuite](https://gitlab.haskell.org/ghc/ghc/wikis/building/running-tests/adding).

If you have any questions don't hesitate to open your merge request and inquire
in a comment. If your patch isn't quite done yet please do add prefix your MR
title with `WIP:`.

[notes]: https://gitlab.haskell.org/ghc/ghc/wikis/commentary/coding-style#comments-in-the-source-code