Using overloaded syntax to avoid `base` dependency (RE: Marking ParsedModule fragments as non-user-originating)

[ÉRDI Gergő]

On Fri, 16 Jul 2021, Simon Peyton Jones via ghc-devs wrote:

> Yes, it would be much better to use the extension field.  That would stop the
> (GHC-independent) Language.Haskell.Syntax needing to talk about “witnesses”.

Here it is: https://gitlab.haskell.org/ghc/ghc/-/issues/20151