Rename plugin doesn't work with NamedFieldPuns

[santiweight]

The environment doesn't matter here: just a plugin bug...

Steps to reproduce

Rename the following field to something else using the rename plugin

{-# LANGUAGE NamedFieldPuns #-}
newtype Foo = Foo { field :: Int }

unFoo :: Foo -> Int
unFoo Foo{field} = field

Expected behaviour

I think the best UX should be that renames compose with bindings incurred by NamedFieldPuns

Actual behaviour

The output is instead:

{-# LANGUAGE NamedFieldPuns #-}
newtype Foo = Foo { bleh :: Int }

unFoo :: Foo -> Int
unFoo Foo{bleh} = field

i.e. the field reference in the binding site is renamed, but not the subsequent reference on the RHS of unFoo

[santiweight]

I'm happy to take this on, but it's not immediately clear to me what the solution is. The result returned from hie-db is a RefRow, which appears only to be a location and the OccName.

I see two options:

1. Have NamedFieldPuns return the RHS reference to field as a reference to field. I don't think this is a good solution, because I don't think the RHS reference is a reference to the field; it's more a reference to the punned field binding.
2. Do a subsequent pass for each punned field binding. In other words, if RefRow returned information about whether this reference is a punned field, then we could do a second pass on these punned fields.

I'm happy to take this on: someone more hie-savvy please tell me the preferable option (or some other option I didn't think/know of)

[July541]

Same as #2915?

[michaelpj]

cc @OliverMadine

[OliverMadine]

Sorry for the delay in following up on this.
This is a different issue to  #2915. I will open a PR shortly.