Calling Fourmolu via HLS infers wrong fixities

[RobinStoll]

When using Fourmolu as a formatter via HLS, it infers different fixities of binary operators than when calling Fourmolu directly via the command line. This happens regardless of whether HLS uses its built-in Fourmolu or calls an external one.

It happened with the following operators:

• ^. from lens
• ## from map-syntax
• .: from digestive-functors

It is relatively easy to circumvent by specifying these fixities explicitly in fourmolu.yaml, but it is still a little annoying. It also took me a while to figure out why it was behaving differently.

Your environment

Which OS do you use?
openSUSE
Which LSP client (editor/plugin) do you use?
VS Code & Haskell extension
Which version of HLS do you use and how did you install it?
1.8.0.0 via ghcup via VS Code Haskell extension
Have you configured HLS in any way (especially: a hie.yaml file)?
Only via VS Code

[georgefst]

See #3454.

Getting these working for non-CLI mode may require some upstream refactoring to expose the right functionality, similarly to #3449.