haskell
Improving Handling of Structured Diagnostics
Most of HLS is now using GHC structured diagnostics instead of regexes (#4605). However, there are still some messages we still rely on regex matching for, because they aren't available in structured format. I've created a GHC issue, but I'm not sure if this is a complete list.
Known Instances
Here are the ones I know about:
Suggest Type Signature Change: We have to extract the declName from a type mismatch from the ErrInfo (an SDoc).
Fill typed holes: The hole fit and refinement suggestions are stored in ErrInfo supplementary.
Fill type wildcard: We need to determine whether the user wrote a top-level hole, for example whether the user wrote foo :: _ or foo :: Maybe _. We do this again, by looking at ErrInfo context.
Discussion
To move forward, we'll still need to
- Make sure the list above is complete
- Figure out specifically which fields we need to add
Related Links
https://github.com/haskell/haskell-language-server/issues/4605 https://gitlab.haskell.org/ghc/ghc/-/issues/26353
