Add code action to suppress specific hlint warnings

[srid]

I'm using VSCode + HLS 0.6.0.

I'd like to permanently disable certain hlint suggestions, such as the "Suggestion: Use camelCase" on ADTs. On a per-project basis, if possible.

It would be nice if there was an extra code action to disable the specific hlint. So we would see the list as:

• Apply hint: ...
• Apply all hints
• Ignore this hint: ...

If the user selects "Ignore this hint", then the project's .hlint.yaml would be updated accordingly.

[Anrock]

Some related discussion in #571 and per-file supression in haskell/ghcide#897

[jneira]

@srid
Hi, this is a sensible feature. However implement at project level will be harder than a module level:

• We have to locate o create .hlint.yaml and update in a reliable way (it canbe trickier that it sounds)
• At module level we only should add a directive in the source of the module at hand (similar to the languages pragmas we are already adding)

So i think we could start with Ignore this hint: ... in the module (that can be useful too) and add the project afterwards

I think implememt it at module level would not be terribly difficult 😄

[SeungheonOh]

In addition, it would be useful to suppress hint on specific line by, for example, using commenting at the end of the line.

[ndmitchell]

HLint doesn't have a way to supress hints by line, only by definition. However, if you don't like a hint, I'd usually just ignore it for the whole module unless you find that hint gives a lot of value elsewhere in the module - and they are hints, so are usually nice to have at best. It's also much easier from an HLS perspective to just put the pragma at the top of the file.