API to represent dead / inactive code

[Trass3r]

Language plugins have to resort to custom LSP extensions to achieve a dimming effect for inactive code like in other IDEs:

I'd suggest adding an inactive or disabled SemanticTokenModifier and using it to style the code like in the picture.

The only question is how to make sure the whole line appears differently (iff the whole line is affected) and not just the portion of each inactive line covered by text, which may look weird.

[dbaeumer]

@alexdima I assign this for you for now. We had this discussion a while back ago and we purposely decided to not have this in semantic tokens because they are restraint to a work/token. The idea was that we have a separate request to compute these fade effects. Is this still the way to go from your point of view?

[alexdima]

👍 This has come up before, in this exact context of #ifdef pragmas, but also in the context of dead code (e.g. code after a return statement, code inside an if (false) {} block, etc.). We also thought that there might be more useful things to do with such inactive code regions than just render the text faded out, e.g. we could add options to fold these regions by default, to render the lines with a different brackground, etc.

I think we agreed that this does not fall under semantic tokens because such dead or inactive code could in certain cases get parsed by the compiler and could have semantic tokens independent of the fact that it is dead. I think we decided the best way forward is to add new special API in the future and until such new API is done to direct folks toward text editor decorations.

also cc @aeschli

[jrieken]

Outside of semantic highlight you can use DiagnosticTag.Unnecessary. The name is slightly misleading but the only thing it does is that it dims the code marked like that