Semantic highlighting for function exit points

[lnicola]

As seen in IntelliJ

[matklad]

Yessss I want this a lot. The problem is, I don't see an LSP request we can use for it :0(

Maybe abuse document highlight?

[matklad]

[matklad]

https://microsoft.github.io/language-server-protocol/specification#textDocument_documentHighlight

[kjeremy]

That takes in a position though. You couldn't do this with semantic highlighting and token modifiers?

[matklad]

@kjeremy that's exatcly the UI -- higlights of all exit points activates when you are on a single exit point (and probably it makes sense to trigger it on return type as well).

[matklad]

For the refrece, IntellijJ impl is here: https://github.com/intellij-rust/intellij-rust/blob/master/src/main/kotlin/org/rust/ide/highlight/RsHighlightExitPointsHandlerFactory.kt

[kjeremy]

Ah! I thought it was always active. This would be really nice to have.

[woody77]

always active is definitely doable, but it can't be themed as a background change (but could be given bold or other font styling).

In the theme that I'm working on, making the ? operator extra clear is one of my goals (as well as other subtle, easy-to-miss things).

[kjeremy]

I think we could just use DocumentHIghlightKind::Text for this