Add inlay hint for `// endregion` marker that displays the value of `// region: label`

[ZylosLumen]

If there is a lot of code in between, it can be hard to tell what an // endregion marker refers to. One way is to copy paste the label but then you would need to keep it in sync whenever you update it (think about c++ namespace, ifdef, etc. ending comment markers)

Proposal: Add an inlay hint after // endregion markers that display the label.
Alternative: Provide goto definition for // endregion markers

[ChayimFriedman2]

Region folding is a feature of the editor, therefore IMO the editor should provide that hint, not rust-analyzer.

[ZylosLumen]

Region folding is a feature of the editor, therefore IMO the editor should provide that hint, not rust-analyzer.

I thought rust-analyzer handled that?
https://rust-analyzer.github.io/book/features.html#folding

Defines folding regions for curly braced blocks, runs of consecutive use, mod, const or static items, and region / endregion comment markers.

Ironically, the linked file includes the following:

#[derive(Debug, PartialEq, Eq)]
pub enum FoldKind {
    Comment,
    Imports,
    Region,
    Block,
    ArgList,
    Array,
    WhereClause,
    ReturnType,
    MatchArm,
    Function,
    // region: item runs
    Modules,
    Consts,
    Statics,
    TypeAliases,
    TraitAliases,
    ExternCrates,
    // endregion: item runs
}

[ChayimFriedman2]

Oh it seems indeed r-a is doing that.