Add parameterLabel modifier for argument labels in semantic tokens

[PhantomInTheWire]

Motivation: Argument labels are currently tokenized as function without any modifier, making them indistinguishable from function names. This prevents theme authors from styling them differently, particularly important for accessibility (e.g., themes for neurodivergent developers) and personal preference.

Changes:

• Added parameterLabel semantic token modifier to SemanticTokenModifiers extension
• Applied the modifier to argument labels in both the syntactic path (SemanticTokens.swift) and semantic path (SyntaxHighlightingTokenParser.swift) to ensure consistency.
• Updated the token legend to include the new modifier so editors can decode it.
• Updated all(?) relevant test expectations to include .parameterLabel for argument label tokens.

Fixes #1540

[ahoppen]

Nice. Looks good to me, I’d just like to define the modifier in swift-tools-protocols.

[PhantomInTheWire]

@ahoppen i have a open pr on swift-tools-protocols for this. we will have to merge that first. swiftlang/swift-tools-protocols#31 before this

[ahoppen]

Thanks for the PR to swift-tools-protocols. We will need @owenv’s help to tag a new release of swift-tools-protocols and get it into the CI pipeline and he’s on vacation until the new year. Let’s get this over the finish line when he’s back.

[PhantomInTheWire]

hey @ahoppen @owenv i think we should be able to tag a new release now, lmk if some changes are needed from my end.

[ahoppen]

@owenv is already on it. https://github.com/swiftlang/swift-tools-protocols/releases/tag/0.0.10 has just been tagged and we now need to update the toolchain builds to use that tag so we can land this PR.

[PhantomInTheWire]

@ahoppen so do i have to open a separate pr to bump swift-tools-protocols to 0.0.10 in package.swift? i noticed its one of the only ones that is tagged to a version and not directly to main

[ahoppen]

We have #2425 for that. We also need to bump the version in other repos at the same time plus some additional manual work in CI jobs. I’ll let you know once the version has been updated and we can proceed with this PR. Sorry for the delay.

[PhantomInTheWire]

Thanks for the update, appreciate you handling the coordination. I’m not in a rush, happy to wait until the version bumps land.