Use builtin scopes more

[georgewfraser]

VSCode has added more builtin fallback scopes, so we can remove some of our fallback scopes by aligning with their conventions.

Note that the macro scope doesn't seem to actually work at the moment. I have filed a bug with VSCode: microsoft/vscode#110150

[matklad]

Wait, did they ship nested.types in LSP/VS Code? I thought that that's only planned?

Or does it work by some coincidence, where VS Code uses textmate scope for this semantic token, without anything establishing the mapping explicitly?

[georgewfraser]

Hmmm. I didn't think about this, I wonder if I should really be adding an attribute "defaultLibrary" rather than sending both "type" and "defaultLibrary" in one token "type.defaultLibrary".

[matklad]

Ah, yeah, indeed, it is standard token modifier: https://code.visualstudio.com/api/language-extensions/semantic-highlight-guide#semantic-token-classification

SO, I think when we lower BUITIN_TYPE to lsp, we should snap this builtin modifier on top (there's a chance that lsp_types even has it as a constant)

[matklad]

Hm, I guess this is "practicality beats purity"? const & readonly are pretty different things, but I guess we can re-purpose readonly as const and just use mutable for (complement of) cases where we'd use readonly otherwise?

[georgewfraser]

I think this is debatable. It's not like we can match the builtin scopes 100%, and constant is more semantically correct, so we could just decide to do our own thing. It does seem like the builtins are basically "whatever typescript needs."

[matklad]

I am inclined to stick to semantically-correct constant, unless readonly significantly improves theme support.

[georgewfraser]

OK, I've cut this down to just remove the macro fallback, now that VSCode has implemented a builtin fallback: microsoft/vscode#110150

[matklad]

Ah, perfect!

bors r+

[bors]

Build succeeded:

• Rust (macos-latest)
• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)