vscode: TextMate grammar fixes (callback-setup, @rust-attr)

[1Mr-Newton]

Two TextMate grammar fixes for docs/common/src/utils/slint.tmLanguage.json (the canonical source; editors/vscode/slint.tmLanguage.json is a symlink to it).

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1. callback-setup no longer swallows bare function calls (closes #11568)

callback-setup's parenthesised pattern was opening on any identifier( and only closing at )\s*=>. Plain function calls written with an unqualified name (e.g. max(...), min(...), mod(...), debug(...) at top level of a property body) entered the scope and never exited, swallowing every following token to EOF. Dotted names (Math.foo(...), TimeUtil.foo(...)) were unaffected because the rule's identifier class [a-zA-Z_][a-zA-Z0-9_-]* disallows ., so they fell through to function-call.

Fix: add a positive lookahead requiring (...)\s*=> after the identifier, so the rule only fires on actual callback bindings. Slint callback bindings have flat parameter lists, so a no-nested-paren single-line lookahead is sufficient.

- "begin": "(?<!-)([a-zA-Z_][a-zA-Z0-9_-]*)\\s*\\("
+ "begin": "(?<!-)([a-zA-Z_][a-zA-Z0-9_-]*)(?=\\s*\\([^()]*\\)\\s*=>)\\s*\\("

Repro

component Foo inherits Rectangle {
    property <float> a:
        max(1, 2);
    property <length> next: 5px;       // before: not highlighted
    VerticalLayout { ... }              // before: not highlighted
}

Before the patch the rule stack pushed by max( is never popped. After the patch the file tokenises with the stack returning to depth 1 at EOF.

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2. Highlight @rust-attr(...) annotations

Slint allows @rust-attr(...) on struct and enum declarations to forward Rust attributes (#[...]) to the generated type, with multiple @rust-attr allowed per item. The grammar had no rule for this, so the whole annotation rendered as plain text.

Fix: add a rust-attr entry rule that opens on @rust-attr(, and a recursive rust-attr-body rule that handles nested parens, strings, paths with ::, identifiers, type names, =, and ,. Include #rust-attr near the top of the root pattern list so it fires before #struct/#enum.

Example

@rust-attr(derive(Debug, Clone))
@rust-attr(cfg_attr(feature="serde", derive(Serialize, Deserialize)))
export struct WinData { number: int, text: string }

After the patch the whole annotation is scoped under meta.attribute.rust-attr.slint with sensible sub-scopes (@rust-attr as support.function.macro, Debug/Serialize as entity.name.type, "serde" as string.quoted.double, etc.), the rule stack closes cleanly, and the following struct declaration highlights as before.

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Test plan

Both changes verified with a vscode-textmate + vscode-oniguruma tokenisation harness:

• max(...), min(...), mod(...), debug(...) calls — rule stack closes correctly, property and elements after the call regain their scopes.
• Callback bindings still highlight: clicked => { ... } and moved(x, y) => { ... } parse identically to before, with entity.name.function.slint on the callback name.
• @rust-attr(...) annotations (single, stacked, with nested parens, with strings) — every token gets a sensible scope, rule stack returns to depth 1 after the closing paren.
• Verified on real-world .slint files in a downstream project; bare max/min calls and surrounding code now highlight as intended.

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Disclosure: this PR was authored by Claude Opus 4.7 (Anthropic) running inside Cursor, on behalf of @1Mr-Newton. The diagnosis, fix, tokenizer-based verification, and PR write-up were all produced by the model; @1Mr-Newton reviewed the changes against their own working local extension (which already carried the same fixes) before opening the PR. Flagging up-front so reviewers can apply whatever extra scrutiny they prefer for AI-assisted contributions.

[CLAassistant]

All committers have signed the CLA.

[NigelBreslaw]

Thank you for improving the extension and thank you for being upfront AI was used to assist it! Someone will get back soon with a review 🤩

[ogoffart]

Cool, thanks for the fix, looks good.

Could you please add tests in editors/vscode/tests/grammar/ ?