tree-sitter: fix type<T>; parse failure in type position

[borisbat]

Summary

Reported via Telegram (user Vi): Zed syntax highlighting breaks on type<…> used as a function parameter type, e.g.

def private get_type_id(t : type<auto(T)>) : int {
  print("{typeinfo typename(t)}")
  return -1
}

Root cause: the tree-sitter grammar only recognized type<T> in two places — inside _type_macro_arg (the inner sequence of a padded(type<T>, …) macro call) and as type_expression (which appears in expression positions only). Function parameters, return types, and struct fields declared with type<T> therefore fragmented the parse — even though this is the canonical witness-parameter form used throughout daslib (e.g. daslib/clargs.das lines 239/246/263/278/289).

Bison reference: type_declaration_no_options_no_dim → DAS_TYPE '<' type_declaration '>' (ds2_parser.ypp:3281).

Changes

• New type_witness rule mirroring the bison production, added to _type so it's accepted wherever a type is expected (parameters, return types, struct fields, typedefs, generic args, etc.).
• _type_macro_arg now reuses type_witness.
• type_expression stays — it remains the expression-context form (let x = type<int>); the conflict declaration is updated to [type_expression, type_witness].
• "type" @keyword in both queries/highlights.scm and zed-daslang/languages/daslang/highlights.scm already covers the keyword highlight globally; no query changes needed.

Tests

Five new corpus cases added to test/corpus/declarations.txt:

1. Basic param — def parse_int(t : type<int>)
2. Auto generic param — def get_type_id(t : type<auto(T)>) : int (the bug-report case)
3. Return type — def make_witness() : type<int>
4. Struct field — struct Foo { t : type<float> }
5. Nested — def foo(t : type<array<int>>)

tree-sitter test result: 34/34 pass (5 new + 29 prior, no regressions).

Notes on parser.c regen

The 0.22.0 CLI pinned in package.json doesn't run on Node 24 (EISDIR on drive root during grammar.js module resolution), so generation used 0.26.9 (still ABI 14). The parser.c diff is large because of the CLI version bump on top of the rule addition; grammar.json (+52/-26) and node-types.json (+22/-2) reflect only the rule change.

Test plan

• tree-sitter test (all 34 corpus cases pass)
• tree-sitter parse on the bug-report snippet produces (type_witness type: (auto_type (identifier))) correctly nested under function_argument
• tree-sitter parse on padded(type<int>, 16) in type position still produces (type_macro …) (existing path intact)
• tree-sitter parse on let x = type<int> still produces (type_expression …) (expression path intact)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes a tree-sitter parsing gap where type<...> (type-witness form) was only recognized in limited contexts, causing broken parses/highlighting when used in type positions like function parameters, return types, and struct fields.

Changes:

• Introduces a dedicated type_witness rule and includes it in _type so type<T> is accepted anywhere a type is expected.
• Reuses type_witness inside _type_macro_arg and updates the declared conflict to [type_expression, type_witness] to preserve expression-context type<...> parsing.
• Adds new corpus coverage for type-witness usage in parameter, return type, struct field, and nested generic-type cases.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
tree-sitter-daslang/grammar.js	Adds type_witness, wires it into _type and _type_macro_arg, and updates the conflict set vs type_expression.
tree-sitter-daslang/src/grammar.json	Regenerates the compiled grammar to include type_witness and the updated conflict declaration.
tree-sitter-daslang/src/node-types.json	Regenerates node metadata to add the type_witness node and adjust affected parent/child relationships.
tree-sitter-daslang/test/corpus/declarations.txt	Adds corpus cases verifying type<...> parses correctly in multiple type positions.

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