Add tree-sitter-fe grammar to monorepo#1264
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micahscopes merged 9 commits intoargotorg:masterfrom Feb 21, 2026
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Consolidates the tree-sitter grammar (previously in a separate repo) into the main Fe repository for easier maintenance and testing.
Move tree-sitter-fe grammar into crates/ as a workspace member. Add dir-test driven integration tests to the parser crate that parse all existing .fe fixtures (syntax nodes, formatter, core/std ingots) with tree-sitter and assert no ERROR nodes. Fix unsafe extern block for edition 2024 compatibility. 92 of 117 fixtures pass; failures are expected on files using ref/own/mut syntax not yet supported by the grammar.
Grammar fixes:
- Add labeled parameter support (from sender: address)
- Add mode_type (ref/mut/own type prefixes) and mode_expression
- Add mode prefix in call_arg for (mut x) arguments
- Extend scoped_path with generic args on path segments (Foo<T>::method)
- Fix nested record/path_tuple patterns in record_pattern_field
- Add pattern bindings in recv_arm_pattern
- Fix scanner < disambiguation: track paren/bracket/brace depth,
reject ||/&&/=>/.. as generic markers, handle << for nested
qualified paths, distinguish { block bodies from {expr} const generics
Build system:
- Auto-run tree-sitter generate when grammar.js is newer than parser.c
- Always optimize parser.c at -O2 (96K-line state machine is unusable
at -O0 in debug builds)
Tests:
- Split into strict test (110 files, must be 100%) and coverage test
(363 files, regression threshold at 83%)
- Coverage spans syntax_node, fmt, core/std ingots, fe_test, cli_output,
and all uitest fixture suites
- Exclude intentionally broken files (parse_error.fe) and standalone
pattern fragments (pats/)
- Support combined receiver modes (`mut own self`, `mut ref self`)
- Make mode expressions bare prefix operators instead of requiring parens
- Add mut_pattern for mutable bindings in patterns (`Some(mut t)`)
- Support qualified paths in recv arm patterns and record pattern fields
- Add attribute call expressions (`#[selector = sol("...")]`)
- Support generic args in uses clauses (`uses Storage<T>`) and with params
- Remove redundant mode-prefixed call_arg variant (handled by mode_expression)
Raises coverage test pass rate from 87% to threshold-passing levels.
Strict test (110 files) still passes at 100%.
Unary + is a real Fe operator (prefix binding power 145 in the native parser). Naively adding it conflicted with + as the type bound separator in where clauses — tree-sitter preferred unary + over continuing the bound list. Fix: make type_bound_list explicitly left-recursive with prec.right(UNARY+1) so the + continuation always wins over the unary interpretation. Both `+expr` and `T: A + B + C` now parse correctly.
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2 tasks
The scanner stopped searching for a matching '>' after 256 characters, causing valid generic argument lists longer than that to be mistokenized as COMPARISON_LT. Remove the cap so disambiguation runs to completion.
Collapses parser.c, grammar.json, and node-types.json in GitHub diffs.
Use println! for cargo:warning= directives in build.rs (Cargo reads build script directives from stdout, not stderr). Allow print_stderr clippy lint in tree-sitter parse test file for progress output.
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@g-r-a-n-t this should be ready for review now |
g-r-a-n-t
approved these changes
Feb 21, 2026
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Summary
crates/tree-sitter-fe, consolidated from the standalone repo for easier co-maintenance with the compilerscanner.c) for<disambiguation (generics vs comparison), automatic semicolons, and method chainingcrates/parserthat parse all.fefixtures with tree-sitter: a strict suite (110 files, 100% pass) and a coverage regression suite (363 files)Test plan
cargo test -p parserpasses (tree-sitter fixture parse tests)cargo build -p tree-sitter-fesucceedscrates/tree-sitter-fepath