fix: detect Dart local variable shadowing a class field, in both engines

[carlos-alm]

Summary

The #2319 second follow-up (PR #2477) only detected a shadowing parameter, explicitly scoping out a shadowing local variable declaration (#2478) as needing more design work — a parameter is trivially in scope for the whole function body, but a local variable's scope is block-bounded and position-dependent.

Rather than leaving this deferred, I worked through a design that avoids the hard part (full control-flow-order reasoning, or relying on any assumption about whether Dart's compiler itself rejects a forward reference) by checking ordering and block-scope directly from the tree:

findEnclosingDartShadowingLocalName / find_enclosing_dart_shadowing_local_name walks up from the call site one enclosing block at a time, stopping at the function_body boundary. At each level, only that block's siblings before the entry statement's own index are checked for a matching local_variable_declaration — a local declared later in the same block is not yet in scope there, and one declared in a different branch of an if/for lives in a sibling block this walk never visits at all, so it can't falsely match either.

Confirmed via parse dumps (both engines) that this produces the identical block / local_variable_declaration / initialized_variable_definition AST shape for this scenario, so the fix mirrors 1:1 between findDartSelectorReceiver (TS) and handle_dart_call_expression + the legacy find_dart_selector_receiver (Rust, kept mirrored per this file's own convention even though it's currently dead code for the pinned grammar).

Two pre-existing tests (sets_receiver_on_a_local_variable_method_call / sets receiver on a local-variable method call) asserted the old, less-precise this.-prefixed behavior for a bare local — updated both to the new, correct bare-receiver behavior, since this is a genuine improvement these tests' own comments already flagged as imprecise ("the extractor cannot tell the two apart... prefixing is harmless here").

Test plan

• New Rust unit tests in dart.rs (local_variable_shadows_field module) — basic shadow, sibling-method no-shadow, sibling-block no-shadow, nested-block shadow, before-declaration no-shadow, end-to-end type resolution
• New TS unit tests in tests/parsers/dart.test.ts (#2478 describe block) — same coverage, WASM engine
• New dual-engine integration test tests/integration/issue-2478-dart-local-var-shadows-field.test.ts — mirrors issue-2319-dart-parameter-shadows-field.test.ts's exact pattern (same-named method on both types, confirms the call edge targets the local's type, never the field's)
• Updated 2 pre-existing tests whose old assertions described the now-fixed imprecise behavior
• Revert-verified: disabling each side's fix reproduces the pre-fix failures for every new test, including the integration test on both engines
• npx tsc --noEmit -p ., npm run lint, full npm test (5485 passed)
• cargo fmt -- --check, cargo clippy --lib -- -D warnings, cargo test --lib (1122 passed)

Closes #2478

[greptile-apps]

Greptile Summary

The PR updates both Dart extraction engines to distinguish a block-scoped local variable from a same-named class field when extracting method-call receivers.

• Walks preceding declarations across enclosing blocks while respecting declaration order and block boundaries.
• Mirrors the receiver-classification logic in the TypeScript/WASM and Rust/native extractors.
• Adds parser, native unit, and dual-engine integration coverage for shadowing, nested scopes, sibling scopes, declaration order, and end-to-end call resolution.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete actionable defects established in the changed paths.

The mirrored extractors apply the same block- and order-aware receiver classification, and the new tests cover the primary scope transitions and end-to-end resolution behavior.

Important Files Changed

Filename	Overview
crates/codegraph-core/src/extractors/dart.rs	Adds the native Dart block- and order-aware local-shadowing lookup, integrates it into both receiver paths, and adds focused unit coverage.
src/extractors/dart.ts	Adds the mirrored WASM extractor lookup and uses it to emit bare receivers for recognized shadowing locals.
tests/integration/issue-2478-dart-local-var-shadows-field.test.ts	Verifies both engines resolve a shadowed receiver to the local variable’s type and never to the field’s type.
tests/parsers/dart.test.ts	Adds WASM parser coverage for declaration order, nested and sibling blocks, method boundaries, and receiver/type-map output.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  Call["Dart receiver call: name.method()"] --> Param{"Same-named parameter?"}
  Param -->|Yes| Bare["Emit bare receiver: name"]
  Param -->|No| Local{"Earlier matching local in an enclosing block?"}
  Local -->|Yes| Bare
  Local -->|No| Field["Emit field receiver: this.name"]
  Bare --> LocalType["Resolve function-scoped local type"]
  Field --> FieldType["Resolve class-scoped field type"]

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[github-actions]

Codegraph Impact Analysis

2 functions changed → 4 callers affected across 1 files

• findEnclosingDartShadowingLocalName in src/extractors/dart.ts:664 (3 transitive callers)
• findDartSelectorReceiver in src/extractors/dart.ts:1117 (3 transitive callers)