fix(react-doctor): honor empty-frame barriers in no-prop-callback-in-effect / no-derived-useState prop-stack lookups

[aidenybai]

Surfaced during a self-review of the in-flight useEffect rule PRs (#153, #154, #155, #156, #157, #162). The bug is on main and predates that work, but the same shape needed fixing on the new branches too — fixing here keeps main honest and avoids forking the convention.

The bug

The visitor scaffolding shared by no-prop-callback-in-effect and no-derived-useState pushes an empty Set when entering a non-component FunctionDeclaration / ArrowFunctionExpression. The intent (per the existing comment) is to act as a barrier: identifiers inside a helper shouldn't resolve against an outer component's props because a closed-over value is not a prop of the helper.

The implementation walked the entire stack anyway:

const isPropName = (name: string): boolean => {
  for (let stackIndex = componentPropParamStack.length - 1; stackIndex >= 0; stackIndex--) {
    if (componentPropParamStack[stackIndex].has(name)) return true;
  }
  return false;
};

Top frame is empty → keep walking → next frame matches → return true. Barrier intent broken.

False positives this produced

Both rules incorrectly fired on this shape:

function Outer({ value, onChange }) {
  function inner() {
    const [draft, setDraft] = useState(value);          // FP: no-derived-useState
    useEffect(() => {
      onChange(isOn);
    }, [isOn, onChange]);                               // FP: no-prop-callback-in-effect
  }
  inner();
}

value and onChange are lexically captured from Outer, not props of inner.

Fix

Single-line change in each rule's isPropName: stop the walk at the first empty frame.

const isPropName = (name: string): boolean => {
  for (let stackIndex = componentPropParamStack.length - 1; stackIndex >= 0; stackIndex--) {
    const frame = componentPropParamStack[stackIndex];
    if (frame.size === 0) return false;   // ← barrier
    if (frame.has(name)) return true;
  }
  return false;
};

The empty frame the visitor pushes when entering a non-component function now acts as the barrier the comment claims it does.

Tests

New file tests/regressions/prop-stack-barrier.test.ts with 4 cases:

• no-derived-useState real prop → still flags ✅
• no-derived-useState nested helper closing over outer prop → no longer flags ❌
• no-prop-callback-in-effect real prop → still flags ✅
• no-prop-callback-in-effect nested helper closing over outer prop → no longer flags ❌

484/484 tests passing. Lint, typecheck, format clean. No changeset.

Related

The same fix has been applied to the equivalent helpers introduced by the in-flight rule PRs:

• feat: comprehensive useEffect analyzer expansion (3 rules + 2 extensions) #157 no-mirror-prop-effect (commit 6954c64 on cursor/comprehensive-useeffect-analyzer-7144)
• feat: add prefer-use-effect-event rule #162 prefer-use-effect-event (commit 77be9a8 on cursor/prefer-use-effect-event-7144)

Both of those branches additionally switched from walkAst to a direct for (statement of componentBody.body) iteration so they only visit useEffects that are direct top-level statements — that's a separate fix for a related FP path that only affected the new rules.

  

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Project	Deployment	Actions	Updated (UTC)
react-doctor-website	Ready	Preview, Comment	May 7, 2026 9:59pm