react-doctor/no-did-mount-set-state

Derive state in getDerivedStateFromProps or initial state instead of calling this.setState in componentDidMount, which forces an extra render.

Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires on a this.setState(...) call (callee object must be this, property named exactly setState) located directly inside a componentDidMount method or class field: including calls wrapped in a single if block or ternary: but only when that lifecycle method lives inside a genuine React component: an ES5 createReactClass(...)/React.createReactClass(...) call, or an ES6 class extending Component/PureComponent/React.Component/React.PureComponent. In the default "allowed" mode, a setState buried two or more functions deep (inside a setTimeout, Promise.then, or a callback/inner function passed elsewhere) does NOT fire; only "disallow-in-func" mode flags those. A plain function or non-React class with a method named componentDidMount is NOT flagged, because detection requires that enclosing createReactClass(...) call or React-base-class extension: so the valid fixture function Hello() { this.setState(...) } does not trigger.

Evidence boundary

The diagnostic proves only that the detector’s modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, repository policy, exceptions, and required rendered or runtime evidence before deciding the occurrence.

Record one outcome:

• Confirmed failure: The required evidence establishes the violation.
• Rejected: A documented exception or false-positive predicate applies.
• Needs evidence: Named evidence can still be collected.
• Unavailable: Required evidence cannot be collected in this run.
• Waived with evidence: An authorized, scoped exception applies to an established failure.
• Observation: The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review condition. It is not a pass or false positive.

Default severity is registry metadata. Use the occurrence’s JSON severity after repository configuration when ordering real findings.

Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

If the value is available from initial props, initialize it in the constructor/class-field state or derive it directly during render; do not add getDerivedStateFromProps merely to mirror props. Keep a guarded componentDidMount update when the value inherently requires a committed DOM node, subscription, or asynchronous result, and update at the point that result actually arrives. Preserve timing and behavior rather than moving the call into a callback only to evade the detector. See https://oxc.rs/docs/guide/usage/linter/rules/react/no-did-mount-set-state

Repository-wide copy prompt

Use this repository-wide prompt only after validating each occurrence. For one occurrence, use the guidance above.