# `react-doctor/no-redundant-should-component-update`

Review shouldComponentUpdate overrides on PureComponent; deleting an override changes behavior unless it is proven equivalent to the inherited shallow comparison

- **Status:** Active
- **Category:** Architecture
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context
- **Default configuration:** Enabled
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** always
- **Requirements:** react
- **Priority:** 34 (P3)
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://oxc.rs/docs/guide/usage/linter/rules/react/no-redundant-should-component-update)

## Validation prompt

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

Fires when a class extends `PureComponent` (a bare identifier named `PureComponent` or the `React.PureComponent` member expression) and defines `shouldComponentUpdate`. The override replaces PureComponent's inherited implementation; it is not automatically redundant. Inspect the method body and callers to determine whether it intentionally performs a different comparison. Also confirm the superclass resolves to React PureComponent because matching is name-based.

## 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, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

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

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 or expiry condition. It is not a pass or false positive.

## Fix prompt

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

Preserve an intentional custom comparison and switch the base class to React.Component so the update policy is explicit. Delete shouldComponentUpdate only after proving it is equivalent to PureComponent's shallow prop and state comparison and focused tests cover skipped and accepted updates. Do not mechanically delete the override: doing so can change which renders occur. See https://react.dev/reference/react/PureComponent

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/no-redundant-should-component-update` diagnostic in the current repository.

Required change:
- Preserve an intentional custom comparison and switch the base class to React.Component so the update policy is explicit. Delete shouldComponentUpdate only after proving it is equivalent to PureComponent's shallow prop and state comparison and focused tests cover skipped and accepted updates. Do not mechanically delete the override: doing so can change which renders occur. See https://react.dev/reference/react/PureComponent.

Validation before editing:
Fires when a class extends `PureComponent` (a bare identifier named `PureComponent` or the `React.PureComponent` member expression) and defines `shouldComponentUpdate`. The override replaces PureComponent's inherited implementation; it is not automatically redundant. Inspect the method body and callers to determine whether it intentionally performs a different comparison. Also confirm the superclass resolves to React PureComponent because matching is name-based.

Constraints:
- Make the smallest change that fixes the root cause.
- Preserve behavior and interfaces unrelated to this diagnostic.
- Reuse existing project components, utilities, and conventions.
- Do not introduce render-phase side effects, render-phase state updates, or Hooks rule violations.
- Adapt identifiers and framework details instead of copying blindly.
- Do not disable the rule or suppress matching code.

Assessment:
- Record detector evidence, applicability facts, assumptions, missing evidence, and the rule class for this occurrence.
- Return one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
- A waiver records the established failure, scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

Verification:
- Run focused tests for the changed behavior.
- Run React Doctor and confirm this diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report the files changed and any checks you could not run.
````