ValidateNoSetStateInRender.ts — react Source File

Source Code

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import {
  CompilerDiagnostic,
  CompilerError,
  ErrorCategory,
} from '../CompilerError';
import {HIRFunction, IdentifierId, isSetStateType} from '../HIR';
import {computeUnconditionalBlocks} from '../HIR/ComputeUnconditionalBlocks';
import {eachInstructionValueOperand} from '../HIR/visitors';
import {Result} from '../Utils/Result';

/**
 * Validates that the given function does not have an infinite update loop
 * caused by unconditionally calling setState during render. This validation
 * is conservative and cannot catch all cases of unconditional setState in
 * render, but avoids false positives. Examples of cases that are caught:
 *
 * ```javascript
 * // Direct call of setState:
 * const [state, setState] = useState(false);
 * setState(true);
 *
 * // Indirect via a function:
 * const [state, setState] = useState(false);
 * const setTrue = () => setState(true);
 * setTrue();
 * ```
 *
 * However, storing setState inside another value and accessing it is not yet
 * validated:
 *
 * ```
 * // false negative, not detected but will cause an infinite render loop
 * const [state, setState] = useState(false);
 * const x = [setState];
 * const y = x.pop();
 * y();
 * ```
 */
export function validateNoSetStateInRender(
  fn: HIRFunction,
): Result<void, CompilerError> {
  const unconditionalSetStateFunctions: Set<IdentifierId> = new Set();
  return validateNoSetStateInRenderImpl(fn, unconditionalSetStateFunctions);
}

function validateNoSetStateInRenderImpl(
  fn: HIRFunction,
  unconditionalSetStateFunctions: Set<IdentifierId>,
): Result<void, CompilerError> {
  const unconditionalBlocks = computeUnconditionalBlocks(fn);
  let activeManualMemoId: number | null = null;
  const errors = new CompilerError();
  for (const [, block] of fn.body.blocks) {
// ... (128 more lines)