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Author SHA1 Message Date
Lauren Tan
7b38acca0b [compiler][wip] Extend ValidateNoDerivedComputationsInEffects for props derived effects
This PR adds infra to disambiguate between two types of derived state in effects:
  1. State derived from props
  2. State derived from other state

TODO:
- [ ] Props tracking through destructuring and property access does not seem to be propagated correctly inside of Functions' instructions (or i might be misunderstanding how we track aliasing effects)
- [ ] compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/useEffect/invalid-derived-state-from-props-computed.js should be failing
- [ ] Handle "mixed" case where deps flow from at least one prop AND state. Should probably have a different error reason, to aid with categorization
2025-09-09 14:10:44 -07:00
7 changed files with 194 additions and 26 deletions

View File

@@ -13,14 +13,21 @@ import {
FunctionExpression,
HIRFunction,
IdentifierId,
Place,
isSetStateType,
isUseEffectHookType,
} from '../HIR';
import {printInstruction, printPlace} from '../HIR/PrintHIR';
import {
eachInstructionValueOperand,
eachTerminalOperand,
} from '../HIR/visitors';
type SetStateCall = {
loc: SourceLocation;
propsSource: Place | null; // null means state-derived, non-null means props-derived
};
/**
* Validates that useEffect is not used for derived computations which could/should
* be performed in render.
@@ -48,12 +55,96 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
const candidateDependencies: Map<IdentifierId, ArrayExpression> = new Map();
const functions: Map<IdentifierId, FunctionExpression> = new Map();
const locals: Map<IdentifierId, IdentifierId> = new Map();
const derivedFromProps: Map<IdentifierId, Place> = new Map();
const errors = new CompilerError();
if (fn.fnType === 'Hook') {
for (const param of fn.params) {
if (param.kind === 'Identifier') {
derivedFromProps.set(param.identifier.id, param);
}
}
} else if (fn.fnType === 'Component') {
const props = fn.params[0];
if (props != null && props.kind === 'Identifier') {
derivedFromProps.set(props.identifier.id, props);
}
}
for (const block of fn.body.blocks.values()) {
for (const instr of block.instructions) {
const {lvalue, value} = instr;
// Track props derivation through instruction effects
if (instr.effects != null) {
for (const effect of instr.effects) {
switch (effect.kind) {
case 'Assign':
case 'Alias':
case 'MaybeAlias':
case 'Capture': {
const source = derivedFromProps.get(effect.from.identifier.id);
if (source != null) {
derivedFromProps.set(effect.into.identifier.id, source);
}
break;
}
}
}
}
/**
* TODO: figure out why property access off of props does not create an Assign or Alias/Maybe
* Alias
*
* import {useEffect, useState} from 'react'
*
* function Component(props) {
* const [displayValue, setDisplayValue] = useState('');
*
* useEffect(() => {
* const computed = props.prefix + props.value + props.suffix;
* ^^^^^^^^^^^^ ^^^^^^^^^^^ ^^^^^^^^^^^^
* we want to track that these are from props
* setDisplayValue(computed);
* }, [props.prefix, props.value, props.suffix]);
*
* return <div>{displayValue}</div>;
* }
*/
if (value.kind === 'FunctionExpression') {
for (const [, block] of value.loweredFunc.func.body.blocks) {
for (const instr of block.instructions) {
if (instr.effects != null) {
console.group(printInstruction(instr));
for (const effect of instr.effects) {
console.log(effect);
switch (effect.kind) {
case 'Assign':
case 'Alias':
case 'MaybeAlias':
case 'Capture': {
const source = derivedFromProps.get(
effect.from.identifier.id,
);
if (source != null) {
derivedFromProps.set(effect.into.identifier.id, source);
}
break;
}
}
}
}
console.groupEnd();
}
}
}
for (const [, place] of derivedFromProps) {
console.log(printPlace(place));
}
if (value.kind === 'LoadLocal') {
locals.set(lvalue.identifier.id, value.place.identifier.id);
} else if (value.kind === 'ArrayExpression') {
@@ -97,6 +188,7 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
validateEffect(
effectFunction.loweredFunc.func,
dependencies,
derivedFromProps,
errors,
);
}
@@ -112,6 +204,7 @@ export function validateNoDerivedComputationsInEffects(fn: HIRFunction): void {
function validateEffect(
effectFunction: HIRFunction,
effectDeps: Array<IdentifierId>,
derivedFromProps: Map<IdentifierId, Place>,
errors: CompilerError,
): void {
for (const operand of effectFunction.context) {
@@ -119,16 +212,22 @@ function validateEffect(
continue;
} else if (effectDeps.find(dep => dep === operand.identifier.id) != null) {
continue;
} else if (derivedFromProps.has(operand.identifier.id)) {
continue;
} else {
// Captured something other than the effect dep or setState
console.log('early return 1');
return;
}
}
for (const dep of effectDeps) {
console.log({dep});
if (
effectFunction.context.find(operand => operand.identifier.id === dep) ==
null
null ||
derivedFromProps.has(dep) === false
) {
console.log('early return 2');
// effect dep wasn't actually used in the function
return;
}
@@ -136,11 +235,18 @@ function validateEffect(
const seenBlocks: Set<BlockId> = new Set();
const values: Map<IdentifierId, Array<IdentifierId>> = new Map();
const effectDerivedFromProps: Map<IdentifierId, Place> = new Map();
for (const dep of effectDeps) {
console.log({dep});
values.set(dep, [dep]);
const propsSource = derivedFromProps.get(dep);
if (propsSource != null) {
effectDerivedFromProps.set(dep, propsSource);
}
}
const setStateLocations: Array<SourceLocation> = [];
const setStateCalls: Array<SetStateCall> = [];
for (const block of effectFunction.body.blocks.values()) {
for (const pred of block.preds) {
if (!seenBlocks.has(pred)) {
@@ -150,6 +256,8 @@ function validateEffect(
}
for (const phi of block.phis) {
const aggregateDeps: Set<IdentifierId> = new Set();
let propsSource: Place | null = null;
for (const operand of phi.operands.values()) {
const deps = values.get(operand.identifier.id);
if (deps != null) {
@@ -157,10 +265,18 @@ function validateEffect(
aggregateDeps.add(dep);
}
}
const source = effectDerivedFromProps.get(operand.identifier.id);
if (source != null) {
propsSource = source;
}
}
if (aggregateDeps.size !== 0) {
values.set(phi.place.identifier.id, Array.from(aggregateDeps));
}
if (propsSource != null) {
effectDerivedFromProps.set(phi.place.identifier.id, propsSource);
}
}
for (const instr of block.instructions) {
switch (instr.value.kind) {
@@ -203,9 +319,16 @@ function validateEffect(
) {
const deps = values.get(instr.value.args[0].identifier.id);
if (deps != null && new Set(deps).size === effectDeps.length) {
setStateLocations.push(instr.value.callee.loc);
const propsSource = effectDerivedFromProps.get(
instr.value.args[0].identifier.id,
);
setStateCalls.push({
loc: instr.value.callee.loc,
propsSource: propsSource ?? null,
});
} else {
// doesn't depend on any deps
// doesn't depend on all deps
return;
}
}
@@ -215,6 +338,26 @@ function validateEffect(
return;
}
}
// Track props derivation through instruction effects
if (instr.effects != null) {
for (const effect of instr.effects) {
switch (effect.kind) {
case 'Assign':
case 'Alias':
case 'MaybeAlias':
case 'Capture': {
const source = effectDerivedFromProps.get(
effect.from.identifier.id,
);
if (source != null) {
effectDerivedFromProps.set(effect.into.identifier.id, source);
}
break;
}
}
}
}
}
for (const operand of eachTerminalOperand(block.terminal)) {
if (values.has(operand.identifier.id)) {
@@ -225,14 +368,29 @@ function validateEffect(
seenBlocks.add(block.id);
}
for (const loc of setStateLocations) {
errors.push({
category: ErrorCategory.EffectDerivationsOfState,
reason:
'Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
description: null,
loc,
suggestions: null,
});
for (const call of setStateCalls) {
if (call.propsSource != null) {
const propName = call.propsSource.identifier.name?.value;
const propInfo = propName != null ? ` (from prop '${propName}')` : '';
errors.push({
reason: `Consider lifting state up to the parent component to make this a controlled component. (https://react.dev/learn/you-might-not-need-an-effect#adjusting-some-state-when-a-prop-changes)`,
description: `You are using props${propInfo} to update local state in an effect.`,
severity: ErrorSeverity.InvalidReact,
loc: call.loc,
suggestions: null,
});
} else {
errors.push({
reason:
'You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)',
description:
'This effect updates state based on other state values. ' +
'Consider calculating this value directly during render',
severity: ErrorSeverity.InvalidReact,
loc: call.loc,
suggestions: null,
});
}
}
}

View File

@@ -24,13 +24,15 @@ function BadExample() {
```
Found 1 error:
Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
Error: You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
This effect updates state based on other state values. Consider calculating this value directly during render.
error.invalid-derived-computation-in-effect.ts:9:4
7 | const [fullName, setFullName] = useState('');
8 | useEffect(() => {
> 9 | setFullName(capitalize(firstName + ' ' + lastName));
| ^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
| ^^^^^^^^^^^ You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
10 | }, [firstName, lastName]);
11 |
12 | return <div>{fullName}</div>;

View File

@@ -34,13 +34,15 @@ export const FIXTURE_ENTRYPOINT = {
```
Found 1 error:
Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
Error: You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
error.derived-state-from-mixed-deps-no-error.ts:9:4
This effect updates state based on other state values. Consider calculating this value directly during render.
error.bug-derived-state-from-mixed-deps.ts:9:4
7 |
8 | useEffect(() => {
> 9 | setDisplayName(prefix + name);
| ^^^^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
| ^^^^^^^^^^^^^^ You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
10 | }, [prefix, name]);
11 |
12 | return (

View File

@@ -28,13 +28,15 @@ export const FIXTURE_ENTRYPOINT = {
```
Found 1 error:
Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
Error: You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
This effect updates state based on other state values. Consider calculating this value directly during render.
error.invalid-derived-state-from-props-destructured.ts:8:4
6 |
7 | useEffect(() => {
> 8 | setFullName(firstName + ' ' + lastName);
| ^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
| ^^^^^^^^^^^ You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
9 | }, [firstName, lastName]);
10 |
11 | return <div>{fullName}</div>;

View File

@@ -1,7 +1,7 @@
// @validateNoDerivedComputationsInEffects
import {useEffect, useState} from 'react';
function Component({user: {firstName, lastName}}) {
function Component({firstName, lastName}) {
const [fullName, setFullName] = useState('');
useEffect(() => {
@@ -13,5 +13,5 @@ function Component({user: {firstName, lastName}}) {
export const FIXTURE_ENTRYPOINT = {
fn: Component,
params: [{user: {firstName: 'John', lastName: 'Doe'}}],
params: [{firstName: 'John', lastName: 'Doe'}],
};

View File

@@ -28,13 +28,15 @@ export const FIXTURE_ENTRYPOINT = {
```
Found 1 error:
Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
Error: You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
This effect updates state based on other state values. Consider calculating this value directly during render.
error.invalid-derived-state-from-props-in-effect.ts:8:4
6 |
7 | useEffect(() => {
> 8 | setFullName(firstName + ' ' + lastName);
| ^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
| ^^^^^^^^^^^ You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
9 | }, [firstName, lastName]);
10 |
11 | return <div>{fullName}</div>;

View File

@@ -36,13 +36,15 @@ export const FIXTURE_ENTRYPOINT = {
```
Found 1 error:
Error: Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
Error: You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
This effect updates state based on other state values. Consider calculating this value directly during render.
error.invalid-derived-state-from-state-in-effect.ts:10:4
8 |
9 | useEffect(() => {
> 10 | setFullName(firstName + ' ' + lastName);
| ^^^^^^^^^^^ Values derived from props and state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
| ^^^^^^^^^^^ You may not need this effect. Values derived from state should be calculated during render, not in an effect. (https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state)
11 | }, [firstName, lastName]);
12 |
13 | return (