[compiler] Prevent innaccurate derivation recording on FunctionExpressions on no-derived-computation-in-effects (#35173)

Summary:
The operands of a function expression are the elements passed as
context. This means that it doesn't make sense to record mutations for
them.

The relevant mutations will happen in the function body, so we need to
prevent FunctionExpression type instruction from running the logic for
effect mutations.

This was also causing some values to depend on themselves in some cases
triggering an infinite loop. Also added n invariant to prevent this
issue

Test Plan:
Added fixture test

---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/35173).
* #35174
* __->__ #35173
This commit is contained in:
Jorge Cabiedes
2025-11-20 10:44:45 -08:00
committed by GitHub
parent 8ac5f4eb36
commit 7ee974de92
3 changed files with 184 additions and 0 deletions

View File

@@ -52,6 +52,8 @@ type ValidationContext = {
readonly setStateUsages: Map<IdentifierId, Set<SourceLocation>>;
};
const MAX_FIXPOINT_ITERATIONS = 100;
class DerivationCache {
hasChanges: boolean = false;
cache: Map<IdentifierId, DerivationMetadata> = new Map();
@@ -224,6 +226,7 @@ export function validateNoDerivedComputationsInEffects_exp(
}
let isFirstPass = true;
let iterationCount = 0;
do {
context.derivationCache.takeSnapshot();
@@ -236,6 +239,19 @@ export function validateNoDerivedComputationsInEffects_exp(
context.derivationCache.checkForChanges();
isFirstPass = false;
iterationCount++;
CompilerError.invariant(iterationCount < MAX_FIXPOINT_ITERATIONS, {
reason:
'[ValidateNoDerivedComputationsInEffects] Fixpoint iteration failed to converge.',
description: `Fixpoint iteration exceeded ${MAX_FIXPOINT_ITERATIONS} iterations while tracking derivations. This suggests a cyclic dependency in the derivation cache.`,
details: [
{
kind: 'error',
loc: fn.loc,
message: `Exceeded ${MAX_FIXPOINT_ITERATIONS} iterations in ValidateNoDerivedComputationsInEffects`,
},
],
});
} while (context.derivationCache.snapshot());
for (const [, effect] of effectsCache) {
@@ -422,6 +438,14 @@ function recordInstructionDerivations(
);
}
if (value.kind === 'FunctionExpression') {
/*
* We don't want to record effect mutations of FunctionExpressions the mutations will happen in the
* function body and we will record them there.
*/
return;
}
for (const operand of eachInstructionOperand(instr)) {
switch (operand.effect) {
case Effect.Capture:
@@ -512,6 +536,19 @@ function buildTreeNode(
const namedSiblings: Set<string> = new Set();
for (const childId of sourceMetadata.sourcesIds) {
CompilerError.invariant(childId !== sourceId, {
reason:
'Unexpected self-reference: a value should not have itself as a source',
description: null,
details: [
{
kind: 'error',
loc: sourceMetadata.place.loc,
message: null,
},
],
});
const childNodes = buildTreeNode(
childId,
context,

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@@ -0,0 +1,115 @@
## Input
```javascript
// @validateNoDerivedComputationsInEffects_exp @loggerTestOnly
function Component() {
const [foo, setFoo] = useState({});
const [bar, setBar] = useState(new Set());
/*
* isChanged is considered context of the effect's function expression,
* if we don't bail out of effect mutation derivation tracking, isChanged
* will inherit the sources of the effect's function expression.
*
* This is innacurate and with the multiple passes ends up causing an infinite loop.
*/
useEffect(() => {
let isChanged = false;
const newData = foo.map(val => {
bar.someMethod(val);
isChanged = true;
});
if (isChanged) {
setFoo(newData);
}
}, [foo, bar]);
return (
<div>
{foo}, {bar}
</div>
);
}
```
## Code
```javascript
import { c as _c } from "react/compiler-runtime"; // @validateNoDerivedComputationsInEffects_exp @loggerTestOnly
function Component() {
const $ = _c(9);
let t0;
if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
t0 = {};
$[0] = t0;
} else {
t0 = $[0];
}
const [foo, setFoo] = useState(t0);
let t1;
if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
t1 = new Set();
$[1] = t1;
} else {
t1 = $[1];
}
const [bar] = useState(t1);
let t2;
let t3;
if ($[2] !== bar || $[3] !== foo) {
t2 = () => {
let isChanged = false;
const newData = foo.map((val) => {
bar.someMethod(val);
isChanged = true;
});
if (isChanged) {
setFoo(newData);
}
};
t3 = [foo, bar];
$[2] = bar;
$[3] = foo;
$[4] = t2;
$[5] = t3;
} else {
t2 = $[4];
t3 = $[5];
}
useEffect(t2, t3);
let t4;
if ($[6] !== bar || $[7] !== foo) {
t4 = (
<div>
{foo}, {bar}
</div>
);
$[6] = bar;
$[7] = foo;
$[8] = t4;
} else {
t4 = $[8];
}
return t4;
}
```
## Logs
```
{"kind":"CompileError","detail":{"options":{"description":"Using an effect triggers an additional render which can hurt performance and user experience, potentially briefly showing stale values to the user\n\nThis setState call is setting a derived value that depends on the following reactive sources:\n\nState: [foo, bar]\n\nData Flow Tree:\n└── newData\n ├── foo (State)\n └── bar (State)\n\nSee: https://react.dev/learn/you-might-not-need-an-effect#updating-state-based-on-props-or-state","category":"EffectDerivationsOfState","reason":"You might not need an effect. Derive values in render, not effects.","details":[{"kind":"error","loc":{"start":{"line":23,"column":6,"index":663},"end":{"line":23,"column":12,"index":669},"filename":"function-expression-mutation-edge-case.ts","identifierName":"setFoo"},"message":"This should be computed during render, not in an effect"}]}},"fnLoc":null}
{"kind":"CompileSuccess","fnLoc":{"start":{"line":3,"column":0,"index":64},"end":{"line":32,"column":1,"index":762},"filename":"function-expression-mutation-edge-case.ts"},"fnName":"Component","memoSlots":9,"memoBlocks":4,"memoValues":5,"prunedMemoBlocks":0,"prunedMemoValues":0}
```
### Eval output
(kind: exception) Fixture not implemented

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@@ -0,0 +1,32 @@
// @validateNoDerivedComputationsInEffects_exp @loggerTestOnly
function Component() {
const [foo, setFoo] = useState({});
const [bar, setBar] = useState(new Set());
/*
* isChanged is considered context of the effect's function expression,
* if we don't bail out of effect mutation derivation tracking, isChanged
* will inherit the sources of the effect's function expression.
*
* This is innacurate and with the multiple passes ends up causing an infinite loop.
*/
useEffect(() => {
let isChanged = false;
const newData = foo.map(val => {
bar.someMethod(val);
isChanged = true;
});
if (isChanged) {
setFoo(newData);
}
}, [foo, bar]);
return (
<div>
{foo}, {bar}
</div>
);
}