[compiler] Fix false negatives and add data flow tree to compiler error for no-deriving-state-in-effects
#34995
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This was referenced Oct 27, 2025
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jorge-cab
commented
Oct 28, 2025
| This setState call is setting a derived value that depends on the following reactive sources: | ||
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Oh wait Prop: [props] missing here seems like a bug
…d instead update typeOfValue and fix infinite loops
Summary:
With this we are now comparing a snapshot of the derivationCache with the new changes every time we are done recording the derivations happening in the HIR.
We have to do this after recording everything since we still do some mutations on the cache when recording mutations.
Test Plan:
Test the following in playground:
```
// @validateNoDerivedComputationsInEffects_exp
function Component({ value }) {
const [checked, setChecked] = useState('');
useEffect(() => {
setChecked(value === '' ? [] : value.split(','));
}, [value]);
return (
<div>{checked}</div>
)
}
```
This no longer causes an infinite loop.
Added a test case in the next PR in the stack
…or for `no-deriving-state-in-effects` Summary: Revamped the derivationCache graph. This fixes a bunch of bugs where sometimes we fail to track from which props/state we derived values from. Also, it is more intuitive and allows us to easily implement a Data Flow Tree. We can print this tree which gives insight on how the data is derived and should facilitate error resolution in complicated components Test Plan: Added a test case where we were failing to track derivations. Also updated the test cases with the new error containing the data flow tree
mofeiZ
reviewed
Oct 31, 2025
| Props: [props] | ||
| Data Flow Tree: | ||
| └── computed |
mofeiZ
reviewed
Oct 31, 2025
|
|
||
| if (newValue.sourcesIds.size === 0) { | ||
| newValue.sourcesIds.add(derivedVar.identifier.id); | ||
| if (isNamedIdentifier(sourceMetadata.place)) { |
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CompilerError.invariant(isNamedIdentifier(sourceMetadata.place), {
reason: "Compiler internal error: expected derivation entries to always reference named variables),
mofeiZ
reviewed
Oct 31, 2025
| } else { | ||
| newValue.sourcesIds.add(sourcePlace.identifier.id); | ||
| } | ||
| if (sourceMetadata === undefined) { |
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We checked if all calls to addDerivationEntry only add known-sourceIds, so this should be safe to remove (or assert with CompilerError.invariant)
mofeiZ
reviewed
Oct 31, 2025
| context.derivationCache.cache.set(param.identifier.id, { | ||
| place: param, | ||
| sourcesIds: new Set([param.identifier.id]), | ||
| sourcesIds: new Set( |
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Can we add a todo comment and/or fixture for what might be missed by this isNamedIdentifier check?
(pseudocode)
hook useMyHook({x, y, z}) {
const fromPropValue = x + 2;
useEffect(() => setState(fromPropValue), [fromPropValue]);
}
mofeiZ
approved these changes
Oct 31, 2025
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Summary:
Revamped the derivationCache graph.
This fixes a bunch of bugs where sometimes we fail to track from which props/state we derived values from.
Also, it is more intuitive and allows us to easily implement a Data Flow Tree.
We can print this tree which gives insight on how the data is derived and should facilitate error resolution in complicated components
Test Plan:
Added a test case where we were failing to track derivations. Also updated the test cases with the new error containing the data flow tree
Stack created with Sapling. Best reviewed with ReviewStack.
no-deriving-state-in-effects#34995