[compiler] Fix AnalyzeFunctions to fully reset context identifiers (#33500)
AnalyzeFunctions had logic to reset the mutable ranges of context variables after visiting inner function expressions. However, there was a bug in that logic: InferReactiveScopeVariables makes all the identifiers in a scope point to the same mutable range instance. That meant that it was possible for a later function expression to indirectly cause an earlier function expressions' context variables to get a non-zero mutable range. The fix is to not just reset start/end of context var ranges, but assign a new range instance. Thanks for the help on debugging, @mofeiz! --- [//]: # (BEGIN SAPLING FOOTER) Stack created with [Sapling](https://sapling-scm.com). Best reviewed with [ReviewStack](https://reviewstack.dev/facebook/react/pull/33500). * #33571 * #33558 * #33547 * #33543 * #33533 * #33532 * #33530 * #33526 * #33522 * #33518 * #33514 * #33513 * #33512 * #33504 * __->__ #33500 * #33497 * #33496
Joseph Savona committed
Jun 18, 2025 at 13:02 UTC
7c28c154651f54a63a6823e4dc54faa218c05a89
3 files changed
+115
-2
compiler/packages/babel-plugin-react-compiler/src/Inference/AnalyseFunctions.ts
+10
-2
@@ -42,8 +42,16 @@ export default function analyseFunctions(func: HIRFunction): void {
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* Reset mutable range for outer inferReferenceEffects
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*/
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for (const operand of instr.value.loweredFunc.func.context) {
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- operand.identifier.mutableRange.start = makeInstructionId(0);
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- operand.identifier.mutableRange.end = makeInstructionId(0);
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+ /**
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+ * NOTE: inferReactiveScopeVariables makes identifiers in the scope
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+ * point to the *same* mutableRange instance. Resetting start/end
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+ * here is insufficient, because a later mutation of the range
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+ * for any one identifier could affect the range for other identifiers.
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+ */
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+ operand.identifier.mutableRange = {
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+ start: makeInstructionId(0),
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+ end: makeInstructionId(0),
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+ };
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operand.identifier.scope = null;
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}
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break;
compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/repro-internal-compiler-shared-mutablerange-bug.expect.md
new
+80
@@ -0,0 +1,80 @@
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+
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+## Input
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+
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+```javascript
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+//@flow @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel
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+component Component(
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+ onAsyncSubmit?: (() => void) => void,
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+ onClose: (isConfirmed: boolean) => void
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+) {
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+ // When running inferReactiveScopeVariables,
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+ // onAsyncSubmit and onClose update to share
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+ // a mutableRange instance.
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+ const onSubmit = useCallback(() => {
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+ if (onAsyncSubmit) {
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+ onAsyncSubmit(() => {
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+ onClose(true);
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+ });
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+ return;
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+ }
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+ }, [onAsyncSubmit, onClose]);
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+ // When running inferReactiveScopeVariables here,
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+ // first the existing range gets updated (affecting
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+ // onAsyncSubmit) and then onClose gets assigned a
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+ // different mutable range instance, which is the
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+ // one reset after AnalyzeFunctions.
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+ // The fix is to fully reset mutable ranges *instances*
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+ // after AnalyzeFunctions visit a function expression
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+ return <Dialog onSubmit={onSubmit} onClose={() => onClose(false)} />;
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+}
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+
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+```
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+
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+## Code
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+
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+```javascript
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+import { c as _c } from "react/compiler-runtime";
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+function Component(t0) {
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+ const $ = _c(8);
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+ const { onAsyncSubmit, onClose } = t0;
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+ let t1;
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+ if ($[0] !== onAsyncSubmit || $[1] !== onClose) {
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+ t1 = () => {
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+ if (onAsyncSubmit) {
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+ onAsyncSubmit(() => {
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+ onClose(true);
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+ });
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+ return;
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+ }
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+ };
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+ $[0] = onAsyncSubmit;
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+ $[1] = onClose;
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+ $[2] = t1;
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+ } else {
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+ t1 = $[2];
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+ }
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+ const onSubmit = t1;
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+ let t2;
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+ if ($[3] !== onClose) {
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+ t2 = () => onClose(false);
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+ $[3] = onClose;
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+ $[4] = t2;
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+ } else {
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+ t2 = $[4];
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+ }
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+ let t3;
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+ if ($[5] !== onSubmit || $[6] !== t2) {
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+ t3 = <Dialog onSubmit={onSubmit} onClose={t2} />;
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+ $[5] = onSubmit;
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+ $[6] = t2;
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+ $[7] = t3;
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+ } else {
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+ t3 = $[7];
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+ }
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+ return t3;
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+}
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+
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+```
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+
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+### Eval output
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+(kind: exception) Fixture not implemented
\ No newline at end of file
compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/repro-internal-compiler-shared-mutablerange-bug.js
new
+25
@@ -0,0 +1,25 @@
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+//@flow @validatePreserveExistingMemoizationGuarantees @enableNewMutationAliasingModel
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+component Component(
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+ onAsyncSubmit?: (() => void) => void,
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+ onClose: (isConfirmed: boolean) => void
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+) {
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+ // When running inferReactiveScopeVariables,
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+ // onAsyncSubmit and onClose update to share
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+ // a mutableRange instance.
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+ const onSubmit = useCallback(() => {
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+ if (onAsyncSubmit) {
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+ onAsyncSubmit(() => {
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+ onClose(true);
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+ });
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+ return;
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+ }
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+ }, [onAsyncSubmit, onClose]);
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+ // When running inferReactiveScopeVariables here,
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+ // first the existing range gets updated (affecting
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+ // onAsyncSubmit) and then onClose gets assigned a
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+ // different mutable range instance, which is the
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+ // one reset after AnalyzeFunctions.
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+ // The fix is to fully reset mutable ranges *instances*
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+ // after AnalyzeFunctions visit a function expression
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+ return <Dialog onSubmit={onSubmit} onClose={() => onClose(false)} />;
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+}