[compiler] Add definitions for Object entries/keys/values

Fixes remaining issue in #32261, where passing a previously useMemo()-d value to `Object.entries()` makes the compiler think the value is mutated and fail validatePreserveExistingMemo. While I was there I added Object.keys() and Object.values() too.

compiler/packages/babel-plugin-react-compiler/src/HIR/Globals.ts

@@ -114,6 +114,99 @@ const TYPED_GLOBALS: Array<[string, BuiltInType]> = [
           returnValueKind: ValueKind.Mutable,
         }),
       ],
+      [
+        'entries',
+        addFunction(DEFAULT_SHAPES, [], {
+          positionalParams: [Effect.Capture],
+          restParam: null,
+          returnType: {kind: 'Object', shapeId: BuiltInArrayId},
+          calleeEffect: Effect.Read,
+          returnValueKind: ValueKind.Mutable,
+          aliasing: {
+            receiver: '@receiver',
+            params: ['@object'],
+            rest: null,
+            returns: '@returns',
+            temporaries: [],
+            effects: [
+              {
+                kind: 'Create',
+                into: '@returns',
+                reason: ValueReason.KnownReturnSignature,
+                value: ValueKind.Mutable,
+              },
+              // Object values are captured into the return
+              {
+                kind: 'Capture',
+                from: '@object',
+                into: '@returns',
+              },
+            ],
+          },
+        }),
+      ],
+      [
+        'keys',
+        addFunction(DEFAULT_SHAPES, [], {
+          positionalParams: [Effect.Read],
+          restParam: null,
+          returnType: {kind: 'Object', shapeId: BuiltInArrayId},
+          calleeEffect: Effect.Read,
+          returnValueKind: ValueKind.Mutable,
+          aliasing: {
+            receiver: '@receiver',
+            params: ['@object'],
+            rest: null,
+            returns: '@returns',
+            temporaries: [],
+            effects: [
+              {
+                kind: 'Create',
+                into: '@returns',
+                reason: ValueReason.KnownReturnSignature,
+                value: ValueKind.Mutable,
+              },
+              // Only keys are captured, and keys are immutable
+              {
+                kind: 'ImmutableCapture',
+                from: '@object',
+                into: '@returns',
+              },
+            ],
+          },
+        }),
+      ],
+      [
+        'values',
+        addFunction(DEFAULT_SHAPES, [], {
+          positionalParams: [Effect.Capture],
+          restParam: null,
+          returnType: {kind: 'Object', shapeId: BuiltInArrayId},
+          calleeEffect: Effect.Read,
+          returnValueKind: ValueKind.Mutable,
+          aliasing: {
+            receiver: '@receiver',
+            params: ['@object'],
+            rest: null,
+            returns: '@returns',
+            temporaries: [],
+            effects: [
+              {
+                kind: 'Create',
+                into: '@returns',
+                reason: ValueReason.KnownReturnSignature,
+                value: ValueKind.Mutable,
+              },
+              // Object values are captured into the return
+              {
+                kind: 'Capture',
+                from: '@object',
+                into: '@returns',
+              },
+            ],
+          },
+        }),
+      ],
     ]),
   ],
   [

compiler/packages/babel-plugin-react-compiler/src/HIR/ObjectShape.ts

@@ -142,6 +142,7 @@ function parseAliasingSignatureConfig(
   const effects = typeConfig.effects.map(
     (effect: AliasingEffectConfig): AliasingEffect => {
       switch (effect.kind) {
+        case 'ImmutableCapture':
         case 'CreateFrom':
         case 'Capture':
         case 'Alias':

compiler/packages/babel-plugin-react-compiler/src/HIR/TypeSchema.ts

@@ -111,6 +111,19 @@ export const AliasEffectSchema: z.ZodType<AliasEffectConfig> = z.object({
   into: LifetimeIdSchema,
 });
 
+export type ImmutableCaptureEffectConfig = {
+  kind: 'ImmutableCapture';
+  from: string;
+  into: string;
+};
+
+export const ImmutableCaptureEffectSchema: z.ZodType<ImmutableCaptureEffectConfig> =
+  z.object({
+    kind: z.literal('ImmutableCapture'),
+    from: LifetimeIdSchema,
+    into: LifetimeIdSchema,
+  });
+
 export type CaptureEffectConfig = {
   kind: 'Capture';
   from: string;
@@ -187,6 +200,7 @@ export type AliasingEffectConfig =
   | AssignEffectConfig
   | AliasEffectConfig
   | CaptureEffectConfig
+  | ImmutableCaptureEffectConfig
   | ImpureEffectConfig
   | MutateEffectConfig
   | MutateTransitiveConditionallyConfig
@@ -199,6 +213,7 @@ export const AliasingEffectSchema: z.ZodType<AliasingEffectConfig> = z.union([
   AssignEffectSchema,
   AliasEffectSchema,
   CaptureEffectSchema,
+  ImmutableCaptureEffectSchema,
   ImpureEffectSchema,
   MutateEffectSchema,
   MutateTransitiveConditionallySchema,

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-entries-mutation.expect.md

@@ -0,0 +1,57 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = useMemo(() => Object.entries(object), [object]);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};
+
+```
+
+
+## Error
+
+```
+Found 2 errors:
+
+Memoization: Compilation skipped because existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This dependency may be mutated later, which could cause the value to change unexpectedly.
+
+error.validate-object-entries-mutation.ts:6:57
+  4 | function Component(props) {
+  5 |   const object = {object: props.object};
+> 6 |   const entries = useMemo(() => Object.entries(object), [object]);
+    |                                                          ^^^^^^ This dependency may be modified later
+  7 |   entries.map(([, value]) => {
+  8 |     value.updated = true;
+  9 |   });
+
+Memoization: Compilation skipped because existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output.
+
+error.validate-object-entries-mutation.ts:6:18
+  4 | function Component(props) {
+  5 |   const object = {object: props.object};
+> 6 |   const entries = useMemo(() => Object.entries(object), [object]);
+    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Could not preserve existing memoization
+  7 |   entries.map(([, value]) => {
+  8 |     value.updated = true;
+  9 |   });
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-entries-mutation.js

@@ -0,0 +1,16 @@
+// @validatePreserveExistingMemoizationGuarantees
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = useMemo(() => Object.entries(object), [object]);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-values-mutation.expect.md

@@ -0,0 +1,57 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const values = useMemo(() => Object.values(object), [object]);
+  values.map(value => {
+    value.updated = true;
+  });
+  return <Stringify values={values} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};
+
+```
+
+
+## Error
+
+```
+Found 2 errors:
+
+Memoization: Compilation skipped because existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This dependency may be mutated later, which could cause the value to change unexpectedly.
+
+error.validate-object-values-mutation.ts:6:55
+  4 | function Component(props) {
+  5 |   const object = {object: props.object};
+> 6 |   const values = useMemo(() => Object.values(object), [object]);
+    |                                                        ^^^^^^ This dependency may be modified later
+  7 |   values.map(value => {
+  8 |     value.updated = true;
+  9 |   });
+
+Memoization: Compilation skipped because existing memoization could not be preserved
+
+React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value was memoized in source but not in compilation output.
+
+error.validate-object-values-mutation.ts:6:17
+  4 | function Component(props) {
+  5 |   const object = {object: props.object};
+> 6 |   const values = useMemo(() => Object.values(object), [object]);
+    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Could not preserve existing memoization
+  7 |   values.map(value => {
+  8 |     value.updated = true;
+  9 |   });
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.validate-object-values-mutation.js

@@ -0,0 +1,16 @@
+// @validatePreserveExistingMemoizationGuarantees
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const values = useMemo(() => Object.values(object), [object]);
+  values.map(value => {
+    value.updated = true;
+  });
+  return <Stringify values={values} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-entries-mutation.expect.md

@@ -0,0 +1,57 @@
+
+## Input
+
+```javascript
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = Object.entries(object);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeObject_Primitives, Stringify } from "shared-runtime";
+
+function Component(props) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== props.object) {
+    const object = { object: props.object };
+    const entries = Object.entries(object);
+    entries.map(_temp);
+    t0 = <Stringify entries={entries} />;
+    $[0] = props.object;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+function _temp(t0) {
+  const [, value] = t0;
+  value.updated = true;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ object: { key: makeObject_Primitives() } }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"entries":[["object",{"key":{"a":0,"b":"value1","c":true},"updated":true}]]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-entries-mutation.js

@@ -0,0 +1,15 @@
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = Object.entries(object);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-keys.expect.md

@@ -0,0 +1,108 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [item.id, ref => <Stringify ref={ref} {...item} />])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.keys(record).map(id => (
+        <Stringify key={id} render={record[id]} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validatePreserveExistingMemoizationGuarantees
+import { useMemo } from "react";
+import { Stringify } from "shared-runtime";
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component(t0) {
+  const $ = _c(7);
+  const { items } = t0;
+  let t1;
+  if ($[0] !== items) {
+    t1 = Object.fromEntries(items.map(_temp));
+    $[0] = items;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const record = t1;
+  let t2;
+  if ($[2] !== record) {
+    t2 = Object.keys(record);
+    $[2] = record;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  let t3;
+  if ($[4] !== record || $[5] !== t2) {
+    t3 = (
+      <div>
+        {t2.map((id) => (
+          <Stringify key={id} render={record[id]} />
+        ))}
+      </div>
+    );
+    $[4] = record;
+    $[5] = t2;
+    $[6] = t3;
+  } else {
+    t3 = $[6];
+  }
+  return t3;
+}
+function _temp(item) {
+  return [item.id, (ref) => <Stringify ref={ref} {...item} />];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        { id: "0", name: "Hello" },
+        { id: "1", name: "World!" },
+      ],
+    },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div><div>{"render":"[[ function params=1 ]]"}</div><div>{"render":"[[ function params=1 ]]"}</div></div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-keys.js

@@ -0,0 +1,36 @@
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [item.id, ref => <Stringify ref={ref} {...item} />])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.keys(record).map(id => (
+        <Stringify key={id} render={record[id]} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-values-mutation.expect.md

@@ -0,0 +1,57 @@
+
+## Input
+
+```javascript
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = Object.entries(object);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { makeObject_Primitives, Stringify } from "shared-runtime";
+
+function Component(props) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== props.object) {
+    const object = { object: props.object };
+    const entries = Object.entries(object);
+    entries.map(_temp);
+    t0 = <Stringify entries={entries} />;
+    $[0] = props.object;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+function _temp(t0) {
+  const [, value] = t0;
+  value.updated = true;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ object: { key: makeObject_Primitives() } }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"entries":[["object",{"key":{"a":0,"b":"value1","c":true},"updated":true}]]}</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-values-mutation.js

@@ -0,0 +1,15 @@
+import {makeObject_Primitives, Stringify} from 'shared-runtime';
+
+function Component(props) {
+  const object = {object: props.object};
+  const entries = Object.entries(object);
+  entries.map(([, value]) => {
+    value.updated = true;
+  });
+  return <Stringify entries={entries} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{object: {key: makeObject_Primitives()}}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-values.expect.md

@@ -0,0 +1,103 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [
+          item.id,
+          {id: item.id, render: ref => <Stringify ref={ref} {...item} />},
+        ])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.values(record).map(({id, render}) => (
+        <Stringify key={id} render={render} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validatePreserveExistingMemoizationGuarantees
+import { useMemo } from "react";
+import { Stringify } from "shared-runtime";
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component(t0) {
+  const $ = _c(4);
+  const { items } = t0;
+  let t1;
+  if ($[0] !== items) {
+    t1 = Object.fromEntries(items.map(_temp));
+    $[0] = items;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const record = t1;
+  let t2;
+  if ($[2] !== record) {
+    t2 = <div>{Object.values(record).map(_temp2)}</div>;
+    $[2] = record;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+function _temp2(t0) {
+  const { id, render } = t0;
+  return <Stringify key={id} render={render} />;
+}
+function _temp(item) {
+  return [
+    item.id,
+    { id: item.id, render: (ref) => <Stringify ref={ref} {...item} /> },
+  ];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        { id: "0", name: "Hello" },
+        { id: "1", name: "World!" },
+      ],
+    },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div><div>{"render":"[[ function params=1 ]]"}</div><div>{"render":"[[ function params=1 ]]"}</div></div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/object-values.js

@@ -0,0 +1,39 @@
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [
+          item.id,
+          {id: item.id, render: ref => <Stringify ref={ref} {...item} />},
+        ])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.values(record).map(({id, render}) => (
+        <Stringify key={id} render={render} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-object-fromEntries-entries.expect.md

@@ -0,0 +1,97 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [item.id, ref => <Stringify ref={ref} {...item} />])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.entries(record).map(([id, render]) => (
+        <Stringify key={id} render={render} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validatePreserveExistingMemoizationGuarantees
+import { useMemo } from "react";
+import { Stringify } from "shared-runtime";
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component(t0) {
+  const $ = _c(4);
+  const { items } = t0;
+  let t1;
+  if ($[0] !== items) {
+    t1 = Object.fromEntries(items.map(_temp));
+    $[0] = items;
+    $[1] = t1;
+  } else {
+    t1 = $[1];
+  }
+  const record = t1;
+  let t2;
+  if ($[2] !== record) {
+    t2 = <div>{Object.entries(record).map(_temp2)}</div>;
+    $[2] = record;
+    $[3] = t2;
+  } else {
+    t2 = $[3];
+  }
+  return t2;
+}
+function _temp2(t0) {
+  const [id, render] = t0;
+  return <Stringify key={id} render={render} />;
+}
+function _temp(item) {
+  return [item.id, (ref) => <Stringify ref={ref} {...item} />];
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        { id: "0", name: "Hello" },
+        { id: "1", name: "World!" },
+      ],
+    },
+  ],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div><div>{"render":"[[ function params=1 ]]"}</div><div>{"render":"[[ function params=1 ]]"}</div></div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-object-fromEntries-entries.js

@@ -0,0 +1,36 @@
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+import {Stringify} from 'shared-runtime';
+
+// derived from https://github.com/facebook/react/issues/32261
+function Component({items}) {
+  const record = useMemo(
+    () =>
+      Object.fromEntries(
+        items.map(item => [item.id, ref => <Stringify ref={ref} {...item} />])
+      ),
+    [items]
+  );
+
+  // Without a declaration for Object.entries(), this would be assumed to mutate
+  // `record`, meaning existing memoization couldn't be preserved
+  return (
+    <div>
+      {Object.entries(record).map(([id, render]) => (
+        <Stringify key={id} render={render} />
+      ))}
+    </div>
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [
+    {
+      items: [
+        {id: '0', name: 'Hello'},
+        {id: '1', name: 'World!'},
+      ],
+    },
+  ],
+};