[compiler] ref guards apply up to fallthrough of the test

Fixes #30782

When developers do an `if (ref.current == null)` guard for lazy ref initialization, the "safe" blocks should extend up to the if's fallthrough. Previously we only allowed writing to the ref in the if consequent, but this meant that you couldn't use a ternary, logical, etc in the if body.

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

@@ -608,7 +608,7 @@ export const EnvironmentConfigSchema = z.object({
    *
    * Here the variables `ref` and `myRef` will be typed as Refs.
    */
-  enableTreatRefLikeIdentifiersAsRefs: z.boolean().default(false),
+  enableTreatRefLikeIdentifiersAsRefs: z.boolean().default(true),
 
   /*
    * If specified a value, the compiler lowers any calls to `useContext` to use

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateNoRefAccessInRender.ts

@@ -27,6 +27,7 @@ import {
   eachTerminalOperand,
 } from '../HIR/visitors';
 import {Err, Ok, Result} from '../Utils/Result';
+import {retainWhere} from '../Utils/utils';
 
 /**
  * Validates that a function does not access a ref value during render. This includes a partial check
@@ -279,9 +280,10 @@ function validateNoRefAccessInRenderImpl(
   for (let i = 0; (i == 0 || env.hasChanged()) && i < 10; i++) {
     env.resetChanged();
     returnValues = [];
-    const safeBlocks = new Map<BlockId, RefId>();
+    const safeBlocks: Array<{block: BlockId; ref: RefId}> = [];
     const errors = new CompilerError();
     for (const [, block] of fn.body.blocks) {
+      retainWhere(safeBlocks, entry => entry.block !== block.id);
       for (const phi of block.phis) {
         env.set(
           phi.place.identifier.id,
@@ -432,15 +434,11 @@ function validateNoRefAccessInRenderImpl(
                  * By default we check that function call operands are not refs,
                  * ref values, or functions that can access refs.
                  */
-                if (
-                  isRefLValue ||
-                  interpolatedAsJsx.has(instr.lvalue.identifier.id) ||
-                  hookKind != null
-                ) {
+                if (isRefLValue || hookKind != null) {
                   /**
                    * Special cases:
                    *
-                   * 1) the lvalue is a ref
+                   * 1. the lvalue is a ref
                    * In general passing a ref to a function may access that ref
                    * value during render, so we disallow it.
                    *
@@ -452,18 +450,21 @@ function validateNoRefAccessInRenderImpl(
                    *
                    * Eg `const mergedRef = mergeRefs(ref1, ref2)`
                    *
-                   * 2) the lvalue is passed as a jsx child
-                   *
-                   * For example `<Foo>{renderHelper(ref)}</Foo>`. Here we have more
-                   * context and infer that the ref is being passed to a component-like
-                   * render function which attempts to obey the rules.
-                   *
-                   * 3) hooks
+                   * 2. calling hooks
                    *
                    * Hooks are independently checked to ensure they don't access refs
                    * during render.
                    */
                   validateNoDirectRefValueAccess(errors, operand, env);
+                } else if (interpolatedAsJsx.has(instr.lvalue.identifier.id)) {
+                  /**
+                   * Special case: the lvalue is passed as a jsx child
+                   *
+                   * For example `<Foo>{renderHelper(ref)}</Foo>`. Here we have more
+                   * context and infer that the ref is being passed to a component-like
+                   * render function which attempts to obey the rules.
+                   */
+                  validateNoRefValueAccess(errors, env, operand);
                 } else {
                   validateNoRefPassedToFunction(
                     errors,
@@ -504,15 +505,17 @@ function validateNoRefAccessInRenderImpl(
           case 'PropertyStore':
           case 'ComputedDelete':
           case 'ComputedStore': {
-            const safe = safeBlocks.get(block.id);
             const target = env.get(instr.value.object.identifier.id);
+            let safe: (typeof safeBlocks)['0'] | null | undefined = null;
             if (
               instr.value.kind === 'PropertyStore' &&
-              safe != null &&
-              target?.kind === 'Ref' &&
-              target.refId === safe
+              target != null &&
+              target.kind === 'Ref'
             ) {
-              safeBlocks.delete(block.id);
+              safe = safeBlocks.find(entry => entry.ref === target.refId);
+            }
+            if (safe != null) {
+              retainWhere(safeBlocks, entry => entry !== safe);
             } else {
               validateNoRefUpdate(errors, env, instr.value.object, instr.loc);
             }
@@ -600,8 +603,11 @@ function validateNoRefAccessInRenderImpl(
 
       if (block.terminal.kind === 'if') {
         const test = env.get(block.terminal.test.identifier.id);
-        if (test?.kind === 'Guard') {
-          safeBlocks.set(block.terminal.consequent, test.refId);
+        if (
+          test?.kind === 'Guard' &&
+          safeBlocks.find(entry => entry.ref === test.refId) == null
+        ) {
+          safeBlocks.push({block: block.terminal.fallthrough, ref: test.refId});
         }
       }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect-indirect.expect.md

@@ -27,6 +27,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -100,8 +101,10 @@ function Component() {
   return t6;
 }
 
-function Child(t0) {
-  const { ref } = t0;
+function Child({ ref }) {
+  "use no memo";
+  // This violates the rules of React, so we access the ref in a child
+  // component
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect-indirect.js

@@ -23,6 +23,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect.expect.md

@@ -23,6 +23,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -86,8 +87,10 @@ function Component() {
   return t5;
 }
 
-function Child(t0) {
-  const { ref } = t0;
+function Child({ ref }) {
+  "use no memo";
+  // This violates the rules of React, so we access the ref in a child
+  // component
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-effect.js

@@ -19,6 +19,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-unused-callback-nested.expect.md

@@ -25,6 +25,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;
@@ -83,8 +84,10 @@ function Component() {
 }
 function _temp() {}
 
-function Child(t0) {
-  const { ref } = t0;
+function Child({ ref }) {
+  "use no memo";
+  // This violates the rules of React, so we access the ref in a child
+  // component
   return ref.current;
 }
 

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-access-in-unused-callback-nested.js

@@ -21,6 +21,7 @@ function Component() {
 }
 
 function Child({ref}) {
+  'use no memo';
   // This violates the rules of React, so we access the ref in a child
   // component
   return ref.current;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-lazy-initialization-with-logical.expect.md

@@ -0,0 +1,68 @@
+
+## Input
+
+```javascript
+// @validateRefAccessDuringRender
+
+import {useRef} from 'react';
+
+function Component(props) {
+  const ref = useRef(null);
+  if (ref.current == null) {
+    // the logical means the ref write is in a different block
+    // from the if consequent. this tests that the "safe" blocks
+    // extend up to the if's fallthrough
+    ref.current = props.unknownKey ?? props.value;
+  }
+  return <Child ref={ref} />;
+}
+
+function Child({ref}) {
+  'use no memo';
+  return ref.current;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 42}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validateRefAccessDuringRender
+
+import { useRef } from "react";
+
+function Component(props) {
+  const $ = _c(1);
+  const ref = useRef(null);
+  if (ref.current == null) {
+    ref.current = props.unknownKey ?? props.value;
+  }
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <Child ref={ref} />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+function Child({ ref }) {
+  "use no memo";
+  return ref.current;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 42 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) 42

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/allow-ref-lazy-initialization-with-logical.js

@@ -0,0 +1,24 @@
+// @validateRefAccessDuringRender
+
+import {useRef} from 'react';
+
+function Component(props) {
+  const ref = useRef(null);
+  if (ref.current == null) {
+    // the logical means the ref write is in a different block
+    // from the if consequent. this tests that the "safe" blocks
+    // extend up to the if's fallthrough
+    ref.current = props.unknownKey ?? props.value;
+  }
+  return <Child ref={ref} />;
+}
+
+function Child({ref}) {
+  'use no memo';
+  return ref.current;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{value: 42}],
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-aliased-ref-in-callback-invoked-during-render-.expect.md

@@ -29,7 +29,7 @@ error.invalid-aliased-ref-in-callback-invoked-during-render-.ts:9:33
    7 |     return <Foo item={item} current={current} />;
    8 |   };
 >  9 |   return <Items>{props.items.map(item => renderItem(item))}</Items>;
-     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Passing a ref to a function may read its value during render
+     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Cannot access ref value during render
   10 | }
   11 |
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-ref-in-callback-invoked-during-render.expect.md

@@ -28,7 +28,7 @@ error.invalid-ref-in-callback-invoked-during-render.ts:8:33
    6 |     return <Foo item={item} current={current} />;
    7 |   };
 >  8 |   return <Items>{props.items.map(item => renderItem(item))}</Items>;
-     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Passing a ref to a function may read its value during render
+     |                                  ^^^^^^^^^^^^^^^^^^^^^^^^ Cannot access ref value during render
    9 | }
   10 |
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.repro-ref-mutable-range.expect.md

@@ -1,47 +0,0 @@
-
-## Input
-
-```javascript
-import {Stringify, identity, mutate, CONST_TRUE} from 'shared-runtime';
-
-function Foo(props, ref) {
-  const value = {};
-  if (CONST_TRUE) {
-    mutate(value);
-    return <Stringify ref={ref} />;
-  }
-  mutate(value);
-  if (CONST_TRUE) {
-    return <Stringify ref={identity(ref)} />;
-  }
-  return value;
-}
-
-export const FIXTURE_ENTRYPOINT = {
-  fn: Foo,
-  params: [{}, {current: 'fake-ref-object'}],
-};
-
-```
-
-
-## Error
-
-```
-Found 1 error:
-
-Error: Cannot access refs during render
-
-React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)
-
-error.repro-ref-mutable-range.ts:11:36
-   9 |   mutate(value);
-  10 |   if (CONST_TRUE) {
-> 11 |     return <Stringify ref={identity(ref)} />;
-     |                                     ^^^ Passing a ref to a function may read its value during render
-  12 |   }
-  13 |   return value;
-  14 | }
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/bailout-retry/mutate-after-useeffect-ref-access.expect.md

@@ -47,7 +47,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":158},"end":{"line":11,"column":1,"index":331},"filename":"mutate-after-useeffect-ref-access.ts"},"detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying component props or hook arguments is not allowed. Consider using a local variable instead.","details":[{"kind":"error","loc":{"start":{"line":9,"column":2,"index":289},"end":{"line":9,"column":16,"index":303},"filename":"mutate-after-useeffect-ref-access.ts"},"message":"value cannot be modified"}]}}}
+{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":158},"end":{"line":11,"column":1,"index":331},"filename":"mutate-after-useeffect-ref-access.ts"},"detail":{"options":{"severity":"InvalidReact","category":"Cannot access refs during render","description":"React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)","details":[{"kind":"error","loc":{"start":{"line":9,"column":2,"index":289},"end":{"line":9,"column":16,"index":303},"filename":"mutate-after-useeffect-ref-access.ts"},"message":"Cannot update ref during render"}]}}}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":8,"column":2,"index":237},"end":{"line":8,"column":50,"index":285},"filename":"mutate-after-useeffect-ref-access.ts"},"decorations":[{"start":{"line":8,"column":24,"index":259},"end":{"line":8,"column":30,"index":265},"filename":"mutate-after-useeffect-ref-access.ts","identifierName":"arrRef"}]}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":158},"end":{"line":11,"column":1,"index":331},"filename":"mutate-after-useeffect-ref-access.ts"},"fnName":"Component","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/infer-effect-dependencies/nonreactive-ref-helper.expect.md

@@ -51,12 +51,12 @@ function RefsInEffects() {
   const ref = useRefHelper();
   const wrapped = useDeeperRefHelper();
   let t0;
-  if ($[0] !== ref.current || $[1] !== wrapped.foo.current) {
+  if ($[0] !== ref || $[1] !== wrapped.foo.current) {
     t0 = () => {
       print(ref.current);
       print(wrapped.foo.current);
     };
-    $[0] = ref.current;
+    $[0] = ref;
     $[1] = wrapped.foo.current;
     $[2] = t0;
   } else {

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/new-mutability/mutate-after-useeffect-ref-access.expect.md

@@ -47,7 +47,7 @@ export const FIXTURE_ENTRYPOINT = {
 ## Logs
 
 ```
-{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":190},"end":{"line":11,"column":1,"index":363},"filename":"mutate-after-useeffect-ref-access.ts"},"detail":{"options":{"severity":"InvalidReact","category":"This value cannot be modified","description":"Modifying component props or hook arguments is not allowed. Consider using a local variable instead.","details":[{"kind":"error","loc":{"start":{"line":9,"column":2,"index":321},"end":{"line":9,"column":16,"index":335},"filename":"mutate-after-useeffect-ref-access.ts"},"message":"value cannot be modified"}]}}}
+{"kind":"CompileError","fnLoc":{"start":{"line":6,"column":0,"index":190},"end":{"line":11,"column":1,"index":363},"filename":"mutate-after-useeffect-ref-access.ts"},"detail":{"options":{"severity":"InvalidReact","category":"Cannot access refs during render","description":"React refs are values that are not needed for rendering. Refs should only be accessed outside of render, such as in event handlers or effects. Accessing a ref value (the `current` property) during render can cause your component not to update as expected (https://react.dev/reference/react/useRef)","details":[{"kind":"error","loc":{"start":{"line":9,"column":2,"index":321},"end":{"line":9,"column":16,"index":335},"filename":"mutate-after-useeffect-ref-access.ts"},"message":"Cannot update ref during render"}]}}}
 {"kind":"AutoDepsDecorations","fnLoc":{"start":{"line":8,"column":2,"index":269},"end":{"line":8,"column":50,"index":317},"filename":"mutate-after-useeffect-ref-access.ts"},"decorations":[{"start":{"line":8,"column":24,"index":291},"end":{"line":8,"column":30,"index":297},"filename":"mutate-after-useeffect-ref-access.ts","identifierName":"arrRef"}]}
 {"kind":"CompileSuccess","fnLoc":{"start":{"line":6,"column":0,"index":190},"end":{"line":11,"column":1,"index":363},"filename":"mutate-after-useeffect-ref-access.ts"},"fnName":"Component","memoSlots":0,"memoBlocks":0,"memoValues":0,"prunedMemoBlocks":0,"prunedMemoValues":0}
 ```

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.maybe-invalid-useCallback-read-maybeRef.expect.md

@@ -1,39 +0,0 @@
-
-## Input
-
-```javascript
-// @validatePreserveExistingMemoizationGuarantees
-import {useCallback} from 'react';
-
-function useHook(maybeRef) {
-  return useCallback(() => {
-    return [maybeRef.current];
-  }, [maybeRef]);
-}
-
-```
-
-
-## Error
-
-```
-Found 1 error:
-
-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. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `maybeRef.current`, but the source dependencies were [maybeRef]. Differences in ref.current access.
-
-error.maybe-invalid-useCallback-read-maybeRef.ts:5:21
-  3 |
-  4 | function useHook(maybeRef) {
-> 5 |   return useCallback(() => {
-    |                      ^^^^^^^
-> 6 |     return [maybeRef.current];
-    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-> 7 |   }, [maybeRef]);
-    | ^^^^ Could not preserve existing manual memoization
-  8 | }
-  9 |
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.maybe-invalid-useMemo-read-maybeRef.expect.md

@@ -1,39 +0,0 @@
-
-## Input
-
-```javascript
-// @validatePreserveExistingMemoizationGuarantees
-import {useMemo} from 'react';
-
-function useHook(maybeRef, shouldRead) {
-  return useMemo(() => {
-    return () => [maybeRef.current];
-  }, [shouldRead, maybeRef]);
-}
-
-```
-
-
-## Error
-
-```
-Found 1 error:
-
-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. The inferred dependencies did not match the manually specified dependencies, which could cause the value to change more or less frequently than expected. The inferred dependency was `maybeRef.current`, but the source dependencies were [shouldRead, maybeRef]. Differences in ref.current access.
-
-error.maybe-invalid-useMemo-read-maybeRef.ts:5:17
-  3 |
-  4 | function useHook(maybeRef, shouldRead) {
-> 5 |   return useMemo(() => {
-    |                  ^^^^^^^
-> 6 |     return () => [maybeRef.current];
-    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-> 7 |   }, [shouldRead, maybeRef]);
-    | ^^^^ Could not preserve existing manual memoization
-  8 | }
-  9 |
-```
-          
-      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/repro-maybe-invalid-useCallback-read-maybeRef.expect.md

@@ -0,0 +1,38 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {useCallback} from 'react';
+
+function useHook(maybeRef) {
+  return useCallback(() => {
+    return [maybeRef.current];
+  }, [maybeRef]);
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validatePreserveExistingMemoizationGuarantees
+import { useCallback } from "react";
+
+function useHook(maybeRef) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== maybeRef) {
+    t0 = () => [maybeRef.current];
+    $[0] = maybeRef;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/repro-maybe-invalid-useMemo-read-maybeRef.expect.md

@@ -0,0 +1,38 @@
+
+## Input
+
+```javascript
+// @validatePreserveExistingMemoizationGuarantees
+import {useMemo} from 'react';
+
+function useHook(maybeRef, shouldRead) {
+  return useMemo(() => {
+    return () => [maybeRef.current];
+  }, [shouldRead, maybeRef]);
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @validatePreserveExistingMemoizationGuarantees
+import { useMemo } from "react";
+
+function useHook(maybeRef, shouldRead) {
+  const $ = _c(2);
+  let t0;
+  if ($[0] !== maybeRef) {
+    t0 = () => [maybeRef.current];
+    $[0] = maybeRef;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  return t0;
+}
+
+```
+      
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/repro-ref-mutable-range.expect.md

@@ -0,0 +1,89 @@
+
+## Input
+
+```javascript
+import {Stringify, identity, mutate, CONST_TRUE} from 'shared-runtime';
+
+function Foo(props, ref) {
+  const value = {};
+  if (CONST_TRUE) {
+    mutate(value);
+    return <Stringify ref={ref} />;
+  }
+  mutate(value);
+  if (CONST_TRUE) {
+    return <Stringify ref={identity(ref)} />;
+  }
+  return value;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{}, {current: 'fake-ref-object'}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { Stringify, identity, mutate, CONST_TRUE } from "shared-runtime";
+
+function Foo(props, ref) {
+  const $ = _c(7);
+  let t0;
+  let value;
+  if ($[0] !== ref) {
+    t0 = Symbol.for("react.early_return_sentinel");
+    bb0: {
+      value = {};
+      if (CONST_TRUE) {
+        mutate(value);
+        t0 = <Stringify ref={ref} />;
+        break bb0;
+      }
+
+      mutate(value);
+    }
+    $[0] = ref;
+    $[1] = t0;
+    $[2] = value;
+  } else {
+    t0 = $[1];
+    value = $[2];
+  }
+  if (t0 !== Symbol.for("react.early_return_sentinel")) {
+    return t0;
+  }
+  if (CONST_TRUE) {
+    let t1;
+    if ($[3] !== ref) {
+      t1 = identity(ref);
+      $[3] = ref;
+      $[4] = t1;
+    } else {
+      t1 = $[4];
+    }
+    let t2;
+    if ($[5] !== t1) {
+      t2 = <Stringify ref={t1} />;
+      $[5] = t1;
+      $[6] = t2;
+    } else {
+      t2 = $[6];
+    }
+    return t2;
+  }
+  return value;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{}, { current: "fake-ref-object" }],
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"ref":{"current":"fake-ref-object"}}</div>