[compiler] repro of false positive for ValidatePreserveManualMemo

ghstack-source-id: 235c5bae0828b79db758871006e4c091923ca5fd
Pull Request resolved: #30431

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.false-positive-useMemo-with-refs.flow.expect.md

@@ -0,0 +1,38 @@
+
+## Input
+
+```javascript
+// @flow @validatePreserveExistingMemoizationGuarantees
+import { identity } from "shared-runtime";
+
+component Component(
+  disableLocalRef,
+  ref,
+) {
+  const localRef = useFooRef();
+  const mergedRef = useMemo(() => {
+    return disableLocalRef ? ref : identity(ref, localRef);
+  }, [disableLocalRef, ref, localRef]);
+  return <div ref={mergedRef} />;
+}
+
+```
+
+
+## Error
+
+```
+   7 | ) {
+   8 |   const localRef = useFooRef();
+>  9 |   const mergedRef = useMemo(() => {
+     |                             ^^^^^^^
+> 10 |     return disableLocalRef ? ref : identity(ref, localRef);
+     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+> 11 |   }, [disableLocalRef, ref, localRef]);
+     | ^^^^ CannotPreserveMemoization: React Compiler has skipped optimizing this component because the existing manual memoization could not be preserved. This value may be mutated later, which could cause the value to change unexpectedly (9:11)
+  12 |   return <div ref={mergedRef} />;
+  13 | }
+  14 |
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/preserve-memo-validation/error.false-positive-useMemo-with-refs.flow.js

@@ -0,0 +1,13 @@
+// @flow @validatePreserveExistingMemoizationGuarantees
+import { identity } from "shared-runtime";
+
+component Component(
+  disableLocalRef,
+  ref,
+) {
+  const localRef = useFooRef();
+  const mergedRef = useMemo(() => {
+    return disableLocalRef ? ref : identity(ref, localRef);
+  }, [disableLocalRef, ref, localRef]);
+  return <div ref={mergedRef} />;
+}