[compiler] Fixture to show ref-in-render enforcement issue with useCallback

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.useCallback-ref-in-render.expect.md

@@ -0,0 +1,41 @@
+
+## Input
+
+```javascript
+// @flow @validateRefAccessDuringRender @validatePreserveExistingMemoizationGuarantees
+
+component Foo() {
+  const ref = useRef();
+
+  const s = useCallback(() => {
+    return ref.current;
+  });
+
+  return <a r={s} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [],
+};
+
+```
+
+
+## Error
+
+```
+   4 |   const ref = useRef();
+   5 |
+>  6 |   const s = useCallback(() => {
+     |                         ^^^^^^^
+>  7 |     return ref.current;
+     | ^^^^^^^^^^^^^^^^^^^^^^^
+>  8 |   });
+     | ^^^^ InvalidReact: Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef). Cannot access ref value at read $27:TObject<BuiltInFunction> (6:8)
+   9 |
+  10 |   return <a r={s} />;
+  11 | }
+```
+
+

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.useCallback-ref-in-render.js

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+// @flow @validateRefAccessDuringRender @validatePreserveExistingMemoizationGuarantees
+
+component Foo() {
+  const ref = useRef();
+
+  const s = useCallback(() => {
+    return ref.current;
+  });
+
+  return <a r={s} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [],
+};