[compiler] Fixes to enableTreatRefLikeIdentifiersAsRefs

We added the `@enableTreatRefLikeIdentifiersAsRefs` feature a while back but never enabled it. Since then we've continued to see examples that motivate this mode, so here we're fixing it up to prepare to enable by default. It now works as follows:

* If we find a property load or property store where both a) the object's name is ref-like (`ref` or `-Ref`) and b) the property is `current`, we infer the object itself as a ref and the value of the property as a ref value. Originally the feature only detected property loads, not stores.
* Inferred refs are not considered stable (this is a change from the original implementation). The only way to get a stable ref is by calling `useRef()`. We've seen issues with assuming refs are stable.

With this change, cases like the following now correctly error:

```js
function Foo(props) {
  const fooRef = props.fooRef;
  fooRef.current = true;
  ^^^^^^^^^^^^^^ cannot modify ref in render
}
```

Author: josephsavona

compiler/packages/babel-plugin-react-compiler/src/Inference/InferReactivePlaces.ts

@@ -21,7 +21,6 @@ import {
   isStableType,
   isStableTypeContainer,
   isUseOperator,
-  isUseRefType,
 } from '../HIR';
 import {PostDominator} from '../HIR/Dominator';
 import {
@@ -70,13 +69,6 @@ class StableSidemap {
               isStable: false,
             });
           }
-        } else if (
-          this.env.config.enableTreatRefLikeIdentifiersAsRefs &&
-          isUseRefType(lvalue.identifier)
-        ) {
-          this.map.set(lvalue.identifier.id, {
-            isStable: true,
-          });
         }
         break;
       }

compiler/packages/babel-plugin-react-compiler/src/TypeInference/InferTypes.ts

@@ -466,7 +466,31 @@ function* generateInstructionTypes(
       yield equation(left, returnType);
       break;
     }
-    case 'PropertyStore':
+    case 'PropertyStore': {
+      /**
+       * Infer types based on assignments to known object properties
+       * This is important for refs, where assignment to `<maybeRef>.current`
+       * can help us infer that an object itself is a ref
+       */
+      yield equation(
+        {
+          kind: 'Property',
+          objectType: value.object.identifier.type,
+          objectName: getName(names, value.object.identifier.id),
+          propertyName: {
+            kind: 'literal',
+            value: value.property,
+          },
+        },
+        /**
+         * We don't want the rvalue to be assigned a RefValue type just
+         * because it was assigned as the ref's value, since that twill trigger
+         * additional errors about accessing ref values during render.
+         */
+        makeType(),
+      );
+      break;
+    }
     case 'DeclareLocal':
     case 'RegExpLiteral':
     case 'MetaProperty':

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-assign-current-inferred-ref-during-render.expect.md

@@ -0,0 +1,24 @@
+
+## Input
+
+```javascript
+import {makeObject_Primitives} from 'shared-runtime';
+
+// @flow @enableTreatRefLikeIdentifiersAsRefs
+component Example() {
+  const fooRef = makeObject_Primitives();
+  fooRef.current = true;
+
+  return <Stringify foo={fooRef} />;
+}
+
+```
+
+
+## Error
+
+```
+Missing semicolon. (4:9)
+```
+          
+      

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-assign-current-inferred-ref-during-render.js

@@ -0,0 +1,9 @@
+import {makeObject_Primitives} from 'shared-runtime';
+
+// @flow @enableTreatRefLikeIdentifiersAsRefs
+component Example() {
+  const fooRef = makeObject_Primitives();
+  fooRef.current = true;
+
+  return <Stringify foo={fooRef} />;
+}

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

@@ -47,28 +47,32 @@ function useCustomRef() {
 function _temp() {}
 
 function Foo() {
-  const $ = _c(3);
+  const $ = _c(4);
   const ref = useCustomRef();
   let t0;
-  let t1;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[0] !== ref) {
     t0 = () => {
       ref.current?.click();
     };
+    $[0] = ref;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  let t1;
+  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
     t1 = [];
-    $[0] = t0;
-    $[1] = t1;
+    $[2] = t1;
   } else {
-    t0 = $[0];
-    t1 = $[1];
+    t1 = $[2];
   }
   useEffect(t0, t1);
   let t2;
-  if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
     t2 = <div>foo</div>;
-    $[2] = t2;
+    $[3] = t2;
   } else {
-    t2 = $[2];
+    t2 = $[3];
   }
   return t2;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ref-like-name-in-useCallback-2.expect.md

@@ -14,7 +14,7 @@ function Foo() {
 
   const onClick = useCallback(() => {
     ref.current?.click();
-  }, []);
+  }, [ref]);
 
   return <button onClick={onClick} />;
 }
@@ -47,24 +47,26 @@ function useCustomRef() {
 function _temp() {}
 
 function Foo() {
-  const $ = _c(2);
+  const $ = _c(4);
   const ref = useCustomRef();
   let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[0] !== ref) {
     t0 = () => {
       ref.current?.click();
     };
-    $[0] = t0;
+    $[0] = ref;
+    $[1] = t0;
   } else {
-    t0 = $[0];
+    t0 = $[1];
   }
   const onClick = t0;
   let t1;
-  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[2] !== onClick) {
     t1 = <button onClick={onClick} />;
-    $[1] = t1;
+    $[2] = onClick;
+    $[3] = t1;
   } else {
-    t1 = $[1];
+    t1 = $[3];
   }
   return t1;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ref-like-name-in-useCallback-2.js

@@ -10,7 +10,7 @@ function Foo() {
 
   const onClick = useCallback(() => {
     ref.current?.click();
-  }, []);
+  }, [ref]);
 
   return <button onClick={onClick} />;
 }

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

@@ -14,7 +14,7 @@ function Foo() {
 
   const onClick = useCallback(() => {
     customRef.current?.click();
-  }, []);
+  }, [customRef]);
 
   return <button onClick={onClick} />;
 }
@@ -47,24 +47,26 @@ function useCustomRef() {
 function _temp() {}
 
 function Foo() {
-  const $ = _c(2);
+  const $ = _c(4);
   const customRef = useCustomRef();
   let t0;
-  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[0] !== customRef) {
     t0 = () => {
       customRef.current?.click();
     };
-    $[0] = t0;
+    $[0] = customRef;
+    $[1] = t0;
   } else {
-    t0 = $[0];
+    t0 = $[1];
   }
   const onClick = t0;
   let t1;
-  if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
+  if ($[2] !== onClick) {
     t1 = <button onClick={onClick} />;
-    $[1] = t1;
+    $[2] = onClick;
+    $[3] = t1;
   } else {
-    t1 = $[1];
+    t1 = $[3];
   }
   return t1;
 }

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/ref-like-name-in-useCallback.js

@@ -10,7 +10,7 @@ function Foo() {
 
   const onClick = useCallback(() => {
     customRef.current?.click();
-  }, []);
+  }, [customRef]);
 
   return <button onClick={onClick} />;
 }