From 096e3431e440553217d2fffa7380b04abcba6ede Mon Sep 17 00:00:00 2001
From: Mofei Zhang <feifei0@meta.com>
Date: Mon, 30 Sep 2024 15:56:58 -0400
Subject: [PATCH] [compiler] Test fixture: non-reactive phi creates 'dangling
 ref' scope

ghstack-source-id: 5dba5c0b1d2e17c1d8d8a88a363f28ad7ac4746a
Pull Request resolved: https://github.com/facebook/react/pull/31103
---
 .../bug-invalid-phi-as-dependency.expect.md   | 73 +++++++++++++++++++
 .../bug-invalid-phi-as-dependency.tsx         | 30 ++++++++
 .../packages/snap/src/SproutTodoFilter.ts     |  1 +
 3 files changed, 104 insertions(+)
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.tsx

diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.expect.md
new file mode 100644
index 0000000000000..8114b8a3738bc
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.expect.md
@@ -0,0 +1,73 @@
+
+## Input
+
+```javascript
+import { CONST_TRUE, Stringify, setProperty } from "shared-runtime";
+
+function Component({arg}) {
+  const obj = CONST_TRUE ? {inner: {value: "hello"}} : null;
+  const boxedInner = [obj?.inner];
+  useHook();
+  setProperty(obj, arg);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error("invariant broken");
+  }
+  return <Stringify obj={obj} inner={boxedInner} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{arg: 0}],
+  sequentialRenders: [{arg: 0}, {arg: 1}]
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { CONST_TRUE, Stringify, setProperty } from "shared-runtime";
+
+function Component(t0) {
+  const $ = _c(5);
+  const { arg } = t0;
+  const obj = CONST_TRUE ? { inner: { value: "hello" } } : null;
+  const t1 = obj?.inner;
+  let t2;
+  if ($[0] !== t1) {
+    t2 = [t1];
+    $[0] = t1;
+    $[1] = t2;
+  } else {
+    t2 = $[1];
+  }
+  const boxedInner = t2;
+  useHook();
+  setProperty(obj, arg);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error("invariant broken");
+  }
+  let t3;
+  if ($[2] !== obj || $[3] !== boxedInner) {
+    t3 = <Stringify obj={obj} inner={boxedInner} />;
+    $[2] = obj;
+    $[3] = boxedInner;
+    $[4] = t3;
+  } else {
+    t3 = $[4];
+  }
+  return t3;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ arg: 0 }],
+  sequentialRenders: [{ arg: 0 }, { arg: 1 }],
+};
+
+```
+      
+### Eval output
+(kind: ok) [[ (exception in render) ReferenceError: useHook is not defined ]]
+[[ (exception in render) ReferenceError: useHook is not defined ]]
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.tsx b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.tsx
new file mode 100644
index 0000000000000..f3be6660623af
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-invalid-phi-as-dependency.tsx
@@ -0,0 +1,30 @@
+import { CONST_TRUE, Stringify, mutate, useIdentity } from "shared-runtime";
+
+/**
+ * Fixture showing an edge case for ReactiveScope variable propagation.
+ *
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   Forget:
+ *   <div>{"obj":{"inner":{"value":"hello"},"wat0":"joe"},"inner":["[[ cyclic ref *2 ]]"]}</div>
+ *   [[ (exception in render) Error: invariant broken ]]
+ *
+ */
+function Component() {
+  const obj = CONST_TRUE ? {inner: {value: "hello"}} : null;
+  const boxedInner = [obj?.inner];
+  useIdentity(null);
+  mutate(obj);
+  if (boxedInner[0] !== obj?.inner) {
+    throw new Error("invariant broken");
+  }
+  return <Stringify obj={obj} inner={boxedInner} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{arg: 0}],
+  sequentialRenders: [{arg: 0}, {arg: 1}]
+}
diff --git a/compiler/packages/snap/src/SproutTodoFilter.ts b/compiler/packages/snap/src/SproutTodoFilter.ts
index 8597f66dbd788..5baca4b5dcd62 100644
--- a/compiler/packages/snap/src/SproutTodoFilter.ts
+++ b/compiler/packages/snap/src/SproutTodoFilter.ts
@@ -479,6 +479,7 @@ const skipFilter = new Set([
   'fbt/bug-fbt-plural-multiple-mixed-call-tag',
   'bug-invalid-hoisting-functionexpr',
   'bug-try-catch-maybe-null-dependency',
+  'bug-invalid-phi-as-dependency',
   'reduce-reactive-deps/bug-infer-function-cond-access-not-hoisted',
   'reduce-reactive-deps/bug-merge-uncond-optional-chain-and-cond',
   'original-reactive-scopes-fork/bug-nonmutating-capture-in-unsplittable-memo-block',