From 5ca2bc6d631dde8c221fa482cb8729a67115c7f9 Mon Sep 17 00:00:00 2001
From: mofeiZ <34200447+mofeiZ@users.noreply.github.com>
Date: Tue, 5 Nov 2024 17:56:53 -0500
Subject: [PATCH] [compiler][ez] Fixture repro for function hoisting bug
 (#31349)

Repro for bug reported by @alexmckenley
---
 .../bug-functiondecl-hoisting.expect.md       | 81 +++++++++++++++++++
 .../compiler/bug-functiondecl-hoisting.tsx    | 22 +++++
 .../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-functiondecl-hoisting.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.tsx

diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.expect.md
new file mode 100644
index 0000000000..2b0031b117
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.expect.md
@@ -0,0 +1,81 @@
+
+## Input
+
+```javascript
+import {Stringify} from 'shared-runtime';
+
+/**
+ * Fixture currently fails with
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) <div>{"result":{"value":2},"fn":{"kind":"Function","result":{"value":2}},"shouldInvokeFns":true}</div>
+ *   Forget:
+ *   (kind: exception) bar is not a function
+ */
+function Foo({value}) {
+  const result = bar();
+  function bar() {
+    return {value};
+  }
+  return <Stringify result={result} fn={bar} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{value: 2}],
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime";
+import { Stringify } from "shared-runtime";
+
+/**
+ * Fixture currently fails with
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) <div>{"result":{"value":2},"fn":{"kind":"Function","result":{"value":2}},"shouldInvokeFns":true}</div>
+ *   Forget:
+ *   (kind: exception) bar is not a function
+ */
+function Foo(t0) {
+  const $ = _c(6);
+  const { value } = t0;
+  let bar;
+  let result;
+  if ($[0] !== value) {
+    result = bar();
+    bar = function bar() {
+      return { value };
+    };
+    $[0] = value;
+    $[1] = bar;
+    $[2] = result;
+  } else {
+    bar = $[1];
+    result = $[2];
+  }
+
+  const t1 = bar;
+  let t2;
+  if ($[3] !== result || $[4] !== t1) {
+    t2 = <Stringify result={result} fn={t1} shouldInvokeFns={true} />;
+    $[3] = result;
+    $[4] = t1;
+    $[5] = t2;
+  } else {
+    t2 = $[5];
+  }
+  return t2;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{ value: 2 }],
+};
+
+```
+      
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.tsx b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.tsx
new file mode 100644
index 0000000000..c454101282
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/bug-functiondecl-hoisting.tsx
@@ -0,0 +1,22 @@
+import {Stringify} from 'shared-runtime';
+
+/**
+ * Fixture currently fails with
+ * Found differences in evaluator results
+ *   Non-forget (expected):
+ *   (kind: ok) <div>{"result":{"value":2},"fn":{"kind":"Function","result":{"value":2}},"shouldInvokeFns":true}</div>
+ *   Forget:
+ *   (kind: exception) bar is not a function
+ */
+function Foo({value}) {
+  const result = bar();
+  function bar() {
+    return {value};
+  }
+  return <Stringify result={result} fn={bar} shouldInvokeFns={true} />;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Foo,
+  params: [{value: 2}],
+};
diff --git a/compiler/packages/snap/src/SproutTodoFilter.ts b/compiler/packages/snap/src/SproutTodoFilter.ts
index 76914f1dd2..b868afc52b 100644
--- a/compiler/packages/snap/src/SproutTodoFilter.ts
+++ b/compiler/packages/snap/src/SproutTodoFilter.ts
@@ -480,6 +480,7 @@ const skipFilter = new Set([
   'fbt/bug-fbt-plural-multiple-mixed-call-tag',
   'bug-object-expression-computed-key-modified-during-after-construction-hoisted-sequence-expr',
   'bug-invalid-hoisting-functionexpr',
+  'bug-functiondecl-hoisting',
   'bug-try-catch-maybe-null-dependency',
   'reduce-reactive-deps/bug-infer-function-cond-access-not-hoisted',
   'bug-invalid-phi-as-dependency',