From dcbdf064915fc2187687acc12cf62232ab2b2a47 Mon Sep 17 00:00:00 2001
From: Joe Savona <joesavona@fb.com>
Date: Mon, 13 Nov 2023 11:03:00 -0800
Subject: [PATCH] Extra test case related to memoization "within" freeze

I found an interesting edge case in the previous diff with mutation of a value
that appears in the expression of an object key:

```javascript

const key = {}

const object = {

[mutateAndReturnOtherValue(key)]: 42,

};

mutate(key);

```

We analyze and represent this correctly all the way through to codegen, but then
we hit the bug that @mofeiZ has noticed before: the temporary for `t =
mutateAndReturnOtherValue(key)` isn't emitted immediately (bc its a temporary).
It gets emitted inside the memo block for `object`, which is incorrect.

I tried to reproduce that here with JSX and it works as expected. It's an
interesting case though so let's land this to ensure we don't regress.
---
 ...mutation-during-jsx-construction.expect.md | 53 +++++++++++++++++++
 .../mutation-during-jsx-construction.js       | 16 ++++++
 .../packages/sprout/src/shared-runtime.ts     |  5 ++
 3 files changed, 74 insertions(+)
 create mode 100644 compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.js

diff --git a/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.expect.md b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.expect.md
new file mode 100644
index 0000000000..5975d82411
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.expect.md
@@ -0,0 +1,53 @@
+
+## Input
+
+```javascript
+import { identity, mutate, mutateAndReturnNewValue } from "shared-runtime";
+
+function Component(props) {
+  const key = {};
+  // Key is modified by the function, but key itself is not frozen
+  const element = <div key={mutateAndReturnNewValue(key)}>{props.value}</div>;
+  // Key is later mutated here: this mutation must be grouped with the
+  // jsx construction above
+  mutate(key);
+  return element;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 42 }],
+};
+
+```
+
+## Code
+
+```javascript
+import { unstable_useMemoCache as useMemoCache } from "react";
+import { identity, mutate, mutateAndReturnNewValue } from "shared-runtime";
+
+function Component(props) {
+  const $ = useMemoCache(2);
+  let element;
+  if ($[0] !== props.value) {
+    const key = {};
+
+    element = <div key={mutateAndReturnNewValue(key)}>{props.value}</div>;
+
+    mutate(key);
+    $[0] = props.value;
+    $[1] = element;
+  } else {
+    element = $[1];
+  }
+  return element;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 42 }],
+};
+
+```
+      
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.js b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.js
new file mode 100644
index 0000000000..1d7302bce5
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/mutation-during-jsx-construction.js
@@ -0,0 +1,16 @@
+import { identity, mutate, mutateAndReturnNewValue } from "shared-runtime";
+
+function Component(props) {
+  const key = {};
+  // Key is modified by the function, but key itself is not frozen
+  const element = <div key={mutateAndReturnNewValue(key)}>{props.value}</div>;
+  // Key is later mutated here: this mutation must be grouped with the
+  // jsx construction above
+  mutate(key);
+  return element;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [{ value: 42 }],
+};
diff --git a/compiler/packages/sprout/src/shared-runtime.ts b/compiler/packages/sprout/src/shared-runtime.ts
index 928c064fee..880b5df848 100644
--- a/compiler/packages/sprout/src/shared-runtime.ts
+++ b/compiler/packages/sprout/src/shared-runtime.ts
@@ -73,6 +73,11 @@ export function mutateAndReturn<T>(arg: T): T {
   return arg;
 }
 
+export function mutateAndReturnNewValue<T>(arg: T): string {
+  mutate(arg);
+  return "hello!";
+}
+
 export function setProperty(arg: any, property: any): void {
   // don't mutate primitive
   if (typeof arg === null || typeof arg !== "object") {