From 52875a72fef2722347e4aa37ed5da30d7bd4f31e Mon Sep 17 00:00:00 2001
From: Joe Savona <joesavona@fb.com>
Date: Wed, 6 Mar 2024 21:50:03 -0800
Subject: [PATCH] Invariant if codegen tries to emit a temporary as an
 identifier
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

For T181507827 — adds an invariant in codegen when emitting identifiers to
ensure that we only create babel Identifier nodes for nodes that the compiler
has explicitly promoted to valid, named identifiers. This means that we'll fail
for unnamed temporaries (previously caught), as well as promoted temporaries
that somehow didn't get renamed by RenameVariables (newly caught).
---
 .../ReactiveScopes/CodegenReactiveFunction.ts | 15 ++++++-----
 ...catch-within-function-expression.expect.md | 25 +++++++++++++++++++
 ...do-try-catch-within-function-expression.js | 10 ++++++++
 3 files changed, 44 insertions(+), 6 deletions(-)
 create mode 100644 compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.js

diff --git a/compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/CodegenReactiveFunction.ts b/compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/CodegenReactiveFunction.ts
index 77b9414706..1f75d32067 100644
--- a/compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/CodegenReactiveFunction.ts
+++ b/compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/CodegenReactiveFunction.ts
@@ -2060,11 +2060,14 @@ function codegenPlace(cx: Context, place: Place): t.Expression | t.JSXText {
 }
 
 function convertIdentifier(identifier: Identifier): t.Identifier {
-  CompilerError.invariant(identifier.name !== null, {
-    reason: `Expected temporaries to be promoted to named identifiers in an earlier pass`,
-    loc: GeneratedSource,
-    description: `identifier ${identifier.id} is unnamed`,
-    suggestions: null,
-  });
+  CompilerError.invariant(
+    identifier.name !== null && identifier.name.kind === "named",
+    {
+      reason: `Expected temporaries to be promoted to named identifiers in an earlier pass`,
+      loc: GeneratedSource,
+      description: `identifier ${identifier.id} is unnamed`,
+      suggestions: null,
+    }
+  );
   return t.identifier(identifier.name.value);
 }
diff --git a/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.expect.md b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.expect.md
new file mode 100644
index 0000000000..b9e0184b64
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.expect.md
@@ -0,0 +1,25 @@
+
+## Input
+
+```javascript
+function Component(props) {
+  const callback = () => {
+    try {
+      return [];
+    } catch (e) {
+      return;
+    }
+  };
+  return callback();
+}
+
+```
+
+
+## Error
+
+```
+[ReactForget] Invariant: Expected temporaries to be promoted to named identifiers in an earlier pass. identifier 16 is unnamed
+```
+          
+      
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.js b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.js
new file mode 100644
index 0000000000..69c394c826
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.todo-try-catch-within-function-expression.js
@@ -0,0 +1,10 @@
+function Component(props) {
+  const callback = () => {
+    try {
+      return [];
+    } catch (e) {
+      return;
+    }
+  };
+  return callback();
+}