From ac737a1ac59680dbe497bda1eaea1c02f80b4983 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Andr=C3=A9=20Bargull?= <andre.bargull@gmail.com>
Date: Wed, 27 Mar 2024 07:35:40 +0000
Subject: [PATCH] Bug 1887677: Correctly compute inClass predicate when
 validating unbound private names. r=dminor

`SharedContext::inClass()` returns whether the current `SharedContext` is within
a class definition. A class definition itself doesn't create a new `SharedContext`,
so an inner nested class definition within a computed property key of an outer
class definition was treated as if it wasn't nested within a class definition. This
led to reporting a SyntaxError when checking for unbound private names.

Calling `ParseContext::findInnermostStatement()` in addition to `SharedContext::inClass()`
fixes this issue. (We need to keep `SharedContext::inClass()` to correctly handle
lazily parsed classes.)

Differential Revision: https://phabricator.services.mozilla.com/D205609
---
 js/src/frontend/Parser.cpp                              |  6 +++++-
 .../nested-class-in-computed-property-key.js            | 17 +++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 js/src/tests/non262/PrivateName/nested-class-in-computed-property-key.js

diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index eca2c0f35d30..bb5ad66fb16d 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -8006,7 +8006,11 @@ GeneralParser<ParseHandler, Unit>::classDefinition(
   // position in order to provide it for the nodes created later.
   TokenPos namePos = pos();
 
-  bool isInClass = pc_->sc()->inClass();
+  auto isClass = [](ParseContext::Statement* stmt) {
+    return stmt->kind() == StatementKind::Class;
+  };
+
+  bool isInClass = pc_->sc()->inClass() || pc_->findInnermostStatement(isClass);
 
   // Push a ParseContext::ClassStatement to keep track of the constructor
   // funbox.
diff --git a/js/src/tests/non262/PrivateName/nested-class-in-computed-property-key.js b/js/src/tests/non262/PrivateName/nested-class-in-computed-property-key.js
new file mode 100644
index 000000000000..7596dfe5428e
--- /dev/null
+++ b/js/src/tests/non262/PrivateName/nested-class-in-computed-property-key.js
@@ -0,0 +1,17 @@
+let capturedPrivateAccess;
+class A {
+  // Declare private name in outer class.
+  static #x = 42;
+
+  static [(
+    // Inner class in computed property key.
+    class {},
+
+    // Access to private name from outer class.
+    capturedPrivateAccess = () => A.#x
+  )];
+}
+assertEq(capturedPrivateAccess(), 42);
+
+if (typeof reportCompare === 'function')
+  reportCompare(0, 0);
-- 
2.11.4.GIT