From cf8209ffc07a5a5ad0c3a82dd35ddc368c30a9f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ralph=20K=C3=BCpper?= <ralph@skelpo.com>
Date: Mon, 21 Sep 2026 11:16:01 +0200
Subject: [PATCH] fix(compile): retain classes using multiline var bindings

---
 changelog.d/10660-cjs-multiline-var-hoist.md  |  1 +
 .../compile/cjs_wrap/hoist_classes.rs         | 13 +++++++--
 .../compile/cjs_wrap/tests/hoist_scanner.rs   | 28 +++++++++++++++++++
 3 files changed, 39 insertions(+), 3 deletions(-)
 create mode 100644 changelog.d/10660-cjs-multiline-var-hoist.md

diff --git a/changelog.d/10660-cjs-multiline-var-hoist.md b/changelog.d/10660-cjs-multiline-var-hoist.md
new file mode 100644
index 0000000000..e62ecb1be0
--- /dev/null
+++ b/changelog.d/10660-cjs-multiline-var-hoist.md
@@ -0,0 +1 @@
+- Fixed CommonJS class hoisting when a comma-separated `var` declaration continues across lines. Classes such as Redis's `RedisClient` now remain inside their module factory when they capture private-field helper variables declared on later lines, preserving the initialized helper bindings at runtime. (#10660)
diff --git a/crates/perry/src/commands/compile/cjs_wrap/hoist_classes.rs b/crates/perry/src/commands/compile/cjs_wrap/hoist_classes.rs
index a746bf5254..05a765e71c 100644
--- a/crates/perry/src/commands/compile/cjs_wrap/hoist_classes.rs
+++ b/crates/perry/src/commands/compile/cjs_wrap/hoist_classes.rs
@@ -808,9 +808,10 @@ fn collect_top_level_let_const_var_names(source: &str) -> Vec<String> {
             continue;
         };
         let mut q = p + kw_len;
-        // Walk through one or more comma-separated declarators on the same
-        // logical line. Stop at `=` (initializer), `;`, or the end of line
-        // (semicolon optional in JS).
+        // Walk through one or more comma-separated declarators. A comma may
+        // continue the declaration onto another physical line (as emitted by
+        // TypeScript for long lists of private-field helpers). Otherwise a
+        // top-level newline ends an ASI-terminated declaration.
         loop {
             while q < bytes.len() && (bytes[q] == b' ' || bytes[q] == b'\t') {
                 q += 1;
@@ -874,6 +875,12 @@ fn collect_top_level_let_const_var_names(source: &str) -> Vec<String> {
                     }
                     b',' if inner == 0 => {
                         q += 1;
+                        // A top-level comma proves that another declarator
+                        // follows, so newlines here are continuation
+                        // whitespace rather than ASI boundaries.
+                        while q < bytes.len() && bytes[q].is_ascii_whitespace() {
+                            q += 1;
+                        }
                         break;
                     }
                     b';' | b'\n' if inner == 0 => {
diff --git a/crates/perry/src/commands/compile/cjs_wrap/tests/hoist_scanner.rs b/crates/perry/src/commands/compile/cjs_wrap/tests/hoist_scanner.rs
index 169b82c9bd..7bf6e63999 100644
--- a/crates/perry/src/commands/compile/cjs_wrap/tests/hoist_scanner.rs
+++ b/crates/perry/src/commands/compile/cjs_wrap/tests/hoist_scanner.rs
@@ -29,3 +29,31 @@ module.exports = { ChecksumStream };
         "the class declaration must remain at its source position inside the factory"
     );
 }
+
+#[test]
+fn multiline_var_declarator_keeps_dependent_class_in_cjs_iife() {
+    // @redis/client declares its transpiled private-field helpers as one long
+    // comma-separated `var` statement. The later helpers start on new lines;
+    // missing them here hoists RedisClient out of the CommonJS factory and
+    // severs the class methods' captures of those helper functions.
+    let src = r#"var _RedisClient_instances, _a,
+    _RedisClient_options,
+    _RedisClient_isolationPool,
+    _RedisClient_init;
+class RedisClient {
+    connect() { return _RedisClient_isolationPool(this); }
+}
+_RedisClient_isolationPool = function _RedisClient_isolationPool() {};
+module.exports = { RedisClient };
+"#;
+
+    let (blocks, hoisted_names, rest) = extract_top_level_class_decls(src);
+    assert!(
+        !hoisted_names.iter().any(|name| name == "RedisClient"),
+        "a class depending on a continued CJS-local declaration must not hoist; hoisted block:\n{blocks}"
+    );
+    assert!(
+        rest.contains("class RedisClient"),
+        "the dependent class must remain inside the CommonJS factory"
+    );
+}