crates/vm/src/builtins/str.rs (1)

1044-1059: LGTM! Correct fix for Unicode multi-character case expansions.

The change from to_ascii_uppercase()/to_ascii_lowercase() to to_uppercase()/to_lowercase() with extend() properly handles Unicode case mappings that expand to multiple characters (e.g., "ß" → "SS", or "ı" → "I"). The shrink_to_fit() call is appropriate since the initial capacity may over-allocate for potential expansions that don't always occur.

Minor terminology nit: the comment at line 1048 says "multiple bytes" but technically to_uppercase() returns an iterator because case changes may produce multiple characters (code points), not bytes. Each character is then encoded to its byte representation.

📝 Optional comment clarification

-            // to_uppercase returns an iterator because case changes may be multiple bytes
+            // to_uppercase returns an iterator because case changes may produce multiple characters

,

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@crates/vm/src/builtins/str.rs` around lines 1044 - 1059, Update the inline
comment inside the swapcase method to accurately describe why
to_uppercase()/to_lowercase() return an iterator: change "multiple bytes" to
"multiple characters (code points)" or similar; the correction should be made in
the comment immediately above the if-block that calls c.to_uppercase() and
c.to_lowercase() in the swapcase function (referencing swapcase, c_orig,
to_uppercase, to_lowercase).