Somehow I ended using an old version of XCode :( switched to XCode 16 and made sure I was targeting iOS 18, that fixed it

Hey there, Thanks for checking that for me. It's encouraging to hear that it compiles. I renamed the variable c to something more unique, but the compilation bug described above persisted. I also did a clean build and tried restarting XCode, but the problem still persists. What's odd is that some of the other functionality for the Entity.ComponentSet, such as set() or removeAll() compiles with no issue. The compiler just doesn't see the Sequence conformance for the for-in loop.