All I can think of is Koenig lookup [1]: B and foo were defined in a namespace, and the calls to foo were not in that namespace and didn't explicitly qualify fo

All I can think of is Koenig lookup [1]: B and foo were defined in a namespace, and the calls to foo were not in that namespace and didn't explicitly qualify foo but still found it. [1] https://en.m.wikipedia.org/wiki/Argument-dependent_name_lookup https://en.m.wikipedia.org/wiki/Argument-dependent_name_look...