Comma

When you write x, y in generic code, most of the time you intend that to mean “evaluate x, then evaluate y and make that the result”. But since operator, can be overloaded, this could end up meaning something else entirely.

A simple workaround is to stick a void() in between the two expressions:

x, void(), y

Since you can’t take a void parameter, there’s no way for this to result in a call to an overloaded operator,.