“comma operator - (1) the built-in sequencing operator that evaluates and discards the result of its left-hand side expression and then unconditionally evaluates its right-hand side expression, which becomes the result of evaluating the operator or (2) an overloaded operator, having the name operator,, that unconditionally evaluates both of its arguments and returns a result as determined by its user-provided definition. constexpr Functions (268)” (EMCppSfe 2021)