https://en.cppreference.com/w/cpp/language/structured_binding Structured binding declaration (since C++17) - cppreference.com Binds the specified names to subobjects or elements of the initializer. Like a reference, a structured binding is an alias to an existing object. Unlike a reference, a structured binding does not have to be of a reference type. attr(optional) cv-auto ref-q en.cppreference..