cpp/language/attributes/maybe unused

Suppresses warnings on unused entities.

Explanation
This attribute can appear in the declaration of the following entities:


 * class/struct/union: ,
 * typedef, including those declared by alias declaration:, ,
 * variable, including static data member: ,
 * non-static data member: ,
 * function: ,
 * enumeration: ,
 * enumerator: ,
 * structured binding:.

For entities declared, if the entities or their structured bindings are unused, the warning on unused entities issued by the compiler is suppressed.