“complete-class context - a semantic region within the lexical scope of a class definition in which the class (as a whole) itself is considered to be a complete type — e.g., function bodies, default arguments, default member initializers (see Section 2.1.“Default Member Init” on page 318), and noexcept specifiers (see Section 3.1.“noexcept Specifier” on page 1085). Default Member Init (319), noexcept Specifier (1086)” (EMCppSfe 2021)