C++ 17 full-expression standard definition
问题 This paragraph from the C++ 17 standard draft states, among others, that: A full-expression is: -an unevaluated operand, -a constant-expression ([expr.const]), -an init-declarator ([dcl.decl]) or a mem-initializer ([class.base.init]), including the constituent expressions of the initializer, -an invocation of a destructor generated at the end of the lifetime of an object other than a temporary object, or -an expression that is not a subexpression of another expression and that is not