C++1z 中的 §12.3.2 [class.conv.fct]/1 相对于 C++14 发生了重大变化。是否有意义？

Question

§12.3.2 [class.conv.fct]/1 在 C++14 中：

A member function of a class X having no parameters with a name of the form

    conversion-function-id:
       operator conversion-type-id
    conversion-type-id:
       type-specifier-seq conversion-declarator_opt
    conversion-declarator:
       ptr-operator conversion-declarator_opt

specifies a conversion from X to the type specified by the conversion-type-id. Such functions are called conversion functions. No return type can be specified. If a conversion function is a member function, the type of the conversion function (8.3.5) is “function taking no parameter returning conversion-type-id”. ...

§12.3.2 [class.conv.fct]/1 in C++1z：（相关更改在下面突出显示）

A member function of a class X having no parameters with a name of the form

    conversion-function-id:
       operator conversion-type-id
    conversion-type-id:
       type-specifier-seq conversion-declarator_opt
    conversion-declarator:
       ptr-operator conversion-declarator_opt

specifies a conversion from X to the type specified by the conversion-type-id. Such functions are called conversion functions. A decl-specifier in the decl-specifier-seq of a conversion function (if any) shall be neither a defining-type-specifier nor static. Type of the conversion function (8.3.5) is “function taking no parameter returning conversion-type-id”. ...

我想不出没有 decl-specifier-seq 或 decl-specifier-seq 的转换函数不包含 定义类型说明符 。据我所知，这意味着 conversion-function-id，其 conversion-type-id 没有类型！

Answer 1

A conversion-type-id 不包含 decl-specifier-seq；它包含一个 type-specifier-seq。

那句话是关于这个 decl-specifier-seq 在转换函数的 declaration/definition:

struct C {
    constexpr inline explicit operator int() const { return 0; }
//  ^^^^^^^^^^^^^^^^^^^^^^^^^
    operator float() const;
// ^ no decl-specifier-seq here
};

由于显而易见的原因，它不能包含 定义类型说明符。

更改的要点是，当 return 类型由 conversion-type-id 确定时，说 "no return type can be specified" 会产生误导。

C++1z 中的 §12.3.2 [class.conv.fct]/1 相对于 C++14 发生了重大变化。是否有意义？

§12.3.2 [class.conv.fct]/1 in C++1z changed substantially in relation to C++14. Does it make sense?

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