Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
303 views
in Technique[技术] by (71.8m points)

c++ - Does attribute specifier sequence inherit?

Look at this snippet:

struct [[nodiscard]] Result {
};


struct DiscardableResult: Result {
};

Does DiscardableResult have the [[nodiscard]] attribute? If yes, is it possible to remove it somehow?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

[dcl.attr.nodiscard]/2 says:

A nodiscard call is a function call expression that calls a function previously declared nodiscard, or whose return type is a possibly cv-qualified class or enumeration type marked nodiscard.

The return type of the function is DiscardableResult. This type is not marked nodiscard, as defined in [dcl.attr.grammar]/5:

Each attribute-specifier-seq is said to appertain to some entity or statement, identified by the syntactic context where it appears (Clause 9, Clause 10, Clause 11). If an attribute-specifier-seq that appertains to some entity or statement contains an attribute or alignment-specifier that is not allowed to apply to that entity or statement, the program is ill-formed. If an attribute-specifier-seq appertains to a friend declaration (14.3), that declaration shall be a definition. No attribute-specifier-seq shall appertain to an explicit instantiation (17.7.2).

Emphasis added.

There is no attribute in the "syntactic context" of DiscardableResult. Therefore, no attribute "appertains" to this entity.

Attributes are not inherited.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...