使用保留标识符时，using命令应该发出警告吗? [英] Should a using command issue a warning when using a reserved identifier?

问题描述

使用线路时

using std::literals::chrono_literals::operator""s;

在g ++ 6.3.0中，编译器发出警告，指出:

in g++ 6.3.0, the compiler issues a warning stating:

警告:保留不带'_'的文字运算符后缀以供将来标准化

warning: literal operator suffixes not preceded by '_' are reserved for future standardization

using std::literals::chrono_literals::operator""s;

在MSVS中也发出了类似的警告.但是，clang 3.8.0不会发出此类警告.

A similar warning is also issued in MSVS. However, clang 3.8.0 issues no such warning.

由于operator""s是由chrono库的标准定义的，因此不应该发出警告，因为我们只是导入名称而未定义名称吗?

Since operator""s is defined by the standard for the chrono library shouldn't this not issue a warning since we are just importing the name and not defining one?

推荐答案

可以说，在此

一些文字后缀标识符是 为将来的标准化保留；参见17.6.4.3.5.声明其 literal-operator-id 使用这样的文字后缀 标识符格式错误；无需诊断.

Some literal suffix identifiers are reserved for future standardization; see 17.6.4.3.5. A declaration whose literal-operator-id uses such a literal suffix identifier is ill-formed; no diagnostic required.

这可以解释为是指(UDL运算符)声明，其名称"是 literal-operator-id —当然排除了您的情况，因为 literal-operator- ID 是不合格的. [reserved.names]/2 也是如此，其中上下文是用户定义的文字运算符的声明.

This can be interpreted as referring to (UDL operator) declarations whose "name" is a literal-operator-id—which of course excludes your case, since literal-operator-ids are unqualified. Same goes for [reserved.names]/2, where the “context”s are declarations of user-defined literal operators.

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