c++ - 如何在仍然允许 ADL 等的情况下调用同名的其他函数

Question

如何在第二个 f() 中进行调用，通过非限定查找找到第一个 f()，以便 ADL 和普通名称查找规则仍然有效？

注意:我不想更改任何函数的名称。

namespace x 
{
    void f()
    {
    }

    class C 
    {
        void f() 
        {
            x::f();
        }
    };
}

Answer 1

只需引入函数:

void f()
{
    using x::f;
    f(); // calls x::f()
}

这样做的原因是，复制 Mike Seymour's answer :

Because the using declaration brings x::f into the scope of f, which is narrower than that of C. Unqualified lookup considers the local block scope, finds a match, and stops before considering the wider class scope. There is no argument-dependent lookup since there are no function arguments, so no further scopes are considered.