c++ - ADL，普通查找和依赖函数调用不起作用oO

Question

这里给出了简单的代码，它应该根据 C++ 标准工作我相信:

template<typename T> 
void foo(T x) 
{ 
    bar(x); 
    void bar(int);
} 
 
void bar(int)  { } 
 
int main() 
{ 
    foo(0); 
} 

错误来自 GCC 4.7:

‘bar’ was not declared in this scope, and no declarations were foundby argument-dependent lookup at the point of instantiation

但在 C++ 标准中是这样写的。 § 14.6.4.2:

For a function call that depends on a template parameter, thecandidate functions are found using the usual lookup rules (3.4.1,3.4.2, 3.4.3) except that:

— For the part of the lookup using unqualified name lookup (3.4.1) or qualified name lookup (3.4.3), only function declarations from the template definition context are found.

可能是我看错了，谁能指正一下？

Answer 1

您应该将“bar”的声明移到顶部。因为在模板被定义(未实例化)的地方，在调用“bar”之前，它还没有被声明。