Is a friend function defined in-class automatically inline?
If a member function is defined inside the class, it is an inline function. E.g.
struct X
{
void mem_f() {} //mem_f is inline
};
My question is whether a nonmember friend function defined inside the class is also automati开发者_Go百科cally inline.
E.g.
struct Y
{
friend void friend_f() {} //is friend_f inline?
};
A relevant quote/paragraph_no from the standard would be much welcome. Thanks.
Yes, it is. §11.4/5:
A function can be defined in a friend declaration of a class if and only if the class is a non-local class (9.8), the function name is unqualified, and the function has namespace scope. Such a function is implicitly inline. A friend function defined in a class is in the (lexical) scope of the class in which it is defined. A friend function defined outside the class is not (3.4.1).
Since the class definition is presumably in a header file, the function will be multiply-defined, so it needs to be inline
.
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