I've got following code:
File: Foo.h
class Foo {
friend void Bar();
};
File: Foo.cpp
void Bar() {};
File Test.cpp
#include "Foo.h"
int main(void) {
Bar();
return 0;
}
VS2008 compiles this without any error or warning. G++ 4.3.4 reports:
test.cpp: In function ‘int main()’:
test.cpp:8: error: ‘Bar’ was not declared in this scope
Why?
I found this question in the "unanswered" section, but the comments to the previous incorrect answer do constitute a correct answer. Therefore here is a community wiki response with that content.
Summary: GCC appears to be rejecting good code.
case when a friend function is defined (not only declared) inside class is covered by 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, the function name is unqualified, and the function has namespace scope" -- your example fulfils these requirements). I guess that standard does allow declaration ("prototype") of a friend function inside class. It is the error g++ is generating which bothers me. – liori Nov 22 at 20:35
Also 11.4.3: "A function first declared in a friend declaration has external linkage (3.5). Otherwise, the function retains its previous linkage (7.1.1)." I think that seals the deal. – Potatoswatter 0 secs ago [delete this comment]
