https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86392
Bug ID: 86392
Summary: templatized friend member function needs declaration
Product: gcc
Version: 8.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rene.r...@fu-berlin.de
Target Milestone: ---
Hi, I need some help to understand the following behaviour.
I have a class with a friend get<pos|type> function which implements the
behaviour of std::get. However, the compiler can't find the get function in my
namespace unless I either declare some global function template with the name
get. But it does not even have to match the friend's declaration, as long as
the name is declared once in the namespace or I made with using std::get some
get visible in the context.
Now, I was wondering why for such a template function ADL doesn't work.
Note that it works without out-of-class declaration if the friend template
function uses all it's template parameters as arguments.
So for example:
template <typename t>
class foo
{
template <typename _t>
friend auto bar(_t && a, foo && b) { ... }
};
would work and the compiler will find bar(3, foo{});
The same behaviour happens with clang, so I think I am just missing something
here and I would appreciate a short explanation.
Sorry for bothering you with probably such simple concerns.
