Function template look-up issue [duplicate]

Question

Could someone please explain why the following code is giving error (error C2065: 'select' : undeclared identifier) at compile time:

namespace N { class MyClass{ }; template<int I> void select(MyClass*) {} } void g (N::MyClass* mp) { select<10>(mp); } void main() {}

According to Argument Dependent Lookup, this should work fine, since I have specified N:: in `g``s argument. So, select should be visible to compiler.

Why does ADL not work here?

btw, it's int main() or int main(int argc, char* argv[]), even if you do not return anything (in which case it is the same as returning 0) — Sebastian Mach
– Sebastian Mach, Commented Oct 25, 2013 at 11:34
"void main()" also works fine. I am working on VS 2008. May i know why have you explicitly mentioned it? It will be helpful for me if its important. Why main should return int? — Anitesh
– Anitesh, Commented Oct 25, 2013 at 12:02
@Anitesh: main should return int because that's the only portable return type specified by the language standard. Your compiler allows non-standard extensions, but most others don't. Posting non-standard code here makes the question harder to answer. — Mike Seymour
– Mike Seymour, Commented Oct 25, 2013 at 12:36

Maggnetix · Accepted Answer · 2013-10-25 11:28:56Z

0

have you tried N::select? either that or a

using namespace N

should work since simply select is not visible

answered Oct 25, 2013 at 11:28

Maggnetix

1349 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Sebastian Mach Over a year ago

you cannot see it yet, but this is the fourth answer that states use N::select. But this is not an answer to the question. The question was about why ADL does not work here.

Anitesh Over a year ago

I got my answer in this link. Please refer.

Community · Accepted Answer · 2017-05-23 10:31:47Z

Any time you utilise a class from a divergent namespace from the one you are currently in you must either reference it directly (N::select) or set up a using namespace (using namespace N;) or set up a direct using statement to it for future use (using N::select)

For disambiguation I would look at this and this , which between them should give you a good start on how/why you cannot simply call select.

Cheers, and feel free to get a hold of me for more info.

Collectives™ on Stack Overflow

Function template look-up issue [duplicate]

2 Answers 2

2 Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Linked

Related