namespaces are ignored on template template parameters by Krishty

Closed

as Deferred Help for as Deferred

Type:	Bug
ID:	778488
Opened:	2/4/2013 11:15:45 AM
Access Restriction:	Public

Workaround(s)

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User(s) can reproduce this bug

With template template parameters, Visual C++ fails to determine the correct type if two or more parameters have the same class name, but from different namespaces. It seems like only the very last fraction of the class name is considered.

Details (expand)

Visual Studio 2012

namespace Namespace1 {

    template <typename T>
    struct SameName { };

}

namespace Namespace2 {

    template <typename T>
    struct SameName {
        static void foo() { }
    };

}

template <
    template <typename> class SameName1,
    template <typename> class SameName2
> struct Foo
    : SameName1<void>, SameName2<void>
{
    static void hellBreaksLoose() {
        SameName2<void>::foo();
    }

};

void main() {
    Foo<Namespace1::SameName, Namespace2::SameName>::hellBreaksLoose();
}

English

Windows 7 SP1

English

error C2387: 'SameName<void>' : ambiguous base class
error C2039: 'foo' : is not a member of 'Namespace1::SameName<T>'

i.e., compiler confused about whether SameName<void> from Namespace1 or Namespace2 is to be used

successful build, because the template parameter name is absolutely unambigous

this can be achieved by
1) renaming the base classes to different names (but that's why C++ has namespaces in the first place!); or
2) typedef'ing the template parameters and using these typedef's to access base class functions

0 attachments

Posted by Microsoft on 2/4/2013 at 9:55 PM

Thanks for your feedback.

We are rerouting this issue to the appropriate group within the Visual Studio Product Team for triage and resolution. These specialized experts will follow-up with your issue.

Posted by Microsoft on 2/4/2013 at 11:51 AM

Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com)

Microsoft