[Bug c++/45002] New: Name of member class of template class cannot be used as argument type.

[walton at seas dot harvard dot edu]

The name of a member class of a template class is NOT recognized
as an argument type in a template function.  This makes such member
classes largely unusable.

The same applies to an attempt to workaround using typedefs inside
the template class.  The error may be in syntax analysis.

Example is below:

Bob Walton
wal...@seas.harvard.edu
Tue Jul 20 06:22:02 EDT 2010

g++ --version output:
--------------------

g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Code: template-member-class-bug.cc
----------------------------------

# include <iostream>
using namespace std;

template < typename T >
class A;

template < typename T >
class B
{
public:

    class C;

    typedef A<T> D;
    friend class A<T>;
};

// These are OK:

    template < typename T >
    void funcAvoid ( A<T> * a );

    template < typename T >
    int funcAint ( A<T> * a );

    template < typename T >
    void funcBvoid ( B<T> * b );

    template < typename T >
    int funcBint ( B<T> * b );

// These incorrectly fail:

    template < typename T >
    void funcCvoid ( B<T>::C * c );

    template < typename T >
    int funcCint ( B<T>::C * c );

    template < typename T >
    void funcDvoid ( B<T>::D * d );

    template < typename T >
    int funcDint ( B<T>::D * d );

// The following checks the non-template version:

class E;
class F
{
public:
    class G;
};

// These non-template versions are OK:

    void funcGvoid ( F::G * g );
    int funcGint ( F::G * g );

int main ()
{
    cout << "HELLO" << endl;
}

g++ output:
----------

template-member-class-bug.cc:35: error: variable or field ‘funcCvoid’ declared
void
template-member-class-bug.cc:35: error: template declaration of ‘int funcCvoid’
template-member-class-bug.cc:35: error: ‘c’ was not declared in this scope
template-member-class-bug.cc:38: error: template declaration of ‘int funcCint’
template-member-class-bug.cc:38: error: ‘c’ was not declared in this scope
template-member-class-bug.cc:41: error: variable or field ‘funcDvoid’ declared
void
template-member-class-bug.cc:41: error: template declaration of ‘int funcDvoid’
template-member-class-bug.cc:41: error: ‘d’ was not declared in this scope
template-member-class-bug.cc:44: error: template declaration of ‘int funcDint’
template-member-class-bug.cc:44: error: ‘d’ was not declared in this scope


-- 
           Summary: Name of member class of template class cannot be used as
                    argument type.
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: walton at seas dot harvard dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45002