[Bug c++/14779] New: the copy constructor for a templatized class is not used in array initialization unless the constructor was previously referenced

[jonathanu at apptechsys dot com]

The copy constructor for a templatized class is not used for struct or array
initialization unless the copy constructor has already been instantiated.

The following code compiles cleanly. However, the copy operator for std::pair is
not used in the std::pair array initialization, causing internal member pointers
to be incorrectly initialized.

If the noted line is uncommented, the copy constructor will be used.

/* Demonstration of a bug with struct and array initialization
 * when using an object with templatized copy constructor.
 */

#include <iostream>
#include <utility>

class show_bug
{
public:
	show_bug () : m_ptr (this) {}
	show_bug (const show_bug &sb) : m_ptr (this) {}
	
	show_bug* m_ptr;
};

typedef std::pair<show_bug, show_bug> pair_bug_t;

const show_bug bug_a, bug_b;

/* UNCOMMENT THE LINE BELOW TO FIX THE BUG
 *  This line instantiates the copy constructor for std::pair,
 *  fixing the bug
 */
//const pair_bug_t fix_bug (pair_bug_t (bug_a, bug_b));

const pair_bug_t pba[] = { pair_bug_t (bug_a, bug_b) };


//-----------------------------
int main (int argc, char **argv)
{
	std::cout << "copy constructor called: ";
	std::cout << (pba[0].first.m_ptr == &pba[0].first) << std::endl;
}

-- 
           Summary: the copy constructor for a templatized class is not used
                    in array initialization unless the constructor was
                    previously referenced
           Product: gcc
           Version: 3.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jonathanu at apptechsys dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: gcc (GCC) 3.3.2 20031218 (Gentoo Linux 3.3.2-r5,
                    propolice-3.3-7
  GCC host triplet: gentoo linux, 2.6.3 kernel, dual xeon
GCC target triplet: gentoo linux, 2.6.3 kernel, dual xeon


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14779