[RFA 1/8] Add gdb_ref_ptr.h

[Tom Tromey]

>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> Can you please remove them and see what breaks?  Odd that this would be
Pedro> something about Python, given the class is being used in Python code
Pedro> today?

Yes, it's odd.  If I comment out the nullptr_t overloads, I get build
failures like:

../../binutils-gdb/gdb/python/py-exitedevent.c:31:20: error: no match for ‘operator==’ (operand types are ‘gdbpy_ref {aka gdb::ref_ptr<_object, gdbpy_ref_policy>}’ and ‘long int’)
   if (exited_event == NULL)
                    ^
../../binutils-gdb/gdb/common/gdb_ref_ptr.h:183:13: note:   template argument deduction/substitution failed:
In file included from ../../binutils-gdb/gdb/python/py-ref.h:23:0,
                 from ../../binutils-gdb/gdb/python/py-event.h:27,
                 from ../../binutils-gdb/gdb/python/py-event.c:21:
../../binutils-gdb/gdb/common/gdb_ref_ptr.h:171:13: note: candidate: template<class T, class POLICY> bool gdb::operator==(const T*, const gdb::ref_ptr<T, POLICY>&)
 inline bool operator== (const T *self, const ref_ptr<T, POLICY> &other)
             ^~~~~~~~


I don't understand why it picks this particular candidate, but
re-reading it now I think my earlier theory is wrong.

Tom