Possible bug in list::size()? Or my misreading?

[Brad Spencer <spencer at infointeractive dot com>]

While I was debugging today, I ended up looking at the definition of
list::size(), initially on 2.95.3.  I was concerned by what I saw, so
I checked 3.0.3 with libstdc++-v3.0.95, but found (roughly) the same thing:

   size_type
   size() const
   { return distance(begin(), end()); }

Please tell me I've just misunderstood this all these years, but my
copy of the standard says, in Section 23.1, Table 65:

  Those entries marked "(Note A)" should have constant complexity.

Sure enough, size() is marked with "(Note A)".  However, the trivial
program below is enough to show that this is not the case and list
computes its size in O(n) with each call to size!  What have I missed?

The program:

#include <list>
#include <iostream>

int
main()
{
  std::list<int> li;

  for(unsigned int i = 0; i < 10000; i++) {
    li.push_back(i);
  }
  std::cout << li.size() << std::endl;
}

And a snippet from my gdb session, in which I traced it into the
InputIterator version of distance, as expected:

(gdb) l stl_iterator_base_funcs.h:116
111         {
112           // concept requirements
113
__glibcpp_function_requires(_InputIteratorConcept<_InputIterator>)
114           typename
iterator_traits<_InputIterator>::difference_type __n = 0;
115           while (__first != __last) {
116             ++__first; ++__n;
117           }
118           return __n;
119         }
120
(gdb) info break 2
Num Type           Disp Enb Address    What
2   breakpoint     keep y   0x0804a644 in
__distance<std::_List_iterator<int, const int&, const int*> >
                                       at
				       stl_iterator_base_funcs.h:116
        breakpoint already hit 10000 times

:(  I can't see anywhere where the list container maintains a count of
the current number of elements, so it looks like this would also be a
non-trivial fix.  I haven't looked in detail at any of the other
containers yet.

Should I file a bug report?
	
-- 
-----------------------------------------------------------------
Brad Spencer - spencer@infointeractive.com - "It's quite nice..."
  Systems Architect | InfoInterActive Corp. | An AOL Company