Re: GDB pretty printers for iterators

[Tom Tromey <tromey at redhat dot com>]

Joe> I debug a lot of C++ code with iterators.  For me, it's OK to see
Joe> the internals because I know what they look like, and I'd prefer that
Joe> to any attempt to make things pretty that hides vital information I
Joe> need to fix the bug.  Maybe it's possible to make things pretty *and*
Joe> expose all relevant information, but an iterator is far more than simply
Joe> the value that it points to, so I don't think that just printing
Joe> "-> 2"
Joe> is going to cut it.

We could easily add a new gdb parameter to let you choose whether these
printers are activated.  Something like "set print libstdcxx-iterators off"
(or whatever name you like).

Joe> What I would like is to be able to reliably call the * and ->
Joe> operators on an iterator from the debugger, so that gdb can do the
Joe> same kinds of expressions that appear in source code.  In some
Joe> cases this works today, and in others it doesn't.

If you know when it does not work, that would be handy.

Joe> Having == and != work would be even better, though this is trickier
Joe> because of the need to handle any overloading properly on pairs of
Joe> iterators, conversion between const_iterator and iterator, and
Joe> other nastiness.

We'll get there eventually.  We are slowly chipping away at the
expression evaluation discrepancies between gdb and g++.  We can't
achieve full compatibility, but I think we can get a lot closer than we
are now.

Tom