Re: ada loops

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Pascal Obry <p.obry@wanadoo.fr> writes:

> Robert A Duff <bobduff@shell01.TheWorld.com> writes:
> 
> > There is no version of gdb that is Ada aware.
> 
> This is of course plain wrong !

I was being somewhat sarcastic.  ;-)

Of course I am well aware of the version of gdb distributed with GNAT,
and I use it.  However, almost every time I use it in any serious way,
it shows some confusion about Ada.  For example, it thinks a parameter
of type String is actually of type pointer-to-String.  Often, it can't
find objects that are (or should be) visible -- I'm not sure exactly
what's going on, but I think it is confused about nested block
statements, and nested procedures.  Another example is that it often
crashes when I try to call a procedure with anything but the simplest of
parameter types.

Calling procedures is a very useful feature of any debugger -- it allows
you to print out data stuctures in a higher-level form than a plain
listing of record fields and whatnot.  But it only works half the
time, in my experience.

Another example: I have a generic package that is instantiated 20 times,
and I want to call one of the procedures.  Gdb will then ask me which of
the 20 I meant.  If it were truly Ada aware, it would know which one,
based on the types of the actual parameters -- that's what the compiler
knows how to do.

The OP complained that gdb did something obviously wrong, and somebody
responded saying it must be caused either by a bug in the Ada program
that destroyed memory, or by using the wrong version of gdb.  That's not
my experience at all; the GNAT version gdb lies to me and/or crashes
quite often, even when there are no memory-destroying bugs around
the place.  (Those bugs are quite rare in Ada, after all, given all the
good array-bounds checking and whatnot.)

So I stand by my claim: There is no version of gdb that is Ada aware.

Gdb is a C debugger.  The GNAT version understands some part of Ada,
and it does improve over time, but it's still got a long way to go
before it understands Ada as well as, say, the GNAT Ada compiler!

Having said all that, I don't use debuggers very heavily.  Usually just
to get a stack traceback for an unhandled exception.  I think it's
usually better to try to understand the code I write, rather than to
throw something together and then spend all day rummaging around in the
debugger to see what's going on.

- Bob