Re: RFC c++ debugging thread (fwd)

[Jim Blandy <jimb at zwingli dot cygnus dot com>]

Hi, Carlo.  Ben Kosnik forwarded your message to me.  I've taken the
liberty of CC'ing the GDB discussion mailing list on this reply; hope
that's okay.

> ---------- Forwarded message ----------
> Date: Sat, 30 Jun 2001 17:44:03 +0200
> From: 
> To: Benjamin Kosnik <bkoz@redhat.com>
> Cc: libstdc++@gcc.gnu.org
> Subject: Re: RFC c++ debugging thread
> 
> On Fri, Jun 29, 2001 at 12:00:34PM -0700, Benjamin Kosnik wrote:
> > 
> > Hey C++ people. The gdb folks are doing inventory on C++ support in
> > the debugger. People who use gdb with C++ should probably scope this
> > thread and add constructive comments:
> > 
> > http://sources.redhat.com/ml/gdb/2001-06/msg00219.html
> > 
> > -benjamin
> 
> If you can pass this on:
> 
> 1) When typing expressions that have a scope, it is extremely annoying that the current
>    scope is often not known to gdb - especially the lack of namespace support is annoying.
>    I am using anonymous namespaces frequently and that makes it impossible to set
>    break-points other than by line number.
>    I think that when gdb is in a function 'A::(unamed)::C::f()', and I ask for 'g()', it should
>    use the same lookup as the compiler: "(gdb) b g" should set a break point in the same
>    function as that is called when I'd have had: "void A::(unnamed)::C::f(void) { g(); }".
>    The ideal situation being that using an expression that appears after a 'list' command
>    of the current scope will resolve to the correct expression.  Another example being
>    that in my current project ALL code that I am debugging is in namespace 'libcw::debug',
>    so why do I constantly have to type: b 'libcw::debug::foo'?  I'd like to just type:
>    "(gdb) b foo" (assuming the current code is in scope 'libcw::debug' thus).

Our current understanding is that the namespace lossage is the most
immediately annoying problem, so that's what we'd like to fix first.

We have test cases for some problems, and although your problem sounds
similar, I can't be sure it's exactly the same problem you are seeing.
Could you put together a test case, show us what GDB does, and tell us
what you wish it did?  Post to gdb@sources.redhat.com.

> 2) The 'next' command often doesn't work: it just finishes the whole program.  I therefore
>    have to use 'step' more often then I like, resulting in entering functions I don't
>    want to enter (like libstdc++/STL stuff).  I don't know why/when this happens, but
>    it seems to happen often when returning from a function (on a '}' of a function that
>    I am exiting, I *always* type 's' to avoid losing the trace).
> 3) Often wrong source-file:line-numbers are given.  This might be a bug in the compiler.
> 4) Not all mangled names are demangled, and obviously the qualifiers are demangled wrongly,
>    assuming you use libiberty's demangler then I suppose this will be fixed.  I'll get back
>    to this after my own demangler finally works (I am working on getting adding of
>    substitutions right now).

Again, these sound like something we know about, but I'm not sure.  If
you can provide a test case, that makes it much easier for us to be
sure we've actually fixed what's bothering you.