Re: Phasing out Dwarf 1?

[Jim Blandy <jimb@redhat.com>]

Kean Johnston <jkj@sco.com> writes:
> > This seems like a poor argument. The availibility and suitability of
> > modern GCC for building GDB does not imply that modern GCC will be
> > suitable for building the application to be debugged.
> 
> I agree. I think phasing out a whole debugging format
> is ill-advised. Most people dont want to keep around
> multiple versions of a tool. If I need to debug an
> old binary becuase the libc I replaced today is breaking
> something, I think I have a reasonable expectation of
> being able to do so. I think it is quite appropriate to
> phase out the *generation* of said format, but not its
> interpretation in a debugger.

You're assuming it's basically free to keep Dwarf 1 support in GDB.  I
don't think that's the case.

If someone wants to work on the interfaces the debug readers use to
the format-independent portion of GDB, then the Dwarf 1 reader is one
more client of those interfaces to take into account.

If you look in the ChangeLogs, you can see that dwarfread.c continues
to require periodic tweaks.  But these are almost all mechanical
changes that somebody found by 'grep', or things the compiler caught.
How many bugs have been introduced by semantic shifts elsewhere in GDB
that the compiler has been unable to detect?  I'll bet there are a
lot.  In these circumstances, it seems like wishful thinking to say
that GDB supports Dwarf 1.

I would be happy if either:

- a volunteer were to adopt the Dwarf 1 reader, test it regularly
  against any compiler (GCC or otherwise), and work on reducing the
  number of test suite failures it has over the more actively
  maintained readers, or

- we were to delete the Dwarf 1 reader, and make it that much easier
  for people to do symtab work.

But to leave the code there, with no active volunteers to keep it
useful, is the worst of both worlds.