Re: [PATCHv2 1/2] gdb: fix 'list' for multiple source file results

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 4 Dec 2025 13:18:35 -0700
> From: Kevin Buettner <kevinb@redhat.com>
> Cc: gdb-patches@sourceware.org
> 
> On Wed, 19 Nov 2025 10:32:37 +0000
> Andrew Burgess <aburgess@redhat.com> wrote:
> 
> > From: Andrew Burgess <aburgess@redhat.com>
> > To: gdb-patches@sourceware.org
> > Cc: Andrew Burgess <aburgess@redhat.com>
> > Subject: [PATCHv2 1/2] gdb: fix 'list' for multiple source file results
> > Date: Wed, 19 Nov 2025 10:32:37 +0000
> > 
> > This commit:
> > 
> >   commit c7a45b98a61451f05ff654c4fb72a9c9cb2fba36
> >   Date:   Thu Jun 12 15:37:50 2025 +0000
> > 
> >       gdb, linespec: avoid multiple locations with same PC
> > 
> > broke GDB's ability to list multiple source files using a 'list'
> > command.  In GDB 16 and earlier something like 'list foo.c:10' could
> > print multiple results if there were multiple 'foo.c' files compiled
> > into the executable.
> > 
> > The above commit added a filter to add_sal_to_sals (linespec.c) such
> > that multiple sals in the same program space, but with the same pc
> > value, could not be added, only the first sal would actually be
> > recorded.  The problem with this is that add_sal_to_sals is used from
> > decode_digits_list_mode (also linespec.c) where the pc value is forced
> > to zero.  This force to zero makes sense I think as there might not be
> > any compiled code for the requested line (this is for 'list' after
> > all), so there might not be a valid pc to use.
> > 
> > I'm not a fan of using '0' as a special pc value, there are embedded
> > targets where 0 is a valid pc value, but given we're already using 0
> > here, I propose to just roll with it.
> > 
> > So, my proposal is that, if the pc is 0, add_sal_to_sals should always
> > add the sal.  This fixes the decode_digits_list_mode, but should keep
> > the fix that c7a45b98a614 introduced.
> > 
> > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33647
> > ---
> >  gdb/linespec.c                               |  15 ++-
> >  gdb/testsuite/gdb.base/list-multi-source.c   |  60 +++++++++
> >  gdb/testsuite/gdb.base/list-multi-source.exp | 129 +++++++++++++++++++
> >  3 files changed, 199 insertions(+), 5 deletions(-)
> >  create mode 100644 gdb/testsuite/gdb.base/list-multi-source.c
> >  create mode 100644 gdb/testsuite/gdb.base/list-multi-source.exp
> 
> LGTM, also.  I, too, think it should go into 17.

I agree that the fix should go into GDB 17, because otherwise it will
be a bad regression.