[PATCH] gdb, btrace: Throw an error for empty recordings when replaying starts.

[Willgerodt, Felix]

> -----Original Message-----
> From: Andrew Burgess <aburgess@redhat.com>
> Sent: Mittwoch, 11. Mai 2022 11:34
> To: Willgerodt, Felix <felix.willgerodt@intel.com>; Metzger, Markus T
> <markus.t.metzger@intel.com>; gdb-patches@sourceware.org
> Subject: Re: [PATCH] gdb, btrace: Throw an error for empty recordings when
> replaying starts.
> 
> Felix Willgerodt via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> > This makes record_btrace_start_replaying() more consistent, as it already
> > errors out e.g. on a recording with only gaps.
> > ---
> >  gdb/record-btrace.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
> > index 373d82b8b99..3f8a69dd04f 100644
> > --- a/gdb/record-btrace.c
> > +++ b/gdb/record-btrace.c
> > @@ -2017,7 +2017,7 @@ record_btrace_start_replaying (struct
> thread_info *tp)
> >
> >    /* We can't start replaying without trace.  */
> >    if (btinfo->functions.empty ())
> > -    return NULL;
> > +    error (_("No trace."));
> >
> >    /* GDB stores the current frame_id when stepping in order to detects
> steps
> >       into subroutines.
> 
> Please can you add a test for this change.
> 
> Thanks,
> Andrew

Mhm, I don't think there is an actual test I can write to trigger this.
All callers prevent it from happening by checking btinfo->replay.
I am just making it more consistent, as the function already
errors out in the case of just gaps. Another advantage is that this function
doesn't return NULL anymore, which seems better for future callers.

Thanks,
Felix
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