Re: [lmi] LLVM libc++

[Greg Chicares]

On 10/6/22 21:10, Vadim Zeitlin wrote:
> On Thu, 6 Oct 2022 18:52:15 +0000 Greg Chicares <gchicares@sbcglobal.net> 
> wrote:
> 
> GC> If you'd like to propose a replacement for lmi's 'unwind.?pp',
> GC> I'd welcome that. I have no reason to prefer libunwind. I just
> GC> want exception backtraces.
> 
>  I think relying on libunwind is a nuisance, so I'd like to get rid of it.
> We probably still want to use libdw as getting source information without
> it isn't simple, i.e. in wxWidgets I do it by running addr2line which is
> much slower (and also doesn't work correctly right now, but I'm working on
> fixing that).

My attempts to use addr2line in the past have been arduous and
ultimately not fully satisfactory. But that was long ago.

>  But it actually depends on what kind of information do you need to have in
> the backtraces: if only function names are enough, then backtrace_symbols()
> is all you need and is by far the simplest solution. If you do want the
> file names and line numbers too,

Yes, those things are extremely important to me. Without them,
I'd have to go back to inserting
  std::cout << __FILE__ << ' ' << __LINE__ << std::endl;
throughout the code in order to localize a problem.

> then either libdw or libbfd or libdwarf
> are needed in practice (in theory it would be possible to do what these
> libraries do in lmi's own code, but this doesn't seem like a good idea).
> 
>  So how important are the line numbers in the backtraces?
Extremely important.