Re: [PUSHED 5/6] gdb: use libbacktrace to create a better backtrace for fatal signals

[Simon Marchi <simon.marchi@polymtl.ca>]

> +void
> +gdb_internal_backtrace ()
> +{
> +  if (current_ui == nullptr)
> +    return;
> +
> +  const auto sig_write = [] (const char *msg) -> void
> +  {
> +    gdb_stderr->write_async_safe (msg, strlen (msg));
> +  };
> +
> +  sig_write (_("----- Backtrace -----\n"));
> +
> +  if (gdb_stderr->fd () > -1)
> +    gdb_internal_backtrace_1 ();
> +  else
> +    sig_write (_("Backtrace unavailable\n"));

I happen to try to build GDB on NetBSD, and I get:

      CXX    bt-utils.o
    /home/simark/src/binutils-gdb/gdb/bt-utils.c: In function 'void gdb_internal_backtrace()':
    /home/simark/src/binutils-gdb/gdb/bt-utils.c:165:5: error: 'gdb_internal_backtrace_1' was not declared in this scope
         gdb_internal_backtrace_1 ();
         ^~~~~~~~~~~~~~~~~~~~~~~~

Indeed, it looks like gdb_internal_backtrace_1 is never defined if
!GDB_PRINT_INTERNAL_BACKTRACE_USING_EXECINFO and
!GDB_PRINT_INTERNAL_BACKTRACE_USING_LIBBACKTRACE.

You can reproduce on Linux by deleting HAVE_LIBBACKTRACE and
HAVE_EXECINFO_BACKTRACE from your generated config.h.

Simon