[Bug c++/77772] Segmentation fault when running an application with gdb

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77772

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
This looks like a libc/loader issue to me.  My source points at

/* Initialize _r_debug if it has not already been done.  The argument is
   the run-time load address of the dynamic linker, to be put in
   _r_debug.r_ldbase.  Returns the address of _r_debug.  */

struct r_debug *
internal_function
_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns)
{
  struct r_debug *r;

  if (ns == LM_ID_BASE)
    r = &_r_debug;
  else
    r = &GL(dl_ns)[ns]._ns_debug;

  if (r->r_map == NULL || ldbase != 0)

and thus 'r' being NULL.