He instalado gdb 8.1 con brew.

También tengo codeign gdb y .gdbinit como se muestra a continuación:

set startup-with-shell off.

He desactivado la función SIP:

$ csrutil status
System Integrity Protection status: disabled.

Pero gdb todavía no funciona:

#include <iostream>
using namespace std;

int main() {
  cout << "hello world!" << endl;
  return 0;
}

Compilar comando:

g++ -g test.cpp

salida de gdb:

GNU gdb (GDB) 8.1
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin17.3.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...Reading symbols from /Users/mypc/Downloads/a.out.dSYM/Contents/Resources/DWARF/a.out...done.
done.
(gdb) run
Starting program: /Users/mypc/Downloads/a.out 
[New Thread 0x2503 of process 802]
[New Thread 0x2303 of process 802]
During startup program terminated with signal ?, Unknown signal.
(gdb) 

¿Qué pasos correctos para hacer que gdb funcione en macos sierra?