1. Building GDB for Darwin

Creating the binary for Darwin isn't very difficult. Download a release snapshot or get the current source via git/CVS/FTP, then configure and make as usual.

Building the 7.0 release unfortunately results in many "warning: format not a string literal and no format arguments" warnings. This problem has been fixed in CVS. To avoid such warnings building 7.0, configure with --disable-intl. Later releases are fine and do not require any special build options.

2. Giving gdb permission to control other processes

If you try to use your freshly built gdb, you will get an error message such as:

Starting program: /x/y/foo
Unable to find Mach task port for process-id 28885: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))

Please see the PermissionsDarwin page to fix that.

3. Disable starting the debuggee (inferior) via a shell

On macOS 10.12 (Sierra) and later, you must

Use gdb 7.12.1 or later
Additionally prevent gdb from using a shell to start the program to be debugged. You can use the following command for this inside gdb:

set startup-with-shell off

You can also put this last command in a file called .gdbinit in your home directory, in which case it will be applied automatically every time you start gdb.