AC6 + ST-Link V2 + SWD programming
It's simple)) But I lost a lot of time to find out.
You need to configure in the cube "Pinout -> SYS -> Debug -> Serial Wire".
Then create the project in Cube for SWD and compile it.
Program the controller once in a different way, for example with ST-LINK Utility.
Configure the project debugging as the author writes above: http://www.exclude.se/?p=170
Now debugging in SWD+STLink-V2 works withouth hardware reset line.
If you remove Debug -> Serial again, the debugging will not work again...