I solved the problem by running DebugServer within one instance of Lazarus, and the starting a second instance of Lazarus which you can easily do by entering open -n /Applications/Lazarus.app. Strangely, even though the DbugIntf code definitely tries to invoke DbugSvr, debug info appears to be getting through to debugserver, for reasons that I don't understand, and frankly am to tired to investigate now!
It's strange what you say about dbugintf. The code around circa line 200 is this, on my machine:
No, I couldn't have tweaked the code, because, of course dbugintf.pp is part of a freshly installed Apple Mac version of FPC, and I notice that the date of the file is 7 Mar 2009. What vintage of dbugintf.pp do you have?
I've seen fleeting mentions of lldb but know nothing of it. Tell me more, or point me to somewhere I can read up about it.
I used the info translated from this page https://alexconesa.wordpress.com/2016/11/16/lldb-and-gdb-debug-in-lazarus/ in order to install lldb. My question though is what is the typical workflow for using lldb given that Lazarus doesn't support it directly yet (unless I'm mistaken about that)?