Warning: The macOS 12 SDK does not appear to be installed. Ports may not build correctly.

[Daniel J. Luke]

On Oct 30, 2021, at 5:25 PM, Nils Breunese <nils at breun.nl> wrote:
> But I indeed don’t seem to have an SDK for macOS 12:
> 
> So far I haven’t had any ports not building correctly. Is this a known issue? Does it have a known solution?

Yes - you can fix it by re-installing the command line tools:

https://trac.macports.org/wiki/ProblemHotlist#reinstall-clt

(this happened to me on upgrade to macOS 12 as well).

-- 
Daniel J. Luke