You are not being "Old Fashioned"! Just stick to using the Standard C Library and your code will be very portable. Avoid most, if not all of the compiler specific extension functions!
C is for anyone who will take the time to thoroughly learn the language, understand it's pitfalls, and how to avoid them! You don't have to become an "expert" to use and appreciate the language!
If you read my previous reply, you know that cppcheck is available for MacOS. Look at the Cppcheck web page, and you will see that the command presented, "brew install cppcheck" should install it on you Mac.
I don't use Mac so you are on your own if the command you need is different than the one presented.
As for other possible Static Code Analyzers for MacOS, a simple Google search command will present many sites you can explore for other analyzers. I can't do all the work for you!
Good luck!