It often happens that after a successful build I do some small changes that cause some compiler errors, but undoing those changes with Cmd-Z still leave the errors there. Building also doesn't remove them. Only cleaning the project and building again (which is very time consuming) or doing a small edit on the line that Xcode still thinks is wrong (such as adding a whitespace and immediately undoing it) finally gives a successful compilation again.
I filed a bug report in September 2018, more than 3 years ago, and never got a response. Can it really be that I'm the only one experiencing this and why does it take so long to fix such annoying bugs and why does nobody care to give some reassurance that somebody is working on this?