Hello david_hello, sorry, haven't seen Keil Studio Cloud issuing errors related to "clang" like that and also not the not reporting errors in source code like you have. So I still think, this is something project related. And we might be able to comment something, if you could share a project with that we can reproduce the error(s)
how to share project?
If possible to put it in a public GitHub repo, we could just import it from there. Else, you can also open a support case on developer.arm.com and attach the project to your case.