Excellent, thank you JdeHaan.
Is that with selecting FPC 3.2.2 or .. ?
Please report this issue in the FPC bugtracker (see link at left side). Make sure to mention which FPC version you were trying to build together with the version of macos (and xcode) for which this was attempted and post the error-logs (especially the second part).
There is a mention of an rtti build error (error
41043) with delphi rtti enabled but it seems there is more to this issue.
I am not 100% sure if they are related though (the result of the report differs).