You'll need to give the exact versions of macOS and Xcode, and any special options you're trying to use. It's definitely built successfully on macOS since we updated to the latest bx and bgfx.
I have a dev build of MacOS (either a late 10.14.2 or 10.14.3 beta 1, as 10.14.3 Beta 2 is available to download now) with the latest non-beta Xcode (10.1).
And I don't think that I'm compiling with any unusual parameters. -j5 and PTR64=1 are all that I'm using.
If there is anything else that I have to provide, let me know. Thanks.