So, a little bit of history:

I was trying to build my project for iOS. It did worked when I was using x86_64. But that actually happened because when one uses the libraries for lib-ios-x86_64 is already inferred as a simulator since actual x86_64 iOS phones does not exists.

The same doesn't happen for the arm64 host. When one tries to build to lib-ios-arm64, they're building for the real device.

For actually building to the iOS simulator, one needs the triple arm64-apple-ios12.0-simulator. Unfortunately, the simulator triple is more important than I wanted, since without it, it causes the following linking error:

ld: building for 'iOS-simulator', but linking in object file (/Users/rdgsnm/Documents/HipremeEngine/build/appleos/D/static/libdruntime-ldc.a[4](bitop.o)) built for 'iOS'