LDC 1.20 is stable version. Added iOS / watchOS / tvOS supported! based on DMD 2.090.1 :)
Dependency LLVM version can be 8.0 ! FreeBSD 12.x used this version!
LDC 1.22.0 now
Patch for 1.22.0 is available in bug #237427 *** This bug has been marked as a duplicate of bug 237427 ***