I have no idea how to solve incompatible pointer types passing warnings.

── R CMD check ─────────────────────────────────────────────────────────────────
─ using log directory ‘/private/var/folders/lr/g4jxbpys6z54qrs4ppyln72c0000gn/T/rcheck-sampling-20191218-222222/sampling.Rcheck’ (339ms)
─ using R version 3.5.2 (2018-12-20)
─ using platform: x86_64-apple-darwin15.6.0 (64-bit)
─ usin