Test environments

Local:
- OS X 12.6: R 4.2.1
Appveyor:
- Windows Server 2012: R-release, R-devel, R-oldrel
Travis-CI:
- Ubuntu 16.04: R-release, R-devel
- OS X, with and without homebrew: R-release, R-devel
Rhub:
- Windows Server 2008 R2 SP1, R-devel, 32/64 bit
- Ubuntu Linux 16.04 LTS, R-release, GCC
- Fedora Linux, R-devel, clang, gfortran
- Debian Linux, R-devel, GCC ASAN/UBSAN

R CMD check results

There were no ERRORs, WARNINGs or NOTEs.