Check results using R-devel on an arm64 ('M1') Mac with Xcode/CLT 13
and an experimental build of gfortran (a fork of 11.0).

Details as in the R-admin manual of R-devel.

External libraries 

   mariadb-connector-c proj.pc SYMPHONY

were patched.

hdf4, hdf5 needed -Wno-implicit-function-declaration in their CFLAGS.
pcre2 (and pcre for RcppCWB) were built with --disable-jit .

Currently this uses PROJ 8.1.1, GEOS 3.9.1, GDAL 3.3.1 and gsl 2.7.
pandoc is the Intel Mac version, currently 2.14.2 (and updated often).
(There is a self-contained M1 build available from Homebrew.)
Java is 17 from https://adoptium.net

I built JAGS from its sources: the script and a tarball are at
https://www.stats.ox.ac.uk/pub/bdr/JAGS-arm64/

There is a testing service for the CRAN M1mac setup at
https://mac.r-project.org/macbuilder/submit.html

Some ways in which this differs from the CRAN checks:

- Using R-devel not R-release
- timezone is Europe/London not Pacific/Auckland
- OS and Command Line Tools are kept up-to-date
- Clp and SYMPHONY are installed
- Current pandoc is installed
- External software is (mainly) kept up to date -- see above.