I am building my pacakge with rstantools, and everything is ok but, when I do a full check I got this warning:
> checking compilation flags used ... WARNING
Compilation used the following non-portable flag(s):
'-Wno-deprecated-declarations' '-Wno-ignored-attributes'
'-march=native'
including flag(s) suppressing warnings
I don’t know how to fix this warning, I am using R4.0.0 rstantools2.0.0 and rstan2.19.3
These notes sound like they would prevent you from putting your package on CRAN. If you are not planning to do that, then it’s possibly ok, but you may cause issues to the user session (I don’t know if that’s really the case, but I would play it safe).
Have you tried to reach those code paths and see what happens?
Are you using any custom fortran code in your package? My answer assumed you did, but if you don’t perhaps it’s some spurious note that you can’t possibly fix anyway.