Some days ago, the CRAN check with R-devel started to raise "Found non-API calls to R" NOTE. I'm not sure if they are serious on disallowing these not-so-minor APIs, but what should I do? Do you take some action or just wait? #stats
For example, rlang package now has these NOTE:
File ‘rlang/libs/rlang.so’:
Found non-API calls to R: ‘R_ClosureExpr’, ‘R_PromiseExpr’,
‘SETLENGTH’, ‘SET_ENCLOS’, ‘SET_ENVFLAGS’, ‘SET_TRUELENGTH’
