Found non-API calls to R: `SETLENGTH`, `SET_TRUELENGTH`

[jwood000]

Recently, my package RcppAlgos started getting NOTEs on several builds from CRAN checks:

https://cran.r-project.org/web/checks/check_results_RcppAlgos.html

The NOTE is: "Found non-API calls to R: SETLENGTH, SET_TRUELENGTH"

I did many grep checks in my code repository and could not find and occurrence of SETLENGTH or SET_TRUELENGTH. I then googled the NOTE and several packages popped up. All of them that I checked depend on cpp11.

I then found this issue for arrow, apache/arrow#41404, which talks about this problem as well.

Both of these calls appear occurring in the r_vector header:

cpp11/inst/include/cpp11/r_vector.hpp

Lines 898 to 903 in 51f4cd5

	inline SEXP truncate(SEXP x, R_xlen_t length, R_xlen_t capacity) {
	#if R_VERSION >= R_Version(3, 4, 0)
	SETLENGTH(x, length);
	SET_TRUELENGTH(x, capacity);
	SET_GROWABLE_BIT(x);
	#else

I also found this from r-source/wch in src/library/tools/R/sotools.R (check out lines 561 to 669):

https://github.com/wch/r-source/blob/becbbf2a71ed56d4f7503d2dc4ac391d8c05eac6/src/library/tools/R/sotools.R#L561-L669

I'm not really sure what action to take here, I just wanted to bring this to your attention.

Regards,
Joseph

[chainsawriot]

Can the first SETLENGTH be replaced by

x = Rf_xlengthgets(x, length); 

?

[chainsawriot]

Or this

r-lib/brio@19cedea#diff-4b539828f8475a0f5ae0e041e4bbfae0ce140219c19fdfd79da7cc1863170dac