Function TRUELENGTH 

unsafe fn TRUELENGTH(x: SEXP) -> R_xlen_t

Get the true length (allocated capacity) of a vector.

May be larger than LENGTH for vectors with reserved space. ALTREP-aware. Checked wrapper for TRUELENGTH. Calls TRUELENGTH_unchecked and routes through with_r_thread. Generated from source location line 2271, column 8. Generated from source file miniextendr-api/src/ffi.rs.