Package check result: NOTE

Check: CRAN incoming feasibility, Result: Note_to_CRAN_maintainers
  Maintainer: ‘Sebastian Krantz <sebastian.krantz@graduateinstitute.ch>’

Check: compiled code, Result: NOTE
  File ‘collapse/libs/collapse.so’:
    Found non-API calls to R: ‘SETLENGTH’, ‘SET_TRUELENGTH’, ‘TRUELENGTH’
  
  Compiled code should not call non-API entry points in R.
  
  See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual,
  and section ‘Moving into C API compliance’ for issues with the use of
  non-API entry points.

No changes to worse in reverse depends.