Found the following significant warnings:
  arffunctionlibrary.c:290:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:319:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:308:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:337:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:280:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:420:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:433:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:415:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:462:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:457:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:388:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:391:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:529:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:559:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:545:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:581:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:516:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:671:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:686:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:666:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:715:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:710:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:635:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:639:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:824:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:805:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:846:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:768:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:772:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:903:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:923:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:918:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  arffunctionlibrary.c:894:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
See '/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/arf3DS4.Rcheck/00install.out' for details.