Found the following significant warnings:
  ./cli.h:13:18: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:19:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:40:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:58:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:62:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:63:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:64:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:68:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:69:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cli.h:102:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cleancall.h:31:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./cleancall.h:42:27: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ansi.c:111:38: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  cleancall.c:38:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  cleancall.c:141:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:8:17: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:26:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress-altrep.c:54:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress-altrep.c:58:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress.c:69:29: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress.c:80:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress.c:87:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  progress.c:306:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  thread.c:80:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  thread.c:118:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  thread.c:139:21: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  tty.c:15:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  utils.c:44:18: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  win-utf8.c:12:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
See '/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/cli.Rcheck/00install.out' for details.