Found the following significant warnings:
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/libgeos/include/libgeos.h:46:34: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/libgeos/include/libgeos.h:434:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/wk/include/wk-v1.h:101:32: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/wk/include/wk-v1.h:106:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:179:35: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:181:24: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:182:35: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:183:33: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:380:17: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:394:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:401:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/libgeos/include/libgeos.c:8:27: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/libgeos/include/libgeos.c:262:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/libgeos/include/libgeos.c:263:33: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/wk/include/wk-v1-impl.c:50:32: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/wk/include/wk-v1-impl.c:148:28: 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/geos.Rcheck/00install.out' for details.