Found the following significant warnings:
  ./epanet2.h:91:25: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:99:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:101:25: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:103:25: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:111:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:123:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:125:25: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:135:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:145:26: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:149:31: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./epanet2.h:151:31: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:30:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:37:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:132:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:145:23: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:147:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:149:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:157:23: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:175:23: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:177:22: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:187:23: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:197:23: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:204:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  epanet2.c:206:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./filemanager.h:42:35: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  filemanager.c:40:35: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  hash.c:52:28: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:23:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:39:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:41:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:43:18: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:48:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:50:12: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:51:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./toolkit.h:52:14: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./mempool.h:19:32: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  mempool.c:42:39: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  mempool.c:68:32: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:354:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:937:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:969:19: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:988:18: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:1028:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:1059:12: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:1075:13: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  toolkit.c:1091:14: 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/epanet2toolkit.Rcheck/00install.out’ for details.
* used C compiler: ‘Debian clang version 15.0.6’