Found the following significant warnings:
  Rsrv.h:433:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.h:49:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.h:59:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.h:60:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.h:69:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.c:49:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  RSserver.c:171:17: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rsrv.h:427:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.h:6:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.h:8:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.h:10:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.h:11:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.h:12:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.h:13:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.h:14:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.h:15:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  tls.h:16:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:381:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:505:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:508:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:510:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:989:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:1038:12: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:1083:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:1095:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:1890:8: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:1947:16: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2234:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2560:9: warning: ‘d2i_RSAPrivateKey’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2572:5: warning: ‘RSA_new’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2580:13: warning: ‘RSA_free’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2585:17: warning: ‘RSA_generate_key_ex’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2587:25: warning: ‘RSA_free’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2619:9: warning: ‘i2d_RSAPublicKey’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2627:9: warning: ‘RSA_size’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2630:17: warning: ‘RSA_private_decrypt’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
  Rserv.c:2689:7: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2693:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2712:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2753:16: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2886:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2896:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2901:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:2923:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:3165:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:4910:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:4918:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  Rserv.c:4991:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ioc.c:135:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ioc.c:136:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ioc.c:137:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ioc.c:144:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.c:67:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.c:83:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.c:132:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  md5.c:192:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  session.h:18:8: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  session.c:68:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  session.c:69:18: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  tls.c:29:8: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.c:79:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.c:83:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.c:155:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ulog.c:182:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  utils.c:81:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.h:79:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.h:89:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.h:90:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.h:99:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  tls.h:12:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  chandler.h:21:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.c:51:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.c:205:17: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.c:329:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.c:337:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  server.c:366:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  chandler.c:31:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
See ‘/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/Rserve.Rcheck/00install.out’ for details.