Found the following significant warnings:
  randomForestSRC.h:448:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:449:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:727:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:752:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1200:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1843:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1844:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1856:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1863:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1876:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1877:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1878:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1879:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1880:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1881:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:1950:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:2166:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:2168:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.h:2184:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:1490:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:1587:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:5846:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:6100:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  splitCustom.h:22:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:11955:16: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22095:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22401:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22810:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22845:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22859:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22896:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22904:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22927:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:22936:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:23817:11: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:27269:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:27282:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  randomForestSRC.c:27466:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ../inst/include/lapacke.h:161:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  ../inst/include/lapacke/lapacke_nancheck.h:38:12: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  splitCustom.c:8:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
See ‘/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/RFCCA.Rcheck/00install.out’ for details.
* used C compiler: ‘gcc-12 (Debian 12.2.0-13) 12.2.0’