Found the following significant warnings:
  heatapprox.c:13:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linScrossdist.c:31:15: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  linScrossdist.c:80:14: warning: passing arguments to 'Clinvdist' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linScrossdist.c:34:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linSnncross.c:26:15: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  linSnncross.c:26:33: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./linSnncross.h:66:12: warning: passing arguments to 'Clinvdist' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linSnncross.h:22:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linSnncross.h:63:17: warning: passing arguments to 'Clinvwhichdist' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linSpairdist.c:36:15: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./linSpairdist.h:79:14: warning: passing arguments to 'Clinvdist' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linSpairdist.h:28:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  lincrossdist.c:24:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  lineardisc.c:141:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linearradius.c:24:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linequad.h:21:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linequad.h:270:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linknnd.h:71:18: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./linknnd.h:71:35: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  ./linknnd.h:99:14: warning: passing arguments to 'linvknndist' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linknnd.h:132:7: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linknnd.h:139:7: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linknnd.h:150:2: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linknnd.h:39:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linnncross.h:19:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linnndist.c:23:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linnndist.c:102:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linpairdist.c:24:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  lintileindex.c:21:1: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  ./linvdist.h:26:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:61:20: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  linvknndist.c:93:5: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:96:5: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:141:12: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:149:12: warning: passing arguments to 'UpdateKnnList' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:36:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  linvknndist.c:172:5: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
  lixel.c:14:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
See ‘/data/gannet/ripley/R/packages/tests-clang/spatstat.linnet.Rcheck/00install.out’ for details.