Found the following significant warnings:
  redland.c:1564:29: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:1600:36: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2211:46: warning: passing 'char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2457:64: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2536:73: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2589:75: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2638:61: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2693:67: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:2757:70: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:3810:74: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:3869:73: warning: passing 'char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5492:71: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5545:60: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5599:79: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5661:68: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5796:70: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5796:89: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
  redland.c:5943:74: warning: passing 'const char *' to parameter of type 'const unsigned char *' converts between pointers to integer types where one is of the unique plain 'char' type and the other is not [-Wpointer-sign]
See '/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/redland.Rcheck/00install.out' for details.