ubuntu16.04.6， gcc 5.4.0 编译报错

[ghost]

make -C string; make -C alloc; make -C basefunc; make -C json; make -C crypto; make -C struct_mod; make -C memdb; make -C message; make -C dispatch; make -C ex_module; make -C connector; make -C channel; make -C sys_func;
make[1]: Entering directory '/home/shareData/Yu/cube-1.3/cubelib/string'
gcc -g -c -fPIC -Wall -DUSER_MODE memfunc.c
memfunc.c: In function ‘Memcpy’:
memfunc.c:31:20: warning: pointer targets in initialization differ in signedness [-Wpointer-sign]
unsigned char * d=(char *)dest;
^
memfunc.c:32:20: warning: pointer targets in initialization differ in signedness [-Wpointer-sign]
unsigned char * s=(char *)src;
^
我截了部分错误。错误原因是我的gcc版本问题么？