extern void allo(char *);

void foo(void)
{

        char achar[10];
        unsigned char auchar[10];

        allo ( achar );
        allo ( auchar );

}

qcc -V4.2.1,gcc_ntox86 -w9 -funsigned-char try.c
will give: "pointer targets in passing argument 1 of 'allo' differ in signedness" even though -funsigned-char is 
specified!

- Mario