Cannot use pointer arithmetic on struct field

[kamphaus]

typedef unsigned char pcre_uchar;
typedef struct spu {
    pcre_uchar *hvm;
} spu;
// ...
pcre_uchar str[] = "abcd";
spu s;
spu *ps = &s;
ps->hvm = &str[1];
is_true(ps->hvm == &str[1]);
ps->hvm += 2;
is_true(ps->hvm == &str[3]);

is valid C code, but go build has error ps.hvm undefined (type []spu has no field or method hvm)