[pdt@c-68-53-40-50 mod_voicemail]$ cat test.c
#include <stdio.h>
#include <stdlib.h>

typedef struct test_struct test_struct;

struct test_struct {
        int var1;
        int var2;
};

static void increment(test_struct* test) {
        test.var1++;
}

int main(char** argv, int argc) {
        test_struct *tsst;

        test = malloc(sizeof(*test));

        test.var1 = 1;
        test.var2 = 2;

        increment(test);

        fprintf(stdout, "test.var1: %d", test.var1);
}
[pdt@c-68-53-40-50 mod_voicemail]$ gcc test.c -o test
test.c: In function ‘increment’:
test.c:12: error: request for member ‘var1’ in something not a structure or union
test.c: In function ‘main’:
test.c:18: error: ‘test’ undeclared (first use in this function)
test.c:18: error: (Each undeclared identifier is reported only once
test.c:18: error: for each function it appears in.)