clang ub stuff

clang.c

#include <stdio.h>

#define BUGGY

void funcA(int s, int g)
{
    int i, j = 0, k;
    int grp[4] = {-1, -1};

    for (i = 0, k = 0; i < 1; ++i)  {
        for (j = 0; j < 1; ++j) {
            if ( grp[g] > 0 )
            {
                if ( g > 5 ) {
                    continue;
                }
                else  {
#ifdef BUGGY
                    *(long long *)grp = 0;
#else
                    *(int *)grp = 0;
                    *(((int *)grp) + 1) = 0;
#endif
                }
            }

            grp[k++] = 0;
        }

        printf("this should be zero: %d\n", grp[0]);
    }
}


int main(void) {
    funcA(0, 1);
}

void
funcA(int g)
{
	int grp[4];
	int k = 0;

	grp[0] = grp[1] = grp[2] = grp[3] = -1;

	printf( "  %s:%s:%d: grp[0]:%d\n", __FUNCTION__, __FILE__, __LINE__, grp[0]);

	for (int j = 0; j < 1; ++j ) {
		if ( grp[g] > 0 )
			*(long long *)grp = 0;

		if ( g < 100 )
			grp[k++] = 0;
	}

	printf( "  %s:%s:%d: grp[0]:%d\n", __FUNCTION__, __FILE__, __LINE__, grp[0]);

	return;
}

int
main( void)
{
	funcA(1);

	return (0);
}

seems to be more mimimal