In this example:

struct fooo {} ;
struct fooo x;

void test(void) {

  *({
    0;
    x/x;
    });
}

We emit two diagnostics: one about x/x (good) and one about "indirection requires a pointer operand".  The problem is that we correctly kill the expression tree for x/x, but that means that we build and return a  compound statement with just { 0; } and the stmt expr gets built with type int.  We should somehow propagate invalidity of the last statement in a stmt expr up into the stmt expr itself.

This came from PR4065.