void f()
{
    (a, b, c, d);   // comma expression inside parenthesized expression
    a, b, c, d; // straight comma expr
    if (stuff(), a);
    for (int a = 4, b = 5;
         call(), a < 7;
         ++a, ++b) {}
    half a, b = 3 + (4,6), c;
}