All operands are always promoted to int (or unsigned int, long, unsigned long, etc.) before any operation. The footgun in this example is that even though you'r

All operands are always promoted to int (or unsigned int, long, unsigned long, etc.) before any operation. The footgun in this example is that even though you're using unsigned integers and would expect guaranteed wrapping semantics, the promotion to signed int makes it UB for USHORT_MAX*USHORT_MAX.