> Where unsigned does benefit here is when these are used as indices into an array. The signed behavior will almost certainly produce invalid indices which leads to memory unsafety issues. The unsigned way will never do that, it’ll stay bounded, even if the index it produces is actually wrong. This is a much less-severe logic bug, but can still be used maliciously depending on context.

The argument for signed often goes that it's easier to detect an invalid operation on an index by checking for bounds, or the higher probability of segmentation faults, than if your index is always “valid”. Granted, even with signed your invalid operation might still give a valid index. Simply put, seeing a negative index in your debugger is an obvious red flag you lose with unsigned.

In general I want to complain about the idea that a subtle bug is less severe than an obvious bug. Obvious bugs can be caught automatically or manually and are therefore less severe than subtle ones. This is a mistakes all students do btw. Segmentation faults are your friends!