Judging by the motivation section, the motivation is primarily for FPGAs which I guess is why they want to allow these sub-int sized bit values. You might come

Judging by the motivation section, the motivation is primarily for FPGAs which I guess is why they want to allow these sub-int sized bit values. You might come up with some custom C-programmable operator that is only 3-bits wide where before you're presumably forced to use the smallest available power of 2 word size which would waste resources. So I think actually the idea is that this is for code which is not supposed to be portable at all, but rather hyper-optimised for custom devices.