Not true, C++ made it so trivial infinite loops are not UB because it turns out they do have legitimate uses.

https://lists.isocpp.org/std-proposals/2020/05/1322.php

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2024/p28...

Yes, the C++ committee has been making some stupid decisions lately. This is not the only one.

Low level platform-specific code that needs to hot spin until an interrupt happens can use assembly for that part which it will need to do for the interrupt handler anyway.