> The standard counterexamples being XOR linked lists, or manual paging with mmap, or manipulating addresses as integers within asm!(), or literally any situati

> The standard counterexamples being XOR linked lists, or manual paging with mmap, or manipulating addresses as integers within asm!(), or literally any situation where you can't afford to keep the address as a single value-with-provenance sitting at a known location in program memory until you need it. Well there's a crucial distinction in play here. The XOR linked lists, and some related tricks can be done with address exposure, we expose the pointer and get the integer address, then later when we reconstruct that integer we're allowed to turn it back into a pointer. Rust of course has (as part of the same experiment) APIs for that, you're just paying in terms of worse performance and no tooling (the tooling is disabled if you want these APIs). But the other cases are just voodoo magic, we don't have a model to explain why they should work, which also makes it very hard to, for example, debug them if they don't. They're platform specific. As with the inline assembler, Rust takes no responsibility for whether you can write a correct program in these circumstances, good luck. I don't agree that there isn't a practical difference between IFNDR and UB, I see attempts to confuse these as part of a desire to pretend that C++ isn't markedly worse at correctness than competitors, without the hard work to actually stop it from being markedly worse.