[steveklabnik]

I do absolutely understand that UB does not prohibit implementations from defining something. That’s part of the core of what we’re taking about! I’m saying rustc chooses to never do so. C and C++ compilers do choose to do so. That distinction is what we’re talking about.

(As well as that overflow is UB in one language and not another, of course.)

[mehrdadn]

No comment on everything else I wrote beyond that 1 sentence? Your positions are quite contradictory, which is what I've been trying to explain in the entire comment.

[steveklabnik]

I just don't think we're going to get anywhere, but wanted to correct the assertion that I do not understand this aspect of UB.

[mehrdadn]

I mean, your positions are contradictory, but sure.