alt Hacker NewsI understand the difference and this is why I said "similar constraints". Once you have non-value (trap) representations you need to be careful when dereferencing pointers cast to different types, even if you do not have strict aliasing. The point under the discussion upthread was that in unsafe Rust this would not be a problem because it does not have strict aliasing and my argument that it still is would be because of non-value representations.
It's true that care still needs to be taken. Many people in C are critical of strict aliasing (Linus as a major example) while not being too worried about the dangers when punning. Strict aliasing adds additional things you need to worry about on top of the representation issues. It's a worry you have in C (unless you use a flag and write non-standards conforming code) that you don't have in Rust.