Finding unsoundness bugs isn't the most unusual, yes. But this one is unusual in how simple the code that causes it can be (see the versions of the reproducer code in the comments). For other unsoundness bugs, the code would need to contort itself a lot to avoid the compiler checks.

Yeah, if my read of maxdexh's comment¹ is right, this is a remarkably straightforward gap. Definitely surprising it survived this long.

1: https://github.com/rust-lang/rust/issues/164250#issuecomment...