`forgetting` is not an edge case. In the context of rust, having an API that invokes unsafe behavior without it being marked unsafe is not acceptable. Keeping ourselves to this rule is what makes the concept of `unsafe` useful because we can rely on the behavior/api-spec of other code.
Failing to ensure correct behavior in the presence of `forget` means that once the program gets complex enough it can blow up in undetermined ways because one piece of code somewhere wasn't aware of a restriction in another piece of code that is potentially very far away.
Failing to isolate this type of unsafety is a pitfall waiting for some future developer to be trapped in.
I've never personally seen or used mem::forget. I'm sure it happens, of course, and I'm in agreement that the API should be unsafe. I'm just saying it's not clear that they "don't care".
Failing to ensure correct behavior in the presence of `forget` means that once the program gets complex enough it can blow up in undetermined ways because one piece of code somewhere wasn't aware of a restriction in another piece of code that is potentially very far away.
Failing to isolate this type of unsafety is a pitfall waiting for some future developer to be trapped in.