Docs for fetch_add/fetch_sub/pow and overflow behavior

fetch_add fetch_sub pow

Do docs for those methods need to explain what happens on overflow? There are three possible overflow behaviors: panic, saturate, wrap. Is it obvious what those methods do on overflow?

Perhaps we should explain? I guess fetch_add and fetch_sub wrap around, while pow panics in debug mode and wraps around in release mode.

cc @alexcrichton

[steveklabnik]

The default behavior for overflow is "panic in debug mode, wrap in release mode." So anything that does that does not need a note. Anything else should get one.

In that case, we must add a note for fetch_add and fetch_sub. They don't panic in debug mode: https://is.gd/AnruSb

[ollie27]

Dupe of #34618?

[alexcrichton]

Yeah just adding a note here about overflow should be fine, but yeah looks like a dupe of #34618 so closing