Make std::cmp::Ord documentation specify what it means to agree with PartialEq

This commit is contained in:
Czipperz 2018-12-29 17:48:43 -05:00
parent 43d26b1f35
commit cf3959c5b0

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@ -472,9 +472,10 @@ impl<T: Ord> Ord for Reverse<T> {
/// Then you must define an implementation for `cmp()`. You may find it useful to use
/// `cmp()` on your type's fields.
///
/// Implementations of `PartialEq`, `PartialOrd`, and `Ord` *must* agree with each other. It's
/// easy to accidentally make them disagree by deriving some of the traits and manually
/// implementing others.
/// Implementations of `PartialEq`, `PartialOrd`, and `Ord` *must*
/// agree with each other. That is, `a.cmp(b) == Ordering::Equal` if
/// and only if `a == b`. It's easy to accidentally make them disagree
/// by deriving some of the traits and manually implementing others.
///
/// Here's an example where you want to sort people by height only, disregarding `id`
/// and `name`: