<code>comparable</code> may only be used as type constraints. They cannot be the types of
values or variables, or components of other, non-interface types.
</p>

<h4 id="Satisfying_a_type_constraint">Satisfying a type constraint</h4>

<p>
A type argument <code>T</code><i> satisfies</i> a type constraint <code>C</code>

pkg go/build/constraint, type AndExpr struct, Y Expr
pkg go/build/constraint, type Expr interface, Eval(func(string) bool) bool
pkg go/build/constraint, type Expr interface, String() string
pkg go/build/constraint, type Expr interface, unexported methods
pkg go/build/constraint, type NotExpr struct
pkg go/build/constraint, type NotExpr struct, X Expr
pkg go/build/constraint, type OrExpr struct

  // WhenUnsatisfiable indicates how to deal with a pod if it doesn't satisfy
  // the spread constraint.
  // - DoNotSchedule (default) tells the scheduler not to schedule it.
  // - ScheduleAnyway tells the scheduler to schedule the pod in any location,
  //   but giving higher precedence to topologies that would help reduce the
  //   skew.
  // A constraint is considered "Unsatisfiable" for an incoming pod

- Added `optionalOldSelf` to `x-kubernetes-validations` to support ratcheting CRD schema constraints. ([#121034](https://github.com/kubernetes/kubernetes/pull/121034), [@alexzielenski](https://github.com/alexzielenski))

- Pod spread constraints have been added in alpha. You can use these constraints to control how Pods are spread across the cluster among failure-domains. ([#77327](https://github.com/kubernetes/kubernetes/pull/77327), [#77760](https://github.com/kubernetes/kubernetes/pull/77760), [#77828](https:/...

- Graduated support for `minDomains` in pod topology spread constraints, to general availability.
  The `MinDomainsInPodTopologySpread` feature gate no longer has any effect, and the field is

  Previously, when unschedulable Pods are updated, the scheduler always put Pods back to activeQ/backoffQ. But, actually not all updates to Pods make Pods schedulable, especially considering many scheduling constraints nowadays are immutable.

- Revised the logic for DaemonSet rolling update to exclude nodes if scheduling constraints are not met.

- New parameter `defaultingType` for `PodTopologySpread` plugin allows to use k8s defined or user provided default constraints ([#95048](https://github.com/kubernetes/kubernetes/pull/95048), [@alculquicondor](https://github.com/alculquicondor)) [SIG Scheduling]

  matching the spreading selector on those excluded nodes (not matching the node affinity/selector),
  especially when the `topologyKey` is not node-level. Revisit the node affinity and/or pod selector in the
  topology spread constraints to avoid this scenario. ([#107009](https://github.com/kubernetes/kubernetes/pull/107009), [@kerthcet](https://github.com/kerthcet))