NoClassDefFoundError on a protocol when requiring its namespace

This is the recipe for the exception I'm getting (EDIT: ProtoImpl is defined in an开发者_JS百科other ns, I'll leave it out to ease the description):

myns.clj

(ns myns)

(defprotocol Proto
  (func [this]))

(extend-protocol Proto
  ProtoImpl
  (func [this] (do-something ...)))

interop.clj

(ns interop
  (:require [myns :as m]))

(defn startup
  []
  (m/func (ProtoImpl.)))

(gen-class :name interop.Interop
           :prefix "interop-"
           :methods [[boot [] void]])

(defn interop-boot
  [this]
  (startup)))

Both myns.clj and interop.clj are shipped within a webapp, the latter being also AOT compiled thus produging Interop.class available in the classpath right away. This is instantiated as a Spring bean.

When the webapp starts, it fails to bootstrap with the following exception:

[...]
    at myns__init.load(Unknown Source)
    at myns__init.<clinit>(Unknown Source)
[...]
    at interop.Interop.<clinit>(Unknown Source)
[...]
Caused by: NoClassDefFoundError: myns.Proto

What can cause this issue?

EDIT: I cannot reproduce the error anymore, I recompiled and re-run the application, which started up flawlessly... Still I would really like to understand in which situations such an issue can show up.

It looks to me like the class loader couldn't find the class definition for Proto, which I assume is the role of clojure RT to load as soon as the relevant .clj source file is parsed. As you can see in the extract of the stack trace I receive, myns is being loaded, and it it exactly there that Proto is defined. How come I got a NoClassDefFoundError?

Clojure Records are supposed to be imported. The following should work:

(ns interop
  (:require [myns :as m])
  (:import  myns.Proto))

I was having the same problem. Adding both classes to :aot in my project.clj resolved the issue. Your project.clj would have something like this: :aot [myns interop].