Classes from V2 "modules" are accessible on the compile classpath (but inaccessible at runtime by default)

[gharrma]

What happened?

Plugins can easily be hit by ClassNotFoundException at runtime if they access classes from V2 "modules".

I've created a minimal repro scenario as a patch on top of the intellij-platform-plugin-template: gharrma/intellij-plugin-repro-module-dependency-violation@8291e98

Observed behavior:

• ./gradlew assemble succeeds

• ./gradlew verifyPlugin reports no issue (version: 1.373)

• At runtime, a ClassNotFoundException is thrown when accessing class
  com.intellij.smartUpdate.VcsUpdateStep.

Expected behavior:

• Compilation should fail because module intellij.smart.update should not
  be on the compile classpath.

• The intellij-plugin-verifier should complain that classes from
  module intellij.smart.update are being used without a corresponding
  dependency declaration in plugin.xml, specifically:

  <dependencies>
    <module name="intellij.smart.update"/>
  </dependencies>
  

---

Note, I believe commit JetBrains/intellij-community@6fb57f5 in IntelliJ 2024.2 is what placed V2 modules into a separate classloader at runtime (thus requiring the explicit dependency declaration in plugin.xml).

Let me know if I should file a separate issue for intellij-plugin-verifier, given that the verifier should be reporting these dependency violations too. (Should I file this issue on YouTrack?)

Relevant log output or stack trace

java.lang.NoClassDefFoundError: com/intellij/smartUpdate/VcsUpdateStep
	at org.jetbrains.plugins.template.listeners.MyApplicationActivationListener.applicationActivated(MyApplicationActivationListener.kt:14)
	...
Caused by: java.lang.ClassNotFoundException: com.intellij.smartUpdate.VcsUpdateStep PluginClassLoader(plugin=PluginDescriptor(name=IntelliJ Platform Plugin Template, id=org.jetbrains.plugins.template, descriptorPath=plugin.xml, path=~/dev/misc/repro-module-dependency-violation/build/idea-sandbox/IC-2024.2/plugins/IntelliJ Platform Plugin Template, version=2.0.1, package=null, isBundled=false), packagePrefix=null, state=active, parents=, )
	at com.intellij.ide.plugins.cl.PluginClassLoader.loadClass(PluginClassLoader.kt:157)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
	...

Steps to reproduce

[See repro steps in the main description.]

Gradle IntelliJ Plugin version

2.0.1

Gradle version

8.9

Operating System

macOS

Link to build, i.e. failing GitHub Action job

No response

[gharrma]

It appears this might be related to the to-do comment added in commit abc9ee7.

[hsz]

Fixed by removing!