[jira] Commented: (MNG-4761) Plugin-level dependency scope causes some plugin classpaths to be incorrect

["Benjamin Bentmann (JIRA)" <ji...@codehaus.org>]

    [ http://jira.codehaus.org/browse/MNG-4761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=231708#action_231708 ] 

Benjamin Bentmann commented on MNG-4761:
----------------------------------------

For future reference, the failing test scenario centeres around the following dirty tree for the plugin depencencies:
{noformat}
plugin
+- override:0.1:compile
|  \- middle:0.1:compile        <-----------\
|     \- required:0.1:compile    <---\      |
+- direct:0.1:runtime                (a)    |
|  +- required:0.1:runtime       <---/      |
|  \- middle:0.1:runtime        <--------- (b)
|     \- required:0.1:runtime               |
\- middle:0.2:runtime           <-----------/
{noformat}
During resolution of conflict (a), the node {{required:0.1:runtime}} will be disabled in favor of {{required:0.1:compile}}, although the runtime-scope dependency is nearer, i.e. Maven's usual conflict resolution strategy of nearest-wins is violated here. When conflict (b) is resolved, all {{middle:0.1:*}} nodes including their children will be disabled, thereby completely losing {{required:0.1}} on the plugin class path.

So while using runtime scope for the project-level plugin dependencies workarounds the problem, the issue remains for ordinary project dependency resolution. I wonder if it got filled already.

> Plugin-level dependency scope causes some plugin classpaths to be incorrect
> ---------------------------------------------------------------------------
>
>                 Key: MNG-4761
>                 URL: http://jira.codehaus.org/browse/MNG-4761
>             Project: Maven 2 & 3
>          Issue Type: Bug
>          Components: Artifacts and Repositories, Plugins and Lifecycle
>    Affects Versions: 2.2.1, 3.0-beta-1, 3.0-beta-2
>            Reporter: John Casey
>            Assignee: John Casey
>             Fix For: 2.2.2, 3.0-beta-3
>
>         Attachments: MNG-4761-mvn3b2.patch, MNG-4761-mvn3b2.reformatted.patch, obscured-nearer-dep.zip
>
>
> Plugin-level dependencies should use RUNTIME scope at all times. Using any other scope may alter the weighting given to the subgraph-choice algorithm used in transitive dependency resolution.
> Plugin-level dependencies use compile scope by default. When transitive resolution takes place, compile scope takes precedence over runtime scope, causing the transitive dependency sub-graph of the plugin-level dependency to be activated over those of the plugin itself.
> This happens even when the plugin's transitive dep is NEARER to the top level than the one brought in by that plugin-level dependency itself.
> The result is that when a dep that's farther away is chosen over a nearer one, it can then be disabled by Maven choosing to disable its parent dep (the one that brought it in) in another part of the transitive resolution process.
> This is a very subtle case where Maven is doing the wrong thing. The attached test case should make it clearer.

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