Cached plugins are used, even when the specifically declared
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Key: MNG-3284
URL: http://jira.codehaus.org/browse/MNG-3284
Project: Maven 2
Issue Type: Bug
Components: Dependencies, Plugins and Lifecycle
Affects Versions: 2.0.7
Reporter: Nigel Magnay
Priority: Critical
Attachments: pluginbug.tar
In the attached project, you can build module A, then build module B, but the
top level aggregator project will fail at B.
The reason this happens is that maven seems to cache plugins. When B is built
in isolation, all things are fine - but when built in aggregation, one of the
plugins that it uses has already been instantiated, and so it uses that one.
This is incorrect, since the declared version is different in B, and is relying
on functionality not present in the version declared in A.
I have seen similar behaviour when a plugin relies on other plugins to get work
done - all of a sudden a build mysteriously stops working, because of a
completely unrelated plugin.
This is pretty painful because
- it's possible to get into a 'no solution', where one project relies on one
behaviour so can't upgrade, and one project relies on new behaviour, so can't
downgrade.
- you get builds that work OK in isolation, but not in their project. This is
bad. Also builds tied together in bigger aggregator projects can fail in
mysterious ways (mysterious because the user /has/ specified the plugin
version, and maven has ignored them, or it's a plugin dependency that got there
first)
- subtle build ordering changes can cause new failures (the example has B
depend on A - but the bug might only manifest itself in certain build orders
that change even when B and A don't).
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