GitHub user josephw opened a pull request:

https://github.com/apache/maven/pull/51

MNG-5297: Mark <prerequisites> as deprecated.

MNG-4840 indicates that the Enforcer plugin should be
preferred to <prerequisites>. Indicate that in the documentation.

You can merge this pull request into a Git repository by running:

$ git pull https://github.com/josephw/maven MNG-5297-mark-prerequisites-maven-as-deprecated

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/maven/pull/51.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #51

commit c307e4ec0cb9997b20fc4aa67eefa836986fc484
Author: Joseph Walton <joe@kafsemo.org>
Date: 2015-06-11T15:32:38Z

MNG-5297: Mark <prerequisites> as deprecated.

MNG-4840 indicates that the Enforcer plugin should be
preferred to <prerequisites>. Indicate that in the documentation.

Github user kwin commented on a diff in the pull request:

https://github.com/apache/maven/pull/51#discussion_r32460741

— Diff: maven-model/src/main/mdo/maven.mdo —
@@ -3459,6 +3459,7 @@
<type>String</type>
<defaultValue>2.0</defaultValue>
<description><![CDATA[
+ <b>Deprecated</b>. Use the Maven Enforcer Plugin's <a href="https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html"><code>requireMavenVersion</code></a> rule instead.<br>
— End diff –

This <prerequisites> is still supported for Maven Plugins (https://issues.apache.org/jira/browse/MNG-5501?focusedCommentId=14419813&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14419813), therefore rather than deprecating that I would add a hint, that this should only be used for packaging "plugin".

Github user mosabua commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-112198560

Enforcer plugin is for build time enforcement. Prerequisite is build time as well as plugin runtime requirement. As such it should not be deprecated. Documentation update would however be useful.

Github user josephw commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-112843851

@kwin , @mosabua: thanks. I've rewritten it to reflect that distinction, that it's only deprecated for compile-time enforcement.

Github user josephw commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138286028

@kwin, @mosabua - is this current form acceptable as a fix?

Github user jvanzyl commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138295450

No. The enforcer plugin is for build-time enforcement. The <prerequisite/> element is for runtime enforcement. We certainly don't want to have to inspect the any plugin configuration elements to help Maven know that the current environment won't run the plugin. Also, if we ever get around to having the build vs consumption POM this information would not be available at all.

Github user josephw commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138297080

@jvanzyl although the original change was unconditional deprecation, I changed it after comments so the current language in the patch is intended to reflect that distinction:

> For a plugin project, the minimum version of Maven required to use
the resulting plugin.
> For specifying the minimum version of Maven required to build a project, this element is <b>deprecated</b>.

My intention here is to make clear that it's deprecated for some purposes.

Github user jvanzyl commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138297887

I'm reasonably sure it's never been used for build-time enforcement. Anything to make it clear that the enforcer is for build-time and the prerequisite element is for runtime is good.

Github user josephw commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138302328

Even if it wasn't the intended use, way back in Maven 2:

<prerequisites>
<maven>4</maven>
</prerequisites>

would give:

$ mvn2 validate
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Unable to build project '/tmp/pom.xml; it requires Maven version 4

The current language in the documentation is still:

The minimum version of Maven required to build the project.

so I think this PR clarifies the current intent.

Github user jvanzyl commented on the pull request:

https://github.com/apache/maven/pull/51#issuecomment-138307685

Fair enough, I cannot remember that far back

Github user asfgit closed the pull request at:

https://github.com/apache/maven/pull/51

ABORTED: Integrated in maven-3.x #1113 (See https://builds.apache.org/job/maven-3.x/1113/)
MNG-5297: Mark <prerequisites> as deprecated for compile-time enforcement. (jason: rev a839e55e7e5e057be2dafbd9eb1ebfb82d7598ed)

• pom.xml
• maven-model/src/main/mdo/maven.mdo

fixed model comment in 37c3f57f which caused site generation failure

Fixed in a839e55e7e5e057be2dafbd9eb1ebfb82d7598ed

SUCCESS: Integrated in Jenkins build maven-3.x #1374 (See https://builds.apache.org/job/maven-3.x/1374/)
MNG-5297 improved explanations on prerequisites.maven in Maven 3 (hboutemy: rev 950a90ececca385f60c336814fb8a48c3b42bb54)

• (edit) maven-model/src/main/mdo/maven.mdo

950a90ececca385f60c336814fb8a48c3b42bb54 is missing on post-reset-master.

FAILURE: Integrated in Jenkins build maven-3.x #1545 (See https://builds.apache.org/job/maven-3.x/1545/)
MNG-5297 improved explanations on prerequisites.maven in Maven 3 (hboutemy: http://git-wip-us.apache.org/repos/asf/?p=maven.git&a=commit&h=19d5b9dfa108a94c0825215a013ac21253cb0a17)

• (edit) maven-model/src/main/mdo/maven.mdo