[MCHECKSTYLE-387] Deprecate method setUpCheckstyleClassloader in 3.1.2

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.1
• Fix Version/s: 3.1.2
• Assignee: Benjamin Marwell
• Reporter: Benjamin Marwell
• Created: 30/Dec/19 09:30
• Updated: 24/Jan/21 14:19
• Resolved: 07/Dec/20 14:58

Description

Current situation

In 3.1.1, the PR https://github.com/apache/maven-checkstyle-plugin/pull/18 added a try-catch-block to the to-be-removed method call Checker::setClassLoader.

Since users should be encuraged to upgrade and maven-plugin-developers should know that this method should be removed some time, a warning is to be issued if the method call was successful (i.e. when not entering the catch block).

Caveat and drawbacks

• Users will have to update their checkstyle.xml file because of incompatible changes introduced in 8.24. 
• Otherwise the warning might confuse users.
• Once the method call to Checker::setClassLoader is removed, checkstyle versions prior to 8.26 (Source: https://checkstyle.org/releasenotes.html#Release_8.26) cannot be used anymore (Source: https://github.com/checkstyle/checkstyle/commit/145160f5e21b80c27dc93a1904fe33b9afd4f212 and https://github.com/checkstyle/checkstyle/issues/3773). But this issue is not about removing this method call any time soon.
  => it will probably work fine for any 8.x version because this method existed for a deprecated check only.

Related issues

• [MCHECKSTYLE-381|https://issues.apache.org/jira/projects/MCHECKSTYLE/issues/MCHECKSTYLE-381] The mentioned previous commit.
• [MCHECKSTYLE-384|https://issues.apache.org/jira/projects/MCHECKSTYLE/issues/MCHECKSTYLE-384]: Once this maven-checkstyle-plugin updates to checkstyle > 8.24, the default installation for users will break existing installations unless users use this method of downgrading their checkstyle version: https://maven.apache.org/plugins/maven-checkstyle-plugin/examples/upgrading-checkstyle.html. 
• Also track https://github.com/checkstyle/checkstyle/issues/7190. This will tell when the checkstyle team removes that method.

Documentation

• maven-checkstyle-plugin is compatible with all checkstyle versions by functionality.
• maven-checkstyle-plugin >= 3.1.2 will complain if checkstyle < 8.29 is being used, which is the default (since it requires checkstyle 8.19).
• If we are ever going to remove the method Checker::setClassLoader, this means that earlier versions than checkstyle 8.26 are not supported. They will probably work just fine, but the method call became a 'real' no-op in 8.26. Might be worth documentation.

 

Issue Links

• links to: GitHub Pull Request #28