LOGBACK-796 RollingFileAppender should have error when File matches FileNamePattern

[The-Alchemist]

Why

Ceki said:

File property and the archived files should not point to the same
file path. When you wish them to point to the same path, then File
property should be omitted.

From http://mailman.qos.ch/pipermail/logback-user/2013-January/003655.html

I've added the code / test for this.

What

• I've logged the issue at http://jira.qos.ch/browse/LOGBACK-796
• I wasn't sure where to add the check, but I added it to RollingFileAppender.start() because that's where other checks where (as opposed to RollingPolicyBase, where it seemed like the checks should be)
• I wanted to make the least changes to the code, so I didn't want to add the concept of validation to file name patterns.
• The additional test went into RollingFileAppenderTest
• All tests in logback-core (except Scala tests) still pass. :)

Other

Feedback, comments, etc. welcome.

[The-Alchemist]

I'm not sure whether I covered all the situations, or whether my validation logic is even correct.

I'm just doing a regex comparison to see if File matches FileNamePattern, which is OK but has some limitations:

• if File is x-1000.log and the file name pattern is x-%d{yyyy}.log, there technically shouldn't be problems because the system clock will (hopefully) never be set to the year 1000. However, the regex will match and with this pull request, logback will error out. I'm not sure if a loggin framework should be /that/ smart, though.