Grails keeps rebuilding classes

I found an interesting problem today after replacing my laptop. My Grails 1.2.2 application that ran fine on Friday wasn't running today on 1.3.1 and the new machine.

I thought it was a 1.3.1 issue, but it wasn't. Turns out that if you have a file under src/groovy NOT grails-app AND the filename isn't the name of a class within the file, Grails will keep rebuilding the source file and clearing the Tomcat cache.

basically, I had a file 'GroupByCreator.groovy' which didn't have a class named "GroupByCreator" in it. For some reason IntelliJ doesn't complain and everything compiled correctly.

Instead at runtime I kept getting:

[groovyc] Compiling 1 source file to C:\Development\clouds\reportingui\target\classes

[groovyc] Compiling 2 source files to C:\Development\clouds\reportingui\target\classes

[delete] Deleting directory C:\Documents and Settings\ccurtin\.grails\1.3.1\projects\reportingui\tomcat

Running Grails application..
Server running. Browse to http://localhost:8080/reportingui

[groovyc] Compiling 1 source file to C:\Development\clouds\reportingui\target\classes

[groovyc] Compiling 2 source files to C:\Development\clouds\reportingui\target\classes

[delete] Deleting directory C:\Documents and Settings\ccurtin\.grails\1.3.1\projects\reportingui\tomcat

Running Grails application..
Server running. Browse to http://localhost:8080/reportingui

To figure this out, I went to the \reportingui\target\classes directory and sorted by last modified time. From that it was obvious which classes were being rebuilt, just not why. Finally after looking at the name of the file and the classes (for a few hours Doh!) I figured it out.

Arrgh.