I have this:
Enable ant's debug logging:
$ ant -h
ant [options] [target [target2 [target3] ...]]
Options:
...
-verbose, -v be extra verbose
-debug, -d print debugging information
Note though that this will generate a ton of output, so it may be best to capture the output to a file and then find the fileset info in a text editor:
ant -debug compile > ant-out.txt