Spinoff of LUCENE-5325.
Trivial patch. Literally no other changes need to be made anywhere in the codebase other than adding the throws statement to the method declaration in LeafFieldComparator.
Updated patch - this needed a change to SimpleFieldComparator as well, and changes to solr's CollapsingQParserPlugin
Commit 16b1db4e99c018b8c9507cf0f62a79e56484d6c0 in lucene-solr's branch refs/heads/branch_6x from Alan Woodward
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=16b1db4 ]
LUCENE-7607: FieldLeafComparator.setScorer() should throw IOException
Commit 87b6c2c8fcdc3a5f4adc3516f249af89b479d77a in lucene-solr's branch refs/heads/master from Alan Woodward
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=87b6c2c ]