scala/scala — pull request #392 by som-snytt (2012-04-13 22:32:37+00:00)
Title: SI-5663: Tweak warnings on case class equals

Re-enable testing the sensibility of comparing instances
of two case classes. In particular, warn if we detect that
the two objects inherit from different case classes. In
addition, avoid emitting misleading warnings when comparing "new C".

I've put some thought into the test cases, but Paul will want to
review style and efficiency of the expressions in checkSensible.