Sergey Sprogis reports:

generated/adfiles/formssel.cpp source failed with the following message.

line 3845: Error: Deleting an object of polymorphic type MatchNode which doesn't have a virtual destructor may be unsafe.

Initially, I filed bug 16985917 under BugDB against C++, but Steve closed it with the resolution:

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Not a compiler bug, but a problem in the user code. At the line in question,
an object of type MatchNode is deleted, which is a polymorphic type not
having a virtual destructor. Such code is dangerous, and the compiler now
warns about it. The code is compiled with -errwarn, which converts warnings
into errors.

The source code should be fixed so that the base type, class Form, has a
virtual destructor.