swift234

Start emitting stubs for unimplemented designated initializers of the superclass.

When a subclass does not implement a designated initializer of its
superclass, introduce a stub initializer that simply traps. Such stubs
cannot be invoked directly using Swift syntax, but can be invoked
through the Objective-C runtime and from Objective-C code. Catch such
errors rather than allowing them to violate the memory safety of the
language.

Note that we're currently using cond_fail to trap; this will be
improved in the future,


Swift SVN r14839