Implement Bug 46698, making ODS synthesize a getType() method that returns a
specific C++ class for OneResult methods where we know that class. This eliminates
a common source of casts in things like:
because we know that myOp always returns a FIRRTLType. This also encourages
op authors to type their results more tightly (which is also good for
I chose to implement this by splitting the OneResult trait into itself plus a
OneTypedResult trait, given that many things are using hasTrait<OneResult>
to conditionalize various logic.
While this changes makes many many ops get more specific getType() results, it
is generally drop-in compatible with the previous behavior because 'x.cast<T>()'
is allowed when x is already known to be a T. The one exception to this is that
we need declarations of the types used by ops, which is why a couple headers
needed additional #includes.
I updated a few things in tree to remove the now-redundant .cast<>'s, but there
are probably many more than can be removed.