PEP 255: Simple Generators, Revised Posting

[Tim Peters]

def emptyg():
    return
    yield None  # never reached

[Bernhard Herzog]
> Only until the compiler becomes smart enough to remove
> that unreachable yield statement. :)

[Rainer Deyke]
> By that time, the compiler will hopefully be smart enough to
> perform static analysis *before* removing dead code.

[Skip Montanaro]
> My peephole optimizer would have removed it...

That's OK:  the yield has no *runtime* purpose there, it's only being used
as a signal to the compiler to set the CO_GENERATOR flag in the code
object's co_code member.

Under the covers, generator code objects and bytecode are exactly the same
as for non-generators, except for that flag bit.  So code that "looks dead"
is just as dead as before <wink>.  There's nothing magic about RETURN_VALUE
in a generator's bytecode either.  In fact, eval_frame() knows nothing about
generators (it never looks at the CO_GENERATOR flag).