[issue42725] PEP 563: Should the behavior change for yield/yield from's

[Guido van Rossum]

Guido van Rossum <guido at python.org> added the comment:

So shouldn't we just rule out some specific bits of syntax in annotations? That can be done after the PEG grammar has accepted them, otherwise we'd end up having a whole new expression-like grammar section that excludes them. I think this is the list we should exclude, right?

- yield [from]
- walrus
- await (?)

I agree await technically doesn't need to be in this list, so maybe we shouldn't explicitly exclude it -- it's no different than writing

def f(x: open(filename).read()):
    ...

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