Yury Selivanov wrote:

While we want "yield from" to have semantics close to a function call,

That's not what I said! I said that "yield from foo()" should
have semantics close to a function call. If you separate the
"yield from" from the "foo()", then of course you can get
different behaviours.

But that's beside the point, because I'm not suggesting
that generators should behave differently depending on when
or if you use "yield from" on them.

For (1) we want the context change to be isolated.  For (2) you say
that the context change should propagate to the caller.

No, I'm saying that the context change should *always*
propagate to the caller, unless you do something explicit
within the generator to prevent it.

I have some ideas on what that something might be, which
I'll post later.