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a,b = 2,3 and [a,b] = [2,3]

On Tue, Sep 3, 2019 at 5:53 PM Serhiy Storchaka <storchaka at gmail.com> wrote:
> 02.09.19 12:24, Chris Angelico ????:
> > But the curious difference happens in 3.7. I don't know what changed
> > to cause this, but from there on, the list gets built and then
> > unpacked.
> This was a side effect of moving the optimization for `x in [a, b]` from
> the peepholer to the AST optimizer.

Ah ha. Thank you.

Is it worth trying to reinstate that? On the one hand, there's no
reason to build the list, and this technically is a (performance)
regression. On the other hand, it's not code people actually write,
since you can do the same thing with a tuple and it IS optimized.