[Distutils] Fwd: Re: PEP 517 again

[Paul Moore]

On 25 August 2017 at 11:16, Thomas Kluyver <thomas at kluyver.me.uk> wrote:
>> I repeat my earlier comment here - do we have any actual cases where
>> we expect in-place wheel builds to *not* enforce the equivalence?
>
> Flit cannot strictly enforce it if it can't build an sdist: with the way
> I've chosen to do sdists, it's not possible to know what would be in an
> sdist in the case where we can't build one.

If it can't build a sdist then there's no opportunity for frontends to
fall back to sdist->wheel anyway, so that's not an issue[1].

It's only if sdist->wheel and direct wheel are both possible that
frontends have a choice, and I feel that we should mandate that
backends ensure that it doesn't matter which route the frontend
chooses.

Paul

[1] Excepting the case where the user modifies things to allow sdists
(e.g. by installing git) and expects to get the same result, which is
a quality of implementation point and I'm sure flit does its best to
get that right, so I'm not worried about that case.