kv::std_support may not need value-bag

[tisonkun]

Exclude value-bag from the dependency tree when we don't need it.

The code would still leverage value-bag if it is enabled, thanks to the Value inner design.

cc @KodrAus

[tisonkun]

We may implement this for the non-value-bag Value. But that can be a follow-up.

[KodrAus]

We basically shouldn’t depend on kv_std anywhere except where it’s actually needed. It’s just an unfortunate workaround for not being able to activate Cargo features in a dependency based on the presence of multiple other features.

[tisonkun]

@KodrAus I remembered #657 .. Let me see if this makes some different.

[tisonkun]

@KodrAus I believe the issue is std = ["value-bag?/std"] but now we don't have that anymore.

[tisonkun]

That is, I test this PR locally to exclude value-bag from my dependency tree and it works well.

[KodrAus]

If I remember correctly, part of the issue too was we couldn’t use a combination of dep: and ? in our MSRV. Now that it’s raised we might be able to do that now.

We can continue to follow up with those kinds of improvements though. This specific change is still a step forwards.

[KodrAus]

Thanks @tisonkun

[tisonkun]

@KodrAus Thanks for your review and merging!

I'd appreciate it if you could test it (locally?) to prevent a regression to #661 and cut a release if it works well :D

I can move to that version downstream then. So far I'm patching in Cargo.toml to use a git dep.

[KodrAus]

I think we're ok there because we aren't adding any dependencies based on the presence of std here.