Add LowerExp and UpperExp implementations to NonZero

[rick-de-water]

Adds LowerExp and UpperExp trait implementations to NonZero, as discussed in rust-lang/libs-team#458.

I had to modify the macro to mark the new impls with a different rust version. Let me know if this is the right way to do it (first timer here!)

[rustbot]

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[scottmcm]

hmm, would it perhaps make sense to use a :meta matcher here?

That plus a repeat in the macro could allow something like

impl_nonzero_fmt!{
    #[stable(feature = "nonzero", since = "1.28.0")]
    Debug

    #[stable(feature = "nonzero", since = "1.28.0")]
    Display

    #[stable(feature = "nonzero_fmt_exp", since = "CURRENT_RUSTC_VERSION")]
    LowerExp
}

which I think would be nice to make it more obvious to people rging and such what the attributes are on.

[rick-de-water]

Updated the macro

[scottmcm]

While you're getting CI happy,
@rustbot author

Then please squash the commits and rustbot review it.

[rick-de-water]

Applied feedback and squashed commits, please
@rustbot review

[m-ou-se]

@rfcbot merge

See rust-lang/libs-team#458:

LowerExp and UpperExp format traits implementations are missing from the NonZero integer types. All other (Binary, *Hex, Octal, etc) have been implemented, so it looks like an oversight, especially since the integer primitives themselves do implement LowerExp and UpperExp.

[rfcbot]

Team member @m-ou-se has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[rfcbot]

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

[dtolnay]

Thanks!

[dtolnay]

@bors r+

[bors]

📌 Commit fead1d5 has been approved by dtolnay

It is now in the queue for this repository.

[bors]

⌛ Testing commit fead1d5 with merge 7028d93...