Tracking Issue for fmt::Arguments::as_str()

[m-ou-se]

Tracking issue for fmt::Arguments::as_str() (#74056), gated by #![feature(fmt_as_str)].

[nikki-nn4]

I don't quite understand fmt internals, but Make fmt::Arguments::as_str() return a 'static str. seems unnecessarily restrictive. And it breaks runtime-fmt which depends on hidden apis e.g. Arguments::new_v1

[tesuji]

Arguments cannot be generated at runtime because it cannot safely be done. So as_str returns &'static str makes sense.

[sfackler]

I'd like to be able to use this in the log crate to correctly implement a codegen optimization that doesn't really work otherwise: rust-lang/log#446

@rfcbot fcp merge

[rfcbot]

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

• @Amanieu
• @BurntSushi
• @KodrAus
• @dtolnay
• @m-ou-se
• @sfackler
• @withoutboats

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!

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[BurntSushi]

This SGTM. One question though. Are we sure that the 'static bound will always be correct here?