Stabilize naked_functions

[bstrie]

This stabilizes the feature described in RFC 2972, which supercedes the earlier RFC 1201.

Closes #32408
Closes #90957

[rust-highfive]

r? @davidtwco

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[davidtwco]

Implementation changes in this pull request looks good to me, it's ready for when the FCP over at #90957 (comment) resolves, assuming no new required changes come out of that process.

[bors]

☔ The latest upstream changes (presumably #94096) made this pull request unmergeable. Please resolve the merge conflicts.

[npmccallum]

@bstrie The FCP has now completed. Please update this PR.

[JohnTitor]

Ping from triage: @bstrie Could you resolve merge conflicts and make this PR ready? Thanks!

[dancrossnyc]

Another gentle ping here? It would be really nice to see this merged.

[pnkfelix]

Based on a quick skim, I think this is blocked on PR #93809, since we do not to stabilize the naked_function feature without first ensuring that we only have limited the set of attributes it can be used with to the subset that we are confident about.

[est31]

👋 Hello, I'm writing this comment in this stabilization PR to notify you, the authors of this PR, that #100591 has been merged, which implemented a change in how features are stabilized.

Your PR has been filed before the change, so will likely require modifications in order to comply with the new rules. I recommend you to:

1. rebase the PR onto latest master, so that uses of the placeholder are possible.
2. replace the version numbers in the PR with the placeholder CURRENT_RUSTC_VERSION. For language changes, this means the version numbers in accepted.rs (example: 4caedba). For library changes, this means the since fields (example e576a9b).

That's it! The CURRENT_RUSTC_VERSION placeholder will, as part of the release process, be replaced with the version number that the PR merged for. It can be used anywhere in rust-lang/rust, not just accepted.rs and the since fields.

If you have any questions, feel free to drop by the zulip stream, or ping me directly in this PR's thread. Thanks! 👋

[hudson-ayers]

With today's stabilization of asm_sym, I suspect this feature is one of the last remaining blockers of a move to stable Rust for lots of Rust firmware / OS development (I can say this is true for Tock). So any movement on this stabilization would be great!

(asm_const may still be a blocker for some, but IME it is much easier to approximate with hacks than naked_functions.)

[luojia65]

Mergeing this would definitely boost firmware development in Rust, I'm strongly agree to stabilize this feature. We may expect some reviews but will finally get there.

[Dylan-DPC]

Going to close this pr as it is blocked on another PR which is still a draft PR and hence this will stay blocked for a long time.

[dancrossnyc]

Out of curiosity, what's the other PR?

[Lokathor]

It was linked a few comments up: #93809

Seems to be stalled since May

[dancrossnyc]

Ah, thanks.