Make #[naked] an unsafe attribute

[folkertdev]

tracking issue: #138997

Per #134213 (comment), the #[naked] attribute is now an unsafe attribute (in any edition).

This can only be merged when the above PRs are merged, I'd just like to see if there are any CI surprises here, and maybe there is early review feedback too.

r? @traviscross

[folkertdev]

Hmm, how should this this error be resolved?

error: unsafe attribute used without unsafe
##[error]   --> /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/compiler_builtins-0.1.153/src/macros.rs:436:15
    |
436 |               #[naked]
    |                 ^^^^^ usage of unsafe attribute
    |
   ::: /cargo/registry/src/index.crates.io-1949cf8c6b5b557f/compiler_builtins-0.1.153/src/x86_64.rs:10:1
    |
10  | / intrinsics! {
11  | |     #[naked]
12  | |     #[cfg(all(
13  | |         any(
...   |
42  | | }
    | |_- in this macro invocation
    |
    = note: this error originates in the macro `intrinsics` (in Nightly builds, run with -Z macro-backtrace for more info)
help: wrap the attribute in `unsafe(...)`
    |
436 |             #[unsafe(naked)]
    |               +++++++     +

It's kind of a cyclic dependency: I can't update the compiler without updating compiler-builtins, but I can't update compiler builtins either without an updated compiler. What is the right approach here?

[traviscross]

Does #[cfg_attr(bootstrap, ..)] (docs) work here?

[bors]

☔ The latest upstream changes (presumably #139766) made this pull request unmergeable. Please resolve the merge conflicts.

[folkertdev]

I thought that would not work because of the error that was emitted earlier (something with building miri), but it actually does appear to work (or at least, we get a different error now).

@bjorn3 do you see a way to work around the latest error? apparently a compiler where cfg(bootstrap) is true is used to run the mini_core_hello_world cranelift test?

[bjorn3]

That shouldn't happen. cg_clif should be tested using a stage1 rustc.

[folkertdev]

well, the #[cfg(bootstrap)] thing does not work after all. So I think the only viable solution is to allow but not require unsafe(naked) for a brief period, so that compiler-builtins can be updated.

[rustbot]

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred in src/doc/unstable-book/src/compiler-flags/sanitizer.md

cc @rust-lang/project-exploit-mitigations, @rcvalle

This PR modifies run-make tests.

cc @jieyouxu

[tgross35]

r=me once CI passes, unless you want to take a more thorough look @traviscross

[tgross35]

Actually, would you mind also updating the diagnostic message mentions of #[naked] in compiler/rustc_passes/messages.ftl and compiler/rustc_builtin_macros/messages.ftl?

[traviscross]

r=me also when CI passes, or I'll r= when I see that.

[traviscross]

@bors r=tgross35,traviscross rollup

[bors]

📌 Commit 41ddf86 has been approved by tgross35,traviscross

It is now in the queue for this repository.