Remove the #[no_sanitize] attribute in favor of #[sanitize(xyz = "on|off")]

[1c3t3a]

This came up during the sanitizer stabilization (#123617). Instead of a #[no_sanitize(xyz)] attribute, we would like to have a #[sanitize(xyz = "on|off")] attribute, which is more powerful and allows to be extended in the future (instead
of just focusing on turning sanitizers off). The implementation is done according to what was discussed on Zulip).

The new attribute also works on modules, traits and impl items and thus enables usage as the following:

#[sanitize(address = "off")]
mod foo {
    fn unsanitized(..) {}

    #[sanitize(address = "on")]
    fn sanitized(..) {}
}

trait MyTrait {
  #[sanitize(address = "off")]
  fn unsanitized_default(..) {}
}

#[sanitize(thread = "off")]
impl MyTrait for () {
    ...
}

r? @rcvalle

[rustbot]

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol

triagebot.toml has been modified, there may have been changes to the review queue.

cc @davidtwco, @wesleywiser

Some changes occurred in src/doc/unstable-book/src/language-features/no-sanitize.md

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

Some changes occurred in tests/codegen/sanitizer

cc @rcvalle

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

Some changes occurred in compiler/rustc_codegen_ssa/src/codegen_attrs.rs

cc @jdonszelmann

[rcvalle]

Thank you very much for your time and work on this, @1c3t3a! Much appreciated.

[rcvalle]

cc @Darksonn @wesleywiser @traviscross

[Darksonn]

It doesn't matter for me, but should we make this change gradually by supporting both for some time?

[1c3t3a]

It doesn't matter for me, but should we make this change gradually by supporting both for some time?

That's possible for sure, I put stuff into different commits for that reason and I can just drop the middle commit to have both exist in parallel.

What's the reason for having both at the same time? An easier migration period?

[traviscross]

We generally do not make such efforts to migrate usage of nightly features without a specific known good reason to do so. (Let us know of course if there is one, e.g. if this affects RfL in some way.)

[bors]

☔ The latest upstream changes (presumably #142770) made this pull request unmergeable. Please resolve the merge conflicts.

[ojeda]

e.g. if this affects RfL in some way.

We don't use #[no_sanitize] in mainline (nor in -next) at the moment.

[1c3t3a]

I rebased the change to make review easier.

[jieyouxu]

Note that if this is a built-in attribute, then IIUC #[sanitize] (even if unstably gated) could introduce new name resolution ambiguities with user macros or derive macro attributes and thus technically break existing user code. See for instance #143834. cf. #134963.

// tests/ui/whatever_subdir/test.rs

//@ proc-macro: my_derive.rs
//@ edition: 2024

use my_derive::MyDerive;

#[derive(MyDerive)]
#[sanitize]
//~^ ERROR `sanitize` is ambiguous
pub struct Foo;

fn main() {}

// tests/ui/whatever_subdir/auxiliary/my_derive.rs

//@ edition: 2024

extern crate proc_macro;
use proc_macro::{Span, TokenStream};

#[proc_macro_derive(
    MyDerive,
    attributes(
        sanitize
    )
)]
pub fn derive_custom(_item: TokenStream) -> TokenStream {
    TokenStream::new()
}

You can still observe this for #[no_sanitize] too, if you switch sanitize for no_sanitize in the above test case.

error: malformed `no_sanitize` attribute input
  --> /home/joe/repos/rust/tests/ui/bitbuffer_derive/test.rs:7:1
   |
LL | #[no_sanitize]
   | ^^^^^^^^^^^^^^ help: must be of the form: `#[no_sanitize(address, kcfi, memory, thread)]`

error[E0659]: `no_sanitize` is ambiguous
  --> /home/joe/repos/rust/tests/ui/bitbuffer_derive/test.rs:7:3
   |
LL | #[no_sanitize]
   |   ^^^^^^^^^^^ ambiguous name
   |
   = note: ambiguous because of a name conflict with a builtin attribute
   = note: `no_sanitize` could refer to a built-in attribute

error[E0658]: the `#[no_sanitize]` attribute is an experimental feature
  --> /home/joe/repos/rust/tests/ui/bitbuffer_derive/test.rs:7:1
   |
LL | #[no_sanitize]
   | ^^^^^^^^^^^^^^
   |
   = note: see issue #39699 <https://github.com/rust-lang/rust/issues/39699> for more information
   = help: add `#![feature(no_sanitize)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0658, E0659.
For more information about an error, try `rustc --explain E0658`.

Or just

macro_rules! sanitize {
    () => {
        /* .. */
    };
}

pub(crate) use sanitize; // `use` here becomes ambiguous

fn main() {}

I imagine no_sanitize is much less likely to collide with something a user would write (not an argument against this change, just an observation re. technically a breaking change).

I don't know how much of a concern for breakage this is in practice, a crater run may or may not be a good idea. If the breakage is deemed acceptable, then this should get relnotes.

[bors]

☔ The latest upstream changes (presumably #143919) made this pull request unmergeable. Please resolve the merge conflicts.

[traviscross]

@rustbot labels +T-lang +needs-fcp
cc @rust-lang/lang

Given that this is breaking, we should review and FCP. Let's do that crater run, since we'll need it for our review.

@bors2 try

[rust-bors]

⌛ Trying commit a466546 with merge 4949cf2…

To cancel the try build, run the command @bors2 try cancel.

[traviscross]

Since this produces a user-visible effect on stable Rust, it feels like we should be documenting this somehow in the Reference. We'll talk about how we might want to do that on the lang-docs side.

cc @ehuss

[1c3t3a]

Given that this is breaking, we should review and FCP

Yes that sounds good. The initial idea of @rcvalle and me was to stabilize this together with the sanitizers in #123617. Does that make sense?

technically break existing user code.

Thanks a lot for the great summary @jieyouxu! I did a quick GH codesearch and found e.g. https://crates.io/crates/sanitizer which defines a sanitizer macro. How is the usual way of reacting to such name clashes?

[rust-bors]

☀️ Try build successful (CI)
Build commit: 4949cf2 (4949cf2f817beadb9a248d423b6d55d6d2398ffe, parent: cccf075eba88363269e8589ebb8d40874cc542d8)

[traviscross]

@craterbot check

[craterbot]

👌 Experiment pr-142681 created and queued.
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⚠️ Try build based on commit a466546, but latest commit is 9ee7903. Did you forget to make a new try build?
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