std: make a lot of items crate private by pacak · Pull Request #161612 · rust-lang/rust

pacak · 2026-08-23T17:37:36Z

Enabled warn(unreachable_pub)
Made a lot of things crate private, to the point when doing more required adding exceptions
Removed warn(unreachable_pub)

So now this commit just tightens the current visibility without trying to enforce it.

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r? clarfonthey

clarfonthey · 2026-08-23T19:32:29Z

So, looking at this, I'm going to nominate this for discussion alongside the clippy lints PR: #161328

Since they should go together, I think.

@rustbot label:I-libs-nominated

pacak · 2026-08-23T19:52:32Z

Sure.

Please no more obscure platform failures, please no more obscure platform failures, please no more obscure platform failures, please no more obscure platform failures...

clarfonthey · 2026-08-26T21:09:29Z

So, I forgot to say the verdict from our meeting yesterday, which is everyone is cool with me making the call on this as a reviewer. We do have this turned on for core and alloc, so, I think it would be fine to keep the lint enabled here but maybe explicitly allow the lint for the os and sys modules as this makes it more of a mess.

Feel free to also allow the lint for any modules you find particularly annoying. We seem to have a standard of trying to keep it on by default and just allowing it for annoying bits.

rustbot · 2026-08-26T21:42:48Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

pacak · 2026-08-26T23:10:07Z

It's alive!!!

clarfonthey · 2026-08-26T23:57:44Z

So, you still have a few changes inside the sys and os modules: were you hoping to keep those, or?

pacak · 2026-08-27T00:31:39Z

Right now I see them as "it was improved, but it is not enforced by clippy". I can probably go though a few iterations of whack-a-mole and enforce some more of them if you think its worth it. Probably tomorrow or something.

clarfonthey · 2026-08-27T00:37:57Z

I mostly mention it in the sense of, I figure if we're going to allow the lint for these modules, we probably shouldn't commit any of the changes for them, but I don't care too much either way. Mostly just curious if you had a compelling reason for it.

Most of them don't need to be public, but there are scenarios where thing is private on one platform but public on the other, so having a lint on all the time gets complicated. I enabled the lint, made a lot of things private to the point that dealing with the rest required adding exceptions and disabled the lint back again.

pacak · 2026-08-27T14:10:57Z

So I ended up enabling the lint explicitly on Windows and Linux. This way stuff not used by obscure platforms that still needs to be public can stay public.

As for removing changes to files where the lint is not enforced - I think there are benefits to leave them as is - the goal is to have less stuff public after all.

6-BennyLi-9 · 2026-08-27T14:33:36Z

Making some of the pub mod as pub(crate) mod is a good idea. But in my POV, we should lead the API alone. It may breaks Backward Compatibility rules,. Nobody knows if someone uses the API, then this pr may break the code.

pacak · 2026-08-27T15:15:27Z

Hmmm... Well, this PR started after I noticed some pub items inside of a non-pub module that wasn't reexported otherwise (unreachable pub). In my case this was producing error messages about potentially conflicting instances except that the type was strictly implementation detail and was not exported anywhere outside of the private module it was declared in, I checked.

Every pub(crate) here originates from a clippy complaining about pub(crate) being unreachable.

To break the code something needs to be used privately on both Linux and Windows, but needs to be visible outside of the crate via pub mod. Reexports won't work - it will fail to compile. For that you need to declare the same file mod twice with different visibility flags depending on a platform.

I did this

rg '^(pub |pub\(crate\) |)?mod \w+;' library/std

and don't see any.

Are there any specific scenarios you are worried about?

rustbot added the O-unix Operating system: Unix-like label Aug 23, 2026

rustbot assigned clarfonthey Aug 23, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Aug 23, 2026