deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead #135003

RalfJung · 2025-01-01T19:26:10Z

The rustc_allowed_through_unstable_modules attribute lets users call std::mem::transmute as std::intrinsics::transmute. The former is a reexport of the latter, and for a long time we didn't properly check stability for reexports, so making this a hard error now would be a breaking change for little gain. But at the same time, std::intrinsics::transmute is not the intended path for this function, so I think it is a good idea to show a deprecation warning when that path is used. This PR implements that, for all the functions in std::intrinsics that carry the attribute.

I assume this will need @rust-lang/libs-api FCP.

rustbot · 2025-01-01T19:26:18Z

r? @petrochenkov

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rustbot · 2025-01-01T19:26:20Z

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @rust-lang/wg-const-eval

RalfJung · 2025-01-01T19:27:16Z

compiler/rustc_passes/src/stability.rs

+                    // our own kind of error.
+                    let parents = path.segments.iter().rev().skip(1);
+                    for path_segment in parents {
+                        if let Some(def_id) = path_segment.res.opt_def_id() {


This is an unfortunate duplication of the loop above, but I didn't find a good way to deduplicate that code.

rustbot · 2025-01-01T19:46:38Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

RalfJung · 2025-01-01T19:47:18Z

compiler/rustc_middle/src/middle/stability.rs

+    // Skip all that work if the lint is allowed anyway.
+    if tcx.lint_level_at_node(lint, hir_id).0 == Level::Allow {
+        return;
+    }


This first commit is unrelated, it just moves some logic to what I think is a more sensible location. I thought I'd use that logic for this PR but in the end I did not. I can make this a separate PR if you prefer.

petrochenkov · 2025-01-02T14:14:46Z

r? compiler

…h-unstable-modules-is-a-deprecation-flag, r=GuillaumeGomez rustdoc: treat `allowed_through_unstable_modules` as deprecation This ensures `std::intrinsics::transmute` is deemphasized in the search engine and other UI, by cleaning it into a deprecation without propagating it through reexports when the parent module is stable. Fixes rust-lang#131676 Related to rust-lang#135003 r? `@GuillaumeGomez` `@RalfJung` `@workingjubilee`

…h-unstable-modules-is-a-deprecation-flag, r=GuillaumeGomez rustdoc: treat `allowed_through_unstable_modules` as deprecation This ensures `std::intrinsics::transmute` is deemphasized in the search engine and other UI, by cleaning it into a deprecation without propagating it through reexports when the parent module is stable. Fixes rust-lang#131676 Related to rust-lang#135003 r? ``@GuillaumeGomez`` ``@RalfJung`` ``@workingjubilee``

Rollup merge of rust-lang#135043 - notriddle:notriddle/allowed-through-unstable-modules-is-a-deprecation-flag, r=GuillaumeGomez rustdoc: treat `allowed_through_unstable_modules` as deprecation This ensures `std::intrinsics::transmute` is deemphasized in the search engine and other UI, by cleaning it into a deprecation without propagating it through reexports when the parent module is stable. Fixes rust-lang#131676 Related to rust-lang#135003 r? ``@GuillaumeGomez`` ``@RalfJung`` ``@workingjubilee``

fee1-dead · 2025-01-04T09:44:39Z

library/core/src/intrinsics/mod.rs

+#[cfg_attr(
+    not(bootstrap),
+    rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"
+)]


Suggested change

#[cfg_attr(

not(bootstrap),

rustc_allowed_through_unstable_modules = "import this function via `std::mem` instead"

)]

#[cfg_attr(

not(bootstrap),

rustc_allowed_through_unstable_modules(deprecated = "import this function via `std::mem` instead")

)]

I have no idea how to implement that with reasonable effort, sorry. This is a rustc-internal attribute so it doesn't have to be super pretty.

compiler/rustc_attr_data_structures/src/stability.rs

…ge when the unstable module name is used

RalfJung · 2025-01-15T09:58:39Z

@bors r=davidtwco

bors · 2025-01-15T09:58:41Z

📌 Commit 7ae494a has been approved by davidtwco

It is now in the queue for this repository.

…-unstable, r=davidtwco deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead The `rustc_allowed_through_unstable_modules` attribute lets users call `std::mem::transmute` as `std::intrinsics::transmute`. The former is a reexport of the latter, and for a long time we didn't properly check stability for reexports, so making this a hard error now would be a breaking change for little gain. But at the same time, `std::intrinsics::transmute` is not the intended path for this function, so I think it is a good idea to show a deprecation warning when that path is used. This PR implements that, for all the functions in `std::intrinsics` that carry the attribute. I assume this will need `@rust-lang/libs-api` FCP.

…llaumeGomez Rollup of 6 pull requests Successful merges: - rust-lang#131806 (Treat other items as functions for the purpose of type-based search) - rust-lang#132654 (std: lazily allocate the main thread handle) - rust-lang#135003 (deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead) - rust-lang#135428 (rustdoc: Remove `AttributesExt` trait magic that added needless complexity) - rust-lang#135498 (Prefer lower `TraitUpcasting` candidates in selection) - rust-lang#135529 (remove outdated FIXME) r? `@ghost` `@rustbot` modify labels: rollup

…llaumeGomez Rollup of 6 pull requests Successful merges: - rust-lang#132654 (std: lazily allocate the main thread handle) - rust-lang#135003 (deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead) - rust-lang#135428 (rustdoc: Remove `AttributesExt` trait magic that added needless complexity) - rust-lang#135498 (Prefer lower `TraitUpcasting` candidates in selection) - rust-lang#135507 (TRPL: incorporate all backward-compatible Edition changes) - rust-lang#135529 (remove outdated FIXME) r? `@ghost` `@rustbot` modify labels: rollup

jdonszelmann · 2025-02-06T12:47:18Z

for future reference I'd have appreciated it if this PR got the A-attributes label since it changed rustc_attr_parsing which is being reworked.

RalfJung · 2025-02-06T14:52:53Z

I think rustbot has some auto labeling support based on which folders a PR changes. That sounds easier than relying on every PR author or reviewer to remember this.

jdonszelmann · 2025-02-06T14:55:23Z

it does, we just enabled that haha #136643

rustbot assigned petrochenkov Jan 1, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 1, 2025

rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Jan 1, 2025

RalfJung added the I-libs-api-nominated Nominated for discussion during a libs-api team meeting. label Jan 1, 2025

RalfJung commented Jan 1, 2025

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Reexported intrinsics show up in rustdoc intra-doc links instead of their proper paths #131676

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RalfJung force-pushed the deprecate-allowed-through-unstable branch from ed11ebe to 59c0265 Compare January 1, 2025 19:46

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RalfJung force-pushed the deprecate-allowed-through-unstable branch from 59c0265 to 722a4b8 Compare January 1, 2025 20:56

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RalfJung force-pushed the deprecate-allowed-through-unstable branch from 722a4b8 to 9d035c7 Compare January 1, 2025 21:25

RalfJung changed the title ~~allowed_through_unstable_modules: support showing a deprecation message when the unstable module name is used~~ deprecate std::intrinsics::transmute etc, use std::mem::* instead Jan 2, 2025

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notriddle mentioned this pull request Jan 2, 2025

rustdoc: treat allowed_through_unstable_modules as deprecation #135043

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late_report_deprecation: move fast-path closer to the core logic

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RalfJung force-pushed the deprecate-allowed-through-unstable branch from 9a80eff to ff97579 Compare January 15, 2025 08:36

RalfJung added 3 commits January 15, 2025 09:41

allowed_through_unstable_modules: support showing a deprecation messa…

cf0ab86

…ge when the unstable module name is used

intrinsics: deprecate calling them via the unstable std::intrinsics path

f1c95c9

show deprecation message in rustdoc, too

7ae494a

RalfJung force-pushed the deprecate-allowed-through-unstable branch from ff97579 to 7ae494a Compare January 15, 2025 08:41

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 15, 2025

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Rollup of 6 pull requests #135533

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GuillaumeGomez mentioned this pull request Jan 15, 2025

Rollup of 6 pull requests #135540

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bors merged commit 369d135 into rust-lang:master Jan 15, 2025
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RalfJung deleted the deprecate-allowed-through-unstable branch January 16, 2025 10:53

vDorst mentioned this pull request Feb 3, 2025

embassy-usb: fix core::intrinsics deprecate warning in nightly. embassy-rs/embassy#3841

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deprecate std::intrinsics::transmute etc, use std::mem::* instead #135003

deprecate std::intrinsics::transmute etc, use std::mem::* instead #135003

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deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead #135003

deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead #135003

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