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Allow explicit #[repr(Rust)]
#114201
Allow explicit #[repr(Rust)]
#114201
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The change itself & the implementation look good to me.
However, this looks like an insta-stable change, so I'll nominate for discussion in T-compiler
meeting. Question for the meeting: does this addition make sense/do we want to add it insta-stably?
Yeah I didn't put it behind a feature gate as it seems small enough, not really something that'd need further work after the PR that adds it. Also not really something imo that wouldn't want to be supported in the far future. Though if not I'm ok with putting it behind one |
This is T-lang and not T-compiler. |
@Centri3 to be clear: I don't think this should be behind a feature gate, just don't want to do this decision myself 😅 |
@rfcbot merge |
Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members: Concerns:
Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up! cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns. |
We say "a @rfcbot reviewed |
🔔 This is now entering its final comment period, as per the review above. 🔔 |
I remember being honestly surprised when I tried this and it didn't work. 😂 |
Isn't currently Maybe |
Is that so? I wasn't entirely sure so I allowed it there. Even if they're basically equivalent we should change it if I will test this once I get the chance to with Actually though, if |
That may be the case now but it looks like we don't guarantee it:
Given that we don't make any guarantees about what |
Forgive the bikeshed, but I'd like to propose that we reserve Even if you don't think that's a good idea, the reference has a name for what we're calling I know people use @rfcbot concern but-repr-rust-is-free-real-estate |
The final comment period, with a disposition to merge, as per the review above, is now complete. As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed. This will be merged soon. |
With FCP being complete, |
☀️ Test successful - checks-actions |
Finished benchmarking commit (4354192): comparison URL. Overall result: ✅ improvements - no action needed@rustbot label: -perf-regression Instruction countThis is a highly reliable metric that was used to determine the overall result at the top of this comment.
Max RSS (memory usage)ResultsThis is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
CyclesResultsThis is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
Binary sizeThis benchmark run did not return any relevant results for this metric. Bootstrap: 629.602s -> 631.442s (0.29%) |
This is the next upgrade to the Rust toolchain, from 1.73.0 to 1.74.1 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4 ("rust: upgrade to Rust 1.68.2"). # Unstable features No unstable features (that we use) were stabilized. Therefore, the only unstable features allowed to be used outside the `kernel` crate are still `new_uninit,offset_of`, though other code to be upstreamed may increase the list (e.g. `offset_of` was added recently). Please see [3] for details. # Other improvements Rust 1.74.0 allows to use `#[repr(Rust)]` explicitly [4], which can be useful to be explicit about particular cases that would normally use e.g. the C representation, such as silencing lints like the upcoming additions we requested [5] to the `no_mangle_with_rust_abi` Clippy lint (which in turn triggered the `#[repr(Rust)]` addition). Rust 1.74.0 includes a fix for one of the false negative cases we reported in Clippy's `disallowed_macros` lint [6] that we would like to use in the future. Rust 1.74.1 fixes an ICE that the Apple AGX GPU driver was hitting [7]. # Required changes For this upgrade, no changes were required (i.e. on our side). # `alloc` upgrade and reviewing The vast majority of changes are due to our `alloc` fork being upgraded at once. There are two kinds of changes to be aware of: the ones coming from upstream, which we should follow as closely as possible, and the updates needed in our added fallible APIs to keep them matching the newer infallible APIs coming from upstream. Instead of taking a look at the diff of this patch, an alternative approach is reviewing a diff of the changes between upstream `alloc` and the kernel's. This allows to easily inspect the kernel additions only, especially to check if the fallible methods we already have still match the infallible ones in the new version coming from upstream. Another approach is reviewing the changes introduced in the additions in the kernel fork between the two versions. This is useful to spot potentially unintended changes to our additions. To apply these approaches, one may follow steps similar to the following to generate a pair of patches that show the differences between upstream Rust and the kernel (for the subset of `alloc` we use) before and after applying this patch: # Get the difference with respect to the old version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > old.patch git -C linux restore rust/alloc # Apply this patch. git -C linux am rust-upgrade.patch # Get the difference with respect to the new version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > new.patch git -C linux restore rust/alloc Now one may check the `new.patch` to take a look at the additions (first approach) or at the difference between those two patches (second approach). For the latter, a side-by-side tool is recommended. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1741-2023-12-07 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: Rust-for-Linux#2 [3] Link: rust-lang/rust#114201 [4] Link: rust-lang/rust-clippy#11219 [5] Link: rust-lang/rust-clippy#11431 [6] Link: rust-lang/rust#117976 (comment) [7] Signed-off-by: Miguel Ojeda <[email protected]>
This is the next upgrade to the Rust toolchain, from 1.73.0 to 1.74.1 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4 ("rust: upgrade to Rust 1.68.2"). # Unstable features No unstable features (that we use) were stabilized. Therefore, the only unstable features allowed to be used outside the `kernel` crate are still `new_uninit,offset_of`, though other code to be upstreamed may increase the list (e.g. `offset_of` was added recently). Please see [3] for details. # Other improvements Rust 1.74.0 allows to use `#[repr(Rust)]` explicitly [4], which can be useful to be explicit about particular cases that would normally use e.g. the C representation, such as silencing lints like the upcoming additions we requested [5] to the `no_mangle_with_rust_abi` Clippy lint (which in turn triggered the `#[repr(Rust)]` addition). Rust 1.74.0 includes a fix for one of the false negative cases we reported in Clippy's `disallowed_macros` lint [6] that we would like to use in the future. Rust 1.74.1 fixes an ICE that the Apple AGX GPU driver was hitting [7]. # Required changes For this upgrade, no changes were required (i.e. on our side). # `alloc` upgrade and reviewing The vast majority of changes are due to our `alloc` fork being upgraded at once. There are two kinds of changes to be aware of: the ones coming from upstream, which we should follow as closely as possible, and the updates needed in our added fallible APIs to keep them matching the newer infallible APIs coming from upstream. Instead of taking a look at the diff of this patch, an alternative approach is reviewing a diff of the changes between upstream `alloc` and the kernel's. This allows to easily inspect the kernel additions only, especially to check if the fallible methods we already have still match the infallible ones in the new version coming from upstream. Another approach is reviewing the changes introduced in the additions in the kernel fork between the two versions. This is useful to spot potentially unintended changes to our additions. To apply these approaches, one may follow steps similar to the following to generate a pair of patches that show the differences between upstream Rust and the kernel (for the subset of `alloc` we use) before and after applying this patch: # Get the difference with respect to the old version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > old.patch git -C linux restore rust/alloc # Apply this patch. git -C linux am rust-upgrade.patch # Get the difference with respect to the new version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > new.patch git -C linux restore rust/alloc Now one may check the `new.patch` to take a look at the additions (first approach) or at the difference between those two patches (second approach). For the latter, a side-by-side tool is recommended. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1741-2023-12-07 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: #2 [3] Link: rust-lang/rust#114201 [4] Link: rust-lang/rust-clippy#11219 [5] Link: rust-lang/rust-clippy#11431 [6] Link: rust-lang/rust#117976 (comment) [7] Signed-off-by: Miguel Ojeda <[email protected]> Reviewed-by: Alice Ryhl <[email protected]> Reviewed-by: Martin Rodriguez Reboredo <[email protected]> Link: https://lore.kernel.org/r/[email protected]
This is the next upgrade to the Rust toolchain, from 1.73.0 to 1.74.1 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4 ("rust: upgrade to Rust 1.68.2"). # Unstable features No unstable features (that we use) were stabilized. Therefore, the only unstable features allowed to be used outside the `kernel` crate are still `new_uninit,offset_of`, though other code to be upstreamed may increase the list (e.g. `offset_of` was added recently). Please see [3] for details. # Other improvements Rust 1.74.0 allows to use `#[repr(Rust)]` explicitly [4], which can be useful to be explicit about particular cases that would normally use e.g. the C representation, such as silencing lints like the upcoming additions we requested [5] to the `no_mangle_with_rust_abi` Clippy lint (which in turn triggered the `#[repr(Rust)]` addition). Rust 1.74.0 includes a fix for one of the false negative cases we reported in Clippy's `disallowed_macros` lint [6] that we would like to use in the future. Rust 1.74.1 fixes an ICE that the Apple AGX GPU driver was hitting [7]. # Required changes For this upgrade, no changes were required (i.e. on our side). # `alloc` upgrade and reviewing The vast majority of changes are due to our `alloc` fork being upgraded at once. There are two kinds of changes to be aware of: the ones coming from upstream, which we should follow as closely as possible, and the updates needed in our added fallible APIs to keep them matching the newer infallible APIs coming from upstream. Instead of taking a look at the diff of this patch, an alternative approach is reviewing a diff of the changes between upstream `alloc` and the kernel's. This allows to easily inspect the kernel additions only, especially to check if the fallible methods we already have still match the infallible ones in the new version coming from upstream. Another approach is reviewing the changes introduced in the additions in the kernel fork between the two versions. This is useful to spot potentially unintended changes to our additions. To apply these approaches, one may follow steps similar to the following to generate a pair of patches that show the differences between upstream Rust and the kernel (for the subset of `alloc` we use) before and after applying this patch: # Get the difference with respect to the old version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > old.patch git -C linux restore rust/alloc # Apply this patch. git -C linux am rust-upgrade.patch # Get the difference with respect to the new version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > new.patch git -C linux restore rust/alloc Now one may check the `new.patch` to take a look at the additions (first approach) or at the difference between those two patches (second approach). For the latter, a side-by-side tool is recommended. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1741-2023-12-07 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: Rust-for-Linux/linux#2 [3] Link: rust-lang/rust#114201 [4] Link: rust-lang/rust-clippy#11219 [5] Link: rust-lang/rust-clippy#11431 [6] Link: rust-lang/rust#117976 (comment) [7] Signed-off-by: Miguel Ojeda <[email protected]> Reviewed-by: Alice Ryhl <[email protected]> Reviewed-by: Martin Rodriguez Reboredo <[email protected]> Link: https://lore.kernel.org/r/[email protected]
This is the next upgrade to the Rust toolchain, from 1.73.0 to 1.74.1 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4 ("rust: upgrade to Rust 1.68.2"). # Unstable features No unstable features (that we use) were stabilized. Therefore, the only unstable features allowed to be used outside the `kernel` crate are still `new_uninit,offset_of`, though other code to be upstreamed may increase the list (e.g. `offset_of` was added recently). Please see [3] for details. # Other improvements Rust 1.74.0 allows to use `#[repr(Rust)]` explicitly [4], which can be useful to be explicit about particular cases that would normally use e.g. the C representation, such as silencing lints like the upcoming additions we requested [5] to the `no_mangle_with_rust_abi` Clippy lint (which in turn triggered the `#[repr(Rust)]` addition). Rust 1.74.0 includes a fix for one of the false negative cases we reported in Clippy's `disallowed_macros` lint [6] that we would like to use in the future. Rust 1.74.1 fixes an ICE that the Apple AGX GPU driver was hitting [7]. # Required changes For this upgrade, no changes were required (i.e. on our side). # `alloc` upgrade and reviewing The vast majority of changes are due to our `alloc` fork being upgraded at once. There are two kinds of changes to be aware of: the ones coming from upstream, which we should follow as closely as possible, and the updates needed in our added fallible APIs to keep them matching the newer infallible APIs coming from upstream. Instead of taking a look at the diff of this patch, an alternative approach is reviewing a diff of the changes between upstream `alloc` and the kernel's. This allows to easily inspect the kernel additions only, especially to check if the fallible methods we already have still match the infallible ones in the new version coming from upstream. Another approach is reviewing the changes introduced in the additions in the kernel fork between the two versions. This is useful to spot potentially unintended changes to our additions. To apply these approaches, one may follow steps similar to the following to generate a pair of patches that show the differences between upstream Rust and the kernel (for the subset of `alloc` we use) before and after applying this patch: # Get the difference with respect to the old version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > old.patch git -C linux restore rust/alloc # Apply this patch. git -C linux am rust-upgrade.patch # Get the difference with respect to the new version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > new.patch git -C linux restore rust/alloc Now one may check the `new.patch` to take a look at the additions (first approach) or at the difference between those two patches (second approach). For the latter, a side-by-side tool is recommended. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1741-2023-12-07 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: Rust-for-Linux#2 [3] Link: rust-lang/rust#114201 [4] Link: rust-lang/rust-clippy#11219 [5] Link: rust-lang/rust-clippy#11431 [6] Link: rust-lang/rust#117976 (comment) [7] Reviewed-by: Martin Rodriguez Reboredo <[email protected]> Reviewed-by: Alice Ryhl <[email protected]> Reviewed-by: Benno Lossin <[email protected]> Tested-by: David Gow <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Miguel Ojeda <[email protected]>
Pkgsrc changes: * Remove NetBSD-8 support (embedded LLVm requires newer C++ than what is in -8; it's conceivable that this could still build with an external LLVM) * undo powerpc 9.0 file naming tweak, since we no longer support -8. * Remove patch to LLVM for powerpc now included by upstream. * Minor adjustments, checksum changes etc. Upstream changes: Version 1.74.1 (2023-12-07) =========================== - [Resolved spurious STATUS_ACCESS_VIOLATIONs in LLVM] (rust-lang/rust#118464) - [Clarify guarantees for std::mem::discriminant] (rust-lang/rust#118006) - [Fix some subtyping-related regressions] (rust-lang/rust#116415) Version 1.74.0 (2023-11-16) ========================== Language -------- - [Codify that `std::mem::Discriminant<T>` does not depend on any lifetimes in T] (rust-lang/rust#104299) - [Replace `private_in_public` lint with `private_interfaces` and `private_bounds` per RFC 2145] (rust-lang/rust#113126) Read more in [RFC 2145](https://rust-lang.github.io/rfcs/2145-type-privacy.html). - [Allow explicit `#[repr(Rust)]`] (rust-lang/rust#114201) - [closure field capturing: don't depend on alignment of packed fields] (rust-lang/rust#115315) - [Enable MIR-based drop-tracking for `async` blocks] (rust-lang/rust#107421) Compiler -------- - [stabilize combining +bundle and +whole-archive link modifiers] (rust-lang/rust#113301) - [Stabilize `PATH` option for `--print KIND=PATH`] (rust-lang/rust#114183) - [Enable ASAN/LSAN/TSAN for `*-apple-ios-macabi`] (rust-lang/rust#115644) - [Promote loongarch64-unknown-none* to Tier 2] (rust-lang/rust#115368) - [Add `i686-pc-windows-gnullvm` as a tier 3 target] (rust-lang/rust#115687) Libraries --------- - [Implement `From<OwnedFd/Handle>` for ChildStdin/out/err] (rust-lang/rust#98704) - [Implement `From<{&,&mut} [T; N]>` for `Vec<T>` where `T: Clone`] (rust-lang/rust#111278) - [impl Step for IP addresses] (rust-lang/rust#113748) - [Implement `From<[T; N]>` for `Rc<[T]>` and `Arc<[T]>`] (rust-lang/rust#114041) - [`impl TryFrom<char> for u16`] (rust-lang/rust#114065) - [Stabilize `io_error_other` feature] (rust-lang/rust#115453) - [Stabilize the `Saturating` type] (rust-lang/rust#115477) - [Stabilize const_transmute_copy] (rust-lang/rust#115520) Stabilized APIs --------------- - [`core::num::Saturating`] (https://doc.rust-lang.org/stable/std/num/struct.Saturating.html) - [`impl From<io::Stdout> for std::process::Stdio`] (https://doc.rust-lang.org/stable/std/process/struct.Stdio.html#impl-From%3CStdout%3E-for-Stdio) - [`impl From<io::Stderr> for std::process::Stdio`] (https://doc.rust-lang.org/stable/std/process/struct.Stdio.html#impl-From%3CStderr%3E-for-Stdio) - [`impl From<OwnedHandle> for std::process::Child{Stdin, Stdout, Stderr}`] (https://doc.rust-lang.org/stable/std/process/struct.Stdio.html#impl-From%3CStderr%3E-for-Stdio) - [`impl From<OwnedFd> for std::process::Child{Stdin, Stdout, Stderr}`] (https://doc.rust-lang.org/stable/std/process/struct.Stdio.html#impl-From%3CStderr%3E-for-Stdio) - [`std::ffi::OsString::from_encoded_bytes_unchecked`] (https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.from_encoded_bytes_unchecked) - [`std::ffi::OsString::into_encoded_bytes`] (https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.into_encoded_bytes) - [`std::ffi::OsStr::from_encoded_bytes_unchecked`] (https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.from_encoded_bytes_unchecked) - [`std::ffi::OsStr::as_encoded_bytes`] (https://doc.rust-lang.org/stable/std/ffi/struct.OsStr.html#method.as_encoded_bytes) - [`std::io::Error::other`] (https://doc.rust-lang.org/stable/std/io/struct.Error.html#method.other) - [`impl TryFrom<char> for u16`] (https://doc.rust-lang.org/stable/std/primitive.u16.html#impl-TryFrom%3Cchar%3E-for-u16) - [`impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T>`] (https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#impl-From%3C%26%5BT;+N%5D%3E-for-Vec%3CT,+Global%3E) - [`impl<T: Clone, const N: usize> From<&mut [T; N]> for Vec<T>`] (https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#impl-From%3C%26mut+%5BT;+N%5D%3E-for-Vec%3CT,+Global%3E) - [`impl<T, const N: usize> From<[T; N]> for Arc<[T]>`] (https://doc.rust-lang.org/stable/std/sync/struct.Arc.html#impl-From%3C%5BT;+N%5D%3E-for-Arc%3C%5BT%5D,+Global%3E) - [`impl<T, const N: usize> From<[T; N]> for Rc<[T]>`] (https://doc.rust-lang.org/stable/std/rc/struct.Rc.html#impl-From%3C%5BT;+N%5D%3E-for-Rc%3C%5BT%5D,+Global%3E) These APIs are now stable in const contexts: - [`core::mem::transmute_copy`] (https://doc.rust-lang.org/beta/std/mem/fn.transmute_copy.html) - [`str::is_ascii`] (https://doc.rust-lang.org/beta/std/primitive.str.html#method.is_ascii) - [`[u8]::is_ascii`] (https://doc.rust-lang.org/beta/std/primitive.slice.html#method.is_ascii) Cargo ----- - [fix: Set MSRV for internal packages] (rust-lang/cargo#12381) - [config: merge lists in precedence order] (rust-lang/cargo#12515) - [fix(update): Clarify meaning of --aggressive as --recursive] (rust-lang/cargo#12544) - [fix(update): Make `-p` more convenient by being positional] (rust-lang/cargo#12545) - [feat(help): Add styling to help output ] (rust-lang/cargo#12578) - [feat(pkgid): Allow incomplete versions when unambigious] (rust-lang/cargo#12614) - [feat: stabilize credential-process and registry-auth] (rust-lang/cargo#12649) - [feat(cli): Add '-n' to dry-run] (rust-lang/cargo#12660) - [Add support for `target.'cfg(..)'.linker`] (rust-lang/cargo#12535) - [Stabilize `--keep-going`] (rust-lang/cargo#12568) - [feat: Stabilize lints] (rust-lang/cargo#12648) Rustdoc ------- - [Add warning block support in rustdoc] (rust-lang/rust#106561) - [Accept additional user-defined syntax classes in fenced code blocks] (rust-lang/rust#110800) - [rustdoc-search: add support for type parameters] (rust-lang/rust#112725) - [rustdoc: show inner enum and struct in type definition for concrete type] (rust-lang/rust#114855) Compatibility Notes ------------------- - [Raise minimum supported Apple OS versions] (rust-lang/rust#104385) - [make Cell::swap panic if the Cells partially overlap] (rust-lang/rust#114795) - [Reject invalid crate names in `--extern`] (rust-lang/rust#116001) - [Don't resolve generic impls that may be shadowed by dyn built-in impls] (rust-lang/rust#114941) Internal Changes ---------------- These changes do not affect any public interfaces of Rust, but they represent significant improvements to the performance or internals of rustc and related tools. None this cycle.
Gate `repr(Rust)` correctly on non-ADT items rust-lang#114201 added `repr(Rust)` but didn't add any attribute validation to it like `repr(C)` has, to only allow it on ADT items. I consider this code to be nonsense, for example: ``` #[repr(Rust)] fn foo() {} ``` Reminder that it's different from `extern "Rust"`, which *is* valid on function items. But also this now disallows `repr(Rust)` on modules, impls, traits, etc. I'll crater it, if it looks bad then I'll add an FCW.
Gate `repr(Rust)` correctly on non-ADT items rust-lang#114201 added `repr(Rust)` but didn't add any attribute validation to it like `repr(C)` has, to only allow it on ADT items. I consider this code to be nonsense, for example: ``` #[repr(Rust)] fn foo() {} ``` Reminder that it's different from `extern "Rust"`, which *is* valid on function items. But also this now disallows `repr(Rust)` on modules, impls, traits, etc. I'll crater it, if it looks bad then I'll add an FCW. --- https://github.com/rust-lang/rust/labels/relnotes: Compatibility (minor breaking change).
Gate `repr(Rust)` correctly on non-ADT items rust-lang#114201 added `repr(Rust)` but didn't add any attribute validation to it like `repr(C)` has, to only allow it on ADT items. I consider this code to be nonsense, for example: ``` #[repr(Rust)] fn foo() {} ``` Reminder that it's different from `extern "Rust"`, which *is* valid on function items. But also this now disallows `repr(Rust)` on modules, impls, traits, etc. I'll crater it, if it looks bad then I'll add an FCW. --- https://github.com/rust-lang/rust/labels/relnotes: Compatibility (minor breaking change).
Rollup merge of rust-lang#129422 - compiler-errors:repr-rust, r=fmease Gate `repr(Rust)` correctly on non-ADT items rust-lang#114201 added `repr(Rust)` but didn't add any attribute validation to it like `repr(C)` has, to only allow it on ADT items. I consider this code to be nonsense, for example: ``` #[repr(Rust)] fn foo() {} ``` Reminder that it's different from `extern "Rust"`, which *is* valid on function items. But also this now disallows `repr(Rust)` on modules, impls, traits, etc. I'll crater it, if it looks bad then I'll add an FCW. --- https://github.com/rust-lang/rust/labels/relnotes: Compatibility (minor breaking change).
This is identical to no
repr()
at all. ForRust, packed
andRust, align(x)
, it should be the same as noRust
at all (as, afaik,#[repr(align(16))]
uses the Rust ABI.)The main use case for this is being able to explicitly say "I want to use the Rust ABI" in very very rare circumstances where the first obvious choice would be the C ABI yet is undesirable, which is already possible with functions as
extern "Rust"
. This would be useful for silencing rust-lang/rust-clippy#11253. It's also more consistent withextern
.The lack of this also tripped me up a bit when I was new to Rust, as I expected this to be possible.