Broaden the consequences of recursive TLS initialization #116172

joboet · 2023-09-26T10:59:20Z

This PR updates the documentation of LocalKey to clearly disallow the behaviour described in this comment. This allows using OnceCell for the lazy initialization of TLS variables, which panics on reentrant initialization instead of updating the value like TLS variables currently do.

@rustbot label +T-libs-api
r? @m-ou-se

m-ou-se · 2023-09-26T12:50:52Z

@rfcbot merge

This allows thread locals to be implemented as a OnceCell.

(Right now, the behavior is a bit weird: you can initialize a thread local twice (or more) by recursively using .with. So, a non-mutable thread local can have different values over its lifetime, which seems like a bug to me. See discussion starting here: #110897 (comment))

rfcbot · 2023-09-26T12:50:53Z

Team member @m-ou-se has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

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!

See this document for info about what commands tagged team members can give me.

rfcbot · 2023-10-05T17:24:28Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rfcbot · 2023-10-15T17:35:20Z

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.

dtolnay

Thank you!

dtolnay · 2023-10-15T17:42:03Z

@bors r+ rollup

bors · 2023-10-15T17:42:05Z

📌 Commit 559ec69 has been approved by dtolnay

It is now in the queue for this repository.

…n, r=dtolnay Broaden the consequences of recursive TLS initialization This PR updates the documentation of `LocalKey` to clearly disallow the behaviour described in [this comment](rust-lang#110897 (comment)). This allows using `OnceCell` for the lazy initialization of TLS variables, which panics on reentrant initialization instead of updating the value like TLS variables currently do. `@rustbot` label +T-libs-api r? `@m-ou-se`

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#115955 (Stabilize `{IpAddr, Ipv6Addr}::to_canonical`) - rust-lang#116033 (report `unused_import` for empty reexports even it is pub) - rust-lang#116172 (Broaden the consequences of recursive TLS initialization) - rust-lang#116341 (Implement sys::args for UEFI) - rust-lang#116522 (use `PatKind::Error` when an ADT const value has violation) - rust-lang#116732 (Make x capable of resolving symlinks) - rust-lang#116755 (Remove me from libcore review rotation) - rust-lang#116760 (Remove trivial cast in `guaranteed_eq`) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#116172 (Broaden the consequences of recursive TLS initialization) - rust-lang#116341 (Implement sys::args for UEFI) - rust-lang#116522 (use `PatKind::Error` when an ADT const value has violation) - rust-lang#116732 (Make x capable of resolving symlinks) - rust-lang#116755 (Remove me from libcore review rotation) - rust-lang#116760 (Remove trivial cast in `guaranteed_eq`) - rust-lang#116771 (Ignore let-chains formatting) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#116172 - joboet:recursive_tls_initialization, r=dtolnay Broaden the consequences of recursive TLS initialization This PR updates the documentation of `LocalKey` to clearly disallow the behaviour described in [this comment](rust-lang#110897 (comment)). This allows using `OnceCell` for the lazy initialization of TLS variables, which panics on reentrant initialization instead of updating the value like TLS variables currently do. ``@rustbot`` label +T-libs-api r? ``@m-ou-se``

Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * For an external LLVM, set dependency of llvm >= 16, in accordance with the upstream changes. * Mark that on NetBSD we now need >= 9.0, so 8.x is no longer supported. * On NetBSD/sparc64 10.x, we now need GCC 12 to build the embedded LLVM, which is version 17; apparently GCC 10.4 or 10.5 mis-compiles it, resulting in an illegal instruction fault during the build. Ref. rust-lang/rust#117231 Upstream changes: Version 1.75.0 (2023-12-28) ========================== - [Stabilize `async fn` and return-position `impl Trait` in traits.] (rust-lang/rust#115822) - [Allow function pointer signatures containing `&mut T` in `const` contexts.] (rust-lang/rust#116015) - [Match `usize`/`isize` exhaustively with half-open ranges.] (rust-lang/rust#116692) - [Guarantee that `char` has the same size and alignment as `u32`.] (rust-lang/rust#116894) - [Document that the null pointer has the 0 address.] (rust-lang/rust#116988) - [Allow partially moved values in `match`.] (rust-lang/rust#103208) - [Add notes about non-compliant FP behavior on 32bit x86 targets.] (rust-lang/rust#113053) - [Stabilize ratified RISC-V target features.] (rust-lang/rust#116485) Compiler -------- - [Rework negative coherence to properly consider impls that only partly overlap.] (rust-lang/rust#112875) - [Bump `COINDUCTIVE_OVERLAP_IN_COHERENCE` to deny, and warn in dependencies.] (rust-lang/rust#116493) - [Consider alias bounds when computing liveness in NLL.] (rust-lang/rust#116733) - [Add the V (vector) extension to the `riscv64-linux-android` target spec.] (rust-lang/rust#116618) - [Automatically enable cross-crate inlining for small functions] (rust-lang/rust#116505) - Add several new tier 3 targets: - [`csky-unknown-linux-gnuabiv2hf`] (rust-lang/rust#117049) - [`i586-unknown-netbsd`] (rust-lang/rust#117170) - [`mipsel-unknown-netbsd`] (rust-lang/rust#117356) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Override `Waker::clone_from` to avoid cloning `Waker`s unnecessarily.] (rust-lang/rust#96979) - [Implement `BufRead` for `VecDeque<u8>`.] (rust-lang/rust#110604) - [Implement `FusedIterator` for `DecodeUtf16` when the inner iterator does.] (rust-lang/rust#110729) - [Implement `Not, Bit{And,Or}{,Assign}` for IP addresses.] (rust-lang/rust#113747) - [Implement `Default` for `ExitCode`.] (rust-lang/rust#114589) - [Guarantee representation of None in NPO] (rust-lang/rust#115333) - [Document when atomic loads are guaranteed read-only.] (rust-lang/rust#115577) - [Broaden the consequences of recursive TLS initialization.] (rust-lang/rust#116172) - [Windows: Support sub-millisecond sleep.] (rust-lang/rust#116461) - [Fix generic bound of `str::SplitInclusive`'s `DoubleEndedIterator` impl] (rust-lang/rust#100806) - [Fix exit status / wait status on non-Unix `cfg(unix)` platforms.] (rust-lang/rust#115108) Stabilized APIs --------------- - [`Atomic*::from_ptr`] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.from_ptr) - [`FileTimes`] (https://doc.rust-lang.org/stable/std/fs/struct.FileTimes.html) - [`FileTimesExt`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTimesExt.html) - [`File::set_modified`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_modified) - [`File::set_times`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_times) - [`IpAddr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/enum.IpAddr.html#method.to_canonical) - [`Ipv6Addr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_canonical) - [`Option::as_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_slice) - [`Option::as_mut_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_mut_slice) - [`pointer::byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_add) - [`pointer::byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset) - [`pointer::byte_offset_from`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset_from) - [`pointer::byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_sub) - [`pointer::wrapping_byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_add) - [`pointer::wrapping_byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_offset) - [`pointer::wrapping_byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_sub) These APIs are now stable in const contexts: - [`Ipv6Addr::to_ipv4_mapped`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_ipv4_mapped) - [`MaybeUninit::assume_init_read`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.assume_init_read) - [`MaybeUninit::zeroed`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.zeroed) - [`mem::discriminant`] (https://doc.rust-lang.org/stable/core/mem/fn.discriminant.html) - [`mem::zeroed`] (https://doc.rust-lang.org/stable/core/mem/fn.zeroed.html) Cargo ----- - [Add new packages to `[workspace.members]` automatically.] (rust-lang/cargo#12779) - [Allow version-less `Cargo.toml` manifests.] (rust-lang/cargo#12786) - [Make browser links out of HTML file paths.] (rust-lang/cargo#12889) Rustdoc ------- - [Accept less invalid Rust in rustdoc.] (rust-lang/rust#117450) - [Document lack of object safety on affected traits.] (rust-lang/rust#113241) - [Hide `#[repr(transparent)]` if it isn't part of the public ABI.] (rust-lang/rust#115439) - [Show enum discriminant if it is a C-like variant.] (rust-lang/rust#116142) Compatibility Notes ------------------- - [FreeBSD targets now require at least version 12.] (rust-lang/rust#114521) - [Formally demote tier 2 MIPS targets to tier 3.] (rust-lang/rust#115238) - [Make misalignment a hard error in `const` contexts.] (rust-lang/rust#115524) - [Fix detecting references to packed unsized fields.] (rust-lang/rust#115583) - [Remove support for compiler plugins.] (rust-lang/rust#116412)

std: broaden the allowed behaviour for recursive TLS initialization

559ec69

rustbot assigned m-ou-se Sep 26, 2023

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. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Sep 26, 2023

m-ou-se removed the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Sep 26, 2023

rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Sep 26, 2023

m-ou-se added S-waiting-on-fcp Status: PR is in FCP and is awaiting for FCP to complete. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 26, 2023

rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Oct 5, 2023

dtolnay approved these changes Oct 15, 2023

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bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Oct 15, 2023

matthiaskrgr mentioned this pull request Oct 15, 2023

Rollup of 8 pull requests #116769

Closed

matthiaskrgr mentioned this pull request Oct 15, 2023

Rollup of 7 pull requests #116772

Merged

bors merged commit e063d8a into rust-lang:master Oct 15, 2023
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rustbot added this to the 1.75.0 milestone Oct 15, 2023

Veykril mentioned this pull request Oct 17, 2023

Pull upstream master 2023 10 17 ferrocene/ferrocene#54

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apiraino removed the to-announce Announce this issue on triage meeting label Oct 19, 2023

joboet deleted the recursive_tls_initialization branch December 29, 2023 10:42

dtolnay self-assigned this Mar 24, 2024

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Broaden the consequences of recursive TLS initialization #116172

Broaden the consequences of recursive TLS initialization #116172

joboet commented Sep 26, 2023

m-ou-se commented Sep 26, 2023 •

edited

rfcbot commented Sep 26, 2023 •

edited by BurntSushi

rfcbot commented Oct 5, 2023

rfcbot commented Oct 15, 2023

dtolnay left a comment

dtolnay commented Oct 15, 2023

bors commented Oct 15, 2023

Broaden the consequences of recursive TLS initialization #116172

Broaden the consequences of recursive TLS initialization #116172

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joboet commented Sep 26, 2023

m-ou-se commented Sep 26, 2023 • edited

rfcbot commented Sep 26, 2023 • edited by BurntSushi

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m-ou-se commented Sep 26, 2023 •

edited

rfcbot commented Sep 26, 2023 •

edited by BurntSushi