Re-export `core::fmt::NumBuffer` in `alloc` (and `std`) by cuviper · Pull Request #161430 · rust-lang/rust

cuviper · 2026-08-20T22:17:19Z

We just stabilized core::fmt::NumBuffer in Rust 1.98, but it seems to be a simple oversight that this was not also re-exported in alloc::fmt (and std just re-exports that whole module). Let's correct that.

I'm marking this stable right away, although I don't think the later since version will be properly rendered in docs for a re-export. I'm not sure it's worth trying to clarify that in freeform documentation.

rustbot · 2026-08-20T22:17:25Z

r? @JohnTitor

rustbot has assigned @JohnTitor.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: libs
libs expanded to 12 candidates
Random selection from JohnTitor, Mark-Simulacrum, clarfonthey, nia-e

hanna-kruppe · 2026-08-20T22:21:15Z

Yeah I'm pretty sure the version on the re-export will be wrong. We could reduce how wrong it is by backporting this to beta, if we care about reducing the odds that someone accidentally breaks their MSRV by using the std path.

hanna-kruppe · 2026-08-20T22:24:32Z

Let's do an FCP since it's new stable API surface, however trivial: @rfcbot fcp merge libs

Edit: welp, guess I'm not allowed?

hanna-kruppe · 2026-08-20T22:29:33Z

@rfcbot fcp merge libs

JohnTitor · 2026-08-20T22:42:53Z

I guess the recent libs reorg is involved?

Mark-Simulacrum · 2026-08-20T22:52:17Z

@rfcbot fcp merge libs

rust-rfcbot · 2026-08-20T22:52:19Z

@Mark-Simulacrum 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.

JohnTitor

r=me once FCP passes

View changes since this review

rust-rfcbot · 2026-09-01T15:59:12Z

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

rust-rfcbot · 2026-09-11T16:01:18Z

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.

hanna-kruppe · 2026-09-11T17:13:03Z

@bors r=JohnTitor rollup

rust-bors · 2026-09-11T17:13:06Z

📌 Commit dad850c has been approved by JohnTitor

It is now in the queue for this repository.

Re-export `core::fmt::NumBuffer` in `alloc` (and `std`) We just stabilized `core::fmt::NumBuffer` in Rust 1.98, but it seems to be a simple oversight that this was not also re-exported in `alloc::fmt` (and `std` just re-exports that whole module). Let's correct that. I'm marking this stable right away, although I don't think the later `since` version will be properly rendered in docs for a re-export. I'm not sure it's worth trying to clarify that in freeform documentation.

…uwer Rollup of 7 pull requests Successful merges: - #161413 (mir-transform: Remove `is_optimization_stage`) - #161430 (Re-export `core::fmt::NumBuffer` in `alloc` (and `std`)) - #162446 (Prevent `should-fail` to be used in `rustdoc-ui` testsuite) - #162621 (Clarify examples related to `Sync` and `SyncView`) - #162650 (Initialize mingw for all mingw targets) - #162651 (Remove needless test running instructions) - #162658 (Remove noras target docs mention)

Rollup merge of #161430 - cuviper:fmt_numbuffer, r=JohnTitor Re-export `core::fmt::NumBuffer` in `alloc` (and `std`) We just stabilized `core::fmt::NumBuffer` in Rust 1.98, but it seems to be a simple oversight that this was not also re-exported in `alloc::fmt` (and `std` just re-exports that whole module). Let's correct that. I'm marking this stable right away, although I don't think the later `since` version will be properly rendered in docs for a re-export. I'm not sure it's worth trying to clarify that in freeform documentation.

[beta] backports - Re-export `core::fmt::NumBuffer` in `alloc` (and `std`) #161430 - Make `VaArgSafe` dyn-incompatible #162374 - Destabilize `VaArgSafe` #162909 - attach global target features to module-level assembly #160594 - (partial) compiler-builtins subtree update - #162816 r? me

Pkgsrc changes: * Adapt to changes in vendored crate versions. * Version & checksum changes. Upstream changes: Version 1.99.0 (2026-10-01) ========================== Language -------- - [Add allow-by-default `raw_borrows_via_references` lint that checks for references that decay immediately into raw borrows](rust-lang/rust#138230) - [Extend `unconditional_panic` lint to function calls that panic when the chunks/windows size is zero] (rust-lang/rust#153563) - [Stabilize C-variadic function definitions] (rust-lang/rust#155697) - [Stabilize the ability to use `#[unsafe(naked)]` functions to define C-variadic functions (`#![feature(c_variadic_naked_functions)]`).] (rust-lang/rust#159746) - [Trait methods are now resolved on an adjusted never type (producing a FCW)] (rust-lang/rust#156047) - [Coerce from inference variables to trait objects if the inference variable is related via subtyping to a type that is known to be `Sized`] (rust-lang/rust#157820) - [Stabilize `#[my_macro] mod foo;`] (rust-lang/rust#157857). This allows outlined modules (`mod foo;`) anywhere in the body of a custom attribute or derive macro. - [Fix the `overflowing_literals` lint with repeated negation] (rust-lang/rust#158302). For instance, it will now no longer lint on `--128_i8`, which is already detected by the `arithmetic_overflow` lint. - [Add POSIX symbols to the `invalid_runtime_symbol_definitions` and `suspicious_runtime_symbol_definitions` lints] (rust-lang/rust#158522) - [Lint unused `#[path]` attributes on inline modules] (rust-lang/rust#158835) - [Enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group] (rust-lang/rust#159179) - [Stabilize passing 128-bit integers via vector registers with `asm!` on x86] (rust-lang/rust#159525) - [Explicitly document that some allocations are allowed to grow in-place (but none are allowed to shrink)] (rust-lang/rust#159729) - We now [guarantee] (rust-lang/rust#159730) that the contents of an `UnsafeCell` can be accessed without going through `get` - [The `invalid_reference_casting` lint was adjusted accordingly] (rust-lang/rust#159960) - [Account for globally enabled target features in `global_asm!`] (rust-lang/rust#160594) - [Warn if an invalid `doc` attribute is used on a macro invocation] (rust-lang/rust#161003) Compiler -------- - [Convert `-Ctarget-cpu` into a target-modifier for AVR, AMDGCN and NVPTX] (rust-lang/rust#150732) - [Enable `static_position_independent_executables` on all gnu and musl targets] (rust-lang/rust#158510) - When providing a suggestion about a missing method, rustc now prefers an exactly matching name from a [doc alias attribute] (https://doc.rust-lang.org/rustdoc/advanced-features.html#add-aliases-for-an-item-in-documentation-search) over a similarity search from other method names. If your new users sometimes expect a method under a different name, adding a doc alias will now help them find it via rustc suggestions, in addition to helping them find it via rustdoc search: [When suggesting method names, prefer *exact* doc aliases over similar names](rust-lang/rust#160369) Platform Support ---------------- - [Promote `riscv64-unknown-linux-musl` to Tier 2 with host tools] (rust-lang/rust#158766) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. [platform-support-doc]: https://doc.rust-lang.org/rustc/platform-support.html Libraries --------- - Iteration on `RangeInclusive` (`a..=b` ranges) is now [optimized better in some circumstances] (rust-lang/rust#155114). As a side effect of this, the behavior of `RangeInclusive` values that has already been exhausted (as an iterator) has changed. For example, the return values of `start()` and `end()` on such ranges may return different values, and using such ranges as slice indexes may have different behavior. These behaviors were not guaranteed to be stable, so these changes are considered to not be breaking changes. - [Relax `transmute_copy` to accept `?Sized` types] (rust-lang/rust#155989) - [Update `transmute_copy` to use a non-unwinding panic] (rust-lang/rust#155989) - [Don't escape U+FF9E and U+FF9F in `escape_debug_ext`] (rust-lang/rust#158057) - [Re-export `core::fmt::NumBuffer` in `alloc` (and `std`)] (rust-lang/rust#161430) Stabilized APIs --------------- - [`IntoIterator` for `Box<[T; N]>`] (https://doc.rust-lang.org/stable/std/iter/trait.IntoIterator.html#impl-IntoIterator-for-Box%3C%5BT;+N%5D,+A%3E) - [`IntoIterator` for `&Box<[T; N]>`] (https://doc.rust-lang.org/stable/std/iter/trait.IntoIterator.html#impl-IntoIterator-for-%26Box%3C%5BT;+N%5D,+A%3E) - [`IntoIterator` for `&mut Box<[T; N]>`] (https://doc.rust-lang.org/stable/std/iter/trait.IntoIterator.html#impl-IntoIterator-for-%26mut+Box%3C%5BT;+N%5D,+A%3E) - [`VecDeque::retain_back`] (https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.retain_back) - [`core::ffi::VaList`] (https://doc.rust-lang.org/stable/core/ffi/struct.VaList.html) - [`Box::into_non_null`] (https://doc.rust-lang.org/stable/std/boxed/struct.Box.html#method.into_non_null) - [`Box::from_non_null`] (https://doc.rust-lang.org/stable/std/boxed/struct.Box.html#method.from_non_null) - [`Vec::into_parts`] (https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.into_parts) - [`Vec::from_parts`] (https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.from_parts) - [`core::mem::size_of_val_raw`] (https://doc.rust-lang.org/stable/core/mem/fn.size_of_val_raw.html) - [`core::mem::align_of_val_raw`] (https://doc.rust-lang.org/stable/core/mem/fn.align_of_val_raw.html) - [`core::alloc::Layout::for_value_raw`] (https://doc.rust-lang.org/stable/core/alloc/struct.Layout.html#method.for_value_raw) - [`String::from_utf8_lossy_owned`] (https://doc.rust-lang.org/stable/std/string/struct.String.html#method.from_utf8_lossy_owned) - [`string::FromUtf8Error::into_utf8_lossy`] (https://doc.rust-lang.org/stable/std/string/struct.FromUtf8Error.html#method.into_utf8_lossy) - [`FusedIterator for StepBy<I>`] (https://doc.rust-lang.org/stable/std/iter/struct.StepBy.html#impl-FusedIterator-for-StepBy%3CI%3E) - [`std::fs::set_times`] (https://doc.rust-lang.org/stable/std/fs/fn.set_times.html) - [`std::fs::set_times_nofollow`] (https://doc.rust-lang.org/stable/std/fs/fn.set_times_nofollow.html) Cargo ----- - Add a new built-in profile `debug`. This is a preparation for transitioning the `dev` profile away from debugging to give a saner default for faster development iterations. Currently there is no difference between `dev` and `debug` profiles. [docs] (https://doc.rust-lang.org/nightly/cargo/reference/profiles.html#debug-1) [#17214] (rust-lang/cargo#17214) - Workspace members on edition 2024 or later can now override an inherited workspace dependency's `default-features` field. For example, `serde = { workspace = true, default-features = false }` now turns off default features even when the workspace definition enables them. On earlier editions, `default-features = false` is ignored with a warning. ([RFC 3945] (rust-lang/rfcs#3945)) [#17126](rust-lang/cargo#17126) - Incremental compilation is now disabled by default when running in CI. CI is detected via the CI environment variable. [#17220] (rust-lang/cargo#17220) See also the [full Cargo changelog] (https://doc.rust-lang.org/nightly/cargo/CHANGELOG.html#cargo-199-2026-10-01) Rustdoc ----- - [Add new `unused_footnote_definition` rustdoc lint] (rust-lang/rust#137858) - Smarter filtering of trait impls yields performance improvements of 20% on average and up to 40% on some real-world crates. ([1] (rust-lang/rust#159623), [2](rust-lang/rust#159721), [3](rust-lang/rust#159779), [4](rust-lang/rust#159854), [5](rust-lang/rust#159091)) Compatibility Notes ------------------- - [Fully deprecate the legacy integral modules] (rust-lang/rust#146882). For example, `std::i32::MAX` should be accessed via `i32::MAX` instead. - [Upgrade `no_mangle_generic_items` into hard error] (rust-lang/rust#154585) - [The `Pin::new_unchecked` has had its safety invariants changed slightly] (rust-lang/rust#156935) - [Do not promote references to extern statics] (rust-lang/rust#157641) - [Ensure that the inferred types of `let` patterns typecheck] (rust-lang/rust#157841) - [hermit/fs: Return `unsupported()` instead of `from_raw_os_error(22)`] (rust-lang/rust#158247) - [Fixed a bug where `#[repr(simd)]` was accidentally allowed on macro invocations on stable Rust] (rust-lang/rust#158523) - [Abort const-eval when there are generics in the type of the value being produced] (rust-lang/rust#159504) - [Attributes not applying to anything are now an error in code blocks in doc comments] (rust-lang/rust#159849) - [`Box::leak`: tell people to avoid unleaking] (rust-lang/rust#160323) - [PowerPC inline ASM: Fix scalar floats being in the wrong vector lane on little endian] (rust-lang/rust#160441) - [Do not take `doc(cfg())` into account when filtering doctests] (rust-lang/rust#159014) - [Infer anonymous lifetimes in the types of associated consts as `'static`] (rust-lang/rust#156508) - Macros that expand to a semicolon now produce a warning lint (`semicolon_in_expressions_from_non_local_macros`) even when the macro comes from another crate. Previously, such warnings only appeared for macros from the same crate, to avoid showing warnings that can't be fixed locally; however, this masked problems, as integration tests from the crate providing the macro get compiled as a separate crate, so tests often wouldn't reveal this issue. If you encounter a lint like this, please make sure to report it to the crate providing the macro so they can fix it; don't just silence it in your own crate. - [`semicolon_in_expressions_from_macros`: Lint on non-local macros too] (rust-lang/rust#159222) - [Split non-local `semicolon_in_expressions_from_macros` into a separate lint] (rust-lang/rust#159700) 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. - [Update to LLVM 23] (rust-lang/rust#158734)

cuviper added the needs-fcp This change is insta-stable, or significant enough to need a team FCP to proceed. label Aug 20, 2026

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 20, 2026

rustbot assigned JohnTitor Aug 20, 2026

rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Aug 20, 2026

This comment has been minimized.

Sign in to view

Re-export core::fmt::NumBuffer in alloc (and std)

dad850c

cuviper force-pushed the fmt_numbuffer branch from e134824 to dad850c Compare August 20, 2026 22:24

theemathas added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Aug 21, 2026

JohnTitor approved these changes Aug 27, 2026

View reviewed changes

JohnTitor 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 Aug 27, 2026

rust-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 Sep 1, 2026

nia-e added the beta-accepted Accepted for backporting to the compiler in the beta channel. label Sep 3, 2026

rustbot mentioned this pull request Sep 11, 2026

Tracking issue for release notes of #161430: Re-export core::fmt::NumBuffer in alloc (and std) #162649

Open

rust-bors Bot 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-review Status: Awaiting review from the assignee but also interested parties. labels Sep 11, 2026

This was referenced Sep 11, 2026

Rollup of 8 pull requests #162659

Closed

Rollup of 7 pull requests #162664

Merged

rust-bors Bot merged commit 5a64414 into rust-lang:main Sep 11, 2026
13 checks passed

rustbot added this to the 1.100.0 milestone Sep 11, 2026

cuviper mentioned this pull request Sep 18, 2026

[beta] backports #162987

Merged

cuviper modified the milestones: 1.100.0, 1.99.0 Sep 18, 2026

cuviper removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Sep 18, 2026

github-actions Bot mentioned this pull request Oct 2, 2026

Toolchain upgrade to nightly-2026-09-25 flux-rs/flux#1803

Merged

Navigation Menu

Uh oh!

Re-export `core::fmt::NumBuffer` in `alloc` (and `std`) - #161430

Re-export `core::fmt::NumBuffer` in `alloc` (and `std`)#161430
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
cuviper:fmt_numbuffer

cuviper commented Aug 20, 2026

Uh oh!

rustbot commented Aug 20, 2026

Uh oh!

hanna-kruppe commented Aug 20, 2026

Uh oh!

This comment has been minimized.

hanna-kruppe commented Aug 20, 2026 •

edited

Loading

Uh oh!

hanna-kruppe commented Aug 20, 2026

Uh oh!

JohnTitor commented Aug 20, 2026

Uh oh!

Mark-Simulacrum commented Aug 20, 2026

Uh oh!

rust-rfcbot commented Aug 20, 2026 •

edited by the8472

Loading

Uh oh!

JohnTitor left a comment •

edited by rustbot

Loading

Uh oh!

rust-rfcbot commented Sep 1, 2026

Uh oh!

rust-rfcbot commented Sep 11, 2026

Uh oh!

hanna-kruppe commented Sep 11, 2026

Uh oh!

rust-bors Bot commented Sep 11, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

9 participants

Uh oh!

Conversation

cuviper commented Aug 20, 2026

Uh oh!

rustbot commented Aug 20, 2026

Uh oh!

hanna-kruppe commented Aug 20, 2026

Uh oh!

This comment has been minimized.

hanna-kruppe commented Aug 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

hanna-kruppe commented Aug 20, 2026

Uh oh!

JohnTitor commented Aug 20, 2026

Uh oh!

Mark-Simulacrum commented Aug 20, 2026

Uh oh!

rust-rfcbot commented Aug 20, 2026 • edited by the8472 Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

JohnTitor left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

rust-rfcbot commented Sep 1, 2026

Uh oh!

rust-rfcbot commented Sep 11, 2026

Uh oh!

hanna-kruppe commented Sep 11, 2026

Uh oh!

rust-bors Bot commented Sep 11, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

9 participants

hanna-kruppe commented Aug 20, 2026 •

edited

Loading

rust-rfcbot commented Aug 20, 2026 •

edited by the8472

Loading

JohnTitor left a comment •

edited by rustbot

Loading