[beta-1.91] Warn on future errors from temporary lifetimes shortening in Rust 1.92 #147056

dianne · 2025-09-26T09:43:26Z

Pursuant to discussion on Zulip, this implements a future-compatibility warning lint macro_extended_temporary_scopes for errors in Rust 1.92 caused by #145838:

warning: temporary lifetime shortening in Rust 1.92
  --> $DIR/macro-extended-temporary-scopes.rs:54:14
   |
LL |             &struct_temp().field
   |              ^^^^^^^^^^^^^ this expression creates a temporary value...
...
LL |         } else {
   |         - ...which will be dropped at the end of this block in Rust 1.92
   |
   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see <https://doc.rust-lang.org/rustc/lints/listing/warn-by-default.html#macro-extended-temporary-scopes>
   = note: consider using a `let` binding to create a longer lived value

Implementation-wise, this reuses the existing temporary scoping FCW machinery introduced for the tail_expr_drop_order edition lint: this adds BackwardIncompatibleDropHint statements to the MIR at the end of the shortened scopes for affected temporaries; these are then checked in borrowck to warn if the temporary is used after the future drop hint. There are trade-offs here: on one hand, I believe this gives some assurance over ad-hoc pattern-recognition that there are no false positives¹. On the other hand, this fails to lint on future dangling raw pointers and it complicates the potential addition of explanatory diagnostics or suggestions². I'm hopeful that the limitation around dangling pointers won't be relevant in real code, though; the only real instance we've seen of breakage so far is future errors in formatting macro invocations, which this should be able to catch.

Release logistics notes:

This PR targets the beta branch directly, since the breakage it's a FCW for is landing in the next Rust version.
Temporary lifetime extension for blocks #146098 undoes the breakage this is a FCW for. If that behavior is merged and stabilizes in Rust 1.92, this PR should be reverted (or shouldn't be merged) in order to avoid spurious warnings.

cc @traviscross

@rustbot label +T-lang

In particular, more syntactic approaches are complicated by having to avoid warning on promoted constants; they'd either be full of holes, they'd need a lot of extra logic, or they'd need to hack more MIR-to-HIR mapping into PromoteTemps. ↩
It's definitely possible to add more context and a suggestion, but the ways I've thought of to do so are either too hacky or too complex to feel appropriate for a last-minute direct-to-beta lint. ↩

rustbot · 2025-09-26T09:43:29Z

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @vakaras

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustbot · 2025-09-26T09:43:32Z

r? @davidtwco

rustbot has assigned @davidtwco.
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

dianne

A general note: since this isn't targeting master, I've included a fair bit of single-purpose code. It's possible some of the generalizations to BackwardIncompatibleDropHint handling would be good to have for future FCWs, but everything new is made to be one-off and temporary.

Also, a note about the ping for changing the MIR: I believe that's from adding another case to BackwardIncompatibleDropReason.

And about changing MIR transforms: that's from making the significant-drop-reordering part of tail_expr_drop_order only fire on BackwardIncompatibleDropReason::Edition2024. It already checks the edition, so I figure it makes sense to check the BackwardIncompatibleDropReason too.

View changes since this review

dianne · 2025-09-26T09:47:31Z

compiler/rustc_middle/src/thir.rs

-    static_assert_size!(Expr<'_>, 72);
+    static_assert_size!(Expr<'_>, 80);


I believe this should be avoidable. Let me know if it's worth trying to fix.

dianne · 2025-09-26T09:52:16Z

compiler/rustc_lint_defs/src/builtin.rs

+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseError,
+        reference: "<https://doc.rust-lang.org/rustc/lints/listing/warn-by-default.html#macro-extended-temporary-scopes>",
+    };


Ideally, the reference link shouldn't be tied to the lint's stabilization, but there's not currently a great reference that both includes a complete explanation of the breakage and how to work around it.

Also, I haven't included report_in_deps: true but since the breakage is hitting in the next version it might be warranted.

dianne · 2025-09-26T10:04:54Z

compiler/rustc_borrowck/src/diagnostics/mod.rs

+
+        tcx.node_span_lint(MACRO_EXTENDED_TEMPORARY_SCOPES, lint_root, labels, |diag| {
+            diag.primary_message("temporary lifetime shortening in Rust 1.92");
+            diag.note("consider using a `let` binding to create a longer lived value");


I've opted to use the "consider using a let binding" note from real borrowck diagnostics for simplicity, rather than providing a machine-applicable suggestion. To illustrate, consider real Rust 1.92 nightly diagnostics for the future breakage here:

error[E0716]: temporary value dropped while borrowed --> src/main.rs:18:13 | 18 | pin!({ &temp() }); | --------^^^^^---- | | | | | | | temporary value is freed at the end of this statement | | creates a temporary value which is freed while still in use | borrow later stored here | = note: consider using a `let` binding to create a longer lived value error[E0716]: temporary value dropped while borrowed --> src/main.rs:19:17 | 19 | pin!({ &mut [()] }); | -----^^^- | | | | | | | temporary value is freed at the end of this statement | | creates a temporary value which is freed while still in use | borrow later used here | = note: consider using a `let` binding to create a longer lived value

Note the differing spans. In many instances, the conflicting use reported in diagnostics is an implicit reborrow rather than the actual use in the macro expansion. I think getting more helpful diagnostics would either require:

Improving the actual borrowck diagnostic, then using that machinery.

Forcing maximal MIR-to-HIR mapping via source scopes when forward-incompatible drops are detected, then using bespoke diagnostic information stored earlier in compilation (e.g. the HIR source of forward-incompatible scope extension).

Another awkward aspect of that span imprecision is (without doing either of those things) it's hard to tell when adding a let statement actually can help. In non-pathological cases it should always either help or come with another note that the diagnostic originates in an external macro, so for simplicity, I've opted to always include it.

PatchMixolydic · 2025-09-27T18:02:58Z

compiler/rustc_borrowck/src/diagnostics/mod.rs

+        );
+
+        tcx.node_span_lint(MACRO_EXTENDED_TEMPORARY_SCOPES, lint_root, labels, |diag| {
+            diag.primary_message("temporary lifetime shortening in Rust 1.92");


This message seems like it'd be difficult to understand without context — to me, it almost seems like it's been cut off partway through. It might be better to be explicit here:

Suggested change

diag.primary_message("temporary lifetime shortening in Rust 1.92");

diag.primary_message("this temporary's lifetime will be shortened starting in Rust 1.92");

It is a bit difficult to understand as-is.. though I wonder if there's a way to write it without "this" in the primary message. My original take was "this temporary value's lifetime will shorten in Rust 1.92", but I moved away from it because something didn't feel right to me about the "this" and it felt redundant with the label. Maybe it would be fine?

How about temporary lifetime will be shortened in Rust 1.92? The current diagnostic is definitely awkward.

That does sound better. Applied: (diff)

rustbot · 2025-09-29T07:36:38Z

Some changes occurred in match lowering

cc @Nadrieril

dianne · 2025-09-29T07:37:57Z

I haven't adjusted the wording yet, but I did some renaming and I've added logic to also lint on shortening lifetimes for internal temporaries created by pin! and format_args!. These weren't initially caught since they're implemented in the compiler as local variables that follow temporary scoping rules (hence the match lowering change; that's where variables' drops are scheduled). This is much less likely to be relevant, but it's possible if someone was using format_args! with constant-promotable arguments in if branches in string formatting. e.g.

println!("{:?}{}",
    (),
    if true {
        format_args!("{:?}", Promotable)
    } else {
        format_args!("")
    }
);

It's a much more niche situation admittedly, but it compiles on stable/beta and not nightly (and it wasn't caught previously).

rustbot · 2025-09-29T08:04:10Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

davidtwco · 2025-09-29T12:21:42Z

r? @jackh726 who reviewed the original PR

jackh726 · 2025-09-29T16:58:20Z

I haven't looked at this too deeply yet, but my general initial thought is this is a lot of code changes for something that is only going to hit beta with no prior testing on nightly. It really concerns me, I'm not sure about other compiler folks.

samueltardieu

Clippy changes review: no concerns about the mechanical changes.

View changes since this review

jackh726 · 2025-10-01T03:18:15Z

Still haven't gotten to review this properly, but going to go ahead and add the nomination label to get a feel for what others think.

traviscross · 2025-10-01T15:30:22Z

We've decided to break this; we want to accept this one-version FCW, and we're waiving our 10-day final comment period.

Obviously it's compiler's call whether to accept the beta backport.

@rfcbot fcp merge

rust-rfcbot · 2025-10-01T15:30:24Z

Team member @traviscross 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!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

rust-rfcbot · 2025-10-11T15:31:24Z

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.

jackh726

Certainly not an "easy'" change, but looking through this, I don't see anything that strikes me as wrong.

I did leave a suggestion for the primary diagnostic, I think it needs to be changed to something else.

r=me with that change

View changes since this review

oli-obk · 2025-10-14T07:20:39Z

@bors r=jackh726

bors · 2025-10-14T07:20:42Z

📌 Commit 164620f has been approved by jackh726

It is now in the queue for this repository.

…r=jackh726 [beta-1.91] Warn on future errors from temporary lifetimes shortening in Rust 1.92 Pursuant to [discussion on Zulip](https://rust-lang.zulipchat.com/#narrow/channel/474880-t-compiler.2Fbackports/topic/.23145838.3A.20beta-nominated/near/540530631), this implements a future-compatibility warning lint `macro_extended_temporary_scopes` for errors in Rust 1.92 caused by #145838: ``` warning: temporary lifetime shortening in Rust 1.92 --> $DIR/macro-extended-temporary-scopes.rs:54:14 | LL | &struct_temp().field | ^^^^^^^^^^^^^ this expression creates a temporary value... ... LL | } else { | - ...which will be dropped at the end of this block in Rust 1.92 | = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see <https://doc.rust-lang.org/rustc/lints/listing/warn-by-default.html#macro-extended-temporary-scopes> = note: consider using a `let` binding to create a longer lived value ``` Implementation-wise, this reuses the existing temporary scoping FCW machinery introduced for the `tail_expr_drop_order` edition lint: this adds `BackwardIncompatibleDropHint` statements to the MIR at the end of the shortened scopes for affected temporaries; these are then checked in borrowck to warn if the temporary is used after the future drop hint. There are trade-offs here: on one hand, I believe this gives some assurance over ad-hoc pattern-recognition that there are no false positives[^1]. On the other hand, this fails to lint on future dangling raw pointers and it complicates the potential addition of explanatory diagnostics or suggestions[^2]. I'm hopeful that the limitation around dangling pointers won't be relevant in real code, though; the only real instance we've seen of breakage so far is future errors in formatting macro invocations, which this should be able to catch. Release logistics notes: - This PR targets the beta branch directly, since the breakage it's a FCW for is landing in the next Rust version. - #146098 undoes the breakage this is a FCW for. If that behavior is merged and stabilizes in Rust 1.92, this PR should be reverted (or shouldn't be merged) in order to avoid spurious warnings. cc `@traviscross` `@rustbot` label +T-lang [^1]: In particular, more syntactic approaches are complicated by having to avoid warning on promoted constants; they'd either be full of holes, they'd need a lot of extra logic, or they'd need to hack more MIR-to-HIR mapping into `PromoteTemps`. [^2]: It's definitely possible to add more context and a suggestion, but the ways I've thought of to do so are either too hacky or too complex to feel appropriate for a last-minute direct-to-beta lint.

bors · 2025-10-14T15:51:07Z

⌛ Testing commit 164620f with merge bcf11f6...

bors · 2025-10-14T16:05:06Z

💔 Test failed - checks-actions

rust-log-analyzer · 2025-10-14T16:07:05Z

A job failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[endgroup]
Image input checksum 8e79d7e45f937c70fac2b63c6b6ffbe2d31cebd810041883336e4081190720d30590134e0ed94621864ee317d38c2d32bd694bbf59291a13d32171cb91bf3131
##[group]Building docker image for x86_64-gnu-llvm-20
Docker version 28.0.4, build b8034c0
Error response from daemon: Get "https://ghcr.io/v2/": Get "https://ghcr.io/token?account=rust-lang&client_id=docker&offline_token=true&service=ghcr.io": context deadline exceeded (Client.Timeout exceeded while awaiting headers) (Client.Timeout exceeded while awaiting headers)
##[error]Process completed with exit code 1.
Post job cleanup.

cuviper · 2025-10-14T16:22:28Z

Look like a spurious network issue?

@bors retry

bors · 2025-10-15T01:35:51Z

⌛ Testing commit 164620f with merge df8b2e4...

bors · 2025-10-15T04:41:10Z

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing df8b2e4 to beta...

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [rust](https://github.com/rust-lang/rust) | minor | `1.90.0` -> `1.91.0` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>rust-lang/rust (rust)</summary> ### [`v1.91.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1910-2025-10-30) [Compare Source](rust-lang/rust@1.90.0...1.91.0) \========================== <a id="1.91.0-Language"></a> ## Language - [Lower pattern bindings in the order they're written and base drop order on primary bindings' order](rust-lang/rust#143764) - [Stabilize declaration of C-style variadic functions for `sysv64`, `win64`, `efiapi`, and `aapcs` ABIs](rust-lang/rust#144066). This brings these ABIs in line with the C ABI: variadic functions can be declared in extern blocks but not defined. - [Add `dangling_pointers_from_locals` lint to warn against dangling pointers from local variables](rust-lang/rust#144322) - [Upgrade `semicolon_in_expressions_from_macros` from warn to deny](rust-lang/rust#144369) - [Stabilize LoongArch32 inline assembly](rust-lang/rust#144402) - [Add warn-by-default `integer_to_ptr_transmutes` lint against integer-to-pointer transmutes](rust-lang/rust#144531) - [Stabilize `sse4a` and `tbm` target features](rust-lang/rust#144542) - [Add `target_env = "macabi"` and `target_env = "sim"` cfgs](rust-lang/rust#139451) as replacements for the `target_abi` cfgs with the same values. <a id="1.91.0-Compiler"></a> ## Compiler - [Don't warn on never-to-any `as` casts as unreachable](rust-lang/rust#144804) <a id="1.91.0-Platform-Support"></a> ## Platform Support - [Promote `aarch64-pc-windows-gnullvm` and `x86_64-pc-windows-gnullvm` to Tier 2 with host tools.](rust-lang/rust#143031) Note: llvm-tools and MSI installers are missing but will be added in future releases. - [Promote `aarch64-pc-windows-msvc` to Tier 1](rust-lang/rust#145682) 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 <a id="1.91.0-Libraries"></a> ## Libraries - [Print thread ID in panic message](rust-lang/rust#115746) - [Fix overly restrictive lifetime in `core::panic::Location::file` return type](rust-lang/rust#132087) - [Guarantee parameter order for `_by()` variants of `min` / `max`/ `minmax` in `std::cmp`](rust-lang/rust#139357) - [Document assumptions about `Clone` and `Eq` traits](rust-lang/rust#144330) - [`std::thread`: Return error if setting thread stack size fails](rust-lang/rust#144210) This used to panic within the standard library. <a id="1.91.0-Stabilized-APIs"></a> ## Stabilized APIs - [`Path::file_prefix`](https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.file_prefix) - [`AtomicPtr::fetch_ptr_add`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_ptr_add) - [`AtomicPtr::fetch_ptr_sub`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_ptr_sub) - [`AtomicPtr::fetch_byte_add`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_byte_add) - [`AtomicPtr::fetch_byte_sub`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_byte_sub) - [`AtomicPtr::fetch_or`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_or) - [`AtomicPtr::fetch_and`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_and) - [`AtomicPtr::fetch_xor`](https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_xor) - [`{integer}::strict_add`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_add) - [`{integer}::strict_sub`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_sub) - [`{integer}::strict_mul`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_mul) - [`{integer}::strict_div`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_div) - [`{integer}::strict_div_euclid`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_div_euclid) - [`{integer}::strict_rem`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_rem) - [`{integer}::strict_rem_euclid`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_rem_euclid) - [`{integer}::strict_neg`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_neg) - [`{integer}::strict_shl`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_shl) - [`{integer}::strict_shr`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_shr) - [`{integer}::strict_pow`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_pow) - [`i{N}::strict_add_unsigned`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_add_unsigned) - [`i{N}::strict_sub_unsigned`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_sub_unsigned) - [`i{N}::strict_abs`](https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_abs) - [`u{N}::strict_add_signed`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_add_signed) - [`u{N}::strict_sub_signed`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_sub_signed) - [`PanicHookInfo::payload_as_str`](https://doc.rust-lang.org/stable/std/panic/struct.PanicHookInfo.html#method.payload_as_str) - [`core::iter::chain`](https://doc.rust-lang.org/stable/core/iter/fn.chain.html) - [`u{N}::checked_signed_diff`](https://doc.rust-lang.org/stable/std/primitive.u16.html#method.checked_signed_diff) - [`core::array::repeat`](https://doc.rust-lang.org/stable/core/array/fn.repeat.html) - [`PathBuf::add_extension`](https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.add_extension) - [`PathBuf::with_added_extension`](https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.with_added_extension) - [`Duration::from_mins`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_mins) - [`Duration::from_hours`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_hours) - [`impl PartialEq<str> for PathBuf`](https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-PartialEq%3Cstr%3E-for-PathBuf) - [`impl PartialEq<String> for PathBuf`](https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-PartialEq%3CString%3E-for-PathBuf) - [`impl PartialEq<str> for Path`](https://doc.rust-lang.org/stable/std/path/struct.Path.html#impl-PartialEq%3Cstr%3E-for-Path) - [`impl PartialEq<String> for Path`](https://doc.rust-lang.org/stable/std/path/struct.Path.html#impl-PartialEq%3CString%3E-for-Path) - [`impl PartialEq<PathBuf> for String`](https://doc.rust-lang.org/stable/std/string/struct.String.html#impl-PartialEq%3CPathBuf%3E-for-String) - [`impl PartialEq<Path> for String`](https://doc.rust-lang.org/stable/std/string/struct.String.html#impl-PartialEq%3CPath%3E-for-String) - [`impl PartialEq<PathBuf> for str`](https://doc.rust-lang.org/stable/std/primitive.str.html#impl-PartialEq%3CPathBuf%3E-for-str) - [`impl PartialEq<Path> for str`](https://doc.rust-lang.org/stable/std/primitive.str.html#impl-PartialEq%3CPath%3E-for-str) - [`Ipv4Addr::from_octets`](https://doc.rust-lang.org/stable/std/net/struct.Ipv4Addr.html#method.from_octets) - [`Ipv6Addr::from_octets`](https://doc.rust-lang.org/stable/std/net/struct.Ipv6Addr.html#method.from_octets) - [`Ipv6Addr::from_segments`](https://doc.rust-lang.org/stable/std/net/struct.Ipv6Addr.html#method.from_segments) - [`impl<T> Default for Pin<Box<T>> where Box<T>: Default, T: ?Sized`](https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CBox%3CT%3E%3E) - [`impl<T> Default for Pin<Rc<T>> where Rc<T>: Default, T: ?Sized`](https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CRc%3CT%3E%3E) - [`impl<T> Default for Pin<Arc<T>> where Arc<T>: Default, T: ?Sized`](https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CArc%3CT%3E%3E) - [`Cell::as_array_of_cells`](https://doc.rust-lang.org/stable/std/cell/struct.Cell.html#method.as_array_of_cells) - [`u{N}::carrying_add`](https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_add) - [`u{N}::borrowing_sub`](https://doc.rust-lang.org/stable/std/primitive.u64.html#method.borrowing_sub) - [`u{N}::carrying_mul`](https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_mul) - [`u{N}::carrying_mul_add`](https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_mul_add) - [`BTreeMap::extract_if`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.extract_if) - [`BTreeSet::extract_if`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeSet.html#method.extract_if) - [`impl Debug for windows::ffi::EncodeWide<'_>`](https://doc.rust-lang.org/stable/std/os/windows/ffi/struct.EncodeWide.html#impl-Debug-for-EncodeWide%3C'_%3E) - [`str::ceil_char_boundary`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.ceil_char_boundary) - [`str::floor_char_boundary`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.floor_char_boundary) - [`impl Sum for Saturating<u{N}>`](https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Sum-for-Saturating%3Cu32%3E) - [`impl Sum<&Self> for Saturating<u{N}>`](https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Sum%3C%26Saturating%3Cu32%3E%3E-for-Saturating%3Cu32%3E) - [`impl Product for Saturating<u{N}>`](https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Product-for-Saturating%3Cu32%3E) - [`impl Product<&Self> for Saturating<u{N}>`](https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Product%3C%26Saturating%3Cu32%3E%3E-for-Saturating%3Cu32%3E) These previously stable APIs are now stable in const contexts: - [`<[T; N]>::each_ref`](https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_ref) - [`<[T; N]>::each_mut`](https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_mut) - [`OsString::new`](https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.new) - [`PathBuf::new`](https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.new) - [`TypeId::of`](https://doc.rust-lang.org/stable/std/any/struct.TypeId.html#method.of) - [`ptr::with_exposed_provenance`](https://doc.rust-lang.org/stable/std/ptr/fn.with_exposed_provenance.html) - [`ptr::with_exposed_provenance_mut`](https://doc.rust-lang.org/stable/std/ptr/fn.with_exposed_provenance_mut.html) <a id="1.91.0-Cargo"></a> ## Cargo - 🎉 Stabilize `build.build-dir`. This config sets the directory where intermediate build artifacts are stored. These artifacts are produced by Cargo and rustc during the build process. End users usually won't need to interact with them, and the layout inside `build-dir` is an implementation detail that may change without notice. ([config doc](https://doc.rust-lang.org/stable/cargo/reference/config.html#buildbuild-dir)) ([build cache doc](https://doc.rust-lang.org/stable/cargo/reference/build-cache.html)) [#15833](rust-lang/cargo#15833) [#15840](rust-lang/cargo#15840) - The `--target` flag and the `build.target` configuration can now take literal `"host-tuple"` string, which will internally be substituted by the host machine's target triple. [#15838](rust-lang/cargo#15838) [#16003](rust-lang/cargo#16003) [#16032](rust-lang/cargo#16032) <a id="1.91.0-Rustdoc"></a> ## Rustdoc - [In search results, rank doc aliases lower than non-alias items with the same name](rust-lang/rust#145100) - [Raw pointers now work in type-based search like references](rust-lang/rust#145731). This means you can now search for things like `*const u8 ->`, and additionally functions that take or return raw pointers will now display their signature properly in search results. <a id="1.91.0-Compatibility-Notes"></a> ## Compatibility Notes - [Always require coroutine captures to be drop-live](rust-lang/rust#144156) - [Apple: Always pass SDK root when linking with `cc`, and pass it via `SDKROOT` env var](rust-lang/rust#131477). This should fix linking issues with `rustc` running inside Xcode. Libraries in `/usr/local/lib` may no longer be linked automatically, if you develop or use a crate that relies on this, you should explicitly set `cargo::rustc-link-search=/usr/local/lib` in a `build.rs` script. - [Relaxed bounds in associated type bound position like in `TraitRef<AssocTy: ?Sized>` are now correctly forbidden](rust-lang/rust#135331) - [Add unstable `#[sanitize(xyz = "on|off")]` built-in attribute that shadows procedural macros with the same name](rust-lang/rust#142681) - [Fix the drop checker being more permissive for bindings declared with let-else](rust-lang/rust#143028) - [Be more strict when parsing attributes, erroring on many invalid attributes](rust-lang/rust#144689) - [Error on invalid `#[should_panic]` attributes](rust-lang/rust#143808) - [Error on invalid `#[link]` attributes](rust-lang/rust#143193) - [Mark all deprecation lints in name resolution as deny-by-default and also report in dependencies](rust-lang/rust#143929) - The lint `semicolon_in_expressions_from_macros`, for `macro_rules!` macros in expression position that expand to end in a semicolon (`;`), is now deny-by-default. It was already warn-by-default, and a future compatibility warning (FCW) that warned even in dependencies. This lint will become a hard error in the future. - [Trait impl modifiers (e.g., `unsafe`, `!`, `default`) in inherent impls are no longer syntactically valid](rust-lang/rust#144386) - [Start reporting future breakage for `ill_formed_attribute_input` in dependencies](rust-lang/rust#144544) - [Restrict the scope of temporaries created by the macros `pin!`, `format_args!`, `write!`, and `writeln!` in `if let` scrutinees in Rust Edition 2024.](rust-lang/rust#145342) This applies [Rust Edition 2024's `if let` temporary scope rules](https://doc.rust-lang.org/edition-guide/rust-2024/temporary-if-let-scope.html) to these temporaries, which previously could live past the `if` expression regardless of Edition. - [Invalid numeric literal suffixes in tuple indexing, tuple struct indexing, and struct field name positions are now correctly rejected](rust-lang/rust#145463) - [Closures marked with the keyword `static` are now syntactically invalid](rust-lang/rust#145604) - [Shebangs inside `--cfg` and `--check-cfg` arguments are no longer allowed](rust-lang/rust#146211) - [Add future incompatibility lint for temporary lifetime shortening in Rust 1.92](rust-lang/rust#147056) Cargo compatibility notes: - `cargo publish` no longer keeps `.crate` tarballs as final build artifacts when `build.build-dir` is set. These tarballs were previously included due to an oversight and are now treated as intermediate artifacts. To get `.crate` tarballs as final artifacts, use `cargo package`. In a future version, this change will apply regardless of `build.build-dir`. [#15910](rust-lang/cargo#15910) - Adjust Cargo messages to match rustc diagnostic style. This changes some of the terminal colors used by Cargo messages. [#15928](rust-lang/cargo#15928) - Tools and projects relying on the [internal details of Cargo's `build-dir`](https://doc.rust-lang.org/cargo/reference/build-cache.html) may not work for users changing their `build-dir` layout. For those doing so, we'd recommend proactively testing these cases particularly as we are considering changing the default location of the `build-dir` in the future ([cargo#16147](rust-lang/cargo#16147)). If you can't migrate off of Cargo's internal details, we'd like to learn more about your use case as we prepare to change the layout of the `build-dir` ([cargo#15010](rust-lang/cargo#15010)). <a id="1.91.0-Internal-Changes"></a> ## 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 21](rust-lang/rust#143684) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

Pkgsrc changes: * Adjust patches to adapt to upstream changes and new versions. * assosicated checksums * Add a workaround for LLVM mis-using -isystem. Reported upstream at llvm/llvm-project#166420 Noteable failures at the time of commit: * The cross-build for armv6 fails, reported upstream at rust-lang/rust#148464 * The cross-build for powerpc fails, reported upstream at rust-lang/rust#148497 This is R_PPC_PLTREL24 which now has insufficient range. Asked for recpie for directing the rust code generator to cope. Upstream changes relative to 1.90.0: Version 1.91.0 (2025-10-30) ========================== Language -------- - [Lower pattern bindings in the order they're written and base drop order on primary bindings' order] (rust-lang/rust#143764) - [Stabilize declaration of C-style variadic functions for `sysv64`, `win64`, `efiapi`, and `aapcs` ABIs] (rust-lang/rust#144066). This brings these ABIs in line with the C ABI: variadic functions can be declared in extern blocks but not defined. - [Add `dangling_pointers_from_locals` lint to warn against dangling pointers from local variables] (rust-lang/rust#144322) - [Upgrade `semicolon_in_expressions_from_macros` from warn to deny] (rust-lang/rust#144369) - [Stabilize LoongArch32 inline assembly] (rust-lang/rust#144402) - [Add warn-by-default `integer_to_ptr_transmutes` lint against integer-to-pointer transmutes] (rust-lang/rust#144531) - [Stabilize `sse4a` and `tbm` target features] (rust-lang/rust#144542) - [Add `target_env = "macabi"` and `target_env = "sim"` cfgs] (rust-lang/rust#139451) as replacements for the `target_abi` cfgs with the same values. Compiler -------- - [Don't warn on never-to-any `as` casts as unreachable] (rust-lang/rust#144804) Platform Support ---------------- - [Promote `aarch64-pc-windows-gnullvm` and `x86_64-pc-windows-gnullvm` to Tier 2 with host tools.] (rust-lang/rust#143031) Note: llvm-tools and MSI installers are missing but will be added in future releases. - [Promote `aarch64-pc-windows-msvc` to Tier 1] (rust-lang/rust#145682) 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 --------- - [Print thread ID in panic message] (rust-lang/rust#115746) - [Fix overly restrictive lifetime in `core::panic::Location::file` return type] (rust-lang/rust#132087) - [Guarantee parameter order for `_by()` variants of `min` / `max`/ `minmax` in `std::cmp`] (rust-lang/rust#139357) - [Document assumptions about `Clone` and `Eq` traits] (rust-lang/rust#144330) - [`std::thread`: Return error if setting thread stack size fails] (rust-lang/rust#144210) This used to panic within the standard library. Stabilized APIs --------------- - [`Path::file_prefix`] (https://doc.rust-lang.org/stable/std/path/struct.Path.html#method.file_prefix) - [`AtomicPtr::fetch_ptr_add`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_ptr_add) - [`AtomicPtr::fetch_ptr_sub`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_ptr_sub) - [`AtomicPtr::fetch_byte_add`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_byte_add) - [`AtomicPtr::fetch_byte_sub`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_byte_sub) - [`AtomicPtr::fetch_or`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_or) - [`AtomicPtr::fetch_and`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_and) - [`AtomicPtr::fetch_xor`] (https://doc.rust-lang.org/stable/std/sync/atomic/struct.AtomicPtr.html#method.fetch_xor) - [`{integer}::strict_add`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_add) - [`{integer}::strict_sub`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_sub) - [`{integer}::strict_mul`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_mul) - [`{integer}::strict_div`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_div) - [`{integer}::strict_div_euclid`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_div_euclid) - [`{integer}::strict_rem`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_rem) - [`{integer}::strict_rem_euclid`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_rem_euclid) - [`{integer}::strict_neg`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_neg) - [`{integer}::strict_shl`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_shl) - [`{integer}::strict_shr`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_shr) - [`{integer}::strict_pow`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_pow) - [`i{N}::strict_add_unsigned`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_add_unsigned) - [`i{N}::strict_sub_unsigned`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_sub_unsigned) - [`i{N}::strict_abs`] (https://doc.rust-lang.org/stable/std/primitive.i32.html#method.strict_abs) - [`u{N}::strict_add_signed`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_add_signed) - [`u{N}::strict_sub_signed`] (https://doc.rust-lang.org/stable/std/primitive.u32.html#method.strict_sub_signed) - [`PanicHookInfo::payload_as_str`] (https://doc.rust-lang.org/stable/std/panic/struct.PanicHookInfo.html#method.payload_as_str) - [`core::iter::chain`] (https://doc.rust-lang.org/stable/core/iter/fn.chain.html) - [`u{N}::checked_signed_diff`] (https://doc.rust-lang.org/stable/std/primitive.u16.html#method.checked_signed_diff) - [`core::array::repeat`] (https://doc.rust-lang.org/stable/core/array/fn.repeat.html) - [`PathBuf::add_extension`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.add_extension) - [`PathBuf::with_added_extension`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.with_added_extension) - [`Duration::from_mins`] (https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_mins) - [`Duration::from_hours`] (https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.from_hours) - [`impl PartialEq<str> for PathBuf`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-PartialEq%3Cstr%3E-for-PathBuf) - [`impl PartialEq<String> for PathBuf`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#impl-PartialEq%3CString%3E-for-PathBuf) - [`impl PartialEq<str> for Path`] (https://doc.rust-lang.org/stable/std/path/struct.Path.html#impl-PartialEq%3Cstr%3E-for-Path) - [`impl PartialEq<String> for Path`] (https://doc.rust-lang.org/stable/std/path/struct.Path.html#impl-PartialEq%3CString%3E-for-Path) - [`impl PartialEq<PathBuf> for String`] (https://doc.rust-lang.org/stable/std/string/struct.String.html#impl-PartialEq%3CPathBuf%3E-for-String) - [`impl PartialEq<Path> for String`] (https://doc.rust-lang.org/stable/std/string/struct.String.html#impl-PartialEq%3CPath%3E-for-String) - [`impl PartialEq<PathBuf> for str`] (https://doc.rust-lang.org/stable/std/primitive.str.html#impl-PartialEq%3CPathBuf%3E-for-str) - [`impl PartialEq<Path> for str`] (https://doc.rust-lang.org/stable/std/primitive.str.html#impl-PartialEq%3CPath%3E-for-str) - [`Ipv4Addr::from_octets`] (https://doc.rust-lang.org/stable/std/net/struct.Ipv4Addr.html#method.from_octets) - [`Ipv6Addr::from_octets`] (https://doc.rust-lang.org/stable/std/net/struct.Ipv6Addr.html#method.from_octets) - [`Ipv6Addr::from_segments`] (https://doc.rust-lang.org/stable/std/net/struct.Ipv6Addr.html#method.from_segments) - [`impl<T> Default for Pin<Box<T>> where Box<T>: Default, T: ?Sized`] (https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CBox%3CT%3E%3E) - [`impl<T> Default for Pin<Rc<T>> where Rc<T>: Default, T: ?Sized`] (https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CRc%3CT%3E%3E) - [`impl<T> Default for Pin<Arc<T>> where Arc<T>: Default, T: ?Sized`] (https://doc.rust-lang.org/stable/std/default/trait.Default.html#impl-Default-for-Pin%3CArc%3CT%3E%3E) - [`Cell::as_array_of_cells`] (https://doc.rust-lang.org/stable/std/cell/struct.Cell.html#method.as_array_of_cells) - [`u{N}::carrying_add`] (https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_add) - [`u{N}::borrowing_sub`] (https://doc.rust-lang.org/stable/std/primitive.u64.html#method.borrowing_sub) - [`u{N}::carrying_mul`] (https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_mul) - [`u{N}::carrying_mul_add`] (https://doc.rust-lang.org/stable/std/primitive.u64.html#method.carrying_mul_add) - [`BTreeMap::extract_if`] (https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.extract_if) - [`BTreeSet::extract_if`] (https://doc.rust-lang.org/stable/std/collections/struct.BTreeSet.html#method.extract_if) - [`impl Debug for windows::ffi::EncodeWide<'_>`] (https://doc.rust-lang.org/stable/std/os/windows/ffi/struct.EncodeWide.html#impl-Debug-for-EncodeWide%3C'_%3E) - [`str::ceil_char_boundary`] (https://doc.rust-lang.org/stable/std/primitive.str.html#method.ceil_char_boundary) - [`str::floor_char_boundary`] (https://doc.rust-lang.org/stable/std/primitive.str.html#method.floor_char_boundary) - [`impl Sum for Saturating<u{N}>`] (https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Sum-for-Saturating%3Cu32%3E) - [`impl Sum<&Self> for Saturating<u{N}>`] (https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Sum%3C%26Saturating%3Cu32%3E%3E-for-Saturating%3Cu32%3E) - [`impl Product for Saturating<u{N}>`] (https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Product-for-Saturating%3Cu32%3E) - [`impl Product<&Self> for Saturating<u{N}>`] (https://doc.rust-lang.org/stable/std/num/struct.Saturating.html#impl-Product%3C%26Saturating%3Cu32%3E%3E-for-Saturating%3Cu32%3E) These previously stable APIs are now stable in const contexts: - [`<[T; N]>::each_ref`] (https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_ref) - [`<[T; N]>::each_mut`] (https://doc.rust-lang.org/stable/std/primitive.array.html#method.each_mut) - [`OsString::new`] (https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.new) - [`PathBuf::new`] (https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.new) - [`TypeId::of`] (https://doc.rust-lang.org/stable/std/any/struct.TypeId.html#method.of) - [`ptr::with_exposed_provenance`] (https://doc.rust-lang.org/stable/std/ptr/fn.with_exposed_provenance.html) - [`ptr::with_exposed_provenance_mut`] (https://doc.rust-lang.org/stable/std/ptr/fn.with_exposed_provenance_mut.html) Cargo ----- - 🎉 Stabilize `build.build-dir`. This config sets the directory where intermediate build artifacts are stored. These artifacts are produced by Cargo and rustc during the build process. End users usually won't need to interact with them, and the layout inside `build-dir` is an implementation detail that may change without notice. ([config doc] (https://doc.rust-lang.org/stable/cargo/reference/config.html#buildbuild-dir)) ([build cache doc] (https://doc.rust-lang.org/stable/cargo/reference/build-cache.html)) [#15833](rust-lang/cargo#15833) [#15840](rust-lang/cargo#15840) - The `--target` flag and the `build.target` configuration can now take literal `"host-tuple"` string, which will internally be substituted by the host machine's target triple. [#15838](rust-lang/cargo#15838) [#16003](rust-lang/cargo#16003) [#16032](rust-lang/cargo#16032) Rustdoc ----- - [In search results, rank doc aliases lower than non-alias items with the same name](rust-lang/rust#145100) - [Raw pointers now work in type-based search like references] (rust-lang/rust#145731). This means you can now search for things like `*const u8 ->`, and additionally functions that take or return raw pointers will now display their signature properly in search results. Compatibility Notes ------------------- - [Always require coroutine captures to be drop-live] (rust-lang/rust#144156) - [Apple: Always pass SDK root when linking with `cc`, and pass it via `SDKROOT` env var] (rust-lang/rust#131477). This should fix linking issues with `rustc` running inside Xcode. Libraries in `/usr/local/lib` may no longer be linked automatically, if you develop or use a crate that relies on this, you should explicitly set `cargo::rustc-link-search=/usr/local/lib` in a `build.rs` script. - [Relaxed bounds in associated type bound position like in `TraitRef<AssocTy: ?Sized>` are now correctly forbidden] (rust-lang/rust#135331) - [Add unstable `#[sanitize(xyz = "on|off")]` built-in attribute that shadows procedural macros with the same name] (rust-lang/rust#142681) - [Fix the drop checker being more permissive for bindings declared with let-else] (rust-lang/rust#143028) - [Be more strict when parsing attributes, erroring on many invalid attributes] (rust-lang/rust#144689) - [Error on invalid `#[should_panic]` attributes] (rust-lang/rust#143808) - [Error on invalid `#[link]` attributes] (rust-lang/rust#143193) - [Mark all deprecation lints in name resolution as deny-by-default and also report in dependencies] (rust-lang/rust#143929) - The lint `semicolon_in_expressions_from_macros`, for `macro_rules!` macros in expression position that expand to end in a semicolon (`;`), is now deny-by-default. It was already warn-by-default, and a future compatibility warning (FCW) that warned even in dependencies. This lint will become a hard error in the future. - [Trait impl modifiers (e.g., `unsafe`, `!`, `default`) in inherent impls are no longer syntactically valid] (rust-lang/rust#144386) - [Start reporting future breakage for `ill_formed_attribute_input` in dependencies] (rust-lang/rust#144544) - [Restrict the scope of temporaries created by the macros `pin!`, `format_args!`, `write!`, and `writeln!` in `if let` scrutinees in Rust Edition 2024.] (rust-lang/rust#145342) This applies [Rust Edition 2024's `if let` temporary scope rules] (https://doc.rust-lang.org/edition-guide/rust-2024/temporary-if-let-scope.html) to these temporaries, which previously could live past the `if` expression regardless of Edition. - [Invalid numeric literal suffixes in tuple indexing, tuple struct indexing, and struct field name positions are now correctly rejected] (rust-lang/rust#145463) - [Closures marked with the keyword `static` are now syntactically invalid] (rust-lang/rust#145604) - [Shebangs inside `--cfg` and `--check-cfg` arguments are no longer allowed] (rust-lang/rust#146211) - [Add future incompatibility lint for temporary lifetime shortening in Rust 1.92] (rust-lang/rust#147056) Cargo compatibility notes: - `cargo publish` no longer keeps `.crate` tarballs as final build artifacts when `build.build-dir` is set. These tarballs were previously included due to an oversight and are now treated as intermediate artifacts. To get `.crate` tarballs as final artifacts, use `cargo package`. In a future version, this change will apply regardless of `build.build-dir`. [#15910](rust-lang/cargo#15910) - Adjust Cargo messages to match rustc diagnostic style. This changes some of the terminal colors used by Cargo messages. [#15928](rust-lang/cargo#15928) - Tools and projects relying on the [internal details of Cargo's `build-dir`] (https://doc.rust-lang.org/cargo/reference/build-cache.html) may not work for users changing their `build-dir` layout. For those doing so, we'd recommend proactively testing these cases particularly as we are considering changing the default location of the `build-dir` in the future ([cargo#16147](rust-lang/cargo#16147)). If you can't migrate off of Cargo's internal details, we'd like to learn more about your use case as we prepare to change the layout of the `build-dir` ([cargo#15010] (rust-lang/cargo#15010)). 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 21](rust-lang/rust#143684)

add positive and negative tests for temporary scope shortening FCW

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warn on future errors from temporary lifetimes shortening in Rust 1.92

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add a test for shortening super let binding lifetimes

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warn on shortening super let binding lifetimes

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Draft release notes for 1.91 #147010

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theemathas mentioned this pull request Nov 3, 2025

Borrowed temporary dropped on nightly but works on stable #148427

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		static_assert_size!(Expr<'_>, 72);
		static_assert_size!(Expr<'_>, 80);

	diag.primary_message("temporary lifetime shortening in Rust 1.92");
	diag.primary_message("this temporary's lifetime will be shortened starting in Rust 1.92");

[beta-1.91] Warn on future errors from temporary lifetimes shortening in Rust 1.92 #147056

[beta-1.91] Warn on future errors from temporary lifetimes shortening in Rust 1.92 #147056

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