Document panic in `RangeInclusive::from(legacy::RangeInclusive)` by tbu- · Pull Request #155421 · rust-lang/rust

tbu- · 2026-04-17T07:51:47Z

rustbot · 2026-04-17T07:51:53Z

rustbot has assigned @jhpratt.
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: @scottmcm, libs
@scottmcm, libs expanded to 7 candidates
Random selection from Mark-Simulacrum, jhpratt, scottmcm

jhpratt · 2026-04-17T07:54:48Z

Has this been approved by T-libs-api? The panic message clearly says unspecified, so adding this documentation would overrule that.

tbu- · 2026-04-17T08:05:02Z

If T-libs doesn't want to guarantee this, I can change the wording to "currently panics, may not panic in the future". Or even "may panic".

fmease · 2026-04-17T08:39:56Z

#155394

Amanieu · 2026-04-27T23:08:23Z

ping @tbu-, CI is failing. You need to add #![feature(new_range_api_legacy)] to the doc tests or import the old range types from core::ops instead.

tbu- · 2026-04-28T15:09:08Z

Thanks for the ping, @Amanieu. I somehow forgot about this PR.

theemathas · 2026-04-29T05:32:13Z

Note: The current status of the PR adds a new stable guarantee that the conversion will panic for an exhausted iterator.

jhpratt · 2026-05-30T17:04:26Z

Nominating given the implicit stability guarantee.

joshtriplett · 2026-06-02T15:17:41Z

@rfcbot merge libs-api

rust-rfcbot · 2026-06-02T15:17:44Z

@joshtriplett 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.

jhpratt · 2026-06-21T09:45:36Z

@bors r-

@bors delegate+

rust-bors · 2026-06-21T09:45:40Z

This pull request was unapproved.

View changes since this unapproval

rust-bors · 2026-06-21T09:45:41Z

✌️ @tbu-, you can now approve this pull request!

If @jhpratt told you to "r=me" after making some further change, then please make that change and post @bors r=jhpratt.

View changes since this delegation.

tbu- · 2026-06-21T10:01:10Z

@bors r=jhpratt

rust-bors · 2026-06-21T10:01:13Z

📌 Commit 48d2671 has been approved by jhpratt

It is now in the queue for this repository.

rust-log-analyzer · 2026-06-21T10:12:33Z

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)

  IMAGE: x86_64-gnu-miri
##[endgroup]
    Updating crates.io index
error: failed to get `simd-adler32` as a dependency of package `miniz_oxide v0.8.8`
    ... which satisfies dependency `miniz_oxide = "^0.8.5"` of package `flate2 v1.1.9`
    ... which satisfies dependency `flate2 = "^1.1.9"` of package `citool v0.1.0 (/home/runner/work/rust/rust/src/ci/citool)`

Caused by:
  failed to load source for dependency `simd-adler32`

Caused by:

theemathas · 2026-06-21T10:27:50Z

@bors retry

rust-bors · 2026-06-21T10:27:52Z

❗ You can only retry pull requests that are approved and have a previously failed auto build.

Hint: There is currently a pending auto build on this PR. To cancel it, run @bors cancel.

rust-bors · 2026-06-21T13:10:57Z

☀️ Test successful - CI
Approved by: jhpratt
Duration: 3h 9m 28s
Pushing 40f92b3 to main...

github-actions · 2026-06-21T13:14:13Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing a774017 (parent) -> 40f92b3 (this PR)

Test differences

Show 32 test diffs

32 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 40f92b37c4f7566de7348cec4d4c2a350da598d5 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

i686-gnu-nopt-2: 2h 18m -> 1h 26m (-37.6%)
x86_64-msvc-ext1: 2h 11m -> 1h 23m (-36.9%)
x86_64-gnu-llvm-21-2: 1h 33m -> 1h (-35.0%)
dist-i686-mingw: 2h 1m -> 2h 37m (+30.3%)
x86_64-gnu-gcc: 1h 5m -> 47m 6s (-28.4%)
dist-arm-linux-musl: 1h 19m -> 1h 37m (+23.2%)
dist-i686-linux: 1h 46m -> 1h 28m (-16.6%)
dist-android: 24m 1s -> 27m 57s (+16.4%)
aarch64-apple-macos-26: 2h 25m -> 2h 45m (+14.1%)
dist-apple-various: 1h 46m -> 1h 59m (+11.5%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2026-06-21T13:59:07Z

Finished benchmarking commit (40f92b3): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (primary -4.0%, secondary 2.6%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.6%	[2.6%, 2.6%]	1
Improvements ✅ (primary)	-4.0%	[-5.9%, -2.0%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-4.0%	[-5.9%, -2.0%]	2

Cycles

Results (secondary 0.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.5%	[2.3%, 2.8%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 482.353s -> 479.892s (-0.51%)
Artifact size: 390.76 MiB -> 390.75 MiB (-0.00%)

…=JohnTitor Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive` As per rust-lang#155114 (comment), this `From` impl no longer guarantees panicking for exhausted iterators. Instead, it only guarantees that the conversion will either panic or produce an empty range. This is done so that we can optimize the implementation of `legacy::RangeInclusive` in a way such that we cannot check if it has been exhausted in a generic context without a `Step` and/or `PartialOrd` bound. If this PR and/or rust-lang#155114 merges after the 1.98.0 beta branch promotion from the main branch, then this will need a beta backport, since this PR changes the stable guarantee previously made in rust-lang#155421. This PR conflicts with and/or blocks rust-lang#155114.

Rollup merge of #158770 - theemathas:range-inclusive-from, r=JohnTitor Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive` As per #155114 (comment), this `From` impl no longer guarantees panicking for exhausted iterators. Instead, it only guarantees that the conversion will either panic or produce an empty range. This is done so that we can optimize the implementation of `legacy::RangeInclusive` in a way such that we cannot check if it has been exhausted in a generic context without a `Step` and/or `PartialOrd` bound. If this PR and/or #155114 merges after the 1.98.0 beta branch promotion from the main branch, then this will need a beta backport, since this PR changes the stable guarantee previously made in #155421. This PR conflicts with and/or blocks #155114.

This MR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [rust](https://github.com/rust-lang/rust) | tools | minor | `1.97.1` → `1.98.0` | 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> ### [`v1.98.0`](https://github.com/rust-lang/rust/blob/HEAD/RELEASES.md#Version-1980-2026-08-20) [Compare Source](rust-lang/rust@1.97.1...1.98.0) \========================== <a id="1.98.0-Language"></a> ## Language - [Allow shortening lifetime of `&mut` when unsize-coercing, even in an invariant position.](rust-lang/rust#149219) For example, you can now coerce a `Cell<&'long mut i32>` to a `Cell<&'short mut dyn Send>`. Such shortenings were already previously allowed when coercing a `&mut` to a `&`, or coercing a `&` to a `&`. - [Add deny-by-default `invalid_runtime_symbol_definitions` lint and warn-by-default `suspicious_runtime_symbol_definitions` lint](rust-lang/rust#155521) - The lints currently specifically targets `core` runtime symbols like `memcmp`, `memset`, `strlen`, ... and is planned to be expanded in the next few releases. - [Add warn-by-default `c_void_returns` lint to check `core::ffi::c_void` as a return type](rust-lang/rust#156379) <a id="1.98.0-Platform-Support"></a> ## Platform Support - [Add `powerpc64-unknown-linux-gnuelfv2` as Tier 3](rust-lang/rust#144220) - [Add `aarch64-unknown-linux-pauthtest` as Tier 3 target](rust-lang/rust#155722) - [Promote `thumbv7a-none-eabi` to Tier 2](rust-lang/rust#155763) - [Promote `thumbv7a-none-eabihf` to Tier 2](rust-lang/rust#155763) - [Promote `thumbv7r-none-eabi` to Tier 2](rust-lang/rust#155763) - [Promote `thumbv7r-none-eabihf` to Tier 2](rust-lang/rust#155763) - [Promote `thumbv8r-none-eabihf` to Tier 2](rust-lang/rust#155763) 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="1.98.0-Libraries"></a> ## Libraries - [Change `Location<'_>` lifetime to `'static` in `Panic[Hook]Info`](rust-lang/rust#146561) - [Document panic in `RangeInclusive::from(legacy::RangeInclusive)`](rust-lang/rust#155421) - [Document that `ManuallyDrop`'s `Box` interaction has been fixed](rust-lang/rust#155750) - [Stabilize LoongArch CRC Intrinsics](rust-lang/rust#156908) - [The `derive` macro is available at `{core,std}::derive`.](rust-lang/rust#154645) This was previously [unintentionally stabilized in 1.96](rust-lang/rust#159856), but is now [explicitly accepted](rust-lang/rust#154645) as a stabilized API. - Please note that the MSRV for `{core,std}::derive` will be 1.96, and not 1.98. <a id="1.98.0-Stabilized-APIs"></a> ## Stabilized APIs - [`str::substr_range`](https://doc.rust-lang.org/stable/std/primitive.str.html#method.substr_range) - [`[T]::subslice_range`](https://doc.rust-lang.org/stable/std/primitive.slice.html#method.subslice_range) - [`core::fmt::NumBuffer`](https://doc.rust-lang.org/stable/core/fmt/struct.NumBuffer.html) - [`<{integer}>::format_into`](https://doc.rust-lang.org/stable/core/primitive.usize.html#method.format_into) - [`Send/Sync for std::process::CommandArgs`](https://doc.rust-lang.org/stable/std/process/struct.CommandArgs.html#impl-Send-for-CommandArgs%3C'a%3E) - [`{fN}::algebraic_add`](https://doc.rust-lang.org/stable/core/primitive.f32.html#method.algebraic_add) - [`{fN}::algebraic_sub`](https://doc.rust-lang.org/stable/core/primitive.f32.html#method.algebraic_sub) - [`{fN}::algebraic_mul`](https://doc.rust-lang.org/stable/core/primitive.f32.html#method.algebraic_mul) - [`{fN}::algebraic_div`](https://doc.rust-lang.org/stable/core/primitive.f32.html#method.algebraic_div) - [`{fN}::algebraic_rem`](https://doc.rust-lang.org/stable/core/primitive.f32.html#method.algebraic_rem) - [`NonZero<{integer}>::from_str_radix`](https://doc.rust-lang.org/stable/core/num/struct.NonZero.html#method.from_str_radix-4) - [`String::from_utf16le`](https://doc.rust-lang.org/stable/std/string/struct.String.html#method.from_utf16le) - [`String::from_utf16le_lossy`](https://doc.rust-lang.org/stable/std/string/struct.String.html#method.from_utf16le_lossy) - [`String::from_utf16be`](https://doc.rust-lang.org/stable/std/string/struct.String.html#method.from_utf16be) - [`String::from_utf16be_lossy`](https://doc.rust-lang.org/stable/std/string/struct.String.html#method.from_utf16be_lossy) - [`[T]::strip_circumfix`](https://doc.rust-lang.org/stable/core/primitive.slice.html#method.strip_circumfix) - [`str::strip_circumfix`](https://doc.rust-lang.org/stable/core/primitive.str.html#method.strip_circumfix) - [`Atomic<T>::from_mut`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.Atomic.html#method.from_mut) - [`Atomic<T>::get_mut_slice`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.Atomic.html#method.get_mut_slice) - [`Atomic<T>::from_mut_slice`](https://doc.rust-lang.org/stable/core/sync/atomic/struct.Atomic.html#method.from_mut_slice) - [`std::range::legacy`](https://doc.rust-lang.org/stable/std/range/legacy/index.html) <a id="1.98.0-Compatibility-Notes"></a> ## Compatibility Notes - [If fully elided, lifetime bounds of trait object types may now resolve differently or even get rejected in very specific niche scenarios](rust-lang/rust#129543) - [Error in more cases of ambiguous imports](rust-lang/rust#145108) - [Switch the destructors implementation for thread locals on Windows to use Fiber Local Storage (FLS)](rust-lang/rust#148799) - [Convert some cases of the `ambiguous_glob_imports` lint into a hard error](rust-lang/rust#149195) - [Where-bounds of the form `Type = Type` and `Type == Type` are no longer syntactically allowed](rust-lang/rust#153513) - [Ensure Send/Sync is not implemented for std::env::Vars{,Os}](rust-lang/rust#155153) - [Fix that in some attributes, arguments were not properly rejected](rust-lang/rust#155193) - [`repr(transparent)` is now more strict about which fields have "trivial" layout and hence can be ignored: `repr(C)` types, types with private fields, and `#[non_exhaustive]` types are no longer considered "trivial"](rust-lang/rust#155299) - [Correctly check whether types have equal size in `transmute()` when some `repr` attributes are involved.](rust-lang/rust#155418) - [More characters are escaped when printing strings and chars](rust-lang/rust#155527) - [Implement fast path for `derive(PartialOrd)` when deriving `Ord`](rust-lang/rust#155598) This can break crates in practice where a type's PartialOrd and Ord impls were inconsistent with each other. - [Add temporary scope to `assert_eq` and `assert_ne`](rust-lang/rust#155739) - Closed a hole in the pattern matching [structural equality](https://doc.rust-lang.org/reference/patterns.html#constant-patterns) check, preventing cases where a match of a constant would be allowed, despite disagreeing with a manually written `PartialEq` implementation, when a `derive(PartialEq)` implementation for that type also exists. - [On Emscripten the WASM exception handling ABI is now unconditionally used](rust-lang/rust#156928) The `-Zemscripten-wasm-eh=false` flag to switch back to JS exceptions has been removed. - [The UNSAFE\_CODE lint is now consistently emitted for all unsafe attributes](rust-lang/rust#157201) - [Solaris: remove `File::lock` implementation, it has the wrong semantics (return "unsupported" instead)](rust-lang/rust#157509) - [Windows-gnu targets now specify baseline tools versions](rust-lang/rust#158020) - [rustfmt now discovers module files that are defined in `cfg_select!`](rust-lang/rust#158372) This may cause more code to be formatted which was previously ignored. </details> --- ### Configuration 📅 **Schedule**: (UTC) - 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 [Mend Renovate](https://github.com/renovatebot/renovate).

rustbot assigned jhpratt Apr 17, 2026

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. labels Apr 17, 2026

This comment has been minimized.

Sign in to view

tbu- force-pushed the pr_rangeinclusive_from_panic branch from 766773c to f43e3e7 Compare April 17, 2026 08:35

tbu- mentioned this pull request Apr 17, 2026

Document panic behavior of RangeInclusive's From impl #155394

Closed

This comment has been minimized.

Sign in to view

tbu- force-pushed the pr_rangeinclusive_from_panic branch from f43e3e7 to 73b9155 Compare April 28, 2026 13:53

This comment has been minimized.

Sign in to view

tbu- force-pushed the pr_rangeinclusive_from_panic branch from 73b9155 to 70df721 Compare April 28, 2026 15:08

This comment has been minimized.

Sign in to view

tbu- force-pushed the pr_rangeinclusive_from_panic branch from 70df721 to 6502d57 Compare April 28, 2026 19:50

This comment has been minimized.

Sign in to view

tbu- force-pushed the pr_rangeinclusive_from_panic branch from 6502d57 to 5a00cc6 Compare April 28, 2026 21:14

jhpratt added the I-libs-api-nominated [DEPRECATED; DO NOT USE] label May 30, 2026

jhpratt added S-waiting-on-t-libs-api [DEPRECATED; DO NOT USE] and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 30, 2026

This comment has been minimized.

Sign in to view

joshtriplett added the T-libs-api [DEPRECATED; DO NOT USE] label Jun 2, 2026

rust-rfcbot added the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Jun 2, 2026

rust-bors Bot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 21, 2026

Document panic in RangeInclusive::from(legacy::RangeInclusive)

48d2671

tbu- force-pushed the pr_rangeinclusive_from_panic branch from 4ff75dc to 48d2671 Compare June 21, 2026 10:00

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 21, 2026

This comment has been minimized.

Sign in to view

rust-bors Bot added merged-by-bors This PR was explicitly merged by bors. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 21, 2026

rust-bors Bot merged commit 40f92b3 into rust-lang:main Jun 21, 2026
3 of 14 checks passed

rustbot added this to the 1.98.0 milestone Jun 21, 2026

This was referenced Jun 29, 2026

Add Step::forward/backward_overflowing to enable RangeInclusive loop optimizations #155114

Merged

Weaken guarantee for From<legacy::RangeInclusive> for RangeInclusive #158770

Merged

BoxyUwU mentioned this pull request Aug 7, 2026

Draft release notes for 1.98.0 #160700

Closed

Uh oh!

Uh oh!

Conversation

tbu- commented Apr 17, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Apr 17, 2026

Uh oh!

jhpratt commented Apr 17, 2026

Uh oh!

tbu- commented Apr 17, 2026

Uh oh!

This comment has been minimized.

fmease commented Apr 17, 2026

Uh oh!

This comment has been minimized.

Amanieu commented Apr 27, 2026

Uh oh!

This comment has been minimized.

tbu- commented Apr 28, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

theemathas commented Apr 29, 2026

Uh oh!

jhpratt commented May 30, 2026

Uh oh!

This comment has been minimized.

joshtriplett commented Jun 2, 2026

Uh oh!

rust-rfcbot commented Jun 2, 2026 • edited by dtolnay Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

jhpratt commented Jun 21, 2026

Uh oh!

rust-bors Bot commented Jun 21, 2026

Uh oh!

rust-bors Bot commented Jun 21, 2026

Uh oh!

tbu- commented Jun 21, 2026

Uh oh!

rust-bors Bot commented Jun 21, 2026

Uh oh!

This comment has been minimized.

rust-log-analyzer commented Jun 21, 2026

Uh oh!

theemathas commented Jun 21, 2026

Uh oh!

rust-bors Bot commented Jun 21, 2026

Uh oh!

rust-bors Bot commented Jun 21, 2026

Uh oh!

Uh oh!

github-actions Bot commented Jun 21, 2026

Test differences

Job duration changes

Uh oh!

rust-timer commented Jun 21, 2026

Overall result: no relevant changes - no action needed

Instruction count

Max RSS (memory usage)

Cycles

Binary size

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

11 participants

tbu- commented Apr 17, 2026 •

edited by rustbot

Loading

rust-rfcbot commented Jun 2, 2026 •

edited by dtolnay

Loading