Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive` by theemathas · Pull Request #158770 · rust-lang/rust

theemathas · 2026-07-04T11:02:11Z

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.

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.

rustbot · 2026-07-04T11:02:16Z

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JohnTitor

👍 @bors r+ rollup

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rust-bors · 2026-07-05T11:14:34Z

📌 Commit b570ebd has been approved by JohnTitor

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 2. This pull request will be tested once the tree is reopened.

JohnTitor · 2026-07-05T11:15:57Z

(not beta-nominated but if the promotion happens meanwhile, please add the label)

…=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.

JonathanBrouwer · 2026-07-05T13:37:45Z

@bors try jobs=test-various

Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive` try-job: test-various

rust-bors · 2026-07-05T14:33:30Z

💔 Test for e35034e failed: CI. Failed job:

try - test-various (web logs, enhanced plaintext logs)

theemathas · 2026-07-05T14:40:14Z

Does catch_unwind not work on wasm?

JonathanBrouwer · 2026-07-05T14:40:43Z

@bors r-

rust-bors · 2026-07-05T14:40:49Z

This pull request was unapproved.

This PR was contained in a rollup (#158806), which was unapproved.

View changes since this unapproval

theemathas · 2026-07-05T15:44:24Z

The test failed because wasm32-wasip1 is compiled with -Cpanic=abort by default. The doctest for catch_unwind itself doesn't fail for a similar reason, because the CI setup for wasm32-wasip1 doesn't run library/std tests, and catch_unwind is in std. The CI for this target, however, runs library/core tests, which includes this PR's test in core.

theemathas · 2026-07-05T16:06:26Z

@bors try

Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive`

rust-bors · 2026-07-05T18:16:39Z

☀️ Try build successful (CI)
Build commit: e293995 (e293995c615d98a73788f901c1dbe514f04a15ec)
Base parent: 4eb6253 (4eb62535fc12dd1a63fd43a4173e224e79313c4d)

theemathas · 2026-07-06T03:46:39Z

This didn't make it in time for 1.98.0, since #158740 has been merged. So, this will need a backport to 1.98.0.

JohnTitor · 2026-07-06T09:32:32Z

@bors r+

rust-bors · 2026-07-06T09:32:36Z

📌 Commit 1920371 has been approved by JohnTitor

It is now in the queue for this repository.

…=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.

…uwer Rollup of 12 pull requests Successful merges: - #156976 (enable eager `param_env` norm in new solver) - #158537 (Add `std::io::cursor::WriteThroughCursor`) - #158540 (Move `std::io::Seek` to `core::io`) - #157820 (consider subtyping when checking if an infer var is sized) - #158505 (Update POSIX edition links) - #158853 (Fix typo for link on nto-qnx.md) - #157466 (Better error message when bare type in impl parameter list) - #157966 (Emit a suggestion to cast the never type into a concrete type when it fails to satisfy an `impl Trait` bound) - #158381 (Expose debug scope of statement and terminator in rustc_public) - #158405 (rustc_target: Add ARMv8-M related target features) - #158770 (Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive`) - #158820 (Fix rustdoc ICE on deprecated note in inlined re-export chain)

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.

rustbot assigned JohnTitor Jul 4, 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 Jul 4, 2026

theemathas mentioned this pull request Jul 4, 2026

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

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JohnTitor approved these changes Jul 5, 2026

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JonathanBrouwer mentioned this pull request Jul 5, 2026

Rollup of 12 pull requests #158806

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Auto merge of #158770 - theemathas:range-inclusive-from, r=<try>

e35034e

Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive` try-job: test-various

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Disable RangeInclusive's From test when unwinding isn't available.

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rust-bors Bot pushed a commit that referenced this pull request Jul 5, 2026

Auto merge of #158770 - theemathas:range-inclusive-from, r=<try>

e293995

Weaken guarantee for `From<legacy::RangeInclusive> for RangeInclusive`

theemathas removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jul 6, 2026

theemathas added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 6, 2026

theemathas added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Jul 6, 2026

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 Jul 6, 2026

This was referenced Jul 6, 2026

Rollup of 12 pull requests #158858

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Rollup of 12 pull requests #158864

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rust-bors Bot merged commit 3ffc2ad into rust-lang:main Jul 6, 2026
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rustbot added this to the 1.99.0 milestone Jul 6, 2026

theemathas deleted the range-inclusive-from branch July 7, 2026 00:28

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