[compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes#158996

scottmcm · 2026-07-09T05:28:05Z

For something unconditionally Ord, this is better than using partial_cmp on fields.

I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

…dexes For something unconditionally `Ord`, this is better than using `partial_cmp` on fields. I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

rustbot · 2026-07-09T05:28:09Z

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folkertdev · 2026-07-09T12:56:09Z

@bors r+ rollup

rust-bors · 2026-07-09T12:56:13Z

📌 Commit 7269b96 has been approved by folkertdev

It is now in the queue for this repository.

…kertdev [compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes For something unconditionally `Ord`, this is better than using `partial_cmp` on fields. I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

Kobzol · 2026-07-09T16:04:17Z

@bors try @rust-timer queue

Just to make sure, spans are quite hot.

[compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes

…uwer Rollup of 21 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158510 (Enable `static_position_independent_executables` on all gnu and musl targets) - #158541 (Move `std::io::Write` to `core::io`) - #158899 (Fix `unaligned_volatile_store` by removing `MemFlags::UNALIGNED`) - #155429 (Support `u128`/`i128` c-variadic arguments) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes) - #159005 (Use `as_lang_item` instead of repeatedly matching)

rust-bors · 2026-07-09T18:10:52Z

☀️ Try build successful (CI)
Build commit: 5e75c18 (5e75c1827c11c6e0f4cf5e862d7febc153bee8aa)
Base parent: 561ea2b (561ea2bfa3022226082e2db39d6ccb241e9e34bc)

…kertdev [compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes For something unconditionally `Ord`, this is better than using `partial_cmp` on fields. I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

rust-timer · 2026-07-09T20:10:04Z

Finished benchmarking commit (5e75c18): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (secondary 6.5%)

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)	6.5%	[6.5%, 6.5%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (primary 0.3%, secondary 0.1%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	2.6%	[2.2%, 2.9%]	4
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-3.2%	[-4.4%, -2.2%]	3
All ❌✅ (primary)	0.3%	[-2.1%, 2.6%]	2

Binary size

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

Bootstrap: 489.147s -> 489.205s (0.01%)
Artifact size: 388.47 MiB -> 388.47 MiB (0.00%)

…uwer Rollup of 24 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158510 (Enable `static_position_independent_executables` on all gnu and musl targets) - #158541 (Move `std::io::Write` to `core::io`) - #158899 (Fix `unaligned_volatile_store` by removing `MemFlags::UNALIGNED`) - #156027 (Consider captured regions for opaque type region liveness.) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #157561 (rustdoc: do not include extra stuff in span) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158384 (Allow BackwardIncompatibleDropHint in polonius legacy) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158877 (borrowck: Keep returned `path` from `best_blame_constraint()` consistent) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158995 (Use REST API in linkchecker script) - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes)

…kertdev [compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes For something unconditionally `Ord`, this is better than using `partial_cmp` on fields. I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

Rollup of 24 pull requests Successful merges: - #150946 (intrinsics: Add a fallback for non-const libm float functions) - #158541 (Move `std::io::Write` to `core::io`) - #156027 (Consider captured regions for opaque type region liveness.) - #156370 (Reject linked dylib EII default overrides) - #156508 (Infer all anonymous lifetimes in assoc consts as `'static`) - #157561 (rustdoc: do not include extra stuff in span) - #158617 (allow mGCA const arguments to fall back to anon consts) - #158645 (Fix splat ICEs and ban it in closures) - #158859 (Improve `-Zls` diagnostic message on `.rs` files) - #158988 (Redo `TokenStreamIter`) - #158347 (Improve generic parameters handling for #[diagnostic::on_const]) - #158384 (Allow BackwardIncompatibleDropHint in polonius legacy) - #158722 (delegation: do not always inherit `ConstArgHasType` predicates) - #158739 (view-types: HIR lowering) - #158877 (borrowck: Keep returned `path` from `best_blame_constraint()` consistent) - #158883 (tests: fix enum-match.rs to handle LLVM 23) - #158886 (Add documentation for the `no_std` attribute) - #158940 (Implement feature `char_to_u32`) - #158951 (Merge three `MaxUniverse`s into one) - #158960 (Fix bootstrap submodule path prefix matching) - #158961 (Reapply "LLVM 23: Run AssignGUIDPass in some places") - #158995 (Use REST API in linkchecker script) - #158996 ([compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes) - #159036 (bootstrap: expand '@argfile' arguments to rustc shim)

Rollup merge of #158996 - scottmcm:better-partial-cmp, r=folkertdev [compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes For something unconditionally `Ord`, this is better than using `partial_cmp` on fields. I couldn't find any other cases in the compiler codebase of this, but it's entirely possible I missed some. Let me know if you can think of any.

JonathanBrouwer · 2026-07-12T07:41:56Z

@rust-timer build 4db5f96

rust-timer · 2026-07-12T14:21:32Z

Finished benchmarking commit (4db5f96): comparison URL.

Overall result: ❌ regressions - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.2%	[0.0%, 0.3%]	11
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -3.6%, secondary -3.4%)

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)	-	-	0
Improvements ✅ (primary)	-3.6%	[-3.6%, -3.6%]	1
Improvements ✅ (secondary)	-3.4%	[-7.3%, -1.4%]	4
All ❌✅ (primary)	-3.6%	[-3.6%, -3.6%]	1

Cycles

Results (secondary -0.7%)

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)	4.7%	[2.4%, 8.8%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.4%	[-8.9%, -1.4%]	8
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 490.768s -> 489.353s (-0.29%)
Artifact size: 389.74 MiB -> 389.20 MiB (-0.14%)

JonathanBrouwer · 2026-07-12T20:07:28Z

@rustbot label: +perf-regression-triaged
Noise

rustbot assigned folkertdev Jul 9, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 9, 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 9, 2026

JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 18 pull requests #159013

Closed

JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 21 pull requests #159020

Closed

JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 21 pull requests #159024

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 9, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 9, 2026

Auto merge of #158996 - scottmcm:better-partial-cmp, r=<try>

5e75c18

[compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes

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JonathanBrouwer mentioned this pull request Jul 9, 2026

Rollup of 24 pull requests #159037

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 9, 2026

jhpratt mentioned this pull request Jul 9, 2026

Rollup of 25 pull requests #159045

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jhpratt mentioned this pull request Jul 10, 2026

Rollup of 24 pull requests #159046

Merged

rust-bors Bot merged commit adf4488 into rust-lang:main Jul 10, 2026
14 checks passed

scottmcm deleted the better-partial-cmp branch July 10, 2026 06:50

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rustbot added the perf-regression Performance regression. label Jul 12, 2026

rustbot added the perf-regression-triaged The performance regression has been triaged. label Jul 12, 2026

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[compiler] Implement `PartialOrd` via `Ord` for `Span` and newtype_indexes#158996