Match usize/isize exhaustively with half-open ranges #116692

Nadrieril · 2023-10-13T12:19:45Z

The long-awaited finale to the saga of exhaustiveness checking for integers!

match 0usize {
    0.. => {} // exhaustive!
}
match 0usize {
    0..usize::MAX => {} // helpful error message!
}

Features:

Half-open ranges behave as expected for usize/isize;
Trying to use 0..usize::MAX will tell you that usize::MAX.. is missing and explain why. No more unhelpful "_ is missing";
Everything else stays the same.

This should unblock #37854.

Review-wise:

I recommend looking commit-by-commit;
This regresses perf because of the added complexity in IntRange; hopefully not too much;
I measured each #[inline], they all help a bit with the perf regression (tho I don't get why);
I did not touch MIR building; I expect there's an easy PR there that would skip unnecessary comparisons when the range is half-open.

rustbot · 2023-10-13T12:19:53Z

r? @compiler-errors

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Nadrieril · 2023-10-13T12:20:09Z

@bors try @rust-timer queue

bors · 2023-10-13T12:21:20Z

⌛ Trying commit 6cd0d45 with merge 36d4397...

Match usize/isize exhaustively with half-open ranges The long-awaited finale to the saga of [exhaustiveness checking for integers](rust-lang#50912)! ```rust match 0usize { 0.. => {} // exhaustive! } match 0usize { 0..usize::MAX => {} // helpful error message! } ``` Features: - Half-open ranges behave as expected for `usize`/`isize`; - Trying to use `0..usize::MAX` will tell you that `usize::MAX..` is missing and explain why. No more unhelpful "`_` is missing"; - Everything else stays the same. This should unblock rust-lang#37854. Review-wise: - I recommend looking commit-by-commit; - This regresses perf because of the added complexity in `IntRange`; hopefully not too much; - I measured each `#[inline]`, they all help a bit with the perf regression (tho I don't get why); - I did not touch MIR building; I expect there's an easy PR there that would skip unnecessary comparisons when the range is half-open.

Nadrieril · 2023-10-13T14:30:08Z

@bors try @rust-timer queue

bors · 2023-10-13T14:31:18Z

⌛ Trying commit c0b2138 with merge a23767c...

Match usize/isize exhaustively with half-open ranges The long-awaited finale to the saga of [exhaustiveness checking for integers](rust-lang#50912)! ```rust match 0usize { 0.. => {} // exhaustive! } match 0usize { 0..usize::MAX => {} // helpful error message! } ``` Features: - Half-open ranges behave as expected for `usize`/`isize`; - Trying to use `0..usize::MAX` will tell you that `usize::MAX..` is missing and explain why. No more unhelpful "`_` is missing"; - Everything else stays the same. This should unblock rust-lang#37854. Review-wise: - I recommend looking commit-by-commit; - This regresses perf because of the added complexity in `IntRange`; hopefully not too much; - I measured each `#[inline]`, they all help a bit with the perf regression (tho I don't get why); - I did not touch MIR building; I expect there's an easy PR there that would skip unnecessary comparisons when the range is half-open.

bors · 2023-10-13T15:43:56Z

☀️ Try build successful - checks-actions
Build commit: a23767c (a23767c7a2d14f82db2a6901fbc8e948cb39b0f5)

bors · 2023-10-13T15:43:56Z

☀️ Try build successful - checks-actions
Build commit: a23767c (a23767c7a2d14f82db2a6901fbc8e948cb39b0f5)

rust-timer · 2023-10-13T20:05:55Z

Finished benchmarking commit (a23767c): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.1%	[1.1%, 1.2%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.4%	[-1.5%, -1.3%]	6
All ❌✅ (primary)	1.1%	[1.1%, 1.2%]	2

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 626.271s -> 628.214s (0.31%)
Artifact size: 271.31 MiB -> 271.33 MiB (0.00%)

workingjubilee

yo this is great!

Nadrieril · 2023-10-15T03:27:55Z

Fixed the conflict with master

compiler/rustc_middle/src/thir.rs

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

Nadrieril · 2023-10-21T16:27:02Z

I'm thinking: diagnostic-wise, we currently tend to suggest things like "10..=u32::MAX missing". We could instead suggest 10.. to make half-open range patterns more discoverable

cjgillot · 2023-10-31T18:30:54Z

@bors r+

bors · 2023-10-31T18:30:56Z

📌 Commit 35fe75d has been approved by cjgillot

It is now in the queue for this repository.

Nadrieril · 2023-10-31T19:27:58Z

Thanks for the review!

bors · 2023-11-01T03:17:22Z

⌛ Testing commit 35fe75d with merge 7fc6365...

bors · 2023-11-01T05:22:27Z

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 7fc6365 to master...

rust-timer · 2023-11-01T06:43:30Z

Finished benchmarking commit (7fc6365): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.2%	[1.1%, 1.2%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.2%	[1.1%, 1.2%]	2

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.1%	[1.1%, 1.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-4.2%, -2.8%]	2
All ❌✅ (primary)	1.1%	[1.1%, 1.1%]	1

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.2%	[-3.7%, -2.6%]	4
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 636.96s -> 639.311s (0.37%)
Artifact size: 304.45 MiB -> 304.48 MiB (0.01%)

Nadrieril · 2023-12-04T10:48:55Z

Is this worthy of relnotes? I think this is worthy of relnotes. I'm doing it, someone stop me if I shouldn't

…ize_matching, r=davidtwco Remove the `precise_pointer_size_matching` feature gate `usize` and `isize` are special for pattern matching because their range might depend on the platform. To make code portable across platforms, the following is never considered exhaustive: ```rust let x: usize = ...; match x { 0..=18446744073709551615 => {} } ``` Because of how rust handles constants, this also unfortunately counts `0..=usize::MAX` as non-exhaustive. The [`precise_pointer_size_matching`](rust-lang#56354) feature gate was introduced both for this convenience and for the possibility that the lang team could decide to allow the above. Since then, [half-open range patterns](rust-lang#67264) have been implemented, and since rust-lang#116692 they correctly support `usize`/`isize`: ```rust match 0usize { // exhaustive! 0..5 => {} 5.. => {} } ``` I believe this subsumes all the use cases of the feature gate. Moreover no attempt has been made to stabilize it in the 5 years of its existence. I therefore propose we retire this feature gate. Closes rust-lang#56354

Rollup merge of rust-lang#118598 - Nadrieril:remove_precise_pointer_size_matching, r=davidtwco Remove the `precise_pointer_size_matching` feature gate `usize` and `isize` are special for pattern matching because their range might depend on the platform. To make code portable across platforms, the following is never considered exhaustive: ```rust let x: usize = ...; match x { 0..=18446744073709551615 => {} } ``` Because of how rust handles constants, this also unfortunately counts `0..=usize::MAX` as non-exhaustive. The [`precise_pointer_size_matching`](rust-lang#56354) feature gate was introduced both for this convenience and for the possibility that the lang team could decide to allow the above. Since then, [half-open range patterns](rust-lang#67264) have been implemented, and since rust-lang#116692 they correctly support `usize`/`isize`: ```rust match 0usize { // exhaustive! 0..5 => {} 5.. => {} } ``` I believe this subsumes all the use cases of the feature gate. Moreover no attempt has been made to stabilize it in the 5 years of its existence. I therefore propose we retire this feature gate. Closes rust-lang#56354

Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * For an external LLVM, set dependency of llvm >= 16, in accordance with the upstream changes. * Mark that on NetBSD we now need >= 9.0, so 8.x is no longer supported. * On NetBSD/sparc64 10.x, we now need GCC 12 to build the embedded LLVM, which is version 17; apparently GCC 10.4 or 10.5 mis-compiles it, resulting in an illegal instruction fault during the build. Ref. rust-lang/rust#117231 Upstream changes: Version 1.75.0 (2023-12-28) ========================== - [Stabilize `async fn` and return-position `impl Trait` in traits.] (rust-lang/rust#115822) - [Allow function pointer signatures containing `&mut T` in `const` contexts.] (rust-lang/rust#116015) - [Match `usize`/`isize` exhaustively with half-open ranges.] (rust-lang/rust#116692) - [Guarantee that `char` has the same size and alignment as `u32`.] (rust-lang/rust#116894) - [Document that the null pointer has the 0 address.] (rust-lang/rust#116988) - [Allow partially moved values in `match`.] (rust-lang/rust#103208) - [Add notes about non-compliant FP behavior on 32bit x86 targets.] (rust-lang/rust#113053) - [Stabilize ratified RISC-V target features.] (rust-lang/rust#116485) Compiler -------- - [Rework negative coherence to properly consider impls that only partly overlap.] (rust-lang/rust#112875) - [Bump `COINDUCTIVE_OVERLAP_IN_COHERENCE` to deny, and warn in dependencies.] (rust-lang/rust#116493) - [Consider alias bounds when computing liveness in NLL.] (rust-lang/rust#116733) - [Add the V (vector) extension to the `riscv64-linux-android` target spec.] (rust-lang/rust#116618) - [Automatically enable cross-crate inlining for small functions] (rust-lang/rust#116505) - Add several new tier 3 targets: - [`csky-unknown-linux-gnuabiv2hf`] (rust-lang/rust#117049) - [`i586-unknown-netbsd`] (rust-lang/rust#117170) - [`mipsel-unknown-netbsd`] (rust-lang/rust#117356) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Override `Waker::clone_from` to avoid cloning `Waker`s unnecessarily.] (rust-lang/rust#96979) - [Implement `BufRead` for `VecDeque<u8>`.] (rust-lang/rust#110604) - [Implement `FusedIterator` for `DecodeUtf16` when the inner iterator does.] (rust-lang/rust#110729) - [Implement `Not, Bit{And,Or}{,Assign}` for IP addresses.] (rust-lang/rust#113747) - [Implement `Default` for `ExitCode`.] (rust-lang/rust#114589) - [Guarantee representation of None in NPO] (rust-lang/rust#115333) - [Document when atomic loads are guaranteed read-only.] (rust-lang/rust#115577) - [Broaden the consequences of recursive TLS initialization.] (rust-lang/rust#116172) - [Windows: Support sub-millisecond sleep.] (rust-lang/rust#116461) - [Fix generic bound of `str::SplitInclusive`'s `DoubleEndedIterator` impl] (rust-lang/rust#100806) - [Fix exit status / wait status on non-Unix `cfg(unix)` platforms.] (rust-lang/rust#115108) Stabilized APIs --------------- - [`Atomic*::from_ptr`] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.from_ptr) - [`FileTimes`] (https://doc.rust-lang.org/stable/std/fs/struct.FileTimes.html) - [`FileTimesExt`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTimesExt.html) - [`File::set_modified`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_modified) - [`File::set_times`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_times) - [`IpAddr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/enum.IpAddr.html#method.to_canonical) - [`Ipv6Addr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_canonical) - [`Option::as_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_slice) - [`Option::as_mut_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_mut_slice) - [`pointer::byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_add) - [`pointer::byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset) - [`pointer::byte_offset_from`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset_from) - [`pointer::byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_sub) - [`pointer::wrapping_byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_add) - [`pointer::wrapping_byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_offset) - [`pointer::wrapping_byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_sub) These APIs are now stable in const contexts: - [`Ipv6Addr::to_ipv4_mapped`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_ipv4_mapped) - [`MaybeUninit::assume_init_read`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.assume_init_read) - [`MaybeUninit::zeroed`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.zeroed) - [`mem::discriminant`] (https://doc.rust-lang.org/stable/core/mem/fn.discriminant.html) - [`mem::zeroed`] (https://doc.rust-lang.org/stable/core/mem/fn.zeroed.html) Cargo ----- - [Add new packages to `[workspace.members]` automatically.] (rust-lang/cargo#12779) - [Allow version-less `Cargo.toml` manifests.] (rust-lang/cargo#12786) - [Make browser links out of HTML file paths.] (rust-lang/cargo#12889) Rustdoc ------- - [Accept less invalid Rust in rustdoc.] (rust-lang/rust#117450) - [Document lack of object safety on affected traits.] (rust-lang/rust#113241) - [Hide `#[repr(transparent)]` if it isn't part of the public ABI.] (rust-lang/rust#115439) - [Show enum discriminant if it is a C-like variant.] (rust-lang/rust#116142) Compatibility Notes ------------------- - [FreeBSD targets now require at least version 12.] (rust-lang/rust#114521) - [Formally demote tier 2 MIPS targets to tier 3.] (rust-lang/rust#115238) - [Make misalignment a hard error in `const` contexts.] (rust-lang/rust#115524) - [Fix detecting references to packed unsized fields.] (rust-lang/rust#115583) - [Remove support for compiler plugins.] (rust-lang/rust#116412)

rustbot assigned compiler-errors Oct 13, 2023

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 Oct 13, 2023

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Nadrieril force-pushed the half-open-ranges branch from 6cd0d45 to c0b2138 Compare October 13, 2023 13:20

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workingjubilee approved these changes Oct 15, 2023

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Nadrieril force-pushed the half-open-ranges branch from c0b2138 to 2e766c0 Compare October 15, 2023 03:27

cjgillot reviewed Oct 15, 2023

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Nadrieril removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Oct 17, 2023

cjgillot self-assigned this Oct 19, 2023

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Nadrieril force-pushed the half-open-ranges branch from 167822c to 0d0da35 Compare October 21, 2023 01:22

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Nadrieril force-pushed the half-open-ranges branch from 0d0da35 to 57cc6aa Compare October 21, 2023 15:39

Nadrieril added 3 commits October 27, 2023 19:56

Match usize/isize exhaustively

a4875ae

s/to_pat/to_diagnostic_pat/

feb769a

Make IntRange exclusive

35fe75d

Nadrieril force-pushed the half-open-ranges branch from 3ea92c0 to 35fe75d Compare October 27, 2023 17:58

bors 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 Oct 31, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Nov 1, 2023

bors merged commit 7fc6365 into rust-lang:master Nov 1, 2023
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rustbot added this to the 1.75.0 milestone Nov 1, 2023

bors mentioned this pull request Nov 1, 2023

Cleanup rustc_mir_build/../check_match.rs #117343

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rustbot removed the perf-regression Performance regression. label Nov 1, 2023

Nadrieril deleted the half-open-ranges branch November 1, 2023 10:14

Nadrieril mentioned this pull request Nov 1, 2023

Tracking issue for exclusive range patterns #37854

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github-actions bot mentioned this pull request Nov 2, 2023

Automated pull from upstream master ferrocene/ferrocene#80

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Nadrieril mentioned this pull request Nov 4, 2023

Bogus "non-exhaustive patterns" error with half-open range patterns on isize/usize #111859

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Nadrieril mentioned this pull request Dec 4, 2023

Remove the precise_pointer_size_matching feature gate #118598

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Nadrieril removed the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Dec 4, 2023

Nadrieril added the relnotes Marks issues that should be documented in the release notes of the next release. label Dec 4, 2023

Nadrieril added the A-exhaustiveness-checking Relating to exhaustiveness / usefulness checking of patterns label Dec 10, 2023

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Match usize/isize exhaustively with half-open ranges #116692

Match usize/isize exhaustively with half-open ranges #116692

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Match usize/isize exhaustively with half-open ranges #116692

Match usize/isize exhaustively with half-open ranges #116692

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Overall result: ❌ regressions - no action needed

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