Make `NonZero` constructors generic. by reitermarkus · Pull Request #120521 · rust-lang/rust

reitermarkus · 2024-01-31T07:42:56Z

This makes NonZero constructors generic, so that NonZero::new can be used without turbofish syntax.

Tracking issue: #120257

~~I cannot figure out how to make this work with const traits. Not sure if I'm using it wrong or whether there's a bug:~~

101 |         if n == T::ZERO {
    |            ^^^^^^^^^^^^ expected `host`, found `true`
    |
    = note: expected constant `host`
               found constant `true`

r? @dtolnay

library/core/src/num/nonzero.rs

Noratrieb · 2024-01-31T07:52:19Z

@rust-lang/project-const-traits looks like a bug. Should this be relying on const traits in stable code anyways, are they ready and bug free enough for that?

oli-obk · 2024-01-31T07:57:13Z

@rust-lang/project-const-traits looks like a bug.

just a diagnostics bug, the error was correct.

Should this be relying on const traits in stable code anyways, are they ready and bug free enough for that?

nope, should definitely not use them in stable code.

oli-obk

impl lgtm. the main PR message needs updating.

cc #120257 for backlinking

dtolnay

Thanks!

dtolnay · 2024-02-01T08:30:13Z

@bors r=dtolnay,oli-obk

bors · 2024-02-01T08:30:16Z

📌 Commit a5042de has been approved by dtolnay,oli-obk

It is now in the queue for this repository.

bors · 2024-02-01T08:30:16Z

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

…ructors, r=dtolnay,oli-obk Make `NonZero` constructors generic. This makes `NonZero` constructors generic, so that `NonZero::new` can be used without turbofish syntax. Tracking issue: rust-lang#120257 ~~I cannot figure out how to make this work with `const` traits. Not sure if I'm using it wrong or whether there's a bug:~~ ```rust 101 | if n == T::ZERO { | ^^^^^^^^^^^^ expected `host`, found `true` | = note: expected constant `host` found constant `true` ``` r? `@dtolnay`

…ructors, r=dtolnay,oli-obk Make `NonZero` constructors generic. This makes `NonZero` constructors generic, so that `NonZero::new` can be used without turbofish syntax. Tracking issue: rust-lang#120257 ~~I cannot figure out how to make this work with `const` traits. Not sure if I'm using it wrong or whether there's a bug:~~ ```rust 101 | if n == T::ZERO { | ^^^^^^^^^^^^ expected `host`, found `true` | = note: expected constant `host` found constant `true` ``` r? ``@dtolnay``

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#120507 (Account for non-overlapping unmet trait bounds in suggestion) - rust-lang#120518 (riscv only supports split_debuginfo=off for now) - rust-lang#120521 (Make `NonZero` constructors generic.) - rust-lang#120527 (Switch OwnedStore handle count to AtomicU32) - rust-lang#120550 (Continue to borrowck even if there were previous errors) - rust-lang#120587 (miri: normalize struct tail in ABI compat check) - rust-lang#120590 (Remove unused args from functions) - rust-lang#120607 (fix rust-lang#120603 by adding a check in default_read_buf) Failed merges: - rust-lang#120575 (Simplify codegen diagnostic handling) r? `@ghost` `@rustbot` modify labels: rollup

…ructors, r=dtolnay,oli-obk Make `NonZero` constructors generic. This makes `NonZero` constructors generic, so that `NonZero::new` can be used without turbofish syntax. Tracking issue: rust-lang#120257 ~~I cannot figure out how to make this work with `const` traits. Not sure if I'm using it wrong or whether there's a bug:~~ ```rust 101 | if n == T::ZERO { | ^^^^^^^^^^^^ expected `host`, found `true` | = note: expected constant `host` found constant `true` ``` r? ```@dtolnay```

bors · 2024-02-07T15:15:30Z

💡 This pull request was already approved, no need to approve it again.

There's another pull request that is currently being tested, blocking this pull request: Use the same mir-opt bless targets on all platforms #120060

bors · 2024-02-07T15:15:31Z

📌 Commit 4229875 has been approved by dtolnay

It is now in the queue for this repository.

bors · 2024-02-08T03:00:36Z

⌛ Testing commit 4229875 with merge 384b02c...

bors · 2024-02-08T05:00:00Z

☀️ Test successful - checks-actions
Approved by: dtolnay
Pushing 384b02c to master...

rust-timer · 2024-02-08T06:55:53Z

Finished benchmarking commit (384b02c): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.7%	[0.4%, 1.7%]	9
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-1.3%	[-1.3%, -1.3%]	1
All ❌✅ (primary)	0.5%	[-1.0%, 1.7%]	10

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)	3.3%	[0.2%, 7.0%]	3
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-3.0%	[-3.0%, -3.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.8%	[-3.0%, 7.0%]	4

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)	1.1%	[0.6%, 1.7%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.1%	[0.6%, 1.7%]	3

Binary size

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)	0.1%	[0.0%, 0.8%]	30
Regressions ❌ (secondary)	0.9%	[0.9%, 1.0%]	3
Improvements ✅ (primary)	-0.2%	[-0.7%, -0.0%]	15
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.0%	[-0.7%, 0.8%]	45

Bootstrap: 663.461s -> 663.578s (0.02%)
Artifact size: 308.30 MiB -> 308.27 MiB (-0.01%)

scottmcm · 2024-02-08T08:52:58Z

library/core/src/num/nonzero.rs

+    pub const fn new(n: T) -> Option<Self> {
+        // SAFETY: Memory layout optimization guarantees that `Option<NonZero<T>>` has
+        //         the same layout and size as `T`, with `0` representing `None`.
+        unsafe { ptr::read(ptr::addr_of!(n).cast()) }


This looks like a reimplementation of either transmute_copy or intrinsics::transmute_unchecked?

it used to be. I assume this was changed to be able to remove the #[rustc_allow_const_fn_unstable(const_refs_to_cell)], but then that wasn't removed 😆

No, it was changed to fix the failing niche-filling.rs test, caused by the assert! call in transmute_copy. Maybe transmute_unchecked is what I was looking for.

I tried removing #[rustc_allow_const_fn_unstable(const_refs_to_cell)] as well, but it seems to be used by addr_of!.

…ructors, r=Nilstrieb Use `transmute_unchecked` in `NonZero::new`. Tracking issue: rust-lang#120257 See rust-lang#120521 (comment).

Rollup merge of rust-lang#120809 - reitermarkus:generic-nonzero-constructors, r=Nilstrieb Use `transmute_unchecked` in `NonZero::new`. Tracking issue: rust-lang#120257 See rust-lang#120521 (comment).

…r=Nilstrieb Use `transmute_unchecked` in `NonZero::new`. Tracking issue: rust-lang/rust#120257 See rust-lang/rust#120521 (comment).

Kobzol · 2024-02-13T07:48:25Z

Regression mostly resolved by #120809.

@rustbot label: +perf-regression-triaged

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? `@dtolnay`

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? ``@dtolnay``

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? ```@dtolnay```

…dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? `@dtolnay`

Make `NonZero::get` generic. Tracking issue: rust-lang/rust#120257 Depends on rust-lang/rust#120521. r? `@dtolnay`

rustbot assigned dtolnay Jan 31, 2024

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 Jan 31, 2024

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reitermarkus force-pushed the generic-nonzero-constructors branch from cf74423 to a5042de Compare January 31, 2024 09:07

reitermarkus requested review from dtolnay and oli-obk February 1, 2024 07:47

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 1, 2024

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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 Feb 1, 2024

This was referenced Feb 1, 2024

Tracking Issue for generic NonZero #120257

Closed

Make NonZero::get generic. #120563

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matthiaskrgr mentioned this pull request Feb 3, 2024

Rollup of 9 pull requests #120621

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matthiaskrgr mentioned this pull request Feb 4, 2024

Rollup of 8 pull requests #120651

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matthiaskrgr mentioned this pull request Feb 5, 2024

Rollup of 9 pull requests #120662

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bors added the merged-by-bors This PR was explicitly merged by bors. label Feb 8, 2024

bors merged commit 384b02c into rust-lang:master Feb 8, 2024

rustbot added this to the 1.78.0 milestone Feb 8, 2024

This was referenced Feb 8, 2024

Toggle assert_unsafe_precondition in codegen instead of expansion #120594

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Bump bootstrap compiler to just-built 1.77 beta #120676

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rustbot added the perf-regression Performance regression. label Feb 8, 2024

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reitermarkus mentioned this pull request Feb 8, 2024

Use transmute_unchecked in NonZero::new. #120809

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rustbot added the perf-regression-triaged The performance regression has been triaged. label Feb 13, 2024

oli-obk added a commit to oli-obk/rust that referenced this pull request Feb 13, 2024

Rollup merge of rust-lang#120563 - reitermarkus:generic-nonzero-get, …

10a5d53

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? `@dtolnay`

oli-obk added a commit to oli-obk/rust that referenced this pull request Feb 13, 2024

Rollup merge of rust-lang#120563 - reitermarkus:generic-nonzero-get, …

743f52f

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? ``@dtolnay``

oli-obk added a commit to oli-obk/rust that referenced this pull request Feb 15, 2024

Rollup merge of rust-lang#120563 - reitermarkus:generic-nonzero-get, …

1f1d765

…r=dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? ```@dtolnay```

bors added a commit to rust-lang-ci/rust that referenced this pull request Feb 16, 2024

Auto merge of rust-lang#120563 - reitermarkus:generic-nonzero-get, r=…

439d69c

…dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? `@dtolnay`

bors added a commit to rust-lang-ci/rust that referenced this pull request Feb 17, 2024

Auto merge of rust-lang#120563 - reitermarkus:generic-nonzero-get, r=…

4316d0c

…dtolnay Make `NonZero::get` generic. Tracking issue: rust-lang#120257 Depends on rust-lang#120521. r? `@dtolnay`

github-actions bot pushed a commit to rust-lang/miri that referenced this pull request Feb 17, 2024

Auto merge of #120563 - reitermarkus:generic-nonzero-get, r=dtolnay

efa8c32

Make `NonZero::get` generic. Tracking issue: rust-lang/rust#120257 Depends on rust-lang/rust#120521. r? `@dtolnay`

lnicola pushed a commit to lnicola/rust-analyzer that referenced this pull request Apr 7, 2024

Auto merge of #120563 - reitermarkus:generic-nonzero-get, r=dtolnay

e9b04cc

Make `NonZero::get` generic. Tracking issue: rust-lang/rust#120257 Depends on rust-lang/rust#120521. r? `@dtolnay`

RalfJung pushed a commit to RalfJung/rust-analyzer that referenced this pull request Apr 27, 2024

Auto merge of #120563 - reitermarkus:generic-nonzero-get, r=dtolnay

9d527db

Make `NonZero::get` generic. Tracking issue: rust-lang/rust#120257 Depends on rust-lang/rust#120521. r? `@dtolnay`

scottmcm mentioned this pull request Dec 31, 2025

Missed NonZero optimization opportunity #60044

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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