Constify remaining traits/impls for `const_ops` #143949

clarfonthey · 2025-07-15T01:03:23Z

Tracking issue: #143802

This is split into two commits for ease of reviewability:

Updates the forward_ref_* macros to accept multiple attributes (in anticipation of needing rust_const_unstable attributes) and also require attributes in these macros. Since the default attribute only helps for the initial implementations, it means it's easy to get wrong for future implementations, as shown for the saturating implementations which were incorrect before.
Actually constify the traits/impls.

A few random other notes on the implementation specifically:

I unindented the attributes that were passed to the forward_ref_* macro calls because in some places rustfmt wanted them to be unindented, and in others it was allowed because they were themselves inside of macro bodies. I chose the consistent indenting even though I (personally) think it looks worse.

As far as the actual changes go, this constifies the following additional traits:

Neg
Not
BitAnd
BitOr
BitXor
Shl
Shr
AddAssign
SubAssign
MulAssign
DivAssign
RemAssign
BitAndAssign
BitOrAssign
BitXorAssign
ShlAssign
ShrAssign

In terms of constified implementations of these traits, it adds the reference-forwarded versions of all the arithmetic operators, which are defined by the macros in library/core/src/internal_macros.rs. I'm not going to fully enumerate these because we'd be here all day, but sufficed to say, it effectively allows adding an & to one or both sides of an operator for primitives.

Additionally, I constified the implementations for Wrapping, Saturating, and NonZero as well, since all of them forward to already-const-stable methods. (potentially via intrinsics, to avoid extra overhead)

There are three "non-primitive" types which implement these traits, listed below. Note that I put "non-primitive" in quotes since I'm including Wrapping, Saturating, and NonZero, which are just wrappers over primitives.

Duration (arithmetic operations)
SystemTime (arithmetic operations)
Ipv4Addr (bit operations)
Ipv6Addr (bit operations)

Additionally, because the methods on SystemTime needed to make these operations const were not marked const, a separate tracking issue for const-stabilising those methods is #144517.

Stuff left out of this PR:

Assume (this could trivially be made const, but since the docs indicate this is still under heavy design, I figured I'd leave it out)
Instant (this could be made const, but cannot reasonably be constructed at constant time, so, isn't useful)
SystemTime (will submit separate PR)
SIMD types (I'm tackling these all at once later; see Constified SIMD portable-simd#467)

Note

Concerns (0 active)

~~May break Clippy~~ resolved in this comment

Managed by @rustbot—see help for details.

rustbot · 2025-07-15T01:03:27Z

r? @ibraheemdev

rustbot has assigned @ibraheemdev.
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

rustbot · 2025-07-15T01:03:31Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

src/tools/clippy/tests/ui/assign_ops.rs

library/core/src/ops/arith.rs

rustbot · 2025-07-16T22:03:02Z

Only organization members can add or resolve concerns.

samueltardieu · 2025-07-16T22:27:11Z

@rustbot concern May break Clippy

(checking if concerns work as top-level comments only, real concern was written here, and discussion about the error message is on Zulip)

samueltardieu · 2025-07-17T11:07:33Z

@rustbot resolve May break Clippy

We cleared up the misunderstanding of what the problem was.

clarfonthey · 2025-07-17T12:46:08Z

Yeah, I'll be honest, I have genuinely no idea what those tests are doing. I could just add the feature flag, but it wasn't necessary before, and I don't know why.

samueltardieu · 2025-07-17T13:16:08Z

Yeah, I'll be honest, I have genuinely no idea what those tests are doing. I could just add the feature flag, but it wasn't necessary before, and I don't know why.

Didn't you just forget to replace #![feature(const_ops)] in library/coretests/tests/lib.rs?

src/tools/clippy/tests/ui/assign_ops.rs

clarfonthey · 2025-07-18T00:00:06Z

Didn't you just forget to replace #![feature(const_ops)] in library/coretests/tests/lib.rs?

Last time I checked this file, it didn't have it, but now it does. 🤷🏻

Literally tried rg const_ops in the library folder and got nothing last time, now it worked, so, issue fixed I guess.

RalfJung · 2025-07-18T06:27:06Z

TBH I think it'd be fine to have arith and bit ops in the same feature gate. We don't need a dozen of them, and it seems likely we'd stabilize these together.

Amanieu · 2025-08-10T01:11:32Z

@bors r+

bors · 2025-08-10T01:11:35Z

📌 Commit 59a69c7 has been approved by Amanieu

It is now in the queue for this repository.

…nieu Constify remaining traits/impls for `const_ops` Tracking issue: rust-lang#143802 This is split into two commits for ease of reviewability: 1. Updates the `forward_ref_*` macros to accept multiple attributes (in anticipation of needing `rust_const_unstable` attributes) and also *require* attributes in these macros. Since the default attribute only helps for the initial implementations, it means it's easy to get wrong for future implementations, as shown for the saturating implementations which were incorrect before. 2. Actually constify the traits/impls. A few random other notes on the implementation specifically: * I unindented the attributes that were passed to the `forward_ref_*` macro calls because in some places rustfmt wanted them to be unindented, and in others it was allowed because they were themselves inside of macro bodies. I chose the consistent indenting even though I (personally) think it looks worse. ---- As far as the actual changes go, this constifies the following additional traits: * `Neg` * `Not` * `BitAnd` * `BitOr` * `BitXor` * `Shl` * `Shr` * `AddAssign` * `SubAssign` * `MulAssign` * `DivAssign` * `RemAssign` * `BitAndAssign` * `BitOrAssign` * `BitXorAssign` * `ShlAssign` * `ShrAssign` In terms of constified implementations of these traits, it adds the reference-forwarded versions of all the arithmetic operators, which are defined by the macros in `library/core/src/internal_macros.rs`. I'm not going to fully enumerate these because we'd be here all day, but sufficed to say, it effectively allows adding an `&` to one or both sides of an operator for primitives. Additionally, I constified the implementations for `Wrapping`, `Saturating`, and `NonZero` as well, since all of them forward to already-const-stable methods. (potentially via intrinsics, to avoid extra overhead) There are three "non-primitive" types which implement these traits, listed below. Note that I put "non-primitive" in quotes since I'm including `Wrapping`, `Saturating`, and `NonZero`, which are just wrappers over primitives. * `Duration` (arithmetic operations) * `SystemTime` (arithmetic operations) * `Ipv4Addr` (bit operations) * `Ipv6Addr` (bit operations) Additionally, because the methods on `SystemTime` needed to make these operations const were not marked const, a separate tracking issue for const-stabilising those methods is rust-lang#144517. Stuff left out of this PR: * `Assume` (this could trivially be made const, but since the docs indicate this is still under heavy design, I figured I'd leave it out) * `Instant` (this could be made const, but cannot reasonably be constructed at constant time, so, isn't useful) * `SystemTime` (will submit separate PR) * SIMD types (I'm tackling these all at once later; see rust-lang/portable-simd#467)   > [!NOTE] > # Concerns (0 active) > > - ~~[May break Clippy](rust-lang#143949 (comment) resolved in [this comment](rust-lang#143949 (comment)) > > *Managed by ``@rustbot`—see` [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

Zalathar · 2025-08-10T03:01:08Z

Failed in rollup due to tidy: #145192 (comment)

Probably needs a rebase.

@bors r-

…ibutes explicitly

clarfonthey · 2025-08-10T05:10:59Z

Yeah, it's the bootstrap bump making the tidy rustfmt actually use the new [const] syntax, instead of ~const.

Will rebase soon.

clarfonthey · 2025-08-10T06:30:04Z

@rustbot ready

Amanieu · 2025-08-11T01:24:13Z

@bors r+

bors · 2025-08-11T01:24:16Z

📌 Commit bb32e31 has been approved by Amanieu

It is now in the queue for this repository.

…nieu Constify remaining traits/impls for `const_ops` Tracking issue: rust-lang#143802 This is split into two commits for ease of reviewability: 1. Updates the `forward_ref_*` macros to accept multiple attributes (in anticipation of needing `rust_const_unstable` attributes) and also *require* attributes in these macros. Since the default attribute only helps for the initial implementations, it means it's easy to get wrong for future implementations, as shown for the saturating implementations which were incorrect before. 2. Actually constify the traits/impls. A few random other notes on the implementation specifically: * I unindented the attributes that were passed to the `forward_ref_*` macro calls because in some places rustfmt wanted them to be unindented, and in others it was allowed because they were themselves inside of macro bodies. I chose the consistent indenting even though I (personally) think it looks worse. ---- As far as the actual changes go, this constifies the following additional traits: * `Neg` * `Not` * `BitAnd` * `BitOr` * `BitXor` * `Shl` * `Shr` * `AddAssign` * `SubAssign` * `MulAssign` * `DivAssign` * `RemAssign` * `BitAndAssign` * `BitOrAssign` * `BitXorAssign` * `ShlAssign` * `ShrAssign` In terms of constified implementations of these traits, it adds the reference-forwarded versions of all the arithmetic operators, which are defined by the macros in `library/core/src/internal_macros.rs`. I'm not going to fully enumerate these because we'd be here all day, but sufficed to say, it effectively allows adding an `&` to one or both sides of an operator for primitives. Additionally, I constified the implementations for `Wrapping`, `Saturating`, and `NonZero` as well, since all of them forward to already-const-stable methods. (potentially via intrinsics, to avoid extra overhead) There are three "non-primitive" types which implement these traits, listed below. Note that I put "non-primitive" in quotes since I'm including `Wrapping`, `Saturating`, and `NonZero`, which are just wrappers over primitives. * `Duration` (arithmetic operations) * `SystemTime` (arithmetic operations) * `Ipv4Addr` (bit operations) * `Ipv6Addr` (bit operations) Additionally, because the methods on `SystemTime` needed to make these operations const were not marked const, a separate tracking issue for const-stabilising those methods is rust-lang#144517. Stuff left out of this PR: * `Assume` (this could trivially be made const, but since the docs indicate this is still under heavy design, I figured I'd leave it out) * `Instant` (this could be made const, but cannot reasonably be constructed at constant time, so, isn't useful) * `SystemTime` (will submit separate PR) * SIMD types (I'm tackling these all at once later; see rust-lang/portable-simd#467)   > [!NOTE] > # Concerns (0 active) > > - ~~[May break Clippy](rust-lang#143949 (comment) resolved in [this comment](rust-lang#143949 (comment)) > > *Managed by ``@rustbot`—see` [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

Rollup of 7 pull requests Successful merges: - #143949 (Constify remaining traits/impls for `const_ops`) - #144330 (document assumptions about `Clone` and `Eq` traits) - #144350 (std: sys: io: io_slice: Add UEFI types) - #144558 (Point at the `Fn()` or `FnMut()` bound that coerced a closure, which caused a move error) - #145149 (Make config method invoke inside parse use dwn_ctx) - #145227 (Tweak spans providing type context on errors when involving macros) - #145228 (Remove unnecessary parentheses in `assert!`s) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #143949 - clarfonthey:const-arith-ops, r=Amanieu Constify remaining traits/impls for `const_ops` Tracking issue: #143802 This is split into two commits for ease of reviewability: 1. Updates the `forward_ref_*` macros to accept multiple attributes (in anticipation of needing `rust_const_unstable` attributes) and also *require* attributes in these macros. Since the default attribute only helps for the initial implementations, it means it's easy to get wrong for future implementations, as shown for the saturating implementations which were incorrect before. 2. Actually constify the traits/impls. A few random other notes on the implementation specifically: * I unindented the attributes that were passed to the `forward_ref_*` macro calls because in some places rustfmt wanted them to be unindented, and in others it was allowed because they were themselves inside of macro bodies. I chose the consistent indenting even though I (personally) think it looks worse. ---- As far as the actual changes go, this constifies the following additional traits: * `Neg` * `Not` * `BitAnd` * `BitOr` * `BitXor` * `Shl` * `Shr` * `AddAssign` * `SubAssign` * `MulAssign` * `DivAssign` * `RemAssign` * `BitAndAssign` * `BitOrAssign` * `BitXorAssign` * `ShlAssign` * `ShrAssign` In terms of constified implementations of these traits, it adds the reference-forwarded versions of all the arithmetic operators, which are defined by the macros in `library/core/src/internal_macros.rs`. I'm not going to fully enumerate these because we'd be here all day, but sufficed to say, it effectively allows adding an `&` to one or both sides of an operator for primitives. Additionally, I constified the implementations for `Wrapping`, `Saturating`, and `NonZero` as well, since all of them forward to already-const-stable methods. (potentially via intrinsics, to avoid extra overhead) There are three "non-primitive" types which implement these traits, listed below. Note that I put "non-primitive" in quotes since I'm including `Wrapping`, `Saturating`, and `NonZero`, which are just wrappers over primitives. * `Duration` (arithmetic operations) * `SystemTime` (arithmetic operations) * `Ipv4Addr` (bit operations) * `Ipv6Addr` (bit operations) Additionally, because the methods on `SystemTime` needed to make these operations const were not marked const, a separate tracking issue for const-stabilising those methods is #144517. Stuff left out of this PR: * `Assume` (this could trivially be made const, but since the docs indicate this is still under heavy design, I figured I'd leave it out) * `Instant` (this could be made const, but cannot reasonably be constructed at constant time, so, isn't useful) * `SystemTime` (will submit separate PR) * SIMD types (I'm tackling these all at once later; see rust-lang/portable-simd#467)   > [!NOTE] > # Concerns (0 active) > > - ~~[May break Clippy](#143949 (comment) resolved in [this comment](#143949 (comment)) > > *Managed by ```@rustbot`—see`` [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

Zalathar · 2025-08-12T02:46:21Z

This PR appears to be linked to a perf regression observed at #145236 (comment).

(I’m not familiar with the perf triage process, but I wanted to make sure this was explicitly noted on the relevant issue and not just the rollup.)

clarfonthey · 2025-08-12T03:34:18Z

Mentioned your comment on the tracking issue since this PR has been merged; no idea how perf stuff tends to be triaged, but since wg-const-eval is looking to constify as much stuff as possible, it's probably worth bringing more visibility to it there.

rustbot assigned ibraheemdev Jul 15, 2025

This comment has been minimized.

Sign in to view

clarfonthey force-pushed the const-arith-ops branch from 97d85a1 to d7a8770 Compare July 15, 2025 02:31

This comment has been minimized.

Sign in to view

clarfonthey force-pushed the const-arith-ops branch from d7a8770 to ad7b7c4 Compare July 15, 2025 04:48

hkBst reviewed Jul 15, 2025

View reviewed changes

src/tools/clippy/tests/ui/assign_ops.rs Outdated Show resolved Hide resolved

samueltardieu reviewed Jul 15, 2025

View reviewed changes

library/core/src/ops/arith.rs Show resolved Hide resolved

clarfonthey mentioned this pull request Jul 16, 2025

Custom handling for const-stability of assign operators in assign_op_pattern lint should be removed rust-lang/rust-clippy#15285

Open

clarfonthey force-pushed the const-arith-ops branch from ad7b7c4 to 071b5f0 Compare July 16, 2025 21:50

This comment has been minimized.

Sign in to view

rustbot added the S-waiting-on-concerns Status: Awaiting concerns to be addressed by the author label Jul 16, 2025

samueltardieu mentioned this pull request Jul 16, 2025

Misleading error message when concern is left in a file comment rust-lang/triagebot#2114

Closed

rustbot removed the S-waiting-on-concerns Status: Awaiting concerns to be addressed by the author label Jul 17, 2025

clarfonthey force-pushed the const-arith-ops branch from 071b5f0 to ed0722b Compare July 17, 2025 11:59

This comment has been minimized.

Sign in to view

samueltardieu reviewed Jul 17, 2025

View reviewed changes

src/tools/clippy/tests/ui/assign_ops.rs Outdated Show resolved Hide resolved

clarfonthey force-pushed the const-arith-ops branch from ed0722b to 8e2f97b Compare July 18, 2025 00:04

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 Aug 10, 2025

Zalathar mentioned this pull request Aug 10, 2025

Rollup of 21 pull requests #145192

Closed

bors 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 Aug 10, 2025

Let forward_ref_* macros accept multiple attributes, and require attr…

f604dd1

…ibutes explicitly

Constify remaining operators

bb32e31

clarfonthey force-pushed the const-arith-ops branch from 59a69c7 to bb32e31 Compare August 10, 2025 05:11

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 Aug 10, 2025

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 Aug 11, 2025

Zalathar mentioned this pull request Aug 11, 2025

Rollup of 7 pull requests #145236

Merged

bors merged commit d06b3b4 into rust-lang:master Aug 11, 2025
10 checks passed

rustbot added this to the 1.91.0 milestone Aug 11, 2025

clarfonthey mentioned this pull request Aug 11, 2025

Tracking Issue for const_ops #143802

Open

3 tasks

clarfonthey deleted the const-arith-ops branch August 12, 2025 03:35

Constify remaining traits/impls for const_ops #143949

Constify remaining traits/impls for const_ops #143949

Uh oh!

Conversation

clarfonthey commented Jul 15, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Concerns (0 active)

Uh oh!

rustbot commented Jul 15, 2025

Uh oh!

rustbot commented Jul 15, 2025

Uh oh!

This comment has been minimized.

This comment has been minimized.

Uh oh!

Uh oh!

rustbot commented Jul 16, 2025

Uh oh!

This comment has been minimized.

samueltardieu commented Jul 16, 2025

Uh oh!

samueltardieu commented Jul 17, 2025

Uh oh!

This comment has been minimized.

clarfonthey commented Jul 17, 2025

Uh oh!

samueltardieu commented Jul 17, 2025

Uh oh!

Uh oh!

clarfonthey commented Jul 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

RalfJung commented Jul 18, 2025

Uh oh!

Amanieu commented Aug 10, 2025

Uh oh!

bors commented Aug 10, 2025

Uh oh!

Zalathar commented Aug 10, 2025

Uh oh!

clarfonthey commented Aug 10, 2025

Uh oh!

clarfonthey commented Aug 10, 2025

Uh oh!

Amanieu commented Aug 11, 2025

Uh oh!

bors commented Aug 11, 2025

Uh oh!

Uh oh!

Zalathar commented Aug 12, 2025

Uh oh!

clarfonthey commented Aug 12, 2025

Uh oh!

Uh oh!

Constify remaining traits/impls for `const_ops` #143949

Constify remaining traits/impls for `const_ops` #143949

clarfonthey commented Jul 15, 2025 •

edited

Loading

clarfonthey commented Jul 18, 2025 •

edited

Loading