Require `#[const_trait]` on `Trait` for `impl const Trait` #100982

fee1-dead · 2022-08-25T03:01:40Z

compiler/rustc_passes/src/check_const.rs

oli-obk · 2022-08-25T07:43:31Z

309 | static RT: Lazy<Mutex<Runtime>> = Lazy::new(Default::default);
    |                                   --------- ^^^^^^^^^^^^^^^^ the trait `~const Default` is not implemented for `Mutex<Runtime>`
    |                                   required by a bound introduced by this call

oh fun, adding #[const_trait] is a breaking change right now because all uses of the trait in const contexts will now assume we need ~const Trait. This is somewhat why I really want constness to be a generic param, so we can have an Infer variant that will only fall back to the context after all other inference is done.

fee1-dead · 2022-08-25T09:13:36Z

This is somewhat why I really want constness to be a generic param, so we can have an Infer variant that will only fall back to the context after all other inference is done.

Does that help? This error occurs in a static, so it is a const context. It just has to be fixed I think.

oli-obk · 2022-08-25T09:26:22Z

This error occurs in a static, so it is a const context. It just has to be fixed I think.

yes, but inference would figure out that we require NotConst for the Default::default since the return type is NotConst. I don't quite know how to fix this in general. I mean users could be writing let x = Default::default; and at that point you have no idea whether you need const or not const and don't even know the other concrete generic params yet, so you don't know whether it can even be const. We need to delay figuring out the constness until a concrete type is known.

Hmm or are you saying we could not error and instead replace the obligation with a notconst one?

fee1-dead · 2022-08-25T09:28:17Z

let x = Default::default; shouldn't require the Self type to be const, right? Unless we are talking about const fn pointers

oli-obk · 2022-08-25T09:31:39Z

let x = Default::default; shouldn't require the Self type to be const, right? Unless we are talking about const fn pointers

hmm good point, until we have those we can just always require notconst

rustbot · 2022-09-10T08:05:35Z

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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fee1-dead · 2022-09-10T08:06:20Z

@bors try @rust-timer queue

rust-timer · 2022-09-10T08:06:21Z

Awaiting bors try build completion.

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

bors · 2022-09-10T08:06:29Z

⌛ Trying commit 8778c414246fd13fa8f821f6d18e5a8c77f34ffa with merge ba5e1059d3d194a4ca86d8515dffc9ab53379ea9...

bors · 2022-09-10T09:56:51Z

☀️ Try build successful - checks-actions
Build commit: ba5e1059d3d194a4ca86d8515dffc9ab53379ea9 (ba5e1059d3d194a4ca86d8515dffc9ab53379ea9)

rust-timer · 2022-09-10T09:56:53Z

Queued ba5e1059d3d194a4ca86d8515dffc9ab53379ea9 with parent cedd26b, future comparison URL.

rust-timer · 2022-09-10T16:59:11Z

Finished benchmarking commit (ba5e1059d3d194a4ca86d8515dffc9ab53379ea9): comparison URL.

Overall result: ❌ regressions - 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-review -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.

	mean¹	range	count²
Regressions ❌ (primary)	0.7%	[0.3%, 1.5%]	10
Regressions ❌ (secondary)	3.2%	[2.0%, 3.9%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.7%	[0.3%, 1.5%]	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.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.5%	[0.8%, 2.2%]	2
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-1.6%	[-1.6%, -1.6%]	1
All ❌✅ (primary)	-2.7%	[-2.7%, -2.7%]	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.

	mean¹	range	count²
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	3.1%	[2.2%, 5.2%]	5
Improvements ✅ (primary)	-1.9%	[-1.9%, -1.9%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[-1.9%, 2.0%]	2

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

Again, implementing `const Trait` requires `Trait` to be marked with `#[const_trait]` starting from [rust-lang/rust#100982][1]. [1]: rust-lang/rust#100982

…_trait]` `[ref:const_impl_of_non_const_trait]` has been resolved by [rust-lang/rust#100982][1]. [1]: rust-lang/rust#100982

Upgrade the Rust version from 1.62.0 to 1.66.0. The overwhelming majority of the commit is about upgrading our `alloc` fork to the new version from upstream [1]. License has not changed [2][3] (there were changes in the `COPYRIGHT` file, but unrelated to `alloc`). As in the previous version upgrades (done out of tree so far), upgrading `alloc` requires checking that our small additions (`try_*`) still match their original (non`-try_*`) versions. With this version upgrade, the following unstable Rust features were stabilized: `bench_black_box` (1.66.0), `const_ptr_offset_from` (1.65.0), `core_ffi_c` (1.64.0) and `generic_associated_types` (1.65.0). Thus remove them. This also implies that only two unstable features remain allowed for non-`rust/` code: `allocator_api` and `const_refs_to_cell`. There are some new Clippy warnings that we are triggering (i.e. introduced since 1.62.0), as well as a few others that were not triggered before, thus allow them in this commit and clean up or remove them as needed later on: - `borrow_deref_ref` (new in 1.63.0). - `explicit_auto_deref` (new in 1.64.0). - `bool_to_int_with_if` (new in 1.65.0). - `needless_borrow`. - `type_complexity`. - `unnecessary_cast` (allowed only on `CONFIG_ARM`). Furthermore, `rustdoc` lint `broken_intra_doc_links` is triggering on links pointing to `macro_export` `macro_rules` defined in the same module (i.e. appearing in the crate root). However, even if the warning appears, the link still gets generated like in previous versions, thus it is a bit confusing. An issue has been opened upstream [4], and it appears that the link still being generated was a compatibility measure, thus we will need to adapt to the new behavior (done in the next patch). In addition, there is an added `#[const_trait]` attribute in `RawDeviceId`, due to 1.66.0's PR "Require `#[const_trait]` on `Trait` for `impl const Trait`") [5]. Finally, the `-Aunused-imports` was added for compiling `core`. This was fixed upstream for 1.67.0 in PR "Fix warning when libcore is compiled with no_fp_fmt_parse" [6], and prevented for the future for that `cfg` in PR "core: ensure `no_fp_fmt_parse builds` are warning-free" [7]. Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Tested-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Tested-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Reviewed-by: Neal Gompa <neal@gompa.dev> Tested-by: Neal Gompa <neal@gompa.dev> Link: Rust-for-Linux#947 Link: https://github.com/rust-lang/rust/tree/1.66.0/library/alloc/src [1] Link: https://github.com/rust-lang/rust/blob/1.66.0/library/alloc/Cargo.toml#L4 [2] Link: https://github.com/rust-lang/rust/blob/1.66.0/COPYRIGHT [3] Link: rust-lang/rust#106142 [4] Link: rust-lang/rust#100982 [5] Link: rust-lang/rust#105434 [6] Link: rust-lang/rust#105811 [7] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Upgrade the Rust version from 1.62.0 to 1.66.0. The overwhelming majority of the commit is about upgrading our `alloc` fork to the new version from upstream [1]. License has not changed [2][3] (there were changes in the `COPYRIGHT` file, but unrelated to `alloc`). As in the previous version upgrades (done out of tree so far), upgrading `alloc` requires checking that our small additions (`try_*`) still match their original (non`-try_*`) versions. With this version upgrade, the following unstable Rust features were stabilized: `bench_black_box` (1.66.0), `const_ptr_offset_from` (1.65.0), `core_ffi_c` (1.64.0) and `generic_associated_types` (1.65.0). Thus remove them. This also implies that only two unstable features remain allowed for non-`rust/` code: `allocator_api` and `const_refs_to_cell`. There are some new Clippy warnings that we are triggering (i.e. introduced since 1.62.0), as well as a few others that were not triggered before, thus allow them in this commit and clean up or remove them as needed later on: - `borrow_deref_ref` (new in 1.63.0). - `explicit_auto_deref` (new in 1.64.0). - `bool_to_int_with_if` (new in 1.65.0). - `needless_borrow`. - `type_complexity`. - `unnecessary_cast` (allowed only on `CONFIG_ARM`). Furthermore, `rustdoc` lint `broken_intra_doc_links` is triggering on links pointing to `macro_export` `macro_rules` defined in the same module (i.e. appearing in the crate root). However, even if the warning appears, the link still gets generated like in previous versions, thus it is a bit confusing. An issue has been opened upstream [4], and it appears that the link still being generated was a compatibility measure, thus we will need to adapt to the new behavior (done in the next patch). In addition, there is an added `#[const_trait]` attribute in `RawDeviceId`, due to 1.66.0's PR "Require `#[const_trait]` on `Trait` for `impl const Trait`") [5]. Finally, the `-Aunused-imports` was added for compiling `core`. This was fixed upstream for 1.67.0 in PR "Fix warning when libcore is compiled with no_fp_fmt_parse" [6], and prevented for the future for that `cfg` in PR "core: ensure `no_fp_fmt_parse builds` are warning-free" [7]. Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Tested-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Tested-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Reviewed-by: Neal Gompa <neal@gompa.dev> Tested-by: Neal Gompa <neal@gompa.dev> Link: Rust-for-Linux/linux#947 Link: https://github.com/rust-lang/rust/tree/1.66.0/library/alloc/src [1] Link: https://github.com/rust-lang/rust/blob/1.66.0/library/alloc/Cargo.toml#L4 [2] Link: https://github.com/rust-lang/rust/blob/1.66.0/COPYRIGHT [3] Link: rust-lang/rust#106142 [4] Link: rust-lang/rust#100982 [5] Link: rust-lang/rust#105434 [6] Link: rust-lang/rust#105811 [7] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Upgrade the Rust version from 1.62.0 to 1.66.0. The overwhelming majority of the commit is about upgrading our `alloc` fork to the new version from upstream [1]. License has not changed [2][3] (there were changes in the `COPYRIGHT` file, but unrelated to `alloc`). As in the previous version upgrades (done out of tree so far), upgrading `alloc` requires checking that our small additions (`try_*`) still match their original (non`-try_*`) versions. With this version upgrade, the following unstable Rust features were stabilized: `bench_black_box` (1.66.0), `const_ptr_offset_from` (1.65.0), `core_ffi_c` (1.64.0) and `generic_associated_types` (1.65.0). Thus remove them. This also implies that only two unstable features remain allowed for non-`rust/` code: `allocator_api` and `const_refs_to_cell`. There are some new Clippy warnings that we are triggering (i.e. introduced since 1.62.0), as well as a few others that were not triggered before, thus allow them in this commit and clean up or remove them as needed later on: - `borrow_deref_ref` (new in 1.63.0). - `explicit_auto_deref` (new in 1.64.0). - `bool_to_int_with_if` (new in 1.65.0). - `needless_borrow`. - `type_complexity`. - `unnecessary_cast` (allowed only on `CONFIG_ARM`). Furthermore, `rustdoc` lint `broken_intra_doc_links` is triggering on links pointing to `macro_export` `macro_rules` defined in the same module (i.e. appearing in the crate root). However, even if the warning appears, the link still gets generated like in previous versions, thus it is a bit confusing. An issue has been opened upstream [4], and it appears that the link still being generated was a compatibility measure, thus we will need to adapt to the new behavior (done in the next patch). In addition, there is an added `#[const_trait]` attribute in `RawDeviceId`, due to 1.66.0's PR "Require `#[const_trait]` on `Trait` for `impl const Trait`") [5]. Finally, the `-Aunused-imports` was added for compiling `core`. This was fixed upstream for 1.67.0 in PR "Fix warning when libcore is compiled with no_fp_fmt_parse" [6], and prevented for the future for that `cfg` in PR "core: ensure `no_fp_fmt_parse builds` are warning-free" [7]. Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Tested-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Tested-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Reviewed-by: Neal Gompa <neal@gompa.dev> Tested-by: Neal Gompa <neal@gompa.dev> Link: Rust-for-Linux#947 Link: https://github.com/rust-lang/rust/tree/1.66.0/library/alloc/src [1] Link: https://github.com/rust-lang/rust/blob/1.66.0/library/alloc/Cargo.toml#L4 [2] Link: https://github.com/rust-lang/rust/blob/1.66.0/COPYRIGHT [3] Link: rust-lang/rust#106142 [4] Link: rust-lang/rust#100982 [5] Link: rust-lang/rust#105434 [6] Link: rust-lang/rust#105811 [7] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Upgrade the Rust version from 1.62.0 to 1.66.0. The overwhelming majority of the commit is about upgrading our `alloc` fork to the new version from upstream [1]. License has not changed [2][3] (there were changes in the `COPYRIGHT` file, but unrelated to `alloc`). As in the previous version upgrades (done out of tree so far), upgrading `alloc` requires checking that our small additions (`try_*`) still match their original (non`-try_*`) versions. With this version upgrade, the following unstable Rust features were stabilized: `bench_black_box` (1.66.0), `const_ptr_offset_from` (1.65.0), `core_ffi_c` (1.64.0) and `generic_associated_types` (1.65.0). Thus remove them. This also implies that only two unstable features remain allowed for non-`rust/` code: `allocator_api` and `const_refs_to_cell`. There are some new Clippy warnings that we are triggering (i.e. introduced since 1.62.0), as well as a few others that were not triggered before, thus allow them in this commit and clean up or remove them as needed later on: - `borrow_deref_ref` (new in 1.63.0). - `explicit_auto_deref` (new in 1.64.0). - `bool_to_int_with_if` (new in 1.65.0). - `needless_borrow`. - `type_complexity`. - `unnecessary_cast` (allowed only on `CONFIG_ARM`). Furthermore, `rustdoc` lint `broken_intra_doc_links` is triggering on links pointing to `macro_export` `macro_rules` defined in the same module (i.e. appearing in the crate root). However, even if the warning appears, the link still gets generated like in previous versions, thus it is a bit confusing. An issue has been opened upstream [4], and it appears that the link still being generated was a compatibility measure, thus we will need to adapt to the new behavior (done in the next patch). In addition, there is an added `#[const_trait]` attribute in `RawDeviceId`, due to 1.66.0's PR "Require `#[const_trait]` on `Trait` for `impl const Trait`") [5]. Finally, the `-Aunused-imports` was added for compiling `core`. This was fixed upstream for 1.67.0 in PR "Fix warning when libcore is compiled with no_fp_fmt_parse" [6], and prevented for the future for that `cfg` in PR "core: ensure `no_fp_fmt_parse builds` are warning-free" [7]. Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Tested-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Reviewed-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Tested-by: Alice Ferrazzi <alice.ferrazzi@miraclelinux.com> Reviewed-by: Neal Gompa <neal@gompa.dev> Tested-by: Neal Gompa <neal@gompa.dev> Link: Rust-for-Linux/linux#947 Link: https://github.com/rust-lang/rust/tree/1.66.0/library/alloc/src [1] Link: https://github.com/rust-lang/rust/blob/1.66.0/library/alloc/Cargo.toml#L4 [2] Link: https://github.com/rust-lang/rust/blob/1.66.0/COPYRIGHT [3] Link: rust-lang/rust#106142 [4] Link: rust-lang/rust#100982 [5] Link: rust-lang/rust#105434 [6] Link: rust-lang/rust#105811 [7] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust-highfive assigned oli-obk Aug 25, 2022

rustbot added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Aug 25, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 25, 2022

fee1-dead marked this pull request as draft August 25, 2022 03:01

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fee1-dead marked this pull request as ready for review September 10, 2022 08:05

rustbot added the perf-regression Performance regression. label Sep 10, 2022

fee1-dead force-pushed the const-impl-requires-const-trait branch from a28780a to 3bd8f51 Compare September 15, 2022 16:13

yvt added a commit to r3-os/r3 that referenced this pull request Nov 10, 2022

test(toolchain_limitations): impl const Trait now requires `#[const…

b78f660

…_trait]` `[ref:const_impl_of_non_const_trait]` has been resolved by [rust-lang/rust#100982][1]. [1]: rust-lang/rust#100982

ojeda mentioned this pull request Dec 26, 2022

rust: upgrade to Rust 1.66.0 Rust-for-Linux/linux#947

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Require `#[const_trait]` on `Trait` for `impl const Trait` #100982

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Require #[const_trait] on Trait for impl const Trait #100982

Require #[const_trait] on Trait for impl const Trait #100982

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Overall result: ❌ regressions - ACTION NEEDED

Instruction count

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Require `#[const_trait]` on `Trait` for `impl const Trait` #100982

Require `#[const_trait]` on `Trait` for `impl const Trait` #100982

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