New const traits syntax #139858

oli-obk · 2025-04-15T09:02:09Z

This PR only affects the AST and doesn't actually change anything semantically.

All occurrences of ~const outside of libcore have been replaced by [const]. Within libcore we have to wait for rustfmt to be bumped in the bootstrap compiler. This will happen "automatically" (when rustfmt is run) during the bootstrap bump, as rustfmt converts ~const into [const]. After this we can remove the ~const support from the parser

Caveat discovered during impl: there is no legacy bare trait object recovery for [const] Trait as that snippet in type position goes down the slice /array parsing code and will error

r? @fee1-dead

cc @nikomatsakis @traviscross @compiler-errors

rustbot · 2025-04-15T09:02:17Z

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

compiler/rustc_ast/src/ast.rs

tests/ui/const-generics/const_trait_fn-issue-88433.rs

src/tools/clippy/clippy_utils/src/ast_utils/mod.rs

bors · 2025-05-06T10:43:05Z

☔ The latest upstream changes (presumably #140695) made this pull request unmergeable. Please resolve the merge conflicts.

compiler-errors · 2025-05-22T09:37:39Z

Have we actually settled on a syntax here? Sorry for punting it back over, but would like to get an update here if it's actually ready to review :> ping me when it's ready, sorry for the delays!

@rustbot author

rustbot · 2025-05-22T09:37:43Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

traviscross · 2025-05-22T14:34:16Z

Have we actually settled on a syntax here?

No. Discussion is ongoing.

rustbot · 2025-06-26T10:45:28Z

There are changes to the tidy tool.

cc @jieyouxu

fee1-dead · 2025-06-27T09:35:17Z

@bors r+ rollup=never

bors · 2025-06-27T09:35:21Z

📌 Commit 512ff95 has been approved by fee1-dead

It is now in the queue for this repository.

compiler-errors · 2025-06-27T17:01:36Z

This affects a lot of tests but I don't expect it to fail, except if there's an untested doc test or something.

@bors rollup=iffy

…=fee1-dead New const traits syntax This PR only affects the AST and doesn't actually change anything semantically. All occurrences of `~const` outside of libcore have been replaced by `[const]`. Within libcore we have to wait for rustfmt to be bumped in the bootstrap compiler. This will happen "automatically" (when rustfmt is run) during the bootstrap bump, as rustfmt converts `~const` into `[const]`. After this we can remove the `~const` support from the parser Caveat discovered during impl: there is no legacy bare trait object recovery for `[const] Trait` as that snippet in type position goes down the slice /array parsing code and will error r? `@fee1-dead` cc `@nikomatsakis` `@traviscross` `@compiler-errors`

…rors Rollup of 8 pull requests Successful merges: - #139858 (New const traits syntax) - #140809 (Reduce special casing for the panic runtime) - #142963 (Skip unnecessary components in x64 try builds) - #142974 (Update stage0 to 1.89.0-beta.1) - #142987 (rustdoc: show attributes on enum variants) - #143002 (tests: Require `run-fail` ui tests to have an exit code (`SIGABRT` not ok)) - #143092 (const checks for lifetime-extended temporaries: avoid 'top-level scope' terminology) - #143096 (tag_for_variant: properly pass TypingEnv) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 9 pull requests Successful merges: - #139858 (New const traits syntax) - #140809 (Reduce special casing for the panic runtime) - #142730 (suggest declaring modules when file found but module not defined) - #142806 (Normalize before computing ConstArgHasType goal in new solver) - #143046 (const validation: properly ignore zero-sized UnsafeCell) - #143092 (const checks for lifetime-extended temporaries: avoid 'top-level scope' terminology) - #143096 (tag_for_variant: properly pass TypingEnv) - #143104 (hir_analysis: prohibit `dyn PointeeSized`) - #143106 (gce: don't ICE on non-local const) Failed merges: - #143036 (Remove support for `dyn*` from the compiler) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-06-28T02:19:45Z

⌛ Testing commit 512ff95 with merge d41e12f...

Rollup merge of #139858 - oli-obk:new-const-traits-syntax, r=fee1-dead New const traits syntax This PR only affects the AST and doesn't actually change anything semantically. All occurrences of `~const` outside of libcore have been replaced by `[const]`. Within libcore we have to wait for rustfmt to be bumped in the bootstrap compiler. This will happen "automatically" (when rustfmt is run) during the bootstrap bump, as rustfmt converts `~const` into `[const]`. After this we can remove the `~const` support from the parser Caveat discovered during impl: there is no legacy bare trait object recovery for `[const] Trait` as that snippet in type position goes down the slice /array parsing code and will error r? ``@fee1-dead`` cc ``@nikomatsakis`` ``@traviscross`` ``@compiler-errors``

Rollup of 9 pull requests Successful merges: - rust-lang/rust#139858 (New const traits syntax) - rust-lang/rust#140809 (Reduce special casing for the panic runtime) - rust-lang/rust#142730 (suggest declaring modules when file found but module not defined) - rust-lang/rust#142806 (Normalize before computing ConstArgHasType goal in new solver) - rust-lang/rust#143046 (const validation: properly ignore zero-sized UnsafeCell) - rust-lang/rust#143092 (const checks for lifetime-extended temporaries: avoid 'top-level scope' terminology) - rust-lang/rust#143096 (tag_for_variant: properly pass TypingEnv) - rust-lang/rust#143104 (hir_analysis: prohibit `dyn PointeeSized`) - rust-lang/rust#143106 (gce: don't ICE on non-local const) Failed merges: - rust-lang/rust#143036 (Remove support for `dyn*` from the compiler) r? `@ghost` `@rustbot` modify labels: rollup

…=fee1-dead New const traits syntax This PR only affects the AST and doesn't actually change anything semantically. All occurrences of `~const` outside of libcore have been replaced by `[const]`. Within libcore we have to wait for rustfmt to be bumped in the bootstrap compiler. This will happen "automatically" (when rustfmt is run) during the bootstrap bump, as rustfmt converts `~const` into `[const]`. After this we can remove the `~const` support from the parser Caveat discovered during impl: there is no legacy bare trait object recovery for `[const] Trait` as that snippet in type position goes down the slice /array parsing code and will error r? ``@fee1-dead`` cc ``@nikomatsakis`` ``@traviscross`` ``@compiler-errors``

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [syn](https://redirect.github.com/dtolnay/syn) | workspace.dependencies | patch | `2.0.104` -> `2.0.106` | --- ### Release Notes <details> <summary>dtolnay/syn (syn)</summary> ### [`v2.0.106`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.106) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.105...2.0.106) - Replace `~const` syntax with `[const]` conditionally const syntax in trait bounds ([#1896](https://redirect.github.com/dtolnay/syn/issues/1896), [rust-lang/rust#139858](https://redirect.github.com/rust-lang/rust/pull/139858)) - Support conditionally const impl Trait types ([#1897](https://redirect.github.com/dtolnay/syn/issues/1897)) - Reject polarity modifier and lifetime binder used in the same trait bound ([#1899](https://redirect.github.com/dtolnay/syn/issues/1899), [rust-lang/rust#127054](https://redirect.github.com/rust-lang/rust/pull/127054)) - Parse const trait bounds with bound lifetimes ([#1902](https://redirect.github.com/dtolnay/syn/issues/1902)) - Parse bound lifetimes with lifetime bounds ([#1903](https://redirect.github.com/dtolnay/syn/issues/1903)) - Allow type parameters and const parameters in trait bounds and generic closures ([#1904](https://redirect.github.com/dtolnay/syn/issues/1904), [#1907](https://redirect.github.com/dtolnay/syn/issues/1907), [#1908](https://redirect.github.com/dtolnay/syn/issues/1908), [#1909](https://redirect.github.com/dtolnay/syn/issues/1909)) ### [`v2.0.105`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.105) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.104...2.0.105) - Disallow "negative" inherent impls like `impl !T {}` ([#1881](https://redirect.github.com/dtolnay/syn/issues/1881), [rust-lang/rust#144386](https://redirect.github.com/rust-lang/rust/pull/144386)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - Between 12:00 AM and 05:59 AM, on day 24 of the month ( * 0-5 24 * * ) (UTC), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR was generated by [Mend Renovate](https://mend.io/renovate/). View the [repository job log](https://developer.mend.io/github/jerus-org/captval).

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [syn](https://redirect.github.com/dtolnay/syn) | workspace.dependencies | patch | `2.0.104` -> `2.0.106` | --- > [!WARNING] > Some dependencies could not be looked up. Check the Dependency Dashboard for more information. --- ### Release Notes <details> <summary>dtolnay/syn (syn)</summary> ### [`v2.0.106`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.106) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.105...2.0.106) - Replace `~const` syntax with `[const]` conditionally const syntax in trait bounds ([#1896](https://redirect.github.com/dtolnay/syn/issues/1896), [rust-lang/rust#139858](https://redirect.github.com/rust-lang/rust/pull/139858)) - Support conditionally const impl Trait types ([#1897](https://redirect.github.com/dtolnay/syn/issues/1897)) - Reject polarity modifier and lifetime binder used in the same trait bound ([#1899](https://redirect.github.com/dtolnay/syn/issues/1899), [rust-lang/rust#127054](https://redirect.github.com/rust-lang/rust/pull/127054)) - Parse const trait bounds with bound lifetimes ([#1902](https://redirect.github.com/dtolnay/syn/issues/1902)) - Parse bound lifetimes with lifetime bounds ([#1903](https://redirect.github.com/dtolnay/syn/issues/1903)) - Allow type parameters and const parameters in trait bounds and generic closures ([#1904](https://redirect.github.com/dtolnay/syn/issues/1904), [#1907](https://redirect.github.com/dtolnay/syn/issues/1907), [#1908](https://redirect.github.com/dtolnay/syn/issues/1908), [#1909](https://redirect.github.com/dtolnay/syn/issues/1909)) ### [`v2.0.105`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.105) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.104...2.0.105) - Disallow "negative" inherent impls like `impl !T {}` ([#1881](https://redirect.github.com/dtolnay/syn/issues/1881), [rust-lang/rust#144386](https://redirect.github.com/rust-lang/rust/pull/144386)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - "before 4am on Monday" (UTC), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR was generated by [Mend Renovate](https://mend.io/renovate/). View the [repository job log](https://developer.mend.io/github/astral-sh/ruff).  Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [syn](https://redirect.github.com/dtolnay/syn) | workspace.dependencies | patch | `2.0.104` -> `2.0.106` | --- > [!WARNING] > Some dependencies could not be looked up. Check the Dependency Dashboard for more information. --- ### Release Notes <details> <summary>dtolnay/syn (syn)</summary> ### [`v2.0.106`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.106) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.105...2.0.106) - Replace `~const` syntax with `[const]` conditionally const syntax in trait bounds ([#1896](https://redirect.github.com/dtolnay/syn/issues/1896), [rust-lang/rust#139858](https://redirect.github.com/rust-lang/rust/pull/139858)) - Support conditionally const impl Trait types ([#1897](https://redirect.github.com/dtolnay/syn/issues/1897)) - Reject polarity modifier and lifetime binder used in the same trait bound ([#1899](https://redirect.github.com/dtolnay/syn/issues/1899), [rust-lang/rust#127054](https://redirect.github.com/rust-lang/rust/pull/127054)) - Parse const trait bounds with bound lifetimes ([#1902](https://redirect.github.com/dtolnay/syn/issues/1902)) - Parse bound lifetimes with lifetime bounds ([#1903](https://redirect.github.com/dtolnay/syn/issues/1903)) - Allow type parameters and const parameters in trait bounds and generic closures ([#1904](https://redirect.github.com/dtolnay/syn/issues/1904), [#1907](https://redirect.github.com/dtolnay/syn/issues/1907), [#1908](https://redirect.github.com/dtolnay/syn/issues/1908), [#1909](https://redirect.github.com/dtolnay/syn/issues/1909)) ### [`v2.0.105`](https://redirect.github.com/dtolnay/syn/releases/tag/2.0.105) [Compare Source](https://redirect.github.com/dtolnay/syn/compare/2.0.104...2.0.105) - Disallow "negative" inherent impls like `impl !T {}` ([#1881](https://redirect.github.com/dtolnay/syn/issues/1881), [rust-lang/rust#144386](https://redirect.github.com/rust-lang/rust/pull/144386)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - "before 4am on Monday" (UTC), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR was generated by [Mend Renovate](https://mend.io/renovate/). View the [repository job log](https://developer.mend.io/github/astral-sh/uv).  Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

rustbot assigned compiler-errors Apr 15, 2025

oli-obk commented Apr 15, 2025

View reviewed changes

compiler/rustc_ast/src/ast.rs Outdated Show resolved Hide resolved

oli-obk force-pushed the new-const-traits-syntax branch from f6be056 to 2003458 Compare April 15, 2025 09:04