parse const trait Trait

[fee1-dead]

r? oli-obk or anyone from project-const-traits

cc @rust-lang/project-const-traits

[rustbot]

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol, @tshepang

This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

HIR ty lowering was modified

cc @fmease

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

[rustbot]

This PR modifies run-make tests.

cc @jieyouxu

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[endgroup]
[TIMING] core::build_steps::tool::ToolBuild { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, tool: "tidy", path: "src/tools/tidy", mode: ToolBootstrap, source_type: InTree, extra_features: [], allow_features: "", cargo_args: [], artifact_kind: Binary } -- 9.470
[TIMING] core::build_steps::tool::Tidy { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
fmt check
Diff in /checkout/tests/run-make/const-trait-stable-toolchain/rmake.rs:11:
         .env("RUSTC_BOOTSTRAP", "-1")
         .cfg("feature_enabled")
         .run_fail()
-        .assert_stderr_not_contains(
-            "as `const` to allow it to have `const` implementations",
-        )
+        .assert_stderr_not_contains("as `const` to allow it to have `const` implementations")
         .stderr_utf8();
     diff()
         .expected_file("const-super-trait-stable-enabled.stderr")
Diff in /checkout/tests/run-make/const-trait-stable-toolchain/rmake.rs:40:
         .env("RUSTC_BOOTSTRAP", "-1")
         .run_fail()
         .assert_stderr_not_contains("enable `#![feature(const_trait_impl)]` in your crate and mark")
-        .assert_stderr_not_contains(
-            "as `const` to allow it to have `const` implementations",
-        )
+        .assert_stderr_not_contains("as `const` to allow it to have `const` implementations")
         .stderr_utf8();
     diff()
         .expected_file("const-super-trait-stable-disabled.stderr")
fmt: checked 6159 files
Build completed unsuccessfully in 0:00:44
  local time: Sun Jul 13 15:59:29 UTC 2025
  network time: Sun, 13 Jul 2025 15:59:29 GMT
##[error]Process completed with exit code 1.

[bors]

☔ The latest upstream changes (presumably #143888) made this pull request unmergeable. Please resolve the merge conflicts.

[fmease]

This doesn't admit const auto trait Trait {}, it should tho (it already allows const unsafe auto trait Trait {}). Ofc for that const auto needs to be followed by trait so we don't regress const auto: () = ();.

[fmease]

Looks good, thanks! r=me after rebase, fmt fix and with nits addressed.

[fmease]

I don't think this file should be modified? This will just fail in r-a's repo after the sync bc r-a doesn't impl the new syntax (we currently don't run r-a's tests in r-l/r's CI).