Fix trait method resolution on an adjusted never type by JonathanBrouwer · Pull Request #156047 · rust-lang/rust

JonathanBrouwer · 2026-05-01T14:22:44Z

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Fixes #143349

r? @WaffleLapkin
cc @lcnr

rustbot · 2026-05-01T14:22:49Z

WaffleLapkin is not on the review rotation at the moment.
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JonathanBrouwer · 2026-05-01T14:23:14Z

Note that this PR allows more code to compile on stable, for example see this test.

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If this is a problem we could delay the problem by putting this change behind the never_type feature gate

lcnr

I think this a reasonable change, I would expect us to emit a FCW here, I don't want to support this permanently or more importantly, this may overlap with other kinds of inference fallback in the future, so we generally don't want users to rely on this

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JonathanBrouwer · 2026-05-01T15:22:00Z

This PR is now based on #156048, still need to add the FCW lint, I'll do that later.
@rustbot author

Is "Trait method call on adjusted never type" the correct terminology? I'm not super familiar with the type system yet

rustbot · 2026-05-02T16:12:44Z

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

JonathanBrouwer · 2026-05-03T10:55:51Z

@rustbot ready

I rebased on #156079 and #156048 so the diff is nicely small now

Rollup of 6 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #156047 (Fix trait method resolution on an adjusted never type) - #159061 (Skip trivial cast lint for trait object upcasts) - #159241 (Update books) - #159248 (compiler: Remove `-Zmutable-noalias`) - #159250 (Rename `errors.rs` file to `diagnostics.rs` (13/N))

@WaffleLapkin

…=lcnr,wafflelapkin Fix trait method resolution on an adjusted never type Fixes rust-lang#143349 r? @WaffleLapkin cc @lcnr

Rollup of 6 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #156047 (Fix trait method resolution on an adjusted never type) - #158981 (Fix where-bound suggestion with legacy const generics) - #159061 (Skip trivial cast lint for trait object upcasts) - #159248 (compiler: Remove `-Zmutable-noalias`) - #159250 (Rename `errors.rs` file to `diagnostics.rs` (13/N))

jhpratt · 2026-07-14T04:15:01Z

@bors r- #159260 (comment)

Simple typo

rust-bors · 2026-07-14T04:15:08Z

This pull request was unapproved.

This PR was contained in a rollup (#159262), which was unapproved.

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ehuss · 2026-07-14T04:22:22Z

+    ///
+    /// ### Example
+    ///
+    /// ```rust,ignore (does not compile on stage1 until bootstrap, change this to no_run after bootstrap is updated, writing CURRENT_RUSTC_VERSION hoping this is noticed in the diff)


This isn't quite the correct way to do this for a new lint. I think it requires some combination of #[cfg_attr(bootstrap, doc = "```rust")] lines. See https://github.com/rust-lang/rust/pull/155521/changes#diff-c39514e6f2a747139246fae90b0fca9c3485b104d3a0a04aea11361918d2434fR20-R23 for an example.

(I don't love that the tests are run this way.)

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(I don't love that the tests are run this way.)

Do you mean that we still run ignore'ed tests? How does that happen?

I didn't even know you can cfg_attr doc comments, awesome! Will fix it

I tried looking for this on the rustc dev guide but couldn't find it, I'll also add a section for it :)

The ignore tests aren't run. The error message explains what is happening:

The documentation generator cannot generate the example output when the example is ignored.
Manually include the sample output below the example. For example:

It's the {{produces}} part that doesn't work with ignore (since there's no way for it to generate the output).

However, using ignore in this situation isn't the right thing. ignore should only be used in cases where it is impossible to exercise the lint with our current harness.

The reason you can't just have a normal rust example here is because there is a CI job that tries to run doctests with an older rustc. Personally I don't think that is worth trying to support that, but I understand it's not simple.

It's also just a bad interaction of using doc-comments for this purpose. The code examples are only intended to run with the lint-docs tool. I don't remember, but I don't think I ever intended them to run via doctests. I feel like something changed along the line, because this used to not be a problem.

One idea to try to work around this is to stop using doc-comments for this documentation. They cause several problems (like showing up in search engines). Perhaps either change them to regular comments, or move them to separate files (like the E code files).

ehuss · 2026-07-14T04:24:50Z

Simple typo

That's not the case here. There's no typo for the widnows thing. That error message is showing an example of a lint that deals with a typo. It is unrelated here, as the issue is that it should be using cfg_attr.

JonathanBrouwer · 2026-07-14T11:55:36Z

@bors try jobs=x86_64-gnu-llvm-22-3

Fix trait method resolution on an adjusted never type try-job: x86_64-gnu-llvm-22-3

rust-bors · 2026-07-14T13:55:59Z

☀️ Try build successful (CI)
Build commit: b84fe77 (b84fe77d754fd3febfc50e255f344a678189db2e)
Base parent: da80ed0 (da80ed0708a09dc096c184345d6eb42cbcd50a1e)

JonathanBrouwer · 2026-07-14T14:48:22Z

@bors r=lcnr,wafflelapkin

rust-bors · 2026-07-14T14:48:25Z

📌 Commit 62c7143 has been approved by lcnr,wafflelapkin

It is now in the queue for this repository.

…uwer Rollup of 22 pull requests Successful merges: - #156047 (Fix trait method resolution on an adjusted never type) - #157824 (Comptime inherent impls) - #158235 (Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known`) - #158723 (Support EII on Windows MSVC) - #158993 (rerun in original typing mode if we meet any opaques in post analysis) - #159160 (Make `HasTokens` a sub-trait of `HasAttrs`.) - #159183 (Introduce InstanceKind::LlvmIntrinsic) - #159251 (Bump rustc-perf submodule) - #155013 (Suggest the `[const] Destruct` bound for type parameters in const functions when missing) - #159155 (unstable book: Document `diagnostic_on_unknown` feature) - #159235 (Add regression test for #95719) - #159243 (inline Once wait and wait_force) - #159255 (Replace shortened type with `_` instead of `...` as placeholder) - #159259 (Add regression test for #144033) - #159265 (bootstrap: skip intrinsic-test when rustfmt is unavailable) - #159269 (disable range-len-try-from.rs on s390x) - #159272 (slice: make swap delegate to swap_unchecked) - #159274 (bootstrap: Rename `std_crates_for_run_make` to `std_crates_for_make_run`) - #159275 (remove obsolete comment) - #159277 (Construct `tokens` for attrs made by `mk_attr_word` and other variants) - #159283 (Remove obsolete verbose flag from deref/ref suggestions) - #159290 (rustc-dev-guide subtree update)

@WaffleLapkin

Rollup merge of #156047 - JonathanBrouwer:never-ty-method, r=lcnr,wafflelapkin Fix trait method resolution on an adjusted never type Fixes #143349 r? @WaffleLapkin cc @lcnr

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#156047 (Fix trait method resolution on an adjusted never type) - rust-lang/rust#157824 (Comptime inherent impls) - rust-lang/rust#158235 (Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known`) - rust-lang/rust#158723 (Support EII on Windows MSVC) - rust-lang/rust#158993 (rerun in original typing mode if we meet any opaques in post analysis) - rust-lang/rust#159160 (Make `HasTokens` a sub-trait of `HasAttrs`.) - rust-lang/rust#159183 (Introduce InstanceKind::LlvmIntrinsic) - rust-lang/rust#159251 (Bump rustc-perf submodule) - rust-lang/rust#155013 (Suggest the `[const] Destruct` bound for type parameters in const functions when missing) - rust-lang/rust#159155 (unstable book: Document `diagnostic_on_unknown` feature) - rust-lang/rust#159235 (Add regression test for rust-lang/rust#95719) - rust-lang/rust#159243 (inline Once wait and wait_force) - rust-lang/rust#159255 (Replace shortened type with `_` instead of `...` as placeholder) - rust-lang/rust#159259 (Add regression test for rust-lang/rust#144033) - rust-lang/rust#159265 (bootstrap: skip intrinsic-test when rustfmt is unavailable) - rust-lang/rust#159269 (disable range-len-try-from.rs on s390x) - rust-lang/rust#159272 (slice: make swap delegate to swap_unchecked) - rust-lang/rust#159274 (bootstrap: Rename `std_crates_for_run_make` to `std_crates_for_make_run`) - rust-lang/rust#159275 (remove obsolete comment) - rust-lang/rust#159277 (Construct `tokens` for attrs made by `mk_attr_word` and other variants) - rust-lang/rust#159283 (Remove obsolete verbose flag from deref/ref suggestions) - rust-lang/rust#159290 (rustc-dev-guide subtree update)

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Comment thread compiler/rustc_hir_typeck/src/method/probe.rs Outdated

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JonathanBrouwer force-pushed the never-ty-method branch from 75d6b9a to d72e38a Compare May 1, 2026 15:01

WaffleLapkin added needs-fcp This change is insta-stable, or significant enough to need a team FCP to proceed. T-types Relevant to the types team, which will review and decide on the PR/issue. labels May 1, 2026

JonathanBrouwer mentioned this pull request May 2, 2026

Move and rename the clone-never.rs test #156079

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Comment thread compiler/rustc_lint_defs/src/builtin.rs Outdated

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jhpratt mentioned this pull request Jul 14, 2026

Rollup of 6 pull requests #159260

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jhpratt added a commit to jhpratt/rust that referenced this pull request Jul 14, 2026

Rollup merge of rust-lang#156047 - JonathanBrouwer:never-ty-method, r…

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…=lcnr,wafflelapkin Fix trait method resolution on an adjusted never type Fixes rust-lang#143349 r? @WaffleLapkin cc @lcnr

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Rollup of 6 pull requests #159262

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ehuss mentioned this pull request Jul 14, 2026

Update books #159241

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Don't run doctest because it doesn't compile on stage1

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Auto merge of #156047 - JonathanBrouwer:never-ty-method, r=<try>

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Fix trait method resolution on an adjusted never type try-job: x86_64-gnu-llvm-22-3

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Rollup of 22 pull requests #159293

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Unrolled build for #156047

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Rollup merge of #156047 - JonathanBrouwer:never-ty-method, r=lcnr,wafflelapkin Fix trait method resolution on an adjusted never type Fixes #143349 r? @WaffleLapkin cc @lcnr

rustbot added this to the 1.99.0 milestone Jul 15, 2026

purplesyringa mentioned this pull request Jul 15, 2026

Inconsistent method lookup on never type #143349

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