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Don't special-case ! in stability checks anymore #162162

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Merged
rust-bors merged 2 commits into from
Sep 3, 2026
+28 −19
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Don't special-case ! in stability checks anymore #162162

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fa8bb67
ineffective_unstable_trait_impl: add tests for `fn(!)` & `fn(UnstableT)`
GrigorenkoPV Sep 1, 2026
3cc3682
Don't special-case `!` in stability checks
GrigorenkoPV Sep 1, 2026
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15 changes: 0 additions & 15 deletions compiler/rustc_passes/src/stability.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -932,28 +932,13 @@ impl<'tcx> Visitor<'tcx> for CheckTraitImplStable<'tcx> {
}

fn visit_ty(&mut self, t: &'tcx Ty<'tcx, AmbigArg>) {
if let TyKind::Never = t.kind {
self.fully_stable = false;
}
if let TyKind::FnPtr(function) = t.kind {
if extern_abi_stability(function.abi).is_err() {
self.fully_stable = false;
}
}
intravisit::walk_ty(self, t)
}

fn visit_fn_decl(&mut self, fd: &'tcx hir::FnDecl<'tcx>) {
for ty in fd.inputs {
self.visit_ty_unambig(ty)
}
if let hir::FnRetTy::Return(output_ty) = fd.output {
match output_ty.kind {
TyKind::Never => {} // `-> !` is stable
_ => self.visit_ty_unambig(output_ty),
}
}
}
}

/// Given the list of enabled features that were not language features (i.e., that
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8 changes: 8 additions & 0 deletions tests/ui/stability-attribute/stability-attribute-trait-impl.rs
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Expand Up @@ -23,6 +23,7 @@ impl StableTrait for UnstableType {}
impl UnstableTrait for StableType {}

#[unstable(feature = "h", issue = "none")]
//~^ ERROR an `#[unstable]` annotation here has no effect [ineffective_unstable_trait_impl]
impl StableTrait for ! {}

// Note: If rust_cold_cc is stabilized, switch this to another (unstable) ABI.
Expand All @@ -40,4 +41,11 @@ impl StableTrait for fn() -> ! {}
#[unstable(feature = "l", issue = "none")]
impl StableTrait for fn() -> UnstableType {}

#[unstable(feature = "m", issue = "none")]
//~^ ERROR an `#[unstable]` annotation here has no effect [ineffective_unstable_trait_impl]
impl StableTrait for fn(!) {}

#[unstable(feature = "n", issue = "none")]
impl StableTrait for fn(UnstableType) {}

fn main() {}
24 changes: 20 additions & 4 deletions tests/ui/stability-attribute/stability-attribute-trait-impl.stderr
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Original file line number Diff line number Diff line change
@@ -1,20 +1,36 @@
error: an `#[unstable]` annotation here has no effect
--> $DIR/stability-attribute-trait-impl.rs:32:1
--> $DIR/stability-attribute-trait-impl.rs:25:1
|
LL | #[unstable(feature = "j", issue = "none")]
LL | #[unstable(feature = "h", issue = "none")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information
= note: `#[deny(ineffective_unstable_trait_impl)]` on by default

error: an `#[unstable]` annotation here has no effect
--> $DIR/stability-attribute-trait-impl.rs:36:1
--> $DIR/stability-attribute-trait-impl.rs:33:1
|
LL | #[unstable(feature = "j", issue = "none")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information

error: an `#[unstable]` annotation here has no effect
--> $DIR/stability-attribute-trait-impl.rs:37:1
|
LL | #[unstable(feature = "k", issue = "none")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information

error: an `#[unstable]` annotation here has no effect
--> $DIR/stability-attribute-trait-impl.rs:44:1
|
LL | #[unstable(feature = "m", issue = "none")]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information

error: module has missing stability attribute
--> $DIR/stability-attribute-trait-impl.rs:1:1
|
Expand All @@ -26,5 +42,5 @@ LL | | #[stable(feature = "a", since = "3.3.3")]
LL | | fn main() {}
| |____________^

error: aborting due to 3 previous errors
error: aborting due to 5 previous errors

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