Remove suspicious auto trait lint

compiler/rustc_hir_analysis/src/coherence/orphan.rs

@@ -1,20 +1,12 @@
 //! Orphan checker: every impl either implements a trait defined in this
 //! crate or pertains to a type defined in this crate.
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::ErrorGuaranteed;
-use rustc_errors::{DelayDm, ErrorGuaranteed};
 use rustc_hir as hir;
-use rustc_middle::ty::util::CheckRegions;
+use rustc_middle::ty::{self, AliasKind, Ty, TyCtxt, TypeVisitableExt};
-use rustc_middle::ty::GenericArgs;
+use rustc_span::def_id::LocalDefId;
-use rustc_middle::ty::{
-    self, AliasKind, ImplPolarity, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
-    TypeVisitor,
-};
-use rustc_session::lint;
-use rustc_span::def_id::{DefId, LocalDefId};
 use rustc_span::Span;
 use rustc_trait_selection::traits;
-use std::ops::ControlFlow;
 
 use crate::errors;
 
@@ -26,12 +18,7 @@ pub(crate) fn orphan_check_impl(
     let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity();
     trait_ref.error_reported()?;
 
-    let ret = do_orphan_check_impl(tcx, trait_ref, impl_def_id);
+    do_orphan_check_impl(tcx, trait_ref, impl_def_id)
-    if tcx.trait_is_auto(trait_ref.def_id) {
-        lint_auto_trait_impl(tcx, trait_ref, impl_def_id);
-    }
-
-    ret
 }
 
 fn do_orphan_check_impl<'tcx>(
@@ -445,146 +432,3 @@ fn emit_orphan_check_error<'tcx>(
         }
     })
 }
-
-/// Lint impls of auto traits if they are likely to have
-/// unsound or surprising effects on auto impls.
-fn lint_auto_trait_impl<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    trait_ref: ty::TraitRef<'tcx>,
-    impl_def_id: LocalDefId,
-) {
-    if trait_ref.args.len() != 1 {
-        tcx.dcx().span_delayed_bug(
-            tcx.def_span(impl_def_id),
-            "auto traits cannot have generic parameters",
-        );
-        return;
-    }
-    let self_ty = trait_ref.self_ty();
-    let (self_type_did, args) = match self_ty.kind() {
-        ty::Adt(def, args) => (def.did(), args),
-        _ => {
-            // FIXME: should also lint for stuff like `&i32` but
-            // considering that auto traits are unstable, that
-            // isn't too important for now as this only affects
-            // crates using `nightly`, and std.
-            return;
-        }
-    };
-
-    // Impls which completely cover a given root type are fine as they
-    // disable auto impls entirely. So only lint if the args
-    // are not a permutation of the identity args.
-    let Err(arg) = tcx.uses_unique_generic_params(args, CheckRegions::No) else {
-        // ok
-        return;
-    };
-
-    // Ideally:
-    //
-    // - compute the requirements for the auto impl candidate
-    // - check whether these are implied by the non covering impls
-    // - if not, emit the lint
-    //
-    // What we do here is a bit simpler:
-    //
-    // - badly check if an auto impl candidate definitely does not apply
-    //   for the given simplified type
-    // - if so, do not lint
-    if fast_reject_auto_impl(tcx, trait_ref.def_id, self_ty) {
-        // ok
-        return;
-    }
-
-    tcx.node_span_lint(
-        lint::builtin::SUSPICIOUS_AUTO_TRAIT_IMPLS,
-        tcx.local_def_id_to_hir_id(impl_def_id),
-        tcx.def_span(impl_def_id),
-        DelayDm(|| {
-            format!(
-                "cross-crate traits with a default impl, like `{}`, \
-                         should not be specialized",
-                tcx.def_path_str(trait_ref.def_id),
-            )
-        }),
-        |lint| {
-            let item_span = tcx.def_span(self_type_did);
-            let self_descr = tcx.def_descr(self_type_did);
-            match arg {
-                ty::util::NotUniqueParam::DuplicateParam(arg) => {
-                    lint.note(format!("`{arg}` is mentioned multiple times"));
-                }
-                ty::util::NotUniqueParam::NotParam(arg) => {
-                    lint.note(format!("`{arg}` is not a generic parameter"));
-                }
-            }
-            lint.span_note(
-                item_span,
-                format!(
-                    "try using the same sequence of generic parameters as the {self_descr} definition",
-                ),
-            );
-        },
-    );
-}
-
-fn fast_reject_auto_impl<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId, self_ty: Ty<'tcx>) -> bool {
-    struct DisableAutoTraitVisitor<'tcx> {
-        tcx: TyCtxt<'tcx>,
-        trait_def_id: DefId,
-        self_ty_root: Ty<'tcx>,
-        seen: FxHashSet<DefId>,
-    }
-
-    impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for DisableAutoTraitVisitor<'tcx> {
-        type BreakTy = ();
-        fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
-            let tcx = self.tcx;
-            if ty != self.self_ty_root {
-                for impl_def_id in tcx.non_blanket_impls_for_ty(self.trait_def_id, ty) {
-                    match tcx.impl_polarity(impl_def_id) {
-                        ImplPolarity::Negative => return ControlFlow::Break(()),
-                        ImplPolarity::Reservation => {}
-                        // FIXME(@lcnr): That's probably not good enough, idk
-                        //
-                        // We might just want to take the rustdoc code and somehow avoid
-                        // explicit impls for `Self`.
-                        ImplPolarity::Positive => return ControlFlow::Continue(()),
-                    }
-                }
-            }
-
-            match ty.kind() {
-                ty::Adt(def, args) if def.is_phantom_data() => args.visit_with(self),
-                ty::Adt(def, args) => {
-                    // @lcnr: This is the only place where cycles can happen. We avoid this
-                    // by only visiting each `DefId` once.
-                    //
-                    // This will be is incorrect in subtle cases, but I don't care :)
-                    if self.seen.insert(def.did()) {
-                        for ty in def.all_fields().map(|field| field.ty(tcx, args)) {
-                            ty.visit_with(self)?;
-                        }
-                    }
-
-                    ControlFlow::Continue(())
-                }
-                _ => ty.super_visit_with(self),
-            }
-        }
-    }
-
-    let self_ty_root = match self_ty.kind() {
-        ty::Adt(def, _) => Ty::new_adt(tcx, *def, GenericArgs::identity_for_item(tcx, def.did())),
-        _ => unimplemented!("unexpected self ty {:?}", self_ty),
-    };
-
-    self_ty_root
-        .visit_with(&mut DisableAutoTraitVisitor {
-            tcx,
-            self_ty_root,
-            trait_def_id,
-            seen: FxHashSet::default(),
-        })
-        .is_break()
-}

compiler/rustc_lint/src/lib.rs

@@ -524,6 +524,11 @@ fn register_builtins(store: &mut LintStore) {
         "no longer needed, see RFC #3535 \
          <https://rust-lang.github.io/rfcs/3535-constants-in-patterns.html> for more information",
     );
+    store.register_removed(
+        "suspicious_auto_trait_impls",
+        "no longer needed, see #93367 \
+         <https://github.com/rust-lang/rust/issues/93367> for more information",
+    );
 }
 
 fn register_internals(store: &mut LintStore) {

compiler/rustc_lint_defs/src/builtin.rs

@@ -90,7 +90,6 @@ declare_lint_pass! {
         SOFT_UNSTABLE,
         STABLE_FEATURES,
         STATIC_MUT_REFS,
-        SUSPICIOUS_AUTO_TRAIT_IMPLS,
         TEST_UNSTABLE_LINT,
         TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
         TRIVIAL_CASTS,
@@ -4032,40 +4031,6 @@ declare_lint! {
     "duplicated attribute"
 }
 
-declare_lint! {
-    /// The `suspicious_auto_trait_impls` lint checks for potentially incorrect
-    /// implementations of auto traits.
-    ///
-    /// ### Example
-    ///
-    /// ```rust
-    /// struct Foo<T>(T);
-    ///
-    /// unsafe impl<T> Send for Foo<*const T> {}
-    /// ```
-    ///
-    /// {{produces}}
-    ///
-    /// ### Explanation
-    ///
-    /// A type can implement auto traits, e.g. `Send`, `Sync` and `Unpin`,
-    /// in two different ways: either by writing an explicit impl or if
-    /// all fields of the type implement that auto trait.
-    ///
-    /// The compiler disables the automatic implementation if an explicit one
-    /// exists for given type constructor. The exact rules governing this
-    /// were previously unsound, quite subtle, and have been recently modified.
-    /// This change caused the automatic implementation to be disabled in more
-    /// cases, potentially breaking some code.
-    pub SUSPICIOUS_AUTO_TRAIT_IMPLS,
-    Warn,
-    "the rules governing auto traits have recently changed resulting in potential breakage",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
-        reference: "issue #93367 <https://github.com/rust-lang/rust/issues/93367>",
-    };
-}
-
 declare_lint! {
     /// The `deprecated_where_clause_location` lint detects when a where clause in front of the equals
     /// in an associated type.

src/tools/clippy/tests/ui/non_send_fields_in_send_ty.rs

@@ -1,5 +1,4 @@
 #![warn(clippy::non_send_fields_in_send_ty)]
-#![allow(suspicious_auto_trait_impls)]
 #![feature(extern_types)]
 
 use std::cell::UnsafeCell;

src/tools/clippy/tests/ui/non_send_fields_in_send_ty.stderr

@@ -1,11 +1,11 @@
 error: some fields in `RingBuffer<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:17:1
+  --> $DIR/non_send_fields_in_send_ty.rs:16:1
    |
 LL | unsafe impl<T> Send for RingBuffer<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `data` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:12:5
+  --> $DIR/non_send_fields_in_send_ty.rs:11:5
    |
 LL |     data: Vec<UnsafeCell<T>>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -14,155 +14,155 @@ LL |     data: Vec<UnsafeCell<T>>,
    = help: to override `-D warnings` add `#[allow(clippy::non_send_fields_in_send_ty)]`
 
 error: some fields in `MvccRwLock<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:26:1
+  --> $DIR/non_send_fields_in_send_ty.rs:25:1
    |
 LL | unsafe impl<T> Send for MvccRwLock<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `lock` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:23:5
+  --> $DIR/non_send_fields_in_send_ty.rs:22:5
    |
 LL |     lock: Mutex<Box<T>>,
    |     ^^^^^^^^^^^^^^^^^^^
    = help: add bounds on type parameter `T` that satisfy `Mutex<Box<T>>: Send`
 
 error: some fields in `ArcGuard<RC, T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:35:1
+  --> $DIR/non_send_fields_in_send_ty.rs:34:1
    |
 LL | unsafe impl<RC, T: Send> Send for ArcGuard<RC, T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `head` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:32:5
+  --> $DIR/non_send_fields_in_send_ty.rs:31:5
    |
 LL |     head: Arc<RC>,
    |     ^^^^^^^^^^^^^
    = help: add bounds on type parameter `RC` that satisfy `Arc<RC>: Send`
 
 error: some fields in `DeviceHandle<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:52:1
+  --> $DIR/non_send_fields_in_send_ty.rs:51:1
    |
 LL | unsafe impl<T: UsbContext> Send for DeviceHandle<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `context` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:48:5
+  --> $DIR/non_send_fields_in_send_ty.rs:47:5
    |
 LL |     context: T,
    |     ^^^^^^^^^^
    = help: add `T: Send` bound in `Send` impl
 
 error: some fields in `NoGeneric` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:60:1
+  --> $DIR/non_send_fields_in_send_ty.rs:59:1
    |
 LL | unsafe impl Send for NoGeneric {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `rc_is_not_send` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:57:5
+  --> $DIR/non_send_fields_in_send_ty.rs:56:5
    |
 LL |     rc_is_not_send: Rc<String>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: use a thread-safe type that implements `Send`
 
 error: some fields in `MultiField<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:69:1
+  --> $DIR/non_send_fields_in_send_ty.rs:68:1
    |
 LL | unsafe impl<T> Send for MultiField<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `field1` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:64:5
+  --> $DIR/non_send_fields_in_send_ty.rs:63:5
    |
 LL |     field1: T,
    |     ^^^^^^^^^
    = help: add `T: Send` bound in `Send` impl
 note: it is not safe to send field `field2` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:65:5
+  --> $DIR/non_send_fields_in_send_ty.rs:64:5
    |
 LL |     field2: T,
    |     ^^^^^^^^^
    = help: add `T: Send` bound in `Send` impl
 note: it is not safe to send field `field3` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:66:5
+  --> $DIR/non_send_fields_in_send_ty.rs:65:5
    |
 LL |     field3: T,
    |     ^^^^^^^^^
    = help: add `T: Send` bound in `Send` impl
 
 error: some fields in `MyOption<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:77:1
+  --> $DIR/non_send_fields_in_send_ty.rs:76:1
    |
 LL | unsafe impl<T> Send for MyOption<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `0` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:73:12
+  --> $DIR/non_send_fields_in_send_ty.rs:72:12
    |
 LL |     MySome(T),
    |            ^
    = help: add `T: Send` bound in `Send` impl
 
 error: some fields in `MultiParam<A, B>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:90:1
+  --> $DIR/non_send_fields_in_send_ty.rs:89:1
    |
 LL | unsafe impl<A, B> Send for MultiParam<A, B> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `vec` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:87:5
+  --> $DIR/non_send_fields_in_send_ty.rs:86:5
    |
 LL |     vec: Vec<(A, B)>,
    |     ^^^^^^^^^^^^^^^^
    = help: add bounds on type parameters `A, B` that satisfy `Vec<(A, B)>: Send`
 
 error: some fields in `HeuristicTest` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:109:1
+  --> $DIR/non_send_fields_in_send_ty.rs:108:1
    |
 LL | unsafe impl Send for HeuristicTest {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `field4` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:104:5
+  --> $DIR/non_send_fields_in_send_ty.rs:103:5
    |
 LL |     field4: (*const NonSend, Rc<u8>),
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: use a thread-safe type that implements `Send`
 
 error: some fields in `AttrTest3<T>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:129:1
+  --> $DIR/non_send_fields_in_send_ty.rs:128:1
    |
 LL | unsafe impl<T> Send for AttrTest3<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `0` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:124:11
+  --> $DIR/non_send_fields_in_send_ty.rs:123:11
    |
 LL |     Enum2(T),
    |           ^
    = help: add `T: Send` bound in `Send` impl
 
 error: some fields in `Complex<P, u32>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:138:1
+  --> $DIR/non_send_fields_in_send_ty.rs:137:1
    |
 LL | unsafe impl<P> Send for Complex<P, u32> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `field1` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:134:5
+  --> $DIR/non_send_fields_in_send_ty.rs:133:5
    |
 LL |     field1: A,
    |     ^^^^^^^^^
    = help: add `P: Send` bound in `Send` impl
 
 error: some fields in `Complex<Q, MutexGuard<'static, bool>>` are not safe to be sent to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:142:1
+  --> $DIR/non_send_fields_in_send_ty.rs:141:1
    |
 LL | unsafe impl<Q: Send> Send for Complex<Q, MutexGuard<'static, bool>> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: it is not safe to send field `field2` to another thread
-  --> $DIR/non_send_fields_in_send_ty.rs:135:5
+  --> $DIR/non_send_fields_in_send_ty.rs:134:5
    |
 LL |     field2: B,
    |     ^^^^^^^^^

src/tools/rust-analyzer/crates/ide-db/src/generated/lints.rs

@@ -502,10 +502,6 @@ pub const DEFAULT_LINTS: &[Lint] = &[
         label: "stable_features",
         description: r##"stable features found in `#[feature]` directive"##,
     },
-    Lint {
-        label: "suspicious_auto_trait_impls",
-        description: r##"the rules governing auto traits have recently changed resulting in potential breakage"##,
-    },
     Lint {
         label: "suspicious_double_ref_op",
         description: r##"suspicious call of trait method on `&&T`"##,
@@ -778,7 +774,6 @@ pub const DEFAULT_LINT_GROUPS: &[LintGroup] = &[
             "repr_transparent_external_private_fields",
             "semicolon_in_expressions_from_macros",
             "soft_unstable",
-            "suspicious_auto_trait_impls",
             "uninhabited_static",
             "unstable_name_collisions",
             "unstable_syntax_pre_expansion",

tests/ui/auto-traits/issue-117789.rs

@@ -1,5 +1,3 @@
-#![deny(suspicious_auto_trait_impls)]
-
 auto trait Trait<P> {} //~ ERROR auto traits cannot have generic parameters
 //~^ ERROR auto traits are experimental and possibly buggy
 impl<P> Trait<P> for () {}

tests/ui/auto-traits/issue-117789.stderr

@@ -1,5 +1,5 @@
 error[E0567]: auto traits cannot have generic parameters
-  --> $DIR/issue-117789.rs:3:17
+  --> $DIR/issue-117789.rs:1:17
    |
 LL | auto trait Trait<P> {}
    |            -----^^^ help: remove the parameters
@@ -7,7 +7,7 @@ LL | auto trait Trait<P> {}
    |            auto trait cannot have generic parameters
 
 error[E0658]: auto traits are experimental and possibly buggy
-  --> $DIR/issue-117789.rs:3:1
+  --> $DIR/issue-117789.rs:1:1
    |
 LL | auto trait Trait<P> {}
    | ^^^^^^^^^^^^^^^^^^^^^^

tests/ui/auto-traits/issue-83857-ub.rs

@@ -1,4 +1,3 @@
-#![allow(suspicious_auto_trait_impls)]
 // Tests that we don't incorrectly allow overlap between a builtin auto trait
 // impl and a user written one. See #83857 for more details
 

tests/ui/auto-traits/issue-83857-ub.stderr

@@ -1,12 +1,12 @@
 error[E0277]: `Foo<T, U>` cannot be sent between threads safely
-  --> $DIR/issue-83857-ub.rs:22:38
+  --> $DIR/issue-83857-ub.rs:21:38
    |
 LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i32) {
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Foo<T, U>` cannot be sent between threads safely
    |
    = help: the trait `Send` is not implemented for `Foo<T, U>`, which is required by `Foo<T, U>: WithAssoc`
 note: required for `Foo<T, U>` to implement `WithAssoc`
-  --> $DIR/issue-83857-ub.rs:15:15
+  --> $DIR/issue-83857-ub.rs:14:15
    |
 LL | impl<T: Send> WithAssoc for T {
    |         ----  ^^^^^^^^^     ^
@@ -18,7 +18,7 @@ LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i
    |                                                                                +++++++++++++++++++++
 
 error[E0277]: `Foo<T, U>` cannot be sent between threads safely
-  --> $DIR/issue-83857-ub.rs:22:80
+  --> $DIR/issue-83857-ub.rs:21:80
    |
 LL |   fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i32) {
    |  ________________________________________________________________________________^
@@ -31,7 +31,7 @@ LL | | }
    |
    = help: the trait `Send` is not implemented for `Foo<T, U>`, which is required by `Foo<T, U>: WithAssoc`
 note: required for `Foo<T, U>` to implement `WithAssoc`
-  --> $DIR/issue-83857-ub.rs:15:15
+  --> $DIR/issue-83857-ub.rs:14:15
    |
 LL | impl<T: Send> WithAssoc for T {
    |         ----  ^^^^^^^^^     ^
@@ -43,7 +43,7 @@ LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i
    |                                                                                +++++++++++++++++++++
 
 error[E0277]: `Foo<T, U>` cannot be sent between threads safely
-  --> $DIR/issue-83857-ub.rs:25:11
+  --> $DIR/issue-83857-ub.rs:24:11
    |
 LL |     f(foo(v));
    |       --- ^ `Foo<T, U>` cannot be sent between threads safely
@@ -52,7 +52,7 @@ LL |     f(foo(v));
    |
    = help: the trait `Send` is not implemented for `Foo<T, U>`
 note: required by a bound in `foo`
-  --> $DIR/issue-83857-ub.rs:29:11
+  --> $DIR/issue-83857-ub.rs:28:11
    |
 LL | fn foo<T: Send>(x: T) -> <T as WithAssoc>::Output {
    |           ^^^^ required by this bound in `foo`

tests/ui/auto-traits/suspicious-impls-lint.rs

@@ -1,50 +0,0 @@
-#![deny(suspicious_auto_trait_impls)]
-
-use std::marker::PhantomData;
-
-struct MayImplementSendOk<T>(T);
-unsafe impl<T: Send> Send for MayImplementSendOk<T> {} // ok
-
-struct MayImplementSendErr<T>(T);
-unsafe impl<T: Send> Send for MayImplementSendErr<&T> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-struct ContainsNonSendDirect<T>(*const T);
-unsafe impl<T: Send> Send for ContainsNonSendDirect<&T> {} // ok
-
-struct ContainsPtr<T>(*const T);
-struct ContainsIndirectNonSend<T>(ContainsPtr<T>);
-unsafe impl<T: Send> Send for ContainsIndirectNonSend<&T> {} // ok
-
-struct ContainsVec<T>(Vec<T>);
-unsafe impl Send for ContainsVec<i32> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-struct TwoParams<T, U>(T, U);
-unsafe impl<T: Send, U: Send> Send for TwoParams<T, U> {} // ok
-
-struct TwoParamsFlipped<T, U>(T, U);
-unsafe impl<T: Send, U: Send> Send for TwoParamsFlipped<U, T> {} // ok
-
-struct TwoParamsSame<T, U>(T, U);
-unsafe impl<T: Send> Send for TwoParamsSame<T, T> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-pub struct WithPhantomDataNonSend<T, U>(PhantomData<*const T>, U);
-unsafe impl<T> Send for WithPhantomDataNonSend<T, i8> {} // ok
-
-pub struct WithPhantomDataSend<T, U>(PhantomData<T>, U);
-unsafe impl<T> Send for WithPhantomDataSend<*const T, i8> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-pub struct WithLifetime<'a, T>(&'a (), T);
-unsafe impl<T> Send for WithLifetime<'static, T> {} // ok
-unsafe impl<T> Sync for WithLifetime<'static, Vec<T>> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-fn main() {}

tests/ui/auto-traits/suspicious-impls-lint.stderr

@@ -1,82 +0,0 @@
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:9:1
-   |
-LL | unsafe impl<T: Send> Send for MayImplementSendErr<&T> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `&T` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-impls-lint.rs:8:1
-   |
-LL | struct MayImplementSendErr<T>(T);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: the lint level is defined here
-  --> $DIR/suspicious-impls-lint.rs:1:9
-   |
-LL | #![deny(suspicious_auto_trait_impls)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:21:1
-   |
-LL | unsafe impl Send for ContainsVec<i32> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `i32` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-impls-lint.rs:20:1
-   |
-LL | struct ContainsVec<T>(Vec<T>);
-   | ^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:32:1
-   |
-LL | unsafe impl<T: Send> Send for TwoParamsSame<T, T> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `T` is mentioned multiple times
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-impls-lint.rs:31:1
-   |
-LL | struct TwoParamsSame<T, U>(T, U);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:40:1
-   |
-LL | unsafe impl<T> Send for WithPhantomDataSend<*const T, i8> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `*const T` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-impls-lint.rs:39:1
-   |
-LL | pub struct WithPhantomDataSend<T, U>(PhantomData<T>, U);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Sync`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:46:1
-   |
-LL | unsafe impl<T> Sync for WithLifetime<'static, Vec<T>> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `Vec<T>` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-impls-lint.rs:44:1
-   |
-LL | pub struct WithLifetime<'a, T>(&'a (), T);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 5 previous errors
-

tests/ui/auto-traits/suspicious-negative-impls-lint.rs

@@ -1,21 +0,0 @@
-#![feature(negative_impls)]
-#![deny(suspicious_auto_trait_impls)]
-
-use std::marker::PhantomData;
-
-struct ContainsVec<T>(Vec<T>);
-impl !Send for ContainsVec<u32> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-pub struct WithPhantomDataSend<T, U>(PhantomData<T>, U);
-impl<T> !Send for WithPhantomDataSend<*const T, u8> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-pub struct WithLifetime<'a, T>(&'a (), T);
-impl<T> !Sync for WithLifetime<'static, Option<T>> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
-
-fn main() {}

tests/ui/auto-traits/suspicious-negative-impls-lint.stderr

@@ -1,52 +0,0 @@
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-negative-impls-lint.rs:7:1
-   |
-LL | impl !Send for ContainsVec<u32> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `u32` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-negative-impls-lint.rs:6:1
-   |
-LL | struct ContainsVec<T>(Vec<T>);
-   | ^^^^^^^^^^^^^^^^^^^^^
-note: the lint level is defined here
-  --> $DIR/suspicious-negative-impls-lint.rs:2:9
-   |
-LL | #![deny(suspicious_auto_trait_impls)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-negative-impls-lint.rs:12:1
-   |
-LL | impl<T> !Send for WithPhantomDataSend<*const T, u8> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `*const T` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-negative-impls-lint.rs:11:1
-   |
-LL | pub struct WithPhantomDataSend<T, U>(PhantomData<T>, U);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: cross-crate traits with a default impl, like `Sync`, should not be specialized
-  --> $DIR/suspicious-negative-impls-lint.rs:17:1
-   |
-LL | impl<T> !Sync for WithLifetime<'static, Option<T>> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `Option<T>` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/suspicious-negative-impls-lint.rs:16:1
-   |
-LL | pub struct WithLifetime<'a, T>(&'a (), T);
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 3 previous errors
-

tests/ui/coherence/coherence-conflicting-negative-trait-impl.rs

@@ -13,7 +13,5 @@ impl<T: MyTrait> !Send for TestType<T> {} //~ ERROR found both positive and nega
 unsafe impl<T: 'static> Send for TestType<T> {} //~ ERROR conflicting implementations
 
 impl !Send for TestType<i32> {}
-//~^ WARNING
-//~| WARNING this will change its meaning
 
 fn main() {}

tests/ui/coherence/coherence-conflicting-negative-trait-impl.stderr

@@ -16,23 +16,7 @@ LL | unsafe impl<T: MyTrait + 'static> Send for TestType<T> {}
 LL | unsafe impl<T: 'static> Send for TestType<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `TestType<_>`
 
-warning: cross-crate traits with a default impl, like `Send`, should not be specialized
+error: aborting due to 2 previous errors
-  --> $DIR/coherence-conflicting-negative-trait-impl.rs:15:1
-   |
-LL | impl !Send for TestType<i32> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `i32` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/coherence-conflicting-negative-trait-impl.rs:7:1
-   |
-LL | struct TestType<T>(::std::marker::PhantomData<T>);
-   | ^^^^^^^^^^^^^^^^^^
-   = note: `#[warn(suspicious_auto_trait_impls)]` on by default
-
-error: aborting due to 2 previous errors; 1 warning emitted
 
 Some errors have detailed explanations: E0119, E0751.
 For more information about an error, try `rustc --explain E0119`.

tests/ui/coherence/coherence-orphan.rs

@@ -18,7 +18,5 @@ impl TheTrait<isize> for TheType { }
 //~^ ERROR not all trait items implemented
 
 impl !Send for Vec<isize> {} //~ ERROR E0117
-//~^ WARNING
-//~| WARNING this will change its meaning
 
 fn main() {}

tests/ui/coherence/coherence-orphan.stderr

@@ -21,19 +21,6 @@ LL | impl !Send for Vec<isize> { }
    |
    = note: define and implement a trait or new type instead
 
-warning: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/coherence-orphan.rs:20:1
-   |
-LL | impl !Send for Vec<isize> { }
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `isize` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
-   = note: `#[warn(suspicious_auto_trait_impls)]` on by default
-
 error[E0046]: not all trait items implemented, missing: `the_fn`
   --> $DIR/coherence-orphan.rs:10:1
    |
@@ -58,7 +45,7 @@ LL | impl TheTrait<isize> for TheType { }
    |
    = help: implement the missing item: `fn the_fn(&self) { todo!() }`
 
-error: aborting due to 5 previous errors; 1 warning emitted
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0046, E0117.
 For more information about an error, try `rustc --explain E0046`.

tests/ui/coherence/coherence-overlap-negative-impls.rs

@@ -15,16 +15,20 @@ struct Test;
 
 trait Fold<F> {}
 
-impl<T, F> Fold<F> for Cons<T> // 0
+impl<T, F> Fold<F> for Cons<T>
+// 0
 where
     T: Fold<Nil>,
-{}
+{
+}
 
-impl<T, F> Fold<F> for Cons<T> // 1
+impl<T, F> Fold<F> for Cons<T>
+// 1
 where
     T: Fold<F>,
     private::Is<T>: private::NotNil,
-{}
+{
+}
 
 impl<F> Fold<F> for Test {} // 2
 
@@ -34,7 +38,6 @@ mod private {
     pub struct Is<T>(T);
     pub auto trait NotNil {}
 
-    #[allow(suspicious_auto_trait_impls)]
     impl !NotNil for Is<Nil> {}
 }
 

tests/ui/issues/issue-106755.rs

@@ -15,7 +15,5 @@ impl<T: MyTrait> !Send for TestType<T> {} //~ ERROR found both positive and nega
 unsafe impl<T: 'static> Send for TestType<T> {} //~ ERROR conflicting implementations
 
 impl !Send for TestType<i32> {}
-//~^ WARNING
-//~| WARNING this will change its meaning
 
 fn main() {}

tests/ui/issues/issue-106755.stderr

@@ -16,23 +16,7 @@ LL | unsafe impl<T: MyTrait + 'static> Send for TestType<T> {}
 LL | unsafe impl<T: 'static> Send for TestType<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `TestType<_>`
 
-warning: cross-crate traits with a default impl, like `Send`, should not be specialized
+error: aborting due to 2 previous errors
-  --> $DIR/issue-106755.rs:17:1
-   |
-LL | impl !Send for TestType<i32> {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #93367 <https://github.com/rust-lang/rust/issues/93367>
-   = note: `i32` is not a generic parameter
-note: try using the same sequence of generic parameters as the struct definition
-  --> $DIR/issue-106755.rs:9:1
-   |
-LL | struct TestType<T>(::std::marker::PhantomData<T>);
-   | ^^^^^^^^^^^^^^^^^^
-   = note: `#[warn(suspicious_auto_trait_impls)]` on by default
-
-error: aborting due to 2 previous errors; 1 warning emitted
 
 Some errors have detailed explanations: E0119, E0751.
 For more information about an error, try `rustc --explain E0119`.

tests/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.rs

@@ -1,5 +1,4 @@
 //@ aux-build:tdticc_coherence_lib.rs
-#![allow(suspicious_auto_trait_impls)]
 
 // Test that we do not consider associated types to be sendable without
 // some applicable trait bound (and we don't ICE).

tests/ui/typeck/typeck-default-trait-impl-cross-crate-coherence.stderr

@@ -1,5 +1,5 @@
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:14:1
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:13:1
    |
 LL | impl DefaultedTrait for (A,) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^----
@@ -10,7 +10,7 @@ LL | impl DefaultedTrait for (A,) { }
    = note: define and implement a trait or new type instead
 
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:17:1
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:16:1
    |
 LL | impl !DefaultedTrait for (B,) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^----
@@ -21,13 +21,13 @@ LL | impl !DefaultedTrait for (B,) { }
    = note: define and implement a trait or new type instead
 
 error[E0321]: cross-crate traits with a default impl, like `DefaultedTrait`, can only be implemented for a struct/enum type defined in the current crate
-  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:21:1
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:20:1
    |
 LL | impl DefaultedTrait for Box<C> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait for type in another crate
 
 error[E0117]: only traits defined in the current crate can be implemented for types defined outside of the crate
-  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:22:1
+  --> $DIR/typeck-default-trait-impl-cross-crate-coherence.rs:21:1
    |
 LL | impl DefaultedTrait for lib::Something<C> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^-----------------