Remove suspicious auto trait lint

Author: spastorino

compiler/rustc_hir_analysis/src/coherence/orphan.rs

@@ -2,15 +2,14 @@
 //! crate or pertains to a type defined in this crate.
 
 use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{DelayDm, ErrorGuaranteed};
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_middle::ty::util::CheckRegions;
 use rustc_middle::ty::GenericArgs;
 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;
@@ -461,8 +460,8 @@ fn lint_auto_trait_impl<'tcx>(
         return;
     }
     let self_ty = trait_ref.self_ty();
-    let (self_type_did, args) = match self_ty.kind() {
-        ty::Adt(def, args) => (def.did(), args),
+    let args = match self_ty.kind() {
+        ty::Adt(_, args) => args,
         _ => {
             // FIXME: should also lint for stuff like `&i32` but
             // considering that auto traits are unstable, that
@@ -475,8 +474,7 @@ fn lint_auto_trait_impl<'tcx>(
     // 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
+    if tcx.uses_unique_generic_params(args, CheckRegions::No).is_ok() {
         return;
     };
 
@@ -495,37 +493,6 @@ fn lint_auto_trait_impl<'tcx>(
         // 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 {

compiler/rustc_lint_defs/src/builtin.rs

@@ -90,7 +90,6 @@ declare_lint_pass! {
         SOFT_UNSTABLE,
         STABLE_FEATURES,
         STATIC_MUT_REF,
-        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

@@ -1,13 +1,13 @@
 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
    |            |
    |            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