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::{DiagnosticBuilder, 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;
@@ -496,36 +495,36 @@ fn lint_auto_trait_impl<'tcx>(
         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 `{}`, \
+    let msg = 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",
-                ),
-            );
-        },
+        tcx.def_path_str(trait_ref.def_id),
     );
+    let mut err: DiagnosticBuilder<'_, ()> =
+        DiagnosticBuilder::new(tcx.sess.dcx(), rustc_errors::Level::Error, msg);
+
+    let impl_span = tcx.def_span(impl_def_id);
+    err.span(impl_span);
+
+    match arg {
+        ty::util::NotUniqueParam::DuplicateParam(arg) => {
+            err.note(format!("`{arg}` is mentioned multiple times"));
+        }
+        ty::util::NotUniqueParam::NotParam(arg) => {
+            err.note(format!("`{arg}` is not a generic parameter"));
+        }
+    }
+
+    let self_span = tcx.def_span(self_type_did);
+    let self_descr = tcx.def_descr(self_type_did);
+    err.span_note(
+        self_span,
+        format!(
+            "try using the same sequence of generic parameters as the {self_descr} definition",
+        ),
+    );
+
+    err.emit();
 }
 
 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.

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
 
@@ -8,6 +7,7 @@ struct Foo<T, U>(Always<T, U>);
 
 trait False {}
 unsafe impl<U: False> Send for Foo<u32, U> {}
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 trait WithAssoc {
     type Output;

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

@@ -1,3 +1,16 @@
+error: cross-crate traits with a default impl, like `Send`, should not be specialized
+  --> $DIR/issue-83857-ub.rs:9:1
+   |
+LL | unsafe impl<U: False> Send for Foo<u32, U> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `u32` is not a generic parameter
+note: try using the same sequence of generic parameters as the struct definition
+  --> $DIR/issue-83857-ub.rs:6:1
+   |
+LL | struct Foo<T, U>(Always<T, U>);
+   | ^^^^^^^^^^^^^^^^
+
 error[E0277]: `Foo<T, U>` cannot be sent between threads safely
   --> $DIR/issue-83857-ub.rs:22:38
    |
@@ -17,6 +30,6 @@ help: consider introducing a `where` clause, but there might be an alternative b
 LL | fn generic<T, U>(v: Foo<T, U>, f: fn(<Foo<T, U> as WithAssoc>::Output) -> i32) where Foo<T, U>: Send {
    |                                                                                +++++++++++++++++++++
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.

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

@@ -1,14 +1,11 @@
-#![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
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 struct ContainsNonSendDirect<T>(*const T);
 unsafe impl<T: Send> Send for ContainsNonSendDirect<&T> {} // ok
@@ -19,8 +16,7 @@ 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
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 struct TwoParams<T, U>(T, U);
 unsafe impl<T: Send, U: Send> Send for TwoParams<T, U> {} // ok
@@ -30,21 +26,18 @@ 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
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 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
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 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
+//~^ ERROR cross-crate traits with a default impl, like `Sync`, should not be specialized
 
 fn main() {}

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

@@ -1,79 +1,64 @@
 error: cross-crate traits with a default impl, like `Send`, should not be specialized
-  --> $DIR/suspicious-impls-lint.rs:9:1
+  --> $DIR/suspicious-impls-lint.rs:7:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:6:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:18:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:17:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:28:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:27:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:35:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:34:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:40:1
    |
 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
+  --> $DIR/suspicious-impls-lint.rs:38:1
    |
 LL | pub struct WithLifetime<'a, T>(&'a (), T);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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

@@ -1,21 +1,17 @@
 #![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
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 pub struct WithPhantomDataSend<T, U>(PhantomData<T>, U);
 impl<T> !Send for WithPhantomDataSend<*const T, u8> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
+//~^ ERROR cross-crate traits with a default impl, like `Send`, should not be specialized
 
 pub struct WithLifetime<'a, T>(&'a (), T);
 impl<T> !Sync for WithLifetime<'static, Option<T>> {}
-//~^ ERROR
-//~| WARNING this will change its meaning
+//~^ ERROR cross-crate traits with a default impl, like `Sync`, should not be specialized
 
 fn main() {}