Emit the suspicious_auto_trait_impls for negative impls as well

compiler/rustc_hir_analysis/src/coherence/orphan.rs

@@ -478,10 +478,6 @@ fn lint_auto_trait_impl<'tcx>(
     trait_ref: ty::TraitRef<'tcx>,
     impl_def_id: LocalDefId,
 ) {
-    if tcx.impl_polarity(impl_def_id) != ImplPolarity::Positive {
-        return;
-    }
-
     assert_eq!(trait_ref.substs.len(), 1);
     let self_ty = trait_ref.self_ty();
     let (self_type_did, substs) = match self_ty.kind() {

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

@@ -0,0 +1,21 @@
+#![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

@@ -0,0 +1,52 @@
+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

@@ -13,5 +13,7 @@ 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

@@ -16,7 +16,23 @@ LL | unsafe impl<T: MyTrait + 'static> Send for TestType<T> {}
 LL | unsafe impl<T: 'static> Send for TestType<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `TestType<_>`
 
-error: aborting due to 2 previous errors
+warning: cross-crate traits with a default impl, like `Send`, should not be specialized
+  --> $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

@@ -14,7 +14,8 @@ impl TheTrait<TheType> for isize { }
 
 impl TheTrait<isize> for TheType { }
 
-impl !Send for Vec<isize> { }
-//~^ ERROR E0117
+impl !Send for Vec<isize> { } //~ ERROR E0117
+//~^ WARNING
+//~| WARNING this will change its meaning
 
 fn main() { }

tests/ui/coherence/coherence-orphan.stderr

@@ -21,6 +21,19 @@ LL | impl !Send for Vec<isize> { }
    |
    = note: define and implement a trait or new type instead
 
-error: aborting due to 2 previous errors
+warning: cross-crate traits with a default impl, like `Send`, should not be specialized
+  --> $DIR/coherence-orphan.rs:17:1
+   |
+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: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0117`.

tests/ui/issues/issue-106755.rs

@@ -15,5 +15,7 @@ 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

@@ -16,7 +16,23 @@ LL | unsafe impl<T: MyTrait + 'static> Send for TestType<T> {}
 LL | unsafe impl<T: 'static> Send for TestType<T> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `TestType<_>`
 
-error: aborting due to 2 previous errors
+warning: cross-crate traits with a default impl, like `Send`, should not be specialized
+  --> $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`.