introduce negative_impls feature gate and document

They used to be covered by `optin_builtin_traits` but negative impls
are now applicable to all traits, not just auto traits.

This also adds docs in the unstable book for the current state of auto traits.

src/test/pretty/trait-polarity.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // pp-exact
 

src/test/rustdoc/empty-section.rs

@@ -1,6 +1,6 @@
 #![crate_name = "foo"]
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 pub struct Foo;
 

src/test/rustdoc/impl-parts-crosscrate.rs

@@ -1,7 +1,7 @@
 // aux-build:rustdoc-impl-parts-crosscrate.rs
 // ignore-cross-compile
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 extern crate rustdoc_impl_parts_crosscrate;
 

src/test/rustdoc/impl-parts.rs

@@ -1,3 +1,4 @@
+#![feature(negative_impls)]
 #![feature(optin_builtin_traits)]
 
 pub auto trait AnOibit {}

src/test/rustdoc/issue-55321.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // @has issue_55321/struct.A.html
 // @has - '//*[@id="implementations-list"]/*[@class="impl"]//code' "impl !Send for A"

src/test/rustdoc/negative-impl-sidebar.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![crate_name = "foo"]
 
 pub struct Foo;

src/test/rustdoc/negative-impl.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // @matches negative_impl/struct.Alpha.html '//pre' "pub struct Alpha"
 pub struct Alpha;

src/test/ui/async-await/issue-64130-1-sync.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 // edition:2018
 
 // This tests the the specialized async-await-specific error when futures don't implement an

src/test/ui/async-await/issue-64130-2-send.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 // edition:2018
 
 // This tests the the specialized async-await-specific error when futures don't implement an

src/test/ui/async-await/issue-64130-3-other.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 // edition:2018
 
 // This tests the the unspecialized async-await-specific error when futures don't implement an

src/test/ui/async-await/issue-64130-3-other.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `Foo: Qux` is not satisfied in `impl std::future::Future`
-  --> $DIR/issue-64130-3-other.rs:23:5
+  --> $DIR/issue-64130-3-other.rs:24:5
    |
 LL | fn is_qux<T: Qux>(t: T) { }
    |    ------    --- required by this bound in `is_qux`
@@ -13,7 +13,7 @@ LL |     is_qux(bar());
    = help: the following implementations were found:
              <Foo as Qux>
 note: future does not implement `Qux` as this value is used across an await
-  --> $DIR/issue-64130-3-other.rs:17:5
+  --> $DIR/issue-64130-3-other.rs:18:5
    |
 LL |     let x = Foo;
    |         - has type `Foo`

src/test/ui/codemap_tests/empty_span.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 fn main() {
     struct Foo;
 

src/test/ui/coherence/coherence-conflicting-negative-trait-impl.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(marker_trait_attr)]
 
 #[marker]

src/test/ui/coherence/coherence-default-trait-impl.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait MySafeTrait {}
 

src/test/ui/coherence/coherence-default-trait-impl.stderr

@@ -1,11 +1,11 @@
 error[E0199]: implementing the trait `MySafeTrait` is not unsafe
-  --> $DIR/coherence-default-trait-impl.rs:7:1
+  --> $DIR/coherence-default-trait-impl.rs:8:1
    |
 LL | unsafe impl MySafeTrait for Foo {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0200]: the trait `MyUnsafeTrait` requires an `unsafe impl` declaration
-  --> $DIR/coherence-default-trait-impl.rs:12:1
+  --> $DIR/coherence-default-trait-impl.rs:13:1
    |
 LL | impl MyUnsafeTrait for Foo {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // Test for issue #56934 - that it is impossible to redundantly
 // implement an auto-trait for a trait object type that contains it.

src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr

@@ -1,17 +1,17 @@
 error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
-  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:14:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:15:1
    |
 LL | impl !Marker1 for dyn Object + Marker2 { }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
 
 error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker2`
-  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:16:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:17:1
    |
 LL | impl !Marker2 for dyn Object + Marker2 { }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
 
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:22:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:23:1
    |
 LL | impl !Send for dyn Marker2 {}
    | ^^^^^^^^^^^^^^^-----------
@@ -22,13 +22,13 @@ LL | impl !Send for dyn Marker2 {}
    = note: define and implement a trait or new type instead
 
 error[E0321]: cross-crate traits with a default impl, like `std::marker::Send`, can only be implemented for a struct/enum type, not `(dyn Object + 'static)`
-  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:26:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:27:1
    |
 LL | impl !Send for dyn Object {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
 error[E0321]: cross-crate traits with a default impl, like `std::marker::Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker2 + 'static)`
-  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:27:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-negative.rs:28:1
    |
 LL | impl !Send for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type

src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // Test for issue #56934 - that it is impossible to redundantly
 // implement an auto-trait for a trait object type that contains it.

src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr

@@ -1,17 +1,17 @@
 error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
-  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:14:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:15:1
    |
 LL | impl Marker1 for dyn Object + Marker2 { }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker1`
 
 error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker2`
-  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:16:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:17:1
    |
 LL | impl Marker2 for dyn Object + Marker2 { }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
 
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:22:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:23:1
    |
 LL | unsafe impl Send for dyn Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^-----------
@@ -22,13 +22,13 @@ LL | unsafe impl Send for dyn Marker2 {}
    = note: define and implement a trait or new type instead
 
 error[E0321]: cross-crate traits with a default impl, like `std::marker::Send`, can only be implemented for a struct/enum type, not `(dyn Object + 'static)`
-  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:26:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:27:1
    |
 LL | unsafe impl Send for dyn Object {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
 error[E0321]: cross-crate traits with a default impl, like `std::marker::Send`, can only be implemented for a struct/enum type, not `(dyn Object + Marker2 + 'static)`
-  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:27:1
+  --> $DIR/coherence-impl-trait-for-marker-trait-positive.rs:28:1
    |
 LL | unsafe impl Send for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type

src/test/ui/coherence/coherence-impls-copy.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Copy;
 

src/test/ui/coherence/coherence-impls-send.rs

@@ -1,9 +1,9 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Copy;
 
 enum TestE {
-  A
+    A,
 }
 
 struct MyType;
@@ -26,5 +26,4 @@ unsafe impl Send for &'static [NotSync] {}
 //~^ ERROR conflicting implementations of trait
 //~| ERROR only traits defined in the current crate
 
-fn main() {
-}
+fn main() {}

src/test/ui/coherence/coherence-impls-sized.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Copy;
 

src/test/ui/coherence/coherence-negative-impls-safe-rpass.rs

@@ -2,7 +2,7 @@
 #![allow(dead_code)]
 // pretty-expanded FIXME #23616
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/coherence/coherence-negative-impls-safe.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/coherence/coherence-orphan.rs

@@ -1,5 +1,5 @@
 // aux-build:coherence_orphan_lib.rs
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 extern crate coherence_orphan_lib as lib;
 

src/test/ui/error-codes/E0198.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 struct Foo;
 

src/test/ui/error-codes/E0199.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 struct Foo;
 

src/test/ui/feature-gate-negative_impls.rs

@@ -0,0 +1,3 @@
+trait MyTrait {}
+impl !MyTrait for u32 {} //~ ERROR negative trait bounds are not yet fully implemented
+fn main() {}

src/test/ui/feature-gate-negative_impls.stderr

@@ -0,0 +1,12 @@
+error[E0658]: negative trait bounds are not yet fully implemented; use marker types for now
+  --> $DIR/feature-gate-negative_impls.rs:2:6
+   |
+LL | impl !MyTrait for u32 {}
+   |      ^^^^^^^^
+   |
+   = note: see issue #13231 <https://github.com/rust-lang/rust/issues/13231> for more information
+   = help: add `#![feature(negative_impls)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/feature-gates/feature-gate-optin-builtin-traits.stderr

@@ -14,7 +14,7 @@ LL | impl !AutoDummyTrait for DummyStruct {}
    |      ^^^^^^^^^^^^^^^
    |
    = note: see issue #13231 <https://github.com/rust-lang/rust/issues/13231> for more information
-   = help: add `#![feature(optin_builtin_traits)]` to the crate attributes to enable
+   = help: add `#![feature(negative_impls)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 

src/test/ui/generator/auto-trait-regions.nll.stderr

@@ -1,5 +1,5 @@
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/auto-trait-regions.rs:45:24
+  --> $DIR/auto-trait-regions.rs:46:24
    |
 LL |         let a = A(&mut true, &mut true, No);
    |                        ^^^^                - temporary value is freed at the end of this statement
@@ -12,7 +12,7 @@ LL |         assert_foo(a);
    = note: consider using a `let` binding to create a longer lived value
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/auto-trait-regions.rs:45:35
+  --> $DIR/auto-trait-regions.rs:46:35
    |
 LL |         let a = A(&mut true, &mut true, No);
    |                                   ^^^^     - temporary value is freed at the end of this statement
@@ -25,13 +25,13 @@ LL |         assert_foo(a);
    = note: consider using a `let` binding to create a longer lived value
 
 error: higher-ranked subtype error
-  --> $DIR/auto-trait-regions.rs:30:5
+  --> $DIR/auto-trait-regions.rs:31:5
    |
 LL |     assert_foo(gen);
    |     ^^^^^^^^^^^^^^^
 
 error: higher-ranked subtype error
-  --> $DIR/auto-trait-regions.rs:49:5
+  --> $DIR/auto-trait-regions.rs:50:5
    |
 LL |     assert_foo(gen);
    |     ^^^^^^^^^^^^^^^

src/test/ui/generator/auto-trait-regions.rs

@@ -1,5 +1,6 @@
 #![feature(generators)]
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Foo {}
 

src/test/ui/generator/auto-trait-regions.stderr

@@ -1,5 +1,5 @@
 error: implementation of `Foo` is not general enough
-  --> $DIR/auto-trait-regions.rs:30:5
+  --> $DIR/auto-trait-regions.rs:31:5
    |
 LL | auto trait Foo {}
    | ----------------- trait `Foo` defined here
@@ -11,7 +11,7 @@ LL |     assert_foo(gen);
    = note: ...but `Foo` is actually implemented for the type `&'1 OnlyFooIfStaticRef`, for some specific lifetime `'1`
 
 error: implementation of `Foo` is not general enough
-  --> $DIR/auto-trait-regions.rs:30:5
+  --> $DIR/auto-trait-regions.rs:31:5
    |
 LL | auto trait Foo {}
    | ----------------- trait `Foo` defined here
@@ -23,7 +23,7 @@ LL |     assert_foo(gen);
    = note: ...but `Foo` is actually implemented for the type `&'1 OnlyFooIfStaticRef`, for some specific lifetime `'1`
 
 error: implementation of `Foo` is not general enough
-  --> $DIR/auto-trait-regions.rs:49:5
+  --> $DIR/auto-trait-regions.rs:50:5
    |
 LL | auto trait Foo {}
    | ----------------- trait `Foo` defined here
@@ -35,7 +35,7 @@ LL |     assert_foo(gen);
    = note: ...but `Foo` is actually implemented for the type `A<'_, '2>`, for some specific lifetime `'2`
 
 error: implementation of `Foo` is not general enough
-  --> $DIR/auto-trait-regions.rs:49:5
+  --> $DIR/auto-trait-regions.rs:50:5
    |
 LL | auto trait Foo {}
    | ----------------- trait `Foo` defined here

src/test/ui/issues/issue-17718-static-sync.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Sync;
 

src/test/ui/issues/issue-23080-2.rs

@@ -1,6 +1,7 @@
 //~ ERROR
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 unsafe auto trait Trait {
     type Output; //~ ERROR E0380

src/test/ui/issues/issue-23080-2.stderr

@@ -1,5 +1,5 @@
 error[E0380]: auto traits cannot have methods or associated items
-  --> $DIR/issue-23080-2.rs:6:10
+  --> $DIR/issue-23080-2.rs:7:10
    |
 LL | unsafe auto trait Trait {
    |                   ----- auto trait cannot have items

src/test/ui/issues/issue-23080.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 unsafe auto trait Trait {
     fn method(&self) { //~ ERROR E0380

src/test/ui/issues/issue-23080.stderr

@@ -1,5 +1,5 @@
 error[E0380]: auto traits cannot have methods or associated items
-  --> $DIR/issue-23080.rs:4:8
+  --> $DIR/issue-23080.rs:5:8
    |
 LL | unsafe auto trait Trait {
    |                   ----- auto trait cannot have items

src/test/ui/issues/issue-29516.rs

@@ -1,5 +1,6 @@
 // check-pass
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait NotSame {}
 

src/test/ui/issues/issue-33140-hack-boundaries.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![allow(order_dependent_trait_objects)]
 
 // Check that the issue #33140 hack does not allow unintended things.

src/test/ui/mut/mutable-enum-indirect.rs

@@ -1,7 +1,7 @@
 // Tests that an `&` pointer to something inherently mutable is itself
 // to be considered mutable.
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Sync;
 

src/test/ui/never_type/auto-traits.rs

@@ -1,6 +1,7 @@
 // check-pass
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(never_type)]
 
 fn main() {

src/test/ui/no_send-enum.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/no_send-struct.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/no_share-enum.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Sync;
 

src/test/ui/no_share-struct.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Sync;
 

src/test/ui/parser/trait-object-bad-parens.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![allow(bare_trait_objects)]
 
 auto trait Auto {}

src/test/ui/parser/trait-object-bad-parens.stderr

@@ -1,23 +1,23 @@
 error[E0178]: expected a path on the left-hand side of `+`, not `((Auto))`
-  --> $DIR/trait-object-bad-parens.rs:7:16
+  --> $DIR/trait-object-bad-parens.rs:8:16
    |
 LL |     let _: Box<((Auto)) + Auto>;
    |                ^^^^^^^^^^^^^^^ expected a path
 
 error[E0178]: expected a path on the left-hand side of `+`, not `(Auto + Auto)`
-  --> $DIR/trait-object-bad-parens.rs:9:16
+  --> $DIR/trait-object-bad-parens.rs:10:16
    |
 LL |     let _: Box<(Auto + Auto) + Auto>;
    |                ^^^^^^^^^^^^^^^^^^^^ expected a path
 
 error[E0178]: expected a path on the left-hand side of `+`, not `(Auto)`
-  --> $DIR/trait-object-bad-parens.rs:11:16
+  --> $DIR/trait-object-bad-parens.rs:12:16
    |
 LL |     let _: Box<(Auto +) + Auto>;
    |                ^^^^^^^^^^^^^^^ expected a path
 
 error[E0178]: expected a path on the left-hand side of `+`, not `(dyn Auto)`
-  --> $DIR/trait-object-bad-parens.rs:13:16
+  --> $DIR/trait-object-bad-parens.rs:14:16
    |
 LL |     let _: Box<(dyn Auto) + Auto>;
    |                ^^^^^^^^^^^^^^^^^ expected a path

src/test/ui/privacy/privacy-sanity.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 pub trait Tr {
     fn f();

src/test/ui/privacy/private-in-public-non-principal-2.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 #[allow(private_in_public)]
 mod m {

src/test/ui/privacy/private-in-public-non-principal-2.stderr

@@ -1,5 +1,5 @@
 error: trait `m::PrivNonPrincipal` is private
-  --> $DIR/private-in-public-non-principal-2.rs:11:5
+  --> $DIR/private-in-public-non-principal-2.rs:12:5
    |
 LL |     m::leak_dyn_nonprincipal();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ private trait

src/test/ui/privacy/private-in-public-non-principal.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 pub trait PubPrincipal {}
 auto trait PrivNonPrincipal {}

src/test/ui/privacy/private-in-public-non-principal.stderr

@@ -1,5 +1,5 @@
 warning: private trait `PrivNonPrincipal` in public interface (error E0445)
-  --> $DIR/private-in-public-non-principal.rs:6:1
+  --> $DIR/private-in-public-non-principal.rs:7:1
    |
 LL | pub fn leak_dyn_nonprincipal() -> Box<dyn PubPrincipal + PrivNonPrincipal> { loop {} }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -15,7 +15,7 @@ LL |         pub fn check_doc_lint() {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/private-in-public-non-principal.rs:10:8
+  --> $DIR/private-in-public-non-principal.rs:11:8
    |
 LL | #[deny(missing_docs)]
    |        ^^^^^^^^^^^^

src/test/ui/specialization/defaultimpl/validation.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(specialization)]
 
 struct S;

src/test/ui/specialization/specialization-overlap-negative.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(specialization)]
 
 trait MyTrait {}

src/test/ui/specialization/specialization-polarity.rs

@@ -1,6 +1,7 @@
 // Make sure specialization cannot change impl polarity
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(specialization)]
 
 auto trait Foo {}

src/test/ui/specialization/specialization-polarity.stderr

@@ -1,5 +1,5 @@
 error[E0748]: found both positive and negative implementation of trait `Foo` for type `u8`:
-  --> $DIR/specialization-polarity.rs:9:1
+  --> $DIR/specialization-polarity.rs:10:1
    |
 LL | impl<T> Foo for T {}
    | ----------------- positive implementation here
@@ -7,7 +7,7 @@ LL | impl !Foo for u8 {}
    | ^^^^^^^^^^^^^^^^ negative implementation here
 
 error[E0748]: found both positive and negative implementation of trait `Bar` for type `u8`:
-  --> $DIR/specialization-polarity.rs:14:1
+  --> $DIR/specialization-polarity.rs:15:1
    |
 LL | impl<T> !Bar for T {}
    | ------------------ negative implementation here

src/test/ui/syntax-trait-polarity-feature-gate.stderr

@@ -5,7 +5,7 @@ LL | impl !Send for TestType {}
    |      ^^^^^
    |
    = note: see issue #13231 <https://github.com/rust-lang/rust/issues/13231> for more information
-   = help: add `#![feature(optin_builtin_traits)]` to the crate attributes to enable
+   = help: add `#![feature(negative_impls)]` to the crate attributes to enable
 
 error: aborting due to previous error
 

src/test/ui/syntax-trait-polarity.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/traits/auto-traits.rs

@@ -1,6 +1,7 @@
 // run-pass
 #![allow(unused_doc_comments)]
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Auto {}
 unsafe auto trait AutoUnsafe {}

src/test/ui/traits/negative-impls/auxiliary/foreign_trait.rs

@@ -1,6 +1,6 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
-pub trait ForeignTrait { }
+pub trait ForeignTrait {}
 
-impl ForeignTrait for u32 { }
+impl ForeignTrait for u32 {}
 impl !ForeignTrait for String {}

src/test/ui/traits/negative-impls/negated-auto-traits-error.rs

@@ -3,7 +3,7 @@
 // errors are not reported. This way, we make sure that, for each function, different
 // typeck phases are involved and all errors are reported.
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/traits/negative-impls/negated-auto-traits-rpass.rs

@@ -1,6 +1,6 @@
 // run-pass
 #![allow(unused_variables)]
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::marker::Send;
 

src/test/ui/traits/negative-impls/negative-default-impls.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![feature(specialization)]
 
 trait MyTrait {

src/test/ui/traits/negative-impls/negative-specializes-positive-item.rs

@@ -1,5 +1,5 @@
 #![feature(specialization)]
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // Negative impl for u32 cannot "specialize" the base impl.
 trait MyTrait {

src/test/ui/traits/negative-impls/negative-specializes-positive.rs

@@ -1,5 +1,5 @@
 #![feature(specialization)]
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // Negative impl for u32 cannot "specialize" the base impl.
 trait MyTrait {}

src/test/ui/traits/negative-impls/no-items.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 trait MyTrait {
     type Foo;

src/test/ui/traits/negative-impls/positive-specializes-negative.rs

@@ -1,5 +1,5 @@
 #![feature(specialization)]
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 trait MyTrait {}
 

src/test/ui/traits/negative-impls/rely-on-negative-impl-in-coherence.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // aux-build: foreign_trait.rs
 

src/test/ui/traits/negative-impls/typeck-negative-impls-builtin.rs

@@ -1,6 +1,6 @@
 // run-pass
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 #![allow(dead_code)]
 
 struct TestType;

src/test/ui/traits/overlap-not-permitted-for-builtin-trait.rs

@@ -1,5 +1,5 @@
 #![allow(dead_code)]
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 // Overlapping negative impls for `MyStruct` are not permitted:
 struct MyStruct;
@@ -7,5 +7,4 @@ impl !Send for MyStruct {}
 impl !Send for MyStruct {}
 //~^ ERROR conflicting implementations of trait
 
-fn main() {
-}
+fn main() {}

src/test/ui/traits/overlap-permitted-for-marker-traits.rs

@@ -0,0 +1,28 @@
+// run-pass
+// Tests for RFC 1268: we allow overlapping impls of marker traits,
+// that is, traits without items. In this case, a type `T` is
+// `MyMarker` if it is either `Debug` or `Display`.
+
+#![feature(marker_trait_attr)]
+#![feature(negative_impls)]
+
+use std::fmt::{Debug, Display};
+
+#[marker]
+trait MyMarker {}
+
+impl<T: Debug> MyMarker for T {}
+impl<T: Display> MyMarker for T {}
+
+fn foo<T: MyMarker>(t: T) -> T {
+    t
+}
+
+fn main() {
+    // Debug && Display:
+    assert_eq!(1, foo(1));
+    assert_eq!(2.0, foo(2.0));
+
+    // Debug && !Display:
+    assert_eq!(vec![1], foo(vec![1]));
+}

src/test/ui/traits/syntax-trait-polarity.rs

@@ -2,7 +2,7 @@
 #![allow(dead_code)]
 // pretty-expanded FIXME #23616
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 struct TestType;
 

src/test/ui/traits/traits-inductive-overflow-supertrait-oibit.rs

@@ -3,6 +3,7 @@
 // to be synthesized.
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Magic: Copy {} //~ ERROR E0568
 

src/test/ui/traits/traits-inductive-overflow-supertrait-oibit.stderr

@@ -1,5 +1,5 @@
 error[E0568]: auto traits cannot have super traits
-  --> $DIR/traits-inductive-overflow-supertrait-oibit.rs:7:19
+  --> $DIR/traits-inductive-overflow-supertrait-oibit.rs:8:19
    |
 LL | auto trait Magic: Copy {}
    |            -----  ^^^^ help: remove the super traits
@@ -7,7 +7,7 @@ LL | auto trait Magic: Copy {}
    |            auto trait cannot have super traits
 
 error[E0277]: the trait bound `NoClone: std::marker::Copy` is not satisfied
-  --> $DIR/traits-inductive-overflow-supertrait-oibit.rs:15:23
+  --> $DIR/traits-inductive-overflow-supertrait-oibit.rs:16:23
    |
 LL | fn copy<T: Magic>(x: T) -> (T, T) { (x, x) }
    |    ----    ----- required by this bound in `copy`

src/test/ui/typeck/typeck-auto-trait-no-supertraits-2.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Magic : Sized where Option<Self> : Magic {} //~ ERROR E0568
 impl<T:Magic> Magic for T {}

src/test/ui/typeck/typeck-auto-trait-no-supertraits-2.stderr

@@ -1,5 +1,5 @@
 error[E0568]: auto traits cannot have super traits
-  --> $DIR/typeck-auto-trait-no-supertraits-2.rs:3:20
+  --> $DIR/typeck-auto-trait-no-supertraits-2.rs:4:20
    |
 LL | auto trait Magic : Sized where Option<Self> : Magic {}
    |            -----   ^^^^^ help: remove the super traits

src/test/ui/typeck/typeck-auto-trait-no-supertraits.rs

@@ -23,6 +23,7 @@
 // }
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Magic: Copy {} //~ ERROR E0568
 impl<T:Magic> Magic for T {}

src/test/ui/typeck/typeck-auto-trait-no-supertraits.stderr

@@ -1,5 +1,5 @@
 error[E0568]: auto traits cannot have super traits
-  --> $DIR/typeck-auto-trait-no-supertraits.rs:27:19
+  --> $DIR/typeck-auto-trait-no-supertraits.rs:28:19
    |
 LL | auto trait Magic: Copy {}
    |            -----  ^^^^ help: remove the super traits

src/test/ui/typeck/typeck-default-trait-impl-constituent-types-2.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait MyTrait {}
 

src/test/ui/typeck/typeck-default-trait-impl-constituent-types-2.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `MyS2: MyTrait` is not satisfied in `(MyS2, MyS)`
-  --> $DIR/typeck-default-trait-impl-constituent-types-2.rs:16:5
+  --> $DIR/typeck-default-trait-impl-constituent-types-2.rs:17:5
    |
 LL | fn is_mytrait<T: MyTrait>() {}
    |    ----------    ------- required by this bound in `is_mytrait`

src/test/ui/typeck/typeck-default-trait-impl-constituent-types.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait MyTrait {}
 

src/test/ui/typeck/typeck-default-trait-impl-constituent-types.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `MyS2: MyTrait` is not satisfied
-  --> $DIR/typeck-default-trait-impl-constituent-types.rs:20:18
+  --> $DIR/typeck-default-trait-impl-constituent-types.rs:21:18
    |
 LL | fn is_mytrait<T: MyTrait>() {}
    |    ----------    ------- required by this bound in `is_mytrait`

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

@@ -3,7 +3,7 @@
 // Test that we do not consider associated types to be sendable without
 // some applicable trait bound (and we don't ICE).
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 extern crate tdticc_coherence_lib as lib;
 

src/test/ui/typeck/typeck-default-trait-impl-negation-send.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 struct MySendable {
    t: *mut u8

src/test/ui/typeck/typeck-default-trait-impl-negation-sync.rs

@@ -1,4 +1,4 @@
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 struct Managed;
 impl !Send for Managed {}

src/test/ui/typeck/typeck-default-trait-impl-negation.rs

@@ -1,4 +1,5 @@
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait MyTrait {}
 

src/test/ui/typeck/typeck-default-trait-impl-negation.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `ThisImplsUnsafeTrait: MyTrait` is not satisfied
-  --> $DIR/typeck-default-trait-impl-negation.rs:21:19
+  --> $DIR/typeck-default-trait-impl-negation.rs:22:19
    |
 LL | fn is_my_trait<T: MyTrait>() {}
    |    -----------    ------- required by this bound in `is_my_trait`
@@ -11,7 +11,7 @@ LL |     is_my_trait::<ThisImplsUnsafeTrait>();
              <ThisImplsUnsafeTrait as MyTrait>
 
 error[E0277]: the trait bound `ThisImplsTrait: MyUnsafeTrait` is not satisfied
-  --> $DIR/typeck-default-trait-impl-negation.rs:24:26
+  --> $DIR/typeck-default-trait-impl-negation.rs:25:26
    |
 LL | fn is_my_unsafe_trait<T: MyUnsafeTrait>() {}
    |    ------------------    ------------- required by this bound in `is_my_unsafe_trait`

src/test/ui/typeck/typeck-default-trait-impl-precedence.rs

@@ -4,6 +4,7 @@
 // impls whose types unify.
 
 #![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 auto trait Defaulted { }
 impl<'a,T:Signed> Defaulted for &'a T { }

src/test/ui/typeck/typeck-default-trait-impl-precedence.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `u32: Signed` is not satisfied
-  --> $DIR/typeck-default-trait-impl-precedence.rs:18:5
+  --> $DIR/typeck-default-trait-impl-precedence.rs:19:5
    |
 LL | fn is_defaulted<T:Defaulted>() { }
    |    ------------   --------- required by this bound in `is_defaulted`

src/test/ui/typeck/typeck-unsafe-always-share.rs

@@ -1,6 +1,6 @@
 // Verify that UnsafeCell is *always* !Sync regardless if `T` is sync.
 
-#![feature(optin_builtin_traits)]
+#![feature(negative_impls)]
 
 use std::cell::UnsafeCell;
 use std::marker::Sync;