Auto merge of #89550 - lcnr:coherence-specialization, r=nikomatsakis

do not emit overlap errors for impls failing the orphan check

this should finally allow us to merge #86986, see https://github.com/rust-lang/rust/pull/86986#discussion_r716059345 for more details.

r? `@nikomatsakis` cc `@eddyb`

24 files changed, 237 insertions, 263 deletions

diff --git a/src/test/ui/coherence/coherence-cross-crate-conflict.rs b/src/test/ui/coherence/coherence-cross-crate-conflict.rs
index 648e290a4b8..588630957c9 100644
--- a/src/test/ui/coherence/coherence-cross-crate-conflict.rs
+++ b/src/test/ui/coherence/coherence-cross-crate-conflict.rs
@@ -6,9 +6,7 @@
 extern crate trait_impl_conflict;
 use trait_impl_conflict::Foo;
 
-impl<A> Foo for A {
-    //~^ ERROR E0119
-    //~| ERROR E0210
+impl<A> Foo for A { //~ ERROR E0210
 }
 
 fn main() {
diff --git a/src/test/ui/coherence/coherence-cross-crate-conflict.stderr b/src/test/ui/coherence/coherence-cross-crate-conflict.stderr
index d0d86c72ffc..3d253d56a45 100644
--- a/src/test/ui/coherence/coherence-cross-crate-conflict.stderr
+++ b/src/test/ui/coherence/coherence-cross-crate-conflict.stderr
@@ -1,12 +1,3 @@
-error[E0119]: conflicting implementations of trait `trait_impl_conflict::Foo` for type `isize`
-  --> $DIR/coherence-cross-crate-conflict.rs:9:1
-   |
-LL | impl<A> Foo for A {
-   | ^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `trait_impl_conflict`:
-           - impl Foo for isize;
-
 error[E0210]: type parameter `A` must be used as the type parameter for some local type (e.g., `MyStruct<A>`)
   --> $DIR/coherence-cross-crate-conflict.rs:9:6
    |
@@ -16,7 +7,6 @@ LL | impl<A> Foo for A {
    = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
    = note: only traits defined in the current crate can be implemented for a type parameter
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0119, E0210.
-For more information about an error, try `rustc --explain E0119`.
+For more information about this error, try `rustc --explain E0210`.
diff --git a/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr b/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr
index c364c707ff9..91289148079 100644
--- a/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr
+++ b/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-negative.stderr
@@ -1,15 +1,3 @@
-error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
-  --> $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: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:23:1
    |
@@ -33,6 +21,18 @@ error[E0321]: cross-crate traits with a default impl, like `Send`, can only be i
 LL | impl !Send for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
+  --> $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:17:1
+   |
+LL | impl !Marker2 for dyn Object + Marker2 { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
+
 error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0117, E0321, E0371.
diff --git a/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr b/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr
index b80429794f9..056198374a4 100644
--- a/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr
+++ b/src/test/ui/coherence/coherence-impl-trait-for-marker-trait-positive.stderr
@@ -1,15 +1,3 @@
-error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
-  --> $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: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:23:1
    |
@@ -33,6 +21,18 @@ error[E0321]: cross-crate traits with a default impl, like `Send`, can only be i
 LL | unsafe impl Send for dyn Object + Marker2 {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't implement cross-crate trait with a default impl for non-struct/enum type
 
+error[E0371]: the object type `(dyn Object + Marker2 + 'static)` automatically implements the trait `Marker1`
+  --> $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:17:1
+   |
+LL | impl Marker2 for dyn Object + Marker2 { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `(dyn Object + Marker2 + 'static)` automatically implements trait `Marker2`
+
 error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0117, E0321, E0371.
diff --git a/src/test/ui/coherence/coherence-impls-copy.rs b/src/test/ui/coherence/coherence-impls-copy.rs
index a86ca0e5eac..4204fecc37e 100644
--- a/src/test/ui/coherence/coherence-impls-copy.rs
+++ b/src/test/ui/coherence/coherence-impls-copy.rs
@@ -3,8 +3,7 @@
 use std::marker::Copy;
 
 impl Copy for i32 {}
-//~^ ERROR E0119
-//~| ERROR E0117
+//~^ ERROR E0117
 enum TestE {
   A
 }
@@ -32,7 +31,6 @@ impl Copy for [MyType] {}
 //~^ ERROR E0206
 //~| ERROR E0117
 impl Copy for &'static [NotSync] {}
-//~^ ERROR E0119
-//~| ERROR E0117
+//~^ ERROR E0117
 fn main() {
 }
diff --git a/src/test/ui/coherence/coherence-impls-copy.stderr b/src/test/ui/coherence/coherence-impls-copy.stderr
index 2ac0706d72e..a7d6968a296 100644
--- a/src/test/ui/coherence/coherence-impls-copy.stderr
+++ b/src/test/ui/coherence/coherence-impls-copy.stderr
@@ -1,50 +1,3 @@
-error[E0119]: conflicting implementations of trait `std::marker::Copy` for type `i32`
-  --> $DIR/coherence-impls-copy.rs:5:1
-   |
-LL | impl Copy for i32 {}
-   | ^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl Copy for i32;
-
-error[E0119]: conflicting implementations of trait `std::marker::Copy` for type `&NotSync`
-  --> $DIR/coherence-impls-copy.rs:29:1
-   |
-LL | impl Copy for &'static NotSync {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl<T> Copy for &T
-             where T: ?Sized;
-
-error[E0119]: conflicting implementations of trait `std::marker::Copy` for type `&[NotSync]`
-  --> $DIR/coherence-impls-copy.rs:34:1
-   |
-LL | impl Copy for &'static [NotSync] {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl<T> Copy for &T
-             where T: ?Sized;
-
-error[E0206]: the trait `Copy` may not be implemented for this type
-  --> $DIR/coherence-impls-copy.rs:22:15
-   |
-LL | impl Copy for &'static mut MyType {}
-   |               ^^^^^^^^^^^^^^^^^^^ type is not a structure or enumeration
-
-error[E0206]: the trait `Copy` may not be implemented for this type
-  --> $DIR/coherence-impls-copy.rs:26:15
-   |
-LL | impl Copy for (MyType, MyType) {}
-   |               ^^^^^^^^^^^^^^^^ type is not a structure or enumeration
-
-error[E0206]: the trait `Copy` may not be implemented for this type
-  --> $DIR/coherence-impls-copy.rs:31:15
-   |
-LL | impl Copy for [MyType] {}
-   |               ^^^^^^^^ type is not a structure or enumeration
-
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/coherence-impls-copy.rs:5:1
    |
@@ -57,7 +10,7 @@ LL | impl Copy for i32 {}
    = 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/coherence-impls-copy.rs:26:1
+  --> $DIR/coherence-impls-copy.rs:25:1
    |
 LL | impl Copy for (MyType, MyType) {}
    | ^^^^^^^^^^^^^^----------------
@@ -68,7 +21,7 @@ LL | impl Copy for (MyType, MyType) {}
    = 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/coherence-impls-copy.rs:31:1
+  --> $DIR/coherence-impls-copy.rs:30:1
    |
 LL | impl Copy for [MyType] {}
    | ^^^^^^^^^^^^^^--------
@@ -79,7 +32,7 @@ LL | impl Copy for [MyType] {}
    = 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/coherence-impls-copy.rs:34:1
+  --> $DIR/coherence-impls-copy.rs:33:1
    |
 LL | impl Copy for &'static [NotSync] {}
    | ^^^^^^^^^^^^^^------------------
@@ -89,7 +42,35 @@ LL | impl Copy for &'static [NotSync] {}
    |
    = note: define and implement a trait or new type instead
 
-error: aborting due to 10 previous errors
+error[E0119]: conflicting implementations of trait `std::marker::Copy` for type `&NotSync`
+  --> $DIR/coherence-impls-copy.rs:28:1
+   |
+LL | impl Copy for &'static NotSync {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: conflicting implementation in crate `core`:
+           - impl<T> Copy for &T
+             where T: ?Sized;
+
+error[E0206]: the trait `Copy` may not be implemented for this type
+  --> $DIR/coherence-impls-copy.rs:21:15
+   |
+LL | impl Copy for &'static mut MyType {}
+   |               ^^^^^^^^^^^^^^^^^^^ type is not a structure or enumeration
+
+error[E0206]: the trait `Copy` may not be implemented for this type
+  --> $DIR/coherence-impls-copy.rs:25:15
+   |
+LL | impl Copy for (MyType, MyType) {}
+   |               ^^^^^^^^^^^^^^^^ type is not a structure or enumeration
+
+error[E0206]: the trait `Copy` may not be implemented for this type
+  --> $DIR/coherence-impls-copy.rs:30:15
+   |
+LL | impl Copy for [MyType] {}
+   |               ^^^^^^^^ type is not a structure or enumeration
+
+error: aborting due to 8 previous errors
 
 Some errors have detailed explanations: E0117, E0119, E0206.
 For more information about an error, try `rustc --explain E0117`.
diff --git a/src/test/ui/coherence/coherence-impls-send.rs b/src/test/ui/coherence/coherence-impls-send.rs
index e00cb9a7c5b..b7b57c602b8 100644
--- a/src/test/ui/coherence/coherence-impls-send.rs
+++ b/src/test/ui/coherence/coherence-impls-send.rs
@@ -23,7 +23,6 @@ unsafe impl Send for [MyType] {}
 //~^ ERROR E0117
 
 unsafe impl Send for &'static [NotSync] {}
-//~^ ERROR conflicting implementations of trait
-//~| ERROR only traits defined in the current crate
+//~^ ERROR only traits defined in the current crate
 
 fn main() {}
diff --git a/src/test/ui/coherence/coherence-impls-send.stderr b/src/test/ui/coherence/coherence-impls-send.stderr
index 46e9e7e986c..dd1fd1b0dce 100644
--- a/src/test/ui/coherence/coherence-impls-send.stderr
+++ b/src/test/ui/coherence/coherence-impls-send.stderr
@@ -1,14 +1,3 @@
-error[E0119]: conflicting implementations of trait `std::marker::Send` for type `&[NotSync]`
-  --> $DIR/coherence-impls-send.rs:25:1
-   |
-LL | unsafe impl Send for &'static [NotSync] {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl<T> Send for &T
-             where T: Sync, T: ?Sized;
-   = note: upstream crates may add a new impl of trait `std::marker::Sync` for type `[NotSync]` in future versions
-
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/coherence-impls-send.rs:16:1
    |
@@ -48,7 +37,7 @@ LL | unsafe impl Send for &'static [NotSync] {}
    |
    = note: define and implement a trait or new type instead
 
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0117, E0119, E0321.
+Some errors have detailed explanations: E0117, E0321.
 For more information about an error, try `rustc --explain E0117`.
diff --git a/src/test/ui/coherence/coherence-impls-sized.stderr b/src/test/ui/coherence/coherence-impls-sized.stderr
index 3b0a9fc60a2..9cf5ed38c9c 100644
--- a/src/test/ui/coherence/coherence-impls-sized.stderr
+++ b/src/test/ui/coherence/coherence-impls-sized.stderr
@@ -1,3 +1,36 @@
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+  --> $DIR/coherence-impls-sized.rs:20:1
+   |
+LL | impl Sized for (MyType, MyType) {}
+   | ^^^^^^^^^^^^^^^----------------
+   | |              |
+   | |              this is not defined in the current crate because tuples are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = 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/coherence-impls-sized.rs:27:1
+   |
+LL | impl Sized for [MyType] {}
+   | ^^^^^^^^^^^^^^^--------
+   | |              |
+   | |              this is not defined in the current crate because slices are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = 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/coherence-impls-sized.rs:31:1
+   |
+LL | impl Sized for &'static [NotSync] {}
+   | ^^^^^^^^^^^^^^^------------------
+   | |              |
+   | |              this is not defined in the current crate because slices are always foreign
+   | impl doesn't use only types from inside the current crate
+   |
+   = note: define and implement a trait or new type instead
+
 error[E0322]: explicit impls for the `Sized` trait are not permitted
   --> $DIR/coherence-impls-sized.rs:14:1
    |
@@ -34,39 +67,6 @@ error[E0322]: explicit impls for the `Sized` trait are not permitted
 LL | impl Sized for &'static [NotSync] {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl of 'Sized' not allowed
 
-error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/coherence-impls-sized.rs:20:1
-   |
-LL | impl Sized for (MyType, MyType) {}
-   | ^^^^^^^^^^^^^^^----------------
-   | |              |
-   | |              this is not defined in the current crate because tuples are always foreign
-   | impl doesn't use only types from inside the current crate
-   |
-   = 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/coherence-impls-sized.rs:27:1
-   |
-LL | impl Sized for [MyType] {}
-   | ^^^^^^^^^^^^^^^--------
-   | |              |
-   | |              this is not defined in the current crate because slices are always foreign
-   | impl doesn't use only types from inside the current crate
-   |
-   = 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/coherence-impls-sized.rs:31:1
-   |
-LL | impl Sized for &'static [NotSync] {}
-   | ^^^^^^^^^^^^^^^------------------
-   | |              |
-   | |              this is not defined in the current crate because slices are always foreign
-   | impl doesn't use only types from inside the current crate
-   |
-   = note: define and implement a trait or new type instead
-
 error: aborting due to 9 previous errors
 
 Some errors have detailed explanations: E0117, E0322.
diff --git a/src/test/ui/coherence/coherence-orphan.stderr b/src/test/ui/coherence/coherence-orphan.stderr
index 52d2cc88cbe..051a519ee14 100644
--- a/src/test/ui/coherence/coherence-orphan.stderr
+++ b/src/test/ui/coherence/coherence-orphan.stderr
@@ -1,22 +1,22 @@
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
-  --> $DIR/coherence-orphan.rs:10:1
+  --> $DIR/coherence-orphan.rs:17:1
    |
-LL | impl TheTrait<usize> for isize { }
-   | ^^^^^---------------^^^^^-----
-   | |    |                   |
-   | |    |                   `isize` is not defined in the current crate
-   | |    `usize` is not defined in the current crate
+LL | impl !Send for Vec<isize> { }
+   | ^^^^^^^^^^^^^^^----------
+   | |              |
+   | |              `Vec` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = 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/coherence-orphan.rs:17:1
+  --> $DIR/coherence-orphan.rs:10:1
    |
-LL | impl !Send for Vec<isize> { }
-   | ^^^^^^^^^^^^^^^----------
-   | |              |
-   | |              `Vec` is not defined in the current crate
+LL | impl TheTrait<usize> for isize { }
+   | ^^^^^---------------^^^^^-----
+   | |    |                   |
+   | |    |                   `isize` is not defined in the current crate
+   | |    `usize` is not defined in the current crate
    | impl doesn't use only types from inside the current crate
    |
    = note: define and implement a trait or new type instead
diff --git a/src/test/ui/dropck/drop-on-non-struct.stderr b/src/test/ui/dropck/drop-on-non-struct.stderr
index 3991c44f2ed..e52728f3781 100644
--- a/src/test/ui/dropck/drop-on-non-struct.stderr
+++ b/src/test/ui/dropck/drop-on-non-struct.stderr
@@ -4,12 +4,6 @@ error[E0412]: cannot find type `Nonexistent` in this scope
 LL | impl Drop for Nonexistent {
    |               ^^^^^^^^^^^ not found in this scope
 
-error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
-  --> $DIR/drop-on-non-struct.rs:1:19
-   |
-LL | impl<'a> Drop for &'a mut isize {
-   |                   ^^^^^^^^^^^^^ must be a struct, enum, or union
-
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/drop-on-non-struct.rs:1:1
    |
@@ -21,6 +15,12 @@ LL | impl<'a> Drop for &'a mut isize {
    |
    = note: define and implement a trait or new type instead
 
+error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
+  --> $DIR/drop-on-non-struct.rs:1:19
+   |
+LL | impl<'a> Drop for &'a mut isize {
+   |                   ^^^^^^^^^^^^^ must be a struct, enum, or union
+
 error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0117, E0120, E0412.
diff --git a/src/test/ui/error-codes/E0117.stderr b/src/test/ui/error-codes/E0117.stderr
index b48a1d8e50d..cdbafff2a20 100644
--- a/src/test/ui/error-codes/E0117.stderr
+++ b/src/test/ui/error-codes/E0117.stderr
@@ -1,9 +1,3 @@
-error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
-  --> $DIR/E0117.rs:1:15
-   |
-LL | impl Drop for u32 {}
-   |               ^^^ must be a struct, enum, or union
-
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/E0117.rs:1:1
    |
@@ -15,6 +9,12 @@ LL | impl Drop for u32 {}
    |
    = note: define and implement a trait or new type instead
 
+error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
+  --> $DIR/E0117.rs:1:15
+   |
+LL | impl Drop for u32 {}
+   |               ^^^ must be a struct, enum, or union
+
 error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0117, E0120.
diff --git a/src/test/ui/error-codes/e0119/complex-impl.rs b/src/test/ui/error-codes/e0119/complex-impl.rs
index 7dbf93ada5e..9149e4ce58e 100644
--- a/src/test/ui/error-codes/e0119/complex-impl.rs
+++ b/src/test/ui/error-codes/e0119/complex-impl.rs
@@ -7,6 +7,5 @@ use complex_impl_support::{External, M};
 struct Q;
 
 impl<R> External for (Q, R) {} //~ ERROR only traits defined
-//~^ ERROR conflicting implementations of trait
 
 fn main() {}
diff --git a/src/test/ui/error-codes/e0119/complex-impl.stderr b/src/test/ui/error-codes/e0119/complex-impl.stderr
index 6a1a502749a..654073eec26 100644
--- a/src/test/ui/error-codes/e0119/complex-impl.stderr
+++ b/src/test/ui/error-codes/e0119/complex-impl.stderr
@@ -1,13 +1,3 @@
-error[E0119]: conflicting implementations of trait `complex_impl_support::External` for type `(Q, complex_impl_support::M<'_, '_, '_, std::boxed::Box<_>, _, _>)`
-  --> $DIR/complex-impl.rs:9:1
-   |
-LL | impl<R> External for (Q, R) {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `complex_impl_support`:
-           - impl<'a, 'b, 'c, T, U, V, W> External for (T, M<'a, 'b, 'c, Box<U>, V, W>)
-             where <U as FnOnce<(T,)>>::Output == V, <V as Iterator>::Item == T, 'b: 'a, T: 'a, U: 'static, U: FnOnce<(T,)>, V: Iterator, V: Clone, W: Add, <W as Add>::Output: Copy;
-
 error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/complex-impl.rs:9:1
    |
@@ -19,7 +9,6 @@ LL | impl<R> External for (Q, R) {}
    |
    = note: define and implement a trait or new type instead
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0117, E0119.
-For more information about an error, try `rustc --explain E0117`.
+For more information about this error, try `rustc --explain E0117`.
diff --git a/src/test/ui/error-codes/e0119/issue-28981.rs b/src/test/ui/error-codes/e0119/issue-28981.rs
index c31b212b25a..5fb7e9a9913 100644
--- a/src/test/ui/error-codes/e0119/issue-28981.rs
+++ b/src/test/ui/error-codes/e0119/issue-28981.rs
@@ -3,6 +3,5 @@ use std::ops::Deref;
 struct Foo;
 
 impl<Foo> Deref for Foo { } //~ ERROR must be used
-//~^ ERROR conflicting implementations
 
 fn main() {}
diff --git a/src/test/ui/error-codes/e0119/issue-28981.stderr b/src/test/ui/error-codes/e0119/issue-28981.stderr
index 56e8e1eb540..97b570bc7ac 100644
--- a/src/test/ui/error-codes/e0119/issue-28981.stderr
+++ b/src/test/ui/error-codes/e0119/issue-28981.stderr
@@ -1,13 +1,3 @@
-error[E0119]: conflicting implementations of trait `std::ops::Deref` for type `&_`
-  --> $DIR/issue-28981.rs:5:1
-   |
-LL | impl<Foo> Deref for Foo { }
-   | ^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl<T> Deref for &T
-             where T: ?Sized;
-
 error[E0210]: type parameter `Foo` must be used as the type parameter for some local type (e.g., `MyStruct<Foo>`)
   --> $DIR/issue-28981.rs:5:6
    |
@@ -17,7 +7,6 @@ LL | impl<Foo> Deref for Foo { }
    = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
    = note: only traits defined in the current crate can be implemented for a type parameter
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0119, E0210.
-For more information about an error, try `rustc --explain E0119`.
+For more information about this error, try `rustc --explain E0210`.
diff --git a/src/test/ui/issues/issue-41974.rs b/src/test/ui/issues/issue-41974.rs
index 7875b432d7b..10c363479a3 100644
--- a/src/test/ui/issues/issue-41974.rs
+++ b/src/test/ui/issues/issue-41974.rs
@@ -4,9 +4,9 @@ struct Flags;
 trait A {
 }
 
-impl<T> Drop for T where T: A { //~ ERROR E0119
-                                //~^ ERROR E0120
-                                //~| ERROR E0210
+impl<T> Drop for T where T: A {
+    //~^ ERROR E0120
+    //~| ERROR E0210
     fn drop(&mut self) {
     }
 }
diff --git a/src/test/ui/issues/issue-41974.stderr b/src/test/ui/issues/issue-41974.stderr
index 11d77857d60..fcbb4014025 100644
--- a/src/test/ui/issues/issue-41974.stderr
+++ b/src/test/ui/issues/issue-41974.stderr
@@ -1,13 +1,11 @@
-error[E0119]: conflicting implementations of trait `std::ops::Drop` for type `std::boxed::Box<_, _>`
-  --> $DIR/issue-41974.rs:7:1
+error[E0210]: type parameter `T` must be used as the type parameter for some local type (e.g., `MyStruct<T>`)
+  --> $DIR/issue-41974.rs:7:6
    |
 LL | impl<T> Drop for T where T: A {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |      ^ type parameter `T` must be used as the type parameter for some local type
    |
-   = note: conflicting implementation in crate `alloc`:
-           - impl<T, A> Drop for Box<T, A>
-             where A: Allocator, T: ?Sized;
-   = note: downstream crates may implement trait `A` for type `std::boxed::Box<_, _>`
+   = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
+   = note: only traits defined in the current crate can be implemented for a type parameter
 
 error[E0120]: the `Drop` trait may only be implemented for structs, enums, and unions
   --> $DIR/issue-41974.rs:7:18
@@ -15,16 +13,7 @@ error[E0120]: the `Drop` trait may only be implemented for structs, enums, and u
 LL | impl<T> Drop for T where T: A {
    |                  ^ must be a struct, enum, or union
 
-error[E0210]: type parameter `T` must be used as the type parameter for some local type (e.g., `MyStruct<T>`)
-  --> $DIR/issue-41974.rs:7:6
-   |
-LL | impl<T> Drop for T where T: A {
-   |      ^ type parameter `T` must be used as the type parameter for some local type
-   |
-   = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
-   = note: only traits defined in the current crate can be implemented for a type parameter
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0119, E0120, E0210.
-For more information about an error, try `rustc --explain E0119`.
+Some errors have detailed explanations: E0120, E0210.
+For more information about an error, try `rustc --explain E0120`.
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.rs b/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.rs
index 4b2f049b99d..961968186de 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.rs
@@ -2,9 +2,8 @@
 
 pub struct Int(i32);
 
-impl const std::ops::Add for i32 {
-    //~^ ERROR conflicting implementations of trait
-    //~| ERROR only traits defined in the current crate can be implemented for arbitrary types
+impl const std::ops::Add for i32 { //~ ERROR type annotations needed
+    //~^ ERROR only traits defined in the current crate can be implemented for arbitrary types
     type Output = Self;
 
     fn add(self, rhs: Self) -> Self {
@@ -12,7 +11,7 @@ impl const std::ops::Add for i32 {
     }
 }
 
-impl std::ops::Add for Int {
+impl std::ops::Add for Int { //~ ERROR type annotations needed
     type Output = Self;
 
     fn add(self, rhs: Self) -> Self {
@@ -20,7 +19,7 @@ impl std::ops::Add for Int {
     }
 }
 
-impl const std::ops::Add for Int {
+impl const std::ops::Add for Int { //~ ERROR type annotations needed
     //~^ ERROR conflicting implementations of trait
     type Output = Self;
 
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.stderr b/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.stderr
index a0960a21d46..785095c29ae 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.stderr
@@ -1,14 +1,17 @@
-error[E0119]: conflicting implementations of trait `std::ops::Add` for type `i32`
+error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
   --> $DIR/const-and-non-const-impl.rs:5:1
    |
 LL | impl const std::ops::Add for i32 {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^-------------^^^^^---
+   | |          |                 |
+   | |          |                 `i32` is not defined in the current crate
+   | |          `i32` is not defined in the current crate
+   | impl doesn't use only types from inside the current crate
    |
-   = note: conflicting implementation in crate `core`:
-           - impl Add for i32;
+   = note: define and implement a trait or new type instead
 
 error[E0119]: conflicting implementations of trait `std::ops::Add` for type `Int`
-  --> $DIR/const-and-non-const-impl.rs:23:1
+  --> $DIR/const-and-non-const-impl.rs:22:1
    |
 LL | impl std::ops::Add for Int {
    | -------------------------- first implementation here
@@ -16,19 +19,83 @@ LL | impl std::ops::Add for Int {
 LL | impl const std::ops::Add for Int {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `Int`
 
-error[E0117]: only traits defined in the current crate can be implemented for arbitrary types
+error[E0283]: type annotations needed
+  --> $DIR/const-and-non-const-impl.rs:5:12
+   |
+LL | impl const std::ops::Add for i32 {
+   |            ^^^^^^^^^^^^^ cannot infer type for type `i32`
+   |
+note: multiple `impl`s satisfying `i32: Add` found
   --> $DIR/const-and-non-const-impl.rs:5:1
    |
 LL | impl const std::ops::Add for i32 {
-   | ^^^^^^^^^^^-------------^^^^^---
-   | |          |                 |
-   | |          |                 `i32` is not defined in the current crate
-   | |          `i32` is not defined in the current crate
-   | impl doesn't use only types from inside the current crate
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: and another `impl` found in the `core` crate: `impl Add for i32;`
+note: required by a bound in `Add`
+  --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
    |
-   = note: define and implement a trait or new type instead
+LL | / pub trait Add<Rhs = Self> {
+LL | |     /// The resulting type after applying the `+` operator.
+LL | |     #[stable(feature = "rust1", since = "1.0.0")]
+LL | |     type Output;
+...  |
+LL | |     fn add(self, rhs: Rhs) -> Self::Output;
+LL | | }
+   | |_^ required by this bound in `Add`
+
+error[E0283]: type annotations needed
+  --> $DIR/const-and-non-const-impl.rs:14:6
+   |
+LL | impl std::ops::Add for Int {
+   |      ^^^^^^^^^^^^^ cannot infer type for struct `Int`
+   |
+note: multiple `impl`s satisfying `Int: Add` found
+  --> $DIR/const-and-non-const-impl.rs:14:1
+   |
+LL | impl std::ops::Add for Int {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | impl const std::ops::Add for Int {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: required by a bound in `Add`
+  --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
+   |
+LL | / pub trait Add<Rhs = Self> {
+LL | |     /// The resulting type after applying the `+` operator.
+LL | |     #[stable(feature = "rust1", since = "1.0.0")]
+LL | |     type Output;
+...  |
+LL | |     fn add(self, rhs: Rhs) -> Self::Output;
+LL | | }
+   | |_^ required by this bound in `Add`
+
+error[E0283]: type annotations needed
+  --> $DIR/const-and-non-const-impl.rs:22:12
+   |
+LL | impl const std::ops::Add for Int {
+   |            ^^^^^^^^^^^^^ cannot infer type for struct `Int`
+   |
+note: multiple `impl`s satisfying `Int: Add` found
+  --> $DIR/const-and-non-const-impl.rs:14:1
+   |
+LL | impl std::ops::Add for Int {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | impl const std::ops::Add for Int {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: required by a bound in `Add`
+  --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
+   |
+LL | / pub trait Add<Rhs = Self> {
+LL | |     /// The resulting type after applying the `+` operator.
+LL | |     #[stable(feature = "rust1", since = "1.0.0")]
+LL | |     type Output;
+...  |
+LL | |     fn add(self, rhs: Rhs) -> Self::Output;
+LL | | }
+   | |_^ required by this bound in `Add`
 
-error: aborting due to 3 previous errors
+error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0117, E0119.
+Some errors have detailed explanations: E0117, E0119, E0283.
 For more information about an error, try `rustc --explain E0117`.
diff --git a/src/test/ui/traits/alias/issue-83613.stderr b/src/test/ui/traits/alias/issue-83613.stderr
index 0ab39ae6672..6a3498a3893 100644
--- a/src/test/ui/traits/alias/issue-83613.stderr
+++ b/src/test/ui/traits/alias/issue-83613.stderr
@@ -1,11 +1,3 @@
-error[E0119]: conflicting implementations of trait `AnotherTrait` for type `impl OpaqueTrait`
-  --> $DIR/issue-83613.rs:10:1
-   |
-LL | impl<T: Send> AnotherTrait for T {}
-   | -------------------------------- first implementation here
-LL | impl AnotherTrait for OpaqueType {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `impl OpaqueTrait`
-
 error: cannot implement trait on type alias impl trait
   --> $DIR/issue-83613.rs:10:1
    |
@@ -18,6 +10,14 @@ note: type alias impl trait defined here
 LL | type OpaqueType = impl OpaqueTrait;
    |                   ^^^^^^^^^^^^^^^^
 
+error[E0119]: conflicting implementations of trait `AnotherTrait` for type `impl OpaqueTrait`
+  --> $DIR/issue-83613.rs:10:1
+   |
+LL | impl<T: Send> AnotherTrait for T {}
+   | -------------------------------- first implementation here
+LL | impl AnotherTrait for OpaqueType {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `impl OpaqueTrait`
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0119`.
diff --git a/src/test/ui/traits/issue-78372.stderr b/src/test/ui/traits/issue-78372.stderr
index 0150ff41303..49a9f479368 100644
--- a/src/test/ui/traits/issue-78372.stderr
+++ b/src/test/ui/traits/issue-78372.stderr
@@ -50,12 +50,6 @@ LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
    |
    = help: add `#![feature(dispatch_from_dyn)]` to the crate attributes to enable
 
-error[E0378]: the trait `DispatchFromDyn` may only be implemented for a coercion between structures
-  --> $DIR/issue-78372.rs:3:1
-   |
-LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error[E0210]: type parameter `T` must be covered by another type when it appears before the first local type (`Smaht<[type error], [type error]>`)
   --> $DIR/issue-78372.rs:3:6
    |
@@ -65,6 +59,12 @@ LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
    = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local, and no uncovered type parameters appear before that first local type
    = note: in this case, 'before' refers to the following order: `impl<..> ForeignTrait<T1, ..., Tn> for T0`, where `T0` is the first and `Tn` is the last
 
+error[E0378]: the trait `DispatchFromDyn` may only be implemented for a coercion between structures
+  --> $DIR/issue-78372.rs:3:1
+   |
+LL | impl<T> DispatchFromDyn<Smaht<U, MISC>> for T {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0210, E0378, E0412, E0658.
diff --git a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs
index c46c4715924..685d76ee36f 100644
--- a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs
+++ b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.rs
@@ -8,8 +8,7 @@ trait MyTrait {}
 impl MyTrait for () {}
 
 impl<F> FnOnce<()> for &F {
-    //~^ ERROR conflicting implementations
-    //~| ERROR type parameter `F` must be used
+    //~^ ERROR type parameter `F` must be used
     type Output = impl MyTrait;
     extern "rust-call" fn call_once(self, _: ()) -> Self::Output {}
 }
diff --git a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr
index e1e259187f5..b93ea955c89 100644
--- a/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr
+++ b/src/test/ui/type-alias-impl-trait/incoherent-assoc-imp-trait.stderr
@@ -1,13 +1,3 @@
-error[E0119]: conflicting implementations of trait `std::ops::FnOnce<()>` for type `&_`
-  --> $DIR/incoherent-assoc-imp-trait.rs:10:1
-   |
-LL | impl<F> FnOnce<()> for &F {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: conflicting implementation in crate `core`:
-           - impl<A, F> FnOnce<A> for &F
-             where F: Fn<A>, F: ?Sized;
-
 error[E0210]: type parameter `F` must be used as the type parameter for some local type (e.g., `MyStruct<F>`)
   --> $DIR/incoherent-assoc-imp-trait.rs:10:6
    |
@@ -17,7 +7,6 @@ LL | impl<F> FnOnce<()> for &F {
    = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local
    = note: only traits defined in the current crate can be implemented for a type parameter
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0119, E0210.
-For more information about an error, try `rustc --explain E0119`.
+For more information about this error, try `rustc --explain E0210`.