Also test under next solver

tests/ui/impl-trait/recursive-bound-eval.next.stderr

@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/recursive-bound-eval.rs:20:13
+   |
+LL |     move || recursive_fn().parse()
+   |             ^^^^^^^^^^^^^^ cannot infer type
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0282`.

tests/ui/impl-trait/recursive-bound-eval.rs

@@ -1,7 +1,10 @@
 //! Test that we can evaluate nested obligations when invoking methods on recursive calls on
 //! an RPIT.
 
-//@ check-pass
+//@revisions: next current
+//@[next] compile-flags: -Znext-solver
+
+//@[current] check-pass
 
 pub trait Parser<E> {
     fn parse(&self) -> E;
@@ -15,6 +18,7 @@ fn parse(&self) -> E {
 
 pub fn recursive_fn<E>() -> impl Parser<E> {
     move || recursive_fn().parse()
+    //[next]~^ ERROR: type annotations needed
 }
 
 fn main() {}

tests/ui/type-alias-impl-trait/issue-84660-unsoundness.current.stderr

@@ -1,5 +1,5 @@
 error[E0119]: conflicting implementations of trait `Trait<Bar, _>`
-  --> $DIR/issue-84660-unsoundness.rs:23:1
+  --> $DIR/issue-84660-unsoundness.rs:28:1
    |
 LL | impl<In, Out> Trait<Bar, In> for Out {
    | ------------------------------------ first implementation here

tests/ui/type-alias-impl-trait/issue-84660-unsoundness.next.stderr

@@ -0,0 +1,23 @@
+error[E0284]: type annotations needed: cannot satisfy `<Out as Trait<Bar, In>>::Out == ()`
+  --> $DIR/issue-84660-unsoundness.rs:22:37
+   |
+LL |       fn convert(_i: In) -> Self::Out {
+   |  _____________________________________^
+LL | |
+LL | |         unreachable!();
+LL | |     }
+   | |_____^ cannot satisfy `<Out as Trait<Bar, In>>::Out == ()`
+
+error[E0119]: conflicting implementations of trait `Trait<Bar, _>`
+  --> $DIR/issue-84660-unsoundness.rs:28:1
+   |
+LL | impl<In, Out> Trait<Bar, In> for Out {
+   | ------------------------------------ first implementation here
+...
+LL | impl<In, Out> Trait<(), In> for Out {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0119, E0284.
+For more information about an error, try `rustc --explain E0119`.

tests/ui/type-alias-impl-trait/issue-84660-unsoundness.rs

@@ -1,6 +1,10 @@
 // Another example from issue #84660, this time weaponized as a safe transmute: an opaque type in an
 // impl header being accepted was used to create unsoundness.
 
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 #![feature(type_alias_impl_trait)]
 
 trait Foo {}
@@ -16,11 +20,13 @@ trait Trait<T, In> {
 impl<In, Out> Trait<Bar, In> for Out {
     type Out = Out;
     fn convert(_i: In) -> Self::Out {
+        //[next]~^  ERROR: cannot satisfy `<Out as Trait<Bar, In>>::Out == ()`
         unreachable!();
     }
 }
 
-impl<In, Out> Trait<(), In> for Out { //~ ERROR conflicting implementations of trait `Trait<Bar, _>`
+impl<In, Out> Trait<(), In> for Out {
+    //~^ ERROR conflicting implementations of trait `Trait<Bar, _>`
     type Out = In;
     fn convert(i: In) -> Self::Out {
         i

tests/ui/type-alias-impl-trait/nested-tait-inference.current.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `(): Foo<FooX>` is not satisfied
-  --> $DIR/nested-tait-inference.rs:12:13
+  --> $DIR/nested-tait-inference.rs:17:13
    |
 LL | fn foo() -> impl Foo<FooX> {
    |             ^^^^^^^^^^^^^^ the trait `Foo<FooX>` is not implemented for `()`

tests/ui/type-alias-impl-trait/nested-tait-inference.rs

@@ -1,18 +1,23 @@
 #![feature(type_alias_impl_trait)]
 #![allow(dead_code)]
 
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@[next] check-pass
+
 use std::fmt::Debug;
 
 type FooX = impl Debug;
 
-trait Foo<A> { }
+trait Foo<A> {}
 
-impl Foo<()> for () { }
+impl Foo<()> for () {}
 
 fn foo() -> impl Foo<FooX> {
-    //~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
+    //[current]~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
     // FIXME(type-alias-impl-trait): We could probably make this work.
     ()
 }
 
-fn main() { }
+fn main() {}

tests/ui/type-alias-impl-trait/nested-tait-inference2.current.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the trait bound `(): Foo<FooX>` is not satisfied
-  --> $DIR/nested-tait-inference2.rs:13:13
+  --> $DIR/nested-tait-inference2.rs:17:13
    |
 LL | fn foo() -> impl Foo<FooX> {
    |             ^^^^^^^^^^^^^^ the trait `Foo<FooX>` is not implemented for `()`

tests/ui/type-alias-impl-trait/nested-tait-inference2.next.stderr

@@ -0,0 +1,9 @@
+error[E0284]: type annotations needed: cannot satisfy `impl Foo<FooX> == ()`
+  --> $DIR/nested-tait-inference2.rs:19:5
+   |
+LL |     ()
+   |     ^^ cannot satisfy `impl Foo<FooX> == ()`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0284`.

tests/ui/type-alias-impl-trait/nested-tait-inference2.rs

@@ -1,6 +1,10 @@
 #![feature(type_alias_impl_trait)]
 #![allow(dead_code)]
 
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 use std::fmt::Debug;
 
 type FooX = impl Debug;
@@ -11,8 +15,9 @@ impl Foo<()> for () {}
 impl Foo<u32> for () {}
 
 fn foo() -> impl Foo<FooX> {
-    //~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
+    //[current]~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
     ()
+    //[next]~^ ERROR: cannot satisfy `impl Foo<FooX> == ()`
 }
 
 fn main() {}