Rollup merge of #140306 - lcnr:specialization-new, r=compiler-errors

handle specialization in the new trait solver

fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/187
also fixes the regression in `plonky2_field` from https://github.com/rust-lang/trait-system-refactor-initiative/issues/188

cc https://github.com/rust-lang/rust/pull/111994

r? ```@compiler-errors```

13 files changed, 173 insertions, 37 deletions

diff --git a/tests/ui/specialization/prefer-specializing-impl-over-default.current.stderr b/tests/ui/specialization/prefer-specializing-impl-over-default.current.stderr
new file mode 100644
index 00000000000..7e3df0c83f9
--- /dev/null
+++ b/tests/ui/specialization/prefer-specializing-impl-over-default.current.stderr
@@ -0,0 +1,12 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/prefer-specializing-impl-over-default.rs:5:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/specialization/prefer-specializing-impl-over-default.next.stderr b/tests/ui/specialization/prefer-specializing-impl-over-default.next.stderr
new file mode 100644
index 00000000000..7e3df0c83f9
--- /dev/null
+++ b/tests/ui/specialization/prefer-specializing-impl-over-default.next.stderr
@@ -0,0 +1,12 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/prefer-specializing-impl-over-default.rs:5:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/specialization/prefer-specializing-impl-over-default.rs b/tests/ui/specialization/prefer-specializing-impl-over-default.rs
new file mode 100644
index 00000000000..af6837b30ca
--- /dev/null
+++ b/tests/ui/specialization/prefer-specializing-impl-over-default.rs
@@ -0,0 +1,29 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+//@ check-pass
+#![feature(specialization)]
+//~^ WARN the feature `specialization` is incomplete
+
+trait WithAssoc: 'static {
+    type Assoc;
+}
+impl<T: 'static> WithAssoc for (T,) {
+    type Assoc = ();
+}
+
+struct GenericArray<U: WithAssoc>(U::Assoc);
+
+trait AbiExample {
+    fn example();
+}
+impl<U: WithAssoc> AbiExample for GenericArray<U> {
+    fn example() {}
+}
+impl<T> AbiExample for T {
+    default fn example() {}
+}
+
+fn main() {
+    let _ = GenericArray::<((),)>::example();
+}
diff --git a/tests/ui/specialization/specialization-default-projection.stderr b/tests/ui/specialization/specialization-default-projection.current.stderr
index b8b81876d81..038c379c43e 100644
--- a/tests/ui/specialization/specialization-default-projection.stderr
+++ b/tests/ui/specialization/specialization-default-projection.current.stderr
@@ -1,5 +1,5 @@
 warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/specialization-default-projection.rs:1:12
+  --> $DIR/specialization-default-projection.rs:5:12
    |
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
@@ -9,7 +9,7 @@ LL | #![feature(specialization)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0308]: mismatched types
-  --> $DIR/specialization-default-projection.rs:21:5
+  --> $DIR/specialization-default-projection.rs:25:5
    |
 LL | fn generic<T>() -> <T as Foo>::Assoc {
    |                    ----------------- expected `<T as Foo>::Assoc` because of return type
@@ -23,7 +23,7 @@ LL |     ()
    = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
 
 error[E0308]: mismatched types
-  --> $DIR/specialization-default-projection.rs:28:5
+  --> $DIR/specialization-default-projection.rs:32:5
    |
 LL | fn monomorphic() -> () {
    |                     -- expected `()` because of return type
diff --git a/tests/ui/specialization/specialization-default-projection.next.stderr b/tests/ui/specialization/specialization-default-projection.next.stderr
new file mode 100644
index 00000000000..9111f173a9c
--- /dev/null
+++ b/tests/ui/specialization/specialization-default-projection.next.stderr
@@ -0,0 +1,43 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/specialization-default-projection.rs:5:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+  --> $DIR/specialization-default-projection.rs:25:5
+   |
+LL | fn generic<T>() -> <T as Foo>::Assoc {
+   |                    ----------------- expected `<T as Foo>::Assoc` because of return type
+...
+LL |     ()
+   |     ^^ types differ
+   |
+   = note: expected associated type `<T as Foo>::Assoc`
+                    found unit type `()`
+   = help: consider constraining the associated type `<T as Foo>::Assoc` to `()` or calling a method that returns `<T as Foo>::Assoc`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
+
+error[E0308]: mismatched types
+  --> $DIR/specialization-default-projection.rs:32:5
+   |
+LL | fn monomorphic() -> () {
+   |                     -- expected `()` because of return type
+...
+LL |     generic::<()>()
+   |     ^^^^^^^^^^^^^^^- help: consider using a semicolon here: `;`
+   |     |
+   |     types differ
+   |
+   = note:    expected unit type `()`
+           found associated type `<() as Foo>::Assoc`
+   = help: consider constraining the associated type `<() as Foo>::Assoc` to `()`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/specialization/specialization-default-projection.rs b/tests/ui/specialization/specialization-default-projection.rs
index 7f3ae951287..4f69ccb5974 100644
--- a/tests/ui/specialization/specialization-default-projection.rs
+++ b/tests/ui/specialization/specialization-default-projection.rs
@@ -1,3 +1,7 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 #![feature(specialization)] //~ WARN the feature `specialization` is incomplete
 
 // Make sure we can't project defaulted associated types
diff --git a/tests/ui/specialization/specialization-default-types.stderr b/tests/ui/specialization/specialization-default-types.current.stderr
index 774ac953617..67477f9a6d5 100644
--- a/tests/ui/specialization/specialization-default-types.stderr
+++ b/tests/ui/specialization/specialization-default-types.current.stderr
@@ -1,5 +1,5 @@
 warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/specialization-default-types.rs:5:12
+  --> $DIR/specialization-default-types.rs:9:12
    |
 LL | #![feature(specialization)]
    |            ^^^^^^^^^^^^^^
@@ -9,7 +9,7 @@ LL | #![feature(specialization)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0308]: mismatched types
-  --> $DIR/specialization-default-types.rs:15:9
+  --> $DIR/specialization-default-types.rs:19:9
    |
 LL |     default type Output = Box<T>;
    |     ----------------------------- associated type is `default` and may be overridden
@@ -22,7 +22,7 @@ LL |         Box::new(self)
                        found struct `Box<T>`
 
 error[E0308]: mismatched types
-  --> $DIR/specialization-default-types.rs:25:5
+  --> $DIR/specialization-default-types.rs:29:5
    |
 LL | fn trouble<T>(t: T) -> Box<T> {
    |                        ------ expected `Box<T>` because of return type
diff --git a/tests/ui/specialization/specialization-default-types.next.stderr b/tests/ui/specialization/specialization-default-types.next.stderr
new file mode 100644
index 00000000000..4f7c4765446
--- /dev/null
+++ b/tests/ui/specialization/specialization-default-types.next.stderr
@@ -0,0 +1,39 @@
+warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/specialization-default-types.rs:9:12
+   |
+LL | #![feature(specialization)]
+   |            ^^^^^^^^^^^^^^
+   |
+   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
+   = help: consider using `min_specialization` instead, which is more stable and complete
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+  --> $DIR/specialization-default-types.rs:19:9
+   |
+LL |     default type Output = Box<T>;
+   |     ----------------------------- associated type is `default` and may be overridden
+LL |     default fn generate(self) -> Self::Output {
+   |                                  ------------ expected `<T as Example>::Output` because of return type
+LL |         Box::new(self)
+   |         ^^^^^^^^^^^^^^ types differ
+   |
+   = note: expected associated type `<T as Example>::Output`
+                       found struct `Box<T>`
+
+error[E0308]: mismatched types
+  --> $DIR/specialization-default-types.rs:29:5
+   |
+LL | fn trouble<T>(t: T) -> Box<T> {
+   |                        ------ expected `Box<T>` because of return type
+LL |     Example::generate(t)
+   |     ^^^^^^^^^^^^^^^^^^^^ types differ
+   |
+   = note:       expected struct `Box<T>`
+           found associated type `<T as Example>::Output`
+   = help: consider constraining the associated type `<T as Example>::Output` to `Box<T>`
+   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/specialization/specialization-default-types.rs b/tests/ui/specialization/specialization-default-types.rs
index 346471f11e4..77817abea12 100644
--- a/tests/ui/specialization/specialization-default-types.rs
+++ b/tests/ui/specialization/specialization-default-types.rs
@@ -1,3 +1,7 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 // It should not be possible to use the concrete value of a defaulted
 // associated type in the impl defining it -- otherwise, what happens
 // if it's overridden?
diff --git a/tests/ui/traits/next-solver/specialization-transmute.rs b/tests/ui/traits/next-solver/specialization-transmute.rs
index 376fa22ae19..f1447cd6a9e 100644
--- a/tests/ui/traits/next-solver/specialization-transmute.rs
+++ b/tests/ui/traits/next-solver/specialization-transmute.rs
@@ -10,11 +10,8 @@ trait Default {
 
 impl<T> Default for T {
     default type Id = T;
-    // This will be fixed by #111994
     fn intu(&self) -> &Self::Id {
-        //~^ ERROR type annotations needed
-        //~| ERROR cannot normalize `<T as Default>::Id: '_`
-        self //~ ERROR cannot satisfy
+        self //~ ERROR mismatched types
     }
 }
 
@@ -25,6 +22,7 @@ fn transmute<T: Default<Id = U>, U: Copy>(t: T) -> U {
 use std::num::NonZero;
 
 fn main() {
-    let s = transmute::<u8, Option<NonZero<u8>>>(0); //~ ERROR cannot satisfy
+    let s = transmute::<u8, Option<NonZero<u8>>>(0);
+    //~^ ERROR type mismatch resolving `<u8 as Default>::Id == Option<NonZero<u8>>`
     assert_eq!(s, None);
 }
diff --git a/tests/ui/traits/next-solver/specialization-transmute.stderr b/tests/ui/traits/next-solver/specialization-transmute.stderr
index eeb101911c4..8bd290ea197 100644
--- a/tests/ui/traits/next-solver/specialization-transmute.stderr
+++ b/tests/ui/traits/next-solver/specialization-transmute.stderr
@@ -8,37 +8,32 @@ LL | #![feature(specialization)]
    = help: consider using `min_specialization` instead, which is more stable and complete
    = note: `#[warn(incomplete_features)]` on by default
 
-error: cannot normalize `<T as Default>::Id: '_`
-  --> $DIR/specialization-transmute.rs:14:5
+error[E0308]: mismatched types
+  --> $DIR/specialization-transmute.rs:14:9
    |
 LL |     fn intu(&self) -> &Self::Id {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0282]: type annotations needed
-  --> $DIR/specialization-transmute.rs:14:23
-   |
-LL |     fn intu(&self) -> &Self::Id {
-   |                       ^^^^^^^^^ cannot infer type for reference `&<T as Default>::Id`
-
-error[E0284]: type annotations needed: cannot satisfy `<T as Default>::Id normalizes-to T`
-  --> $DIR/specialization-transmute.rs:17:9
-   |
+   |                       --------- expected `&<T as Default>::Id` because of return type
 LL |         self
-   |         ^^^^ cannot satisfy `<T as Default>::Id normalizes-to T`
+   |         ^^^^ types differ
+   |
+   = note: expected reference `&<T as Default>::Id`
+              found reference `&T`
 
-error[E0284]: type annotations needed: cannot satisfy `<u8 as Default>::Id normalizes-to Option<NonZero<u8>>`
-  --> $DIR/specialization-transmute.rs:28:13
+error[E0271]: type mismatch resolving `<u8 as Default>::Id == Option<NonZero<u8>>`
+  --> $DIR/specialization-transmute.rs:25:50
    |
 LL |     let s = transmute::<u8, Option<NonZero<u8>>>(0);
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot satisfy `<u8 as Default>::Id normalizes-to Option<NonZero<u8>>`
+   |             ------------------------------------ ^ types differ
+   |             |
+   |             required by a bound introduced by this call
    |
 note: required by a bound in `transmute`
-  --> $DIR/specialization-transmute.rs:21:25
+  --> $DIR/specialization-transmute.rs:18:25
    |
 LL | fn transmute<T: Default<Id = U>, U: Copy>(t: T) -> U {
    |                         ^^^^^^ required by this bound in `transmute`
 
-error: aborting due to 4 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0282, E0284.
-For more information about an error, try `rustc --explain E0282`.
+Some errors have detailed explanations: E0271, E0308.
+For more information about an error, try `rustc --explain E0271`.
diff --git a/tests/ui/traits/next-solver/specialization-unconstrained.rs b/tests/ui/traits/next-solver/specialization-unconstrained.rs
index 2bbe7840110..6835c0764d6 100644
--- a/tests/ui/traits/next-solver/specialization-unconstrained.rs
+++ b/tests/ui/traits/next-solver/specialization-unconstrained.rs
@@ -18,5 +18,5 @@ fn test<T: Default<Id = U>, U>() {}
 
 fn main() {
     test::<u32, ()>();
-    //~^ ERROR cannot satisfy `<u32 as Default>::Id normalizes-to ()`
+    //~^ ERROR type mismatch resolving `<u32 as Default>::Id == ()`
 }
diff --git a/tests/ui/traits/next-solver/specialization-unconstrained.stderr b/tests/ui/traits/next-solver/specialization-unconstrained.stderr
index e1d785b554b..1bcf5eddb5b 100644
--- a/tests/ui/traits/next-solver/specialization-unconstrained.stderr
+++ b/tests/ui/traits/next-solver/specialization-unconstrained.stderr
@@ -8,11 +8,11 @@ LL | #![feature(specialization)]
    = help: consider using `min_specialization` instead, which is more stable and complete
    = note: `#[warn(incomplete_features)]` on by default
 
-error[E0284]: type annotations needed: cannot satisfy `<u32 as Default>::Id normalizes-to ()`
-  --> $DIR/specialization-unconstrained.rs:20:5
+error[E0271]: type mismatch resolving `<u32 as Default>::Id == ()`
+  --> $DIR/specialization-unconstrained.rs:20:12
    |
 LL |     test::<u32, ()>();
-   |     ^^^^^^^^^^^^^^^^^ cannot satisfy `<u32 as Default>::Id normalizes-to ()`
+   |            ^^^ types differ
    |
 note: required by a bound in `test`
   --> $DIR/specialization-unconstrained.rs:17:20
@@ -22,4 +22,4 @@ LL | fn test<T: Default<Id = U>, U>() {}
 
 error: aborting due to 1 previous error; 1 warning emitted
 
-For more information about this error, try `rustc --explain E0284`.
+For more information about this error, try `rustc --explain E0271`.