Rollup merge of #137000 - compiler-errors:deeply-normalize-item-bounds, r=lcnr

Deeply normalize item bounds in new solver

Built on #136863.

Fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/142.
Fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/151.

cc https://github.com/rust-lang/trait-system-refactor-initiative/issues/116

First commit reworks candidate preference for projection bounds to prefer param-env projection clauses even if the corresponding trait ref doesn't come from the param-env.

Second commit adjusts the associated type item bounds check to deeply normalize in the new solver. This causes some test fallout which I will point out.

r? lcnr

9 files changed, 65 insertions, 25 deletions

diff --git a/tests/ui/generic-associated-types/issue-91883.stderr b/tests/ui/generic-associated-types/issue-91883.current.stderr
index ac636ebb648..0741cf9581d 100644
--- a/tests/ui/generic-associated-types/issue-91883.stderr
+++ b/tests/ui/generic-associated-types/issue-91883.current.stderr
@@ -1,5 +1,5 @@
 error[E0478]: lifetime bound not satisfied
-  --> $DIR/issue-91883.rs:30:24
+  --> $DIR/issue-91883.rs:34:24
    |
 LL |     type Cursor<'tx>: Cursor<'tx>
    |     ----------------------------- definition of `Cursor` from trait
@@ -8,12 +8,12 @@ LL |     type Cursor<'tx> = CursorImpl<'tx>;
    |                        ^^^^^^^^^^^^^^^
    |
 note: lifetime parameter instantiated with the lifetime `'db` as defined here
-  --> $DIR/issue-91883.rs:29:6
+  --> $DIR/issue-91883.rs:33:6
    |
 LL | impl<'db> Transaction<'db> for TransactionImpl<'db> {
    |      ^^^
 note: but lifetime parameter must outlive the lifetime `'tx` as defined here
-  --> $DIR/issue-91883.rs:30:17
+  --> $DIR/issue-91883.rs:34:17
    |
 LL |     type Cursor<'tx> = CursorImpl<'tx>;
    |                 ^^^
diff --git a/tests/ui/generic-associated-types/issue-91883.next.stderr b/tests/ui/generic-associated-types/issue-91883.next.stderr
new file mode 100644
index 00000000000..b3ed2d81b63
--- /dev/null
+++ b/tests/ui/generic-associated-types/issue-91883.next.stderr
@@ -0,0 +1,20 @@
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/issue-91883.rs:34:24
+   |
+LL |     type Cursor<'tx> = CursorImpl<'tx>;
+   |                        ^^^^^^^^^^^^^^^
+   |
+note: lifetime parameter instantiated with the lifetime `'db` as defined here
+  --> $DIR/issue-91883.rs:33:6
+   |
+LL | impl<'db> Transaction<'db> for TransactionImpl<'db> {
+   |      ^^^
+note: but lifetime parameter must outlive the lifetime `'tx` as defined here
+  --> $DIR/issue-91883.rs:34:17
+   |
+LL |     type Cursor<'tx> = CursorImpl<'tx>;
+   |                 ^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0478`.
diff --git a/tests/ui/generic-associated-types/issue-91883.rs b/tests/ui/generic-associated-types/issue-91883.rs
index e870e08a3a2..d31e1736cf2 100644
--- a/tests/ui/generic-associated-types/issue-91883.rs
+++ b/tests/ui/generic-associated-types/issue-91883.rs
@@ -1,3 +1,7 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
 use std::fmt::Debug;
 use std::marker::PhantomData;
 
diff --git a/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs b/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
index c1a78bc2388..1bbff839ffa 100644
--- a/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
+++ b/tests/ui/impl-trait/in-trait/default-body-with-rpit.rs
@@ -1,5 +1,8 @@
 //@ edition:2021
 //@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
 
 use std::fmt::Debug;
 
diff --git a/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs
index 10c2a811243..6954a7d8067 100644
--- a/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs
+++ b/tests/ui/impl-trait/in-trait/nested-rpitit-bounds.rs
@@ -1,4 +1,7 @@
 //@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
 
 use std::ops::Deref;
 
diff --git a/tests/ui/traits/const-traits/predicate-entailment-passes.rs b/tests/ui/traits/const-traits/predicate-entailment-passes.rs
index 9c8d5a5e3f6..28ae21891f3 100644
--- a/tests/ui/traits/const-traits/predicate-entailment-passes.rs
+++ b/tests/ui/traits/const-traits/predicate-entailment-passes.rs
@@ -6,32 +6,21 @@
 #[const_trait] trait Bar {}
 impl const Bar for () {}
 
-
 #[const_trait] trait TildeConst {
-    type Bar<T> where T: ~const Bar;
-
     fn foo<T>() where T: ~const Bar;
 }
 impl TildeConst for () {
-    type Bar<T> = () where T: Bar;
-
     fn foo<T>() where T: Bar {}
 }
 
 
 #[const_trait] trait AlwaysConst {
-    type Bar<T> where T: const Bar;
-
     fn foo<T>() where T: const Bar;
 }
 impl AlwaysConst for i32 {
-    type Bar<T> = () where T: Bar;
-
     fn foo<T>() where T: Bar {}
 }
 impl const AlwaysConst for u32 {
-    type Bar<T> = () where T: ~const Bar;
-
     fn foo<T>() where T: ~const Bar {}
 }
 
diff --git a/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
index 1d42dbdfe00..294fa0d7613 100644
--- a/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
+++ b/tests/ui/traits/next-solver/coherence/trait_ref_is_knowable-norm-overflow.stderr
@@ -1,18 +1,8 @@
-error[E0275]: overflow evaluating the requirement `<T as Overflow>::Assoc: Sized`
+error[E0275]: overflow evaluating the requirement `<T as Overflow>::Assoc == _`
   --> $DIR/trait_ref_is_knowable-norm-overflow.rs:10:18
    |
 LL |     type Assoc = <T as Overflow>::Assoc;
    |                  ^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: required by a bound in `Overflow::Assoc`
-  --> $DIR/trait_ref_is_knowable-norm-overflow.rs:7:5
-   |
-LL |     type Assoc;
-   |     ^^^^^^^^^^^ required by this bound in `Overflow::Assoc`
-help: consider relaxing the implicit `Sized` restriction
-   |
-LL |     type Assoc: ?Sized;
-   |               ++++++++
 
 error[E0119]: conflicting implementations of trait `Trait`
   --> $DIR/trait_ref_is_knowable-norm-overflow.rs:18:1
diff --git a/tests/ui/traits/next-solver/gat-wf.rs b/tests/ui/traits/next-solver/gat-wf.rs
new file mode 100644
index 00000000000..ff6e2665ef3
--- /dev/null
+++ b/tests/ui/traits/next-solver/gat-wf.rs
@@ -0,0 +1,16 @@
+//@ compile-flags: -Znext-solver
+
+// Make sure that, like the old trait solver, we end up requiring that the WC of
+// impl GAT matches that of the trait. This is not a restriction that we *need*,
+// but is a side-effect of registering the where clauses when normalizing the GAT
+// when proving it satisfies its item bounds.
+
+trait Foo {
+    type T<'a>: Sized where Self: 'a;
+}
+
+impl Foo for &() {
+    type T<'a> = (); //~ the type `&()` does not fulfill the required lifetime
+}
+
+fn main() {}
diff --git a/tests/ui/traits/next-solver/gat-wf.stderr b/tests/ui/traits/next-solver/gat-wf.stderr
new file mode 100644
index 00000000000..620bca77e4b
--- /dev/null
+++ b/tests/ui/traits/next-solver/gat-wf.stderr
@@ -0,0 +1,15 @@
+error[E0477]: the type `&()` does not fulfill the required lifetime
+  --> $DIR/gat-wf.rs:13:18
+   |
+LL |     type T<'a> = ();
+   |                  ^^
+   |
+note: type must outlive the lifetime `'a` as defined here
+  --> $DIR/gat-wf.rs:13:12
+   |
+LL |     type T<'a> = ();
+   |            ^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0477`.