AST lowering: More robustly deal with relaxed bounds

9 files changed, 43 insertions, 60 deletions

diff --git a/tests/ui/associated-item/missing-associated_item_or_field_def_ids.rs b/tests/ui/associated-item/missing-associated_item_or_field_def_ids.rs
index b90bb9ea4dd..18c71e5c744 100644
--- a/tests/ui/associated-item/missing-associated_item_or_field_def_ids.rs
+++ b/tests/ui/associated-item/missing-associated_item_or_field_def_ids.rs
@@ -1,8 +1,7 @@
 // Regression test for <https://github.com/rust-lang/rust/issues/137554>.
 
 fn main() -> dyn Iterator + ?Iterator::advance_by(usize) {
-    //~^ ERROR `?Trait` is not permitted in trait object types
-    //~| ERROR expected trait, found associated function `Iterator::advance_by`
-    //~| ERROR the value of the associated type `Item` in `Iterator` must be specified
+    //~^ ERROR expected trait, found associated function `Iterator::advance_by`
+    //~| ERROR `?Trait` is not permitted in trait object types
     todo!()
 }
diff --git a/tests/ui/associated-item/missing-associated_item_or_field_def_ids.stderr b/tests/ui/associated-item/missing-associated_item_or_field_def_ids.stderr
index 7f0fbc800ed..6ec8e01c78d 100644
--- a/tests/ui/associated-item/missing-associated_item_or_field_def_ids.stderr
+++ b/tests/ui/associated-item/missing-associated_item_or_field_def_ids.stderr
@@ -1,25 +1,19 @@
-error[E0658]: `?Trait` is not permitted in trait object types
-  --> $DIR/missing-associated_item_or_field_def_ids.rs:3:29
-   |
-LL | fn main() -> dyn Iterator + ?Iterator::advance_by(usize) {
-   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0404]: expected trait, found associated function `Iterator::advance_by`
   --> $DIR/missing-associated_item_or_field_def_ids.rs:3:30
    |
 LL | fn main() -> dyn Iterator + ?Iterator::advance_by(usize) {
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not a trait
 
-error[E0191]: the value of the associated type `Item` in `Iterator` must be specified
-  --> $DIR/missing-associated_item_or_field_def_ids.rs:3:18
+error[E0658]: `?Trait` is not permitted in trait object types
+  --> $DIR/missing-associated_item_or_field_def_ids.rs:3:29
    |
 LL | fn main() -> dyn Iterator + ?Iterator::advance_by(usize) {
-   |                  ^^^^^^^^ help: specify the associated type: `Iterator<Item = Type>`
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0191, E0404, E0658.
-For more information about an error, try `rustc --explain E0191`.
+Some errors have detailed explanations: E0404, E0658.
+For more information about an error, try `rustc --explain E0404`.
diff --git a/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.rs b/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.rs
index f6b749a5100..9e0a86abb2e 100644
--- a/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.rs
+++ b/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.rs
@@ -6,7 +6,6 @@ trait Tr {
 
 fn main() {
     let _: dyn Tr + ?Foo<Assoc = ()>;
-    //~^ ERROR: `?Trait` is not permitted in trait object types
-    //~| ERROR: cannot find trait `Foo` in this scope
-    //~| ERROR: the value of the associated type `Item` in `Tr` must be specified
+    //~^ ERROR: cannot find trait `Foo` in this scope
+    //~| ERROR: `?Trait` is not permitted in trait object types
 }
diff --git a/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.stderr b/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.stderr
index f31a1de76a7..bd83c1a9ea8 100644
--- a/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.stderr
+++ b/tests/ui/associated-types/avoid-getting-associated-items-of-undefined-trait.stderr
@@ -1,28 +1,19 @@
-error[E0658]: `?Trait` is not permitted in trait object types
-  --> $DIR/avoid-getting-associated-items-of-undefined-trait.rs:8:21
-   |
-LL |     let _: dyn Tr + ?Foo<Assoc = ()>;
-   |                     ^^^^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0405]: cannot find trait `Foo` in this scope
   --> $DIR/avoid-getting-associated-items-of-undefined-trait.rs:8:22
    |
 LL |     let _: dyn Tr + ?Foo<Assoc = ()>;
    |                      ^^^ not found in this scope
 
-error[E0191]: the value of the associated type `Item` in `Tr` must be specified
-  --> $DIR/avoid-getting-associated-items-of-undefined-trait.rs:8:16
+error[E0658]: `?Trait` is not permitted in trait object types
+  --> $DIR/avoid-getting-associated-items-of-undefined-trait.rs:8:21
    |
-LL |     type Item;
-   |     --------- `Item` defined here
-...
 LL |     let _: dyn Tr + ?Foo<Assoc = ()>;
-   |                ^^ help: specify the associated type: `Tr<Item = Type>`
+   |                     ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0191, E0405, E0658.
-For more information about an error, try `rustc --explain E0191`.
+Some errors have detailed explanations: E0405, E0658.
+For more information about an error, try `rustc --explain E0405`.
diff --git a/tests/ui/feature-gates/feature-gate-more-maybe-bounds.stderr b/tests/ui/feature-gates/feature-gate-more-maybe-bounds.stderr
index 729df4eb37c..f52532a035b 100644
--- a/tests/ui/feature-gates/feature-gate-more-maybe-bounds.stderr
+++ b/tests/ui/feature-gates/feature-gate-more-maybe-bounds.stderr
@@ -4,24 +4,23 @@ error[E0658]: `?Trait` is not permitted in supertraits
 LL | trait Trait3: ?Trait1 {}
    |               ^^^^^^^
    |
-   = note: traits are `?Trait1` by default
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0658]: `?Trait` is not permitted in trait object types
-  --> $DIR/feature-gate-more-maybe-bounds.rs:10:28
+error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
+  --> $DIR/feature-gate-more-maybe-bounds.rs:7:26
    |
-LL | fn foo(_: Box<dyn Trait1 + ?Trait2>) {}
-   |                            ^^^^^^^
+LL | trait Trait4 where Self: ?Trait1 {}
+   |                          ^^^^^^^
    |
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/feature-gate-more-maybe-bounds.rs:7:26
+error[E0658]: `?Trait` is not permitted in trait object types
+  --> $DIR/feature-gate-more-maybe-bounds.rs:10:28
    |
-LL | trait Trait4 where Self: ?Trait1 {}
-   |                          ^^^^^^^
+LL | fn foo(_: Box<dyn Trait1 + ?Trait2>) {}
+   |                            ^^^^^^^
    |
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
diff --git a/tests/ui/sized-hierarchy/default-supertrait.stderr b/tests/ui/sized-hierarchy/default-supertrait.stderr
index de23936b900..0cb4f346a63 100644
--- a/tests/ui/sized-hierarchy/default-supertrait.stderr
+++ b/tests/ui/sized-hierarchy/default-supertrait.stderr
@@ -4,9 +4,9 @@ error[E0658]: `?Trait` is not permitted in supertraits
 LL | trait NegSized: ?Sized { }
    |                 ^^^^^^
    |
-   = note: traits are `?Sized` by default
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: traits are `?Sized` by default
 
 error[E0658]: `?Trait` is not permitted in supertraits
   --> $DIR/default-supertrait.rs:13:21
@@ -14,7 +14,6 @@ error[E0658]: `?Trait` is not permitted in supertraits
 LL | trait NegMetaSized: ?MetaSized { }
    |                     ^^^^^^^^^^
    |
-   = note: traits are `?MetaSized` by default
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
@@ -24,7 +23,6 @@ error[E0658]: `?Trait` is not permitted in supertraits
 LL | trait NegPointeeSized: ?PointeeSized { }
    |                        ^^^^^^^^^^^^^
    |
-   = note: traits are `?PointeeSized` by default
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
diff --git a/tests/ui/traits/maybe-trait-bounds-forbidden-locations.stderr b/tests/ui/traits/maybe-trait-bounds-forbidden-locations.stderr
index bd0baa580bd..5c4100d0e26 100644
--- a/tests/ui/traits/maybe-trait-bounds-forbidden-locations.stderr
+++ b/tests/ui/traits/maybe-trait-bounds-forbidden-locations.stderr
@@ -4,9 +4,9 @@ error[E0658]: `?Trait` is not permitted in supertraits
 LL | trait Tr: ?Sized {}
    |           ^^^^^^
    |
-   = note: traits are `?Sized` by default
    = help: add `#![feature(more_maybe_bounds)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: traits are `?Sized` by default
 
 error[E0658]: `?Trait` is not permitted in trait object types
   --> $DIR/maybe-trait-bounds-forbidden-locations.rs:13:20
diff --git a/tests/ui/unsized/maybe-bounds-where.rs b/tests/ui/unsized/relaxed-bounds-invalid-places.rs
index 4c4141631a7..ce3f35608be 100644
--- a/tests/ui/unsized/maybe-bounds-where.rs
+++ b/tests/ui/unsized/relaxed-bounds-invalid-places.rs
@@ -1,3 +1,6 @@
+// Test that relaxed bounds can only be placed on type parameters defined by the closest item
+// (ignoring relaxed bounds inside `impl Trait` and in associated type defs here).
+
 struct S1<T>(T) where (T): ?Sized;
 //~^ ERROR `?Trait` bounds are only permitted at the point where a type parameter is declared
 
diff --git a/tests/ui/unsized/maybe-bounds-where.stderr b/tests/ui/unsized/relaxed-bounds-invalid-places.stderr
index fb6d37c2966..3287eb8d1e9 100644
--- a/tests/ui/unsized/maybe-bounds-where.stderr
+++ b/tests/ui/unsized/relaxed-bounds-invalid-places.stderr
@@ -1,5 +1,5 @@
 error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:1:28
+  --> $DIR/relaxed-bounds-invalid-places.rs:4:28
    |
 LL | struct S1<T>(T) where (T): ?Sized;
    |                            ^^^^^^
@@ -8,7 +8,7 @@ LL | struct S1<T>(T) where (T): ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:4:27
+  --> $DIR/relaxed-bounds-invalid-places.rs:7:27
    |
 LL | struct S2<T>(T) where u8: ?Sized;
    |                           ^^^^^^
@@ -17,7 +17,7 @@ LL | struct S2<T>(T) where u8: ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:7:35
+  --> $DIR/relaxed-bounds-invalid-places.rs:10:35
    |
 LL | struct S3<T>(T) where &'static T: ?Sized;
    |                                   ^^^^^^
@@ -26,7 +26,7 @@ LL | struct S3<T>(T) where &'static T: ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:12:34
+  --> $DIR/relaxed-bounds-invalid-places.rs:15:34
    |
 LL | struct S4<T>(T) where for<'a> T: ?Trait<'a>;
    |                                  ^^^^^^^^^^
@@ -35,7 +35,7 @@ LL | struct S4<T>(T) where for<'a> T: ?Trait<'a>;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:21:21
+  --> $DIR/relaxed-bounds-invalid-places.rs:24:21
    |
 LL |     fn f() where T: ?Sized {}
    |                     ^^^^^^
@@ -44,13 +44,13 @@ LL |     fn f() where T: ?Sized {}
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error: relaxing a default bound only does something for `?Sized`; all other traits are not bound by default
-  --> $DIR/maybe-bounds-where.rs:12:34
+  --> $DIR/relaxed-bounds-invalid-places.rs:15:34
    |
 LL | struct S4<T>(T) where for<'a> T: ?Trait<'a>;
    |                                  ^^^^^^^^^^
 
 error[E0203]: type parameter has more than one relaxed default bound, only one is supported
-  --> $DIR/maybe-bounds-where.rs:16:33
+  --> $DIR/relaxed-bounds-invalid-places.rs:19:33
    |
 LL | struct S5<T>(*const T) where T: ?Trait<'static> + ?Sized;
    |                                 ^^^^^^^^^^^^^^^   ^^^^^^
@@ -59,7 +59,7 @@ LL | struct S5<T>(*const T) where T: ?Trait<'static> + ?Sized;
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error: relaxing a default bound only does something for `?Sized`; all other traits are not bound by default
-  --> $DIR/maybe-bounds-where.rs:16:33
+  --> $DIR/relaxed-bounds-invalid-places.rs:19:33
    |
 LL | struct S5<T>(*const T) where T: ?Trait<'static> + ?Sized;
    |                                 ^^^^^^^^^^^^^^^