Add more tests for generic associated type bounds

src/test/ui/generic-associated-types/generic-associated-type-bounds.rs

@@ -0,0 +1,35 @@
+// run-pass
+
+#![allow(incomplete_features)]
+#![feature(generic_associated_types)]
+
+pub trait X {
+    type Y<'a>;
+    fn m(&self) -> Self::Y<'_>;
+}
+
+impl X for () {
+    type Y<'a> = &'a ();
+
+    fn m(&self) -> Self::Y<'_> {
+        self
+    }
+}
+
+fn f(x: &impl for<'a> X<Y<'a> = &'a ()>) -> &() {
+    x.m()
+}
+
+fn g<T: for<'a> X<Y<'a> = &'a ()>>(x: &T) -> &() {
+    x.m()
+}
+
+fn h(x: &()) -> &() {
+    x.m()
+}
+
+fn main() {
+    f(&());
+    g(&());
+    h(&());
+}

src/test/ui/generic-associated-types/issue-76535.rs

@@ -1,11 +1,11 @@
 #![feature(generic_associated_types)]
- //~^ WARNING the feature
+//~^ WARNING the feature
 
 pub trait SubTrait {}
 
 pub trait SuperTrait {
     type SubType<'a>: SubTrait;
-      //~^ ERROR missing generics for associated
+    //~^ ERROR missing generics for associated
 
     fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
 }
@@ -36,6 +36,4 @@ impl SuperTrait for SuperStruct {
 
 fn main() {
     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
-      //~^ ERROR the trait
-      //~| ERROR the trait
 }

src/test/ui/generic-associated-types/issue-76535.stderr

@@ -23,41 +23,6 @@ help: use angle brackets to add missing lifetime argument
 LL |     type SubType<'a><'a>: SubTrait;
    |                 ^^^^
 
-error[E0038]: the trait `SuperTrait` cannot be made into an object
-  --> $DIR/issue-76535.rs:38:14
-   |
-LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
-   |
-   = help: consider moving `get_sub` to another trait
-note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/issue-76535.rs:10:37
-   |
-LL | pub trait SuperTrait {
-   |           ---------- this trait cannot be made into an object...
-...
-LL |     fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
-   |                                     ^^^^^^^^^^^^^^^^^ ...because method `get_sub` references the `Self` type in its return type
+error: aborting due to previous error; 1 warning emitted
 
-error[E0038]: the trait `SuperTrait` cannot be made into an object
-  --> $DIR/issue-76535.rs:38:57
-   |
-LL |     let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
-   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
-   |
-   = help: consider moving `get_sub` to another trait
-note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/issue-76535.rs:10:37
-   |
-LL | pub trait SuperTrait {
-   |           ---------- this trait cannot be made into an object...
-...
-LL |     fn get_sub<'a>(&'a mut self) -> Self::SubType<'a>;
-   |                                     ^^^^^^^^^^^^^^^^^ ...because method `get_sub` references the `Self` type in its return type
-   = note: required because of the requirements on the impl of `CoerceUnsized<Box<dyn SuperTrait<SubType = SubStruct<'_>>>>` for `Box<SuperStruct>`
-   = note: required by cast to type `Box<dyn SuperTrait<SubType = SubStruct<'_>>>`
-
-error: aborting due to 3 previous errors; 1 warning emitted
-
-Some errors have detailed explanations: E0038, E0107.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0107`.

src/test/ui/generic-associated-types/issue-79422.rs

@@ -19,7 +19,7 @@ impl<'a, T> RefCont<'a, T> for Box<T> {
 
 trait MapLike<K, V> {
     type VRefCont<'a>: RefCont<'a, V>;
-      //~^ ERROR missing generics
+    //~^ ERROR missing generics
     fn get<'a>(&'a self, key: &K) -> Option<Self::VRefCont<'a>>;
 }
 
@@ -42,6 +42,5 @@ impl<K, V: Default> MapLike<K, V> for Source {
 fn main() {
     let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
-      //~^ ERROR the trait
-      //~^^^ ERROR the trait
+    //~^^ ERROR type mismatch resolving
 }

src/test/ui/generic-associated-types/issue-79422.stderr

@@ -14,41 +14,17 @@ help: use angle brackets to add missing lifetime argument
 LL |     type VRefCont<'a><'a>: RefCont<'a, V>;
    |                  ^^^^
 
-error[E0038]: the trait `MapLike` cannot be made into an object
-  --> $DIR/issue-79422.rs:44:12
-   |
-LL |         as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
-   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
-   |
-   = help: consider moving `get` to another trait
-note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/issue-79422.rs:23:38
-   |
-LL | trait MapLike<K, V> {
-   |       ------- this trait cannot be made into an object...
-...
-LL |     fn get<'a>(&'a self, key: &K) -> Option<Self::VRefCont<'a>>;
-   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...because method `get` references the `Self` type in its return type
-
-error[E0038]: the trait `MapLike` cannot be made into an object
+error[E0271]: type mismatch resolving `<BTreeMap<u8, u8> as MapLike<u8, u8>>::VRefCont<'static> == (dyn RefCont<'_, u8> + 'static)`
   --> $DIR/issue-79422.rs:43:13
    |
 LL |     let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected trait object `dyn RefCont`, found reference
    |
-   = help: consider moving `get` to another trait
-note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/issue-79422.rs:23:38
-   |
-LL | trait MapLike<K, V> {
-   |       ------- this trait cannot be made into an object...
-...
-LL |     fn get<'a>(&'a self, key: &K) -> Option<Self::VRefCont<'a>>;
-   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ ...because method `get` references the `Self` type in its return type
-   = note: required because of the requirements on the impl of `CoerceUnsized<Box<dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>>>` for `Box<BTreeMap<u8, u8>>`
-   = note: required by cast to type `Box<dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>>`
+   = note: expected trait object `(dyn RefCont<'_, u8> + 'static)`
+                 found reference `&'static u8`
+   = note: required for the cast to the object type `dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>`
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0038, E0107.
-For more information about an error, try `rustc --explain E0038`.
+Some errors have detailed explanations: E0107, E0271.
+For more information about an error, try `rustc --explain E0107`.

src/test/ui/generic-associated-types/projection-type-lifetime-mismatch.rs

@@ -0,0 +1,36 @@
+#![allow(incomplete_features)]
+#![feature(generic_associated_types)]
+
+pub trait X {
+    type Y<'a>;
+    fn m(&self) -> Self::Y<'_>;
+}
+
+impl X for () {
+    type Y<'a> = &'a ();
+
+    fn m(&self) -> Self::Y<'_> {
+        self
+    }
+}
+
+fn f(x: &impl for<'a> X<Y<'a> = &'a ()>) -> &'static () {
+    x.m()
+    //~^ ERROR explicit lifetime required
+}
+
+fn g<T: for<'a> X<Y<'a> = &'a ()>>(x: &T) -> &'static () {
+    x.m()
+    //~^ ERROR explicit lifetime required
+}
+
+fn h(x: &()) -> &'static () {
+    x.m()
+    //~^ ERROR explicit lifetime required
+}
+
+fn main() {
+    f(&());
+    g(&());
+    h(&());
+}

src/test/ui/generic-associated-types/projection-type-lifetime-mismatch.stderr

@@ -0,0 +1,27 @@
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/projection-type-lifetime-mismatch.rs:18:5
+   |
+LL | fn f(x: &impl for<'a> X<Y<'a> = &'a ()>) -> &'static () {
+   |         ------------------------------- help: add explicit lifetime `'static` to the type of `x`: `&'static impl for<'a> X<Y<'a> = &'a ()>`
+LL |     x.m()
+   |     ^^^^^ lifetime `'static` required
+
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/projection-type-lifetime-mismatch.rs:23:5
+   |
+LL | fn g<T: for<'a> X<Y<'a> = &'a ()>>(x: &T) -> &'static () {
+   |                                       -- help: add explicit lifetime `'static` to the type of `x`: `&'static T`
+LL |     x.m()
+   |     ^^^^^ lifetime `'static` required
+
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/projection-type-lifetime-mismatch.rs:28:5
+   |
+LL | fn h(x: &()) -> &'static () {
+   |         --- help: add explicit lifetime `'static` to the type of `x`: `&'static ()`
+LL |     x.m()
+   |     ^^^^^ lifetime `'static` required
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0621`.

src/test/ui/generic-associated-types/unsatified-item-lifetime-bound.rs

@@ -0,0 +1,28 @@
+#![allow(incomplete_features)]
+#![feature(generic_associated_types)]
+
+pub trait X {
+    type Y<'a: 'static>;
+    //~^ WARNING unnecessary lifetime parameter
+}
+
+impl X for () {
+    type Y<'a> = &'a ();
+}
+
+struct B<'a, T: for<'r> X<Y<'r> = &'r ()>> {
+    f: <T as X>::Y<'a>,
+    //~^ ERROR lifetime bound not satisfied
+}
+
+struct C<'a, T: X> {
+    f: <T as X>::Y<'a>,
+    //~^ ERROR lifetime bound not satisfied
+}
+
+struct D<'a> {
+    f: <() as X>::Y<'a>,
+    //~^ ERROR lifetime bound not satisfied
+}
+
+fn main() {}

src/test/ui/generic-associated-types/unsatified-item-lifetime-bound.stderr

@@ -0,0 +1,50 @@
+warning: unnecessary lifetime parameter `'a`
+  --> $DIR/unsatified-item-lifetime-bound.rs:5:12
+   |
+LL |     type Y<'a: 'static>;
+   |            ^^^^^^^^^^^
+   |
+   = help: you can use the `'static` lifetime directly, in place of `'a`
+
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/unsatified-item-lifetime-bound.rs:14:8
+   |
+LL |     f: <T as X>::Y<'a>,
+   |        ^^^^^^^^^^^^^^^
+   |
+note: lifetime parameter instantiated with the lifetime `'a` as defined on the struct at 13:10
+  --> $DIR/unsatified-item-lifetime-bound.rs:13:10
+   |
+LL | struct B<'a, T: for<'r> X<Y<'r> = &'r ()>> {
+   |          ^^
+   = note: but lifetime parameter must outlive the static lifetime
+
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/unsatified-item-lifetime-bound.rs:19:8
+   |
+LL |     f: <T as X>::Y<'a>,
+   |        ^^^^^^^^^^^^^^^
+   |
+note: lifetime parameter instantiated with the lifetime `'a` as defined on the struct at 18:10
+  --> $DIR/unsatified-item-lifetime-bound.rs:18:10
+   |
+LL | struct C<'a, T: X> {
+   |          ^^
+   = note: but lifetime parameter must outlive the static lifetime
+
+error[E0478]: lifetime bound not satisfied
+  --> $DIR/unsatified-item-lifetime-bound.rs:24:8
+   |
+LL |     f: <() as X>::Y<'a>,
+   |        ^^^^^^^^^^^^^^^^
+   |
+note: lifetime parameter instantiated with the lifetime `'a` as defined on the struct at 23:10
+  --> $DIR/unsatified-item-lifetime-bound.rs:23:10
+   |
+LL | struct D<'a> {
+   |          ^^
+   = note: but lifetime parameter must outlive the static lifetime
+
+error: aborting due to 3 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0478`.