rust/tests/ui/issues/issue-34373.stderr
2024-02-01 16:18:03 +01:00

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error[E0391]: cycle detected when computing type of `Foo::T`
--> $DIR/issue-34373.rs:7:30
|
LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
| ^^^^^^^^^^
|
note: ...which requires expanding type alias `DefaultFoo`...
--> $DIR/issue-34373.rs:10:19
|
LL | type DefaultFoo = Foo;
| ^^^
= note: ...which again requires computing type of `Foo::T`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/issue-34373.rs:1:1
|
LL | / #![allow(warnings)]
LL | |
LL | | trait Trait<T> {
LL | | fn foo(_: T) {}
... |
LL | | fn main() {
LL | | }
| |_^
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error[E0038]: the trait `Trait` cannot be made into an object
--> $DIR/issue-34373.rs:7:24
|
LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
| ^^^^^^^^^^^^^^^^^ `Trait` cannot be made into an object
|
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-34373.rs:4:8
|
LL | trait Trait<T> {
| ----- this trait cannot be made into an object...
LL | fn foo(_: T) {}
| ^^^ ...because associated function `foo` has no `self` parameter
help: consider turning `foo` into a method by giving it a `&self` argument
|
LL | fn foo(&self, _: T) {}
| ++++++
help: alternatively, consider constraining `foo` so it does not apply to trait objects
|
LL | fn foo(_: T) where Self: Sized {}
| +++++++++++++++++
error[E0392]: type parameter `T` is never used
--> $DIR/issue-34373.rs:7:16
|
LL | pub struct Foo<T = Box<Trait<DefaultFoo>>>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ unused type parameter
|
= help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
= help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead
error: aborting due to 3 previous errors
Some errors have detailed explanations: E0038, E0391, E0392.
For more information about an error, try `rustc --explain E0038`.