Code
trait Factory {
fn create() -> Box<dyn Factory>;
//~^ ERROR the trait `Factory` is not dyn compatible
}
fn use_factory(_: &dyn Factory) {}
// The diagnostic explains the mechanical rule, but not that a receiver-less constructor cannot be
// selected from a trait object or that `where Self: Sized` makes this intent explicit.
fn main() {}Current output
error[E0038]: the trait `Factory` is not dyn compatible
--> $DIR/static-constructor-prevents-dyn-no-api-guidance.rs:12:20
|
LL | fn use_factory(_: &dyn Factory) {}
| ^^^^^^^^^^^ `Factory` is not dyn compatible
|
note: for a trait to be dyn compatible it needs to allow building a vtable
for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
--> $DIR/static-constructor-prevents-dyn-no-api-guidance.rs:8:8
|
LL | trait Factory {
| ------- this trait is not dyn compatible...
LL | fn create() -> Box<dyn Factory>;
| ^^^^^^ ...because associated function `create` has no `self` parameter
help: consider turning `create` into a method by giving it a `&self` argument
|
LL | fn create(&self) -> Box<dyn Factory>;
| +++++
help: alternatively, consider constraining `create` so it does not apply to trait objects
|
LL | fn create() -> Box<dyn Factory> where Self: Sized;
| +++++++++++++++++Desired output
error[E0038]: the trait `Factory` is not dyn compatible
--> $DIR/static-constructor-prevents-dyn-no-api-guidance.rs:12:20
|
LL | fn use_factory(_: &dyn Factory) {}
| ^^^^^^^^^^^ `Factory` is not dyn compatible
|
note: for a trait to be dyn compatible it needs to allow building a vtable
for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
--> $DIR/static-constructor-prevents-dyn-no-api-guidance.rs:8:8
|
LL | trait Factory {
| ------- this trait is not dyn compatible...
LL | fn create() -> Box<dyn Factory>;
| ^^^^^^ ...because associated function `create` has no `self` parameter
help: consider turning `create` into a method by giving it a `&self` argument, so that it is accessible through the trait object's vtable
|
LL | fn create(&self) -> Box<dyn Factory>;
| +++++
help: alternatively, consider constraining `create` so it is explicitly marked as not applying to trait objects
|
LL | fn create() -> Box<dyn Factory> where Self: Sized;
| +++++++++++++++++Rationale and extra context
The wording can be iterated on, let's just try to add more context.
Other cases
Rust Version
Anything else?
No response
Code
Current output
Desired output
Rationale and extra context
The wording can be iterated on, let's just try to add more context.
Other cases
Rust Version
Anything else?
No response