mirror of
https://github.com/rust-lang/rust.git
synced 2024-12-14 17:48:10 +00:00
8c04999226
When we encounter a `dyn Trait` that isn't object safe, look for its
implementors. If there's one, mention using it directly If there are
less than 9, mention the possibility of creating a new enum and using
that instead.
Account for object unsafe `impl Trait on dyn Trait {}`. Make a
distinction between public and sealed traits.
Fix #80194.
63 lines
2.6 KiB
Plaintext
63 lines
2.6 KiB
Plaintext
error[E0308]: `match` arms have incompatible types
|
|
--> $DIR/wf-unsafe-trait-obj-match.rs:23:17
|
|
|
|
|
LL | / match opt() {
|
|
LL | | Some(()) => &S,
|
|
| | -- this is found to be of type `&S`
|
|
LL | | None => &R,
|
|
| | ^^ expected `&S`, found `&R`
|
|
LL | | }
|
|
| |_____- `match` arms have incompatible types
|
|
|
|
|
= note: expected reference `&S`
|
|
found reference `&R`
|
|
help: consider using a semicolon here, but this will discard any values in the match arms
|
|
|
|
|
LL | };
|
|
| +
|
|
|
|
error[E0038]: the trait `Trait` cannot be made into an object
|
|
--> $DIR/wf-unsafe-trait-obj-match.rs:26:21
|
|
|
|
|
LL | Some(()) => &S,
|
|
| ^^ `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/wf-unsafe-trait-obj-match.rs:6:14
|
|
|
|
|
LL | trait Trait: Sized {}
|
|
| ----- ^^^^^ ...because it requires `Self: Sized`
|
|
| |
|
|
| this trait cannot be made into an object...
|
|
= help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Trait` for this new enum and using it instead:
|
|
S
|
|
R
|
|
= note: required for the cast from `&S` to `&dyn Trait`
|
|
|
|
error[E0038]: the trait `Trait` cannot be made into an object
|
|
--> $DIR/wf-unsafe-trait-obj-match.rs:25:25
|
|
|
|
|
LL | let t: &dyn Trait = match opt() {
|
|
| _________________________^
|
|
LL | | Some(()) => &S,
|
|
LL | | None => &R,
|
|
LL | | };
|
|
| |_____^ `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/wf-unsafe-trait-obj-match.rs:6:14
|
|
|
|
|
LL | trait Trait: Sized {}
|
|
| ----- ^^^^^ ...because it requires `Self: Sized`
|
|
| |
|
|
| this trait cannot be made into an object...
|
|
= help: the following types implement the trait, consider defining an enum where each variant holds one of these types, implementing `Trait` for this new enum and using it instead:
|
|
S
|
|
R
|
|
= note: required for the cast from `&R` to `&dyn Trait`
|
|
|
|
error: aborting due to 3 previous errors
|
|
|
|
Some errors have detailed explanations: E0038, E0308.
|
|
For more information about an error, try `rustc --explain E0038`.
|