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maybe_lint_impl_trait: separate is_downgradable from is_object_safe

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This commit is contained in:
trevyn 2024-01-20 20:12:54 +04:00
parent 6745c6000a
commit b58a8a98cd
3 changed files with 65 additions and 53 deletions
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16
compiler/rustc_hir_analysis/src/astconv/lint.rs
View file

@ -94,15 +94,17 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
return false;
};
let impl_sugg = vec![(self_ty.span.shrink_to_lo(), "impl ".to_string())];
let mut is_downgradable = true;
let is_object_safe = match self_ty.kind {
hir::TyKind::TraitObject(objects, ..) => {
objects.iter().all(|o| match o.trait_ref.path.res {
Res::Def(DefKind::Trait, id) if Some(id) == owner => {
// When we're dealing with a recursive trait, we don't want to downgrade
// the error, so we consider them to be object safe always. (#119652)
true
Res::Def(DefKind::Trait, id) => {
if Some(id) == owner {
// For recursive traits, don't downgrade the error. (#119652)
is_downgradable = false;
}
tcx.check_is_object_safe(id)
}
Res::Def(DefKind::Trait, id) => tcx.check_is_object_safe(id),
_ => false,
})
}
@ -130,7 +132,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
],
Applicability::MachineApplicable,
);
} else if diag.is_error() {
} else if diag.is_error() && is_downgradable {
// We'll emit the object safety error already, with a structured suggestion.
diag.downgrade_to_delayed_bug();
}
@ -156,7 +158,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
if !is_object_safe {
diag.note(format!("`{trait_name}` it is not object safe, so it can't be `dyn`"));
if diag.is_error() {
if diag.is_error() && is_downgradable {
// We'll emit the object safety error already, with a structured suggestion.
diag.downgrade_to_delayed_bug();
}

6
tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.rs
View file

@ -8,16 +8,18 @@ trait A: Sized {
//~| ERROR the trait `A` cannot be made into an object
}
trait B {
fn f(a: B) -> B;
fn f(b: B) -> B;
//~^ ERROR trait objects must include the `dyn` keyword
//~| ERROR trait objects must include the `dyn` keyword
//~| ERROR associated item referring to unboxed trait object for its own trait
//~| ERROR the trait `B` cannot be made into an object
}
trait C {
fn f(&self, a: C) -> C;
fn f(&self, c: C) -> C;
//~^ ERROR trait objects must include the `dyn` keyword
//~| ERROR trait objects must include the `dyn` keyword
//~| ERROR associated item referring to unboxed trait object for its own trait
//~| ERROR the trait `C` cannot be made into an object
}
fn main() {}

96
tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.stderr
View file

@ -30,18 +30,18 @@ error: associated item referring to unboxed trait object for its own trait
|
LL | trait B {
| - in this trait
LL | fn f(a: B) -> B;
LL | fn f(b: B) -> B;
| ^ ^
|
help: you might have meant to use `Self` to refer to the implementing type
|
LL | fn f(a: Self) -> Self;
LL | fn f(b: Self) -> Self;
| ~~~~ ~~~~
error[E0038]: the trait `B` cannot be made into an object
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13
|
LL | fn f(a: B) -> B;
LL | fn f(b: B) -> B;
| ^ `B` 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>
@ -49,23 +49,53 @@ note: for a trait to be "object safe" it needs to allow building a vtable to all
|
LL | trait B {
| - this trait cannot be made into an object...
LL | fn f(a: B) -> B;
LL | fn f(b: B) -> B;
| ^ ...because associated function `f` has no `self` parameter
help: consider turning `f` into a method by giving it a `&self` argument
|
LL | fn f(&self, a: B) -> B;
LL | fn f(&self, b: B) -> B;
| ++++++
help: alternatively, consider constraining `f` so it does not apply to trait objects
|
LL | fn f(a: B) -> B where Self: Sized;
LL | fn f(b: B) -> B where Self: Sized;
| +++++++++++++++++
error: associated item referring to unboxed trait object for its own trait
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20
|
LL | trait C {
| - in this trait
LL | fn f(&self, c: C) -> C;
| ^ ^
|
help: you might have meant to use `Self` to refer to the implementing type
|
LL | fn f(&self, c: Self) -> Self;
| ~~~~ ~~~~
error[E0038]: the trait `C` cannot be made into an object
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20
|
LL | fn f(&self, c: C) -> C;
| ----- ^ `C` cannot be made into an object
| |
| help: consider changing method `f`'s `self` parameter to be `&self` (notice the capitalization): `&Self`
|
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/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:10
|
LL | trait C {
| - this trait cannot be made into an object...
LL | fn f(&self, c: C) -> C;
| ^^^^^ ...because method `f`'s `self` parameter cannot be dispatched on
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:13
|
LL | fn f(a: A) -> A;
| ^
|
= note: `A` it is not object safe, so it can't be `dyn`
help: use a new generic type parameter, constrained by `A`
|
LL | fn f<T: A>(a: T) -> A;
@ -74,10 +104,6 @@ help: you can also use an opaque type, but users won't be able to specify the ty
|
LL | fn f(a: impl A) -> A;
| ++++
help: alternatively, use a trait object to accept any type that implements `A`, accessing its methods at runtime using dynamic dispatch
|
LL | fn f(a: &dyn A) -> A;
| ++++
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:4:19
@ -85,84 +111,66 @@ error[E0782]: trait objects must include the `dyn` keyword
LL | fn f(a: A) -> A;
| ^
|
help: use `impl A` to return an opaque type, as long as you return a single underlying type
help: `A` is not object safe, use `impl A` to return an opaque type, as long as you return a single underlying type
|
LL | fn f(a: A) -> impl A;
| ++++
help: alternatively, you can return an owned trait object
|
LL | fn f(a: A) -> Box<dyn A>;
| +++++++ +
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:13
|
LL | fn f(a: B) -> B;
LL | fn f(b: B) -> B;
| ^
|
= note: `B` it is not object safe, so it can't be `dyn`
help: use a new generic type parameter, constrained by `B`
|
LL | fn f<T: B>(a: T) -> B;
LL | fn f<T: B>(b: T) -> B;
| ++++++ ~
help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
|
LL | fn f(a: impl B) -> B;
| ++++
help: alternatively, use a trait object to accept any type that implements `B`, accessing its methods at runtime using dynamic dispatch
|
LL | fn f(a: &dyn B) -> B;
LL | fn f(b: impl B) -> B;
| ++++
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:11:19
|
LL | fn f(a: B) -> B;
LL | fn f(b: B) -> B;
| ^
|
help: use `impl B` to return an opaque type, as long as you return a single underlying type
help: `B` is not object safe, use `impl B` to return an opaque type, as long as you return a single underlying type
|
LL | fn f(a: B) -> impl B;
LL | fn f(b: B) -> impl B;
| ++++
help: alternatively, you can return an owned trait object
|
LL | fn f(a: B) -> Box<dyn B>;
| +++++++ +
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:20
|
LL | fn f(&self, a: C) -> C;
LL | fn f(&self, c: C) -> C;
| ^
|
= note: `C` it is not object safe, so it can't be `dyn`
help: use a new generic type parameter, constrained by `C`
|
LL | fn f<T: C>(&self, a: T) -> C;
LL | fn f<T: C>(&self, c: T) -> C;
| ++++++ ~
help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
|
LL | fn f(&self, a: impl C) -> C;
| ++++
help: alternatively, use a trait object to accept any type that implements `C`, accessing its methods at runtime using dynamic dispatch
|
LL | fn f(&self, a: &dyn C) -> C;
LL | fn f(&self, c: impl C) -> C;
| ++++
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/object-unsafe-trait-should-use-self-2021-without-dyn.rs:18:26
|
LL | fn f(&self, a: C) -> C;
LL | fn f(&self, c: C) -> C;
| ^
|
help: use `impl C` to return an opaque type, as long as you return a single underlying type
help: `C` is not object safe, use `impl C` to return an opaque type, as long as you return a single underlying type
|
LL | fn f(&self, a: C) -> impl C;
LL | fn f(&self, c: C) -> impl C;
| ++++
help: alternatively, you can return an owned trait object
|
LL | fn f(&self, a: C) -> Box<dyn C>;
| +++++++ +
error: aborting due to 10 previous errors
error: aborting due to 12 previous errors
Some errors have detailed explanations: E0038, E0782.
For more information about an error, try `rustc --explain E0038`.