From b58a8a98cdee84a9636c08877f623b97033c7dda Mon Sep 17 00:00:00 2001 From: trevyn <230691+trevyn@users.noreply.github.com> Date: Sat, 20 Jan 2024 20:12:54 +0400 Subject: [PATCH] `maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe` --- .../rustc_hir_analysis/src/astconv/lint.rs | 16 ++-- ...-trait-should-use-self-2021-without-dyn.rs | 6 +- ...it-should-use-self-2021-without-dyn.stderr | 96 ++++++++++--------- 3 files changed, 65 insertions(+), 53 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/astconv/lint.rs b/compiler/rustc_hir_analysis/src/astconv/lint.rs index b5f42e98127ee..27dc088d5dd8c 100644 --- a/compiler/rustc_hir_analysis/src/astconv/lint.rs +++ b/compiler/rustc_hir_analysis/src/astconv/lint.rs @@ -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(); } diff --git a/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.rs b/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.rs index f48c3d124ddac..dbdfde6dd5061 100644 --- a/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.rs +++ b/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.rs @@ -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() {} diff --git a/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.stderr b/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.stderr index 73d5a24f83137..60eb72ab4f768 100644 --- a/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.stderr +++ b/tests/ui/suggestions/object-unsafe-trait-should-use-self-2021-without-dyn.stderr @@ -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 @@ -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 + --> $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(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; - | +++++++ + 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(a: T) -> B; +LL | fn f(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; - | +++++++ + 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(&self, a: T) -> C; +LL | fn f(&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; - | +++++++ + -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`.