diff options
9 files changed, 137 insertions, 0 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs index 01cd3c57925..21ea48c6c83 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs @@ -294,6 +294,75 @@ impl<T> Trait<T> for X { ); } } + (ty::Dynamic(t, _, ty::DynKind::Dyn), ty::Alias(ty::Opaque, alias)) + if let Some(def_id) = t.principal_def_id() + && tcx.explicit_item_bounds(alias.def_id).skip_binder().iter().any( + |(pred, _span)| match pred.kind().skip_binder() { + ty::ClauseKind::Trait(trait_predicate) + if trait_predicate.polarity + == ty::ImplPolarity::Positive => + { + trait_predicate.def_id() == def_id + } + _ => false, + }, + ) => + { + diag.help(format!( + "you can box the `{}` to coerce it to `Box<{}>`, but you'll have to \ + change the expected type as well", + values.found, values.expected, + )); + } + (ty::Dynamic(t, _, ty::DynKind::Dyn), _) + if let Some(def_id) = t.principal_def_id() => + { + let mut impl_def_ids = vec![]; + tcx.for_each_relevant_impl(def_id, values.found, |did| { + impl_def_ids.push(did) + }); + if let [_] = &impl_def_ids[..] { + let trait_name = tcx.item_name(def_id); + diag.help(format!( + "`{}` implements `{trait_name}` so you could box the found value \ + and coerce it to the trait object `Box<dyn {trait_name}>`, you \ + will have to change the expected type as well", + values.found, + )); + } + } + (_, ty::Dynamic(t, _, ty::DynKind::Dyn)) + if let Some(def_id) = t.principal_def_id() => + { + let mut impl_def_ids = vec![]; + tcx.for_each_relevant_impl(def_id, values.expected, |did| { + impl_def_ids.push(did) + }); + if let [_] = &impl_def_ids[..] { + let trait_name = tcx.item_name(def_id); + diag.help(format!( + "`{}` implements `{trait_name}` so you could change the expected \ + type to `Box<dyn {trait_name}>`", + values.expected, + )); + } + } + (ty::Dynamic(t, _, ty::DynKind::DynStar), _) + if let Some(def_id) = t.principal_def_id() => + { + let mut impl_def_ids = vec![]; + tcx.for_each_relevant_impl(def_id, values.found, |did| { + impl_def_ids.push(did) + }); + if let [_] = &impl_def_ids[..] { + let trait_name = tcx.item_name(def_id); + diag.help(format!( + "`{}` implements `{trait_name}`, `#[feature(dyn_star)]` is likely \ + not enabled; that feature it is currently incomplete", + values.found, + )); + } + } (_, ty::Alias(ty::Opaque, opaque_ty)) | (ty::Alias(ty::Opaque, opaque_ty), _) => { if opaque_ty.def_id.is_local() diff --git a/tests/ui/dst/dst-bad-assign-3.stderr b/tests/ui/dst/dst-bad-assign-3.stderr index 6dd3434fd21..007f6b898be 100644 --- a/tests/ui/dst/dst-bad-assign-3.stderr +++ b/tests/ui/dst/dst-bad-assign-3.stderr @@ -8,6 +8,7 @@ LL | f5.2 = Bar1 {f: 36}; | = note: expected trait object `dyn ToBar` found struct `Bar1` + = help: `Bar1` implements `ToBar` so you could box the found value and coerce it to the trait object `Box<dyn ToBar>`, you will have to change the expected type as well error[E0277]: the size for values of type `dyn ToBar` cannot be known at compilation time --> $DIR/dst-bad-assign-3.rs:33:5 diff --git a/tests/ui/dst/dst-bad-assign.stderr b/tests/ui/dst/dst-bad-assign.stderr index d8d1057876f..f935d27e96e 100644 --- a/tests/ui/dst/dst-bad-assign.stderr +++ b/tests/ui/dst/dst-bad-assign.stderr @@ -8,6 +8,7 @@ LL | f5.ptr = Bar1 {f: 36}; | = note: expected trait object `dyn ToBar` found struct `Bar1` + = help: `Bar1` implements `ToBar` so you could box the found value and coerce it to the trait object `Box<dyn ToBar>`, you will have to change the expected type as well error[E0277]: the size for values of type `dyn ToBar` cannot be known at compilation time --> $DIR/dst-bad-assign.rs:35:5 diff --git a/tests/ui/dyn-star/no-implicit-dyn-star.stderr b/tests/ui/dyn-star/no-implicit-dyn-star.stderr index 06c7bcc5748..bea334a8a69 100644 --- a/tests/ui/dyn-star/no-implicit-dyn-star.stderr +++ b/tests/ui/dyn-star/no-implicit-dyn-star.stderr @@ -8,6 +8,7 @@ LL | dyn_star_foreign::require_dyn_star_display(1usize); | = note: expected trait object `(dyn* std::fmt::Display + 'static)` found type `usize` + = help: `usize` implements `Display`, `#[feature(dyn_star)]` is likely not enabled; that feature it is currently incomplete note: function defined here --> $DIR/auxiliary/dyn-star-foreign.rs:6:8 | diff --git a/tests/ui/generic-associated-types/issue-79422.extended.stderr b/tests/ui/generic-associated-types/issue-79422.extended.stderr index 14492266cda..ae1526296a7 100644 --- a/tests/ui/generic-associated-types/issue-79422.extended.stderr +++ b/tests/ui/generic-associated-types/issue-79422.extended.stderr @@ -27,6 +27,7 @@ LL | type VRefCont<'a> = &'a V where Self: 'a; | ^^^^^ = note: expected trait object `(dyn RefCont<'_, u8> + 'static)` found reference `&u8` + = help: `&u8` implements `RefCont` so you could box the found value and coerce it to the trait object `Box<dyn RefCont>`, you will have to change the expected type as well = note: required for the cast from `Box<BTreeMap<u8, u8>>` to `Box<dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>>` error: aborting due to 2 previous errors diff --git a/tests/ui/impl-trait/dyn-impl-type-mismatch.rs b/tests/ui/impl-trait/dyn-impl-type-mismatch.rs new file mode 100644 index 00000000000..c6170abb582 --- /dev/null +++ b/tests/ui/impl-trait/dyn-impl-type-mismatch.rs @@ -0,0 +1,18 @@ +trait Trait {} +struct Struct; +impl Trait for Struct {} +fn foo() -> impl Trait { + Struct +} +fn main() { + let a: Box<dyn Trait> = if true { + Box::new(Struct) + } else { + foo() //~ ERROR E0308 + }; + let a: dyn Trait = if true { + Struct //~ ERROR E0308 + } else { + foo() //~ ERROR E0308 + }; +} diff --git a/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr b/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr new file mode 100644 index 00000000000..ddbdaf3eb4b --- /dev/null +++ b/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr @@ -0,0 +1,43 @@ +error[E0308]: mismatched types + --> $DIR/dyn-impl-type-mismatch.rs:11:9 + | +LL | fn foo() -> impl Trait { + | ---------- the found opaque type +... +LL | foo() + | ^^^^^ expected `Box<dyn Trait>`, found opaque type + | + = note: expected struct `Box<dyn Trait>` + found opaque type `impl Trait` + = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html +help: store this in the heap by calling `Box::new` + | +LL | Box::new(foo()) + | +++++++++ + + +error[E0308]: mismatched types + --> $DIR/dyn-impl-type-mismatch.rs:14:9 + | +LL | Struct + | ^^^^^^ expected `dyn Trait`, found `Struct` + | + = note: expected trait object `dyn Trait` + found struct `Struct` + = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well + +error[E0308]: mismatched types + --> $DIR/dyn-impl-type-mismatch.rs:16:9 + | +LL | fn foo() -> impl Trait { + | ---------- the found opaque type +... +LL | foo() + | ^^^^^ expected `dyn Trait`, found opaque type + | + = note: expected trait object `dyn Trait` + found opaque type `impl Trait` + = help: you can box the `impl Trait` to coerce it to `Box<dyn Trait>`, but you'll have to change the expected type as well + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0308`. diff --git a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr index 4a52f82540d..9cc199d1e0e 100644 --- a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr +++ b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr @@ -6,6 +6,7 @@ LL | fn fuz() -> (usize, Trait) { (42, Struct) } | = note: expected trait object `(dyn Trait + 'static)` found struct `Struct` + = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time --> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:13 @@ -27,6 +28,7 @@ LL | fn bar() -> (usize, dyn Trait) { (42, Struct) } | = note: expected trait object `(dyn Trait + 'static)` found struct `Struct` + = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time --> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:13 diff --git a/tests/ui/methods/issues/issue-61525.stderr b/tests/ui/methods/issues/issue-61525.stderr index a329b52e373..2670a3e4755 100644 --- a/tests/ui/methods/issues/issue-61525.stderr +++ b/tests/ui/methods/issues/issue-61525.stderr @@ -27,6 +27,7 @@ LL | 1.query::<dyn ToString>("") | = note: expected trait object `dyn ToString` found reference `&'static str` + = help: `&'static str` implements `ToString` so you could box the found value and coerce it to the trait object `Box<dyn ToString>`, you will have to change the expected type as well note: method defined here --> $DIR/issue-61525.rs:2:8 | |