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When encountering trait bound errors that satisfy some heuristics that tell us that the relevant trait for the user comes from the root obligation and not the current obligation, we use the root predicate for the main message. This allows to talk about "X doesn't implement Pattern<'_>" over the most specific case that just happened to fail, like "char doesn't implement Fn(&mut char)" in `tests/ui/traits/suggest-dereferences/root-obligation.rs` The heuristics are: - the type of the leaf predicate is (roughly) the same as the type from the root predicate, as a proxy for "we care about the root" - the leaf trait and the root trait are different, so as to avoid talking about `&mut T: Trait` and instead remain talking about `T: Trait` instead - the root trait is not `Unsize`, as to avoid talking about it in `tests/ui/coercion/coerce-issue-49593-box-never.rs`. ``` error[E0277]: the trait bound `&char: Pattern<'_>` is not satisfied --> $DIR/root-obligation.rs:6:38 | LL | .filter(|c| "aeiou".contains(c)) | -------- ^ the trait `Fn<(char,)>` is not implemented for `&char`, which is required by `&char: Pattern<'_>` | | | required by a bound introduced by this call | = note: required for `&char` to implement `FnOnce<(char,)>` = note: required for `&char` to implement `Pattern<'_>` note: required by a bound in `core::str::<impl str>::contains` --> $SRC_DIR/core/src/str/mod.rs:LL:COL help: consider dereferencing here | LL | .filter(|c| "aeiou".contains(*c)) | + ``` Fix #79359, fix #119983, fix #118779, cc #118415 (the suggestion needs to change).
55 lines
2.2 KiB
Plaintext
55 lines
2.2 KiB
Plaintext
error[E0277]: the trait bound `Box<{integer}>: Foo` is not satisfied
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--> $DIR/kindck-inherited-copy-bound.rs:21:16
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LL | take_param(&x);
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| ---------- ^^ the trait `Copy` is not implemented for `Box<{integer}>`, which is required by `Box<{integer}>: Foo`
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| required by a bound introduced by this call
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note: required for `Box<{integer}>` to implement `Foo`
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--> $DIR/kindck-inherited-copy-bound.rs:14:14
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LL | impl<T:Copy> Foo for T {
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| ---- ^^^ ^
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| |
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| unsatisfied trait bound introduced here
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note: required by a bound in `take_param`
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--> $DIR/kindck-inherited-copy-bound.rs:17:17
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LL | fn take_param<T:Foo>(foo: &T) { }
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| ^^^ required by this bound in `take_param`
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/kindck-inherited-copy-bound.rs:28:19
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LL | let z = &x as &dyn Foo;
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| ^^^^^^^^ `Foo` cannot be made into an object
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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>
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--> $DIR/kindck-inherited-copy-bound.rs:10:13
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LL | trait Foo : Copy {
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| --- ^^^^ ...because it requires `Self: Sized`
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| this trait cannot be made into an object...
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/kindck-inherited-copy-bound.rs:28:13
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LL | let z = &x as &dyn Foo;
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| ^^ `Foo` cannot be made into an object
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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>
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--> $DIR/kindck-inherited-copy-bound.rs:10:13
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LL | trait Foo : Copy {
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| --- ^^^^ ...because it requires `Self: Sized`
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| this trait cannot be made into an object...
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= note: required for the cast from `&Box<{integer}>` to `&dyn Foo`
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error: aborting due to 3 previous errors
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Some errors have detailed explanations: E0038, E0277.
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For more information about an error, try `rustc --explain E0038`.
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