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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).
138 lines
5.2 KiB
Plaintext
138 lines
5.2 KiB
Plaintext
error[E0412]: cannot find type `N` in this scope
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--> $DIR/issue-50480.rs:3:12
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^ not found in this scope
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help: you might be missing a type parameter
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LL | struct Foo<N>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| +++
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error[E0412]: cannot find type `NotDefined` in this scope
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--> $DIR/issue-50480.rs:3:15
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^ not found in this scope
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error[E0412]: cannot find type `N` in this scope
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--> $DIR/issue-50480.rs:3:12
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^ not found in this scope
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help: you might be missing a type parameter
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LL | struct Foo<N>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| +++
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error[E0412]: cannot find type `NotDefined` in this scope
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--> $DIR/issue-50480.rs:3:15
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^ not found in this scope
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help: you might be missing a type parameter
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LL | struct Foo<NotDefined>(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ++++++++++++
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error[E0412]: cannot find type `N` in this scope
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--> $DIR/issue-50480.rs:14:18
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LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| - ^
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| |
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| similarly named type parameter `T` defined here
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help: a type parameter with a similar name exists
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LL | struct Bar<T>(T, T, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ~
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help: you might be missing a type parameter
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LL | struct Bar<T, N>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| +++
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error[E0412]: cannot find type `NotDefined` in this scope
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--> $DIR/issue-50480.rs:14:21
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LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^ not found in this scope
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error[E0204]: the trait `Copy` cannot be implemented for this type
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--> $DIR/issue-50480.rs:1:17
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LL | #[derive(Clone, Copy)]
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| ^^^^
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LL |
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| -------- ------ this field does not implement `Copy`
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| |
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| this field does not implement `Copy`
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= note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
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error[E0204]: the trait `Copy` cannot be implemented for this type
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--> $DIR/issue-50480.rs:11:17
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LL | #[derive(Clone, Copy)]
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| ^^^^
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...
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LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| -------- ------ this field does not implement `Copy`
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| |
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| this field does not implement `Copy`
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= note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
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error[E0277]: `i32` is not an iterator
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--> $DIR/issue-50480.rs:3:27
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
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= help: the trait `Iterator` is not implemented for `i32`
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error[E0277]: `i32` is not an iterator
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--> $DIR/issue-50480.rs:14:33
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LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
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= help: the trait `Iterator` is not implemented for `i32`
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error[E0277]: `i32` is not an iterator
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--> $DIR/issue-50480.rs:3:28
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LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^ `i32` is not an iterator
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= help: the trait `Iterator` is not implemented for `i32`
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error[E0277]: `i32` is not an iterator
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--> $DIR/issue-50480.rs:11:10
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LL | #[derive(Clone, Copy)]
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| ^^^^^ `i32` is not an iterator
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= help: the trait `Iterator` is not implemented for `i32`
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= note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
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error[E0277]: `i32` is not an iterator
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--> $DIR/issue-50480.rs:14:33
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LL | #[derive(Clone, Copy)]
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| ----- in this derive macro expansion
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...
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LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
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| ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
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= help: the trait `Iterator` is not implemented for `i32`
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= note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
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error: aborting due to 13 previous errors
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Some errors have detailed explanations: E0204, E0277, E0412.
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For more information about an error, try `rustc --explain E0204`.
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