E0599 suggestions and elision of generic argument if no canditate is found #84221
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…d anywhere and sugetion of type with method when found.
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r? @estebank (rust-highfive has picked a reviewer for you, use r? to override) |
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I change it to show |
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May 21, 2021
| // number of type to shows at most. | ||
| const LIMIT: usize = 3; | ||
| let mut note = format!("The {item_kind} was found for"); | ||
| if inherent_impls_candidate.len() > 1 { |
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I think it might be better to make a list of items instead of enumerating them in text, because that is easier to scan when reading the error.
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This might work better as well in the case of really long type names with lots of type parameters (that we see in the wild).
| inherent_impls_candidate.len() - LIMIT | ||
| ); | ||
| } | ||
| err.note(&format!("{}.", note)); |
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We don't capitalize or have a final period on sentences. We only break that convention if we have long text with multiple sentences, but it is heavily frown upon.
| LL | wrapper.method(); | ||
| | ^^^^^^ method not found in `Wrapper2<'_, bool, 3_usize>` | ||
| | | ||
| = note: The method was found for Wrapper2<'a, i8, C>, Wrapper2<'a, i32, C> and Wrapper2<'a, i32, C>. |
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Looking at this I am concerned about some trait bounds I've seen that generate huge types, but I don't know how we'd present these in a better way 🤷♂️
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The case where trait bounds are not met are manage by another part of the code, therefore we should not see long trait bounds. I have added a test for this case.
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| if let Some((path_string, _)) = ty_str.split_once('<') { | ||
| ty_str_reported = path_string.to_string(); | ||
| } |
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Ideally we'd just take the name ident of the type and use that. I think item_name.to_string() would work here.
String operations are brittle and can break as things change in the codebase.
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item_name is the method we are looking to call. I did not find a way to print the type without the generic parameter otherwise. Do you know a way to do it ?
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What is the type of item_name from which you get span from?
I think that might have a string representation, and if not a field that is only the name with type Ident, which has a string representation of only the identifier.
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Yes it is an Ident, but this does not represent the type. This is the indent of the method
For instance it is used here:
https://github.com/ABouttefeux/rust/blob/120691c590c4309fda31994931b9a561b4249c33/compiler/rustc_typeck/src/check/method/suggest.rs#L422-L431
Co-authored-by: Esteban Kuber <[email protected]>
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| --> $DIR/method-not-found-generic-arg-elision.rs:82:23 | ||
| | | ||
| LL | struct Point<T> { | ||
| | --------------- method `distance` not found for this |
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Looking at this with fresh eyes in context, it might make sense to expand this label to be method distance not found for Point when T is i32, but it is found when T is f64, but maybe that's too verbose.
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I am not sure how to get the indent for T. Also it might become very long with multiple generic parameters.
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| = note: the method was found for Wrapper<i8> | ||
| = note: the method was found for Wrapper<i16> | ||
| = note: the method was found for Wrapper<i32> | ||
| = note: the method was found for 3 more types |
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Ideally this would be a single note:
= note: the method `method` was found for
- `Wrapper<i8>`
- `Wrapper<i16>`
- `Wrapper<i32>`
- `Wrapper<u8>`
and 2 more types
| @@ -3,6 +3,8 @@ error[E0599]: no function or associated item named `new_undirected` found for st | |||
| | | |||
| LL | let ug = Graph::<i32, i32>::new_undirected(); | |||
| | ^^^^^^^^^^^^^^ function or associated item not found in `issue_30123_aux::Graph<i32, i32>` | |||
| | | |||
| = note: the function or associated item was found for issue_30123_aux::Graph<N, E, Undirected> | |||
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This would ideally talk about Graph<i32, i32, Undirected>, potentially mentioning the Ty default of Directed. No need to tackle this now.
| .map(|impl_item| self.tcx.at(span).type_of(*impl_item)) | ||
| .collect::<Vec<_>>(); | ||
| // number of type to shows at most. | ||
| let limit = if type_candidates.len() == 4 { 4 } else { 3 }; |
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Suggested change
| let limit = if type_candidates.len() == 4 { 4 } else { 3 }; | |
| let limit = if type_candidates.len() == 5 { 5 } else { 4 }; |
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| for ty in type_candidates.iter().take(limit) { | ||
| err.note(&format!("the {item_kind} was found for {}", ty)); | ||
| } | ||
| if type_candidates.len() > limit { | ||
| err.note(&format!( | ||
| "the {item_kind} was found for {} more types", | ||
| type_candidates.len() - limit | ||
| )); | ||
| } |
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Instead of emitting a note on each iteration, construct a single string to be emitted.
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…estebank E0599 suggestions and elision of generic argument if no canditate is found fixes rust-lang#81576 changes: In error E0599 (method not found) generic argument are eluded if the method was not found anywhere. If the method was found in another inherent implementation suggest that it was found elsewhere. Example ```rust struct Wrapper<T>(T); struct Wrapper2<T> { x: T, } impl Wrapper2<i8> { fn method(&self) {} } fn main() { let wrapper = Wrapper(i32); wrapper.method(); let wrapper2 = Wrapper2{x: i32}; wrapper2.method(); } ``` ``` Error[E0599]: no method named `method` found for struct `Wrapper<_>` in the current scope .... error[E0599]: no method named `method` found for struct `Wrapper2<i32>` in the current scope ... = note: The method was found for Wrapper2<i8>. ``` I am not very happy with the ```no method named `test` found for struct `Vec<_, _>` in the current scope```. I think it might be better to show only one generic argument `Vec<_>` if there is a default one. But I haven't yet found a way to do that,
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…estebank E0599 suggestions and elision of generic argument if no canditate is found fixes rust-lang#81576 changes: In error E0599 (method not found) generic argument are eluded if the method was not found anywhere. If the method was found in another inherent implementation suggest that it was found elsewhere. Example ```rust struct Wrapper<T>(T); struct Wrapper2<T> { x: T, } impl Wrapper2<i8> { fn method(&self) {} } fn main() { let wrapper = Wrapper(i32); wrapper.method(); let wrapper2 = Wrapper2{x: i32}; wrapper2.method(); } ``` ``` Error[E0599]: no method named `method` found for struct `Wrapper<_>` in the current scope .... error[E0599]: no method named `method` found for struct `Wrapper2<i32>` in the current scope ... = note: The method was found for Wrapper2<i8>. ``` I am not very happy with the ```no method named `test` found for struct `Vec<_, _>` in the current scope```. I think it might be better to show only one generic argument `Vec<_>` if there is a default one. But I haven't yet found a way to do that,
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Rollup of 8 pull requests Successful merges: - rust-lang#84221 (E0599 suggestions and elision of generic argument if no canditate is found) - rust-lang#84701 (stabilize member constraints) - rust-lang#85564 ( readd capture disjoint fields gate) - rust-lang#85583 (Get rid of PreviousDepGraph.) - rust-lang#85649 (Update cc) - rust-lang#85689 (Remove Iterator #[rustc_on_unimplemented]s that no longer apply.) - rust-lang#85719 (Add inline attr to CString::into_inner so it can optimize out NonNull checks) - rust-lang#85725 (Remove unneeded workaround) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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fixes #81576
changes: In error E0599 (method not found) generic argument are eluded if the method was not found anywhere. If the method was found in another inherent implementation suggest that it was found elsewhere.
Example
I am not very happy with the
no method named `test` found for struct `Vec<_, _>` in the current scope. I think it might be better to show only one generic argumentVec<_>if there is a default one. But I haven't yet found a way to do that,