Be more specific when type parameter shadows primitive type #36338
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @nikomatsakis (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see the contribution instructions for more information. |
| self.note(&format!("expected {} `{}`", label, expected)); | ||
| self.note(&format!(" found {} `{}`", label, found)); | ||
| self.note(&format!("expected {} `{}` {}", label, expected, expected_extra)); | ||
| self.note(&format!(" found {} `{}` {}", label, found, found_extra)); |
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I think it would be preferable to move the added spaces to the _extra variables, so that there isn't any trailing space in case the _extra variables are empty.
That should also fix the current three ui test failures.
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I've done so and rebased. All tests now pass.
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| @@ -550,7 +550,16 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { | |||
| }; | |||
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| if !is_simple_error { | |||
| diag.note_expected_found(&"type", &expected, &found); | |||
| if expected == found { | |||
| if let &TypeError::Sorts(ref values) = terr { | |||
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nit: This should be indented four spaces.
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Also, do we want to not error when terr is not &TypeError::Sorts(..) here?
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LGTM modulo comment |
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Yes, as @jseyfried noted, it seems like we are now missing a case where the "expected found" will not be printed, but otherwise looks good to me. |
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It'll be nice to see this fixed! |
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@nikomatsakis, @jseyfried incorporated your comments and rebased. |
When a type parameter shadows a primitive type, the error message
was non obvious. For example, given the file `file.rs`:
```rust
trait Parser<T> {
fn parse(text: &str) -> Option<T>;
}
impl<bool> Parser<bool> for bool {
fn parse(text: &str) -> Option<bool> {
Some(true)
}
}
fn main() {
println!("{}", bool::parse("ok").unwrap_or(false));
}
```
The output was:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool
|
= note: expected type `bool`
= note: found type `bool`
error: aborting due to previous error
```
We now show extra information about the type:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool
|
= note: expected type `bool` (type parameter)
= note: found type `bool` (bool)
error: aborting due to previous error
```
Fixes rust-lang#35030
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@nikomatsakis I believe this might be ready for merging. Would you agree? |
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@bors r+ |
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📌 Commit 68e8624 has been approved by |
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@estebank Thanks for the PR! |
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@jseyfried my pleasure! |
Be more specific when type parameter shadows primitive type
When a type parameter shadows a primitive type, the error message
was non obvious. For example, given the file `file.rs`:
```rust
trait Parser<T> {
fn parse(text: &str) -> Option<T>;
}
impl<bool> Parser<bool> for bool {
fn parse(text: &str) -> Option<bool> {
Some(true)
}
}
fn main() {
println!("{}", bool::parse("ok").unwrap_or(false));
}
```
The output was:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool a
|
= note: expected type `bool`
= note: found type `bool`
error: aborting due to previous error
```
We now show extra information about the type:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool a
|
= note: expected type `bool` (type parameter)
= note: found type `bool` (bool)
error: aborting due to previous error
```
Fixes #35030
When a type parameter shadows a primitive type, the error message
was non obvious. For example, given the file
file.rs:The output was:
We now show extra information about the type:
Fixes #35030