parse: recover on const fn() / async fn()
#70421
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cc also @petrochenkov |
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| error: an `fn` pointer type cannot be `async` | ||
| --> $DIR/recover-const-async-fn-ptr.rs:6:11 | ||
| | | ||
| LL | type T3 = async fn(); | ||
| | -----^^^^^ | ||
| | | | ||
| | `async` because of this | ||
| | help: remove the `async` qualifier |
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Do you feel it would make sense to add some explanation of what async does to functions in the first place? Something along the lines of
error: an `fn` pointer type cannot be `async`
--> $DIR/recover-const-async-fn-ptr.rs:6:11
|
LL | type T3 = async fn();
| -----^^^^^
| |
| `async` because of this
| help: remove the `async` qualifier
= note: `async` functions only modify the return type of the function to be wrapped in a `std::future::Future<Output = ReturnType>`, an `async fn()` would be the same as `fn() -> Future<Output = ()>`
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That would have to be fn() -> Box<dyn Future<Output = ()>> or some such as fn() -> impl A is not valid. I think I'd prefer to keep things simple now, as I did this PR mostly as a refactoring (improving diagnostics is secondary).
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| /// Emit an error for the given bad function pointer qualifier. | ||
| fn error_fn_ptr_bad_qualifier(&self, span: Span, qual_span: Span, qual: &str) { | ||
| self.struct_span_err(span, &format!("an `fn` pointer type cannot be `{}`", qual)) | ||
| .span_label(qual_span, format!("`{}` because of this", qual)) | ||
| .span_suggestion_short( | ||
| qual_span, | ||
| &format!("remove the `{}` qualifier", qual), | ||
| String::new(), | ||
| Applicability::MaybeIncorrect, | ||
| ) | ||
| .emit(); | ||
| } |
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Could we move this to parser/diagnostics.rs?
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I generally prefer to keep parsing of various things more self-contained, and diagnostics.rs is larger than ty.rs in any case. :)
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@bors r=estebank |
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Rollup of 8 pull requests Successful merges: - rust-lang#70281 (Implement Hash for Infallible) - rust-lang#70421 (parse: recover on `const fn()` / `async fn()`) - rust-lang#70615 (Renamed `PerDefTables` to `Tables`) - rust-lang#70631 (Update cargo) - rust-lang#70634 (Remove some reexports in `rustc_middle`) - rust-lang#70658 (add `STILL_FURTHER_SPECIALIZABLE` flag) - rust-lang#70678 (Add missing markdown rust annotation) - rust-lang#70681 (Handle unterminated raw strings with no #s properly) Failed merges: r? @ghost
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Recover on
const fn()andasync fn()function pointers, suggesting to remove the qualifier.For example:
r? @estebank