parse: recover on `const fn()` / `async fn()`
Recover on `const fn()` and `async fn()` function pointers, suggesting to remove the qualifier.
For example:
```
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
```
r? @estebank
Improve error messages for raw strings (#60762)
This diff improves error messages around raw strings in a few ways:
- Catch extra trailing `#` in the parser. This can't be handled in the lexer because we could be in a macro that actually expects another # (see test)
- Refactor & unify error handling in the lexer between ByteStrings and RawByteStrings
- Detect potentially intended terminators (longest sequence of "#*" is suggested)
Fixes#60762
cc @estebank who reviewed the original (abandoned) PR for the same ticket.
r? @Centril
This diff improves error messages around raw strings in a few ways:
- Catch extra trailing `#` in the parser. This can't be handled in the lexer because we could be in a macro that actually expects another # (see test)
- Refactor & unify error handling in the lexer between ByteStrings and RawByteStrings
- Detect potentially intended terminators (longest sequence of "#*" is suggested)
`error_bad_item_kind`: add help text
For example, this adds:
```
= help: consider moving the `use` import out to a nearby module scope
```
r? @petrochenkov @estebank
Fixes https://github.com/rust-lang/rust/issues/37205.
Tweak chained operators diagnostic
Use more selective spans
Improve suggestion output
Be more selective when displaying suggestions
Silence some knock-down type errors
r? @Centril
couple more clippy fixes (let_and_return, if_same_then_else)
* summarize if-else-code with identical blocks (clippy::if_same_then_else)
* don't create variable bindings just to return the bound value immediately (clippy::let_and_return)
parser: recover on `for<'a> |...| body` closures
When encountering `for` and `<` is 1 token ahead, interpret this as an explicitly quantified generic closure and recover, rather than attempting to parse a `for` loop. This provides both improved diagnostics as well as an insurance policy for the ability to use this as the syntax for generic closures in the future.
As requested by r? @eddyb
