Detect missing `=>` after match guard during parsing
```
error: expected one of `,`, `:`, or `}`, found `.`
--> $DIR/missing-fat-arrow.rs:25:14
|
LL | Some(a) if a.value == b {
| - while parsing this struct
LL | a.value = 1;
| -^ expected one of `,`, `:`, or `}`
| |
| while parsing this struct field
|
help: try naming a field
|
LL | a: a.value = 1;
| ++
help: you might have meant to start a match arm after the match guard
|
LL | Some(a) if a.value == b => {
| ++
```
Fix#78585.
```
error: expected one of `,`, `:`, or `}`, found `.`
--> $DIR/missing-fat-arrow.rs:25:14
|
LL | Some(a) if a.value == b {
| - while parsing this struct
LL | a.value = 1;
| -^ expected one of `,`, `:`, or `}`
| |
| while parsing this struct field
|
help: try naming a field
|
LL | a: a.value = 1;
| ++
help: you might have meant to start a match arm after the match guard
|
LL | Some(a) if a.value == b => {
| ++
```
Fix#78585.
Improve invalid let expression handling
- Move all of the checks for valid let expression positions to parsing.
- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a valid location.
- Suppress some later errors and MIR construction for invalid let expressions.
- Fix a (drop) scope issue that was also responsible for #104172.
Fixes#104172Fixes#104868
- Add doc comment to new type
- Restore "only supported directly in conditions of `if` and `while` expressions" note
- Rename variant with clearer name
Previously some invalid let expressions would result in both a feature
error and a parsing error. Avoid this and ensure that we only emit the
parsing error when this happens.
There was an incomplete version of the check in parsing and a second
version in AST validation. This meant that some, but not all, invalid
uses were allowed inside macros/disabled cfgs. It also means that later
passes have a hard time knowing when the let expression is in a valid
location, sometimes causing ICEs.
- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a
valid location.
- Suppress later errors and MIR construction for invalid let
expressions.
Add explanatory note to 'expected item' error
Fixes#113110
It changes the diagnostic from this:
```
error: expected item, found `5`
--> ../test.rs:1:1
|
1 | 5
| ^ expected item
```
to this:
```
error: expected item, found `5`
--> ../test.rs:1:1
|
1 | 5
| ^ expected item
|
= note: items are things that can appear at the root of a module
= note: for a full list see https://doc.rust-lang.org/reference/items.html
```
It uses `once` chained with `(0..self.num_calls).map(...)` followed by
`.take(self.num_calls`. I found this hard to read. It's simpler to just
use `repeat_with`.
Make if let guard parsing consistent with normal guards
- Add tests that struct expressions are not allowed in `if let` and `while let` (no change, consistent with `if` and `while`)
- Allow struct expressions in `if let` guards (consistent with `if` guards).
r? `@cjgillot`
Closes#93817
cc #51114
suggest removing `impl` in generic trait bound position
rustc already does this recovery in type param position (`<T: impl Trait>` -> `<T: Trait>`).
This PR also adds that suggestion in trait bound position (e.g. `where T: impl Trait` or `trait Trait { type Assoc: impl Trait; }`)
parser: not insert dummy field in struct
Fixes#114636
This PR eliminates the dummy field, initially introduced in #113999, thereby enabling unrestricted use of `ident.unwrap()`. A side effect of this action is that we can only report the error of the first macro invocation field within the struct node.
An alternative solution might be giving a virtual name to the macro, but it appears more complex.(https://github.com/rust-lang/rust/issues/114636#issuecomment-1670228715). Furthermore, if you think https://github.com/rust-lang/rust/issues/114636#issuecomment-1670228715 is a better solution, feel free to close this PR.
Parse unnamed fields and anonymous structs or unions (no-recovery)
It is part of #114782 which implements #49804. Only parse anonymous structs or unions in struct field definition positions.
r? `@petrochenkov`
Anonymous structs or unions are only allowed in struct field
definitions.
Co-authored-by: carbotaniuman <41451839+carbotaniuman@users.noreply.github.com>
`Nonterminal`-related cleanups
In #114647 I am trying to remove `Nonterminal`. It has a number of preliminary cleanups that are worth merging even if #114647 doesn't merge, so let's do them in this PR.
r? `@petrochenkov`
It's much more complicated than it needs to be, and it doesn't modify
the expression. We can do the `Result` handling outside of it, and
change it to just return a span.
Also fix an errant comma that makes the comment hard to read.
Fix suggestion for attempting to define a string with single quotes
Currently attempting to compile `fn main() { let _ = '\\"'; }` will result in the following error message:
```
error: character literal may only contain one codepoint
--> src/main.rs:1:21
|
1 | fn main() { let _ = '\\"'; }
| ^^^^^
|
help: if you meant to write a `str` literal, use double quotes
|
1 | fn main() { let _ = "\\""; }
| ~~~~~
```
The suggestion is invalid as it fails to escape the `"`. This PR fixes the suggestion so that it now reads:
```
help: if you meant to write a `str` literal, use double quotes
|
1 | fn main() { let _ = "\\\""; }
| ~~~~~~
```
The relevant test is also updated to ensure that this does not regress in future.
Improve spans for indexing expressions
fixes#114388
Indexing is similar to method calls in having an arbitrary left-hand-side and then something on the right, which is the main part of the expression. Method calls already have a span for that right part, but indexing does not. This means that long method chains that use indexing have really bad spans, especially when the indexing panics and that span in coverted into a panic location.
This does the same thing as method calls for the AST and HIR, storing an extra span which is then put into the `fn_span` field in THIR.
r? compiler-errors
Indexing is similar to method calls in having an arbitrary
left-hand-side and then something on the right, which is the main part
of the expression. Method calls already have a span for that right part,
but indexing does not. This means that long method chains that use
indexing have really bad spans, especially when the indexing panics and
that span in coverted into a panic location.
This does the same thing as method calls for the AST and HIR, storing an
extra span which is then put into the `fn_span` field in THIR.
