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Handle case of incomplete local ty more gracefully

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When encountering a local binding with a type that isn't completed, the
parser will reach a `=` token. When this happen, consider the type
"complete" as far as the parser is concerned to avoid further errors
being emitted by parse recovery logic.
This commit is contained in:
Esteban Küber 2020-07-14 10:35:59 -07:00
parent 23744c84d9
commit ce3bd29c68
3 changed files with 20 additions and 55 deletions
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14
src/librustc_parse/parser/stmt.rs
View file

@ -162,13 +162,19 @@ impl<'a> Parser<'a> {
match self.parse_ty() {
Ok(ty) => (None, Some(ty)),
Err(mut err) => {
// Rewind to before attempting to parse the type and continue parsing.
let parser_snapshot_after_type =
mem::replace(self, parser_snapshot_before_type);
if let Ok(snip) = self.span_to_snippet(pat.span) {
err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
}
(Some((parser_snapshot_after_type, colon_sp, err)), None)
let err = if self.check(&token::Eq) {
err.emit();
None
} else {
// Rewind to before attempting to parse the type and continue parsing.
let parser_snapshot_after_type =
mem::replace(self, parser_snapshot_before_type);
Some((parser_snapshot_after_type, colon_sp, err))
};
(err, None)
}
}
} else {

7
src/test/ui/issues/issue-34334.rs
View file

@ -1,11 +1,6 @@
fn main () {
let sr: Vec<(u32, _, _) = vec![];
//~^ ERROR expected one of `,` or `>`, found `=`
//~| ERROR expected value, found struct `Vec`
//~| ERROR mismatched types
//~| ERROR invalid left-hand side of assignment
//~| ERROR expected expression, found reserved identifier `_`
//~| ERROR expected expression, found reserved identifier `_`
let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
//~^ ERROR no method named `iter` found
//~^ ERROR a value of type `std::vec::Vec<(u32, _, _)>` cannot be built
}

54
src/test/ui/issues/issue-34334.stderr
View file

@ -1,55 +1,19 @@
error: expected expression, found reserved identifier `_`
--> $DIR/issue-34334.rs:2:23
|
LL | let sr: Vec<(u32, _, _) = vec![];
| ^ expected expression
error: expected expression, found reserved identifier `_`
--> $DIR/issue-34334.rs:2:26
|
LL | let sr: Vec<(u32, _, _) = vec![];
| ^ expected expression
error: expected one of `,` or `>`, found `=`
--> $DIR/issue-34334.rs:2:29
|
LL | let sr: Vec<(u32, _, _) = vec![];
| --- ^ expected one of `,` or `>`
| | |
| | help: use `=` if you meant to assign
| -- ^ expected one of `,` or `>`
| |
| while parsing the type for `sr`
error[E0423]: expected value, found struct `Vec`
--> $DIR/issue-34334.rs:2:13
|
LL | let sr: Vec<(u32, _, _) = vec![];
| ^^^ help: use struct literal syntax instead: `Vec { buf: val, len: val }`
error[E0308]: mismatched types
--> $DIR/issue-34334.rs:2:31
|
LL | let sr: Vec<(u32, _, _) = vec![];
| ^^^^^^ expected `bool`, found struct `std::vec::Vec`
|
= note: expected type `bool`
found struct `std::vec::Vec<_>`
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0070]: invalid left-hand side of assignment
--> $DIR/issue-34334.rs:2:29
|
LL | let sr: Vec<(u32, _, _) = vec![];
| --------------- ^
| |
| cannot assign to this expression
error[E0599]: no method named `iter` found for unit type `()` in the current scope
--> $DIR/issue-34334.rs:9:36
error[E0277]: a value of type `std::vec::Vec<(u32, _, _)>` cannot be built from an iterator over elements of type `()`
--> $DIR/issue-34334.rs:4:87
|
LL | let sr2: Vec<(u32, _, _)> = sr.iter().map(|(faction, th_sender, th_receiver)| {}).collect();
| ^^^^ method not found in `()`
| ^^^^^^^ value of type `std::vec::Vec<(u32, _, _)>` cannot be built from `std::iter::Iterator<Item=()>`
|
= help: the trait `std::iter::FromIterator<()>` is not implemented for `std::vec::Vec<(u32, _, _)>`
error: aborting due to 7 previous errors
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0070, E0308, E0423, E0599.
For more information about an error, try `rustc --explain E0070`.
For more information about this error, try `rustc --explain E0277`.