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Suggest Variant(..) if all of the mentioned fields are _

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This commit is contained in:
Camelid 2020-12-18 19:51:39 -08:00
parent 5fe61a79cc
commit f3d9df54ee
4 changed files with 34 additions and 19 deletions
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33
compiler/rustc_typeck/src/check/pat.rs
View File

@ -20,7 +20,6 @@ use rustc_trait_selection::traits::{ObligationCause, Pattern};
use std::cmp;
use std::collections::hash_map::Entry::{Occupied, Vacant};
use std::iter;
use super::report_unexpected_variant_res;
@ -1048,26 +1047,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
} else {
pat_span.with_hi(pat_span.hi() - BytePos(1)).shrink_to_hi()
};
let all_fields_span = match subpats {
[] => after_fields_span,
[field] => field.span,
[first, .., last] => first.span.to(last.span),
};
// Check if all the fields in the pattern are wildcards.
let all_wildcards = subpats.iter().all(|pat| matches!(pat.kind, PatKind::Wild));
let mut wildcard_sugg = vec!["_"; fields.len() - subpats.len()].join(", ");
if !subpats.is_empty() {
wildcard_sugg = String::from(", ") + &wildcard_sugg;
}
let rest_sugg = if subpats.is_empty() { "..".to_owned() } else { ", ..".to_owned() };
err.span_suggestion(
after_fields_span,
"use `_` to explicitly ignore each field",
wildcard_sugg,
Applicability::MaybeIncorrect,
);
err.span_suggestion(
after_fields_span,
"use `..` to ignore all unmentioned fields",
rest_sugg,
Applicability::MaybeIncorrect,
);
if subpats.is_empty() || all_wildcards {
err.span_suggestion(
all_fields_span,
"use `..` to ignore all unmentioned fields",
String::from(".."),
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion(
after_fields_span,
"use `..` to ignore all unmentioned fields",
String::from(", .."),
Applicability::MaybeIncorrect,
);
}
}
err.emit();

8
src/test/ui/destructuring-assignment/tuple_struct_destructure_fail.stderr
View File

@ -38,8 +38,8 @@ LL | TupleStruct(_, _) = TupleStruct(1, 2);
| ^^^
help: use `..` to ignore all unmentioned fields
|
LL | TupleStruct(_, ..) = TupleStruct(1, 2);
| ^^^^
LL | TupleStruct(..) = TupleStruct(1, 2);
| ^^
error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
--> $DIR/tuple_struct_destructure_fail.rs:34:5
@ -65,8 +65,8 @@ LL | Enum::SingleVariant(_, _) = Enum::SingleVariant(1, 2);
| ^^^
help: use `..` to ignore all unmentioned fields
|
LL | Enum::SingleVariant(_, ..) = Enum::SingleVariant(1, 2);
| ^^^^
LL | Enum::SingleVariant(..) = Enum::SingleVariant(1, 2);
| ^^
error[E0070]: invalid left-hand side of assignment
--> $DIR/tuple_struct_destructure_fail.rs:40:12

4
src/test/ui/match/match-pattern-field-mismatch.stderr
View File

@ -13,8 +13,8 @@ LL | Color::Rgb(_, _, _) => { }
| ^^^
help: use `..` to ignore all unmentioned fields
|
LL | Color::Rgb(_, _, ..) => { }
| ^^^^
LL | Color::Rgb(..) => { }
| ^^
error: aborting due to previous error

8
src/test/ui/pattern/pat-tuple-underfield.stderr
View File

@ -40,8 +40,8 @@ LL | S(_, _) => {}
| ^^^
help: use `..` to ignore all unmentioned fields
|
LL | S(_, ..) => {}
| ^^^^
LL | S(..) => {}
| ^^
error[E0023]: this pattern has 0 fields, but the corresponding tuple struct has 2 fields
--> $DIR/pat-tuple-underfield.rs:20:9
@ -94,8 +94,8 @@ LL | E::S(_, _) => {}
| ^^^
help: use `..` to ignore all unmentioned fields
|
LL | E::S(_, ..) => {}
| ^^^^
LL | E::S(..) => {}
| ^^
error[E0023]: this pattern has 0 fields, but the corresponding tuple variant has 2 fields
--> $DIR/pat-tuple-underfield.rs:39:9