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Correct unused field warning on &struct match

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This commit is contained in:
varkor 2018-04-30 00:40:11 +01:00
parent a9975254ee
commit cc53db8bf9
3 changed files with 41 additions and 13 deletions
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28
src/librustc/middle/liveness.rs
View File

@ -412,18 +412,28 @@ fn visit_local<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, local: &'tcx hir::Local) {
}
fn visit_arm<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, arm: &'tcx hir::Arm) {
for pat in &arm.pats {
// for struct patterns, take note of which fields used shorthand (`x` rather than `x: x`)
for mut pat in &arm.pats {
// For struct patterns, take note of which fields used shorthand
// (`x` rather than `x: x`).
//
// FIXME: according to the rust-lang-nursery/rustc-guide book, `NodeId`s are to be phased
// out in favor of `HirId`s; however, we need to match the signature of `each_binding`,
// which uses `NodeIds`.
// FIXME: according to the rust-lang-nursery/rustc-guide book, `NodeId`s are to be
// phased out in favor of `HirId`s; however, we need to match the signature of
// `each_binding`, which uses `NodeIds`.
let mut shorthand_field_ids = NodeSet();
if let hir::PatKind::Struct(_, ref fields, _) = pat.node {
for field in fields {
if field.node.is_shorthand {
shorthand_field_ids.insert(field.node.pat.id);
loop {
match pat.node {
hir::PatKind::Struct(_, ref fields, _) => {
for field in fields {
if field.node.is_shorthand {
shorthand_field_ids.insert(field.node.pat.id);
}
}
break;
}
hir::PatKind::Ref(ref deref_pat, _) => {
pat = deref_pat;
}
_ => break
}
}

12
src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.rs
View File

@ -18,6 +18,10 @@ struct SoulHistory {
endless_and_singing: bool
}
enum Large {
Suit { case: () }
}
fn main() {
let i_think_continually = 2;
let who_from_the_womb_remembered = SoulHistory {
@ -31,4 +35,12 @@ fn main() {
endless_and_singing: true } = who_from_the_womb_remembered {
hours_are_suns = false;
}
let bag = &Large::Suit {
case: ()
};
match bag {
&Large::Suit { case } => {}
};
}

14
src/test/ui/lint/issue-47390-unused-variable-in-struct-pattern.stderr
View File

@ -1,5 +1,5 @@
warning: unused variable: `i_think_continually`
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:22:9
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:26:9
|
LL | let i_think_continually = 2;
| ^^^^^^^^^^^^^^^^^^^ help: consider using `_i_think_continually` instead
@ -12,13 +12,13 @@ LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
= note: #[warn(unused_variables)] implied by #[warn(unused)]
warning: unused variable: `corridors_of_light`
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:29:26
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:33:26
|
LL | if let SoulHistory { corridors_of_light,
| ^^^^^^^^^^^^^^^^^^ help: try ignoring the field: `corridors_of_light: _`
warning: variable `hours_are_suns` is assigned to, but never used
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:30:26
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:34:26
|
LL | mut hours_are_suns,
| ^^^^^^^^^^^^^^^^^^
@ -26,7 +26,7 @@ LL | mut hours_are_suns,
= note: consider using `_hours_are_suns` instead
warning: value assigned to `hours_are_suns` is never read
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:32:9
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:36:9
|
LL | hours_are_suns = false;
| ^^^^^^^^^^^^^^
@ -38,3 +38,9 @@ LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
| ^^^^^^
= note: #[warn(unused_assignments)] implied by #[warn(unused)]
warning: unused variable: `case`
--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:44:24
|
LL | &Large::Suit { case } => {}
| ^^^^ help: try ignoring the field: `case: _`