Rollup merge of #50327 - varkor:match-unused-struct-field, r=estebank
Display correct unused field suggestion for nested struct patterns Extends https://github.com/rust-lang/rust/pull/47922 by checking more sophisticated patterns (e.g. references, slices, etc.). Before: ``` warning: unused variable: `bar` --> src/main.rs:37:21 | 37 | &Foo::Bar { bar } => true, | ^^^ help: consider using `_bar` instead | = note: #[warn(unused_variables)] on by default ``` After: ``` warning: unused variable: `bar` --> src/main.rs:37:21 | 37 | &Foo::Bar { bar } => true, | ^^^ help: try ignoring the field: `bar: _` | = note: #[warn(unused_variables)] on by default ``` Fixes #50303. r? @estebank
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kennytm
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@ -111,6 +111,7 @@ use ty::{self, TyCtxt};
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use lint;
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use util::nodemap::{NodeMap, NodeSet};
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use std::collections::VecDeque;
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use std::{fmt, usize};
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use std::io::prelude::*;
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use std::io;
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@ -412,18 +413,43 @@ fn visit_local<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, local: &'tcx hir::Local) {
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}
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fn visit_arm<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, arm: &'tcx hir::Arm) {
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for pat in &arm.pats {
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// for struct patterns, take note of which fields used shorthand (`x` rather than `x: x`)
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for mut pat in &arm.pats {
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// For struct patterns, take note of which fields used shorthand
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// (`x` rather than `x: x`).
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//
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// FIXME: according to the rust-lang-nursery/rustc-guide book, `NodeId`s are to be phased
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// out in favor of `HirId`s; however, we need to match the signature of `each_binding`,
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// which uses `NodeIds`.
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// FIXME: according to the rust-lang-nursery/rustc-guide book, `NodeId`s are to be
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// phased out in favor of `HirId`s; however, we need to match the signature of
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// `each_binding`, which uses `NodeIds`.
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let mut shorthand_field_ids = NodeSet();
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if let hir::PatKind::Struct(_, ref fields, _) = pat.node {
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for field in fields {
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if field.node.is_shorthand {
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shorthand_field_ids.insert(field.node.pat.id);
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let mut pats = VecDeque::new();
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pats.push_back(pat);
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while let Some(pat) = pats.pop_front() {
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use hir::PatKind::*;
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match pat.node {
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Binding(_, _, _, ref inner_pat) => {
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pats.extend(inner_pat.iter());
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}
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Struct(_, ref fields, _) => {
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for field in fields {
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if field.node.is_shorthand {
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shorthand_field_ids.insert(field.node.pat.id);
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}
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}
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}
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Ref(ref inner_pat, _) |
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Box(ref inner_pat) => {
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pats.push_back(inner_pat);
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}
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TupleStruct(_, ref inner_pats, _) |
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Tuple(ref inner_pats, _) => {
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pats.extend(inner_pats.iter());
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}
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Slice(ref pre_pats, ref inner_pat, ref post_pats) => {
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pats.extend(pre_pats.iter());
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pats.extend(inner_pat.iter());
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pats.extend(post_pats.iter());
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}
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_ => {}
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}
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}
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@ -10,6 +10,8 @@
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// compile-pass
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#![feature(box_syntax)]
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#![feature(box_patterns)]
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#![warn(unused)] // UI tests pass `-A unused` (#43896)
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struct SoulHistory {
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@ -18,6 +20,13 @@ struct SoulHistory {
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endless_and_singing: bool
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}
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#[derive(Clone, Copy)]
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enum Large {
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Suit { case: () }
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}
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struct Tuple(Large, ());
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fn main() {
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let i_think_continually = 2;
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let who_from_the_womb_remembered = SoulHistory {
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@ -31,4 +40,38 @@ fn main() {
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endless_and_singing: true } = who_from_the_womb_remembered {
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hours_are_suns = false;
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}
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let bag = Large::Suit {
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case: ()
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};
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// Plain struct
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match bag {
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Large::Suit { case } => {}
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};
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// Referenced struct
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match &bag {
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&Large::Suit { case } => {}
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};
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// Boxed struct
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match box bag {
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box Large::Suit { case } => {}
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};
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// Tuple with struct
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match (bag,) {
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(Large::Suit { case },) => {}
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};
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// Slice with struct
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match [bag] {
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[Large::Suit { case }] => {}
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};
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// Tuple struct with struct
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match Tuple(bag, ()) {
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Tuple(Large::Suit { case }, ()) => {}
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};
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}
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@ -1,24 +1,24 @@
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warning: unused variable: `i_think_continually`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:22:9
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:31:9
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LL | let i_think_continually = 2;
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| ^^^^^^^^^^^^^^^^^^^ help: consider using `_i_think_continually` instead
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note: lint level defined here
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:13:9
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:15:9
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LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
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| ^^^^^^
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= note: #[warn(unused_variables)] implied by #[warn(unused)]
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warning: unused variable: `corridors_of_light`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:29:26
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:38:26
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LL | if let SoulHistory { corridors_of_light,
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| ^^^^^^^^^^^^^^^^^^ help: try ignoring the field: `corridors_of_light: _`
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warning: variable `hours_are_suns` is assigned to, but never used
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:30:26
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:39:26
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LL | mut hours_are_suns,
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| ^^^^^^^^^^^^^^^^^^
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@ -26,15 +26,51 @@ LL | mut hours_are_suns,
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= note: consider using `_hours_are_suns` instead
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warning: value assigned to `hours_are_suns` is never read
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:32:9
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:41:9
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LL | hours_are_suns = false;
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| ^^^^^^^^^^^^^^
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note: lint level defined here
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:13:9
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:15:9
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LL | #![warn(unused)] // UI tests pass `-A unused` (#43896)
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| ^^^^^^
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= note: #[warn(unused_assignments)] implied by #[warn(unused)]
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:50:23
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LL | Large::Suit { case } => {}
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| ^^^^ help: try ignoring the field: `case: _`
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:55:24
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LL | &Large::Suit { case } => {}
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| ^^^^ help: try ignoring the field: `case: _`
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:60:27
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LL | box Large::Suit { case } => {}
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| ^^^^ help: try ignoring the field: `case: _`
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:65:24
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LL | (Large::Suit { case },) => {}
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| ^^^^ help: try ignoring the field: `case: _`
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:70:24
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LL | [Large::Suit { case }] => {}
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| ^^^^ help: try ignoring the field: `case: _`
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warning: unused variable: `case`
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--> $DIR/issue-47390-unused-variable-in-struct-pattern.rs:75:29
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LL | Tuple(Large::Suit { case }, ()) => {}
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| ^^^^ help: try ignoring the field: `case: _`
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