Rollup merge of #47922 - zackmdavis:and_the_case_of_the_unused_field_pattern, r=estebank
correct unused field pattern suggestions  r? @estebank
This commit is contained in:
Manish Goregaokar
GitHub
commit
0ba871254e
5 changed files with 127 additions and 17 deletions
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@ -109,7 +109,7 @@ use self::VarKind::*;
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use hir::def::*;
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use ty::{self, TyCtxt};
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use lint;
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use util::nodemap::NodeMap;
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use util::nodemap::{NodeMap, NodeSet};
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use std::{fmt, usize};
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use std::io::prelude::*;
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@ -244,7 +244,8 @@ struct CaptureInfo {
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#[derive(Copy, Clone, Debug)]
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struct LocalInfo {
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id: NodeId,
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name: ast::Name
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name: ast::Name,
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is_shorthand: bool,
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}
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#[derive(Copy, Clone, Debug)]
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@ -333,6 +334,13 @@ impl<'a, 'tcx> IrMaps<'a, 'tcx> {
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}
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}
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fn variable_is_shorthand(&self, var: Variable) -> bool {
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match self.var_kinds[var.get()] {
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Local(LocalInfo { is_shorthand, .. }) => is_shorthand,
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Arg(..) | CleanExit => false
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}
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}
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fn set_captures(&mut self, node_id: NodeId, cs: Vec<CaptureInfo>) {
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self.capture_info_map.insert(node_id, Rc::new(cs));
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}
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@ -384,8 +392,9 @@ fn visit_local<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, local: &'tcx hir::Local) {
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let name = path1.node;
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ir.add_live_node_for_node(p_id, VarDefNode(sp));
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ir.add_variable(Local(LocalInfo {
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id: p_id,
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name,
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id: p_id,
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name,
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is_shorthand: false,
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}));
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});
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intravisit::walk_local(ir, local);
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@ -393,6 +402,22 @@ fn visit_local<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, local: &'tcx hir::Local) {
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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`
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// rather than `x: x`)
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//
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// FIXME: according to the rust-lang-nursery/rustc-guide book and
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// librustc/README.md, `NodeId`s are to be phased out in favor of
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// `HirId`s; however, we need to match the signature of `each_binding`,
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// 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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}
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}
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}
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pat.each_binding(|bm, p_id, sp, path1| {
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debug!("adding local variable {} from match with bm {:?}",
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p_id, bm);
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@ -400,7 +425,8 @@ fn visit_arm<'a, 'tcx>(ir: &mut IrMaps<'a, 'tcx>, arm: &'tcx hir::Arm) {
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ir.add_live_node_for_node(p_id, VarDefNode(sp));
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ir.add_variable(Local(LocalInfo {
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id: p_id,
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name,
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name: name,
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is_shorthand: shorthand_field_ids.contains(&p_id)
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}));
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})
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}
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@ -1483,17 +1509,26 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
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self.assigned_on_exit(ln, var).is_some()
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};
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let suggest_underscore_msg = format!("consider using `_{}` instead",
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name);
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if is_assigned {
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self.ir.tcx.lint_node_note(lint::builtin::UNUSED_VARIABLES, id, sp,
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&format!("variable `{}` is assigned to, but never used",
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name),
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&format!("to avoid this warning, consider using `_{}` instead",
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name));
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self.ir.tcx
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.lint_node_note(lint::builtin::UNUSED_VARIABLES, id, sp,
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&format!("variable `{}` is assigned to, but never used",
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name),
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&suggest_underscore_msg);
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} else if name != "self" {
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self.ir.tcx.lint_node_note(lint::builtin::UNUSED_VARIABLES, id, sp,
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&format!("unused variable: `{}`", name),
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&format!("to avoid this warning, consider using `_{}` instead",
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name));
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let msg = format!("unused variable: `{}`", name);
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let mut err = self.ir.tcx
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.struct_span_lint_node(lint::builtin::UNUSED_VARIABLES, id, sp, &msg);
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if self.ir.variable_is_shorthand(var) {
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err.span_suggestion(sp, "try ignoring the field",
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format!("{}: _", name));
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} else {
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err.span_suggestion_short(sp, &suggest_underscore_msg,
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format!("_{}", name));
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}
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err.emit()
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}
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}
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true
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@ -13,7 +13,7 @@
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#![allow(non_snake_case)]
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use hir::def_id::DefId;
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use hir::ItemLocalId;
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use hir::{HirId, ItemLocalId};
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use syntax::ast;
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pub use rustc_data_structures::fx::FxHashMap;
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@ -21,10 +21,12 @@ pub use rustc_data_structures::fx::FxHashSet;
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pub type NodeMap<T> = FxHashMap<ast::NodeId, T>;
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pub type DefIdMap<T> = FxHashMap<DefId, T>;
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pub type HirIdMap<T> = FxHashMap<HirId, T>;
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pub type ItemLocalMap<T> = FxHashMap<ItemLocalId, T>;
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pub type NodeSet = FxHashSet<ast::NodeId>;
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pub type DefIdSet = FxHashSet<DefId>;
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pub type HirIdSet = FxHashSet<HirId>;
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pub type ItemLocalSet = FxHashSet<ItemLocalId>;
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pub fn NodeMap<T>() -> NodeMap<T> { FxHashMap() }
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@ -0,0 +1,34 @@
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// must-compile-successfully
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#![warn(unused)] // UI tests pass `-A unused` (#43896)
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struct SoulHistory {
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corridors_of_light: usize,
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hours_are_suns: bool,
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endless_and_singing: bool
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}
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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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corridors_of_light: 5,
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hours_are_suns: true,
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endless_and_singing: true
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};
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if let SoulHistory { corridors_of_light,
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mut hours_are_suns,
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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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}
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@ -0,0 +1,40 @@
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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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22 | 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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13 | #![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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29 | 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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30 | mut hours_are_suns,
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| ^^^^^^^^^^^^^^^^^^
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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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32 | 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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13 | #![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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@ -2,7 +2,7 @@ warning: unused variable: `theOtherTwo`
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--> $DIR/issue-24690.rs:23:9
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23 | let theOtherTwo = 2; //~ WARN should have a snake case name
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| ^^^^^^^^^^^
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| ^^^^^^^^^^^ help: consider using `_theOtherTwo` instead
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note: lint level defined here
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--> $DIR/issue-24690.rs:18:9
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@ -10,7 +10,6 @@ note: lint level defined here
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18 | #![warn(unused)]
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| ^^^^^^
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= note: #[warn(unused_variables)] implied by #[warn(unused)]
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= note: to avoid this warning, consider using `_theOtherTwo` instead
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warning: variable `theTwo` should have a snake case name such as `the_two`
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--> $DIR/issue-24690.rs:22:9
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