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https://github.com/rust-lang/rust-clippy
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When setting suggestion, add suggestion for MoveAndClone for non-ref
When trying to set the current suggestion, if the type of the expression is not a reference and it is not trivially pure clone copy, we should still trigger and emit a lint message. Since this fix may require cloning an expensive-to-clone type, do not attempt to offer a suggested fix. This change means that matches generated from TryDesugar and AwaitDesugar would normally trigger a lint, but they are out of scope for this lint, so we will explicitly ignore matches with sources of TryDesugar or AwaitDesugar. changelog: Update for [`significant_drop_in_scrutinee`] to correctly emit lint messages for cases where the type is not a reference and not trivially pure clone copy.
This commit is contained in:
Preston From
parent
3cc50a4a08
commit
e33d87d4a0
4 changed files with 134 additions and 75 deletions
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@ -4,7 +4,7 @@ use clippy_utils::get_attr;
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use clippy_utils::source::{indent_of, snippet};
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use rustc_errors::{Applicability, Diagnostic};
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use rustc_hir::intravisit::{walk_expr, Visitor};
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use rustc_hir::{Expr, ExprKind};
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use rustc_hir::{Expr, ExprKind, MatchSource};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::ty::subst::GenericArgKind;
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use rustc_middle::ty::{Ty, TypeAndMut};
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@ -154,9 +154,17 @@ fn has_significant_drop_in_scrutinee<'tcx, 'a>(
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cx: &'a LateContext<'tcx>,
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expr: &'tcx Expr<'tcx>,
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) -> Option<Vec<FoundSigDrop>> {
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let mut helper = SigDropHelper::new(cx);
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match expr.kind {
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ExprKind::Match(match_expr, _, _) => helper.find_sig_drop(match_expr),
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ExprKind::Match(match_expr, _, source) => {
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match source {
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MatchSource::Normal | MatchSource::ForLoopDesugar => {
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let mut helper = SigDropHelper::new(cx);
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helper.find_sig_drop(match_expr)
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},
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// MatchSource of TryDesugar or AwaitDesugar is out of scope for this lint
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MatchSource::TryDesugar | MatchSource::AwaitDesugar => None,
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}
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},
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_ => None,
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}
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}
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@ -213,6 +221,19 @@ impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
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self.sig_drop_spans.take()
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}
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fn replace_current_sig_drop(
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&mut self,
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found_span: Span,
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is_unit_return_val: bool,
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lint_suggestion: LintSuggestion,
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) {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span,
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is_unit_return_val,
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lint_suggestion,
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});
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}
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/// This will try to set the current suggestion (so it can be moved into the suggestions vec
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/// later). If `allow_move_and_clone` is false, the suggestion *won't* be set -- this gives us
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/// an opportunity to look for another type in the chain that will be trivially copyable.
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@ -229,25 +250,15 @@ impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
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// but let's avoid any chance of an ICE
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if let Some(TypeAndMut { ty, .. }) = ty.builtin_deref(true) {
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if ty.is_trivially_pure_clone_copy() {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveAndDerefToCopy,
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});
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self.replace_current_sig_drop(expr.span, false, LintSuggestion::MoveAndDerefToCopy);
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} else if allow_move_and_clone {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveAndClone,
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});
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self.replace_current_sig_drop(expr.span, false, LintSuggestion::MoveAndClone);
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}
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}
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} else if ty.is_trivially_pure_clone_copy() {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveOnly,
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});
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self.replace_current_sig_drop(expr.span, false, LintSuggestion::MoveOnly);
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} else if allow_move_and_clone {
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self.replace_current_sig_drop(expr.span, false, LintSuggestion::MoveAndClone);
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}
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}
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@ -279,11 +290,7 @@ impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
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// If either side had a significant drop, suggest moving the entire scrutinee to avoid
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// unnecessary copies and to simplify cases where both sides have significant drops.
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if self.has_significant_drop {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: span,
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is_unit_return_val,
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lint_suggestion: LintSuggestion::MoveOnly,
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});
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self.replace_current_sig_drop(span, is_unit_return_val, LintSuggestion::MoveOnly);
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}
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self.special_handling_for_binary_op = false;
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@ -2073,7 +2073,8 @@ static TEST_ITEM_NAMES_CACHE: SyncOnceCell<Mutex<FxHashMap<LocalDefId, Vec<Symbo
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fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
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let cache = TEST_ITEM_NAMES_CACHE.get_or_init(|| Mutex::new(FxHashMap::default()));
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let mut map: MutexGuard<'_, FxHashMap<LocalDefId, Vec<Symbol>>> = cache.lock().unwrap();
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match map.entry(module) {
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let value = map.entry(module);
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match value {
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Entry::Occupied(entry) => f(entry.get()),
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Entry::Vacant(entry) => {
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let mut names = Vec::new();
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@ -7,8 +7,10 @@
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#![allow(unused_assignments)]
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#![allow(dead_code)]
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use std::num::ParseIntError;
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use std::ops::Deref;
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use std::sync::atomic::{AtomicU64, Ordering};
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use std::sync::RwLock;
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use std::sync::{Mutex, MutexGuard};
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struct State {}
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@ -552,4 +554,41 @@ fn should_not_cause_stack_overflow() {
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}
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}
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fn should_not_produce_lint_for_try_desugar() -> Result<u64, ParseIntError> {
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// TryDesugar (i.e. using `?` for a Result type) will turn into a match but is out of scope
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// for this lint
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let rwlock = RwLock::new("1".to_string());
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let result = rwlock.read().unwrap().parse::<u64>()?;
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println!("{}", result);
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rwlock.write().unwrap().push('2');
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Ok(result)
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}
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struct ResultReturner {
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s: String,
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}
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impl ResultReturner {
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fn to_number(&self) -> Result<i64, ParseIntError> {
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self.s.parse::<i64>()
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}
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}
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fn should_trigger_lint_for_non_ref_move_and_clone_suggestion() {
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let rwlock = RwLock::<ResultReturner>::new(ResultReturner { s: "1".to_string() });
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match rwlock.read().unwrap().to_number() {
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Ok(n) => println!("Converted to number: {}", n),
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Err(e) => println!("Could not convert {} to number", e),
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};
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}
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fn should_trigger_lint_for_read_write_lock_for_loop() {
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// For-in loops desugar to match expressions and are prone to the type of deadlock this lint is
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// designed to look for.
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let rwlock = RwLock::<Vec<String>>::new(vec!["1".to_string()]);
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for s in rwlock.read().unwrap().iter() {
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println!("{}", s);
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}
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}
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fn main() {}
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@ -1,5 +1,5 @@
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:57:11
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--> $DIR/significant_drop_in_scrutinee.rs:59:11
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LL | match mutex.lock().unwrap().foo() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -12,7 +12,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:130:11
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--> $DIR/significant_drop_in_scrutinee.rs:132:11
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LL | match s.lock_m().get_the_value() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -24,7 +24,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:151:11
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--> $DIR/significant_drop_in_scrutinee.rs:153:11
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LL | match s.lock_m_m().get_the_value() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -36,7 +36,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:199:11
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--> $DIR/significant_drop_in_scrutinee.rs:201:11
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LL | match counter.temp_increment().len() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -48,7 +48,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:222:16
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--> $DIR/significant_drop_in_scrutinee.rs:224:16
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LL | match (mutex1.lock().unwrap().s.len(), true) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -60,7 +60,7 @@ LL ~ match (value, true) {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:231:22
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--> $DIR/significant_drop_in_scrutinee.rs:233:22
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LL | match (true, mutex1.lock().unwrap().s.len(), true) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -72,7 +72,7 @@ LL ~ match (true, value, true) {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:241:16
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--> $DIR/significant_drop_in_scrutinee.rs:243:16
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LL | match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -84,7 +84,7 @@ LL ~ match (value, true, mutex2.lock().unwrap().s.len()) {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:241:54
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--> $DIR/significant_drop_in_scrutinee.rs:243:54
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LL | match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -96,19 +96,19 @@ LL ~ match (mutex1.lock().unwrap().s.len(), true, value) {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:252:15
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--> $DIR/significant_drop_in_scrutinee.rs:254:15
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LL | match mutex3.lock().unwrap().s.as_str() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:262:22
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--> $DIR/significant_drop_in_scrutinee.rs:264:22
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LL | match (true, mutex3.lock().unwrap().s.as_str()) {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:281:11
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--> $DIR/significant_drop_in_scrutinee.rs:283:11
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LL | match mutex.lock().unwrap().s.len() > 1 {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -120,7 +120,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:288:11
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--> $DIR/significant_drop_in_scrutinee.rs:290:11
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LL | match 1 < mutex.lock().unwrap().s.len() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -132,7 +132,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:306:11
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--> $DIR/significant_drop_in_scrutinee.rs:308:11
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LL | match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -144,7 +144,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:317:11
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--> $DIR/significant_drop_in_scrutinee.rs:319:11
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LL | match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -156,7 +156,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:352:11
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--> $DIR/significant_drop_in_scrutinee.rs:354:11
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LL | match get_mutex_guard().s.len() > 1 {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -168,7 +168,7 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:369:11
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--> $DIR/significant_drop_in_scrutinee.rs:371:11
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LL | match match i {
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| ___________^
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@ -191,7 +191,7 @@ LL + .len()
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...
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:395:11
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--> $DIR/significant_drop_in_scrutinee.rs:397:11
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LL | match if i > 1 {
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| ___________^
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@ -214,7 +214,7 @@ LL + .s
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...
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:449:11
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--> $DIR/significant_drop_in_scrutinee.rs:451:11
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LL | match s.lock().deref().deref() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^
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@ -226,13 +226,13 @@ LL ~ match value {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:477:11
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--> $DIR/significant_drop_in_scrutinee.rs:479:11
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LL | match s.lock().deref().deref() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:496:11
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--> $DIR/significant_drop_in_scrutinee.rs:498:11
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LL | match mutex.lock().unwrap().i = i {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -244,7 +244,7 @@ LL ~ match () {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:502:11
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--> $DIR/significant_drop_in_scrutinee.rs:504:11
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LL | match i = mutex.lock().unwrap().i {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -256,7 +256,7 @@ LL ~ match () {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:508:11
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--> $DIR/significant_drop_in_scrutinee.rs:510:11
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LL | match mutex.lock().unwrap().i += 1 {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -268,7 +268,7 @@ LL ~ match () {
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:514:11
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--> $DIR/significant_drop_in_scrutinee.rs:516:11
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LL | match i += mutex.lock().unwrap().i {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@ -279,5 +279,17 @@ LL ~ i += mutex.lock().unwrap().i;
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LL ~ match () {
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error: aborting due to 23 previous errors
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:579:11
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LL | match rwlock.read().unwrap().to_number() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: temporary with significant drop in match scrutinee
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--> $DIR/significant_drop_in_scrutinee.rs:589:14
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LL | for s in rwlock.read().unwrap().iter() {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: aborting due to 25 previous errors
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