diff options
| -rw-r--r-- | clippy_lints/src/matches/mod.rs | 13 | ||||
| -rw-r--r-- | clippy_lints/src/matches/significant_drop_in_scrutinee.rs | 111 | ||||
| -rw-r--r-- | tests/ui/significant_drop_in_scrutinee.rs | 26 | ||||
| -rw-r--r-- | tests/ui/significant_drop_in_scrutinee.stderr | 29 |
4 files changed, 149 insertions, 30 deletions
diff --git a/clippy_lints/src/matches/mod.rs b/clippy_lints/src/matches/mod.rs index bf7156cc53e..22a299ae3d8 100644 --- a/clippy_lints/src/matches/mod.rs +++ b/clippy_lints/src/matches/mod.rs @@ -1019,6 +1019,7 @@ impl_lint_pass!(Matches => [ ]); impl<'tcx> LateLintPass<'tcx> for Matches { + #[expect(clippy::too_many_lines)] fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { if is_direct_expn_of(expr.span, "matches").is_none() && in_external_macro(cx.sess(), expr.span) { return; @@ -1037,7 +1038,7 @@ impl<'tcx> LateLintPass<'tcx> for Matches { return; } if matches!(source, MatchSource::Normal | MatchSource::ForLoopDesugar) { - significant_drop_in_scrutinee::check(cx, expr, ex, arms, source); + significant_drop_in_scrutinee::check_match(cx, expr, ex, arms, source); } collapsible_match::check_match(cx, arms, &self.msrv); @@ -1084,6 +1085,7 @@ impl<'tcx> LateLintPass<'tcx> for Matches { } } else if let Some(if_let) = higher::IfLet::hir(cx, expr) { collapsible_match::check_if_let(cx, if_let.let_pat, if_let.if_then, if_let.if_else, &self.msrv); + significant_drop_in_scrutinee::check_if_let(cx, expr, if_let.let_expr, if_let.if_then, if_let.if_else); if !from_expansion { if let Some(else_expr) = if_let.if_else { if self.msrv.meets(msrvs::MATCHES_MACRO) { @@ -1126,8 +1128,13 @@ impl<'tcx> LateLintPass<'tcx> for Matches { ); needless_match::check_if_let(cx, expr, &if_let); } - } else if !from_expansion { - redundant_pattern_match::check(cx, expr); + } else { + if let Some(while_let) = higher::WhileLet::hir(expr) { + significant_drop_in_scrutinee::check_while_let(cx, expr, while_let.let_expr, while_let.if_then); + } + if !from_expansion { + redundant_pattern_match::check(cx, expr); + } } } diff --git a/clippy_lints/src/matches/significant_drop_in_scrutinee.rs b/clippy_lints/src/matches/significant_drop_in_scrutinee.rs index 2f72e59834f..9047c9627d9 100644 --- a/clippy_lints/src/matches/significant_drop_in_scrutinee.rs +++ b/clippy_lints/src/matches/significant_drop_in_scrutinee.rs @@ -16,7 +16,7 @@ use rustc_span::Span; use super::SIGNIFICANT_DROP_IN_SCRUTINEE; -pub(super) fn check<'tcx>( +pub(super) fn check_match<'tcx>( cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, scrutinee: &'tcx Expr<'_>, @@ -27,10 +27,89 @@ pub(super) fn check<'tcx>( return; } - let (suggestions, message) = has_significant_drop_in_scrutinee(cx, scrutinee, source); + let scrutinee = match (source, &scrutinee.kind) { + (MatchSource::ForLoopDesugar, ExprKind::Call(_, [e])) => e, + _ => scrutinee, + }; + + let message = if source == MatchSource::Normal { + "temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression" + } else { + "temporary with significant `Drop` in `for` loop condition will live until the end of the `for` expression" + }; + + let arms = arms.iter().map(|arm| arm.body).collect::<Vec<_>>(); + + check(cx, expr, scrutinee, &arms, message, Suggestion::Emit); +} + +pub(super) fn check_if_let<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx Expr<'tcx>, + scrutinee: &'tcx Expr<'_>, + if_then: &'tcx Expr<'_>, + if_else: Option<&'tcx Expr<'_>>, +) { + if is_lint_allowed(cx, SIGNIFICANT_DROP_IN_SCRUTINEE, expr.hir_id) { + return; + } + + let message = + "temporary with significant `Drop` in `if let` scrutinee will live until the end of the `if let` expression"; + + if let Some(if_else) = if_else { + check(cx, expr, scrutinee, &[if_then, if_else], message, Suggestion::Emit); + } else { + check(cx, expr, scrutinee, &[if_then], message, Suggestion::Emit); + } +} + +pub(super) fn check_while_let<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx Expr<'tcx>, + scrutinee: &'tcx Expr<'_>, + body: &'tcx Expr<'_>, +) { + if is_lint_allowed(cx, SIGNIFICANT_DROP_IN_SCRUTINEE, expr.hir_id) { + return; + } + + check( + cx, + expr, + scrutinee, + &[body], + "temporary with significant `Drop` in `while let` scrutinee will live until the end of the `while let` expression", + // Don't emit wrong suggestions: We cannot fix the significant drop in the `while let` scrutinee by simply + // moving it out. We need to change the `while` to a `loop` instead. + Suggestion::DontEmit, + ); +} + +#[derive(Copy, Clone, Debug)] +enum Suggestion { + Emit, + DontEmit, +} + +fn check<'tcx>( + cx: &LateContext<'tcx>, + expr: &'tcx Expr<'tcx>, + scrutinee: &'tcx Expr<'_>, + arms: &[&'tcx Expr<'_>], + message: &'static str, + sugg: Suggestion, +) { + let mut helper = SigDropHelper::new(cx); + let suggestions = helper.find_sig_drop(scrutinee); + for found in suggestions { span_lint_and_then(cx, SIGNIFICANT_DROP_IN_SCRUTINEE, found.found_span, message, |diag| { - set_diagnostic(diag, cx, expr, found); + match sugg { + Suggestion::Emit => set_suggestion(diag, cx, expr, found), + Suggestion::DontEmit => (), + } + let s = Span::new(expr.span.hi(), expr.span.hi(), expr.span.ctxt(), None); diag.span_label(s, "temporary lives until here"); for span in has_significant_drop_in_arms(cx, arms) { @@ -41,7 +120,7 @@ pub(super) fn check<'tcx>( } } -fn set_diagnostic<'tcx>(diag: &mut Diag<'_, ()>, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, found: FoundSigDrop) { +fn set_suggestion<'tcx>(diag: &mut Diag<'_, ()>, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, found: FoundSigDrop) { let original = snippet(cx, found.found_span, ".."); let trailing_indent = " ".repeat(indent_of(cx, found.found_span).unwrap_or(0)); @@ -79,26 +158,6 @@ fn set_diagnostic<'tcx>(diag: &mut Diag<'_, ()>, cx: &LateContext<'tcx>, expr: & ); } -/// If the expression is an `ExprKind::Match`, check if the scrutinee has a significant drop that -/// may have a surprising lifetime. -fn has_significant_drop_in_scrutinee<'tcx>( - cx: &LateContext<'tcx>, - scrutinee: &'tcx Expr<'tcx>, - source: MatchSource, -) -> (Vec<FoundSigDrop>, &'static str) { - let mut helper = SigDropHelper::new(cx); - let scrutinee = match (source, &scrutinee.kind) { - (MatchSource::ForLoopDesugar, ExprKind::Call(_, [e])) => e, - _ => scrutinee, - }; - let message = if source == MatchSource::Normal { - "temporary with significant `Drop` in `match` scrutinee will live until the end of the `match` expression" - } else { - "temporary with significant `Drop` in `for` loop condition will live until the end of the `for` expression" - }; - (helper.find_sig_drop(scrutinee), message) -} - struct SigDropChecker<'a, 'tcx> { seen_types: FxHashSet<Ty<'tcx>>, cx: &'a LateContext<'tcx>, @@ -428,10 +487,10 @@ impl<'a, 'tcx> ArmSigDropHelper<'a, 'tcx> { } } -fn has_significant_drop_in_arms<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) -> FxHashSet<Span> { +fn has_significant_drop_in_arms<'tcx>(cx: &LateContext<'tcx>, arms: &[&'tcx Expr<'_>]) -> FxHashSet<Span> { let mut helper = ArmSigDropHelper::new(cx); for arm in arms { - helper.visit_expr(arm.body); + helper.visit_expr(arm); } helper.found_sig_drop_spans } diff --git a/tests/ui/significant_drop_in_scrutinee.rs b/tests/ui/significant_drop_in_scrutinee.rs index 8ee15440ccf..0db6fbfb7be 100644 --- a/tests/ui/significant_drop_in_scrutinee.rs +++ b/tests/ui/significant_drop_in_scrutinee.rs @@ -801,4 +801,30 @@ fn should_not_trigger_lint_with_explicit_drop() { } } +fn should_trigger_lint_in_if_let() { + let mutex = Mutex::new(vec![1]); + + if let Some(val) = mutex.lock().unwrap().first().copied() { + //~^ ERROR: temporary with significant `Drop` in `if let` scrutinee will live until the + //~| NOTE: this might lead to deadlocks or other unexpected behavior + println!("{}", val); + } + + // Should not trigger lint without the final `copied()`, because we actually hold a reference + // (i.e., the `val`) to the locked data. + if let Some(val) = mutex.lock().unwrap().first() { + println!("{}", val); + }; +} + +fn should_trigger_lint_in_while_let() { + let mutex = Mutex::new(vec![1]); + + while let Some(val) = mutex.lock().unwrap().pop() { + //~^ ERROR: temporary with significant `Drop` in `while let` scrutinee will live until the + //~| NOTE: this might lead to deadlocks or other unexpected behavior + println!("{}", val); + } +} + fn main() {} diff --git a/tests/ui/significant_drop_in_scrutinee.stderr b/tests/ui/significant_drop_in_scrutinee.stderr index 4a483e79d8a..c0c93cd10c0 100644 --- a/tests/ui/significant_drop_in_scrutinee.stderr +++ b/tests/ui/significant_drop_in_scrutinee.stderr @@ -541,5 +541,32 @@ LL ~ let value = mutex.lock().unwrap()[0]; LL ~ for val in [value, 2] { | -error: aborting due to 27 previous errors +error: temporary with significant `Drop` in `if let` scrutinee will live until the end of the `if let` expression + --> tests/ui/significant_drop_in_scrutinee.rs:807:24 + | +LL | if let Some(val) = mutex.lock().unwrap().first().copied() { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +... +LL | } + | - temporary lives until here + | + = note: this might lead to deadlocks or other unexpected behavior +help: try moving the temporary above the match + | +LL ~ let value = mutex.lock().unwrap().first().copied(); +LL ~ if let Some(val) = value { + | + +error: temporary with significant `Drop` in `while let` scrutinee will live until the end of the `while let` expression + --> tests/ui/significant_drop_in_scrutinee.rs:823:27 + | +LL | while let Some(val) = mutex.lock().unwrap().pop() { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ +... +LL | } + | - temporary lives until here + | + = note: this might lead to deadlocks or other unexpected behavior + +error: aborting due to 29 previous errors |