diff --git a/clippy_lints/src/significant_drop_tightening.rs b/clippy_lints/src/significant_drop_tightening.rs index f4e56489b096f..fffa8a380c2f8 100644 --- a/clippy_lints/src/significant_drop_tightening.rs +++ b/clippy_lints/src/significant_drop_tightening.rs @@ -1,10 +1,10 @@ use clippy_utils::{ diagnostics::span_lint_and_then, - get_attr, + expr_or_init, get_attr, path_to_local, source::{indent_of, snippet}, }; -use rustc_data_structures::fx::{FxHashMap, FxHashSet}; -use rustc_errors::{Applicability, Diagnostic}; +use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap}; +use rustc_errors::Applicability; use rustc_hir::{ self as hir, intravisit::{walk_expr, Visitor}, @@ -13,6 +13,7 @@ use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_middle::ty::{subst::GenericArgKind, Ty, TypeAndMut}; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::{symbol::Ident, Span, DUMMY_SP}; +use std::borrow::Cow; declare_clippy_lint! { /// ### What it does @@ -56,255 +57,102 @@ impl_lint_pass!(SignificantDropTightening<'_> => [SIGNIFICANT_DROP_TIGHTENING]); #[derive(Default)] pub struct SignificantDropTightening<'tcx> { + apas: FxIndexMap, /// Auxiliary structure used to avoid having to verify the same type multiple times. seen_types: FxHashSet>, type_cache: FxHashMap, bool>, } -impl<'tcx> SignificantDropTightening<'tcx> { - /// Unifies the statements of a block with its return expression. - fn all_block_stmts<'ret, 'rslt, 'stmts>( - block_stmts: &'stmts [hir::Stmt<'tcx>], - dummy_ret_stmt: Option<&'ret hir::Stmt<'tcx>>, - ) -> impl Iterator> - where - 'ret: 'rslt, - 'stmts: 'rslt, - { - block_stmts.iter().chain(dummy_ret_stmt) - } - - /// Searches for at least one statement that could slow down the release of a significant drop. - fn at_least_one_stmt_is_expensive<'stmt>(stmts: impl Iterator>) -> bool - where - 'tcx: 'stmt, - { - for stmt in stmts { - match stmt.kind { - hir::StmtKind::Expr(expr) if let hir::ExprKind::Path(_) = expr.kind => {} - hir::StmtKind::Local(local) if let Some(expr) = local.init - && let hir::ExprKind::Path(_) = expr.kind => {}, - _ => return true - }; - } - false - } - - /// Verifies if the expression is of type `drop(some_lock_path)` to assert that the temporary - /// is already being dropped before the end of its scope. - fn has_drop(expr: &'tcx hir::Expr<'_>, init_bind_ident: Ident) -> bool { - if let hir::ExprKind::Call(fun, args) = expr.kind - && let hir::ExprKind::Path(hir::QPath::Resolved(_, fun_path)) = &fun.kind - && let [fun_ident, ..] = fun_path.segments - && fun_ident.ident.name == rustc_span::sym::drop - && let [first_arg, ..] = args - && let hir::ExprKind::Path(hir::QPath::Resolved(_, arg_path)) = &first_arg.kind - && let [first_arg_ps, .. ] = arg_path.segments - { - first_arg_ps.ident == init_bind_ident - } - else { - false - } - } - - /// Tries to find types marked with `#[has_significant_drop]` of an expression `expr` that is - /// originated from `stmt` and then performs common logic on `sdap`. - fn modify_sdap_if_sig_drop_exists( +impl<'tcx> LateLintPass<'tcx> for SignificantDropTightening<'tcx> { + fn check_fn( &mut self, cx: &LateContext<'tcx>, - expr: &'tcx hir::Expr<'_>, - idx: usize, - sdap: &mut SigDropAuxParams, - stmt: &hir::Stmt<'_>, - cb: impl Fn(&mut SigDropAuxParams), + _: hir::intravisit::FnKind<'_>, + _: &hir::FnDecl<'_>, + body: &'tcx hir::Body<'_>, + _: Span, + _: hir::def_id::LocalDefId, ) { - let mut sig_drop_finder = SigDropFinder::new(cx, &mut self.seen_types, &mut self.type_cache); - sig_drop_finder.visit_expr(expr); - if sig_drop_finder.has_sig_drop { - cb(sdap); - if sdap.number_of_stmts > 0 { - sdap.last_use_stmt_idx = idx; - sdap.last_use_stmt_span = stmt.span; - if let hir::ExprKind::MethodCall(_, _, _, span) = expr.kind { - sdap.last_use_method_span = span; - } + self.apas.clear(); + let initial_dummy_stmt = dummy_stmt_expr(body.value); + let mut ap = AuxParams::new(&mut self.apas, &initial_dummy_stmt); + StmtsChecker::new(&mut ap, cx, &mut self.seen_types, &mut self.type_cache).visit_body(body); + for apa in ap.apas.values() { + if apa.counter <= 1 || !apa.has_expensive_expr_after_last_attr { + continue; } - sdap.number_of_stmts = sdap.number_of_stmts.wrapping_add(1); - } - } - - /// Shows generic overall messages as well as specialized messages depending on the usage. - fn set_suggestions(cx: &LateContext<'tcx>, block_span: Span, diag: &mut Diagnostic, sdap: &SigDropAuxParams) { - match sdap.number_of_stmts { - 0 | 1 => {}, - 2 => { - let indent = " ".repeat(indent_of(cx, sdap.last_use_stmt_span).unwrap_or(0)); - let init_method = snippet(cx, sdap.init_method_span, ".."); - let usage_method = snippet(cx, sdap.last_use_method_span, ".."); - let stmt = if let Some(last_use_bind_span) = sdap.last_use_bind_span { - format!( - "\n{indent}let {} = {init_method}.{usage_method};", - snippet(cx, last_use_bind_span, ".."), - ) - } else { - format!("\n{indent}{init_method}.{usage_method};") - }; - diag.span_suggestion_verbose( - sdap.init_stmt_span, - "merge the temporary construction with its single usage", - stmt, - Applicability::MaybeIncorrect, - ); - diag.span_suggestion( - sdap.last_use_stmt_span, - "remove separated single usage", - "", - Applicability::MaybeIncorrect, - ); - }, - _ => { - diag.span_suggestion( - sdap.last_use_stmt_span.shrink_to_hi(), - "drop the temporary after the end of its last usage", - format!( - "\n{}drop({});", - " ".repeat(indent_of(cx, sdap.last_use_stmt_span).unwrap_or(0)), - sdap.init_bind_ident - ), - Applicability::MaybeIncorrect, - ); - }, - } - diag.note("this might lead to unnecessary resource contention"); - diag.span_label( - block_span, - format!( - "temporary `{}` is currently being dropped at the end of its contained scope", - sdap.init_bind_ident - ), - ); - } -} - -impl<'tcx> LateLintPass<'tcx> for SignificantDropTightening<'tcx> { - fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx hir::Block<'_>) { - let dummy_ret_stmt = block.expr.map(|expr| hir::Stmt { - hir_id: hir::HirId::INVALID, - kind: hir::StmtKind::Expr(expr), - span: DUMMY_SP, - }); - let mut sdap = SigDropAuxParams::default(); - for (idx, stmt) in Self::all_block_stmts(block.stmts, dummy_ret_stmt.as_ref()).enumerate() { - match stmt.kind { - hir::StmtKind::Expr(expr) => self.modify_sdap_if_sig_drop_exists( - cx, - expr, - idx, - &mut sdap, - stmt, - |_| {} - ), - hir::StmtKind::Local(local) if let Some(expr) = local.init => self.modify_sdap_if_sig_drop_exists( - cx, - expr, - idx, - &mut sdap, - stmt, - |local_sdap| { - if local_sdap.number_of_stmts == 0 { - if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind { - local_sdap.init_bind_ident = ident; - } - if let hir::ExprKind::MethodCall(_, local_expr, _, span) = expr.kind { - local_sdap.init_method_span = local_expr.span.to(span); - } - local_sdap.init_stmt_span = stmt.span; - } - else if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind { - local_sdap.last_use_bind_span = Some(ident.span); - } - } - ), - hir::StmtKind::Semi(expr) => { - if Self::has_drop(expr, sdap.init_bind_ident) { - return; - } - self.modify_sdap_if_sig_drop_exists(cx, expr, idx, &mut sdap, stmt, |_| {}); - }, - _ => {} - }; - } - - let idx = sdap.last_use_stmt_idx.wrapping_add(1); - let stmts_after_last_use = Self::all_block_stmts(block.stmts, dummy_ret_stmt.as_ref()).skip(idx); - if sdap.number_of_stmts > 1 && Self::at_least_one_stmt_is_expensive(stmts_after_last_use) { span_lint_and_then( cx, SIGNIFICANT_DROP_TIGHTENING, - sdap.init_bind_ident.span, + apa.first_bind_ident.span, "temporary with significant `Drop` can be early dropped", |diag| { - Self::set_suggestions(cx, block.span, diag, &sdap); + match apa.counter { + 0 | 1 => {}, + 2 => { + let indent = " ".repeat(indent_of(cx, apa.last_stmt_span).unwrap_or(0)); + let init_method = snippet(cx, apa.first_method_span, ".."); + let usage_method = snippet(cx, apa.last_method_span, ".."); + let stmt = if apa.last_bind_ident == Ident::empty() { + format!("\n{indent}{init_method}.{usage_method};") + } else { + format!( + "\n{indent}let {} = {init_method}.{usage_method};", + snippet(cx, apa.last_bind_ident.span, ".."), + ) + }; + diag.span_suggestion_verbose( + apa.first_stmt_span, + "merge the temporary construction with its single usage", + stmt, + Applicability::MaybeIncorrect, + ); + diag.span_suggestion( + apa.last_stmt_span, + "remove separated single usage", + "", + Applicability::MaybeIncorrect, + ); + }, + _ => { + diag.span_suggestion( + apa.last_stmt_span.shrink_to_hi(), + "drop the temporary after the end of its last usage", + format!( + "\n{}drop({});", + " ".repeat(indent_of(cx, apa.last_stmt_span).unwrap_or(0)), + apa.first_bind_ident + ), + Applicability::MaybeIncorrect, + ); + }, + } + diag.note("this might lead to unnecessary resource contention"); + diag.span_label( + apa.first_block_span, + format!( + "temporary `{}` is currently being dropped at the end of its contained scope", + apa.first_bind_ident + ), + ); }, ); } } } -/// Auxiliary parameters used on each block check. -struct SigDropAuxParams { - /// The binding or variable that references the initial construction of the type marked with - /// `#[has_significant_drop]`. - init_bind_ident: Ident, - /// Similar to `init_bind_ident` but encompasses the right-hand method call. - init_method_span: Span, - /// Similar to `init_bind_ident` but encompasses the whole contained statement. - init_stmt_span: Span, - - /// The last visited binding or variable span within a block that had any referenced inner type - /// marked with `#[has_significant_drop]`. - last_use_bind_span: Option, - /// Index of the last visited statement within a block that had any referenced inner type - /// marked with `#[has_significant_drop]`. - last_use_stmt_idx: usize, - /// Similar to `last_use_bind_span` but encompasses the whole contained statement. - last_use_stmt_span: Span, - /// Similar to `last_use_bind_span` but encompasses the right-hand method call. - last_use_method_span: Span, - - /// Total number of statements within a block that have any referenced inner type marked with - /// `#[has_significant_drop]`. - number_of_stmts: usize, -} - -impl Default for SigDropAuxParams { - fn default() -> Self { - Self { - init_bind_ident: Ident::empty(), - init_method_span: DUMMY_SP, - init_stmt_span: DUMMY_SP, - last_use_bind_span: None, - last_use_method_span: DUMMY_SP, - last_use_stmt_idx: 0, - last_use_stmt_span: DUMMY_SP, - number_of_stmts: 0, - } - } -} - -/// Checks the existence of the `#[has_significant_drop]` attribute -struct SigDropChecker<'cx, 'sdt, 'tcx> { +/// Checks the existence of the `#[has_significant_drop]` attribute. +struct AttrChecker<'cx, 'others, 'tcx> { cx: &'cx LateContext<'tcx>, - seen_types: &'sdt mut FxHashSet>, - type_cache: &'sdt mut FxHashMap, bool>, + seen_types: &'others mut FxHashSet>, + type_cache: &'others mut FxHashMap, bool>, } -impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> { +impl<'cx, 'others, 'tcx> AttrChecker<'cx, 'others, 'tcx> { pub(crate) fn new( cx: &'cx LateContext<'tcx>, - seen_types: &'sdt mut FxHashSet>, - type_cache: &'sdt mut FxHashMap, bool>, + seen_types: &'others mut FxHashSet>, + type_cache: &'others mut FxHashMap, bool>, ) -> Self { seen_types.clear(); Self { @@ -314,7 +162,17 @@ impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> { } } - pub(crate) fn has_sig_drop_attr_uncached(&mut self, ty: Ty<'tcx>) -> bool { + fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool { + // The borrow checker prevents us from using something fancier like or_insert_with. + if let Some(ty) = self.type_cache.get(&ty) { + return *ty; + } + let value = self.has_sig_drop_attr_uncached(ty); + self.type_cache.insert(ty, value); + value + } + + fn has_sig_drop_attr_uncached(&mut self, ty: Ty<'tcx>) -> bool { if let Some(adt) = ty.ty_adt_def() { let mut iter = get_attr( self.cx.sess(), @@ -350,73 +208,244 @@ impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> { } } - pub(crate) fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool { - // The borrow checker prevents us from using something fancier like or_insert_with. - if let Some(ty) = self.type_cache.get(&ty) { - return *ty; - } - let value = self.has_sig_drop_attr_uncached(ty); - self.type_cache.insert(ty, value); - value - } - fn has_seen_ty(&mut self, ty: Ty<'tcx>) -> bool { !self.seen_types.insert(ty) } } -/// Performs recursive calls to find any inner type marked with `#[has_significant_drop]`. -struct SigDropFinder<'cx, 'sdt, 'tcx> { - cx: &'cx LateContext<'tcx>, - has_sig_drop: bool, - sig_drop_checker: SigDropChecker<'cx, 'sdt, 'tcx>, +struct StmtsChecker<'ap, 'lc, 'others, 'stmt, 'tcx> { + ap: &'ap mut AuxParams<'others, 'stmt, 'tcx>, + cx: &'lc LateContext<'tcx>, + seen_types: &'others mut FxHashSet>, + type_cache: &'others mut FxHashMap, bool>, } -impl<'cx, 'sdt, 'tcx> SigDropFinder<'cx, 'sdt, 'tcx> { +impl<'ap, 'lc, 'others, 'stmt, 'tcx> StmtsChecker<'ap, 'lc, 'others, 'stmt, 'tcx> { fn new( - cx: &'cx LateContext<'tcx>, - seen_types: &'sdt mut FxHashSet>, - type_cache: &'sdt mut FxHashMap, bool>, + ap: &'ap mut AuxParams<'others, 'stmt, 'tcx>, + cx: &'lc LateContext<'tcx>, + seen_types: &'others mut FxHashSet>, + type_cache: &'others mut FxHashMap, bool>, ) -> Self { Self { + ap, cx, - has_sig_drop: false, - sig_drop_checker: SigDropChecker::new(cx, seen_types, type_cache), + seen_types, + type_cache, + } + } + + fn manage_has_expensive_expr_after_last_attr(&mut self) { + let has_expensive_stmt = match self.ap.curr_stmt.kind { + hir::StmtKind::Expr(expr) if !is_expensive_expr(expr) => false, + hir::StmtKind::Local(local) if let Some(expr) = local.init + && let hir::ExprKind::Path(_) = expr.kind => false, + _ => true + }; + if has_expensive_stmt { + for apa in self.ap.apas.values_mut() { + let last_stmt_is_not_dummy = apa.last_stmt_span != DUMMY_SP; + let last_stmt_is_not_curr = self.ap.curr_stmt.span != apa.last_stmt_span; + let block_equals_curr = self.ap.curr_block_hir_id == apa.first_block_hir_id; + let block_is_ancestor = self + .cx + .tcx + .hir() + .parent_iter(self.ap.curr_block_hir_id) + .any(|(id, _)| id == apa.first_block_hir_id); + if last_stmt_is_not_dummy && last_stmt_is_not_curr && (block_equals_curr || block_is_ancestor) { + apa.has_expensive_expr_after_last_attr = true; + } + } } } } -impl<'cx, 'sdt, 'tcx> Visitor<'tcx> for SigDropFinder<'cx, 'sdt, 'tcx> { - fn visit_expr(&mut self, ex: &'tcx hir::Expr<'_>) { - if self - .sig_drop_checker - .has_sig_drop_attr(self.cx.typeck_results().expr_ty(ex)) - { - self.has_sig_drop = true; - return; +impl<'ap, 'lc, 'others, 'stmt, 'tcx> Visitor<'tcx> for StmtsChecker<'ap, 'lc, 'others, 'stmt, 'tcx> { + fn visit_block(&mut self, block: &'tcx hir::Block<'tcx>) { + self.ap.curr_block_hir_id = block.hir_id; + self.ap.curr_block_span = block.span; + for stmt in block.stmts { + self.ap.curr_stmt = Cow::Borrowed(stmt); + self.visit_stmt(stmt); + self.ap.curr_block_hir_id = block.hir_id; + self.ap.curr_block_span = block.span; + self.manage_has_expensive_expr_after_last_attr(); + } + if let Some(expr) = block.expr { + self.ap.curr_stmt = Cow::Owned(dummy_stmt_expr(expr)); + self.visit_expr(expr); + self.ap.curr_block_hir_id = block.hir_id; + self.ap.curr_block_span = block.span; + self.manage_has_expensive_expr_after_last_attr(); } + } - match ex.kind { - hir::ExprKind::MethodCall(_, expr, ..) => { - self.visit_expr(expr); - }, - hir::ExprKind::Array(..) - | hir::ExprKind::Assign(..) - | hir::ExprKind::AssignOp(..) - | hir::ExprKind::Binary(..) - | hir::ExprKind::Call(..) - | hir::ExprKind::Field(..) - | hir::ExprKind::If(..) - | hir::ExprKind::Index(..) - | hir::ExprKind::Match(..) - | hir::ExprKind::Repeat(..) - | hir::ExprKind::Ret(..) - | hir::ExprKind::Tup(..) - | hir::ExprKind::Unary(..) - | hir::ExprKind::Yield(..) => { - walk_expr(self, ex); - }, - _ => {}, + fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { + let modify_apa_params = |apa: &mut AuxParamsAttr| { + apa.counter = apa.counter.wrapping_add(1); + apa.has_expensive_expr_after_last_attr = false; + }; + let mut ac = AttrChecker::new(self.cx, self.seen_types, self.type_cache); + if ac.has_sig_drop_attr(self.cx.typeck_results().expr_ty(expr)) { + if let hir::StmtKind::Local(local) = self.ap.curr_stmt.kind + && let hir::PatKind::Binding(_, hir_id, ident, _) = local.pat.kind + && !self.ap.apas.contains_key(&hir_id) + && { + if let Some(local_hir_id) = path_to_local(expr) { + local_hir_id == hir_id + } + else { + true + } + } + { + let mut apa = AuxParamsAttr { + first_bind_ident: ident, + first_block_hir_id: self.ap.curr_block_hir_id, + first_block_span: self.ap.curr_block_span, + first_method_span: { + let expr_or_init = expr_or_init(self.cx, expr); + if let hir::ExprKind::MethodCall(_, local_expr, _, span) = expr_or_init.kind { + local_expr.span.to(span) + } + else { + expr_or_init.span + } + }, + first_stmt_span: self.ap.curr_stmt.span, + ..Default::default() + }; + modify_apa_params(&mut apa); + let _ = self.ap.apas.insert(hir_id, apa); + } else { + let Some(hir_id) = path_to_local(expr) else { return; }; + let Some(apa) = self.ap.apas.get_mut(&hir_id) else { return; }; + match self.ap.curr_stmt.kind { + hir::StmtKind::Local(local) => { + if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind { + apa.last_bind_ident = ident; + } + if let Some(local_init) = local.init + && let hir::ExprKind::MethodCall(_, _, _, span) = local_init.kind + { + apa.last_method_span = span; + } + }, + hir::StmtKind::Semi(expr) => { + if has_drop(expr, &apa.first_bind_ident) { + apa.has_expensive_expr_after_last_attr = false; + apa.last_stmt_span = DUMMY_SP; + return; + } + if let hir::ExprKind::MethodCall(_, _, _, span) = expr.kind { + apa.last_method_span = span; + } + }, + _ => {}, + } + apa.last_stmt_span = self.ap.curr_stmt.span; + modify_apa_params(apa); + } + } + walk_expr(self, expr); + } +} + +/// Auxiliary parameters used on each block check of an item +struct AuxParams<'others, 'stmt, 'tcx> { + //// See [AuxParamsAttr]. + apas: &'others mut FxIndexMap, + /// The current block identifier that is being visited. + curr_block_hir_id: hir::HirId, + /// The current block span that is being visited. + curr_block_span: Span, + /// The current statement that is being visited. + curr_stmt: Cow<'stmt, hir::Stmt<'tcx>>, +} + +impl<'others, 'stmt, 'tcx> AuxParams<'others, 'stmt, 'tcx> { + fn new(apas: &'others mut FxIndexMap, curr_stmt: &'stmt hir::Stmt<'tcx>) -> Self { + Self { + apas, + curr_block_hir_id: hir::HirId::INVALID, + curr_block_span: DUMMY_SP, + curr_stmt: Cow::Borrowed(curr_stmt), + } + } +} + +/// Auxiliary parameters used on expression created with `#[has_significant_drop]`. +#[derive(Debug)] +struct AuxParamsAttr { + /// The number of times `#[has_significant_drop]` was referenced. + counter: usize, + /// If an expensive expression follows the last use of anything marked with + /// `#[has_significant_drop]`. + has_expensive_expr_after_last_attr: bool, + + /// The identifier of the block that involves the first `#[has_significant_drop]`. + first_block_hir_id: hir::HirId, + /// The span of the block that involves the first `#[has_significant_drop]`. + first_block_span: Span, + /// The binding or variable that references the initial construction of the type marked with + /// `#[has_significant_drop]`. + first_bind_ident: Ident, + /// Similar to `init_bind_ident` but encompasses the right-hand method call. + first_method_span: Span, + /// Similar to `init_bind_ident` but encompasses the whole contained statement. + first_stmt_span: Span, + + /// The last visited binding or variable span within a block that had any referenced inner type + /// marked with `#[has_significant_drop]`. + last_bind_ident: Ident, + /// Similar to `last_bind_span` but encompasses the right-hand method call. + last_method_span: Span, + /// Similar to `last_bind_span` but encompasses the whole contained statement. + last_stmt_span: Span, +} + +impl Default for AuxParamsAttr { + fn default() -> Self { + Self { + counter: 0, + has_expensive_expr_after_last_attr: false, + first_block_hir_id: hir::HirId::INVALID, + first_bind_ident: Ident::empty(), + first_block_span: DUMMY_SP, + first_method_span: DUMMY_SP, + first_stmt_span: DUMMY_SP, + last_bind_ident: Ident::empty(), + last_method_span: DUMMY_SP, + last_stmt_span: DUMMY_SP, } } } + +fn dummy_stmt_expr<'any>(expr: &'any hir::Expr<'any>) -> hir::Stmt<'any> { + hir::Stmt { + hir_id: hir::HirId::INVALID, + kind: hir::StmtKind::Expr(expr), + span: DUMMY_SP, + } +} + +fn has_drop(expr: &hir::Expr<'_>, first_bind_ident: &Ident) -> bool { + if let hir::ExprKind::Call(fun, args) = expr.kind + && let hir::ExprKind::Path(hir::QPath::Resolved(_, fun_path)) = &fun.kind + && let [fun_ident, ..] = fun_path.segments + && fun_ident.ident.name == rustc_span::sym::drop + && let [first_arg, ..] = args + && let hir::ExprKind::Path(hir::QPath::Resolved(_, arg_path)) = &first_arg.kind + && let [first_arg_ps, .. ] = arg_path.segments + { + &first_arg_ps.ident == first_bind_ident + } + else { + false + } +} + +fn is_expensive_expr(expr: &hir::Expr<'_>) -> bool { + !matches!(expr.kind, hir::ExprKind::Path(_)) +} diff --git a/tests/ui/significant_drop_tightening.fixed b/tests/ui/significant_drop_tightening.fixed index ee7f2b0631ad6..7b848ead78467 100644 --- a/tests/ui/significant_drop_tightening.fixed +++ b/tests/ui/significant_drop_tightening.fixed @@ -16,6 +16,18 @@ pub fn complex_return_triggers_the_lint() -> i32 { foo() } +pub fn issue_10413() { + let mutex = Mutex::new(Some(1)); + let opt = Some(1); + if opt.is_some() { + let lock = mutex.lock().unwrap(); + let _ = *lock; + if opt.is_some() { + let _ = *lock; + } + } +} + pub fn path_return_can_be_ignored() -> i32 { let mutex = Mutex::new(1); let lock = mutex.lock().unwrap(); diff --git a/tests/ui/significant_drop_tightening.rs b/tests/ui/significant_drop_tightening.rs index 9c139deb95f2d..36f77cf1bdb6e 100644 --- a/tests/ui/significant_drop_tightening.rs +++ b/tests/ui/significant_drop_tightening.rs @@ -15,6 +15,18 @@ pub fn complex_return_triggers_the_lint() -> i32 { foo() } +pub fn issue_10413() { + let mutex = Mutex::new(Some(1)); + let opt = Some(1); + if opt.is_some() { + let lock = mutex.lock().unwrap(); + let _ = *lock; + if opt.is_some() { + let _ = *lock; + } + } +} + pub fn path_return_can_be_ignored() -> i32 { let mutex = Mutex::new(1); let lock = mutex.lock().unwrap(); diff --git a/tests/ui/significant_drop_tightening.stderr b/tests/ui/significant_drop_tightening.stderr index ab8ce356ec7b5..3bdac0b0a6b7b 100644 --- a/tests/ui/significant_drop_tightening.stderr +++ b/tests/ui/significant_drop_tightening.stderr @@ -23,7 +23,7 @@ LL + drop(lock); | error: temporary with significant `Drop` can be early dropped - --> $DIR/significant_drop_tightening.rs:44:13 + --> $DIR/significant_drop_tightening.rs:56:13 | LL | / { LL | | let mutex = Mutex::new(1i32); @@ -43,7 +43,7 @@ LL + drop(lock); | error: temporary with significant `Drop` can be early dropped - --> $DIR/significant_drop_tightening.rs:65:13 + --> $DIR/significant_drop_tightening.rs:77:13 | LL | / { LL | | let mutex = Mutex::new(1i32); @@ -67,7 +67,7 @@ LL + | error: temporary with significant `Drop` can be early dropped - --> $DIR/significant_drop_tightening.rs:71:17 + --> $DIR/significant_drop_tightening.rs:83:17 | LL | / { LL | | let mutex = Mutex::new(vec![1i32]);