mirror of https://github.com/rust-lang/rust.git
Fix #10413
This commit is contained in:
Caio
parent
9020937bbe
commit
f0619024b8
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@ -1,10 +1,10 @@
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use clippy_utils::{
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diagnostics::span_lint_and_then,
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get_attr,
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expr_or_init, get_attr, path_to_local,
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source::{indent_of, snippet},
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};
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_errors::{Applicability, Diagnostic};
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use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
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use rustc_errors::Applicability;
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use rustc_hir::{
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self as hir,
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intravisit::{walk_expr, Visitor},
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@ -13,6 +13,7 @@ use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::ty::{subst::GenericArgKind, Ty, TypeAndMut};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::{symbol::Ident, Span, DUMMY_SP};
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use std::borrow::Cow;
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declare_clippy_lint! {
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/// ### What it does
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@ -56,255 +57,102 @@ impl_lint_pass!(SignificantDropTightening<'_> => [SIGNIFICANT_DROP_TIGHTENING]);
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#[derive(Default)]
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pub struct SignificantDropTightening<'tcx> {
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apas: FxIndexMap<hir::HirId, AuxParamsAttr>,
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/// Auxiliary structure used to avoid having to verify the same type multiple times.
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seen_types: FxHashSet<Ty<'tcx>>,
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type_cache: FxHashMap<Ty<'tcx>, bool>,
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}
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impl<'tcx> SignificantDropTightening<'tcx> {
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/// Unifies the statements of a block with its return expression.
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fn all_block_stmts<'ret, 'rslt, 'stmts>(
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block_stmts: &'stmts [hir::Stmt<'tcx>],
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dummy_ret_stmt: Option<&'ret hir::Stmt<'tcx>>,
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) -> impl Iterator<Item = &'rslt hir::Stmt<'tcx>>
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where
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'ret: 'rslt,
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'stmts: 'rslt,
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{
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block_stmts.iter().chain(dummy_ret_stmt)
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}
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/// Searches for at least one statement that could slow down the release of a significant drop.
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fn at_least_one_stmt_is_expensive<'stmt>(stmts: impl Iterator<Item = &'stmt hir::Stmt<'tcx>>) -> bool
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where
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'tcx: 'stmt,
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{
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for stmt in stmts {
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match stmt.kind {
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hir::StmtKind::Expr(expr) if let hir::ExprKind::Path(_) = expr.kind => {}
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hir::StmtKind::Local(local) if let Some(expr) = local.init
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&& let hir::ExprKind::Path(_) = expr.kind => {},
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_ => return true
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};
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}
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false
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}
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/// Verifies if the expression is of type `drop(some_lock_path)` to assert that the temporary
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/// is already being dropped before the end of its scope.
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fn has_drop(expr: &'tcx hir::Expr<'_>, init_bind_ident: Ident) -> bool {
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if let hir::ExprKind::Call(fun, args) = expr.kind
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&& let hir::ExprKind::Path(hir::QPath::Resolved(_, fun_path)) = &fun.kind
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&& let [fun_ident, ..] = fun_path.segments
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&& fun_ident.ident.name == rustc_span::sym::drop
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&& let [first_arg, ..] = args
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&& let hir::ExprKind::Path(hir::QPath::Resolved(_, arg_path)) = &first_arg.kind
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&& let [first_arg_ps, .. ] = arg_path.segments
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{
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first_arg_ps.ident == init_bind_ident
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}
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else {
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false
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}
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}
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/// Tries to find types marked with `#[has_significant_drop]` of an expression `expr` that is
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/// originated from `stmt` and then performs common logic on `sdap`.
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fn modify_sdap_if_sig_drop_exists(
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impl<'tcx> LateLintPass<'tcx> for SignificantDropTightening<'tcx> {
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fn check_fn(
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&mut self,
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cx: &LateContext<'tcx>,
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expr: &'tcx hir::Expr<'_>,
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idx: usize,
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sdap: &mut SigDropAuxParams,
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stmt: &hir::Stmt<'_>,
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cb: impl Fn(&mut SigDropAuxParams),
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_: hir::intravisit::FnKind<'_>,
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_: &hir::FnDecl<'_>,
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body: &'tcx hir::Body<'_>,
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_: Span,
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_: hir::def_id::LocalDefId,
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) {
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let mut sig_drop_finder = SigDropFinder::new(cx, &mut self.seen_types, &mut self.type_cache);
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sig_drop_finder.visit_expr(expr);
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if sig_drop_finder.has_sig_drop {
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cb(sdap);
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if sdap.number_of_stmts > 0 {
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sdap.last_use_stmt_idx = idx;
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sdap.last_use_stmt_span = stmt.span;
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if let hir::ExprKind::MethodCall(_, _, _, span) = expr.kind {
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sdap.last_use_method_span = span;
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}
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self.apas.clear();
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let initial_dummy_stmt = dummy_stmt_expr(&body.value);
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let mut ap = AuxParams::new(&mut self.apas, &initial_dummy_stmt);
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StmtsChecker::new(&mut ap, cx, &mut self.seen_types, &mut self.type_cache).visit_body(body);
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for apa in ap.apas.values() {
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if apa.counter <= 1 || !apa.has_expensive_expr_after_last_attr {
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continue;
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}
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sdap.number_of_stmts = sdap.number_of_stmts.wrapping_add(1);
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}
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}
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/// Shows generic overall messages as well as specialized messages depending on the usage.
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fn set_suggestions(cx: &LateContext<'tcx>, block_span: Span, diag: &mut Diagnostic, sdap: &SigDropAuxParams) {
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match sdap.number_of_stmts {
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0 | 1 => {},
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2 => {
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let indent = " ".repeat(indent_of(cx, sdap.last_use_stmt_span).unwrap_or(0));
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let init_method = snippet(cx, sdap.init_method_span, "..");
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let usage_method = snippet(cx, sdap.last_use_method_span, "..");
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let stmt = if let Some(last_use_bind_span) = sdap.last_use_bind_span {
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format!(
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"\n{indent}let {} = {init_method}.{usage_method};",
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snippet(cx, last_use_bind_span, ".."),
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)
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} else {
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format!("\n{indent}{init_method}.{usage_method};")
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};
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diag.span_suggestion_verbose(
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sdap.init_stmt_span,
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"merge the temporary construction with its single usage",
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stmt,
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Applicability::MaybeIncorrect,
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);
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diag.span_suggestion(
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sdap.last_use_stmt_span,
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"remove separated single usage",
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"",
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Applicability::MaybeIncorrect,
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);
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},
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_ => {
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diag.span_suggestion(
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sdap.last_use_stmt_span.shrink_to_hi(),
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"drop the temporary after the end of its last usage",
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format!(
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"\n{}drop({});",
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" ".repeat(indent_of(cx, sdap.last_use_stmt_span).unwrap_or(0)),
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sdap.init_bind_ident
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),
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Applicability::MaybeIncorrect,
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);
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},
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}
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diag.note("this might lead to unnecessary resource contention");
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diag.span_label(
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block_span,
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format!(
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"temporary `{}` is currently being dropped at the end of its contained scope",
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sdap.init_bind_ident
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),
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);
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}
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}
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impl<'tcx> LateLintPass<'tcx> for SignificantDropTightening<'tcx> {
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fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx hir::Block<'_>) {
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let dummy_ret_stmt = block.expr.map(|expr| hir::Stmt {
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hir_id: hir::HirId::INVALID,
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kind: hir::StmtKind::Expr(expr),
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span: DUMMY_SP,
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});
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let mut sdap = SigDropAuxParams::default();
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for (idx, stmt) in Self::all_block_stmts(block.stmts, dummy_ret_stmt.as_ref()).enumerate() {
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match stmt.kind {
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hir::StmtKind::Expr(expr) => self.modify_sdap_if_sig_drop_exists(
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cx,
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expr,
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idx,
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&mut sdap,
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stmt,
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|_| {}
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),
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hir::StmtKind::Local(local) if let Some(expr) = local.init => self.modify_sdap_if_sig_drop_exists(
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cx,
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expr,
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idx,
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&mut sdap,
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stmt,
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|local_sdap| {
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if local_sdap.number_of_stmts == 0 {
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if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind {
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local_sdap.init_bind_ident = ident;
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}
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if let hir::ExprKind::MethodCall(_, local_expr, _, span) = expr.kind {
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local_sdap.init_method_span = local_expr.span.to(span);
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}
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local_sdap.init_stmt_span = stmt.span;
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}
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else if let hir::PatKind::Binding(_, _, ident, _) = local.pat.kind {
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local_sdap.last_use_bind_span = Some(ident.span);
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}
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}
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),
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hir::StmtKind::Semi(expr) => {
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if Self::has_drop(expr, sdap.init_bind_ident) {
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return;
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}
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self.modify_sdap_if_sig_drop_exists(cx, expr, idx, &mut sdap, stmt, |_| {});
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},
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_ => {}
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};
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}
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let idx = sdap.last_use_stmt_idx.wrapping_add(1);
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let stmts_after_last_use = Self::all_block_stmts(block.stmts, dummy_ret_stmt.as_ref()).skip(idx);
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if sdap.number_of_stmts > 1 && Self::at_least_one_stmt_is_expensive(stmts_after_last_use) {
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span_lint_and_then(
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cx,
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SIGNIFICANT_DROP_TIGHTENING,
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sdap.init_bind_ident.span,
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apa.first_bind_ident.span,
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"temporary with significant `Drop` can be early dropped",
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|diag| {
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Self::set_suggestions(cx, block.span, diag, &sdap);
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match apa.counter {
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0 | 1 => {},
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2 => {
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let indent = " ".repeat(indent_of(cx, apa.last_stmt_span).unwrap_or(0));
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let init_method = snippet(cx, apa.first_method_span, "..");
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let usage_method = snippet(cx, apa.last_method_span, "..");
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let stmt = if apa.last_bind_ident != Ident::empty() {
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format!(
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"\n{indent}let {} = {init_method}.{usage_method};",
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snippet(cx, apa.last_bind_ident.span, ".."),
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)
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} else {
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format!("\n{indent}{init_method}.{usage_method};")
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};
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diag.span_suggestion_verbose(
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apa.first_stmt_span,
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"merge the temporary construction with its single usage",
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stmt,
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Applicability::MaybeIncorrect,
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);
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diag.span_suggestion(
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apa.last_stmt_span,
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"remove separated single usage",
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"",
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Applicability::MaybeIncorrect,
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);
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},
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_ => {
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diag.span_suggestion(
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apa.last_stmt_span.shrink_to_hi(),
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"drop the temporary after the end of its last usage",
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format!(
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"\n{}drop({});",
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" ".repeat(indent_of(cx, apa.last_stmt_span).unwrap_or(0)),
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apa.first_bind_ident
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),
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Applicability::MaybeIncorrect,
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);
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},
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}
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diag.note("this might lead to unnecessary resource contention");
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diag.span_label(
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apa.first_block_span,
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format!(
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"temporary `{}` is currently being dropped at the end of its contained scope",
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apa.first_bind_ident
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),
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);
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},
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);
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}
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}
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}
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/// Auxiliary parameters used on each block check.
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struct SigDropAuxParams {
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/// The binding or variable that references the initial construction of the type marked with
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/// `#[has_significant_drop]`.
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init_bind_ident: Ident,
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/// Similar to `init_bind_ident` but encompasses the right-hand method call.
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init_method_span: Span,
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/// Similar to `init_bind_ident` but encompasses the whole contained statement.
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init_stmt_span: Span,
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/// The last visited binding or variable span within a block that had any referenced inner type
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/// marked with `#[has_significant_drop]`.
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last_use_bind_span: Option<Span>,
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/// Index of the last visited statement within a block that had any referenced inner type
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/// marked with `#[has_significant_drop]`.
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last_use_stmt_idx: usize,
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/// Similar to `last_use_bind_span` but encompasses the whole contained statement.
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last_use_stmt_span: Span,
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/// Similar to `last_use_bind_span` but encompasses the right-hand method call.
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last_use_method_span: Span,
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/// Total number of statements within a block that have any referenced inner type marked with
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/// `#[has_significant_drop]`.
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number_of_stmts: usize,
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}
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impl Default for SigDropAuxParams {
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fn default() -> Self {
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Self {
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init_bind_ident: Ident::empty(),
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init_method_span: DUMMY_SP,
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init_stmt_span: DUMMY_SP,
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last_use_bind_span: None,
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last_use_method_span: DUMMY_SP,
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last_use_stmt_idx: 0,
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last_use_stmt_span: DUMMY_SP,
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number_of_stmts: 0,
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}
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}
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}
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/// Checks the existence of the `#[has_significant_drop]` attribute
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struct SigDropChecker<'cx, 'sdt, 'tcx> {
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/// Checks the existence of the `#[has_significant_drop]` attribute.
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struct AttrChecker<'cx, 'others, 'tcx> {
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cx: &'cx LateContext<'tcx>,
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seen_types: &'sdt mut FxHashSet<Ty<'tcx>>,
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type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>,
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seen_types: &'others mut FxHashSet<Ty<'tcx>>,
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type_cache: &'others mut FxHashMap<Ty<'tcx>, bool>,
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}
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impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> {
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impl<'cx, 'others, 'tcx> AttrChecker<'cx, 'others, 'tcx> {
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pub(crate) fn new(
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cx: &'cx LateContext<'tcx>,
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seen_types: &'sdt mut FxHashSet<Ty<'tcx>>,
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type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>,
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seen_types: &'others mut FxHashSet<Ty<'tcx>>,
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type_cache: &'others mut FxHashMap<Ty<'tcx>, bool>,
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) -> Self {
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seen_types.clear();
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Self {
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@ -314,7 +162,17 @@ impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> {
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}
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}
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pub(crate) fn has_sig_drop_attr_uncached(&mut self, ty: Ty<'tcx>) -> bool {
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fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool {
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// The borrow checker prevents us from using something fancier like or_insert_with.
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if let Some(ty) = self.type_cache.get(&ty) {
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return *ty;
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}
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let value = self.has_sig_drop_attr_uncached(ty);
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self.type_cache.insert(ty, value);
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value
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}
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fn has_sig_drop_attr_uncached(&mut self, ty: Ty<'tcx>) -> bool {
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if let Some(adt) = ty.ty_adt_def() {
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let mut iter = get_attr(
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self.cx.sess(),
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@ -350,73 +208,246 @@ impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> {
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}
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}
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pub(crate) fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool {
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// The borrow checker prevents us from using something fancier like or_insert_with.
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if let Some(ty) = self.type_cache.get(&ty) {
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return *ty;
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}
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let value = self.has_sig_drop_attr_uncached(ty);
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self.type_cache.insert(ty, value);
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value
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}
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fn has_seen_ty(&mut self, ty: Ty<'tcx>) -> bool {
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!self.seen_types.insert(ty)
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}
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}
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/// Performs recursive calls to find any inner type marked with `#[has_significant_drop]`.
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struct SigDropFinder<'cx, 'sdt, 'tcx> {
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cx: &'cx LateContext<'tcx>,
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has_sig_drop: bool,
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sig_drop_checker: SigDropChecker<'cx, 'sdt, 'tcx>,
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struct StmtsChecker<'ap, 'lc, 'others, 'stmt, 'tcx> {
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ap: &'ap mut AuxParams<'others, 'stmt, 'tcx>,
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cx: &'lc LateContext<'tcx>,
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seen_types: &'others mut FxHashSet<Ty<'tcx>>,
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type_cache: &'others mut FxHashMap<Ty<'tcx>, bool>,
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}
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impl<'cx, 'sdt, 'tcx> SigDropFinder<'cx, 'sdt, 'tcx> {
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impl<'ap, 'lc, 'others, 'stmt, 'tcx> StmtsChecker<'ap, 'lc, 'others, 'stmt, 'tcx> {
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fn new(
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cx: &'cx LateContext<'tcx>,
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seen_types: &'sdt mut FxHashSet<Ty<'tcx>>,
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type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>,
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ap: &'ap mut AuxParams<'others, 'stmt, 'tcx>,
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cx: &'lc LateContext<'tcx>,
|
||||
seen_types: &'others mut FxHashSet<Ty<'tcx>>,
|
||||
type_cache: &'others mut FxHashMap<Ty<'tcx>, 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.iter() {
|
||||
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::default();
|
||||
apa.first_bind_ident = ident;
|
||||
apa.first_block_hir_id = self.ap.curr_block_hir_id;
|
||||
apa.first_block_span = self.ap.curr_block_span;
|
||||
apa.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
|
||||
}
|
||||
};
|
||||
apa.first_stmt_span = self.ap.curr_stmt.span;
|
||||
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<hir::HirId, AuxParamsAttr>,
|
||||
/// 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<hir::HirId, AuxParamsAttr>, 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 {
|
||||
if let hir::ExprKind::Path(_) = expr.kind {
|
||||
false
|
||||
} else {
|
||||
true
|
||||
}
|
||||
}
|
||||
|
|
|
|||
|
|
@ -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();
|
||||
|
|
|
|||
|
|
@ -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();
|
||||
|
|
|
|||
|
|
@ -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]);
|
||||
|
|
|
|||
Loading…
Reference in New Issue