Auto merge of #8856 - xFrednet:rustup, r=Manishearth,Alexendoo

Rustup

`@rust-lang/clippy,` `@Jarcho,` `@dswij,` `@Alexendoo.` Could someone review this? It should be pretty straight forward since it's just a sync. I think it's also fine if either one of `@Jarcho,` `@dswij,` `@Alexendoo` approves this, as these are usually not reviewed. I just want to make sure that I didn't break something obvious 🙃

It should be enough to look at the merge commit 🙃

changelog: none
changelog: move [`significant_drop_in_scrutinee`] to `suspicious`

CHANGELOG.md

@@ -3715,6 +3715,7 @@ Released 2018-09-13
 [`short_circuit_statement`]: https://rust-lang.github.io/rust-clippy/master/index.html#short_circuit_statement
 [`should_assert_eq`]: https://rust-lang.github.io/rust-clippy/master/index.html#should_assert_eq
 [`should_implement_trait`]: https://rust-lang.github.io/rust-clippy/master/index.html#should_implement_trait
+[`significant_drop_in_scrutinee`]: https://rust-lang.github.io/rust-clippy/master/index.html#significant_drop_in_scrutinee
 [`similar_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#similar_names
 [`single_char_add_str`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_char_add_str
 [`single_char_lifetime_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_char_lifetime_names

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "clippy"
-version = "0.1.62"
+version = "0.1.63"
 description = "A bunch of helpful lints to avoid common pitfalls in Rust"
 repository = "https://github.com/rust-lang/rust-clippy"
 readme = "README.md"

clippy_lints/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "clippy_lints"
-version = "0.1.62"
+version = "0.1.63"
 description = "A bunch of helpful lints to avoid common pitfalls in Rust"
 repository = "https://github.com/rust-lang/rust-clippy"
 readme = "README.md"

clippy_lints/src/collapsible_match.rs

@@ -5,7 +5,7 @@ use clippy_utils::{is_lang_ctor, is_unit_expr, path_to_local, peel_blocks_with_s
 use if_chain::if_chain;
 use rustc_errors::MultiSpan;
 use rustc_hir::LangItem::OptionNone;
-use rustc_hir::{Arm, Expr, Guard, HirId, Pat, PatKind};
+use rustc_hir::{Arm, Expr, Guard, HirId, Let, Pat, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;
@@ -109,7 +109,10 @@ fn check_arm<'tcx>(
             (Some(a), Some(b)) => SpanlessEq::new(cx).eq_expr(a, b),
         };
         // the binding must not be used in the if guard
-        if outer_guard.map_or(true, |(Guard::If(e) | Guard::IfLet(_, e))| !is_local_used(cx, *e, binding_id));
+        if outer_guard.map_or(
+            true,
+            |(Guard::If(e) | Guard::IfLet(Let { init: e, .. }))| !is_local_used(cx, *e, binding_id)
+        );
         // ...or anywhere in the inner expression
         if match inner {
             IfLetOrMatch::IfLet(_, _, body, els) => {

clippy_lints/src/derivable_impls.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::{is_automatically_derived, is_default_equivalent, peel_blocks};
+use clippy_utils::{is_default_equivalent, peel_blocks};
 use rustc_hir::{
     def::{DefKind, Res},
     Body, Expr, ExprKind, GenericArg, Impl, ImplItemKind, Item, ItemKind, Node, PathSegment, QPath, TyKind,
@@ -71,8 +71,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
                 self_ty,
                 ..
             }) = item.kind;
-            if let attrs = cx.tcx.hir().attrs(item.hir_id());
+            if !cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
-            if !is_automatically_derived(attrs);
             if !item.span.from_expansion();
             if let Some(def_id) = trait_ref.trait_def_id();
             if cx.tcx.is_diagnostic_item(sym::Default, def_id);
@@ -81,6 +80,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
             if let ImplItemKind::Fn(_, b) = &impl_item.kind;
             if let Body { value: func_expr, .. } = cx.tcx.hir().body(*b);
             if let Some(adt_def) = cx.tcx.type_of(item.def_id).ty_adt_def();
+            if let attrs = cx.tcx.hir().attrs(item.hir_id());
             if !attrs.iter().any(|attr| attr.doc_str().is_some());
             if let child_attrs = cx.tcx.hir().attrs(impl_item_hir);
             if !child_attrs.iter().any(|attr| attr.doc_str().is_some());

clippy_lints/src/derive.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::paths;
 use clippy_utils::ty::{implements_trait, is_copy};
-use clippy_utils::{is_automatically_derived, is_lint_allowed, match_def_path};
+use clippy_utils::{is_lint_allowed, match_def_path};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
@@ -205,8 +205,7 @@ impl<'tcx> LateLintPass<'tcx> for Derive {
         }) = item.kind
         {
             let ty = cx.tcx.type_of(item.def_id);
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
+            let is_automatically_derived = cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
-            let is_automatically_derived = is_automatically_derived(attrs);
 
             check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
             check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
@@ -236,7 +235,7 @@ fn check_hash_peq<'tcx>(
         then {
             // Look for the PartialEq implementations for `ty`
             cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
-                let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
+                let peq_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
 
                 if peq_is_automatically_derived == hash_is_automatically_derived {
                     return;
@@ -290,7 +289,7 @@ fn check_ord_partial_ord<'tcx>(
         then {
             // Look for the PartialOrd implementations for `ty`
             cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
-                let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
+                let partial_ord_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
 
                 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
                     return;

clippy_lints/src/entry.rs

@@ -11,7 +11,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{
     hir_id::HirIdSet,
     intravisit::{walk_expr, Visitor},
-    Block, Expr, ExprKind, Guard, HirId, Pat, Stmt, StmtKind, UnOp,
+    Block, Expr, ExprKind, Guard, HirId, Let, Pat, Stmt, StmtKind, UnOp,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -478,7 +478,7 @@ impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
                     let mut is_map_used = self.is_map_used;
                     for arm in arms {
                         self.visit_pat(arm.pat);
-                        if let Some(Guard::If(guard) | Guard::IfLet(_, guard)) = arm.guard {
+                        if let Some(Guard::If(guard) | Guard::IfLet(&Let { init: guard, .. })) = arm.guard {
                             self.visit_non_tail_expr(guard);
                         }
                         is_map_used |= self.visit_cond_arm(arm.body);

clippy_lints/src/eta_reduction.rs

@@ -150,7 +150,7 @@ impl<'tcx> LateLintPass<'tcx> for EtaReduction {
             if check_inputs(cx, body.params, args);
             let method_def_id = cx.typeck_results().type_dependent_def_id(body.value.hir_id).unwrap();
             let substs = cx.typeck_results().node_substs(body.value.hir_id);
-            let call_ty = cx.tcx.type_of(method_def_id).subst(cx.tcx, substs);
+            let call_ty = cx.tcx.bound_type_of(method_def_id).subst(cx.tcx, substs);
             if check_sig(cx, closure_ty, call_ty);
             then {
                 span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure", |diag| {

clippy_lints/src/functions/must_use.rs

@@ -13,13 +13,13 @@ use clippy_utils::attrs::is_proc_macro;
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_then};
 use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::is_must_use_ty;
-use clippy_utils::{match_def_path, must_use_attr, return_ty, trait_ref_of_method};
+use clippy_utils::{match_def_path, return_ty, trait_ref_of_method};
 
 use super::{DOUBLE_MUST_USE, MUST_USE_CANDIDATE, MUST_USE_UNIT};
 
 pub(super) fn check_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
     let attrs = cx.tcx.hir().attrs(item.hir_id());
-    let attr = must_use_attr(attrs);
+    let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
     if let hir::ItemKind::Fn(ref sig, _generics, ref body_id) = item.kind {
         let is_public = cx.access_levels.is_exported(item.def_id);
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
@@ -44,7 +44,7 @@ pub(super) fn check_impl_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Imp
         let is_public = cx.access_levels.is_exported(item.def_id);
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
         let attrs = cx.tcx.hir().attrs(item.hir_id());
-        let attr = must_use_attr(attrs);
+        let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
         if let Some(attr) = attr {
             check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
         } else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.def_id).is_none() {
@@ -67,7 +67,7 @@ pub(super) fn check_trait_item<'tcx>(cx: &LateContext<'tcx>, item: &'tcx hir::Tr
         let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
 
         let attrs = cx.tcx.hir().attrs(item.hir_id());
-        let attr = must_use_attr(attrs);
+        let attr = cx.tcx.get_attr(item.def_id.to_def_id(), sym::must_use);
         if let Some(attr) = attr {
             check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
         } else if let hir::TraitFn::Provided(eid) = *eid {

clippy_lints/src/future_not_send.rs

@@ -5,7 +5,7 @@ use rustc_hir::{Body, FnDecl, HirId};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::subst::Subst;
-use rustc_middle::ty::{Opaque, PredicateKind::Trait};
+use rustc_middle::ty::{EarlyBinder, Opaque, PredicateKind::Trait};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::{sym, Span};
 use rustc_trait_selection::traits::error_reporting::suggestions::InferCtxtExt;
@@ -67,7 +67,7 @@ impl<'tcx> LateLintPass<'tcx> for FutureNotSend {
             let preds = cx.tcx.explicit_item_bounds(id);
             let mut is_future = false;
             for &(p, _span) in preds {
-                let p = p.subst(cx.tcx, subst);
+                let p = EarlyBinder(p).subst(cx.tcx, subst);
                 if let Some(trait_pred) = p.to_opt_poly_trait_pred() {
                     if Some(trait_pred.skip_binder().trait_ref.def_id) == cx.tcx.lang_items().future_trait() {
                         is_future = true;

clippy_lints/src/lib.register_all.rs

@@ -278,6 +278,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(self_assignment::SELF_ASSIGNMENT),
     LintId::of(self_named_constructors::SELF_NAMED_CONSTRUCTORS),
     LintId::of(serde_api::SERDE_API_MISUSE),
+    LintId::of(significant_drop_in_scrutinee::SIGNIFICANT_DROP_IN_SCRUTINEE),
     LintId::of(single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS),
     LintId::of(size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT),
     LintId::of(slow_vector_initialization::SLOW_VECTOR_INITIALIZATION),

clippy_lints/src/lib.register_lints.rs

@@ -473,6 +473,7 @@ store.register_lints(&[
     shadow::SHADOW_REUSE,
     shadow::SHADOW_SAME,
     shadow::SHADOW_UNRELATED,
+    significant_drop_in_scrutinee::SIGNIFICANT_DROP_IN_SCRUTINEE,
     single_char_lifetime_names::SINGLE_CHAR_LIFETIME_NAMES,
     single_component_path_imports::SINGLE_COMPONENT_PATH_IMPORTS,
     size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT,

clippy_lints/src/lib.register_suspicious.rs

@@ -27,6 +27,7 @@ store.register_group(true, "clippy::suspicious", Some("clippy_suspicious"), vec!
     LintId::of(mut_key::MUTABLE_KEY_TYPE),
     LintId::of(octal_escapes::OCTAL_ESCAPES),
     LintId::of(rc_clone_in_vec_init::RC_CLONE_IN_VEC_INIT),
+    LintId::of(significant_drop_in_scrutinee::SIGNIFICANT_DROP_IN_SCRUTINEE),
     LintId::of(suspicious_trait_impl::SUSPICIOUS_ARITHMETIC_IMPL),
     LintId::of(suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL),
 ])

clippy_lints/src/lib.rs

@@ -367,6 +367,7 @@ mod self_named_constructors;
 mod semicolon_if_nothing_returned;
 mod serde_api;
 mod shadow;
+mod significant_drop_in_scrutinee;
 mod single_char_lifetime_names;
 mod single_component_path_imports;
 mod size_of_in_element_count;
@@ -886,6 +887,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(move || Box::new(manual_bits::ManualBits::new(msrv)));
     store.register_late_pass(|| Box::new(default_union_representation::DefaultUnionRepresentation));
     store.register_late_pass(|| Box::new(only_used_in_recursion::OnlyUsedInRecursion));
+    store.register_late_pass(|| Box::new(significant_drop_in_scrutinee::SignificantDropInScrutinee));
     store.register_late_pass(|| Box::new(dbg_macro::DbgMacro));
     let cargo_ignore_publish = conf.cargo_ignore_publish;
     store.register_late_pass(move || {

clippy_lints/src/lifetimes.rs

@@ -9,8 +9,8 @@ use rustc_hir::intravisit::{
 use rustc_hir::FnRetTy::Return;
 use rustc_hir::{
     BareFnTy, BodyId, FnDecl, GenericArg, GenericBound, GenericParam, GenericParamKind, Generics, Impl, ImplItem,
-    ImplItemKind, Item, ItemKind, LangItem, Lifetime, LifetimeName, ParamName, PolyTraitRef, TraitBoundModifier,
+    ImplItemKind, Item, ItemKind, LangItem, Lifetime, LifetimeName, ParamName, PolyTraitRef, PredicateOrigin,
-    TraitFn, TraitItem, TraitItemKind, Ty, TyKind, WherePredicate,
+    TraitBoundModifier, TraitFn, TraitItem, TraitItemKind, Ty, TyKind, WherePredicate,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::nested_filter as middle_nested_filter;
@@ -145,7 +145,7 @@ fn check_fn_inner<'tcx>(
         .filter(|param| matches!(param.kind, GenericParamKind::Type { .. }));
     for typ in types {
         for pred in generics.bounds_for_param(cx.tcx.hir().local_def_id(typ.hir_id)) {
-            if pred.in_where_clause {
+            if pred.origin == PredicateOrigin::WhereClause {
                 // has_where_lifetimes checked that this predicate contains no lifetime.
                 continue;
             }

clippy_lints/src/manual_non_exhaustive.rs

@@ -1,7 +1,6 @@
-use clippy_utils::attrs::is_doc_hidden;
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::snippet_opt;
-use clippy_utils::{is_lint_allowed, meets_msrv, msrvs};
+use clippy_utils::{is_doc_hidden, is_lint_allowed, meets_msrv, msrvs};
 use rustc_ast::ast::{self, VisibilityKind};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -161,7 +160,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualNonExhaustiveEnum {
                 let id = cx.tcx.hir().local_def_id(v.id);
                 (matches!(v.data, hir::VariantData::Unit(_))
                     && v.ident.as_str().starts_with('_')
-                    && is_doc_hidden(cx.tcx.get_attrs(id.to_def_id())))
+                    && is_doc_hidden(cx.tcx.hir().attrs(v.id)))
                 .then(|| (id, v.span))
             });
             if let Some((id, span)) = iter.next()

clippy_lints/src/matches/match_wild_enum.rs

@@ -192,6 +192,5 @@ impl<'a> CommonPrefixSearcher<'a> {
 }
 
 fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
-    let attrs = cx.tcx.get_attrs(variant_def.def_id);
+    cx.tcx.is_doc_hidden(variant_def.def_id) || cx.tcx.has_attr(variant_def.def_id, sym::unstable)
-    clippy_utils::attrs::is_doc_hidden(attrs) || clippy_utils::attrs::is_unstable(attrs)
 }

clippy_lints/src/mut_reference.rs

@@ -48,7 +48,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryMutPassed {
             ExprKind::MethodCall(path, arguments, _) => {
                 let def_id = cx.typeck_results().type_dependent_def_id(e.hir_id).unwrap();
                 let substs = cx.typeck_results().node_substs(e.hir_id);
-                let method_type = cx.tcx.type_of(def_id).subst(cx.tcx, substs);
+                let method_type = cx.tcx.bound_type_of(def_id).subst(cx.tcx, substs);
                 check_arguments(cx, arguments, method_type, path.ident.as_str(), "method");
             },
             _ => (),

clippy_lints/src/new_without_default.rs

@@ -84,7 +84,7 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
                             // can't be implemented for unsafe new
                             return;
                         }
-                        if clippy_utils::is_doc_hidden(cx.tcx.hir().attrs(id)) {
+                        if cx.tcx.is_doc_hidden(impl_item.def_id) {
                             // shouldn't be implemented when it is hidden in docs
                             return;
                         }

clippy_lints/src/only_used_in_recursion.rs

@@ -596,7 +596,7 @@ impl<'tcx> SideEffectVisit<'tcx> {
                 let mut vars = std::mem::take(&mut self.ret_vars);
                 let _ = arm.guard.as_ref().map(|guard| {
                     self.visit_expr(match guard {
-                        Guard::If(expr) | Guard::IfLet(_, expr) => expr,
+                        Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => expr,
                     });
                     vars.append(&mut self.ret_vars);
                 });

clippy_lints/src/partialeq_ne_impl.rs

@@ -1,5 +1,4 @@
 use clippy_utils::diagnostics::span_lint_hir;
-use clippy_utils::is_automatically_derived;
 use if_chain::if_chain;
 use rustc_hir::{Impl, Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -37,8 +36,7 @@ impl<'tcx> LateLintPass<'tcx> for PartialEqNeImpl {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
         if_chain! {
             if let ItemKind::Impl(Impl { of_trait: Some(ref trait_ref), items: impl_items, .. }) = item.kind;
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
+            if !cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
-            if !is_automatically_derived(attrs);
             if let Some(eq_trait) = cx.tcx.lang_items().eq_trait();
             if trait_ref.path.res.def_id() == eq_trait;
             then {

clippy_lints/src/redundant_clone.rs

@@ -113,7 +113,7 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClone {
             }
 
             // Give up on loops
-            if terminator.successors().any(|s| *s == bb) {
+            if terminator.successors().any(|s| s == bb) {
                 continue;
             }
 
@@ -439,7 +439,7 @@ fn visit_clone_usage(cloned: mir::Local, clone: mir::Local, mir: &mir::Body<'_>,
             // Short-circuit
             if (usage.cloned_used && usage.clone_consumed_or_mutated) ||
                 // Give up on loops
-                tdata.terminator().successors().any(|s| *s == bb)
+                tdata.terminator().successors().any(|s| s == bb)
             {
                 return CloneUsage {
                     cloned_used: true,

clippy_lints/src/same_name_method.rs

@@ -51,7 +51,7 @@ impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
         let mut map = FxHashMap::<Res, ExistingName>::default();
 
         for id in cx.tcx.hir().items() {
-            if matches!(cx.tcx.hir().def_kind(id.def_id), DefKind::Impl)
+            if matches!(cx.tcx.def_kind(id.def_id), DefKind::Impl)
                 && let item = cx.tcx.hir().item(id)
                 && let ItemKind::Impl(Impl {
                     items,

clippy_lints/src/significant_drop_in_scrutinee.rs

@@ -0,0 +1,406 @@
+use crate::FxHashSet;
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::get_attr;
+use clippy_utils::source::{indent_of, snippet};
+use rustc_errors::{Applicability, Diagnostic};
+use rustc_hir::intravisit::{walk_expr, Visitor};
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::ty::subst::GenericArgKind;
+use rustc_middle::ty::{Ty, TypeAndMut};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::Span;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Check for temporaries returned from function calls in a match scrutinee that have the
+    /// `clippy::has_significant_drop` attribute.
+    ///
+    /// ### Why is this bad?
+    /// The `clippy::has_significant_drop` attribute can be added to types whose Drop impls have
+    /// an important side-effect, such as unlocking a mutex, making it important for users to be
+    /// able to accurately understand their lifetimes. When a temporary is returned in a function
+    /// call in a match scrutinee, its lifetime lasts until the end of the match block, which may
+    /// be surprising.
+    ///
+    /// For `Mutex`es this can lead to a deadlock. This happens when the match scrutinee uses a
+    /// function call that returns a `MutexGuard` and then tries to lock again in one of the match
+    /// arms. In that case the `MutexGuard` in the scrutinee will not be dropped until the end of
+    /// the match block and thus will not unlock.
+    ///
+    /// ### Example
+    /// ```rust.ignore
+    /// # use std::sync::Mutex;
+    ///
+    /// # struct State {}
+    ///
+    /// # impl State {
+    /// #     fn foo(&self) -> bool {
+    /// #         true
+    /// #     }
+    ///
+    /// #     fn bar(&self) {}
+    /// # }
+    ///
+    ///
+    /// let mutex = Mutex::new(State {});
+    ///
+    /// match mutex.lock().unwrap().foo() {
+    ///     true => {
+    ///         mutex.lock().unwrap().bar(); // Deadlock!
+    ///     }
+    ///     false => {}
+    /// };
+    ///
+    /// println!("All done!");
+    ///
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// # use std::sync::Mutex;
+    ///
+    /// # struct State {}
+    ///
+    /// # impl State {
+    /// #     fn foo(&self) -> bool {
+    /// #         true
+    /// #     }
+    ///
+    /// #     fn bar(&self) {}
+    /// # }
+    ///
+    /// let mutex = Mutex::new(State {});
+    ///
+    /// let is_foo = mutex.lock().unwrap().foo();
+    /// match is_foo {
+    ///     true => {
+    ///         mutex.lock().unwrap().bar();
+    ///     }
+    ///     false => {}
+    /// };
+    ///
+    /// println!("All done!");
+    /// ```
+    #[clippy::version = "1.60.0"]
+    pub SIGNIFICANT_DROP_IN_SCRUTINEE,
+    suspicious,
+    "warns when a temporary of a type with a drop with a significant side-effect might have a surprising lifetime"
+}
+
+declare_lint_pass!(SignificantDropInScrutinee => [SIGNIFICANT_DROP_IN_SCRUTINEE]);
+
+impl<'tcx> LateLintPass<'tcx> for SignificantDropInScrutinee {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
+        if let Some(suggestions) = has_significant_drop_in_scrutinee(cx, expr) {
+            for found in suggestions {
+                span_lint_and_then(
+                    cx,
+                    SIGNIFICANT_DROP_IN_SCRUTINEE,
+                    found.found_span,
+                    "temporary with significant drop in match scrutinee",
+                    |diag| set_diagnostic(diag, cx, expr, found),
+                );
+            }
+        }
+    }
+}
+
+fn set_diagnostic<'tcx>(diag: &mut Diagnostic, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, found: FoundSigDrop) {
+    if found.lint_suggestion == LintSuggestion::MoveAndClone {
+        // If our suggestion is to move and clone, then we want to leave it to the user to
+        // decide how to address this lint, since it may be that cloning is inappropriate.
+        // Therefore, we won't to emit a suggestion.
+        return;
+    }
+
+    let original = snippet(cx, found.found_span, "..");
+    let trailing_indent = " ".repeat(indent_of(cx, found.found_span).unwrap_or(0));
+
+    let replacement = if found.lint_suggestion == LintSuggestion::MoveAndDerefToCopy {
+        format!("let value = *{};\n{}", original, trailing_indent)
+    } else if found.is_unit_return_val {
+        // If the return value of the expression to be moved is unit, then we don't need to
+        // capture the result in a temporary -- we can just replace it completely with `()`.
+        format!("{};\n{}", original, trailing_indent)
+    } else {
+        format!("let value = {};\n{}", original, trailing_indent)
+    };
+
+    let suggestion_message = if found.lint_suggestion == LintSuggestion::MoveOnly {
+        "try moving the temporary above the match"
+    } else {
+        "try moving the temporary above the match and create a copy"
+    };
+
+    let scrutinee_replacement = if found.is_unit_return_val {
+        "()".to_owned()
+    } else {
+        "value".to_owned()
+    };
+
+    diag.multipart_suggestion(
+        suggestion_message,
+        vec![
+            (expr.span.shrink_to_lo(), replacement),
+            (found.found_span, scrutinee_replacement),
+        ],
+        Applicability::MaybeIncorrect,
+    );
+}
+
+/// 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, 'a>(
+    cx: &'a LateContext<'tcx>,
+    expr: &'tcx Expr<'tcx>,
+) -> Option<Vec<FoundSigDrop>> {
+    let mut helper = SigDropHelper::new(cx);
+    match expr.kind {
+        ExprKind::Match(match_expr, _, _) => helper.find_sig_drop(match_expr),
+        _ => None,
+    }
+}
+
+struct SigDropHelper<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    is_chain_end: bool,
+    seen_types: FxHashSet<Ty<'tcx>>,
+    has_significant_drop: bool,
+    current_sig_drop: Option<FoundSigDrop>,
+    sig_drop_spans: Option<Vec<FoundSigDrop>>,
+    special_handling_for_binary_op: bool,
+}
+
+#[expect(clippy::enum_variant_names)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+enum LintSuggestion {
+    MoveOnly,
+    MoveAndDerefToCopy,
+    MoveAndClone,
+}
+
+#[derive(Clone, Copy)]
+struct FoundSigDrop {
+    found_span: Span,
+    is_unit_return_val: bool,
+    lint_suggestion: LintSuggestion,
+}
+
+impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>) -> SigDropHelper<'a, 'tcx> {
+        SigDropHelper {
+            cx,
+            is_chain_end: true,
+            seen_types: FxHashSet::default(),
+            has_significant_drop: false,
+            current_sig_drop: None,
+            sig_drop_spans: None,
+            special_handling_for_binary_op: false,
+        }
+    }
+
+    fn find_sig_drop(&mut self, match_expr: &'tcx Expr<'_>) -> Option<Vec<FoundSigDrop>> {
+        self.visit_expr(match_expr);
+
+        // If sig drop spans is empty but we found a significant drop, it means that we didn't find
+        // a type that was trivially copyable as we moved up the chain after finding a significant
+        // drop, so move the entire scrutinee.
+        if self.has_significant_drop && self.sig_drop_spans.is_none() {
+            self.try_setting_current_suggestion(match_expr, true);
+            self.move_current_suggestion();
+        }
+
+        self.sig_drop_spans.take()
+    }
+
+    /// This will try to set the current suggestion (so it can be moved into the suggestions vec
+    /// later). If `allow_move_and_clone` is false, the suggestion *won't* be set -- this gives us
+    /// an opportunity to look for another type in the chain that will be trivially copyable.
+    /// However, if we are at the the end of the chain, we want to accept whatever is there. (The
+    /// suggestion won't actually be output, but the diagnostic message will be output, so the user
+    /// can determine the best way to handle the lint.)
+    fn try_setting_current_suggestion(&mut self, expr: &'tcx Expr<'_>, allow_move_and_clone: bool) {
+        if self.current_sig_drop.is_some() {
+            return;
+        }
+        let ty = self.get_type(expr);
+        if ty.is_ref() {
+            // We checked that the type was ref, so builtin_deref will return Some TypeAndMut,
+            // but let's avoid any chance of an ICE
+            if let Some(TypeAndMut { ty, .. }) = ty.builtin_deref(true) {
+                if ty.is_trivially_pure_clone_copy() {
+                    self.current_sig_drop.replace(FoundSigDrop {
+                        found_span: expr.span,
+                        is_unit_return_val: false,
+                        lint_suggestion: LintSuggestion::MoveAndDerefToCopy,
+                    });
+                } else if allow_move_and_clone {
+                    self.current_sig_drop.replace(FoundSigDrop {
+                        found_span: expr.span,
+                        is_unit_return_val: false,
+                        lint_suggestion: LintSuggestion::MoveAndClone,
+                    });
+                }
+            }
+        } else if ty.is_trivially_pure_clone_copy() {
+            self.current_sig_drop.replace(FoundSigDrop {
+                found_span: expr.span,
+                is_unit_return_val: false,
+                lint_suggestion: LintSuggestion::MoveOnly,
+            });
+        }
+    }
+
+    fn move_current_suggestion(&mut self) {
+        if let Some(current) = self.current_sig_drop.take() {
+            self.sig_drop_spans.get_or_insert_with(Vec::new).push(current);
+        }
+    }
+
+    fn get_type(&self, ex: &'tcx Expr<'_>) -> Ty<'tcx> {
+        self.cx.typeck_results().expr_ty(ex)
+    }
+
+    fn has_seen_type(&mut self, ty: Ty<'tcx>) -> bool {
+        !self.seen_types.insert(ty)
+    }
+
+    fn visit_exprs_for_binary_ops(
+        &mut self,
+        left: &'tcx Expr<'_>,
+        right: &'tcx Expr<'_>,
+        is_unit_return_val: bool,
+        span: Span,
+    ) {
+        self.special_handling_for_binary_op = true;
+        self.visit_expr(left);
+        self.visit_expr(right);
+
+        // If either side had a significant drop, suggest moving the entire scrutinee to avoid
+        // unnecessary copies and to simplify cases where both sides have significant drops.
+        if self.has_significant_drop {
+            self.current_sig_drop.replace(FoundSigDrop {
+                found_span: span,
+                is_unit_return_val,
+                lint_suggestion: LintSuggestion::MoveOnly,
+            });
+        }
+
+        self.special_handling_for_binary_op = false;
+    }
+
+    fn has_sig_drop_attr(&mut self, cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
+        if let Some(adt) = ty.ty_adt_def() {
+            if get_attr(cx.sess(), cx.tcx.get_attrs_unchecked(adt.did()), "has_significant_drop").count() > 0 {
+                return true;
+            }
+        }
+
+        match ty.kind() {
+            rustc_middle::ty::Adt(a, b) => {
+                for f in a.all_fields() {
+                    let ty = f.ty(cx.tcx, b);
+                    if !self.has_seen_type(ty) && self.has_sig_drop_attr(cx, ty) {
+                        return true;
+                    }
+                }
+
+                for generic_arg in b.iter() {
+                    if let GenericArgKind::Type(ty) = generic_arg.unpack() {
+                        if self.has_sig_drop_attr(cx, ty) {
+                            return true;
+                        }
+                    }
+                }
+                false
+            },
+            rustc_middle::ty::Array(ty, _)
+            | rustc_middle::ty::RawPtr(TypeAndMut { ty, .. })
+            | rustc_middle::ty::Ref(_, ty, _)
+            | rustc_middle::ty::Slice(ty) => self.has_sig_drop_attr(cx, *ty),
+            _ => false,
+        }
+    }
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for SigDropHelper<'a, 'tcx> {
+    fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
+        if !self.is_chain_end && self.has_sig_drop_attr(self.cx, self.get_type(ex)) {
+            self.has_significant_drop = true;
+            return;
+        }
+        self.is_chain_end = false;
+
+        match ex.kind {
+            ExprKind::MethodCall(_, [ref expr, ..], _) => {
+                self.visit_expr(expr);
+            }
+            ExprKind::Binary(_, left, right) => {
+                self.visit_exprs_for_binary_ops(left, right, false, ex.span);
+            }
+            ExprKind::Assign(left, right, _) | ExprKind::AssignOp(_, left, right) => {
+                self.visit_exprs_for_binary_ops(left, right, true, ex.span);
+            }
+            ExprKind::Tup(exprs) => {
+                for expr in exprs {
+                    self.visit_expr(expr);
+                    if self.has_significant_drop {
+                        // We may have not have set current_sig_drop if all the suggestions were
+                        // MoveAndClone, so add this tuple item's full expression in that case.
+                        if self.current_sig_drop.is_none() {
+                            self.try_setting_current_suggestion(expr, true);
+                        }
+
+                        // Now we are guaranteed to have something, so add it to the final vec.
+                        self.move_current_suggestion();
+                    }
+                    // Reset `has_significant_drop` after each tuple expression so we can look for
+                    // additional cases.
+                    self.has_significant_drop = false;
+                }
+                if self.sig_drop_spans.is_some() {
+                    self.has_significant_drop = true;
+                }
+            }
+            ExprKind::Box(..) |
+                ExprKind::Array(..) |
+                ExprKind::Call(..) |
+                ExprKind::Unary(..) |
+                ExprKind::If(..) |
+                ExprKind::Match(..) |
+                ExprKind::Field(..) |
+                ExprKind::Index(..) |
+                ExprKind::Ret(..) |
+                ExprKind::Repeat(..) |
+                ExprKind::Yield(..) |
+                ExprKind::MethodCall(..) => walk_expr(self, ex),
+            ExprKind::AddrOf(_, _, _) |
+                ExprKind::Block(_, _) |
+                ExprKind::Break(_, _) |
+                ExprKind::Cast(_, _) |
+                // Don't want to check the closure itself, only invocation, which is covered by MethodCall
+                ExprKind::Closure(_, _, _, _, _) |
+                ExprKind::ConstBlock(_) |
+                ExprKind::Continue(_) |
+                ExprKind::DropTemps(_) |
+                ExprKind::Err |
+                ExprKind::InlineAsm(_) |
+                ExprKind::Let(_) |
+                ExprKind::Lit(_) |
+                ExprKind::Loop(_, _, _, _) |
+                ExprKind::Path(_) |
+                ExprKind::Struct(_, _, _) |
+                ExprKind::Type(_, _) => {
+                return;
+            }
+        }
+
+        // Once a significant temporary has been found, we need to go back up at least 1 level to
+        // find the span to extract for replacement, so the temporary gets dropped. However, for
+        // binary ops, we want to move the whole scrutinee so we avoid unnecessary copies and to
+        // simplify cases where both sides have significant drops.
+        if self.has_significant_drop && !self.special_handling_for_binary_op {
+            self.try_setting_current_suggestion(ex, false);
+        }
+    }
+}

clippy_lints/src/trait_bounds.rs

@@ -8,7 +8,8 @@ use rustc_data_structures::unhash::UnhashMap;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::{
-    GenericBound, Generics, Item, ItemKind, Node, Path, PathSegment, QPath, TraitItem, Ty, TyKind, WherePredicate,
+    GenericBound, Generics, Item, ItemKind, Node, Path, PathSegment, PredicateOrigin, QPath, TraitItem, Ty, TyKind,
+    WherePredicate,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
@@ -95,6 +96,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
         for predicate in item.generics.predicates {
             if_chain! {
                 if let WherePredicate::BoundPredicate(ref bound_predicate) = predicate;
+                if bound_predicate.origin != PredicateOrigin::ImplTrait;
                 if !bound_predicate.span.from_expansion();
                 if let TyKind::Path(QPath::Resolved(_, Path { segments, .. })) = bound_predicate.bounded_ty.kind;
                 if let Some(PathSegment {
@@ -168,6 +170,7 @@ impl TraitBounds {
         for bound in gen.predicates {
             if_chain! {
                 if let WherePredicate::BoundPredicate(ref p) = bound;
+                if p.origin != PredicateOrigin::ImplTrait;
                 if p.bounds.len() as u64 <= self.max_trait_bounds;
                 if !p.span.from_expansion();
                 if let Some(ref v) = map.insert(
@@ -223,6 +226,7 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
     for predicate in gen.predicates {
         if_chain! {
             if let WherePredicate::BoundPredicate(ref bound_predicate) = predicate;
+            if bound_predicate.origin != PredicateOrigin::ImplTrait;
             if !bound_predicate.span.from_expansion();
             if let TyKind::Path(QPath::Resolved(_, Path { segments, .. })) = bound_predicate.bounded_ty.kind;
             if let Some(segment) = segments.first();

clippy_lints/src/transmute/transmute_undefined_repr.rs

@@ -307,7 +307,7 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
                     .non_enum_variant()
                     .fields
                     .iter()
-                    .map(|f| cx.tcx.type_of(f.did).subst(cx.tcx, substs));
+                    .map(|f| cx.tcx.bound_type_of(f.did).subst(cx.tcx, substs));
                 let Some(sized_ty) = iter.find(|&ty| !is_zero_sized_ty(cx, ty)) else {
                     return ReducedTy::TypeErasure;
                 };

clippy_lints/src/utils/author.rs

@@ -315,11 +315,11 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
                 out!("if let Some(Guard::If({expr})) = {arm}.guard;");
                 self.expr(expr);
             },
-            Some(hir::Guard::IfLet(pat, expr)) => {
+            Some(hir::Guard::IfLet(let_expr)) => {
-                bind!(self, pat, expr);
+                bind!(self, let_expr);
-                out!("if let Some(Guard::IfLet({pat}, {expr}) = {arm}.guard;");
+                out!("if let Some(Guard::IfLet({let_expr}) = {arm}.guard;");
-                self.pat(pat);
+                self.pat(field!(let_expr.pat));
-                self.expr(expr);
+                self.expr(field!(let_expr.init));
             },
         }
         self.expr(field!(arm.body));

clippy_utils/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "clippy_utils"
-version = "0.1.62"
+version = "0.1.63"
 edition = "2021"
 publish = false
 

clippy_utils/src/attrs.rs

@@ -1,4 +1,5 @@
-use rustc_ast::{ast, attr};
+use rustc_ast::ast;
+use rustc_ast::attr;
 use rustc_errors::Applicability;
 use rustc_session::Session;
 use rustc_span::sym;
@@ -21,6 +22,7 @@ pub const BUILTIN_ATTRIBUTES: &[(&str, DeprecationStatus)] = &[
     ("cyclomatic_complexity", DeprecationStatus::Replaced("cognitive_complexity")),
     ("dump",                  DeprecationStatus::None),
     ("msrv",                  DeprecationStatus::None),
+    ("has_significant_drop",  DeprecationStatus::None),
 ];
 
 pub struct LimitStack {
@@ -155,8 +157,3 @@ pub fn is_doc_hidden(attrs: &[ast::Attribute]) -> bool {
         .filter_map(ast::Attribute::meta_item_list)
         .any(|l| attr::list_contains_name(&l, sym::hidden))
 }
-
-/// Return true if the attributes contain `#[unstable]`
-pub fn is_unstable(attrs: &[ast::Attribute]) -> bool {
-    attrs.iter().any(|attr| attr.has_name(sym::unstable))
-}

clippy_utils/src/consts.rs

@@ -9,7 +9,7 @@ use rustc_hir::{BinOp, BinOpKind, Block, Expr, ExprKind, HirId, Item, ItemKind,
 use rustc_lint::LateContext;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::ty::subst::{Subst, SubstsRef};
-use rustc_middle::ty::{self, FloatTy, ScalarInt, Ty, TyCtxt};
+use rustc_middle::ty::{self, EarlyBinder, FloatTy, ScalarInt, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::Symbol;
 use std::cmp::Ordering::{self, Equal};
@@ -417,7 +417,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
                 let substs = if self.substs.is_empty() {
                     substs
                 } else {
-                    substs.subst(self.lcx.tcx, self.substs)
+                    EarlyBinder(substs).subst(self.lcx.tcx, self.substs)
                 };
 
                 let result = self

clippy_utils/src/hir_utils.rs

@@ -300,7 +300,9 @@ impl HirEqInterExpr<'_, '_, '_> {
     fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
         match (left, right) {
             (Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
-            (Guard::IfLet(lp, le), Guard::IfLet(rp, re)) => self.eq_pat(lp, rp) && self.eq_expr(le, re),
+            (Guard::IfLet(l), Guard::IfLet(r)) => {
+                self.eq_pat(l.pat, r.pat) && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r)) && self.eq_expr(l.init, r.init)
+            },
             _ => false,
         }
     }
@@ -892,7 +894,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
 
     pub fn hash_guard(&mut self, g: &Guard<'_>) {
         match g {
-            Guard::If(expr) | Guard::IfLet(_, expr) => {
+            Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
                 self.hash_expr(expr);
             },
         }

clippy_utils/src/lib.rs

@@ -66,7 +66,8 @@ use std::lazy::SyncOnceCell;
 use std::sync::{Mutex, MutexGuard};
 
 use if_chain::if_chain;
-use rustc_ast::ast::{self, Attribute, LitKind};
+use rustc_ast::ast::{self, LitKind};
+use rustc_ast::Attribute;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_hir as hir;
@@ -74,13 +75,12 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_ID};
 use rustc_hir::hir_id::{HirIdMap, HirIdSet};
 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
-use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
 use rustc_hir::{
     def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Constness, Destination, Expr, ExprKind, FnDecl,
-    ForeignItem, HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource,
+    HirId, Impl, ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Mutability, Node,
-    Mutability, Node, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind,
+    Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
-    TraitRef, TyKind, UnOp,
+    UnOp,
 };
 use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::place::PlaceBase;
@@ -1472,12 +1472,6 @@ pub fn recurse_or_patterns<'tcx, F: FnMut(&'tcx Pat<'tcx>)>(pat: &'tcx Pat<'tcx>
     }
 }
 
-/// Checks for the `#[automatically_derived]` attribute all `#[derive]`d
-/// implementations have.
-pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
-    has_attr(attrs, sym::automatically_derived)
-}
-
 pub fn is_self(slf: &Param<'_>) -> bool {
     if let PatKind::Binding(.., name, _) = slf.pat.kind {
         name.name == kw::SelfLower
@@ -1724,11 +1718,6 @@ pub fn get_async_fn_body<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'_>) -> Option<&'t
     None
 }
 
-// Finds the `#[must_use]` attribute, if any
-pub fn must_use_attr(attrs: &[Attribute]) -> Option<&Attribute> {
-    attrs.iter().find(|a| a.has_name(sym::must_use))
-}
-
 // check if expr is calling method or function with #[must_use] attribute
 pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     let did = match expr.kind {
@@ -1745,7 +1734,7 @@ pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         _ => None,
     };
 
-    did.map_or(false, |did| must_use_attr(cx.tcx.get_attrs(did)).is_some())
+    did.map_or(false, |did| cx.tcx.has_attr(did, sym::must_use))
 }
 
 /// Checks if an expression represents the identity function
@@ -2079,35 +2068,6 @@ pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
     false
 }
 
-struct TestItemNamesVisitor<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    names: Vec<Symbol>,
-}
-
-impl<'hir> ItemLikeVisitor<'hir> for TestItemNamesVisitor<'hir> {
-    fn visit_item(&mut self, item: &Item<'_>) {
-        if let ItemKind::Const(ty, _body) = item.kind {
-            if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
-                // We could also check for the type name `test::TestDescAndFn`
-                if let Res::Def(DefKind::Struct, _) = path.res {
-                    let has_test_marker = self
-                        .tcx
-                        .hir()
-                        .attrs(item.hir_id())
-                        .iter()
-                        .any(|a| a.has_name(sym::rustc_test_marker));
-                    if has_test_marker {
-                        self.names.push(item.ident.name);
-                    }
-                }
-            }
-        }
-    }
-    fn visit_trait_item(&mut self, _: &TraitItem<'_>) {}
-    fn visit_impl_item(&mut self, _: &ImplItem<'_>) {}
-    fn visit_foreign_item(&mut self, _: &ForeignItem<'_>) {}
-}
-
 static TEST_ITEM_NAMES_CACHE: SyncOnceCell<Mutex<FxHashMap<LocalDefId, Vec<Symbol>>>> = SyncOnceCell::new();
 
 fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(&[Symbol]) -> bool) -> bool {
@@ -2116,10 +2076,28 @@ fn with_test_item_names<'tcx>(tcx: TyCtxt<'tcx>, module: LocalDefId, f: impl Fn(
     match map.entry(module) {
         Entry::Occupied(entry) => f(entry.get()),
         Entry::Vacant(entry) => {
-            let mut visitor = TestItemNamesVisitor { tcx, names: Vec::new() };
+            let mut names = Vec::new();
-            tcx.hir().visit_item_likes_in_module(module, &mut visitor);
+            for id in tcx.hir().module_items(module) {
-            visitor.names.sort_unstable();
+                if matches!(tcx.def_kind(id.def_id), DefKind::Const)
-            f(&*entry.insert(visitor.names))
+                    && let item = tcx.hir().item(id)
+                    && let ItemKind::Const(ty, _body) = item.kind {
+                    if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind {
+                        // We could also check for the type name `test::TestDescAndFn`
+                        if let Res::Def(DefKind::Struct, _) = path.res {
+                            let has_test_marker = tcx
+                                .hir()
+                                .attrs(item.hir_id())
+                                .iter()
+                                .any(|a| a.has_name(sym::rustc_test_marker));
+                            if has_test_marker {
+                                names.push(item.ident.name);
+                            }
+                        }
+                    }
+                }
+            }
+            names.sort_unstable();
+            f(&*entry.insert(names))
         },
     }
 }

clippy_utils/src/qualify_min_const_fn.rs

@@ -14,7 +14,6 @@ use rustc_middle::ty::{self, adjustment::PointerCast, Ty, TyCtxt};
 use rustc_semver::RustcVersion;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
-use rustc_target::spec::abi::Abi::RustIntrinsic;
 use std::borrow::Cow;
 
 type McfResult = Result<(), (Span, Cow<'static, str>)>;
@@ -323,7 +322,7 @@ fn check_terminator<'a, 'tcx>(
                 // within const fns. `transmute` is allowed in all other const contexts.
                 // This won't really scale to more intrinsics or functions. Let's allow const
                 // transmutes in const fn before we add more hacks to this.
-                if tcx.fn_sig(fn_def_id).abi() == RustIntrinsic && tcx.item_name(fn_def_id) == sym::transmute {
+                if tcx.is_intrinsic(fn_def_id) && tcx.item_name(fn_def_id) == sym::transmute {
                     return Err((
                         span,
                         "can only call `transmute` from const items, not `const fn`".into(),

clippy_utils/src/ty.rs

@@ -22,7 +22,7 @@ use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::query::normalize::AtExt;
 use std::iter;
 
-use crate::{match_def_path, must_use_attr, path_res, paths};
+use crate::{match_def_path, path_res, paths};
 
 // Checks if the given type implements copy.
 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
@@ -178,18 +178,18 @@ pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
 // Returns whether the type has #[must_use] attribute
 pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
     match ty.kind() {
-        ty::Adt(adt, _) => must_use_attr(cx.tcx.get_attrs(adt.did())).is_some(),
+        ty::Adt(adt, _) => cx.tcx.has_attr(adt.did(), sym::must_use),
-        ty::Foreign(ref did) => must_use_attr(cx.tcx.get_attrs(*did)).is_some(),
+        ty::Foreign(did) => cx.tcx.has_attr(*did, sym::must_use),
         ty::Slice(ty) | ty::Array(ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
             // for the Array case we don't need to care for the len == 0 case
             // because we don't want to lint functions returning empty arrays
             is_must_use_ty(cx, *ty)
         },
         ty::Tuple(substs) => substs.iter().any(|ty| is_must_use_ty(cx, ty)),
-        ty::Opaque(ref def_id, _) => {
+        ty::Opaque(def_id, _) => {
             for (predicate, _) in cx.tcx.explicit_item_bounds(*def_id) {
                 if let ty::PredicateKind::Trait(trait_predicate) = predicate.kind().skip_binder() {
-                    if must_use_attr(cx.tcx.get_attrs(trait_predicate.trait_ref.def_id)).is_some() {
+                    if cx.tcx.has_attr(trait_predicate.trait_ref.def_id, sym::must_use) {
                         return true;
                     }
                 }
@@ -199,7 +199,7 @@ pub fn is_must_use_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         ty::Dynamic(binder, _) => {
             for predicate in binder.iter() {
                 if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
-                    if must_use_attr(cx.tcx.get_attrs(trait_ref.def_id)).is_some() {
+                    if cx.tcx.has_attr(trait_ref.def_id, sym::must_use) {
                         return true;
                     }
                 }
@@ -520,7 +520,7 @@ pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnS
         let ty = cx.typeck_results().expr_ty_adjusted(expr).peel_refs();
         match *ty.kind() {
             ty::Closure(_, subs) => Some(ExprFnSig::Closure(subs.as_closure().sig())),
-            ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.fn_sig(id).subst(cx.tcx, subs))),
+            ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs))),
             ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig)),
             ty::Dynamic(bounds, _) => {
                 let lang_items = cx.tcx.lang_items();

rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2022-05-05"
+channel = "nightly-2022-05-19"
 components = ["cargo", "llvm-tools-preview", "rust-src", "rust-std", "rustc", "rustc-dev", "rustfmt"]

tests/ui/crashes/ice-6252.stderr

@@ -30,7 +30,15 @@ LL |     const VAL: T;
 LL | impl<N, M> TypeVal<usize> for Multiply<N, M> where N: TypeVal<VAL> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `VAL` in implementation
 
-error: aborting due to 3 previous errors
+error: constant expression depends on a generic parameter
+  --> $DIR/ice-6252.rs:13:9
+   |
+LL |     [1; <Multiply<Five, Five>>::VAL];
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0046, E0412.
 For more information about an error, try `rustc --explain E0046`.

tests/ui/expect_tool_lint_rfc_2383.rs

@@ -0,0 +1,142 @@
+// check-pass
+#![feature(lint_reasons)]
+//! This file tests the `#[expect]` attribute implementation for tool lints. The same
+//! file is used to test clippy and rustdoc. Any changes to this file should be synced
+//! to the other test files as well.
+//!
+//! Expectations:
+//! * rustc: only rustc lint expectations are emitted
+//! * clippy: rustc and Clippy's expectations are emitted
+//! * rustdoc: only rustdoc lint expectations are emitted
+//!
+//! This test can't cover every lint from Clippy, rustdoc and potentially other
+//! tools that will be developed. This therefore only tests a small subset of lints
+#![expect(rustdoc::missing_crate_level_docs)]
+
+mod rustc_ok {
+    //! See <https://doc.rust-lang.org/rustc/lints/index.html>
+
+    #[expect(dead_code)]
+    pub fn rustc_lints() {
+        let x = 42.0;
+
+        #[expect(illegal_floating_point_literal_pattern)]
+        match x {
+            5.0 => {},
+            6.0 => {},
+            _ => {},
+        }
+    }
+}
+
+mod rustc_warn {
+    //! See <https://doc.rust-lang.org/rustc/lints/index.html>
+
+    #[expect(dead_code)]
+    pub fn rustc_lints() {
+        let x = 42;
+
+        #[expect(illegal_floating_point_literal_pattern)]
+        match x {
+            5 => {},
+            6 => {},
+            _ => {},
+        }
+    }
+}
+
+pub mod rustdoc_ok {
+    //! See <https://doc.rust-lang.org/rustdoc/lints.html>
+
+    #[expect(rustdoc::broken_intra_doc_links)]
+    /// I want to link to [`Nonexistent`] but it doesn't exist!
+    pub fn foo() {}
+
+    #[expect(rustdoc::invalid_html_tags)]
+    /// <h1>
+    pub fn bar() {}
+
+    #[expect(rustdoc::bare_urls)]
+    /// http://example.org
+    pub fn baz() {}
+}
+
+pub mod rustdoc_warn {
+    //! See <https://doc.rust-lang.org/rustdoc/lints.html>
+
+    #[expect(rustdoc::broken_intra_doc_links)]
+    /// I want to link to [`bar`] but it doesn't exist!
+    pub fn foo() {}
+
+    #[expect(rustdoc::invalid_html_tags)]
+    /// <h1></h1>
+    pub fn bar() {}
+
+    #[expect(rustdoc::bare_urls)]
+    /// <http://example.org>
+    pub fn baz() {}
+}
+
+mod clippy_ok {
+    //! See <https://rust-lang.github.io/rust-clippy/master/index.html>
+
+    #[expect(clippy::almost_swapped)]
+    fn foo() {
+        let mut a = 0;
+        let mut b = 9;
+        a = b;
+        b = a;
+    }
+
+    #[expect(clippy::bytes_nth)]
+    fn bar() {
+        let _ = "Hello".bytes().nth(3);
+    }
+
+    #[expect(clippy::if_same_then_else)]
+    fn baz() {
+        let _ = if true { 42 } else { 42 };
+    }
+
+    #[expect(clippy::logic_bug)]
+    fn burger() {
+        let a = false;
+        let b = true;
+
+        if a && b || a {}
+    }
+}
+
+mod clippy_warn {
+    //! See <https://rust-lang.github.io/rust-clippy/master/index.html>
+
+    #[expect(clippy::almost_swapped)]
+    fn foo() {
+        let mut a = 0;
+        let mut b = 9;
+        a = b;
+    }
+
+    #[expect(clippy::bytes_nth)]
+    fn bar() {
+        let _ = "Hello".as_bytes().get(3);
+    }
+
+    #[expect(clippy::if_same_then_else)]
+    fn baz() {
+        let _ = if true { 33 } else { 42 };
+    }
+
+    #[expect(clippy::logic_bug)]
+    fn burger() {
+        let a = false;
+        let b = true;
+        let c = false;
+
+        if a && b || c {}
+    }
+}
+
+fn main() {
+    rustc_warn::rustc_lints();
+}

tests/ui/expect_tool_lint_rfc_2383.stderr

@@ -0,0 +1,40 @@
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:35:14
+   |
+LL |     #[expect(dead_code)]
+   |              ^^^^^^^^^
+   |
+   = note: `-D unfulfilled-lint-expectations` implied by `-D warnings`
+
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:39:18
+   |
+LL |         #[expect(illegal_floating_point_literal_pattern)]
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:113:14
+   |
+LL |     #[expect(clippy::almost_swapped)]
+   |              ^^^^^^^^^^^^^^^^^^^^^^
+
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:120:14
+   |
+LL |     #[expect(clippy::bytes_nth)]
+   |              ^^^^^^^^^^^^^^^^^
+
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:125:14
+   |
+LL |     #[expect(clippy::if_same_then_else)]
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: this lint expectation is unfulfilled
+  --> $DIR/expect_tool_lint_rfc_2383.rs:130:14
+   |
+LL |     #[expect(clippy::logic_bug)]
+   |              ^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+

tests/ui/indexing_slicing_index.stderr

@@ -1,4 +1,4 @@
-error[E0080]: evaluation of `main::{constant#3}::<&i32>` failed
+error[E0080]: evaluation of `main::{constant#3}` failed
   --> $DIR/indexing_slicing_index.rs:31:14
    |
 LL |     const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.

tests/ui/significant_drop_in_scrutinee.rs

@@ -0,0 +1,555 @@
+// FIXME: Ideally these suggestions would be fixed via rustfix. Blocked by rust-lang/rust#53934
+// // run-rustfix
+
+#![warn(clippy::significant_drop_in_scrutinee)]
+#![allow(clippy::single_match)]
+#![allow(clippy::match_single_binding)]
+#![allow(unused_assignments)]
+#![allow(dead_code)]
+
+use std::ops::Deref;
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::{Mutex, MutexGuard};
+
+struct State {}
+
+impl State {
+    fn foo(&self) -> bool {
+        true
+    }
+
+    fn bar(&self) {}
+}
+
+fn should_not_trigger_lint_with_mutex_guard_outside_match() {
+    let mutex = Mutex::new(State {});
+
+    // Should not trigger lint because the temporary should drop at the `;` on line before the match
+    let is_foo = mutex.lock().unwrap().foo();
+    match is_foo {
+        true => {
+            mutex.lock().unwrap().bar();
+        },
+        false => {},
+    };
+}
+
+fn should_not_trigger_lint_with_mutex_guard_when_taking_ownership_in_match() {
+    let mutex = Mutex::new(State {});
+
+    // Should not trigger lint because the scrutinee is explicitly returning the MutexGuard,
+    // so its lifetime should not be surprising.
+    match mutex.lock() {
+        Ok(guard) => {
+            guard.foo();
+            mutex.lock().unwrap().bar();
+        },
+        _ => {},
+    };
+}
+
+fn should_trigger_lint_with_mutex_guard_in_match_scrutinee() {
+    let mutex = Mutex::new(State {});
+
+    // Should trigger lint because the lifetime of the temporary MutexGuard is surprising because it
+    // is preserved until the end of the match, but there is no clear indication that this is the
+    // case.
+    match mutex.lock().unwrap().foo() {
+        true => {
+            mutex.lock().unwrap().bar();
+        },
+        false => {},
+    };
+}
+
+fn should_not_trigger_lint_for_insignificant_drop() {
+    // Should not trigger lint because there are no temporaries whose drops have a significant
+    // side effect.
+    match 1u64.to_string().is_empty() {
+        true => {
+            println!("It was empty")
+        },
+        false => {
+            println!("It was not empty")
+        },
+    }
+}
+
+struct StateWithMutex {
+    m: Mutex<u64>,
+}
+
+struct MutexGuardWrapper<'a> {
+    mg: MutexGuard<'a, u64>,
+}
+
+impl<'a> MutexGuardWrapper<'a> {
+    fn get_the_value(&self) -> u64 {
+        *self.mg.deref()
+    }
+}
+
+struct MutexGuardWrapperWrapper<'a> {
+    mg: MutexGuardWrapper<'a>,
+}
+
+impl<'a> MutexGuardWrapperWrapper<'a> {
+    fn get_the_value(&self) -> u64 {
+        *self.mg.mg.deref()
+    }
+}
+
+impl StateWithMutex {
+    fn lock_m(&self) -> MutexGuardWrapper<'_> {
+        MutexGuardWrapper {
+            mg: self.m.lock().unwrap(),
+        }
+    }
+
+    fn lock_m_m(&self) -> MutexGuardWrapperWrapper<'_> {
+        MutexGuardWrapperWrapper {
+            mg: MutexGuardWrapper {
+                mg: self.m.lock().unwrap(),
+            },
+        }
+    }
+
+    fn foo(&self) -> bool {
+        true
+    }
+
+    fn bar(&self) {}
+}
+
+fn should_trigger_lint_with_wrapped_mutex() {
+    let s = StateWithMutex { m: Mutex::new(1) };
+
+    // Should trigger lint because a temporary contains a type with a significant drop and its
+    // lifetime is not obvious. Additionally, it is not obvious from looking at the scrutinee that
+    // the temporary contains such a type, making it potentially even more surprising.
+    match s.lock_m().get_the_value() {
+        1 => {
+            println!("Got 1. Is it still 1?");
+            println!("{}", s.lock_m().get_the_value());
+        },
+        2 => {
+            println!("Got 2. Is it still 2?");
+            println!("{}", s.lock_m().get_the_value());
+        },
+        _ => {},
+    }
+    println!("All done!");
+}
+
+fn should_trigger_lint_with_double_wrapped_mutex() {
+    let s = StateWithMutex { m: Mutex::new(1) };
+
+    // Should trigger lint because a temporary contains a type which further contains a type with a
+    // significant drop and its lifetime is not obvious. Additionally, it is not obvious from
+    // looking at the scrutinee that the temporary contains such a type, making it potentially even
+    // more surprising.
+    match s.lock_m_m().get_the_value() {
+        1 => {
+            println!("Got 1. Is it still 1?");
+            println!("{}", s.lock_m().get_the_value());
+        },
+        2 => {
+            println!("Got 2. Is it still 2?");
+            println!("{}", s.lock_m().get_the_value());
+        },
+        _ => {},
+    }
+    println!("All done!");
+}
+
+struct Counter {
+    i: AtomicU64,
+}
+
+#[clippy::has_significant_drop]
+struct CounterWrapper<'a> {
+    counter: &'a Counter,
+}
+
+impl<'a> CounterWrapper<'a> {
+    fn new(counter: &Counter) -> CounterWrapper {
+        counter.i.fetch_add(1, Ordering::Relaxed);
+        CounterWrapper { counter }
+    }
+}
+
+impl<'a> Drop for CounterWrapper<'a> {
+    fn drop(&mut self) {
+        self.counter.i.fetch_sub(1, Ordering::Relaxed);
+    }
+}
+
+impl Counter {
+    fn temp_increment(&self) -> Vec<CounterWrapper> {
+        vec![CounterWrapper::new(self), CounterWrapper::new(self)]
+    }
+}
+
+fn should_trigger_lint_for_vec() {
+    let counter = Counter { i: AtomicU64::new(0) };
+
+    // Should trigger lint because the temporary in the scrutinee returns a collection of types
+    // which have significant drops. The types with significant drops are also non-obvious when
+    // reading the expression in the scrutinee.
+    match counter.temp_increment().len() {
+        2 => {
+            let current_count = counter.i.load(Ordering::Relaxed);
+            println!("Current count {}", current_count);
+            assert_eq!(current_count, 0);
+        },
+        1 => {},
+        3 => {},
+        _ => {},
+    };
+}
+
+struct StateWithField {
+    s: String,
+}
+
+// Should trigger lint only on the type in the tuple which is created using a temporary
+// with a significant drop. Additionally, this test ensures that the format of the tuple
+// is preserved correctly in the suggestion.
+fn should_trigger_lint_for_tuple_in_scrutinee() {
+    let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
+
+    {
+        match (mutex1.lock().unwrap().s.len(), true) {
+            (3, _) => {
+                println!("started");
+                mutex1.lock().unwrap().s.len();
+                println!("done");
+            },
+            (_, _) => {},
+        };
+
+        match (true, mutex1.lock().unwrap().s.len(), true) {
+            (_, 3, _) => {
+                println!("started");
+                mutex1.lock().unwrap().s.len();
+                println!("done");
+            },
+            (_, _, _) => {},
+        };
+
+        let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
+        match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
+            (3, _, 3) => {
+                println!("started");
+                mutex1.lock().unwrap().s.len();
+                mutex2.lock().unwrap().s.len();
+                println!("done");
+            },
+            (_, _, _) => {},
+        };
+
+        let mutex3 = Mutex::new(StateWithField { s: "three".to_owned() });
+        match mutex3.lock().unwrap().s.as_str() {
+            "three" => {
+                println!("started");
+                mutex1.lock().unwrap().s.len();
+                mutex2.lock().unwrap().s.len();
+                println!("done");
+            },
+            _ => {},
+        };
+
+        match (true, mutex3.lock().unwrap().s.as_str()) {
+            (_, "three") => {
+                println!("started");
+                mutex1.lock().unwrap().s.len();
+                mutex2.lock().unwrap().s.len();
+                println!("done");
+            },
+            (_, _) => {},
+        };
+    }
+}
+
+// Should trigger lint when either side of a binary operation creates a temporary with a
+// significant drop.
+// To avoid potential unnecessary copies or creating references that would trigger the significant
+// drop problem, the lint recommends moving the entire binary operation.
+fn should_trigger_lint_for_accessing_field_in_mutex_in_one_side_of_binary_op() {
+    let mutex = Mutex::new(StateWithField { s: "state".to_owned() });
+
+    match mutex.lock().unwrap().s.len() > 1 {
+        true => {
+            mutex.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+
+    match 1 < mutex.lock().unwrap().s.len() {
+        true => {
+            mutex.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+}
+
+// Should trigger lint when both sides of a binary operation creates a temporary with a
+// significant drop.
+// To avoid potential unnecessary copies or creating references that would trigger the significant
+// drop problem, the lint recommends moving the entire binary operation.
+fn should_trigger_lint_for_accessing_fields_in_mutex_in_both_sides_of_binary_op() {
+    let mutex1 = Mutex::new(StateWithField { s: "state".to_owned() });
+    let mutex2 = Mutex::new(StateWithField {
+        s: "statewithfield".to_owned(),
+    });
+
+    match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
+        true => {
+            println!(
+                "{} < {}",
+                mutex1.lock().unwrap().s.len(),
+                mutex2.lock().unwrap().s.len()
+            );
+        },
+        false => {},
+    };
+
+    match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
+        true => {
+            println!(
+                "{} >= {}",
+                mutex1.lock().unwrap().s.len(),
+                mutex2.lock().unwrap().s.len()
+            );
+        },
+        false => {},
+    };
+}
+
+fn should_not_trigger_lint_for_closure_in_scrutinee() {
+    let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
+
+    let get_mutex_guard = || mutex1.lock().unwrap().s.len();
+
+    // Should not trigger lint because the temporary with a significant drop will be dropped
+    // at the end of the closure, so the MutexGuard will be unlocked and not have a potentially
+    // surprising lifetime.
+    match get_mutex_guard() > 1 {
+        true => {
+            mutex1.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+}
+
+fn should_trigger_lint_for_return_from_closure_in_scrutinee() {
+    let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
+
+    let get_mutex_guard = || mutex1.lock().unwrap();
+
+    // Should trigger lint because the temporary with a significant drop is returned from the
+    // closure but not used directly in any match arms, so it has a potentially surprising lifetime.
+    match get_mutex_guard().s.len() > 1 {
+        true => {
+            mutex1.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+}
+
+fn should_trigger_lint_for_return_from_match_in_scrutinee() {
+    let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
+    let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
+
+    let i = 100;
+
+    // Should trigger lint because the nested match within the scrutinee returns a temporary with a
+    // significant drop is but not used directly in any match arms, so it has a potentially
+    // surprising lifetime.
+    match match i {
+        100 => mutex1.lock().unwrap(),
+        _ => mutex2.lock().unwrap(),
+    }
+    .s
+    .len()
+        > 1
+    {
+        true => {
+            mutex1.lock().unwrap().s.len();
+        },
+        false => {
+            println!("nothing to do here");
+        },
+    };
+}
+
+fn should_trigger_lint_for_return_from_if_in_scrutinee() {
+    let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
+    let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
+
+    let i = 100;
+
+    // Should trigger lint because the nested if-expression within the scrutinee returns a temporary
+    // with a significant drop is but not used directly in any match arms, so it has a potentially
+    // surprising lifetime.
+    match if i > 1 {
+        mutex1.lock().unwrap()
+    } else {
+        mutex2.lock().unwrap()
+    }
+    .s
+    .len()
+        > 1
+    {
+        true => {
+            mutex1.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+}
+
+fn should_not_trigger_lint_for_if_in_scrutinee() {
+    let mutex = Mutex::new(StateWithField { s: "state".to_owned() });
+
+    let i = 100;
+
+    // Should not trigger the lint because the temporary with a significant drop *is* dropped within
+    // the body of the if-expression nested within the match scrutinee, and therefore does not have
+    // a potentially surprising lifetime.
+    match if i > 1 {
+        mutex.lock().unwrap().s.len() > 1
+    } else {
+        false
+    } {
+        true => {
+            mutex.lock().unwrap().s.len();
+        },
+        false => {},
+    };
+}
+
+struct StateWithBoxedMutexGuard {
+    u: Mutex<u64>,
+}
+
+impl StateWithBoxedMutexGuard {
+    fn new() -> StateWithBoxedMutexGuard {
+        StateWithBoxedMutexGuard { u: Mutex::new(42) }
+    }
+    fn lock(&self) -> Box<MutexGuard<u64>> {
+        Box::new(self.u.lock().unwrap())
+    }
+}
+
+fn should_trigger_lint_for_boxed_mutex_guard() {
+    let s = StateWithBoxedMutexGuard::new();
+
+    // Should trigger lint because a temporary Box holding a type with a significant drop in a match
+    // scrutinee may have a potentially surprising lifetime.
+    match s.lock().deref().deref() {
+        0 | 1 => println!("Value was less than 2"),
+        _ => println!("Value is {}", s.lock().deref()),
+    };
+}
+
+struct StateStringWithBoxedMutexGuard {
+    s: Mutex<String>,
+}
+
+impl StateStringWithBoxedMutexGuard {
+    fn new() -> StateStringWithBoxedMutexGuard {
+        StateStringWithBoxedMutexGuard {
+            s: Mutex::new("A String".to_owned()),
+        }
+    }
+    fn lock(&self) -> Box<MutexGuard<String>> {
+        Box::new(self.s.lock().unwrap())
+    }
+}
+
+fn should_trigger_lint_for_boxed_mutex_guard_holding_string() {
+    let s = StateStringWithBoxedMutexGuard::new();
+
+    let matcher = String::from("A String");
+
+    // Should trigger lint because a temporary Box holding a type with a significant drop in a match
+    // scrutinee may have a potentially surprising lifetime.
+    match s.lock().deref().deref() {
+        matcher => println!("Value is {}", s.lock().deref()),
+        _ => println!("Value was not a match"),
+    };
+}
+
+struct StateWithIntField {
+    i: u64,
+}
+
+// Should trigger lint when either side of an assign expression contains a temporary with a
+// significant drop, because the temporary's lifetime will be extended to the end of the match.
+// To avoid potential unnecessary copies or creating references that would trigger the significant
+// drop problem, the lint recommends moving the entire binary operation.
+fn should_trigger_lint_in_assign_expr() {
+    let mutex = Mutex::new(StateWithIntField { i: 10 });
+
+    let mut i = 100;
+
+    match mutex.lock().unwrap().i = i {
+        _ => {
+            println!("{}", mutex.lock().unwrap().i);
+        },
+    };
+
+    match i = mutex.lock().unwrap().i {
+        _ => {
+            println!("{}", mutex.lock().unwrap().i);
+        },
+    };
+
+    match mutex.lock().unwrap().i += 1 {
+        _ => {
+            println!("{}", mutex.lock().unwrap().i);
+        },
+    };
+
+    match i += mutex.lock().unwrap().i {
+        _ => {
+            println!("{}", mutex.lock().unwrap().i);
+        },
+    };
+}
+
+#[derive(Debug)]
+enum RecursiveEnum {
+    Foo(Option<Box<RecursiveEnum>>),
+}
+
+#[derive(Debug)]
+enum GenericRecursiveEnum<T> {
+    Foo(T, Option<Box<GenericRecursiveEnum<T>>>),
+}
+
+fn should_not_cause_stack_overflow() {
+    // Test that when a type recursively contains itself, a stack overflow does not occur when
+    // checking sub-types for significant drops.
+    let f = RecursiveEnum::Foo(Some(Box::new(RecursiveEnum::Foo(None))));
+    match f {
+        RecursiveEnum::Foo(Some(f)) => {
+            println!("{:?}", f)
+        },
+        RecursiveEnum::Foo(f) => {
+            println!("{:?}", f)
+        },
+    }
+
+    let f = GenericRecursiveEnum::Foo(1u64, Some(Box::new(GenericRecursiveEnum::Foo(2u64, None))));
+    match f {
+        GenericRecursiveEnum::Foo(i, Some(f)) => {
+            println!("{} {:?}", i, f)
+        },
+        GenericRecursiveEnum::Foo(i, f) => {
+            println!("{} {:?}", i, f)
+        },
+    }
+}
+
+fn main() {}

tests/ui/significant_drop_in_scrutinee.stderr

@@ -0,0 +1,283 @@
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:57:11
+   |
+LL |     match mutex.lock().unwrap().foo() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::significant-drop-in-scrutinee` implied by `-D warnings`
+help: try moving the temporary above the match
+   |
+LL ~     let value = mutex.lock().unwrap().foo();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:130:11
+   |
+LL |     match s.lock_m().get_the_value() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = s.lock_m().get_the_value();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:151:11
+   |
+LL |     match s.lock_m_m().get_the_value() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = s.lock_m_m().get_the_value();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:199:11
+   |
+LL |     match counter.temp_increment().len() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = counter.temp_increment().len();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:222:16
+   |
+LL |         match (mutex1.lock().unwrap().s.len(), true) {
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~         let value = mutex1.lock().unwrap().s.len();
+LL ~         match (value, true) {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:231:22
+   |
+LL |         match (true, mutex1.lock().unwrap().s.len(), true) {
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~         let value = mutex1.lock().unwrap().s.len();
+LL ~         match (true, value, true) {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:241:16
+   |
+LL |         match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~         let value = mutex1.lock().unwrap().s.len();
+LL ~         match (value, true, mutex2.lock().unwrap().s.len()) {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:241:54
+   |
+LL |         match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
+   |                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~         let value = mutex2.lock().unwrap().s.len();
+LL ~         match (mutex1.lock().unwrap().s.len(), true, value) {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:252:15
+   |
+LL |         match mutex3.lock().unwrap().s.as_str() {
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:262:22
+   |
+LL |         match (true, mutex3.lock().unwrap().s.as_str()) {
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:281:11
+   |
+LL |     match mutex.lock().unwrap().s.len() > 1 {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = mutex.lock().unwrap().s.len() > 1;
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:288:11
+   |
+LL |     match 1 < mutex.lock().unwrap().s.len() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = 1 < mutex.lock().unwrap().s.len();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:306:11
+   |
+LL |     match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:317:11
+   |
+LL |     match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:352:11
+   |
+LL |     match get_mutex_guard().s.len() > 1 {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = get_mutex_guard().s.len() > 1;
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:369:11
+   |
+LL |       match match i {
+   |  ___________^
+LL | |         100 => mutex1.lock().unwrap(),
+LL | |         _ => mutex2.lock().unwrap(),
+LL | |     }
+LL | |     .s
+LL | |     .len()
+LL | |         > 1
+   | |___________^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = match i {
+LL +         100 => mutex1.lock().unwrap(),
+LL +         _ => mutex2.lock().unwrap(),
+LL +     }
+LL +     .s
+LL +     .len()
+ ...
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:395:11
+   |
+LL |       match if i > 1 {
+   |  ___________^
+LL | |         mutex1.lock().unwrap()
+LL | |     } else {
+LL | |         mutex2.lock().unwrap()
+...  |
+LL | |     .len()
+LL | |         > 1
+   | |___________^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     let value = if i > 1 {
+LL +         mutex1.lock().unwrap()
+LL +     } else {
+LL +         mutex2.lock().unwrap()
+LL +     }
+LL +     .s
+ ...
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:449:11
+   |
+LL |     match s.lock().deref().deref() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match and create a copy
+   |
+LL ~     let value = *s.lock().deref().deref();
+LL ~     match value {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:477:11
+   |
+LL |     match s.lock().deref().deref() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:496:11
+   |
+LL |     match mutex.lock().unwrap().i = i {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     mutex.lock().unwrap().i = i;
+LL ~     match () {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:502:11
+   |
+LL |     match i = mutex.lock().unwrap().i {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     i = mutex.lock().unwrap().i;
+LL ~     match () {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:508:11
+   |
+LL |     match mutex.lock().unwrap().i += 1 {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     mutex.lock().unwrap().i += 1;
+LL ~     match () {
+   |
+
+error: temporary with significant drop in match scrutinee
+  --> $DIR/significant_drop_in_scrutinee.rs:514:11
+   |
+LL |     match i += mutex.lock().unwrap().i {
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try moving the temporary above the match
+   |
+LL ~     i += mutex.lock().unwrap().i;
+LL ~     match () {
+   |
+
+error: aborting due to 23 previous errors
+

tests/ui/trait_duplication_in_bounds.stderr

@@ -67,13 +67,5 @@ LL |         Self: Iterator<Item = Foo>,
    |
    = help: consider removing this trait bound
 
-error: this trait bound is already specified in the where clause
+error: aborting due to 8 previous errors
-  --> $DIR/trait_duplication_in_bounds.rs:99:23
-   |
-LL | fn impl_trait(_: impl AsRef<str>, _: impl AsRef<str>) {}
-   |                       ^^^^^^^^^^
-   |
-   = help: consider removing this trait bound
-
-error: aborting due to 9 previous errors
 

tests/ui/type_repetition_in_bounds.stderr

@@ -19,13 +19,5 @@ LL |     Self: Copy + Default + Ord,
    |
    = help: consider combining the bounds: `Self: Clone + Copy + Default + Ord`
 
-error: this type has already been used as a bound predicate
+error: aborting due to 2 previous errors
-  --> $DIR/type_repetition_in_bounds.rs:83:43
-   |
-LL | fn impl_trait(_: impl AsRef<str>, _: impl AsRef<str>) {}
-   |                                           ^^^^^^^^^^
-   |
-   = help: consider combining the bounds: `impl AsRef<str>: AsRef<str> + AsRef<str>`
-
-error: aborting due to 3 previous errors