Auto merge of #13050 - Jarcho:misc_small, r=xFrednet

Misc refactorings

Various small re-orderings to check the HIR tree or AST before doing other checks. Also includes a small bug fix for `arc_with_small_send_sync` not actually checking for `Arc::new`.

changelog: none

14 files changed, 98 insertions, 121 deletions

diff --git a/clippy_lints/src/arc_with_non_send_sync.rs b/clippy_lints/src/arc_with_non_send_sync.rs
index d57ab539fff..4eafa330faf 100644
--- a/clippy_lints/src/arc_with_non_send_sync.rs
+++ b/clippy_lints/src/arc_with_non_send_sync.rs
@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::is_from_proc_macro;
 use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
-use clippy_utils::{is_from_proc_macro, last_path_segment};
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::{Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_middle::ty::print::with_forced_trimmed_paths;
@@ -42,12 +42,11 @@ declare_lint_pass!(ArcWithNonSendSync => [ARC_WITH_NON_SEND_SYNC]);
 
 impl<'tcx> LateLintPass<'tcx> for ArcWithNonSendSync {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        if !expr.span.from_expansion()
-            && let ty = cx.typeck_results().expr_ty(expr)
-            && is_type_diagnostic_item(cx, ty, sym::Arc)
-            && let ExprKind::Call(func, [arg]) = expr.kind
-            && let ExprKind::Path(func_path) = func.kind
-            && last_path_segment(&func_path).ident.name == sym::new
+        if let ExprKind::Call(func, [arg]) = expr.kind
+            && let ExprKind::Path(QPath::TypeRelative(func_ty, func_name)) = func.kind
+            && func_name.ident.name == sym::new
+            && !expr.span.from_expansion()
+            && is_type_diagnostic_item(cx, cx.typeck_results().node_type(func_ty.hir_id), sym::Arc)
             && let arg_ty = cx.typeck_results().expr_ty(arg)
             // make sure that the type is not and does not contain any type parameters
             && arg_ty.walk().all(|arg| {
diff --git a/clippy_lints/src/borrow_deref_ref.rs b/clippy_lints/src/borrow_deref_ref.rs
index 0ca4a0e067d..bd123a725a7 100644
--- a/clippy_lints/src/borrow_deref_ref.rs
+++ b/clippy_lints/src/borrow_deref_ref.rs
@@ -49,35 +49,31 @@ declare_lint_pass!(BorrowDerefRef => [BORROW_DEREF_REF]);
 
 impl<'tcx> LateLintPass<'tcx> for BorrowDerefRef {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &rustc_hir::Expr<'tcx>) {
-        if !e.span.from_expansion()
-            && let ExprKind::AddrOf(_, Mutability::Not, addrof_target) = e.kind
-            && !addrof_target.span.from_expansion()
+        if let ExprKind::AddrOf(_, Mutability::Not, addrof_target) = e.kind
             && let ExprKind::Unary(UnOp::Deref, deref_target) = addrof_target.kind
-            && !deref_target.span.from_expansion()
             && !matches!(deref_target.kind, ExprKind::Unary(UnOp::Deref, ..))
+            && !e.span.from_expansion()
+            && !deref_target.span.from_expansion()
+            && !addrof_target.span.from_expansion()
             && let ref_ty = cx.typeck_results().expr_ty(deref_target)
             && let ty::Ref(_, inner_ty, Mutability::Not) = ref_ty.kind()
-        {
-            if let Some(parent_expr) = get_parent_expr(cx, e) {
-                if matches!(parent_expr.kind, ExprKind::Unary(UnOp::Deref, ..))
-                    && !is_lint_allowed(cx, DEREF_ADDROF, parent_expr.hir_id)
-                {
-                    return;
+            && get_parent_expr(cx, e).map_or(true, |parent| {
+                match parent.kind {
+                    // `*&*foo` should lint `deref_addrof` instead.
+                    ExprKind::Unary(UnOp::Deref, _) => is_lint_allowed(cx, DEREF_ADDROF, parent.hir_id),
+                    // `&*foo` creates a distinct temporary from `foo`
+                    ExprKind::AddrOf(_, Mutability::Mut, _) => !matches!(
+                        deref_target.kind,
+                        ExprKind::Path(..)
+                            | ExprKind::Field(..)
+                            | ExprKind::Index(..)
+                            | ExprKind::Unary(UnOp::Deref, ..)
+                    ),
+                    _ => true,
                 }
-
-                // modification to `&mut &*x` is different from `&mut x`
-                if matches!(
-                    deref_target.kind,
-                    ExprKind::Path(..) | ExprKind::Field(..) | ExprKind::Index(..) | ExprKind::Unary(UnOp::Deref, ..)
-                ) && matches!(parent_expr.kind, ExprKind::AddrOf(_, Mutability::Mut, _))
-                {
-                    return;
-                }
-            }
-            if is_from_proc_macro(cx, e) {
-                return;
-            }
-
+            })
+            && !is_from_proc_macro(cx, e)
+        {
             span_lint_and_then(
                 cx,
                 BORROW_DEREF_REF,
diff --git a/clippy_lints/src/collapsible_if.rs b/clippy_lints/src/collapsible_if.rs
index 07b02c98df1..f311c052ad6 100644
--- a/clippy_lints/src/collapsible_if.rs
+++ b/clippy_lints/src/collapsible_if.rs
@@ -93,20 +93,14 @@ declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF, COLLAPSIBLE_ELSE_IF]);
 
 impl EarlyLintPass for CollapsibleIf {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
-        if !expr.span.from_expansion() {
-            check_if(cx, expr);
-        }
-    }
-}
-
-fn check_if(cx: &EarlyContext<'_>, expr: &ast::Expr) {
-    if let ast::ExprKind::If(check, then, else_) = &expr.kind {
-        if let Some(else_) = else_ {
-            check_collapsible_maybe_if_let(cx, then.span, else_);
-        } else if let ast::ExprKind::Let(..) = check.kind {
-            // Prevent triggering on `if let a = b { if c { .. } }`.
-        } else {
-            check_collapsible_no_if_let(cx, expr, check, then);
+        if let ast::ExprKind::If(cond, then, else_) = &expr.kind
+            && !expr.span.from_expansion()
+        {
+            if let Some(else_) = else_ {
+                check_collapsible_maybe_if_let(cx, then.span, else_);
+            } else if !matches!(cond.kind, ast::ExprKind::Let(..)) {
+                check_collapsible_no_if_let(cx, expr, cond, then);
+            }
         }
     }
 }
@@ -189,13 +183,10 @@ fn check_collapsible_no_if_let(cx: &EarlyContext<'_>, expr: &ast::Expr, check: &
 
 /// If the block contains only one expression, return it.
 fn expr_block(block: &ast::Block) -> Option<&ast::Expr> {
-    let mut it = block.stmts.iter();
-
-    if let (Some(stmt), None) = (it.next(), it.next()) {
-        match stmt.kind {
-            ast::StmtKind::Expr(ref expr) | ast::StmtKind::Semi(ref expr) => Some(expr),
-            _ => None,
-        }
+    if let [stmt] = &*block.stmts
+        && let ast::StmtKind::Expr(expr) | ast::StmtKind::Semi(expr) = &stmt.kind
+    {
+        Some(expr)
     } else {
         None
     }
diff --git a/clippy_lints/src/collection_is_never_read.rs b/clippy_lints/src/collection_is_never_read.rs
index 28d9f68d504..eebda3ff76f 100644
--- a/clippy_lints/src/collection_is_never_read.rs
+++ b/clippy_lints/src/collection_is_never_read.rs
@@ -59,9 +59,9 @@ static COLLECTIONS: [Symbol; 9] = [
 
 impl<'tcx> LateLintPass<'tcx> for CollectionIsNeverRead {
     fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx LetStmt<'tcx>) {
-        // Look for local variables whose type is a container. Search surrounding bock for read access.
-        if match_acceptable_type(cx, local, &COLLECTIONS)
-            && let PatKind::Binding(_, local_id, _, _) = local.pat.kind
+        // Look for local variables whose type is a container. Search surrounding block for read access.
+        if let PatKind::Binding(_, local_id, _, _) = local.pat.kind
+            && match_acceptable_type(cx, local, &COLLECTIONS)
             && let Some(enclosing_block) = get_enclosing_block(cx, local.hir_id)
             && has_no_read_access(cx, local_id, enclosing_block)
         {
diff --git a/clippy_lints/src/crate_in_macro_def.rs b/clippy_lints/src/crate_in_macro_def.rs
index adf6f7c4737..678bdbc0ffb 100644
--- a/clippy_lints/src/crate_in_macro_def.rs
+++ b/clippy_lints/src/crate_in_macro_def.rs
@@ -53,10 +53,9 @@ declare_lint_pass!(CrateInMacroDef => [CRATE_IN_MACRO_DEF]);
 
 impl EarlyLintPass for CrateInMacroDef {
     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
-        if item.attrs.iter().any(is_macro_export)
-            && let ItemKind::MacroDef(macro_def) = &item.kind
-            && let tts = macro_def.body.tokens.clone()
-            && let Some(span) = contains_unhygienic_crate_reference(&tts)
+        if let ItemKind::MacroDef(macro_def) = &item.kind
+            && item.attrs.iter().any(is_macro_export)
+            && let Some(span) = contains_unhygienic_crate_reference(&macro_def.body.tokens)
         {
             span_lint_and_sugg(
                 cx,
diff --git a/clippy_lints/src/else_if_without_else.rs b/clippy_lints/src/else_if_without_else.rs
index bb6f9aac223..7a6dc469727 100644
--- a/clippy_lints/src/else_if_without_else.rs
+++ b/clippy_lints/src/else_if_without_else.rs
@@ -50,12 +50,9 @@ declare_lint_pass!(ElseIfWithoutElse => [ELSE_IF_WITHOUT_ELSE]);
 
 impl EarlyLintPass for ElseIfWithoutElse {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, item: &Expr) {
-        if in_external_macro(cx.sess(), item.span) {
-            return;
-        }
-
         if let ExprKind::If(_, _, Some(ref els)) = item.kind
             && let ExprKind::If(_, _, None) = els.kind
+            && !in_external_macro(cx.sess(), item.span)
         {
             span_lint_and_help(
                 cx,
diff --git a/clippy_lints/src/empty_enum.rs b/clippy_lints/src/empty_enum.rs
index d16714695cb..1869faab1d3 100644
--- a/clippy_lints/src/empty_enum.rs
+++ b/clippy_lints/src/empty_enum.rs
@@ -64,25 +64,21 @@ declare_lint_pass!(EmptyEnum => [EMPTY_ENUM]);
 
 impl<'tcx> LateLintPass<'tcx> for EmptyEnum {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
-        // Only suggest the `never_type` if the feature is enabled
-        if !cx.tcx.features().never_type {
-            return;
-        }
-
-        if let ItemKind::Enum(..) = item.kind {
-            let ty = cx.tcx.type_of(item.owner_id).instantiate_identity();
-            let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
-            if adt.variants().is_empty() {
-                span_lint_and_help(
-                    cx,
-                    EMPTY_ENUM,
-                    item.span,
-                    "enum with no variants",
-                    None,
-                    "consider using the uninhabited type `!` (never type) or a wrapper \
-                    around it to introduce a type which can't be instantiated",
-                );
-            }
+        if let ItemKind::Enum(..) = item.kind
+            // Only suggest the `never_type` if the feature is enabled
+            && cx.tcx.features().never_type
+            && let Some(adt) = cx.tcx.type_of(item.owner_id).instantiate_identity().ty_adt_def()
+            && adt.variants().is_empty()
+        {
+            span_lint_and_help(
+                cx,
+                EMPTY_ENUM,
+                item.span,
+                "enum with no variants",
+                None,
+                "consider using the uninhabited type `!` (never type) or a wrapper \
+                around it to introduce a type which can't be instantiated",
+            );
         }
     }
 }
diff --git a/clippy_lints/src/equatable_if_let.rs b/clippy_lints/src/equatable_if_let.rs
index 37442bf3e28..fb9f2b1526e 100644
--- a/clippy_lints/src/equatable_if_let.rs
+++ b/clippy_lints/src/equatable_if_let.rs
@@ -70,9 +70,9 @@ fn is_structural_partial_eq<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, other: T
 
 impl<'tcx> LateLintPass<'tcx> for PatternEquality {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        if !in_external_macro(cx.sess(), expr.span)
-            && let ExprKind::Let(let_expr) = expr.kind
+        if let ExprKind::Let(let_expr) = expr.kind
             && unary_pattern(let_expr.pat)
+            && !in_external_macro(cx.sess(), expr.span)
         {
             let exp_ty = cx.typeck_results().expr_ty(let_expr.init);
             let pat_ty = cx.typeck_results().pat_ty(let_expr.pat);
diff --git a/clippy_lints/src/error_impl_error.rs b/clippy_lints/src/error_impl_error.rs
index 8e49138cd26..1e6447dc253 100644
--- a/clippy_lints/src/error_impl_error.rs
+++ b/clippy_lints/src/error_impl_error.rs
@@ -36,15 +36,12 @@ declare_lint_pass!(ErrorImplError => [ERROR_IMPL_ERROR]);
 
 impl<'tcx> LateLintPass<'tcx> for ErrorImplError {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
-        let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error) else {
-            return;
-        };
-
         match item.kind {
             ItemKind::TyAlias(..)
                 if item.ident.name == sym::Error
                     && is_visible_outside_module(cx, item.owner_id.def_id)
                     && let ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
+                    && let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error)
                     && implements_trait(cx, ty, error_def_id, &[]) =>
             {
                 span_lint(
@@ -56,9 +53,9 @@ impl<'tcx> LateLintPass<'tcx> for ErrorImplError {
             },
             ItemKind::Impl(imp)
                 if let Some(trait_def_id) = imp.of_trait.and_then(|t| t.trait_def_id())
+                    && let Some(error_def_id) = cx.tcx.get_diagnostic_item(sym::Error)
                     && error_def_id == trait_def_id
                     && let Some(def_id) = path_res(cx, imp.self_ty).opt_def_id().and_then(DefId::as_local)
-                    && let hir_id = cx.tcx.local_def_id_to_hir_id(def_id)
                     && let Some(ident) = cx.tcx.opt_item_ident(def_id.to_def_id())
                     && ident.name == sym::Error
                     && is_visible_outside_module(cx, def_id) =>
@@ -66,7 +63,7 @@ impl<'tcx> LateLintPass<'tcx> for ErrorImplError {
                 span_lint_hir_and_then(
                     cx,
                     ERROR_IMPL_ERROR,
-                    hir_id,
+                    cx.tcx.local_def_id_to_hir_id(def_id),
                     ident.span,
                     "exported type named `Error` that implements `Error`",
                     |diag| {
diff --git a/clippy_lints/src/exhaustive_items.rs b/clippy_lints/src/exhaustive_items.rs
index 436dc8611bd..0f4176ec73b 100644
--- a/clippy_lints/src/exhaustive_items.rs
+++ b/clippy_lints/src/exhaustive_items.rs
@@ -70,20 +70,24 @@ declare_lint_pass!(ExhaustiveItems => [EXHAUSTIVE_ENUMS, EXHAUSTIVE_STRUCTS]);
 
 impl LateLintPass<'_> for ExhaustiveItems {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
-        if let ItemKind::Enum(..) | ItemKind::Struct(..) = item.kind
-            && cx.effective_visibilities.is_exported(item.owner_id.def_id)
+        let (lint, msg, fields) = match item.kind {
+            ItemKind::Enum(..) => (
+                EXHAUSTIVE_ENUMS,
+                "exported enums should not be exhaustive",
+                [].as_slice(),
+            ),
+            ItemKind::Struct(v, ..) => (
+                EXHAUSTIVE_STRUCTS,
+                "exported structs should not be exhaustive",
+                v.fields(),
+            ),
+            _ => return,
+        };
+        if cx.effective_visibilities.is_exported(item.owner_id.def_id)
             && let attrs = cx.tcx.hir().attrs(item.hir_id())
             && !attrs.iter().any(|a| a.has_name(sym::non_exhaustive))
+            && fields.iter().all(|f| cx.tcx.visibility(f.def_id).is_public())
         {
-            let (lint, msg) = if let ItemKind::Struct(ref v, ..) = item.kind {
-                if v.fields().iter().any(|f| !cx.tcx.visibility(f.def_id).is_public()) {
-                    // skip structs with private fields
-                    return;
-                }
-                (EXHAUSTIVE_STRUCTS, "exported structs should not be exhaustive")
-            } else {
-                (EXHAUSTIVE_ENUMS, "exported enums should not be exhaustive")
-            };
             let suggestion_span = item.span.shrink_to_lo();
             let indent = " ".repeat(indent_of(cx, item.span).unwrap_or(0));
             span_lint_and_then(cx, lint, item.span, msg, |diag| {
diff --git a/clippy_lints/src/exit.rs b/clippy_lints/src/exit.rs
index 91c94d66458..f37d11f7eb9 100644
--- a/clippy_lints/src/exit.rs
+++ b/clippy_lints/src/exit.rs
@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::is_entrypoint_fn;
-use rustc_hir::{Expr, ExprKind, Item, ItemKind, Node};
+use rustc_hir::{Expr, ExprKind, Item, ItemKind, OwnerNode};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::sym;
@@ -47,8 +47,8 @@ impl<'tcx> LateLintPass<'tcx> for Exit {
             && let ExprKind::Path(ref path) = path_expr.kind
             && let Some(def_id) = cx.qpath_res(path, path_expr.hir_id).opt_def_id()
             && cx.tcx.is_diagnostic_item(sym::process_exit, def_id)
-            && let parent = cx.tcx.hir().get_parent_item(e.hir_id).def_id
-            && let Node::Item(Item{kind: ItemKind::Fn(..), ..}) = cx.tcx.hir_node_by_def_id(parent)
+            && let parent = cx.tcx.hir().get_parent_item(e.hir_id)
+            && let OwnerNode::Item(Item{kind: ItemKind::Fn(..), ..}) = cx.tcx.hir_owner_node(parent)
             // If the next item up is a function we check if it is an entry point
             // and only then emit a linter warning
             && !is_entrypoint_fn(cx, parent.to_def_id())
diff --git a/clippy_lints/src/float_literal.rs b/clippy_lints/src/float_literal.rs
index 2261fcdbdab..6adcd2235dc 100644
--- a/clippy_lints/src/float_literal.rs
+++ b/clippy_lints/src/float_literal.rs
@@ -62,10 +62,9 @@ declare_lint_pass!(FloatLiteral => [EXCESSIVE_PRECISION, LOSSY_FLOAT_LITERAL]);
 
 impl<'tcx> LateLintPass<'tcx> for FloatLiteral {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
-        let ty = cx.typeck_results().expr_ty(expr);
-        if let ty::Float(fty) = *ty.kind()
-            && let hir::ExprKind::Lit(lit) = expr.kind
+        if let hir::ExprKind::Lit(lit) = expr.kind
             && let LitKind::Float(sym, lit_float_ty) = lit.node
+            && let ty::Float(fty) = *cx.typeck_results().expr_ty(expr).kind()
         {
             let sym_str = sym.as_str();
             let formatter = FloatFormat::new(sym_str);
diff --git a/clippy_lints/src/from_over_into.rs b/clippy_lints/src/from_over_into.rs
index 150e9adf363..b6c8437fb8f 100644
--- a/clippy_lints/src/from_over_into.rs
+++ b/clippy_lints/src/from_over_into.rs
@@ -66,10 +66,6 @@ impl_lint_pass!(FromOverInto => [FROM_OVER_INTO]);
 
 impl<'tcx> LateLintPass<'tcx> for FromOverInto {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
-        if !self.msrv.meets(msrvs::RE_REBALANCING_COHERENCE) || !span_is_local(item.span) {
-            return;
-        }
-
         if let ItemKind::Impl(Impl {
             of_trait: Some(hir_trait_ref),
             self_ty,
@@ -79,6 +75,8 @@ impl<'tcx> LateLintPass<'tcx> for FromOverInto {
             && let Some(into_trait_seg) = hir_trait_ref.path.segments.last()
             // `impl Into<target_ty> for self_ty`
             && let Some(GenericArgs { args: [GenericArg::Type(target_ty)], .. }) = into_trait_seg.args
+            && self.msrv.meets(msrvs::RE_REBALANCING_COHERENCE)
+            && span_is_local(item.span)
             && let Some(middle_trait_ref) = cx.tcx.impl_trait_ref(item.owner_id)
                                                   .map(ty::EarlyBinder::instantiate_identity)
             && cx.tcx.is_diagnostic_item(sym::Into, middle_trait_ref.def_id)
diff --git a/clippy_lints/src/from_str_radix_10.rs b/clippy_lints/src/from_str_radix_10.rs
index 82ce501bac5..9acb72b2e37 100644
--- a/clippy_lints/src/from_str_radix_10.rs
+++ b/clippy_lints/src/from_str_radix_10.rs
@@ -47,9 +47,13 @@ impl<'tcx> LateLintPass<'tcx> for FromStrRadix10 {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, exp: &Expr<'tcx>) {
         if let ExprKind::Call(maybe_path, [src, radix]) = &exp.kind
             && let ExprKind::Path(QPath::TypeRelative(ty, pathseg)) = &maybe_path.kind
-            // do not lint in constant context, because the suggestion won't work.
-            // NB: keep this check until a new `const_trait_impl` is available and stablized.
-            && !in_constant(cx, exp.hir_id)
+
+            // check if the second argument is a primitive `10`
+            && is_integer_literal(radix, 10)
+
+            // check if the second part of the path indeed calls the associated
+            // function `from_str_radix`
+            && pathseg.ident.name.as_str() == "from_str_radix"
 
             // check if the first part of the path is some integer primitive
             && let TyKind::Path(ty_qpath) = &ty.kind
@@ -57,12 +61,9 @@ impl<'tcx> LateLintPass<'tcx> for FromStrRadix10 {
             && let def::Res::PrimTy(prim_ty) = ty_res
             && matches!(prim_ty, PrimTy::Int(_) | PrimTy::Uint(_))
 
-            // check if the second part of the path indeed calls the associated
-            // function `from_str_radix`
-            && pathseg.ident.name.as_str() == "from_str_radix"
-
-            // check if the second argument is a primitive `10`
-            && is_integer_literal(radix, 10)
+            // do not lint in constant context, because the suggestion won't work.
+            // NB: keep this check until a new `const_trait_impl` is available and stablized.
+            && !in_constant(cx, exp.hir_id)
         {
             let expr = if let ExprKind::AddrOf(_, _, expr) = &src.kind {
                 let ty = cx.typeck_results().expr_ty(expr);