Convert `&Option<T>` to `Option<&T>`

7 files changed, 122 insertions, 83 deletions

diff --git a/clippy_lints/src/cargo/common_metadata.rs b/clippy_lints/src/cargo/common_metadata.rs
index fed0aa8b275..6714c053913 100644
--- a/clippy_lints/src/cargo/common_metadata.rs
+++ b/clippy_lints/src/cargo/common_metadata.rs
@@ -10,27 +10,27 @@ pub(super) fn check(cx: &LateContext<'_>, metadata: &Metadata, ignore_publish: b
         // only run the lint if publish is `None` (`publish = true` or skipped entirely)
         // or if the vector isn't empty (`publish = ["something"]`)
         if package.publish.as_ref().filter(|publish| publish.is_empty()).is_none() || ignore_publish {
-            if is_empty_str(&package.description) {
+            if is_empty_str(package.description.as_ref()) {
                 missing_warning(cx, package, "package.description");
             }
 
-            if is_empty_str(&package.license) && is_empty_str(&package.license_file) {
+            if is_empty_str(package.license.as_ref()) && is_empty_str(package.license_file.as_ref()) {
                 missing_warning(cx, package, "either package.license or package.license_file");
             }
 
-            if is_empty_str(&package.repository) {
+            if is_empty_str(package.repository.as_ref()) {
                 missing_warning(cx, package, "package.repository");
             }
 
-            if is_empty_str(&package.readme) {
+            if is_empty_str(package.readme.as_ref()) {
                 missing_warning(cx, package, "package.readme");
             }
 
-            if is_empty_vec(&package.keywords) {
+            if is_empty_vec(package.keywords.as_ref()) {
                 missing_warning(cx, package, "package.keywords");
             }
 
-            if is_empty_vec(&package.categories) {
+            if is_empty_vec(package.categories.as_ref()) {
                 missing_warning(cx, package, "package.categories");
             }
         }
@@ -42,8 +42,8 @@ fn missing_warning(cx: &LateContext<'_>, package: &cargo_metadata::Package, fiel
     span_lint(cx, CARGO_COMMON_METADATA, DUMMY_SP, message);
 }
 
-fn is_empty_str<T: AsRef<std::ffi::OsStr>>(value: &Option<T>) -> bool {
-    value.as_ref().map_or(true, |s| s.as_ref().is_empty())
+fn is_empty_str<T: AsRef<std::ffi::OsStr>>(value: Option<&T>) -> bool {
+    value.map_or(true, |s| s.as_ref().is_empty())
 }
 
 fn is_empty_vec(value: &[String]) -> bool {
diff --git a/clippy_lints/src/functions/mod.rs b/clippy_lints/src/functions/mod.rs
index 203c3ce9eec..91d73c2a9c9 100644
--- a/clippy_lints/src/functions/mod.rs
+++ b/clippy_lints/src/functions/mod.rs
@@ -443,7 +443,7 @@ declare_clippy_lint! {
     /// ```
     #[clippy::version = "1.82.0"]
     pub REF_OPTION,
-    nursery,
+    pedantic,
     "function signature uses `&Option<T>` instead of `Option<&T>`"
 }
 
diff --git a/clippy_lints/src/unnested_or_patterns.rs b/clippy_lints/src/unnested_or_patterns.rs
index 104be63bb15..c7c837de505 100644
--- a/clippy_lints/src/unnested_or_patterns.rs
+++ b/clippy_lints/src/unnested_or_patterns.rs
@@ -275,12 +275,15 @@ fn transform_with_focus_on_idx(alternatives: &mut ThinVec<P<Pat>>, focus_idx: us
             |k, ps1, idx| matches!(
                 k,
                 TupleStruct(qself2, path2, ps2)
-                    if eq_maybe_qself(qself1, qself2) && eq_path(path1, path2) && eq_pre_post(ps1, ps2, idx)
+                    if eq_maybe_qself(qself1.as_ref(), qself2.as_ref())
+                       && eq_path(path1, path2) && eq_pre_post(ps1, ps2, idx)
             ),
             |k| always_pat!(k, TupleStruct(_, _, ps) => ps),
         ),
         // Transform a record pattern `S { fp_0, ..., fp_n }`.
-        Struct(qself1, path1, fps1, rest1) => extend_with_struct_pat(qself1, path1, fps1, *rest1, start, alternatives),
+        Struct(qself1, path1, fps1, rest1) => {
+            extend_with_struct_pat(qself1.as_ref(), path1, fps1, *rest1, start, alternatives)
+        },
     };
 
     alternatives[focus_idx].kind = focus_kind;
@@ -292,7 +295,7 @@ fn transform_with_focus_on_idx(alternatives: &mut ThinVec<P<Pat>>, focus_idx: us
 /// So when we fixate on some `ident_k: pat_k`, we try to find `ident_k` in the other pattern
 /// and check that all `fp_i` where `i ∈ ((0...n) \ k)` between two patterns are equal.
 fn extend_with_struct_pat(
-    qself1: &Option<P<ast::QSelf>>,
+    qself1: Option<&P<ast::QSelf>>,
     path1: &ast::Path,
     fps1: &mut [ast::PatField],
     rest1: ast::PatFieldsRest,
@@ -307,7 +310,7 @@ fn extend_with_struct_pat(
             |k| {
                 matches!(k, Struct(qself2, path2, fps2, rest2)
                 if rest1 == *rest2 // If one struct pattern has `..` so must the other.
-                && eq_maybe_qself(qself1, qself2)
+                && eq_maybe_qself(qself1, qself2.as_ref())
                 && eq_path(path1, path2)
                 && fps1.len() == fps2.len()
                 && fps1.iter().enumerate().all(|(idx_1, fp1)| {
diff --git a/clippy_utils/src/ast_utils.rs b/clippy_utils/src/ast_utils.rs
index 49323492e12..68f74e52ed7 100644
--- a/clippy_utils/src/ast_utils.rs
+++ b/clippy_utils/src/ast_utils.rs
@@ -37,20 +37,27 @@ pub fn eq_pat(l: &Pat, r: &Pat) -> bool {
         (_, Paren(r)) => eq_pat(l, r),
         (Wild, Wild) | (Rest, Rest) => true,
         (Lit(l), Lit(r)) => eq_expr(l, r),
-        (Ident(b1, i1, s1), Ident(b2, i2, s2)) => b1 == b2 && eq_id(*i1, *i2) && both(s1, s2, |l, r| eq_pat(l, r)),
+        (Ident(b1, i1, s1), Ident(b2, i2, s2)) => {
+            b1 == b2 && eq_id(*i1, *i2) && both(s1.as_deref(), s2.as_deref(), eq_pat)
+        },
         (Range(lf, lt, le), Range(rf, rt, re)) => {
-            eq_expr_opt(lf, rf) && eq_expr_opt(lt, rt) && eq_range_end(&le.node, &re.node)
+            eq_expr_opt(lf.as_ref(), rf.as_ref())
+                && eq_expr_opt(lt.as_ref(), rt.as_ref())
+                && eq_range_end(&le.node, &re.node)
         },
         (Box(l), Box(r))
         | (Ref(l, Mutability::Not), Ref(r, Mutability::Not))
         | (Ref(l, Mutability::Mut), Ref(r, Mutability::Mut)) => eq_pat(l, r),
         (Tuple(l), Tuple(r)) | (Slice(l), Slice(r)) => over(l, r, |l, r| eq_pat(l, r)),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
+        (Path(lq, lp), Path(rq, rp)) => both(lq.as_ref(), rq.as_ref(), eq_qself) && eq_path(lp, rp),
         (TupleStruct(lqself, lp, lfs), TupleStruct(rqself, rp, rfs)) => {
-            eq_maybe_qself(lqself, rqself) && eq_path(lp, rp) && over(lfs, rfs, |l, r| eq_pat(l, r))
+            eq_maybe_qself(lqself.as_ref(), rqself.as_ref()) && eq_path(lp, rp) && over(lfs, rfs, |l, r| eq_pat(l, r))
         },
         (Struct(lqself, lp, lfs, lr), Struct(rqself, rp, rfs, rr)) => {
-            lr == rr && eq_maybe_qself(lqself, rqself) && eq_path(lp, rp) && unordered_over(lfs, rfs, eq_field_pat)
+            lr == rr
+                && eq_maybe_qself(lqself.as_ref(), rqself.as_ref())
+                && eq_path(lp, rp)
+                && unordered_over(lfs, rfs, eq_field_pat)
         },
         (Or(ls), Or(rs)) => unordered_over(ls, rs, |l, r| eq_pat(l, r)),
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
@@ -79,7 +86,7 @@ pub fn eq_qself(l: &P<QSelf>, r: &P<QSelf>) -> bool {
     l.position == r.position && eq_ty(&l.ty, &r.ty)
 }
 
-pub fn eq_maybe_qself(l: &Option<P<QSelf>>, r: &Option<P<QSelf>>) -> bool {
+pub fn eq_maybe_qself(l: Option<&P<QSelf>>, r: Option<&P<QSelf>>) -> bool {
     match (l, r) {
         (Some(l), Some(r)) => eq_qself(l, r),
         (None, None) => true,
@@ -92,7 +99,7 @@ pub fn eq_path(l: &Path, r: &Path) -> bool {
 }
 
 pub fn eq_path_seg(l: &PathSegment, r: &PathSegment) -> bool {
-    eq_id(l.ident, r.ident) && both(&l.args, &r.args, |l, r| eq_generic_args(l, r))
+    eq_id(l.ident, r.ident) && both(l.args.as_ref(), r.args.as_ref(), |l, r| eq_generic_args(l, r))
 }
 
 pub fn eq_generic_args(l: &GenericArgs, r: &GenericArgs) -> bool {
@@ -122,7 +129,7 @@ pub fn eq_generic_arg(l: &GenericArg, r: &GenericArg) -> bool {
     }
 }
 
-pub fn eq_expr_opt(l: &Option<P<Expr>>, r: &Option<P<Expr>>) -> bool {
+pub fn eq_expr_opt(l: Option<&P<Expr>>, r: Option<&P<Expr>>) -> bool {
     both(l, r, |l, r| eq_expr(l, r))
 }
 
@@ -169,8 +176,12 @@ pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
         (Lit(l), Lit(r)) => l == r,
         (Cast(l, lt), Cast(r, rt)) | (Type(l, lt), Type(r, rt)) => eq_expr(l, r) && eq_ty(lt, rt),
         (Let(lp, le, _, _), Let(rp, re, _, _)) => eq_pat(lp, rp) && eq_expr(le, re),
-        (If(lc, lt, le), If(rc, rt, re)) => eq_expr(lc, rc) && eq_block(lt, rt) && eq_expr_opt(le, re),
-        (While(lc, lt, ll), While(rc, rt, rl)) => eq_label(ll, rl) && eq_expr(lc, rc) && eq_block(lt, rt),
+        (If(lc, lt, le), If(rc, rt, re)) => {
+            eq_expr(lc, rc) && eq_block(lt, rt) && eq_expr_opt(le.as_ref(), re.as_ref())
+        },
+        (While(lc, lt, ll), While(rc, rt, rl)) => {
+            eq_label(ll.as_ref(), rl.as_ref()) && eq_expr(lc, rc) && eq_block(lt, rt)
+        },
         (
             ForLoop {
                 pat: lp,
@@ -186,13 +197,13 @@ pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
                 label: rl,
                 kind: rk,
             },
-        ) => eq_label(ll, rl) && eq_pat(lp, rp) && eq_expr(li, ri) && eq_block(lt, rt) && lk == rk,
-        (Loop(lt, ll, _), Loop(rt, rl, _)) => eq_label(ll, rl) && eq_block(lt, rt),
-        (Block(lb, ll), Block(rb, rl)) => eq_label(ll, rl) && eq_block(lb, rb),
+        ) => eq_label(ll.as_ref(), rl.as_ref()) && eq_pat(lp, rp) && eq_expr(li, ri) && eq_block(lt, rt) && lk == rk,
+        (Loop(lt, ll, _), Loop(rt, rl, _)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_block(lt, rt),
+        (Block(lb, ll), Block(rb, rl)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_block(lb, rb),
         (TryBlock(l), TryBlock(r)) => eq_block(l, r),
-        (Yield(l), Yield(r)) | (Ret(l), Ret(r)) => eq_expr_opt(l, r),
-        (Break(ll, le), Break(rl, re)) => eq_label(ll, rl) && eq_expr_opt(le, re),
-        (Continue(ll), Continue(rl)) => eq_label(ll, rl),
+        (Yield(l), Yield(r)) | (Ret(l), Ret(r)) => eq_expr_opt(l.as_ref(), r.as_ref()),
+        (Break(ll, le), Break(rl, re)) => eq_label(ll.as_ref(), rl.as_ref()) && eq_expr_opt(le.as_ref(), re.as_ref()),
+        (Continue(ll), Continue(rl)) => eq_label(ll.as_ref(), rl.as_ref()),
         (Assign(l1, l2, _), Assign(r1, r2, _)) | (Index(l1, l2, _), Index(r1, r2, _)) => {
             eq_expr(l1, r1) && eq_expr(l2, r2)
         },
@@ -227,12 +238,14 @@ pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
                 && eq_expr(le, re)
         },
         (Gen(lc, lb, lk, _), Gen(rc, rb, rk, _)) => lc == rc && eq_block(lb, rb) && lk == rk,
-        (Range(lf, lt, ll), Range(rf, rt, rl)) => ll == rl && eq_expr_opt(lf, rf) && eq_expr_opt(lt, rt),
+        (Range(lf, lt, ll), Range(rf, rt, rl)) => {
+            ll == rl && eq_expr_opt(lf.as_ref(), rf.as_ref()) && eq_expr_opt(lt.as_ref(), rt.as_ref())
+        },
         (AddrOf(lbk, lm, le), AddrOf(rbk, rm, re)) => lbk == rbk && lm == rm && eq_expr(le, re),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
+        (Path(lq, lp), Path(rq, rp)) => both(lq.as_ref(), rq.as_ref(), eq_qself) && eq_path(lp, rp),
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
         (Struct(lse), Struct(rse)) => {
-            eq_maybe_qself(&lse.qself, &rse.qself)
+            eq_maybe_qself(lse.qself.as_ref(), rse.qself.as_ref())
                 && eq_path(&lse.path, &rse.path)
                 && eq_struct_rest(&lse.rest, &rse.rest)
                 && unordered_over(&lse.fields, &rse.fields, eq_field)
@@ -264,12 +277,12 @@ pub fn eq_field(l: &ExprField, r: &ExprField) -> bool {
 pub fn eq_arm(l: &Arm, r: &Arm) -> bool {
     l.is_placeholder == r.is_placeholder
         && eq_pat(&l.pat, &r.pat)
-        && eq_expr_opt(&l.body, &r.body)
-        && eq_expr_opt(&l.guard, &r.guard)
+        && eq_expr_opt(l.body.as_ref(), r.body.as_ref())
+        && eq_expr_opt(l.guard.as_ref(), r.guard.as_ref())
         && over(&l.attrs, &r.attrs, eq_attr)
 }
 
-pub fn eq_label(l: &Option<Label>, r: &Option<Label>) -> bool {
+pub fn eq_label(l: Option<&Label>, r: Option<&Label>) -> bool {
     both(l, r, |l, r| eq_id(l.ident, r.ident))
 }
 
@@ -282,7 +295,7 @@ pub fn eq_stmt(l: &Stmt, r: &Stmt) -> bool {
     match (&l.kind, &r.kind) {
         (Let(l), Let(r)) => {
             eq_pat(&l.pat, &r.pat)
-                && both(&l.ty, &r.ty, |l, r| eq_ty(l, r))
+                && both(l.ty.as_ref(), r.ty.as_ref(), |l, r| eq_ty(l, r))
                 && eq_local_kind(&l.kind, &r.kind)
                 && over(&l.attrs, &r.attrs, eq_attr)
         },
@@ -329,7 +342,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 expr: re,
                 safety: rs,
             }),
-        ) => lm == rm && ls == rs && eq_ty(lt, rt) && eq_expr_opt(le, re),
+        ) => lm == rm && ls == rs && eq_ty(lt, rt) && eq_expr_opt(le.as_ref(), re.as_ref()),
         (
             Const(box ConstItem {
                 defaultness: ld,
@@ -343,7 +356,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 ty: rt,
                 expr: re,
             }),
-        ) => eq_defaultness(*ld, *rd) && eq_generics(lg, rg) && eq_ty(lt, rt) && eq_expr_opt(le, re),
+        ) => eq_defaultness(*ld, *rd) && eq_generics(lg, rg) && eq_ty(lt, rt) && eq_expr_opt(le.as_ref(), re.as_ref()),
         (
             Fn(box ast::Fn {
                 defaultness: ld,
@@ -358,7 +371,10 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 body: rb,
             }),
         ) => {
-            eq_defaultness(*ld, *rd) && eq_fn_sig(lf, rf) && eq_generics(lg, rg) && both(lb, rb, |l, r| eq_block(l, r))
+            eq_defaultness(*ld, *rd)
+                && eq_fn_sig(lf, rf)
+                && eq_generics(lg, rg)
+                && both(lb.as_ref(), rb.as_ref(), |l, r| eq_block(l, r))
         },
         (Mod(lu, lmk), Mod(ru, rmk)) => {
             lu == ru
@@ -371,7 +387,8 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 }
         },
         (ForeignMod(l), ForeignMod(r)) => {
-            both(&l.abi, &r.abi, eq_str_lit) && over(&l.items, &r.items, |l, r| eq_item(l, r, eq_foreign_item_kind))
+            both(l.abi.as_ref(), r.abi.as_ref(), eq_str_lit)
+                && over(&l.items, &r.items, |l, r| eq_item(l, r, eq_foreign_item_kind))
         },
         (
             TyAlias(box ast::TyAlias {
@@ -392,7 +409,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
                 && over(lb, rb, eq_generic_bound)
-                && both(lt, rt, |l, r| eq_ty(l, r))
+                && both(lt.as_ref(), rt.as_ref(), |l, r| eq_ty(l, r))
         },
         (Enum(le, lg), Enum(re, rg)) => over(&le.variants, &re.variants, eq_variant) && eq_generics(lg, rg),
         (Struct(lv, lg), Struct(rv, rg)) | (Union(lv, lg), Union(rv, rg)) => {
@@ -448,7 +465,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 && eq_defaultness(*ld, *rd)
                 && matches!(lc, ast::Const::No) == matches!(rc, ast::Const::No)
                 && eq_generics(lg, rg)
-                && both(lot, rot, |l, r| eq_path(&l.path, &r.path))
+                && both(lot.as_ref(), rot.as_ref(), |l, r| eq_path(&l.path, &r.path))
                 && eq_ty(lst, rst)
                 && over(li, ri, |l, r| eq_item(l, r, eq_assoc_item_kind))
         },
@@ -474,7 +491,7 @@ pub fn eq_foreign_item_kind(l: &ForeignItemKind, r: &ForeignItemKind) -> bool {
                 expr: re,
                 safety: rs,
             }),
-        ) => lm == rm && eq_ty(lt, rt) && eq_expr_opt(le, re) && ls == rs,
+        ) => lm == rm && eq_ty(lt, rt) && eq_expr_opt(le.as_ref(), re.as_ref()) && ls == rs,
         (
             Fn(box ast::Fn {
                 defaultness: ld,
@@ -489,7 +506,10 @@ pub fn eq_foreign_item_kind(l: &ForeignItemKind, r: &ForeignItemKind) -> bool {
                 body: rb,
             }),
         ) => {
-            eq_defaultness(*ld, *rd) && eq_fn_sig(lf, rf) && eq_generics(lg, rg) && both(lb, rb, |l, r| eq_block(l, r))
+            eq_defaultness(*ld, *rd)
+                && eq_fn_sig(lf, rf)
+                && eq_generics(lg, rg)
+                && both(lb.as_ref(), rb.as_ref(), |l, r| eq_block(l, r))
         },
         (
             TyAlias(box ast::TyAlias {
@@ -510,7 +530,7 @@ pub fn eq_foreign_item_kind(l: &ForeignItemKind, r: &ForeignItemKind) -> bool {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
                 && over(lb, rb, eq_generic_bound)
-                && both(lt, rt, |l, r| eq_ty(l, r))
+                && both(lt.as_ref(), rt.as_ref(), |l, r| eq_ty(l, r))
         },
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
         _ => false,
@@ -533,7 +553,7 @@ pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
                 ty: rt,
                 expr: re,
             }),
-        ) => eq_defaultness(*ld, *rd) && eq_generics(lg, rg) && eq_ty(lt, rt) && eq_expr_opt(le, re),
+        ) => eq_defaultness(*ld, *rd) && eq_generics(lg, rg) && eq_ty(lt, rt) && eq_expr_opt(le.as_ref(), re.as_ref()),
         (
             Fn(box ast::Fn {
                 defaultness: ld,
@@ -548,7 +568,10 @@ pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
                 body: rb,
             }),
         ) => {
-            eq_defaultness(*ld, *rd) && eq_fn_sig(lf, rf) && eq_generics(lg, rg) && both(lb, rb, |l, r| eq_block(l, r))
+            eq_defaultness(*ld, *rd)
+                && eq_fn_sig(lf, rf)
+                && eq_generics(lg, rg)
+                && both(lb.as_ref(), rb.as_ref(), |l, r| eq_block(l, r))
         },
         (
             Type(box TyAlias {
@@ -569,7 +592,7 @@ pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
                 && over(lb, rb, eq_generic_bound)
-                && both(lt, rt, |l, r| eq_ty(l, r))
+                && both(lt.as_ref(), rt.as_ref(), |l, r| eq_ty(l, r))
         },
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
         _ => false,
@@ -582,7 +605,9 @@ pub fn eq_variant(l: &Variant, r: &Variant) -> bool {
         && eq_vis(&l.vis, &r.vis)
         && eq_id(l.ident, r.ident)
         && eq_variant_data(&l.data, &r.data)
-        && both(&l.disr_expr, &r.disr_expr, |l, r| eq_expr(&l.value, &r.value))
+        && both(l.disr_expr.as_ref(), r.disr_expr.as_ref(), |l, r| {
+            eq_expr(&l.value, &r.value)
+        })
 }
 
 pub fn eq_variant_data(l: &VariantData, r: &VariantData) -> bool {
@@ -600,7 +625,7 @@ pub fn eq_struct_field(l: &FieldDef, r: &FieldDef) -> bool {
     l.is_placeholder == r.is_placeholder
         && over(&l.attrs, &r.attrs, eq_attr)
         && eq_vis(&l.vis, &r.vis)
-        && both(&l.ident, &r.ident, |l, r| eq_id(*l, *r))
+        && both(l.ident.as_ref(), r.ident.as_ref(), |l, r| eq_id(*l, *r))
         && eq_ty(&l.ty, &r.ty)
 }
 
@@ -664,7 +689,7 @@ pub fn eq_use_tree_kind(l: &UseTreeKind, r: &UseTreeKind) -> bool {
     use UseTreeKind::*;
     match (l, r) {
         (Glob, Glob) => true,
-        (Simple(l), Simple(r)) => both(l, r, |l, r| eq_id(*l, *r)),
+        (Simple(l), Simple(r)) => both(l.as_ref(), r.as_ref(), |l, r| eq_id(*l, *r)),
         (Nested { items: l, .. }, Nested { items: r, .. }) => over(l, r, |(l, _), (r, _)| eq_use_tree(l, r)),
         _ => false,
     }
@@ -726,7 +751,7 @@ pub fn eq_ty(l: &Ty, r: &Ty) -> bool {
         (Array(le, ls), Array(re, rs)) => eq_ty(le, re) && eq_expr(&ls.value, &rs.value),
         (Ptr(l), Ptr(r)) => l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty),
         (Ref(ll, l), Ref(rl, r)) => {
-            both(ll, rl, |l, r| eq_id(l.ident, r.ident)) && l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty)
+            both(ll.as_ref(), rl.as_ref(), |l, r| eq_id(l.ident, r.ident)) && l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty)
         },
         (BareFn(l), BareFn(r)) => {
             l.safety == r.safety
@@ -735,7 +760,7 @@ pub fn eq_ty(l: &Ty, r: &Ty) -> bool {
                 && eq_fn_decl(&l.decl, &r.decl)
         },
         (Tup(l), Tup(r)) => over(l, r, |l, r| eq_ty(l, r)),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
+        (Path(lq, lp), Path(rq, rp)) => both(lq.as_ref(), rq.as_ref(), eq_qself) && eq_path(lp, rp),
         (TraitObject(lg, ls), TraitObject(rg, rs)) => ls == rs && over(lg, rg, eq_generic_bound),
         (ImplTrait(_, lg), ImplTrait(_, rg)) => over(lg, rg, eq_generic_bound),
         (Typeof(l), Typeof(r)) => eq_expr(&l.value, &r.value),
@@ -771,7 +796,7 @@ pub fn eq_generic_param(l: &GenericParam, r: &GenericParam) -> bool {
         && over(&l.bounds, &r.bounds, eq_generic_bound)
         && match (&l.kind, &r.kind) {
             (Lifetime, Lifetime) => true,
-            (Type { default: l }, Type { default: r }) => both(l, r, |l, r| eq_ty(l, r)),
+            (Type { default: l }, Type { default: r }) => both(l.as_ref(), r.as_ref(), |l, r| eq_ty(l, r)),
             (
                 Const {
                     ty: lt,
@@ -783,7 +808,7 @@ pub fn eq_generic_param(l: &GenericParam, r: &GenericParam) -> bool {
                     kw_span: _,
                     default: rd,
                 },
-            ) => eq_ty(lt, rt) && both(ld, rd, eq_anon_const),
+            ) => eq_ty(lt, rt) && both(ld.as_ref(), rd.as_ref(), eq_anon_const),
             _ => false,
         }
         && over(&l.attrs, &r.attrs, eq_attr)
diff --git a/clippy_utils/src/hir_utils.rs b/clippy_utils/src/hir_utils.rs
index 76900379ac7..06a5cb1a84f 100644
--- a/clippy_utils/src/hir_utils.rs
+++ b/clippy_utils/src/hir_utils.rs
@@ -121,9 +121,9 @@ impl HirEqInterExpr<'_, '_, '_> {
 
                 // eq_pat adds the HirIds to the locals map. We therefore call it last to make sure that
                 // these only get added if the init and type is equal.
-                both(&l.init, &r.init, |l, r| self.eq_expr(l, r))
-                    && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r))
-                    && both(&l.els, &r.els, |l, r| self.eq_block(l, r))
+                both(l.init.as_ref(), r.init.as_ref(), |l, r| self.eq_expr(l, r))
+                    && both(l.ty.as_ref(), r.ty.as_ref(), |l, r| self.eq_ty(l, r))
+                    && both(l.els.as_ref(), r.els.as_ref(), |l, r| self.eq_block(l, r))
                     && self.eq_pat(l.pat, r.pat)
             },
             (&StmtKind::Expr(l), &StmtKind::Expr(r)) | (&StmtKind::Semi(l), &StmtKind::Semi(r)) => self.eq_expr(l, r),
@@ -142,7 +142,9 @@ impl HirEqInterExpr<'_, '_, '_> {
         if lspan.ctxt != SyntaxContext::root() && rspan.ctxt != SyntaxContext::root() {
             // Don't try to check in between statements inside macros.
             return over(left.stmts, right.stmts, |left, right| self.eq_stmt(left, right))
-                && both(&left.expr, &right.expr, |left, right| self.eq_expr(left, right));
+                && both(left.expr.as_ref(), right.expr.as_ref(), |left, right| {
+                    self.eq_expr(left, right)
+                });
         }
         if lspan.ctxt != rspan.ctxt {
             return false;
@@ -285,8 +287,8 @@ impl HirEqInterExpr<'_, '_, '_> {
                     })
             },
             (&ExprKind::Break(li, ref le), &ExprKind::Break(ri, ref re)) => {
-                both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
-                    && both(le, re, |l, r| self.eq_expr(l, r))
+                both(li.label.as_ref(), ri.label.as_ref(), |l, r| l.ident.name == r.ident.name)
+                    && both(le.as_ref(), re.as_ref(), |l, r| self.eq_expr(l, r))
             },
             (&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
                 self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
@@ -297,7 +299,7 @@ impl HirEqInterExpr<'_, '_, '_> {
             (&ExprKind::Closure(_l), &ExprKind::Closure(_r)) => false,
             (&ExprKind::ConstBlock(lb), &ExprKind::ConstBlock(rb)) => self.eq_body(lb.body, rb.body),
             (&ExprKind::Continue(li), &ExprKind::Continue(ri)) => {
-                both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
+                both(li.label.as_ref(), ri.label.as_ref(), |l, r| l.ident.name == r.ident.name)
             },
             (&ExprKind::DropTemps(le), &ExprKind::DropTemps(re)) => self.eq_expr(le, re),
             (&ExprKind::Field(l_f_exp, ref l_f_ident), &ExprKind::Field(r_f_exp, ref r_f_ident)) => {
@@ -305,21 +307,25 @@ impl HirEqInterExpr<'_, '_, '_> {
             },
             (&ExprKind::Index(la, li, _), &ExprKind::Index(ra, ri, _)) => self.eq_expr(la, ra) && self.eq_expr(li, ri),
             (&ExprKind::If(lc, lt, ref le), &ExprKind::If(rc, rt, ref re)) => {
-                self.eq_expr(lc, rc) && self.eq_expr(lt, rt) && both(le, re, |l, r| self.eq_expr(l, r))
+                self.eq_expr(lc, rc) && self.eq_expr(lt, rt)
+                    && both(le.as_ref(), re.as_ref(), |l, r| self.eq_expr(l, r))
             },
             (&ExprKind::Let(l), &ExprKind::Let(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)
+                self.eq_pat(l.pat, r.pat)
+                    && both(l.ty.as_ref(), r.ty.as_ref(), |l, r| self.eq_ty(l, r))
+                    && self.eq_expr(l.init, r.init)
             },
             (ExprKind::Lit(l), ExprKind::Lit(r)) => l.node == r.node,
             (&ExprKind::Loop(lb, ref ll, ref lls, _), &ExprKind::Loop(rb, ref rl, ref rls, _)) => {
-                lls == rls && self.eq_block(lb, rb) && both(ll, rl, |l, r| l.ident.name == r.ident.name)
+                lls == rls && self.eq_block(lb, rb)
+                    && both(ll.as_ref(), rl.as_ref(), |l, r| l.ident.name == r.ident.name)
             },
             (&ExprKind::Match(le, la, ref ls), &ExprKind::Match(re, ra, ref rs)) => {
                 (ls == rs || (matches!((ls, rs), (TryDesugar(_), TryDesugar(_)))))
                     && self.eq_expr(le, re)
                     && over(la, ra, |l, r| {
                         self.eq_pat(l.pat, r.pat)
-                            && both(&l.guard, &r.guard, |l, r| self.eq_expr(l, r))
+                            && both(l.guard.as_ref(), r.guard.as_ref(), |l, r| self.eq_expr(l, r))
                             && self.eq_expr(l.body, r.body)
                     })
             },
@@ -339,10 +345,10 @@ impl HirEqInterExpr<'_, '_, '_> {
             (&ExprKind::Repeat(le, ll), &ExprKind::Repeat(re, rl)) => {
                 self.eq_expr(le, re) && self.eq_array_length(ll, rl)
             },
-            (ExprKind::Ret(l), ExprKind::Ret(r)) => both(l, r, |l, r| self.eq_expr(l, r)),
+            (ExprKind::Ret(l), ExprKind::Ret(r)) => both(l.as_ref(), r.as_ref(), |l, r| self.eq_expr(l, r)),
             (&ExprKind::Struct(l_path, lf, ref lo), &ExprKind::Struct(r_path, rf, ref ro)) => {
                 self.eq_qpath(l_path, r_path)
-                    && both(lo, ro, |l, r| self.eq_expr(l, r))
+                    && both(lo.as_ref(), ro.as_ref(), |l, r| self.eq_expr(l, r))
                     && over(lf, rf, |l, r| self.eq_expr_field(l, r))
             },
             (&ExprKind::Tup(l_tup), &ExprKind::Tup(r_tup)) => self.eq_exprs(l_tup, r_tup),
@@ -450,7 +456,7 @@ impl HirEqInterExpr<'_, '_, '_> {
                 self.eq_qpath(lp, rp) && over(la, ra, |l, r| self.eq_pat(l, r)) && ls == rs
             },
             (&PatKind::Binding(lb, li, _, ref lp), &PatKind::Binding(rb, ri, _, ref rp)) => {
-                let eq = lb == rb && both(lp, rp, |l, r| self.eq_pat(l, r));
+                let eq = lb == rb && both(lp.as_ref(), rp.as_ref(), |l, r| self.eq_pat(l, r));
                 if eq {
                     self.locals.insert(li, ri);
                 }
@@ -460,13 +466,15 @@ impl HirEqInterExpr<'_, '_, '_> {
             (&PatKind::Lit(l), &PatKind::Lit(r)) => self.eq_expr(l, r),
             (&PatKind::Tuple(l, ls), &PatKind::Tuple(r, rs)) => ls == rs && over(l, r, |l, r| self.eq_pat(l, r)),
             (&PatKind::Range(ref ls, ref le, li), &PatKind::Range(ref rs, ref re, ri)) => {
-                both(ls, rs, |a, b| self.eq_expr(a, b)) && both(le, re, |a, b| self.eq_expr(a, b)) && (li == ri)
+                both(ls.as_ref(), rs.as_ref(), |a, b| self.eq_expr(a, b))
+                    && both(le.as_ref(), re.as_ref(), |a, b| self.eq_expr(a, b))
+                    && (li == ri)
             },
             (&PatKind::Ref(le, ref lm), &PatKind::Ref(re, ref rm)) => lm == rm && self.eq_pat(le, re),
             (&PatKind::Slice(ls, ref li, le), &PatKind::Slice(rs, ref ri, re)) => {
                 over(ls, rs, |l, r| self.eq_pat(l, r))
                     && over(le, re, |l, r| self.eq_pat(l, r))
-                    && both(li, ri, |l, r| self.eq_pat(l, r))
+                    && both(li.as_ref(), ri.as_ref(), |l, r| self.eq_pat(l, r))
             },
             (&PatKind::Wild, &PatKind::Wild) => true,
             _ => false,
@@ -476,7 +484,7 @@ impl HirEqInterExpr<'_, '_, '_> {
     fn eq_qpath(&mut self, left: &QPath<'_>, right: &QPath<'_>) -> bool {
         match (left, right) {
             (&QPath::Resolved(ref lty, lpath), &QPath::Resolved(ref rty, rpath)) => {
-                both(lty, rty, |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
+                both(lty.as_ref(), rty.as_ref(), |l, r| self.eq_ty(l, r)) && self.eq_path(lpath, rpath)
             },
             (&QPath::TypeRelative(lty, lseg), &QPath::TypeRelative(rty, rseg)) => {
                 self.eq_ty(lty, rty) && self.eq_path_segment(lseg, rseg)
@@ -510,7 +518,10 @@ impl HirEqInterExpr<'_, '_, '_> {
     pub fn eq_path_segment(&mut self, left: &PathSegment<'_>, right: &PathSegment<'_>) -> bool {
         // The == of idents doesn't work with different contexts,
         // we have to be explicit about hygiene
-        left.ident.name == right.ident.name && both(&left.args, &right.args, |l, r| self.eq_path_parameters(l, r))
+        left.ident.name == right.ident.name
+            && both(left.args.as_ref(), right.args.as_ref(), |l, r| {
+                self.eq_path_parameters(l, r)
+            })
     }
 
     pub fn eq_ty(&mut self, left: &Ty<'_>, right: &Ty<'_>) -> bool {
@@ -649,7 +660,7 @@ fn swap_binop<'a>(
 
 /// Checks if the two `Option`s are both `None` or some equal values as per
 /// `eq_fn`.
-pub fn both<X>(l: &Option<X>, r: &Option<X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
+pub fn both<X>(l: Option<&X>, r: Option<&X>, mut eq_fn: impl FnMut(&X, &X) -> bool) -> bool {
     l.as_ref()
         .map_or_else(|| r.is_none(), |x| r.as_ref().map_or(false, |y| eq_fn(x, y)))
 }
diff --git a/lintcheck/src/main.rs b/lintcheck/src/main.rs
index acb6eaa5278..8c62dd3ed38 100644
--- a/lintcheck/src/main.rs
+++ b/lintcheck/src/main.rs
@@ -68,7 +68,7 @@ impl Crate {
         total_crates_to_lint: usize,
         config: &LintcheckConfig,
         lint_levels_args: &[String],
-        server: &Option<LintcheckServer>,
+        server: Option<&LintcheckServer>,
     ) -> Vec<ClippyCheckOutput> {
         // advance the atomic index by one
         let index = target_dir_index.fetch_add(1, Ordering::SeqCst);
@@ -359,7 +359,7 @@ fn lintcheck(config: LintcheckConfig) {
                 crates.len(),
                 &config,
                 &lint_level_args,
-                &server,
+                server.as_ref(),
             )
         })
         .collect();
diff --git a/src/driver.rs b/src/driver.rs
index afd9df6c0fc..c66837dc998 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -74,11 +74,11 @@ fn test_has_arg() {
     assert!(!has_arg(args, "--bar"));
 }
 
-fn track_clippy_args(psess: &mut ParseSess, args_env_var: &Option<String>) {
-    psess.env_depinfo.get_mut().insert((
-        Symbol::intern("CLIPPY_ARGS"),
-        args_env_var.as_deref().map(Symbol::intern),
-    ));
+fn track_clippy_args(psess: &mut ParseSess, args_env_var: Option<&str>) {
+    psess
+        .env_depinfo
+        .get_mut()
+        .insert((Symbol::intern("CLIPPY_ARGS"), args_env_var.map(Symbol::intern)));
 }
 
 /// Track files that may be accessed at runtime in `file_depinfo` so that cargo will re-run clippy
@@ -122,7 +122,7 @@ impl rustc_driver::Callbacks for RustcCallbacks {
     fn config(&mut self, config: &mut interface::Config) {
         let clippy_args_var = self.clippy_args_var.take();
         config.psess_created = Some(Box::new(move |psess| {
-            track_clippy_args(psess, &clippy_args_var);
+            track_clippy_args(psess, clippy_args_var.as_deref());
         }));
     }
 }
@@ -139,7 +139,7 @@ impl rustc_driver::Callbacks for ClippyCallbacks {
         let previous = config.register_lints.take();
         let clippy_args_var = self.clippy_args_var.take();
         config.psess_created = Some(Box::new(move |psess| {
-            track_clippy_args(psess, &clippy_args_var);
+            track_clippy_args(psess, clippy_args_var.as_deref());
             track_files(psess);
 
             // Trigger a rebuild if CLIPPY_CONF_DIR changes. The value must be a valid string so