Merge commit 'a98e7ab8b94485be6bd03e0c6b8682ecab5b52e6' into clippyup

102 files changed, 1841 insertions, 997 deletions

diff --git a/src/tools/clippy/CHANGELOG.md b/src/tools/clippy/CHANGELOG.md
index 258a8256f53..d66e6cf7fb6 100644
--- a/src/tools/clippy/CHANGELOG.md
+++ b/src/tools/clippy/CHANGELOG.md
@@ -981,7 +981,7 @@ Released 2021-03-25
   [#6532](https://github.com/rust-lang/rust-clippy/pull/6532)
 * [`single_match`] Suggest `if` over `if let` when possible
   [#6574](https://github.com/rust-lang/rust-clippy/pull/6574)
-* [`ref_in_deref`] Use parentheses correctly in suggestion
+* `ref_in_deref` Use parentheses correctly in suggestion
   [#6609](https://github.com/rust-lang/rust-clippy/pull/6609)
 * [`stable_sort_primitive`] Clarify error message
   [#6611](https://github.com/rust-lang/rust-clippy/pull/6611)
@@ -3227,7 +3227,6 @@ Released 2018-09-13
 [`redundant_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_slicing
 [`redundant_static_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
 [`ref_binding_to_reference`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_binding_to_reference
-[`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
 [`ref_option_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_option_ref
 [`regex_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_macro
 [`repeat_once`]: https://rust-lang.github.io/rust-clippy/master/index.html#repeat_once
diff --git a/src/tools/clippy/clippy_dev/src/bless.rs b/src/tools/clippy/clippy_dev/src/bless.rs
index daf0fcc993b..dcc2502e4c5 100644
--- a/src/tools/clippy/clippy_dev/src/bless.rs
+++ b/src/tools/clippy/clippy_dev/src/bless.rs
@@ -9,9 +9,14 @@ use walkdir::WalkDir;
 
 use crate::clippy_project_root;
 
+#[cfg(not(windows))]
+static CARGO_CLIPPY_EXE: &str = "cargo-clippy";
+#[cfg(windows)]
+static CARGO_CLIPPY_EXE: &str = "cargo-clippy.exe";
+
 static CLIPPY_BUILD_TIME: SyncLazy<Option<std::time::SystemTime>> = SyncLazy::new(|| {
     let mut path = std::env::current_exe().unwrap();
-    path.set_file_name("cargo-clippy");
+    path.set_file_name(CARGO_CLIPPY_EXE);
     fs::metadata(path).ok()?.modified().ok()
 });
 
diff --git a/src/tools/clippy/clippy_dev/src/lint.rs b/src/tools/clippy/clippy_dev/src/lint.rs
index dfd16f71054..b8287980a4b 100644
--- a/src/tools/clippy/clippy_dev/src/lint.rs
+++ b/src/tools/clippy/clippy_dev/src/lint.rs
@@ -7,7 +7,6 @@ pub fn run(filename: &str) {
         .args(["-Z", "no-codegen"])
         .args(["--edition", "2021"])
         .arg(filename)
-        .env("__CLIPPY_INTERNAL_TESTS", "true")
         .status()
         .expect("failed to run cargo")
         .code();
diff --git a/src/tools/clippy/clippy_lints/src/borrow_as_ptr.rs b/src/tools/clippy/clippy_lints/src/borrow_as_ptr.rs
index b8f5217af2b..9f8eb488c29 100644
--- a/src/tools/clippy/clippy_lints/src/borrow_as_ptr.rs
+++ b/src/tools/clippy/clippy_lints/src/borrow_as_ptr.rs
@@ -94,4 +94,6 @@ impl<'tcx> LateLintPass<'tcx> for BorrowAsPtr {
             }
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
diff --git a/src/tools/clippy/clippy_lints/src/casts/unnecessary_cast.rs b/src/tools/clippy/clippy_lints/src/casts/unnecessary_cast.rs
index 1915d990c12..470c8c7ea26 100644
--- a/src/tools/clippy/clippy_lints/src/casts/unnecessary_cast.rs
+++ b/src/tools/clippy/clippy_lints/src/casts/unnecessary_cast.rs
@@ -23,15 +23,14 @@ pub(super) fn check(
 
         if_chain! {
             if let LitKind::Int(n, _) = lit.node;
-            if let Some(src) = snippet_opt(cx, lit.span);
+            if let Some(src) = snippet_opt(cx, cast_expr.span);
             if cast_to.is_floating_point();
             if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node);
             let from_nbits = 128 - n.leading_zeros();
             let to_nbits = fp_ty_mantissa_nbits(cast_to);
             if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal();
             then {
-                let literal_str = if is_unary_neg(cast_expr) { format!("-{}", num_lit.integer) } else { num_lit.integer.into() };
-                lint_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
+                lint_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
                 return true
             }
         }
@@ -48,7 +47,7 @@ pub(super) fn check(
             | LitKind::Float(_, LitFloatType::Suffixed(_))
                 if cast_from.kind() == cast_to.kind() =>
             {
-                if let Some(src) = snippet_opt(cx, lit.span) {
+                if let Some(src) = snippet_opt(cx, cast_expr.span) {
                     if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node) {
                         lint_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
                     }
@@ -113,7 +112,3 @@ fn fp_ty_mantissa_nbits(typ: Ty<'_>) -> u32 {
         _ => 0,
     }
 }
-
-fn is_unary_neg(expr: &Expr<'_>) -> bool {
-    matches!(expr.kind, ExprKind::Unary(UnOp::Neg, _))
-}
diff --git a/src/tools/clippy/clippy_lints/src/dereference.rs b/src/tools/clippy/clippy_lints/src/dereference.rs
index feb5f100de5..c0adab790f0 100644
--- a/src/tools/clippy/clippy_lints/src/dereference.rs
+++ b/src/tools/clippy/clippy_lints/src/dereference.rs
@@ -1,5 +1,6 @@
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
+use clippy_utils::sugg::has_enclosing_paren;
 use clippy_utils::ty::peel_mid_ty_refs;
 use clippy_utils::{get_parent_expr, get_parent_node, is_lint_allowed, path_to_local};
 use rustc_ast::util::parser::{PREC_POSTFIX, PREC_PREFIX};
@@ -10,11 +11,10 @@ use rustc_hir::{
     Pat, PatKind, UnOp,
 };
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
 use rustc_middle::ty::{self, Ty, TyCtxt, TyS, TypeckResults};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::{symbol::sym, Span};
-use std::iter;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -131,8 +131,6 @@ pub struct Dereferencing {
 struct StateData {
     /// Span of the top level expression
     span: Span,
-    /// The required mutability
-    target_mut: Mutability,
 }
 
 enum State {
@@ -141,9 +139,13 @@ enum State {
         // The number of calls in a sequence which changed the referenced type
         ty_changed_count: usize,
         is_final_ufcs: bool,
+        /// The required mutability
+        target_mut: Mutability,
     },
     DerefedBorrow {
-        count: u32,
+        count: usize,
+        required_precedence: i8,
+        msg: &'static str,
     },
 }
 
@@ -214,59 +216,98 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
                                     1
                                 },
                                 is_final_ufcs: matches!(expr.kind, ExprKind::Call(..)),
-                            },
-                            StateData {
-                                span: expr.span,
                                 target_mut,
                             },
+                            StateData { span: expr.span },
                         ));
                     },
                     RefOp::AddrOf => {
                         // Find the number of times the borrow is auto-derefed.
                         let mut iter = find_adjustments(cx.tcx, typeck, expr).iter();
-                        if let Some((i, adjust)) = iter.by_ref().enumerate().find_map(|(i, adjust)| {
-                            if !matches!(adjust.kind, Adjust::Deref(_)) {
-                                Some((i, adjust))
-                            } else if !adjust.target.is_ref() {
-                                // Add one to the number of references found.
-                                Some((i + 1, adjust))
+                        let mut deref_count = 0usize;
+                        let next_adjust = loop {
+                            match iter.next() {
+                                Some(adjust) => {
+                                    if !matches!(adjust.kind, Adjust::Deref(_)) {
+                                        break Some(adjust);
+                                    } else if !adjust.target.is_ref() {
+                                        deref_count += 1;
+                                        break iter.next();
+                                    }
+                                    deref_count += 1;
+                                },
+                                None => break None,
+                            };
+                        };
+
+                        // Determine the required number of references before any can be removed. In all cases the
+                        // reference made by the current expression will be removed. After that there are four cases to
+                        // handle.
+                        //
+                        // 1. Auto-borrow will trigger in the current position, so no further references are required.
+                        // 2. Auto-deref ends at a reference, or the underlying type, so one extra needs to be left to
+                        //    handle the automatically inserted re-borrow.
+                        // 3. Auto-deref hits a user-defined `Deref` impl, so at least one reference needs to exist to
+                        //    start auto-deref.
+                        // 4. If the chain of non-user-defined derefs ends with a mutable re-borrow, and re-borrow
+                        //    adjustments will not be inserted automatically, then leave one further reference to avoid
+                        //    moving a mutable borrow.
+                        //    e.g.
+                        //        fn foo<T>(x: &mut Option<&mut T>, y: &mut T) {
+                        //            let x = match x {
+                        //                // Removing the borrow will cause `x` to be moved
+                        //                Some(x) => &mut *x,
+                        //                None => y
+                        //            };
+                        //        }
+                        let deref_msg =
+                            "this expression creates a reference which is immediately dereferenced by the compiler";
+                        let borrow_msg = "this expression borrows a value the compiler would automatically borrow";
+
+                        let (required_refs, required_precedence, msg) = if is_auto_borrow_position(parent, expr.hir_id)
+                        {
+                            (1, PREC_POSTFIX, if deref_count == 1 { borrow_msg } else { deref_msg })
+                        } else if let Some(&Adjust::Borrow(AutoBorrow::Ref(_, mutability))) =
+                            next_adjust.map(|a| &a.kind)
+                        {
+                            if matches!(mutability, AutoBorrowMutability::Mut { .. })
+                                && !is_auto_reborrow_position(parent)
+                            {
+                                (3, 0, deref_msg)
                             } else {
-                                None
-                            }
-                        }) {
-                            // Found two consecutive derefs. At least one can be removed.
-                            if i > 1 {
-                                let target_mut = iter::once(adjust)
-                                    .chain(iter)
-                                    .find_map(|adjust| match adjust.kind {
-                                        Adjust::Borrow(AutoBorrow::Ref(_, m)) => Some(m.into()),
-                                        _ => None,
-                                    })
-                                    // This default should never happen. Auto-deref always reborrows.
-                                    .unwrap_or(Mutability::Not);
-                                self.state = Some((
-                                    // Subtract one for the current borrow expression, and one to cover the last
-                                    // reference which can't be removed (it's either reborrowed, or needed for
-                                    // auto-deref to happen).
-                                    State::DerefedBorrow {
-                                        count:
-                                            // Truncation here would require more than a `u32::MAX` level reference. The compiler
-                                            // does not support this.
-                                            #[allow(clippy::cast_possible_truncation)]
-                                            { i as u32 - 2 }
-                                    },
-                                    StateData {
-                                        span: expr.span,
-                                        target_mut,
-                                    },
-                                ));
+                                (2, 0, deref_msg)
                             }
+                        } else {
+                            (2, 0, deref_msg)
+                        };
+
+                        if deref_count >= required_refs {
+                            self.state = Some((
+                                State::DerefedBorrow {
+                                    // One of the required refs is for the current borrow expression, the remaining ones
+                                    // can't be removed without breaking the code. See earlier comment.
+                                    count: deref_count - required_refs,
+                                    required_precedence,
+                                    msg,
+                                },
+                                StateData { span: expr.span },
+                            ));
                         }
                     },
                     _ => (),
                 }
             },
-            (Some((State::DerefMethod { ty_changed_count, .. }, data)), RefOp::Method(_)) => {
+            (
+                Some((
+                    State::DerefMethod {
+                        target_mut,
+                        ty_changed_count,
+                        ..
+                    },
+                    data,
+                )),
+                RefOp::Method(_),
+            ) => {
                 self.state = Some((
                     State::DerefMethod {
                         ty_changed_count: if deref_method_same_type(typeck.expr_ty(expr), typeck.expr_ty(sub_expr)) {
@@ -275,12 +316,30 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
                             ty_changed_count + 1
                         },
                         is_final_ufcs: matches!(expr.kind, ExprKind::Call(..)),
+                        target_mut,
                     },
                     data,
                 ));
             },
-            (Some((State::DerefedBorrow { count }, data)), RefOp::AddrOf) if count != 0 => {
-                self.state = Some((State::DerefedBorrow { count: count - 1 }, data));
+            (
+                Some((
+                    State::DerefedBorrow {
+                        count,
+                        required_precedence,
+                        msg,
+                    },
+                    data,
+                )),
+                RefOp::AddrOf,
+            ) if count != 0 => {
+                self.state = Some((
+                    State::DerefedBorrow {
+                        count: count - 1,
+                        required_precedence,
+                        msg,
+                    },
+                    data,
+                ));
             },
 
             (Some((state, data)), _) => report(cx, expr, state, data),
@@ -455,6 +514,30 @@ fn is_linted_explicit_deref_position(parent: Option<Node<'_>>, child_id: HirId,
     }
 }
 
+/// Checks if the given expression is in a position which can be auto-reborrowed.
+/// Note: This is only correct assuming auto-deref is already occurring.
+fn is_auto_reborrow_position(parent: Option<Node<'_>>) -> bool {
+    match parent {
+        Some(Node::Expr(parent)) => matches!(parent.kind, ExprKind::MethodCall(..) | ExprKind::Call(..)),
+        Some(Node::Local(_)) => true,
+        _ => false,
+    }
+}
+
+/// Checks if the given expression is a position which can auto-borrow.
+fn is_auto_borrow_position(parent: Option<Node<'_>>, child_id: HirId) -> bool {
+    if let Some(Node::Expr(parent)) = parent {
+        match parent.kind {
+            ExprKind::MethodCall(_, [self_arg, ..], _) => self_arg.hir_id == child_id,
+            ExprKind::Field(..) => true,
+            ExprKind::Call(f, _) => f.hir_id == child_id,
+            _ => false,
+        }
+    } else {
+        false
+    }
+}
+
 /// Adjustments are sometimes made in the parent block rather than the expression itself.
 fn find_adjustments<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -503,6 +586,7 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
         State::DerefMethod {
             ty_changed_count,
             is_final_ufcs,
+            target_mut,
         } => {
             let mut app = Applicability::MachineApplicable;
             let (expr_str, expr_is_macro_call) = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app);
@@ -517,12 +601,12 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
             };
             let addr_of_str = if ty_changed_count < ref_count {
                 // Check if a reborrow from &mut T -> &T is required.
-                if data.target_mut == Mutability::Not && matches!(ty.kind(), ty::Ref(_, _, Mutability::Mut)) {
+                if target_mut == Mutability::Not && matches!(ty.kind(), ty::Ref(_, _, Mutability::Mut)) {
                     "&*"
                 } else {
                     ""
                 }
-            } else if data.target_mut == Mutability::Mut {
+            } else if target_mut == Mutability::Mut {
                 "&mut "
             } else {
                 "&"
@@ -538,7 +622,7 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
                 cx,
                 EXPLICIT_DEREF_METHODS,
                 data.span,
-                match data.target_mut {
+                match target_mut {
                     Mutability::Not => "explicit `deref` method call",
                     Mutability::Mut => "explicit `deref_mut` method call",
                 },
@@ -547,19 +631,24 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
                 app,
             );
         },
-        State::DerefedBorrow { .. } => {
+        State::DerefedBorrow {
+            required_precedence,
+            msg,
+            ..
+        } => {
             let mut app = Applicability::MachineApplicable;
             let snip = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app).0;
             span_lint_and_sugg(
                 cx,
                 NEEDLESS_BORROW,
                 data.span,
-                &format!(
-                    "this expression borrows a reference (`{}`) that is immediately dereferenced by the compiler",
-                    cx.typeck_results().expr_ty(expr),
-                ),
+                msg,
                 "change this to",
-                snip.into(),
+                if required_precedence > expr.precedence().order() && !has_enclosing_paren(&snip) {
+                    format!("({})", snip)
+                } else {
+                    snip.into()
+                },
                 app,
             );
         },
diff --git a/src/tools/clippy/clippy_lints/src/enum_variants.rs b/src/tools/clippy/clippy_lints/src/enum_variants.rs
index 4f89e567430..1f4353fa4f7 100644
--- a/src/tools/clippy/clippy_lints/src/enum_variants.rs
+++ b/src/tools/clippy/clippy_lints/src/enum_variants.rs
@@ -172,6 +172,9 @@ fn check_variant(cx: &LateContext<'_>, threshold: u64, def: &EnumDef<'_>, item_n
         let name = var.ident.name.as_str();
 
         let variant_split = camel_case_split(name);
+        if variant_split.len() == 1 {
+            return;
+        }
 
         pre = pre
             .iter()
diff --git a/src/tools/clippy/clippy_lints/src/eq_op.rs b/src/tools/clippy/clippy_lints/src/eq_op.rs
index df75b815436..24d7613e6f8 100644
--- a/src/tools/clippy/clippy_lints/src/eq_op.rs
+++ b/src/tools/clippy/clippy_lints/src/eq_op.rs
@@ -1,12 +1,16 @@
 use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
+use clippy_utils::get_enclosing_block;
 use clippy_utils::macros::{find_assert_eq_args, first_node_macro_backtrace};
 use clippy_utils::source::snippet;
 use clippy_utils::ty::{implements_trait, is_copy};
 use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, is_in_test_function};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind};
+use rustc_hir::{
+    def::Res, def_id::DefId, BinOpKind, BorrowKind, Expr, ExprKind, GenericArg, ItemKind, QPath, Ty, TyKind,
+};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{self, TyS};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 declare_clippy_lint! {
@@ -146,6 +150,13 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                         let rty = cx.typeck_results().expr_ty(r);
                         let lcpy = is_copy(cx, lty);
                         let rcpy = is_copy(cx, rty);
+                        if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
+                            if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
+                                || (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
+                            {
+                                return; // Don't lint
+                            }
+                        }
                         // either operator autorefs or both args are copyable
                         if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty.into()]) {
                             span_lint_and_then(
@@ -206,6 +217,14 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                     // &foo == bar
                     (&ExprKind::AddrOf(BorrowKind::Ref, _, l), _) => {
                         let lty = cx.typeck_results().expr_ty(l);
+                        if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
+                            let rty = cx.typeck_results().expr_ty(right);
+                            if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
+                                || (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
+                            {
+                                return; // Don't lint
+                            }
+                        }
                         let lcpy = is_copy(cx, lty);
                         if (requires_ref || lcpy)
                             && implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
@@ -230,6 +249,14 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                     // foo == &bar
                     (_, &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
                         let rty = cx.typeck_results().expr_ty(r);
+                        if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
+                            let lty = cx.typeck_results().expr_ty(left);
+                            if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
+                                || (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
+                            {
+                                return; // Don't lint
+                            }
+                        }
                         let rcpy = is_copy(cx, rty);
                         if (requires_ref || rcpy)
                             && implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
@@ -251,3 +278,43 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
         }
     }
 }
+
+fn in_impl<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, bin_op: DefId) -> Option<(&'tcx Ty<'tcx>, &'tcx Ty<'tcx>)> {
+    if_chain! {
+        if let Some(block) = get_enclosing_block(cx, e.hir_id);
+        if let Some(impl_def_id) = cx.tcx.impl_of_method(block.hir_id.owner.to_def_id());
+        let item = cx.tcx.hir().expect_item(impl_def_id.expect_local());
+        if let ItemKind::Impl(item) = &item.kind;
+        if let Some(of_trait) = &item.of_trait;
+        if let Some(seg) = of_trait.path.segments.last();
+        if let Some(Res::Def(_, trait_id)) = seg.res;
+        if trait_id == bin_op;
+        if let Some(generic_args) = seg.args;
+        if let Some(GenericArg::Type(other_ty)) = generic_args.args.last();
+
+        then {
+            Some((item.self_ty, other_ty))
+        }
+        else {
+            None
+        }
+    }
+}
+
+fn are_equal<'tcx>(cx: &LateContext<'tcx>, middle_ty: &TyS<'_>, hir_ty: &Ty<'_>) -> bool {
+    if_chain! {
+        if let ty::Adt(adt_def, _) = middle_ty.kind();
+        if let Some(local_did) = adt_def.did.as_local();
+        let item = cx.tcx.hir().expect_item(local_did);
+        let middle_ty_id = item.def_id.to_def_id();
+        if let TyKind::Path(QPath::Resolved(_, path)) = hir_ty.kind;
+        if let Res::Def(_, hir_ty_id) = path.res;
+
+        then {
+            hir_ty_id == middle_ty_id
+        }
+        else {
+            false
+        }
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/implicit_hasher.rs b/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
index 104de0ff62f..eed25e9bc0e 100644
--- a/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
+++ b/src/tools/clippy/clippy_lints/src/implicit_hasher.rs
@@ -179,7 +179,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
                             )
                             .and_then(|snip| {
                                 let i = snip.find("fn")?;
-                                Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
+                                Some(item.span.lo() + BytePos((i + snip[i..].find('(')?) as u32))
                             })
                             .expect("failed to create span for type parameters");
                             Span::new(pos, pos, item.span.ctxt(), item.span.parent())
diff --git a/src/tools/clippy/clippy_lints/src/lib.register_all.rs b/src/tools/clippy/clippy_lints/src/lib.register_all.rs
index 87fd7f99748..4721b7f2b47 100644
--- a/src/tools/clippy/clippy_lints/src/lib.register_all.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.register_all.rs
@@ -247,7 +247,6 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(redundant_slicing::REDUNDANT_SLICING),
     LintId::of(redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
     LintId::of(reference::DEREF_ADDROF),
-    LintId::of(reference::REF_IN_DEREF),
     LintId::of(regex::INVALID_REGEX),
     LintId::of(repeat_once::REPEAT_ONCE),
     LintId::of(returns::LET_AND_RETURN),
diff --git a/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs b/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs
index a21ddf73a11..bd5ff613447 100644
--- a/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.register_complexity.rs
@@ -71,7 +71,6 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec!
     LintId::of(redundant_closure_call::REDUNDANT_CLOSURE_CALL),
     LintId::of(redundant_slicing::REDUNDANT_SLICING),
     LintId::of(reference::DEREF_ADDROF),
-    LintId::of(reference::REF_IN_DEREF),
     LintId::of(repeat_once::REPEAT_ONCE),
     LintId::of(strings::STRING_FROM_UTF8_AS_BYTES),
     LintId::of(strlen_on_c_strings::STRLEN_ON_C_STRINGS),
diff --git a/src/tools/clippy/clippy_lints/src/lib.register_lints.rs b/src/tools/clippy/clippy_lints/src/lib.register_lints.rs
index 56146a0fd3a..2d2693832e9 100644
--- a/src/tools/clippy/clippy_lints/src/lib.register_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.register_lints.rs
@@ -423,7 +423,6 @@ store.register_lints(&[
     redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES,
     ref_option_ref::REF_OPTION_REF,
     reference::DEREF_ADDROF,
-    reference::REF_IN_DEREF,
     regex::INVALID_REGEX,
     regex::TRIVIAL_REGEX,
     repeat_once::REPEAT_ONCE,
diff --git a/src/tools/clippy/clippy_lints/src/lib.rs b/src/tools/clippy/clippy_lints/src/lib.rs
index 79e9882fef4..f2a7e925dd3 100644
--- a/src/tools/clippy/clippy_lints/src/lib.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.rs
@@ -581,6 +581,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(move || Box::new(needless_question_mark::NeedlessQuestionMark));
     store.register_late_pass(move || Box::new(casts::Casts::new(msrv)));
     store.register_early_pass(move || Box::new(unnested_or_patterns::UnnestedOrPatterns::new(msrv)));
+    store.register_late_pass(move || Box::new(map_clone::MapClone::new(msrv)));
 
     store.register_late_pass(|| Box::new(size_of_in_element_count::SizeOfInElementCount));
     store.register_late_pass(|| Box::new(same_name_method::SameNameMethod));
@@ -591,7 +592,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
             msrv,
         ))
     });
-    store.register_late_pass(|| Box::new(map_clone::MapClone));
     store.register_late_pass(|| Box::new(map_err_ignore::MapErrIgnore));
     store.register_late_pass(|| Box::new(shadow::Shadow::default()));
     store.register_late_pass(|| Box::new(unit_types::UnitTypes));
@@ -703,7 +703,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(mut_key::MutableKeyType));
     store.register_late_pass(|| Box::new(modulo_arithmetic::ModuloArithmetic));
     store.register_early_pass(|| Box::new(reference::DerefAddrOf));
-    store.register_early_pass(|| Box::new(reference::RefInDeref));
     store.register_early_pass(|| Box::new(double_parens::DoubleParens));
     store.register_late_pass(|| Box::new(to_string_in_display::ToStringInDisplay::new()));
     store.register_early_pass(|| Box::new(unsafe_removed_from_name::UnsafeNameRemoval));
@@ -935,6 +934,7 @@ pub fn register_renamed(ls: &mut rustc_lint::LintStore) {
     ls.register_renamed("clippy::if_let_some_result", "clippy::match_result_ok");
     ls.register_renamed("clippy::disallowed_type", "clippy::disallowed_types");
     ls.register_renamed("clippy::disallowed_method", "clippy::disallowed_methods");
+    ls.register_renamed("clippy::ref_in_deref", "clippy::needless_borrow");
 
     // uplifted lints
     ls.register_renamed("clippy::invalid_ref", "invalid_value");
diff --git a/src/tools/clippy/clippy_lints/src/lifetimes.rs b/src/tools/clippy/clippy_lints/src/lifetimes.rs
index 56505714045..b09c23f31e9 100644
--- a/src/tools/clippy/clippy_lints/src/lifetimes.rs
+++ b/src/tools/clippy/clippy_lints/src/lifetimes.rs
@@ -13,7 +13,7 @@ use rustc_hir::{
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::{kw, Symbol};
+use rustc_span::symbol::{kw, Ident, Symbol};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -83,7 +83,7 @@ declare_lint_pass!(Lifetimes => [NEEDLESS_LIFETIMES, EXTRA_UNUSED_LIFETIMES]);
 impl<'tcx> LateLintPass<'tcx> for Lifetimes {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
         if let ItemKind::Fn(ref sig, ref generics, id) = item.kind {
-            check_fn_inner(cx, sig.decl, Some(id), generics, item.span, true);
+            check_fn_inner(cx, sig.decl, Some(id), None, generics, item.span, true);
         }
     }
 
@@ -94,6 +94,7 @@ impl<'tcx> LateLintPass<'tcx> for Lifetimes {
                 cx,
                 sig.decl,
                 Some(id),
+                None,
                 &item.generics,
                 item.span,
                 report_extra_lifetimes,
@@ -103,11 +104,11 @@ impl<'tcx> LateLintPass<'tcx> for Lifetimes {
 
     fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
         if let TraitItemKind::Fn(ref sig, ref body) = item.kind {
-            let body = match *body {
-                TraitFn::Required(_) => None,
-                TraitFn::Provided(id) => Some(id),
+            let (body, trait_sig) = match *body {
+                TraitFn::Required(sig) => (None, Some(sig)),
+                TraitFn::Provided(id) => (Some(id), None),
             };
-            check_fn_inner(cx, sig.decl, body, &item.generics, item.span, true);
+            check_fn_inner(cx, sig.decl, body, trait_sig, &item.generics, item.span, true);
         }
     }
 }
@@ -124,6 +125,7 @@ fn check_fn_inner<'tcx>(
     cx: &LateContext<'tcx>,
     decl: &'tcx FnDecl<'_>,
     body: Option<BodyId>,
+    trait_sig: Option<&[Ident]>,
     generics: &'tcx Generics<'_>,
     span: Span,
     report_extra_lifetimes: bool,
@@ -165,7 +167,7 @@ fn check_fn_inner<'tcx>(
             }
         }
     }
-    if could_use_elision(cx, decl, body, generics.params) {
+    if could_use_elision(cx, decl, body, trait_sig, generics.params) {
         span_lint(
             cx,
             NEEDLESS_LIFETIMES,
@@ -179,10 +181,31 @@ fn check_fn_inner<'tcx>(
     }
 }
 
+// elision doesn't work for explicit self types, see rust-lang/rust#69064
+fn explicit_self_type<'tcx>(cx: &LateContext<'tcx>, func: &FnDecl<'tcx>, ident: Option<Ident>) -> bool {
+    if_chain! {
+        if let Some(ident) = ident;
+        if ident.name == kw::SelfLower;
+        if !func.implicit_self.has_implicit_self();
+
+        if let Some(self_ty) = func.inputs.first();
+        then {
+            let mut visitor = RefVisitor::new(cx);
+            visitor.visit_ty(self_ty);
+
+            !visitor.all_lts().is_empty()
+        }
+        else {
+            false
+        }
+    }
+}
+
 fn could_use_elision<'tcx>(
     cx: &LateContext<'tcx>,
     func: &'tcx FnDecl<'_>,
     body: Option<BodyId>,
+    trait_sig: Option<&[Ident]>,
     named_generics: &'tcx [GenericParam<'_>],
 ) -> bool {
     // There are two scenarios where elision works:
@@ -233,11 +256,24 @@ fn could_use_elision<'tcx>(
     let input_lts = input_visitor.lts;
     let output_lts = output_visitor.lts;
 
+    if let Some(trait_sig) = trait_sig {
+        if explicit_self_type(cx, func, trait_sig.first().copied()) {
+            return false;
+        }
+    }
+
     if let Some(body_id) = body {
+        let body = cx.tcx.hir().body(body_id);
+
+        let first_ident = body.params.first().and_then(|param| param.pat.simple_ident());
+        if explicit_self_type(cx, func, first_ident) {
+            return false;
+        }
+
         let mut checker = BodyLifetimeChecker {
             lifetimes_used_in_body: false,
         };
-        checker.visit_expr(&cx.tcx.hir().body(body_id).value);
+        checker.visit_expr(&body.value);
         if checker.lifetimes_used_in_body {
             return false;
         }
diff --git a/src/tools/clippy/clippy_lints/src/manual_async_fn.rs b/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
index 2af3555e370..babc6fab3c0 100644
--- a/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_async_fn.rs
@@ -6,8 +6,8 @@ use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{
-    Term, AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericArg, GenericBound, HirId,
-    IsAsync, ItemKind, LifetimeName, TraitRef, Ty, TyKind, TypeBindingKind,
+    AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericArg, GenericBound, HirId,
+    IsAsync, ItemKind, LifetimeName, Term, TraitRef, Ty, TyKind, TypeBindingKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
diff --git a/src/tools/clippy/clippy_lints/src/manual_bits.rs b/src/tools/clippy/clippy_lints/src/manual_bits.rs
index 50bf2527e39..809aa168a7a 100644
--- a/src/tools/clippy/clippy_lints/src/manual_bits.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_bits.rs
@@ -72,6 +72,8 @@ impl<'tcx> LateLintPass<'tcx> for ManualBits {
             }
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
 
 fn get_one_size_of_ty<'tcx>(
diff --git a/src/tools/clippy/clippy_lints/src/map_clone.rs b/src/tools/clippy/clippy_lints/src/map_clone.rs
index 22a2552b283..3f8eeb736fb 100644
--- a/src/tools/clippy/clippy_lints/src/map_clone.rs
+++ b/src/tools/clippy/clippy_lints/src/map_clone.rs
@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::{is_copy, is_type_diagnostic_item};
-use clippy_utils::{is_trait_method, peel_blocks};
+use clippy_utils::{is_trait_method, meets_msrv, msrvs, peel_blocks};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
@@ -9,7 +9,8 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::mir::Mutability;
 use rustc_middle::ty;
 use rustc_middle::ty::adjustment::Adjust;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::symbol::Ident;
 use rustc_span::{sym, Span};
 
@@ -42,7 +43,17 @@ declare_clippy_lint! {
     "using `iterator.map(|x| x.clone())`, or dereferencing closures for `Copy` types"
 }
 
-declare_lint_pass!(MapClone => [MAP_CLONE]);
+pub struct MapClone {
+    msrv: Option<RustcVersion>,
+}
+
+impl_lint_pass!(MapClone => [MAP_CLONE]);
+
+impl MapClone {
+    pub fn new(msrv: Option<RustcVersion>) -> Self {
+        Self { msrv }
+    }
+}
 
 impl<'tcx> LateLintPass<'tcx> for MapClone {
     fn check_expr(&mut self, cx: &LateContext<'_>, e: &hir::Expr<'_>) {
@@ -65,7 +76,7 @@ impl<'tcx> LateLintPass<'tcx> for MapClone {
                         hir::BindingAnnotation::Unannotated, .., name, None
                     ) = inner.kind {
                         if ident_eq(name, closure_expr) {
-                            lint(cx, e.span, args[0].span, true);
+                            self.lint_explicit_closure(cx, e.span, args[0].span, true);
                         }
                     },
                     hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, .., name, None) => {
@@ -73,7 +84,7 @@ impl<'tcx> LateLintPass<'tcx> for MapClone {
                             hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
                                 if ident_eq(name, inner) {
                                     if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
-                                        lint(cx, e.span, args[0].span, true);
+                                        self.lint_explicit_closure(cx, e.span, args[0].span, true);
                                     }
                                 }
                             },
@@ -90,7 +101,7 @@ impl<'tcx> LateLintPass<'tcx> for MapClone {
                                     if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
                                         if matches!(mutability, Mutability::Not) {
                                             let copy = is_copy(cx, ty);
-                                            lint(cx, e.span, args[0].span, copy);
+                                            self.lint_explicit_closure(cx, e.span, args[0].span, copy);
                                         }
                                     } else {
                                         lint_needless_cloning(cx, e.span, args[0].span);
@@ -105,6 +116,8 @@ impl<'tcx> LateLintPass<'tcx> for MapClone {
             }
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
 
 fn ident_eq(name: Ident, path: &hir::Expr<'_>) -> bool {
@@ -127,31 +140,30 @@ fn lint_needless_cloning(cx: &LateContext<'_>, root: Span, receiver: Span) {
     );
 }
 
-fn lint(cx: &LateContext<'_>, replace: Span, root: Span, copied: bool) {
-    let mut applicability = Applicability::MachineApplicable;
-    if copied {
-        span_lint_and_sugg(
-            cx,
-            MAP_CLONE,
-            replace,
-            "you are using an explicit closure for copying elements",
-            "consider calling the dedicated `copied` method",
-            format!(
-                "{}.copied()",
-                snippet_with_applicability(cx, root, "..", &mut applicability)
-            ),
-            applicability,
-        );
-    } else {
+impl MapClone {
+    fn lint_explicit_closure(&self, cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool) {
+        let mut applicability = Applicability::MachineApplicable;
+        let message = if is_copy {
+            "you are using an explicit closure for copying elements"
+        } else {
+            "you are using an explicit closure for cloning elements"
+        };
+        let sugg_method = if is_copy && meets_msrv(self.msrv.as_ref(), &msrvs::ITERATOR_COPIED) {
+            "copied"
+        } else {
+            "cloned"
+        };
+
         span_lint_and_sugg(
             cx,
             MAP_CLONE,
             replace,
-            "you are using an explicit closure for cloning elements",
-            "consider calling the dedicated `cloned` method",
+            message,
+            &format!("consider calling the dedicated `{}` method", sugg_method),
             format!(
-                "{}.cloned()",
-                snippet_with_applicability(cx, root, "..", &mut applicability)
+                "{}.{}()",
+                snippet_with_applicability(cx, root, "..", &mut applicability),
+                sugg_method,
             ),
             applicability,
         );
diff --git a/src/tools/clippy/clippy_lints/src/matches.rs b/src/tools/clippy/clippy_lints/src/matches.rs
index dfb450c8848..2579404fb18 100644
--- a/src/tools/clippy/clippy_lints/src/matches.rs
+++ b/src/tools/clippy/clippy_lints/src/matches.rs
@@ -30,7 +30,7 @@ use rustc_middle::ty::{self, Ty, TyS, VariantDef};
 use rustc_semver::RustcVersion;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::{Span, Spanned};
-use rustc_span::sym;
+use rustc_span::{sym, symbol::kw};
 use std::cmp::Ordering;
 use std::collections::hash_map::Entry;
 
@@ -961,13 +961,13 @@ fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm
                 let path_str = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false));
                 if path_str == "Err" {
                     let mut matching_wild = inner.iter().any(is_wild);
-                    let mut ident_bind_name = String::from("_");
+                    let mut ident_bind_name = kw::Underscore;
                     if !matching_wild {
                         // Looking for unused bindings (i.e.: `_e`)
                         for pat in inner.iter() {
                             if let PatKind::Binding(_, id, ident, None) = pat.kind {
                                 if ident.as_str().starts_with('_') && !is_local_used(cx, arm.body, id) {
-                                    ident_bind_name = ident.name.as_str().to_string();
+                                    ident_bind_name = ident.name;
                                     matching_wild = true;
                                 }
                             }
@@ -982,7 +982,7 @@ fn check_wild_err_arm<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm
                             span_lint_and_note(cx,
                                 MATCH_WILD_ERR_ARM,
                                 arm.pat.span,
-                                &format!("`Err({})` matches all errors", &ident_bind_name),
+                                &format!("`Err({})` matches all errors", ident_bind_name),
                                 None,
                                 "match each error separately or use the error output, or use `.except(msg)` if the error case is unreachable",
                             );
diff --git a/src/tools/clippy/clippy_lints/src/methods/expect_fun_call.rs b/src/tools/clippy/clippy_lints/src/methods/expect_fun_call.rs
index e7d2d550a30..d813edab687 100644
--- a/src/tools/clippy/clippy_lints/src/methods/expect_fun_call.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/expect_fun_call.rs
@@ -30,7 +30,7 @@ pub(super) fn check<'tcx>(
                 hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, expr) => expr,
                 hir::ExprKind::MethodCall(method_name, call_args, _) => {
                     if call_args.len() == 1
-                        && (method_name.ident.name == sym::as_str || method_name.ident.name == sym!(as_ref))
+                        && (method_name.ident.name == sym::as_str || method_name.ident.name == sym::as_ref)
                         && {
                             let arg_type = cx.typeck_results().expr_ty(&call_args[0]);
                             let base_type = arg_type.peel_refs();
diff --git a/src/tools/clippy/clippy_lints/src/methods/mod.rs b/src/tools/clippy/clippy_lints/src/methods/mod.rs
index 137c9628eb4..4b43448bf7b 100644
--- a/src/tools/clippy/clippy_lints/src/methods/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/mod.rs
@@ -2180,8 +2180,8 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) {
                     if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() {
                         let assoc_ty = match projection_predicate.term {
-                          ty::Term::Ty(ty) => ty,
-                          ty::Term::Const(_c) => continue,
+                            ty::Term::Ty(ty) => ty,
+                            ty::Term::Const(_c) => continue,
                         };
                         // walk the associated type and check for Self
                         if let Some(self_adt) = self_ty.ty_adt_def() {
diff --git a/src/tools/clippy/clippy_lints/src/needless_question_mark.rs b/src/tools/clippy/clippy_lints/src/needless_question_mark.rs
index 0e7ae43ce2d..d4c823d1c1a 100644
--- a/src/tools/clippy/clippy_lints/src/needless_question_mark.rs
+++ b/src/tools/clippy/clippy_lints/src/needless_question_mark.rs
@@ -4,7 +4,7 @@ use clippy_utils::source::snippet;
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::LangItem::{OptionSome, ResultOk};
-use rustc_hir::{Body, Expr, ExprKind, LangItem, MatchSource, QPath};
+use rustc_hir::{AsyncGeneratorKind, Block, Body, Expr, ExprKind, GeneratorKind, LangItem, MatchSource, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::TyS;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -88,7 +88,26 @@ impl LateLintPass<'_> for NeedlessQuestionMark {
     }
 
     fn check_body(&mut self, cx: &LateContext<'_>, body: &'_ Body<'_>) {
-        check(cx, body.value.peel_blocks());
+        if let Some(GeneratorKind::Async(AsyncGeneratorKind::Fn)) = body.generator_kind {
+            if let ExprKind::Block(
+                Block {
+                    expr:
+                        Some(Expr {
+                            kind: ExprKind::DropTemps(async_body),
+                            ..
+                        }),
+                    ..
+                },
+                _,
+            ) = body.value.kind
+            {
+                if let ExprKind::Block(Block { expr: Some(expr), .. }, ..) = async_body.kind {
+                    check(cx, expr);
+                }
+            }
+        } else {
+            check(cx, body.value.peel_blocks());
+        }
     }
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/octal_escapes.rs b/src/tools/clippy/clippy_lints/src/octal_escapes.rs
index d81481ade04..c19cea66104 100644
--- a/src/tools/clippy/clippy_lints/src/octal_escapes.rs
+++ b/src/tools/clippy/clippy_lints/src/octal_escapes.rs
@@ -101,7 +101,7 @@ fn check_lit(cx: &EarlyContext<'_>, lit: &Lit, span: Span, is_string: bool) {
         // construct a replacement escape
         // the maximum value is \077, or \x3f, so u8 is sufficient here
         if let Ok(n) = u8::from_str_radix(&contents[from + 1..to], 8) {
-            write!(&mut suggest_1, "\\x{:02x}", n).unwrap();
+            write!(suggest_1, "\\x{:02x}", n).unwrap();
         }
 
         // append the null byte as \x00 and the following digits literally
diff --git a/src/tools/clippy/clippy_lints/src/ptr.rs b/src/tools/clippy/clippy_lints/src/ptr.rs
index 63de117a6f1..b5d65542de0 100644
--- a/src/tools/clippy/clippy_lints/src/ptr.rs
+++ b/src/tools/clippy/clippy_lints/src/ptr.rs
@@ -1,30 +1,36 @@
 //! Checks for usage of  `&Vec[_]` and `&String`.
 
 use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then};
-use clippy_utils::ptr::get_spans;
 use clippy_utils::source::snippet_opt;
-use clippy_utils::ty::walk_ptrs_hir_ty;
-use clippy_utils::{expr_path_res, is_lint_allowed, match_any_diagnostic_items, paths};
+use clippy_utils::ty::expr_sig;
+use clippy_utils::{
+    expr_path_res, get_expr_use_or_unification_node, is_lint_allowed, match_any_diagnostic_items, path_to_local, paths,
+};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::def::Res;
+use rustc_hir::def_id::DefId;
+use rustc_hir::hir_id::HirIdMap;
+use rustc_hir::intravisit::{walk_expr, Visitor};
 use rustc_hir::{
-    BinOpKind, BodyId, Expr, ExprKind, FnDecl, FnRetTy, GenericArg, Impl, ImplItem, ImplItemKind, Item, ItemKind,
-    Lifetime, MutTy, Mutability, Node, PathSegment, QPath, TraitFn, TraitItem, TraitItemKind, Ty, TyKind,
+    self as hir, AnonConst, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, FnRetTy, GenericArg,
+    ImplItemKind, ItemKind, Lifetime, LifetimeName, Mutability, Node, Param, ParamName, PatKind, QPath, TraitFn,
+    TraitItem, TraitItemKind, TyKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::hir::nested_filter;
+use rustc_middle::ty::{self, AssocItems, AssocKind, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
 use rustc_span::{sym, MultiSpan};
-use std::borrow::Cow;
+use std::fmt;
+use std::iter;
 
 declare_clippy_lint! {
     /// ### What it does
-    /// This lint checks for function arguments of type `&String`
-    /// or `&Vec` unless the references are mutable. It will also suggest you
-    /// replace `.clone()` calls with the appropriate `.to_owned()`/`to_string()`
-    /// calls.
+    /// This lint checks for function arguments of type `&String`, `&Vec`,
+    /// `&PathBuf`, and `Cow<_>`. It will also suggest you replace `.clone()` calls
+    /// with the appropriate `.to_owned()`/`to_string()` calls.
     ///
     /// ### Why is this bad?
     /// Requiring the argument to be of the specific size
@@ -32,28 +38,7 @@ declare_clippy_lint! {
     /// or `&str` usually suffice and can be obtained from other types, too.
     ///
     /// ### Known problems
-    /// The lint does not follow data. So if you have an
-    /// argument `x` and write `let y = x; y.clone()` the lint will not suggest
-    /// changing that `.clone()` to `.to_owned()`.
-    ///
-    /// Other functions called from this function taking a `&String` or `&Vec`
-    /// argument may also fail to compile if you change the argument. Applying
-    /// this lint on them will fix the problem, but they may be in other crates.
-    ///
-    /// One notable example of a function that may cause issues, and which cannot
-    /// easily be changed due to being in the standard library is `Vec::contains`.
-    /// when called on a `Vec<Vec<T>>`. If a `&Vec` is passed to that method then
-    /// it will compile, but if a `&[T]` is passed then it will not compile.
-    ///
-    /// ```ignore
-    /// fn cannot_take_a_slice(v: &Vec<u8>) -> bool {
-    ///     let vec_of_vecs: Vec<Vec<u8>> = some_other_fn();
-    ///
-    ///     vec_of_vecs.contains(v)
-    /// }
-    /// ```
-    ///
-    /// Also there may be `fn(&Vec)`-typed references pointing to your function.
+    /// There may be `fn(&Vec)`-typed references pointing to your function.
     /// If you have them, you will get a compiler error after applying this lint's
     /// suggestions. You then have the choice to undo your changes or change the
     /// type of the reference.
@@ -155,32 +140,86 @@ declare_clippy_lint! {
 declare_lint_pass!(Ptr => [PTR_ARG, CMP_NULL, MUT_FROM_REF, INVALID_NULL_PTR_USAGE]);
 
 impl<'tcx> LateLintPass<'tcx> for Ptr {
-    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
-        if let ItemKind::Fn(ref sig, _, body_id) = item.kind {
-            check_fn(cx, sig.decl, Some(body_id));
-        }
-    }
+    fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
+        if let TraitItemKind::Fn(sig, trait_method) = &item.kind {
+            if matches!(trait_method, TraitFn::Provided(_)) {
+                // Handled by check body.
+                return;
+            }
 
-    fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
-        if let ImplItemKind::Fn(ref sig, body_id) = item.kind {
-            let parent_item = cx.tcx.hir().get_parent_item(item.hir_id());
-            if let Some(Node::Item(it)) = cx.tcx.hir().find_by_def_id(parent_item) {
-                if let ItemKind::Impl(Impl { of_trait: Some(_), .. }) = it.kind {
-                    return; // ignore trait impls
-                }
+            check_mut_from_ref(cx, sig.decl);
+            for arg in check_fn_args(
+                cx,
+                cx.tcx.fn_sig(item.def_id).skip_binder().inputs(),
+                sig.decl.inputs,
+                &[],
+            ) {
+                span_lint_and_sugg(
+                    cx,
+                    PTR_ARG,
+                    arg.span,
+                    &arg.build_msg(),
+                    "change this to",
+                    format!("{}{}", arg.ref_prefix, arg.deref_ty.display(cx)),
+                    Applicability::Unspecified,
+                );
             }
-            check_fn(cx, sig.decl, Some(body_id));
         }
     }
 
-    fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
-        if let TraitItemKind::Fn(ref sig, ref trait_method) = item.kind {
-            let body_id = if let TraitFn::Provided(b) = *trait_method {
-                Some(b)
-            } else {
-                None
-            };
-            check_fn(cx, sig.decl, body_id);
+    fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) {
+        let hir = cx.tcx.hir();
+        let mut parents = hir.parent_iter(body.value.hir_id);
+        let (item_id, decl) = match parents.next() {
+            Some((_, Node::Item(i))) => {
+                if let ItemKind::Fn(sig, ..) = &i.kind {
+                    (i.def_id, sig.decl)
+                } else {
+                    return;
+                }
+            },
+            Some((_, Node::ImplItem(i))) => {
+                if !matches!(parents.next(),
+                    Some((_, Node::Item(i))) if matches!(&i.kind, ItemKind::Impl(i) if i.of_trait.is_none())
+                ) {
+                    return;
+                }
+                if let ImplItemKind::Fn(sig, _) = &i.kind {
+                    (i.def_id, sig.decl)
+                } else {
+                    return;
+                }
+            },
+            Some((_, Node::TraitItem(i))) => {
+                if let TraitItemKind::Fn(sig, _) = &i.kind {
+                    (i.def_id, sig.decl)
+                } else {
+                    return;
+                }
+            },
+            _ => return,
+        };
+
+        check_mut_from_ref(cx, decl);
+        let sig = cx.tcx.fn_sig(item_id).skip_binder();
+        let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, body.params).collect();
+        let results = check_ptr_arg_usage(cx, body, &lint_args);
+
+        for (result, args) in results.iter().zip(lint_args.iter()).filter(|(r, _)| !r.skip) {
+            span_lint_and_then(cx, PTR_ARG, args.span, &args.build_msg(), |diag| {
+                diag.multipart_suggestion(
+                    "change this to",
+                    iter::once((args.span, format!("{}{}", args.ref_prefix, args.deref_ty.display(cx))))
+                        .chain(result.replacements.iter().map(|r| {
+                            (
+                                r.expr_span,
+                                format!("{}{}", snippet_opt(cx, r.self_span).unwrap(), r.replacement),
+                            )
+                        }))
+                        .collect(),
+                    Applicability::Unspecified,
+                );
+            });
         }
     }
 
@@ -247,154 +286,206 @@ fn check_invalid_ptr_usage<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
     }
 }
 
-#[allow(clippy::too_many_lines)]
-fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, opt_body_id: Option<BodyId>) {
-    let body = opt_body_id.map(|id| cx.tcx.hir().body(id));
-
-    for (idx, arg) in decl.inputs.iter().enumerate() {
-        // Honor the allow attribute on parameters. See issue 5644.
-        if let Some(body) = &body {
-            if is_lint_allowed(cx, PTR_ARG, body.params[idx].hir_id) {
-                continue;
-            }
-        }
+#[derive(Default)]
+struct PtrArgResult {
+    skip: bool,
+    replacements: Vec<PtrArgReplacement>,
+}
 
-        let (item_name, path) = if_chain! {
-            if let TyKind::Rptr(_, MutTy { ty, mutbl: Mutability::Not }) = arg.kind;
-            if let TyKind::Path(QPath::Resolved(_, path)) = ty.kind;
-            if let Res::Def(_, did) = path.res;
-            if let Some(item_name) = cx.tcx.get_diagnostic_name(did);
-            then {
-                (item_name, path)
-            } else {
-                continue
-            }
-        };
+struct PtrArgReplacement {
+    expr_span: Span,
+    self_span: Span,
+    replacement: &'static str,
+}
 
-        match item_name {
-            sym::Vec => {
-                if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_owned()")]) {
-                    span_lint_and_then(
-                        cx,
-                        PTR_ARG,
-                        arg.span,
-                        "writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \
-                         with non-Vec-based slices",
-                        |diag| {
-                            if let Some(ref snippet) = get_only_generic_arg_snippet(cx, arg) {
-                                diag.span_suggestion(
-                                    arg.span,
-                                    "change this to",
-                                    format!("&[{}]", snippet),
-                                    Applicability::Unspecified,
-                                );
-                            }
-                            for (clonespan, suggestion) in spans {
-                                diag.span_suggestion(
-                                    clonespan,
-                                    &snippet_opt(cx, clonespan).map_or("change the call to".into(), |x| {
-                                        Cow::Owned(format!("change `{}` to", x))
-                                    }),
-                                    suggestion.into(),
-                                    Applicability::Unspecified,
-                                );
-                            }
-                        },
-                    );
-                }
+struct PtrArg<'tcx> {
+    idx: usize,
+    span: Span,
+    ty_did: DefId,
+    ty_name: Symbol,
+    method_renames: &'static [(&'static str, &'static str)],
+    ref_prefix: RefPrefix,
+    deref_ty: DerefTy<'tcx>,
+    deref_assoc_items: Option<(DefId, &'tcx AssocItems<'tcx>)>,
+}
+impl PtrArg<'_> {
+    fn build_msg(&self) -> String {
+        format!(
+            "writing `&{}{}` instead of `&{}{}` involves a new object where a slice will do",
+            self.ref_prefix.mutability.prefix_str(),
+            self.ty_name,
+            self.ref_prefix.mutability.prefix_str(),
+            self.deref_ty.argless_str(),
+        )
+    }
+}
+
+struct RefPrefix {
+    lt: LifetimeName,
+    mutability: Mutability,
+}
+impl fmt::Display for RefPrefix {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use fmt::Write;
+        f.write_char('&')?;
+        match self.lt {
+            LifetimeName::Param(ParamName::Plain(name)) => {
+                name.fmt(f)?;
+                f.write_char(' ')?;
             },
-            sym::String => {
-                if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_string()"), ("as_str", "")]) {
-                    span_lint_and_then(
-                        cx,
-                        PTR_ARG,
-                        arg.span,
-                        "writing `&String` instead of `&str` involves a new object where a slice will do",
-                        |diag| {
-                            diag.span_suggestion(arg.span, "change this to", "&str".into(), Applicability::Unspecified);
-                            for (clonespan, suggestion) in spans {
-                                diag.span_suggestion_short(
-                                    clonespan,
-                                    &snippet_opt(cx, clonespan).map_or("change the call to".into(), |x| {
-                                        Cow::Owned(format!("change `{}` to", x))
-                                    }),
-                                    suggestion.into(),
-                                    Applicability::Unspecified,
-                                );
-                            }
-                        },
-                    );
+            LifetimeName::Underscore => f.write_str("'_ ")?,
+            LifetimeName::Static => f.write_str("'static ")?,
+            _ => (),
+        }
+        f.write_str(self.mutability.prefix_str())
+    }
+}
+
+struct DerefTyDisplay<'a, 'tcx>(&'a LateContext<'tcx>, &'a DerefTy<'tcx>);
+impl fmt::Display for DerefTyDisplay<'_, '_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use std::fmt::Write;
+        match self.1 {
+            DerefTy::Str => f.write_str("str"),
+            DerefTy::Path => f.write_str("Path"),
+            DerefTy::Slice(hir_ty, ty) => {
+                f.write_char('[')?;
+                match hir_ty.and_then(|s| snippet_opt(self.0, s)) {
+                    Some(s) => f.write_str(&s)?,
+                    None => ty.fmt(f)?,
                 }
+                f.write_char(']')
             },
-            sym::PathBuf => {
-                if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_path_buf()"), ("as_path", "")]) {
-                    span_lint_and_then(
-                        cx,
-                        PTR_ARG,
-                        arg.span,
-                        "writing `&PathBuf` instead of `&Path` involves a new object where a slice will do",
-                        |diag| {
-                            diag.span_suggestion(
-                                arg.span,
+        }
+    }
+}
+
+enum DerefTy<'tcx> {
+    Str,
+    Path,
+    Slice(Option<Span>, Ty<'tcx>),
+}
+impl<'tcx> DerefTy<'tcx> {
+    fn argless_str(&self) -> &'static str {
+        match *self {
+            Self::Str => "str",
+            Self::Path => "Path",
+            Self::Slice(..) => "[_]",
+        }
+    }
+
+    fn display<'a>(&'a self, cx: &'a LateContext<'tcx>) -> DerefTyDisplay<'a, 'tcx> {
+        DerefTyDisplay(cx, self)
+    }
+}
+
+fn check_fn_args<'cx, 'tcx: 'cx>(
+    cx: &'cx LateContext<'tcx>,
+    tys: &'tcx [Ty<'_>],
+    hir_tys: &'tcx [hir::Ty<'_>],
+    params: &'tcx [Param<'_>],
+) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx {
+    tys.iter()
+        .zip(hir_tys.iter())
+        .enumerate()
+        .filter_map(|(i, (ty, hir_ty))| {
+            if_chain! {
+                if let ty::Ref(_, ty, mutability) = *ty.kind();
+                if let ty::Adt(adt, substs) = *ty.kind();
+
+                if let TyKind::Rptr(lt, ref ty) = hir_ty.kind;
+                if let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind;
+
+                // Check that the name as typed matches the actual name of the type.
+                // e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec`
+                if let [.., name] = path.segments;
+                if cx.tcx.item_name(adt.did) == name.ident.name;
+
+                if !is_lint_allowed(cx, PTR_ARG, hir_ty.hir_id);
+                if params.get(i).map_or(true, |p| !is_lint_allowed(cx, PTR_ARG, p.hir_id));
+
+                then {
+                    let (method_renames, deref_ty, deref_impl_id) = match cx.tcx.get_diagnostic_name(adt.did) {
+                        Some(sym::Vec) => (
+                            [("clone", ".to_owned()")].as_slice(),
+                            DerefTy::Slice(
+                                name.args
+                                    .and_then(|args| args.args.first())
+                                    .and_then(|arg| if let GenericArg::Type(ty) = arg {
+                                        Some(ty.span)
+                                    } else {
+                                        None
+                                    }),
+                                substs.type_at(0),
+                            ),
+                            cx.tcx.lang_items().slice_impl()
+                        ),
+                        Some(sym::String) => (
+                            [("clone", ".to_owned()"), ("as_str", "")].as_slice(),
+                            DerefTy::Str,
+                            cx.tcx.lang_items().str_impl()
+                        ),
+                        Some(sym::PathBuf) => (
+                            [("clone", ".to_path_buf()"), ("as_path", "")].as_slice(),
+                            DerefTy::Path,
+                            None,
+                        ),
+                        Some(sym::Cow) => {
+                            let ty_name = name.args
+                                .and_then(|args| {
+                                    args.args.iter().find_map(|a| match a {
+                                        GenericArg::Type(x) => Some(x),
+                                        _ => None,
+                                    })
+                                })
+                                .and_then(|arg| snippet_opt(cx, arg.span))
+                                .unwrap_or_else(|| substs.type_at(1).to_string());
+                            span_lint_and_sugg(
+                                cx,
+                                PTR_ARG,
+                                hir_ty.span,
+                                "using a reference to `Cow` is not recommended",
                                 "change this to",
-                                "&Path".into(),
+                                format!("&{}{}", mutability.prefix_str(), ty_name),
                                 Applicability::Unspecified,
                             );
-                            for (clonespan, suggestion) in spans {
-                                diag.span_suggestion_short(
-                                    clonespan,
-                                    &snippet_opt(cx, clonespan).map_or("change the call to".into(), |x| {
-                                        Cow::Owned(format!("change `{}` to", x))
-                                    }),
-                                    suggestion.into(),
-                                    Applicability::Unspecified,
-                                );
-                            }
+                            return None;
                         },
-                    );
-                }
-            },
-            sym::Cow => {
-                if_chain! {
-                    if let [ref bx] = *path.segments;
-                    if let Some(params) = bx.args;
-                    if !params.parenthesized;
-                    if let Some(inner) = params.args.iter().find_map(|arg| match arg {
-                        GenericArg::Type(ty) => Some(ty),
-                        _ => None,
+                        _ => return None,
+                    };
+                    return Some(PtrArg {
+                        idx: i,
+                        span: hir_ty.span,
+                        ty_did: adt.did,
+                        ty_name: name.ident.name,
+                        method_renames,
+                        ref_prefix: RefPrefix {
+                            lt: lt.name,
+                            mutability,
+                        },
+                        deref_ty,
+                        deref_assoc_items: deref_impl_id.map(|id| (id, cx.tcx.associated_items(id))),
                     });
-                    let replacement = snippet_opt(cx, inner.span);
-                    if let Some(r) = replacement;
-                    then {
-                        span_lint_and_sugg(
-                            cx,
-                            PTR_ARG,
-                            arg.span,
-                            "using a reference to `Cow` is not recommended",
-                            "change this to",
-                            "&".to_owned() + &r,
-                            Applicability::Unspecified,
-                        );
-                    }
                 }
-            },
-            _ => {},
-        }
-    }
+            }
+            None
+        })
+}
 
+fn check_mut_from_ref(cx: &LateContext<'_>, decl: &FnDecl<'_>) {
     if let FnRetTy::Return(ty) = decl.output {
         if let Some((out, Mutability::Mut, _)) = get_rptr_lm(ty) {
             let mut immutables = vec![];
-            for (_, ref mutbl, ref argspan) in decl
+            for (_, mutbl, argspan) in decl
                 .inputs
                 .iter()
                 .filter_map(get_rptr_lm)
                 .filter(|&(lt, _, _)| lt.name == out.name)
             {
-                if *mutbl == Mutability::Mut {
+                if mutbl == Mutability::Mut {
                     return;
                 }
-                immutables.push(*argspan);
+                immutables.push(argspan);
             }
             if immutables.is_empty() {
                 return;
@@ -413,24 +504,158 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, opt_body_id: Option<BodyId>
     }
 }
 
-fn get_only_generic_arg_snippet(cx: &LateContext<'_>, arg: &Ty<'_>) -> Option<String> {
-    if_chain! {
-        if let TyKind::Path(QPath::Resolved(_, path)) = walk_ptrs_hir_ty(arg).kind;
-        if let Some(&PathSegment{args: Some(parameters), ..}) = path.segments.last();
-        let types: Vec<_> = parameters.args.iter().filter_map(|arg| match arg {
-            GenericArg::Type(ty) => Some(ty),
-            _ => None,
-        }).collect();
-        if types.len() == 1;
-        then {
-            snippet_opt(cx, types[0].span)
-        } else {
-            None
+#[allow(clippy::too_many_lines)]
+fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &'tcx Body<'_>, args: &[PtrArg<'tcx>]) -> Vec<PtrArgResult> {
+    struct V<'cx, 'tcx> {
+        cx: &'cx LateContext<'tcx>,
+        /// Map from a local id to which argument it came from (index into `Self::args` and
+        /// `Self::results`)
+        bindings: HirIdMap<usize>,
+        /// The arguments being checked.
+        args: &'cx [PtrArg<'tcx>],
+        /// The results for each argument (len should match args.len)
+        results: Vec<PtrArgResult>,
+        /// The number of arguments which can't be linted. Used to return early.
+        skip_count: usize,
+    }
+    impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> {
+        type NestedFilter = nested_filter::OnlyBodies;
+        fn nested_visit_map(&mut self) -> Self::Map {
+            self.cx.tcx.hir()
+        }
+
+        fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
+
+        fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
+            if self.skip_count == self.args.len() {
+                return;
+            }
+
+            // Check if this is local we care about
+            let args_idx = match path_to_local(e).and_then(|id| self.bindings.get(&id)) {
+                Some(&i) => i,
+                None => return walk_expr(self, e),
+            };
+            let args = &self.args[args_idx];
+            let result = &mut self.results[args_idx];
+
+            // Helper function to handle early returns.
+            let mut set_skip_flag = || {
+                if result.skip {
+                    self.skip_count += 1;
+                }
+                result.skip = true;
+            };
+
+            match get_expr_use_or_unification_node(self.cx.tcx, e) {
+                Some((Node::Stmt(_), _)) => (),
+                Some((Node::Local(l), _)) => {
+                    // Only trace simple bindings. e.g `let x = y;`
+                    if let PatKind::Binding(BindingAnnotation::Unannotated, id, _, None) = l.pat.kind {
+                        self.bindings.insert(id, args_idx);
+                    } else {
+                        set_skip_flag();
+                    }
+                },
+                Some((Node::Expr(e), child_id)) => match e.kind {
+                    ExprKind::Call(f, expr_args) => {
+                        let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0);
+                        if expr_sig(self.cx, f)
+                            .map(|sig| sig.input(i).skip_binder().peel_refs())
+                            .map_or(true, |ty| match *ty.kind() {
+                                ty::Param(_) => true,
+                                ty::Adt(def, _) => def.did == args.ty_did,
+                                _ => false,
+                            })
+                        {
+                            // Passed to a function taking the non-dereferenced type.
+                            set_skip_flag();
+                        }
+                    },
+                    ExprKind::MethodCall(name, expr_args @ [self_arg, ..], _) => {
+                        let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0);
+                        if i == 0 {
+                            // Check if the method can be renamed.
+                            let name = name.ident.as_str();
+                            if let Some((_, replacement)) = args.method_renames.iter().find(|&&(x, _)| x == name) {
+                                result.replacements.push(PtrArgReplacement {
+                                    expr_span: e.span,
+                                    self_span: self_arg.span,
+                                    replacement,
+                                });
+                                return;
+                            }
+                        }
+
+                        let id = if let Some(x) = self.cx.typeck_results().type_dependent_def_id(e.hir_id) {
+                            x
+                        } else {
+                            set_skip_flag();
+                            return;
+                        };
+
+                        match *self.cx.tcx.fn_sig(id).skip_binder().inputs()[i].peel_refs().kind() {
+                            ty::Param(_) => {
+                                set_skip_flag();
+                            },
+                            // If the types match check for methods which exist on both types. e.g. `Vec::len` and
+                            // `slice::len`
+                            ty::Adt(def, _)
+                                if def.did == args.ty_did
+                                    && (i != 0
+                                        || self.cx.tcx.trait_of_item(id).is_some()
+                                        || !args.deref_assoc_items.map_or(false, |(id, items)| {
+                                            items
+                                                .find_by_name_and_kind(self.cx.tcx, name.ident, AssocKind::Fn, id)
+                                                .is_some()
+                                        })) =>
+                            {
+                                set_skip_flag();
+                            },
+                            _ => (),
+                        }
+                    },
+                    // Indexing is fine for currently supported types.
+                    ExprKind::Index(e, _) if e.hir_id == child_id => (),
+                    _ => set_skip_flag(),
+                },
+                _ => set_skip_flag(),
+            }
         }
     }
+
+    let mut skip_count = 0;
+    let mut results = args.iter().map(|_| PtrArgResult::default()).collect::<Vec<_>>();
+    let mut v = V {
+        cx,
+        bindings: args
+            .iter()
+            .enumerate()
+            .filter_map(|(i, arg)| {
+                let param = &body.params[arg.idx];
+                match param.pat.kind {
+                    PatKind::Binding(BindingAnnotation::Unannotated, id, _, None)
+                        if !is_lint_allowed(cx, PTR_ARG, param.hir_id) =>
+                    {
+                        Some((id, i))
+                    },
+                    _ => {
+                        skip_count += 1;
+                        results[arg.idx].skip = true;
+                        None
+                    },
+                }
+            })
+            .collect(),
+        args,
+        results,
+        skip_count,
+    };
+    v.visit_expr(&body.value);
+    v.results
 }
 
-fn get_rptr_lm<'tcx>(ty: &'tcx Ty<'tcx>) -> Option<(&'tcx Lifetime, Mutability, Span)> {
+fn get_rptr_lm<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> Option<(&'tcx Lifetime, Mutability, Span)> {
     if let TyKind::Rptr(ref lt, ref m) = ty.kind {
         Some((lt, m.mutbl, ty.span))
     } else {
diff --git a/src/tools/clippy/clippy_lints/src/reference.rs b/src/tools/clippy/clippy_lints/src/reference.rs
index b2448372370..811a7bb9c15 100644
--- a/src/tools/clippy/clippy_lints/src/reference.rs
+++ b/src/tools/clippy/clippy_lints/src/reference.rs
@@ -1,6 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::{snippet_opt, snippet_with_applicability};
-use clippy_utils::sugg::Sugg;
 use if_chain::if_chain;
 use rustc_ast::ast::{Expr, ExprKind, Mutability, UnOp};
 use rustc_errors::Applicability;
@@ -104,59 +103,3 @@ impl EarlyLintPass for DerefAddrOf {
         }
     }
 }
-
-declare_clippy_lint! {
-    /// ### What it does
-    /// Checks for references in expressions that use
-    /// auto dereference.
-    ///
-    /// ### Why is this bad?
-    /// The reference is a no-op and is automatically
-    /// dereferenced by the compiler and makes the code less clear.
-    ///
-    /// ### Example
-    /// ```rust
-    /// struct Point(u32, u32);
-    /// let point = Point(30, 20);
-    /// let x = (&point).0;
-    /// ```
-    /// Use instead:
-    /// ```rust
-    /// # struct Point(u32, u32);
-    /// # let point = Point(30, 20);
-    /// let x = point.0;
-    /// ```
-    #[clippy::version = "pre 1.29.0"]
-    pub REF_IN_DEREF,
-    complexity,
-    "Use of reference in auto dereference expression."
-}
-
-declare_lint_pass!(RefInDeref => [REF_IN_DEREF]);
-
-impl EarlyLintPass for RefInDeref {
-    fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
-        if_chain! {
-            if let ExprKind::Field(ref object, _) = e.kind;
-            if let ExprKind::Paren(ref parened) = object.kind;
-            if let ExprKind::AddrOf(_, _, ref inner) = parened.kind;
-            then {
-                let applicability = if inner.span.from_expansion() {
-                    Applicability::MaybeIncorrect
-                } else {
-                    Applicability::MachineApplicable
-                };
-                let sugg = Sugg::ast(cx, inner, "_").maybe_par();
-                span_lint_and_sugg(
-                    cx,
-                    REF_IN_DEREF,
-                    object.span,
-                    "creating a reference that is immediately dereferenced",
-                    "try this",
-                    sugg.to_string(),
-                    applicability,
-                );
-            }
-        }
-    }
-}
diff --git a/src/tools/clippy/clippy_lints/src/trait_bounds.rs b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
index 6369aafe3f9..5257f5302cd 100644
--- a/src/tools/clippy/clippy_lints/src/trait_bounds.rs
+++ b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
@@ -3,7 +3,7 @@ use clippy_utils::source::{snippet, snippet_with_applicability};
 use clippy_utils::{SpanlessEq, SpanlessHash};
 use core::hash::{Hash, Hasher};
 use if_chain::if_chain;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::unhash::UnhashMap;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
@@ -91,7 +91,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
 
     fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'tcx>) {
         let Generics { where_clause, .. } = &item.generics;
-        let mut self_bounds_set = FxHashSet::default();
+        let mut self_bounds_map = FxHashMap::default();
 
         for predicate in where_clause.predicates {
             if_chain! {
@@ -108,27 +108,29 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
                         )
                     ) = cx.tcx.hir().get_if_local(*def_id);
                 then {
-                    if self_bounds_set.is_empty() {
+                    if self_bounds_map.is_empty() {
                         for bound in self_bounds.iter() {
-                            let Some((self_res, _)) = get_trait_res_span_from_bound(bound) else { continue };
-                            self_bounds_set.insert(self_res);
+                            let Some((self_res, self_segments, _)) = get_trait_info_from_bound(bound) else { continue };
+                            self_bounds_map.insert(self_res, self_segments);
                         }
                     }
 
                     bound_predicate
                         .bounds
                         .iter()
-                        .filter_map(get_trait_res_span_from_bound)
-                        .for_each(|(trait_item_res, span)| {
-                            if self_bounds_set.get(&trait_item_res).is_some() {
-                                span_lint_and_help(
-                                    cx,
-                                    TRAIT_DUPLICATION_IN_BOUNDS,
-                                    span,
-                                    "this trait bound is already specified in trait declaration",
-                                    None,
-                                    "consider removing this trait bound",
-                                );
+                        .filter_map(get_trait_info_from_bound)
+                        .for_each(|(trait_item_res, trait_item_segments, span)| {
+                            if let Some(self_segments) = self_bounds_map.get(&trait_item_res) {
+                                if SpanlessEq::new(cx).eq_path_segments(self_segments, trait_item_segments) {
+                                    span_lint_and_help(
+                                        cx,
+                                        TRAIT_DUPLICATION_IN_BOUNDS,
+                                        span,
+                                        "this trait bound is already specified in trait declaration",
+                                        None,
+                                        "consider removing this trait bound",
+                                    );
+                                }
                             }
                         });
                 }
@@ -137,14 +139,6 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
     }
 }
 
-fn get_trait_res_span_from_bound(bound: &GenericBound<'_>) -> Option<(Res, Span)> {
-    if let GenericBound::Trait(t, _) = bound {
-        Some((t.trait_ref.path.res, t.span))
-    } else {
-        None
-    }
-}
-
 impl TraitBounds {
     fn check_type_repetition<'tcx>(self, cx: &LateContext<'tcx>, gen: &'tcx Generics<'_>) {
         struct SpanlessTy<'cx, 'tcx> {
@@ -231,7 +225,7 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
             let res = param
                 .bounds
                 .iter()
-                .filter_map(get_trait_res_span_from_bound)
+                .filter_map(get_trait_info_from_bound)
                 .collect::<Vec<_>>();
             map.insert(*ident, res);
         }
@@ -245,10 +239,10 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
             if let Some(segment) = segments.first();
             if let Some(trait_resolutions_direct) = map.get(&segment.ident);
             then {
-                for (res_where, _) in bound_predicate.bounds.iter().filter_map(get_trait_res_span_from_bound) {
-                    if let Some((_, span_direct)) = trait_resolutions_direct
+                for (res_where, _,  _) in bound_predicate.bounds.iter().filter_map(get_trait_info_from_bound) {
+                    if let Some((_, _, span_direct)) = trait_resolutions_direct
                                                 .iter()
-                                                .find(|(res_direct, _)| *res_direct == res_where) {
+                                                .find(|(res_direct, _, _)| *res_direct == res_where) {
                         span_lint_and_help(
                             cx,
                             TRAIT_DUPLICATION_IN_BOUNDS,
@@ -263,3 +257,11 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
         }
     }
 }
+
+fn get_trait_info_from_bound<'a>(bound: &'a GenericBound<'_>) -> Option<(Res, &'a [PathSegment<'a>], Span)> {
+    if let GenericBound::Trait(t, _) = bound {
+        Some((t.trait_ref.path.res, t.trait_ref.path.segments, t.span))
+    } else {
+        None
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs b/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
index 141f2604872..eee1229e1ef 100644
--- a/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
+++ b/src/tools/clippy/clippy_lints/src/unit_return_expecting_ord.rs
@@ -98,10 +98,11 @@ fn get_args_to_check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Ve
                         if trait_pred.self_ty() == inp;
                         if let Some(return_ty_pred) = get_projection_pred(cx, generics, *trait_pred);
                         then {
-                            if ord_preds.iter().any(|ord| Some(ord.self_ty()) ==
-                            return_ty_pred.term.ty()) {
+                            if ord_preds.iter().any(|ord| Some(ord.self_ty()) == return_ty_pred.term.ty()) {
                                 args_to_check.push((i, "Ord".to_string()));
-                            } else if partial_ord_preds.iter().any(|pord| pord.self_ty() == return_ty_pred.term.ty().unwrap()) {
+                            } else if partial_ord_preds.iter().any(|pord| {
+                                pord.self_ty() == return_ty_pred.term.ty().unwrap()
+                            }) {
                                 args_to_check.push((i, "PartialOrd".to_string()));
                             }
                         }
diff --git a/src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs b/src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs
index 0bd151fed91..1d4fe9cfd3c 100644
--- a/src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs
+++ b/src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs
@@ -291,7 +291,7 @@ fn transform_with_focus_on_idx(alternatives: &mut Vec<P<Pat>>, focus_idx: usize)
 fn extend_with_struct_pat(
     qself1: &Option<ast::QSelf>,
     path1: &ast::Path,
-    fps1: &mut Vec<ast::PatField>,
+    fps1: &mut [ast::PatField],
     rest1: bool,
     start: usize,
     alternatives: &mut Vec<P<Pat>>,
@@ -332,7 +332,7 @@ fn extend_with_struct_pat(
 /// while also requiring `ps1[..n] ~ ps2[..n]` (pre) and `ps1[n + 1..] ~ ps2[n + 1..]` (post),
 /// where `~` denotes semantic equality.
 fn extend_with_matching_product(
-    targets: &mut Vec<P<Pat>>,
+    targets: &mut [P<Pat>],
     start: usize,
     alternatives: &mut Vec<P<Pat>>,
     predicate: impl Fn(&PatKind, &[P<Pat>], usize) -> bool,
diff --git a/src/tools/clippy/clippy_lints/src/utils/conf.rs b/src/tools/clippy/clippy_lints/src/utils/conf.rs
index d6deb50cc90..c9d99617c1e 100644
--- a/src/tools/clippy/clippy_lints/src/utils/conf.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/conf.rs
@@ -156,7 +156,7 @@ define_Conf! {
     ///
     /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
-    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE.
+    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE, MAP_CLONE, BORROW_AS_PTR, MANUAL_BITS.
     ///
     /// The minimum rust version that the project supports
     (msrv: Option<String> = None),
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
index ec1b5a499d4..f170ff69154 100644
--- a/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
@@ -23,6 +23,7 @@ use rustc_hir::{
     UnOp,
 };
 use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
+use rustc_middle::hir::nested_filter;
 use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty;
 use rustc_semver::RustcVersion;
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
index 512c39389c1..3547f0b4e0a 100644
--- a/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
@@ -19,7 +19,9 @@ use rustc_hir::{
     self as hir, def::DefKind, intravisit, intravisit::Visitor, ExprKind, Item, ItemKind, Mutability, QPath,
 };
 use rustc_lint::{CheckLintNameResult, LateContext, LateLintPass, LintContext, LintId};
+use rustc_middle::hir::nested_filter;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::symbol::Ident;
 use rustc_span::{sym, Loc, Span, Symbol};
 use serde::{ser::SerializeStruct, Serialize, Serializer};
 use std::collections::BinaryHeap;
@@ -578,9 +580,11 @@ fn get_lint_group_and_level_or_lint(
     lint_name: &str,
     item: &Item<'_>,
 ) -> Option<(String, &'static str)> {
-    let result = cx
-        .lint_store
-        .check_lint_name(lint_name, Some(sym::clippy), &[]);
+    let result = cx.lint_store.check_lint_name(
+        lint_name,
+        Some(sym::clippy),
+        &[Ident::with_dummy_span(sym::clippy)].into_iter().collect(),
+    );
     if let CheckLintNameResult::Tool(Ok(lint_lst)) = result {
         if let Some(group) = get_lint_group(cx, lint_lst[0]) {
             if EXCLUDED_LINT_GROUPS.contains(&group.as_str()) {
diff --git a/src/tools/clippy/clippy_utils/src/ast_utils.rs b/src/tools/clippy/clippy_utils/src/ast_utils.rs
index 604c95d2bc8..3f4043ad052 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils.rs
@@ -646,11 +646,11 @@ pub fn eq_generic_bound(l: &GenericBound, r: &GenericBound) -> bool {
 }
 
 fn eq_term(l: &Term, r: &Term) -> bool {
-  match (l, r) {
-    (Term::Ty(l), Term::Ty(r)) => eq_ty(l,r),
-    (Term::Const(l), Term::Const(r)) => eq_anon_const(l,r),
-    _ => false,
-  }
+    match (l, r) {
+        (Term::Ty(l), Term::Ty(r)) => eq_ty(l, r),
+        (Term::Const(l), Term::Const(r)) => eq_anon_const(l, r),
+        _ => false,
+    }
 }
 
 pub fn eq_assoc_constraint(l: &AssocConstraint, r: &AssocConstraint) -> bool {
diff --git a/src/tools/clippy/clippy_utils/src/lib.rs b/src/tools/clippy/clippy_utils/src/lib.rs
index 9233903e98a..a2f1f469651 100644
--- a/src/tools/clippy/clippy_utils/src/lib.rs
+++ b/src/tools/clippy/clippy_utils/src/lib.rs
@@ -1827,7 +1827,8 @@ pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool
 }
 
 /// Gets the node where an expression is either used, or it's type is unified with another branch.
-pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<Node<'tcx>> {
+/// Returns both the node and the `HirId` of the closest child node.
+pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>) -> Option<(Node<'tcx>, HirId)> {
     let mut child_id = expr.hir_id;
     let mut iter = tcx.hir().parent_iter(child_id);
     loop {
@@ -1839,9 +1840,9 @@ pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>
                 ExprKind::Match(_, [arm], _) if arm.hir_id == child_id => child_id = expr.hir_id,
                 ExprKind::Block(..) | ExprKind::DropTemps(_) => child_id = expr.hir_id,
                 ExprKind::If(_, then_expr, None) if then_expr.hir_id == child_id => break None,
-                _ => break Some(Node::Expr(expr)),
+                _ => break Some((Node::Expr(expr), child_id)),
             },
-            Some((_, node)) => break Some(node),
+            Some((_, node)) => break Some((node, child_id)),
         }
     }
 }
@@ -1850,18 +1851,21 @@ pub fn get_expr_use_or_unification_node<'tcx>(tcx: TyCtxt<'tcx>, expr: &Expr<'_>
 pub fn is_expr_used_or_unified(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> bool {
     !matches!(
         get_expr_use_or_unification_node(tcx, expr),
-        None | Some(Node::Stmt(Stmt {
-            kind: StmtKind::Expr(_)
-                | StmtKind::Semi(_)
-                | StmtKind::Local(Local {
-                    pat: Pat {
-                        kind: PatKind::Wild,
+        None | Some((
+            Node::Stmt(Stmt {
+                kind: StmtKind::Expr(_)
+                    | StmtKind::Semi(_)
+                    | StmtKind::Local(Local {
+                        pat: Pat {
+                            kind: PatKind::Wild,
+                            ..
+                        },
                         ..
-                    },
-                    ..
-                }),
-            ..
-        }))
+                    }),
+                ..
+            }),
+            _
+        ))
     )
 }
 
diff --git a/src/tools/clippy/clippy_utils/src/numeric_literal.rs b/src/tools/clippy/clippy_utils/src/numeric_literal.rs
index 68dd1b29845..908ff822712 100644
--- a/src/tools/clippy/clippy_utils/src/numeric_literal.rs
+++ b/src/tools/clippy/clippy_utils/src/numeric_literal.rs
@@ -51,7 +51,14 @@ impl<'a> NumericLiteral<'a> {
     }
 
     pub fn from_lit_kind(src: &'a str, lit_kind: &LitKind) -> Option<NumericLiteral<'a>> {
-        if lit_kind.is_numeric() && src.chars().next().map_or(false, |c| c.is_digit(10)) {
+        let unsigned_src = src.strip_prefix('-').map_or(src, |s| s);
+        if lit_kind.is_numeric()
+            && unsigned_src
+                .trim_start()
+                .chars()
+                .next()
+                .map_or(false, |c| c.is_digit(10))
+        {
             let (unsuffixed, suffix) = split_suffix(src, lit_kind);
             let float = matches!(lit_kind, LitKind::Float(..));
             Some(NumericLiteral::new(unsuffixed, suffix, float))
diff --git a/src/tools/clippy/clippy_utils/src/sugg.rs b/src/tools/clippy/clippy_utils/src/sugg.rs
index 48525f9a572..fa63ddff253 100644
--- a/src/tools/clippy/clippy_utils/src/sugg.rs
+++ b/src/tools/clippy/clippy_utils/src/sugg.rs
@@ -386,7 +386,7 @@ fn binop_to_string(op: AssocOp, lhs: &str, rhs: &str) -> String {
 }
 
 /// Return `true` if `sugg` is enclosed in parenthesis.
-fn has_enclosing_paren(sugg: impl AsRef<str>) -> bool {
+pub fn has_enclosing_paren(sugg: impl AsRef<str>) -> bool {
     let mut chars = sugg.as_ref().chars();
     if chars.next() == Some('(') {
         let mut depth = 1;
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index f109b7845b4..d057da73302 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -5,19 +5,22 @@
 use rustc_ast::ast::Mutability;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir as hir;
+use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::DefId;
-use rustc_hir::{TyKind, Unsafety};
+use rustc_hir::{Expr, TyKind, Unsafety};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
-use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
-use rustc_middle::ty::{self, AdtDef, IntTy, Predicate, Ty, TyCtxt, TypeFoldable, UintTy};
+use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
+use rustc_middle::ty::{
+    self, AdtDef, Binder, FnSig, IntTy, Predicate, PredicateKind, Ty, TyCtxt, TypeFoldable, UintTy,
+};
 use rustc_span::symbol::Ident;
 use rustc_span::{sym, Span, Symbol, DUMMY_SP};
 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};
+use crate::{expr_path_res, match_def_path, must_use_attr};
 
 // Checks if the given type implements copy.
 pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
@@ -410,3 +413,105 @@ pub fn all_predicates_of(tcx: TyCtxt<'_>, id: DefId) -> impl Iterator<Item = &(P
     })
     .flatten()
 }
+
+/// A signature for a function like type.
+#[derive(Clone, Copy)]
+pub enum ExprFnSig<'tcx> {
+    Sig(Binder<'tcx, FnSig<'tcx>>),
+    Closure(Binder<'tcx, FnSig<'tcx>>),
+    Trait(Binder<'tcx, Ty<'tcx>>, Option<Binder<'tcx, Ty<'tcx>>>),
+}
+impl<'tcx> ExprFnSig<'tcx> {
+    /// Gets the argument type at the given offset.
+    pub fn input(self, i: usize) -> Binder<'tcx, Ty<'tcx>> {
+        match self {
+            Self::Sig(sig) => sig.input(i),
+            Self::Closure(sig) => sig.input(0).map_bound(|ty| ty.tuple_element_ty(i).unwrap()),
+            Self::Trait(inputs, _) => inputs.map_bound(|ty| ty.tuple_element_ty(i).unwrap()),
+        }
+    }
+
+    /// Gets the result type, if one could be found. Note that the result type of a trait may not be
+    /// specified.
+    pub fn output(self) -> Option<Binder<'tcx, Ty<'tcx>>> {
+        match self {
+            Self::Sig(sig) | Self::Closure(sig) => Some(sig.output()),
+            Self::Trait(_, output) => output,
+        }
+    }
+}
+
+/// If the expression is function like, get the signature for it.
+pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnSig<'tcx>> {
+    if let Res::Def(DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::AssocFn, id) = expr_path_res(cx, expr) {
+        Some(ExprFnSig::Sig(cx.tcx.fn_sig(id)))
+    } else {
+        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::FnPtr(sig) => Some(ExprFnSig::Sig(sig)),
+            ty::Dynamic(bounds, _) => {
+                let lang_items = cx.tcx.lang_items();
+                match bounds.principal() {
+                    Some(bound)
+                        if Some(bound.def_id()) == lang_items.fn_trait()
+                            || Some(bound.def_id()) == lang_items.fn_once_trait()
+                            || Some(bound.def_id()) == lang_items.fn_mut_trait() =>
+                    {
+                        let output = bounds
+                            .projection_bounds()
+                            .find(|p| lang_items.fn_once_output().map_or(false, |id| id == p.item_def_id()))
+                            .map(|p| p.map_bound(|p| p.term.ty().expect("return type was a const")));
+                        Some(ExprFnSig::Trait(bound.map_bound(|b| b.substs.type_at(0)), output))
+                    },
+                    _ => None,
+                }
+            },
+            ty::Param(_) | ty::Projection(..) => {
+                let mut inputs = None;
+                let mut output = None;
+                let lang_items = cx.tcx.lang_items();
+
+                for (pred, _) in all_predicates_of(cx.tcx, cx.typeck_results().hir_owner.to_def_id()) {
+                    let mut is_input = false;
+                    if let Some(ty) = pred
+                        .kind()
+                        .map_bound(|pred| match pred {
+                            PredicateKind::Trait(p)
+                                if (lang_items.fn_trait() == Some(p.def_id())
+                                    || lang_items.fn_mut_trait() == Some(p.def_id())
+                                    || lang_items.fn_once_trait() == Some(p.def_id()))
+                                    && p.self_ty() == ty =>
+                            {
+                                is_input = true;
+                                Some(p.trait_ref.substs.type_at(1))
+                            },
+                            PredicateKind::Projection(p)
+                                if Some(p.projection_ty.item_def_id) == lang_items.fn_once_output()
+                                    && p.projection_ty.self_ty() == ty =>
+                            {
+                                is_input = false;
+                                p.term.ty()
+                            },
+                            _ => None,
+                        })
+                        .transpose()
+                    {
+                        if is_input && inputs.is_none() {
+                            inputs = Some(ty);
+                        } else if !is_input && output.is_none() {
+                            output = Some(ty);
+                        } else {
+                            // Multiple different fn trait impls. Is this even allowed?
+                            return None;
+                        }
+                    }
+                }
+
+                inputs.map(|ty| ExprFnSig::Trait(ty, output))
+            },
+            _ => None,
+        }
+    }
+}
diff --git a/src/tools/clippy/rust-toolchain b/src/tools/clippy/rust-toolchain
index e6a58e92072..e23dc73ab08 100644
--- a/src/tools/clippy/rust-toolchain
+++ b/src/tools/clippy/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2022-01-13"
+channel = "nightly-2022-01-27"
 components = ["cargo", "llvm-tools-preview", "rust-src", "rust-std", "rustc", "rustc-dev", "rustfmt"]
diff --git a/src/tools/clippy/src/driver.rs b/src/tools/clippy/src/driver.rs
index a8aa3a76abc..8f8f1140a3d 100644
--- a/src/tools/clippy/src/driver.rs
+++ b/src/tools/clippy/src/driver.rs
@@ -331,11 +331,10 @@ pub fn main() {
         // - IF Clippy is run on the main crate, not on deps (`!cap_lints_allow`) THEN
         //    - IF `--no-deps` is not set (`!no_deps`) OR
         //    - IF `--no-deps` is set and Clippy is run on the specified primary package
-        let clippy_tests_set = env::var("__CLIPPY_INTERNAL_TESTS").map_or(false, |val| val == "true");
         let cap_lints_allow = arg_value(&orig_args, "--cap-lints", |val| val == "allow").is_some();
         let in_primary_package = env::var("CARGO_PRIMARY_PACKAGE").is_ok();
 
-        let clippy_enabled = clippy_tests_set || (!cap_lints_allow && (!no_deps || in_primary_package));
+        let clippy_enabled = !cap_lints_allow && (!no_deps || in_primary_package);
         if clippy_enabled {
             args.extend(clippy_args);
         }
diff --git a/src/tools/clippy/tests/compile-test.rs b/src/tools/clippy/tests/compile-test.rs
index 531890c863f..6505028db9f 100644
--- a/src/tools/clippy/tests/compile-test.rs
+++ b/src/tools/clippy/tests/compile-test.rs
@@ -328,15 +328,9 @@ fn run_ui_cargo(config: &mut compiletest::Config) {
     }
 }
 
-fn prepare_env() {
-    set_var("CLIPPY_DISABLE_DOCS_LINKS", "true");
-    set_var("__CLIPPY_INTERNAL_TESTS", "true");
-    //set_var("RUST_BACKTRACE", "0");
-}
-
 #[test]
 fn compile_test() {
-    prepare_env();
+    set_var("CLIPPY_DISABLE_DOCS_LINKS", "true");
     let mut config = default_config();
     run_ui(&mut config);
     run_ui_test(&mut config);
diff --git a/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.rs b/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.rs
index 8e104926524..1e3ec123a3c 100644
--- a/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.rs
+++ b/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.rs
@@ -1,6 +1,7 @@
-#![allow(clippy::redundant_clone)]
-#![warn(clippy::manual_non_exhaustive)]
+#![allow(clippy::redundant_clone, clippy::unnecessary_operation)]
+#![warn(clippy::manual_non_exhaustive, clippy::borrow_as_ptr, clippy::manual_bits)]
 
+use std::mem::{size_of, size_of_val};
 use std::ops::Deref;
 
 mod enums {
@@ -68,6 +69,24 @@ fn check_index_refutable_slice() {
     }
 }
 
+fn map_clone_suggest_copied() {
+    // This should still trigger the lint but suggest `cloned()` instead of `copied()`
+    let _: Option<u64> = Some(&16).map(|b| *b);
+}
+
+fn borrow_as_ptr() {
+    let val = 1;
+    let _p = &val as *const i32;
+
+    let mut val_mut = 1;
+    let _p_mut = &mut val_mut as *mut i32;
+}
+
+fn manual_bits() {
+    size_of::<i8>() * 8;
+    size_of_val(&0u32) * 8;
+}
+
 fn main() {
     option_as_ref_deref();
     match_like_matches();
@@ -75,4 +94,5 @@ fn main() {
     match_same_arms2();
     manual_strip_msrv();
     check_index_refutable_slice();
+    borrow_as_ptr();
 }
diff --git a/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.stderr b/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.stderr
new file mode 100644
index 00000000000..a1e7361c0cb
--- /dev/null
+++ b/src/tools/clippy/tests/ui-toml/min_rust_version/min_rust_version.stderr
@@ -0,0 +1,10 @@
+error: you are using an explicit closure for copying elements
+  --> $DIR/min_rust_version.rs:74:26
+   |
+LL |     let _: Option<u64> = Some(&16).map(|b| *b);
+   |                          ^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `Some(&16).cloned()`
+   |
+   = note: `-D clippy::map-clone` implied by `-D warnings`
+
+error: aborting due to previous error
+
diff --git a/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.rs b/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.rs
index 4327f12c37c..eefeb1decb6 100644
--- a/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.rs
+++ b/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.rs
@@ -1,9 +1,5 @@
 #![warn(clippy::borrow_interior_mutable_const)]
-#![allow(
-    clippy::declare_interior_mutable_const,
-    clippy::ref_in_deref,
-    clippy::needless_borrow
-)]
+#![allow(clippy::declare_interior_mutable_const, clippy::needless_borrow)]
 #![allow(const_item_mutation)]
 
 use std::borrow::Cow;
diff --git a/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.stderr b/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.stderr
index f146b97cf61..9a908cf30e9 100644
--- a/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.stderr
+++ b/src/tools/clippy/tests/ui/borrow_interior_mutable_const/others.stderr
@@ -1,5 +1,5 @@
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:58:5
+  --> $DIR/others.rs:54:5
    |
 LL |     ATOMIC.store(1, Ordering::SeqCst); //~ ERROR interior mutability
    |     ^^^^^^
@@ -8,7 +8,7 @@ LL |     ATOMIC.store(1, Ordering::SeqCst); //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:59:16
+  --> $DIR/others.rs:55:16
    |
 LL |     assert_eq!(ATOMIC.load(Ordering::SeqCst), 5); //~ ERROR interior mutability
    |                ^^^^^^
@@ -16,7 +16,7 @@ LL |     assert_eq!(ATOMIC.load(Ordering::SeqCst), 5); //~ ERROR interior mutabi
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:62:22
+  --> $DIR/others.rs:58:22
    |
 LL |     let _once_ref = &ONCE_INIT; //~ ERROR interior mutability
    |                      ^^^^^^^^^
@@ -24,7 +24,7 @@ LL |     let _once_ref = &ONCE_INIT; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:63:25
+  --> $DIR/others.rs:59:25
    |
 LL |     let _once_ref_2 = &&ONCE_INIT; //~ ERROR interior mutability
    |                         ^^^^^^^^^
@@ -32,7 +32,7 @@ LL |     let _once_ref_2 = &&ONCE_INIT; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:64:27
+  --> $DIR/others.rs:60:27
    |
 LL |     let _once_ref_4 = &&&&ONCE_INIT; //~ ERROR interior mutability
    |                           ^^^^^^^^^
@@ -40,7 +40,7 @@ LL |     let _once_ref_4 = &&&&ONCE_INIT; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:65:26
+  --> $DIR/others.rs:61:26
    |
 LL |     let _once_mut = &mut ONCE_INIT; //~ ERROR interior mutability
    |                          ^^^^^^^^^
@@ -48,7 +48,7 @@ LL |     let _once_mut = &mut ONCE_INIT; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:76:14
+  --> $DIR/others.rs:72:14
    |
 LL |     let _ = &ATOMIC_TUPLE; //~ ERROR interior mutability
    |              ^^^^^^^^^^^^
@@ -56,7 +56,7 @@ LL |     let _ = &ATOMIC_TUPLE; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:77:14
+  --> $DIR/others.rs:73:14
    |
 LL |     let _ = &ATOMIC_TUPLE.0; //~ ERROR interior mutability
    |              ^^^^^^^^^^^^
@@ -64,7 +64,7 @@ LL |     let _ = &ATOMIC_TUPLE.0; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:78:19
+  --> $DIR/others.rs:74:19
    |
 LL |     let _ = &(&&&&ATOMIC_TUPLE).0; //~ ERROR interior mutability
    |                   ^^^^^^^^^^^^
@@ -72,7 +72,7 @@ LL |     let _ = &(&&&&ATOMIC_TUPLE).0; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:79:14
+  --> $DIR/others.rs:75:14
    |
 LL |     let _ = &ATOMIC_TUPLE.0[0]; //~ ERROR interior mutability
    |              ^^^^^^^^^^^^
@@ -80,7 +80,7 @@ LL |     let _ = &ATOMIC_TUPLE.0[0]; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:80:13
+  --> $DIR/others.rs:76:13
    |
 LL |     let _ = ATOMIC_TUPLE.0[0].load(Ordering::SeqCst); //~ ERROR interior mutability
    |             ^^^^^^^^^^^^
@@ -88,7 +88,7 @@ LL |     let _ = ATOMIC_TUPLE.0[0].load(Ordering::SeqCst); //~ ERROR interior mu
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:86:13
+  --> $DIR/others.rs:82:13
    |
 LL |     let _ = ATOMIC_TUPLE.0[0]; //~ ERROR interior mutability
    |             ^^^^^^^^^^^^
@@ -96,7 +96,7 @@ LL |     let _ = ATOMIC_TUPLE.0[0]; //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:91:5
+  --> $DIR/others.rs:87:5
    |
 LL |     CELL.set(2); //~ ERROR interior mutability
    |     ^^^^
@@ -104,7 +104,7 @@ LL |     CELL.set(2); //~ ERROR interior mutability
    = help: assign this const to a local or static variable, and use the variable here
 
 error: a `const` item with interior mutability should not be borrowed
-  --> $DIR/others.rs:92:16
+  --> $DIR/others.rs:88:16
    |
 LL |     assert_eq!(CELL.get(), 6); //~ ERROR interior mutability
    |                ^^^^
diff --git a/src/tools/clippy/tests/ui/bytecount.rs b/src/tools/clippy/tests/ui/bytecount.rs
index c724ee21be3..d3ad26921bf 100644
--- a/src/tools/clippy/tests/ui/bytecount.rs
+++ b/src/tools/clippy/tests/ui/bytecount.rs
@@ -1,3 +1,5 @@
+#![allow(clippy::needless_borrow)]
+
 #[deny(clippy::naive_bytecount)]
 fn main() {
     let x = vec![0_u8; 16];
diff --git a/src/tools/clippy/tests/ui/bytecount.stderr b/src/tools/clippy/tests/ui/bytecount.stderr
index 1dc37fc8b25..68d838c1f82 100644
--- a/src/tools/clippy/tests/ui/bytecount.stderr
+++ b/src/tools/clippy/tests/ui/bytecount.stderr
@@ -1,23 +1,23 @@
 error: you appear to be counting bytes the naive way
-  --> $DIR/bytecount.rs:5:13
+  --> $DIR/bytecount.rs:7:13
    |
 LL |     let _ = x.iter().filter(|&&a| a == 0).count(); // naive byte count
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using the bytecount crate: `bytecount::count(x, 0)`
    |
 note: the lint level is defined here
-  --> $DIR/bytecount.rs:1:8
+  --> $DIR/bytecount.rs:3:8
    |
 LL | #[deny(clippy::naive_bytecount)]
    |        ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: you appear to be counting bytes the naive way
-  --> $DIR/bytecount.rs:7:13
+  --> $DIR/bytecount.rs:9:13
    |
 LL |     let _ = (&x[..]).iter().filter(|&a| *a == 0).count(); // naive byte count
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using the bytecount crate: `bytecount::count((&x[..]), 0)`
 
 error: you appear to be counting bytes the naive way
-  --> $DIR/bytecount.rs:19:13
+  --> $DIR/bytecount.rs:21:13
    |
 LL |     let _ = x.iter().filter(|a| b + 1 == **a).count(); // naive byte count
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using the bytecount crate: `bytecount::count(x, b + 1)`
diff --git a/src/tools/clippy/tests/ui/clone_on_copy.fixed b/src/tools/clippy/tests/ui/clone_on_copy.fixed
index 8d43f64768d..dc062762604 100644
--- a/src/tools/clippy/tests/ui/clone_on_copy.fixed
+++ b/src/tools/clippy/tests/ui/clone_on_copy.fixed
@@ -7,7 +7,8 @@
     clippy::no_effect,
     clippy::unnecessary_operation,
     clippy::vec_init_then_push,
-    clippy::toplevel_ref_arg
+    clippy::toplevel_ref_arg,
+    clippy::needless_borrow
 )]
 
 use std::cell::RefCell;
diff --git a/src/tools/clippy/tests/ui/clone_on_copy.rs b/src/tools/clippy/tests/ui/clone_on_copy.rs
index f15501f7184..8c39d0d55dd 100644
--- a/src/tools/clippy/tests/ui/clone_on_copy.rs
+++ b/src/tools/clippy/tests/ui/clone_on_copy.rs
@@ -7,7 +7,8 @@
     clippy::no_effect,
     clippy::unnecessary_operation,
     clippy::vec_init_then_push,
-    clippy::toplevel_ref_arg
+    clippy::toplevel_ref_arg,
+    clippy::needless_borrow
 )]
 
 use std::cell::RefCell;
diff --git a/src/tools/clippy/tests/ui/clone_on_copy.stderr b/src/tools/clippy/tests/ui/clone_on_copy.stderr
index e7d28b4320b..861543d0aa9 100644
--- a/src/tools/clippy/tests/ui/clone_on_copy.stderr
+++ b/src/tools/clippy/tests/ui/clone_on_copy.stderr
@@ -1,5 +1,5 @@
 error: using `clone` on type `i32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:24:5
+  --> $DIR/clone_on_copy.rs:25:5
    |
 LL |     42.clone();
    |     ^^^^^^^^^^ help: try removing the `clone` call: `42`
@@ -7,43 +7,43 @@ LL |     42.clone();
    = note: `-D clippy::clone-on-copy` implied by `-D warnings`
 
 error: using `clone` on type `i32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:28:5
+  --> $DIR/clone_on_copy.rs:29:5
    |
 LL |     (&42).clone();
    |     ^^^^^^^^^^^^^ help: try dereferencing it: `*(&42)`
 
 error: using `clone` on type `i32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:31:5
+  --> $DIR/clone_on_copy.rs:32:5
    |
 LL |     rc.borrow().clone();
    |     ^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*rc.borrow()`
 
 error: using `clone` on type `u32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:34:5
+  --> $DIR/clone_on_copy.rs:35:5
    |
 LL |     x.clone().rotate_left(1);
    |     ^^^^^^^^^ help: try removing the `clone` call: `x`
 
 error: using `clone` on type `i32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:48:5
+  --> $DIR/clone_on_copy.rs:49:5
    |
 LL |     m!(42).clone();
    |     ^^^^^^^^^^^^^^ help: try removing the `clone` call: `m!(42)`
 
 error: using `clone` on type `[u32; 2]` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:58:5
+  --> $DIR/clone_on_copy.rs:59:5
    |
 LL |     x.clone()[0];
    |     ^^^^^^^^^ help: try dereferencing it: `(*x)`
 
 error: using `clone` on type `char` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:68:14
+  --> $DIR/clone_on_copy.rs:69:14
    |
 LL |     is_ascii('z'.clone());
    |              ^^^^^^^^^^^ help: try removing the `clone` call: `'z'`
 
 error: using `clone` on type `i32` which implements the `Copy` trait
-  --> $DIR/clone_on_copy.rs:72:14
+  --> $DIR/clone_on_copy.rs:73:14
    |
 LL |     vec.push(42.clone());
    |              ^^^^^^^^^^ help: try removing the `clone` call: `42`
diff --git a/src/tools/clippy/tests/ui/duration_subsec.fixed b/src/tools/clippy/tests/ui/duration_subsec.fixed
index ee5c7863eff..d92b8998e88 100644
--- a/src/tools/clippy/tests/ui/duration_subsec.fixed
+++ b/src/tools/clippy/tests/ui/duration_subsec.fixed
@@ -1,5 +1,5 @@
 // run-rustfix
-#![allow(dead_code)]
+#![allow(dead_code, clippy::needless_borrow)]
 #![warn(clippy::duration_subsec)]
 
 use std::time::Duration;
diff --git a/src/tools/clippy/tests/ui/duration_subsec.rs b/src/tools/clippy/tests/ui/duration_subsec.rs
index 3c9d2a28621..08da804996d 100644
--- a/src/tools/clippy/tests/ui/duration_subsec.rs
+++ b/src/tools/clippy/tests/ui/duration_subsec.rs
@@ -1,5 +1,5 @@
 // run-rustfix
-#![allow(dead_code)]
+#![allow(dead_code, clippy::needless_borrow)]
 #![warn(clippy::duration_subsec)]
 
 use std::time::Duration;
diff --git a/src/tools/clippy/tests/ui/enum_variants.rs b/src/tools/clippy/tests/ui/enum_variants.rs
index d3662a0a213..b2bf7c4e360 100644
--- a/src/tools/clippy/tests/ui/enum_variants.rs
+++ b/src/tools/clippy/tests/ui/enum_variants.rs
@@ -151,4 +151,11 @@ enum North {
     NoRight,
 }
 
+// #8324
+enum Phase {
+    PreLookup,
+    Lookup,
+    PostLookup,
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/eta.fixed b/src/tools/clippy/tests/ui/eta.fixed
index f938f710688..618f80cdcf8 100644
--- a/src/tools/clippy/tests/ui/eta.fixed
+++ b/src/tools/clippy/tests/ui/eta.fixed
@@ -5,13 +5,10 @@
     clippy::no_effect,
     clippy::redundant_closure_call,
     clippy::needless_pass_by_value,
-    clippy::option_map_unit_fn
-)]
-#![warn(
-    clippy::redundant_closure,
-    clippy::redundant_closure_for_method_calls,
+    clippy::option_map_unit_fn,
     clippy::needless_borrow
 )]
+#![warn(clippy::redundant_closure, clippy::redundant_closure_for_method_calls)]
 
 use std::path::{Path, PathBuf};
 
@@ -34,7 +31,7 @@ fn main() {
     Some(1).map(closure_mac!()); // don't lint closure in macro expansion
     let _: Option<Vec<u8>> = true.then(std::vec::Vec::new); // special case vec!
     let d = Some(1u8).map(|a| foo(foo2(a))); //is adjusted?
-    all(&[1, 2, 3], &2, below); //is adjusted
+    all(&[1, 2, 3], &&2, below); //is adjusted
     unsafe {
         Some(1u8).map(|a| unsafe_fn(a)); // unsafe fn
     }
diff --git a/src/tools/clippy/tests/ui/eta.rs b/src/tools/clippy/tests/ui/eta.rs
index 075bbc74922..a759e6eb514 100644
--- a/src/tools/clippy/tests/ui/eta.rs
+++ b/src/tools/clippy/tests/ui/eta.rs
@@ -5,13 +5,10 @@
     clippy::no_effect,
     clippy::redundant_closure_call,
     clippy::needless_pass_by_value,
-    clippy::option_map_unit_fn
-)]
-#![warn(
-    clippy::redundant_closure,
-    clippy::redundant_closure_for_method_calls,
+    clippy::option_map_unit_fn,
     clippy::needless_borrow
 )]
+#![warn(clippy::redundant_closure, clippy::redundant_closure_for_method_calls)]
 
 use std::path::{Path, PathBuf};
 
diff --git a/src/tools/clippy/tests/ui/eta.stderr b/src/tools/clippy/tests/ui/eta.stderr
index 8092f04c3fc..cda84982c9b 100644
--- a/src/tools/clippy/tests/ui/eta.stderr
+++ b/src/tools/clippy/tests/ui/eta.stderr
@@ -1,5 +1,5 @@
 error: redundant closure
-  --> $DIR/eta.rs:31:27
+  --> $DIR/eta.rs:28:27
    |
 LL |     let a = Some(1u8).map(|a| foo(a));
    |                           ^^^^^^^^^^ help: replace the closure with the function itself: `foo`
@@ -7,45 +7,37 @@ LL |     let a = Some(1u8).map(|a| foo(a));
    = note: `-D clippy::redundant-closure` implied by `-D warnings`
 
 error: redundant closure
-  --> $DIR/eta.rs:35:40
+  --> $DIR/eta.rs:32:40
    |
 LL |     let _: Option<Vec<u8>> = true.then(|| vec![]); // special case vec!
    |                                        ^^^^^^^^^ help: replace the closure with `Vec::new`: `std::vec::Vec::new`
 
 error: redundant closure
-  --> $DIR/eta.rs:36:35
+  --> $DIR/eta.rs:33:35
    |
 LL |     let d = Some(1u8).map(|a| foo((|b| foo2(b))(a))); //is adjusted?
    |                                   ^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo2`
 
-error: this expression borrows a reference (`&u8`) that is immediately dereferenced by the compiler
-  --> $DIR/eta.rs:37:21
-   |
-LL |     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
-   |                     ^^^ help: change this to: `&2`
-   |
-   = note: `-D clippy::needless-borrow` implied by `-D warnings`
-
 error: redundant closure
-  --> $DIR/eta.rs:37:26
+  --> $DIR/eta.rs:34:26
    |
 LL |     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
    |                          ^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `below`
 
 error: redundant closure
-  --> $DIR/eta.rs:43:27
+  --> $DIR/eta.rs:40:27
    |
 LL |     let e = Some(1u8).map(|a| divergent(a));
    |                           ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `divergent`
 
 error: redundant closure
-  --> $DIR/eta.rs:44:27
+  --> $DIR/eta.rs:41:27
    |
 LL |     let e = Some(1u8).map(|a| generic(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `generic`
 
 error: redundant closure
-  --> $DIR/eta.rs:90:51
+  --> $DIR/eta.rs:87:51
    |
 LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
    |                                                   ^^^^^^^^^^^ help: replace the closure with the method itself: `TestStruct::foo`
@@ -53,82 +45,82 @@ LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
    = note: `-D clippy::redundant-closure-for-method-calls` implied by `-D warnings`
 
 error: redundant closure
-  --> $DIR/eta.rs:91:51
+  --> $DIR/eta.rs:88:51
    |
 LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
    |                                                   ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `TestTrait::trait_foo`
 
 error: redundant closure
-  --> $DIR/eta.rs:93:42
+  --> $DIR/eta.rs:90:42
    |
 LL |     let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
    |                                          ^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::vec::Vec::clear`
 
 error: redundant closure
-  --> $DIR/eta.rs:97:29
+  --> $DIR/eta.rs:94:29
    |
 LL |     let e = Some("str").map(|s| s.to_string());
    |                             ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::string::ToString::to_string`
 
 error: redundant closure
-  --> $DIR/eta.rs:98:27
+  --> $DIR/eta.rs:95:27
    |
 LL |     let e = Some('a').map(|s| s.to_uppercase());
    |                           ^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_uppercase`
 
 error: redundant closure
-  --> $DIR/eta.rs:100:65
+  --> $DIR/eta.rs:97:65
    |
 LL |     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
    |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_ascii_uppercase`
 
 error: redundant closure
-  --> $DIR/eta.rs:163:22
+  --> $DIR/eta.rs:160:22
    |
 LL |     requires_fn_once(|| x());
    |                      ^^^^^^ help: replace the closure with the function itself: `x`
 
 error: redundant closure
-  --> $DIR/eta.rs:170:27
+  --> $DIR/eta.rs:167:27
    |
 LL |     let a = Some(1u8).map(|a| foo_ptr(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo_ptr`
 
 error: redundant closure
-  --> $DIR/eta.rs:175:27
+  --> $DIR/eta.rs:172:27
    |
 LL |     let a = Some(1u8).map(|a| closure(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `closure`
 
 error: redundant closure
-  --> $DIR/eta.rs:207:28
+  --> $DIR/eta.rs:204:28
    |
 LL |     x.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:208:28
+  --> $DIR/eta.rs:205:28
    |
 LL |     y.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:209:28
+  --> $DIR/eta.rs:206:28
    |
 LL |     z.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:216:21
+  --> $DIR/eta.rs:213:21
    |
 LL |         Some(1).map(|n| closure(n));
    |                     ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut closure`
 
 error: redundant closure
-  --> $DIR/eta.rs:235:21
+  --> $DIR/eta.rs:232:21
    |
 LL |     map_str_to_path(|s| s.as_ref());
    |                     ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::convert::AsRef::as_ref`
 
-error: aborting due to 21 previous errors
+error: aborting due to 20 previous errors
 
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
index 48e2aae75d0..3de2a51ffa5 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_variables, clippy::clone_double_ref)]
+#![allow(unused_variables, clippy::clone_double_ref, clippy::needless_borrow)]
 #![warn(clippy::explicit_deref_methods)]
 
 use std::ops::{Deref, DerefMut};
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.rs b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
index d8c8c0c5ca3..a08d7596422 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.rs
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_variables, clippy::clone_double_ref)]
+#![allow(unused_variables, clippy::clone_double_ref, clippy::needless_borrow)]
 #![warn(clippy::explicit_deref_methods)]
 
 use std::ops::{Deref, DerefMut};
diff --git a/src/tools/clippy/tests/ui/for_loop_fixable.fixed b/src/tools/clippy/tests/ui/for_loop_fixable.fixed
index f373e905d05..aa69781d15a 100644
--- a/src/tools/clippy/tests/ui/for_loop_fixable.fixed
+++ b/src/tools/clippy/tests/ui/for_loop_fixable.fixed
@@ -23,7 +23,12 @@ impl Unrelated {
     clippy::iter_next_loop,
     clippy::for_kv_map
 )]
-#[allow(clippy::linkedlist, clippy::unnecessary_mut_passed, clippy::similar_names)]
+#[allow(
+    clippy::linkedlist,
+    clippy::unnecessary_mut_passed,
+    clippy::similar_names,
+    clippy::needless_borrow
+)]
 #[allow(unused_variables)]
 fn main() {
     let mut vec = vec![1, 2, 3, 4];
diff --git a/src/tools/clippy/tests/ui/for_loop_fixable.rs b/src/tools/clippy/tests/ui/for_loop_fixable.rs
index 3814583bb6e..7c063d99511 100644
--- a/src/tools/clippy/tests/ui/for_loop_fixable.rs
+++ b/src/tools/clippy/tests/ui/for_loop_fixable.rs
@@ -23,7 +23,12 @@ impl Unrelated {
     clippy::iter_next_loop,
     clippy::for_kv_map
 )]
-#[allow(clippy::linkedlist, clippy::unnecessary_mut_passed, clippy::similar_names)]
+#[allow(
+    clippy::linkedlist,
+    clippy::unnecessary_mut_passed,
+    clippy::similar_names,
+    clippy::needless_borrow
+)]
 #[allow(unused_variables)]
 fn main() {
     let mut vec = vec![1, 2, 3, 4];
diff --git a/src/tools/clippy/tests/ui/for_loop_fixable.stderr b/src/tools/clippy/tests/ui/for_loop_fixable.stderr
index 009dbe1a0bf..ddfe66d675f 100644
--- a/src/tools/clippy/tests/ui/for_loop_fixable.stderr
+++ b/src/tools/clippy/tests/ui/for_loop_fixable.stderr
@@ -1,5 +1,5 @@
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:38:15
+  --> $DIR/for_loop_fixable.rs:43:15
    |
 LL |     for _v in vec.iter() {}
    |               ^^^^^^^^^^ help: to write this more concisely, try: `&vec`
@@ -7,13 +7,13 @@ LL |     for _v in vec.iter() {}
    = note: `-D clippy::explicit-iter-loop` implied by `-D warnings`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:40:15
+  --> $DIR/for_loop_fixable.rs:45:15
    |
 LL |     for _v in vec.iter_mut() {}
    |               ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&mut vec`
 
 error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:43:15
+  --> $DIR/for_loop_fixable.rs:48:15
    |
 LL |     for _v in out_vec.into_iter() {}
    |               ^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `out_vec`
@@ -21,73 +21,73 @@ LL |     for _v in out_vec.into_iter() {}
    = note: `-D clippy::explicit-into-iter-loop` implied by `-D warnings`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:48:15
+  --> $DIR/for_loop_fixable.rs:53:15
    |
 LL |     for _v in [1, 2, 3].iter() {}
    |               ^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[1, 2, 3]`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:52:15
+  --> $DIR/for_loop_fixable.rs:57:15
    |
 LL |     for _v in [0; 32].iter() {}
    |               ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[0; 32]`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:57:15
+  --> $DIR/for_loop_fixable.rs:62:15
    |
 LL |     for _v in ll.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&ll`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:60:15
+  --> $DIR/for_loop_fixable.rs:65:15
    |
 LL |     for _v in vd.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&vd`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:63:15
+  --> $DIR/for_loop_fixable.rs:68:15
    |
 LL |     for _v in bh.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&bh`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:66:15
+  --> $DIR/for_loop_fixable.rs:71:15
    |
 LL |     for _v in hm.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&hm`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:69:15
+  --> $DIR/for_loop_fixable.rs:74:15
    |
 LL |     for _v in bt.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&bt`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:72:15
+  --> $DIR/for_loop_fixable.rs:77:15
    |
 LL |     for _v in hs.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&hs`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:75:15
+  --> $DIR/for_loop_fixable.rs:80:15
    |
 LL |     for _v in bs.iter() {}
    |               ^^^^^^^^^ help: to write this more concisely, try: `&bs`
 
 error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:250:18
+  --> $DIR/for_loop_fixable.rs:255:18
    |
 LL |         for i in iterator.into_iter() {
    |                  ^^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `iterator`
 
 error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:270:18
+  --> $DIR/for_loop_fixable.rs:275:18
    |
 LL |         for _ in t.into_iter() {}
    |                  ^^^^^^^^^^^^^ help: to write this more concisely, try: `&t`
 
 error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:272:18
+  --> $DIR/for_loop_fixable.rs:277:18
    |
 LL |         for _ in r.into_iter() {}
    |                  ^^^^^^^^^^^^^ help: to write this more concisely, try: `r`
diff --git a/src/tools/clippy/tests/ui/format.fixed b/src/tools/clippy/tests/ui/format.fixed
index 78d2bfd474e..d08f8f52495 100644
--- a/src/tools/clippy/tests/ui/format.fixed
+++ b/src/tools/clippy/tests/ui/format.fixed
@@ -1,6 +1,11 @@
 // run-rustfix
 
-#![allow(clippy::print_literal, clippy::redundant_clone, clippy::to_string_in_format_args)]
+#![allow(
+    clippy::print_literal,
+    clippy::redundant_clone,
+    clippy::to_string_in_format_args,
+    clippy::needless_borrow
+)]
 #![warn(clippy::useless_format)]
 
 struct Foo(pub String);
diff --git a/src/tools/clippy/tests/ui/format.rs b/src/tools/clippy/tests/ui/format.rs
index 009c1aa216f..4a10b580d26 100644
--- a/src/tools/clippy/tests/ui/format.rs
+++ b/src/tools/clippy/tests/ui/format.rs
@@ -1,6 +1,11 @@
 // run-rustfix
 
-#![allow(clippy::print_literal, clippy::redundant_clone, clippy::to_string_in_format_args)]
+#![allow(
+    clippy::print_literal,
+    clippy::redundant_clone,
+    clippy::to_string_in_format_args,
+    clippy::needless_borrow
+)]
 #![warn(clippy::useless_format)]
 
 struct Foo(pub String);
diff --git a/src/tools/clippy/tests/ui/format.stderr b/src/tools/clippy/tests/ui/format.stderr
index 660be57585e..f25c7fb1ff1 100644
--- a/src/tools/clippy/tests/ui/format.stderr
+++ b/src/tools/clippy/tests/ui/format.stderr
@@ -1,5 +1,5 @@
 error: useless use of `format!`
-  --> $DIR/format.rs:13:5
+  --> $DIR/format.rs:18:5
    |
 LL |     format!("foo");
    |     ^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"foo".to_string()`
@@ -7,19 +7,19 @@ LL |     format!("foo");
    = note: `-D clippy::useless-format` implied by `-D warnings`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:14:5
+  --> $DIR/format.rs:19:5
    |
 LL |     format!("{{}}");
    |     ^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"{}".to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:15:5
+  --> $DIR/format.rs:20:5
    |
 LL |     format!("{{}} abc {{}}");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"{} abc {}".to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:16:5
+  --> $DIR/format.rs:21:5
    |
 LL | /     format!(
 LL | |         r##"foo {{}}
@@ -34,79 +34,79 @@ LL ~ " bar"##.to_string();
    |
 
 error: useless use of `format!`
-  --> $DIR/format.rs:21:13
+  --> $DIR/format.rs:26:13
    |
 LL |     let _ = format!("");
    |             ^^^^^^^^^^^ help: consider using `String::new()`: `String::new()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:23:5
+  --> $DIR/format.rs:28:5
    |
 LL |     format!("{}", "foo");
    |     ^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"foo".to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:27:5
+  --> $DIR/format.rs:32:5
    |
 LL |     format!("{:+}", "foo"); // Warn when the format makes no difference.
    |     ^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"foo".to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:28:5
+  --> $DIR/format.rs:33:5
    |
 LL |     format!("{:<}", "foo"); // Warn when the format makes no difference.
    |     ^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"foo".to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:33:5
+  --> $DIR/format.rs:38:5
    |
 LL |     format!("{}", arg);
    |     ^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `arg.to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:37:5
+  --> $DIR/format.rs:42:5
    |
 LL |     format!("{:+}", arg); // Warn when the format makes no difference.
    |     ^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `arg.to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:38:5
+  --> $DIR/format.rs:43:5
    |
 LL |     format!("{:<}", arg); // Warn when the format makes no difference.
    |     ^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `arg.to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:65:5
+  --> $DIR/format.rs:70:5
    |
 LL |     format!("{}", 42.to_string());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `42.to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:67:5
+  --> $DIR/format.rs:72:5
    |
 LL |     format!("{}", x.display().to_string());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `x.display().to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:71:18
+  --> $DIR/format.rs:76:18
    |
 LL |     let _ = Some(format!("{}", a + "bar"));
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `a + "bar"`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:75:22
+  --> $DIR/format.rs:80:22
    |
 LL |     let _s: String = format!("{}", &*v.join("/n"));
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `(&*v.join("/n")).to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:81:13
+  --> $DIR/format.rs:86:13
    |
 LL |     let _ = format!("{x}");
    |             ^^^^^^^^^^^^^^ help: consider using `.to_string()`: `x.to_string()`
 
 error: useless use of `format!`
-  --> $DIR/format.rs:83:13
+  --> $DIR/format.rs:88:13
    |
 LL |     let _ = format!("{y}", y = x);
    |             ^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `x.to_string()`
diff --git a/src/tools/clippy/tests/ui/needless_borrow.fixed b/src/tools/clippy/tests/ui/needless_borrow.fixed
index 9e37fb92559..b856f1375d3 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.fixed
+++ b/src/tools/clippy/tests/ui/needless_borrow.fixed
@@ -45,6 +45,33 @@ fn main() {
         let b = &mut b;
         x(b);
     }
+
+    // Issue #8191
+    let mut x = 5;
+    let mut x = &mut x;
+
+    mut_ref(x);
+    mut_ref(x);
+    let y: &mut i32 = x;
+    let y: &mut i32 = x;
+
+    let y = match 0 {
+        // Don't lint. Removing the borrow would move 'x'
+        0 => &mut x,
+        _ => &mut *x,
+    };
+
+    *x = 5;
+
+    let s = String::new();
+    let _ = s.len();
+    let _ = s.capacity();
+    let _ = s.capacity();
+
+    let x = (1, 2);
+    let _ = x.0;
+    let x = &x as *const (i32, i32);
+    let _ = unsafe { (*x).0 };
 }
 
 #[allow(clippy::needless_borrowed_reference)]
diff --git a/src/tools/clippy/tests/ui/needless_borrow.rs b/src/tools/clippy/tests/ui/needless_borrow.rs
index 093277784be..0bfe222a3dc 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.rs
+++ b/src/tools/clippy/tests/ui/needless_borrow.rs
@@ -45,6 +45,33 @@ fn main() {
         let b = &mut b;
         x(&b);
     }
+
+    // Issue #8191
+    let mut x = 5;
+    let mut x = &mut x;
+
+    mut_ref(&mut x);
+    mut_ref(&mut &mut x);
+    let y: &mut i32 = &mut x;
+    let y: &mut i32 = &mut &mut x;
+
+    let y = match 0 {
+        // Don't lint. Removing the borrow would move 'x'
+        0 => &mut x,
+        _ => &mut *x,
+    };
+
+    *x = 5;
+
+    let s = String::new();
+    let _ = (&s).len();
+    let _ = (&s).capacity();
+    let _ = (&&s).capacity();
+
+    let x = (1, 2);
+    let _ = (&x).0;
+    let x = &x as *const (i32, i32);
+    let _ = unsafe { (&*x).0 };
 }
 
 #[allow(clippy::needless_borrowed_reference)]
diff --git a/src/tools/clippy/tests/ui/needless_borrow.stderr b/src/tools/clippy/tests/ui/needless_borrow.stderr
index 03a5b3d260e..b90e8448db0 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.stderr
+++ b/src/tools/clippy/tests/ui/needless_borrow.stderr
@@ -1,4 +1,4 @@
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:9:15
    |
 LL |     let _ = x(&&a); // warn
@@ -6,59 +6,113 @@ LL |     let _ = x(&&a); // warn
    |
    = note: `-D clippy::needless-borrow` implied by `-D warnings`
 
-error: this expression borrows a reference (`&mut i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:13:13
    |
 LL |     mut_ref(&mut &mut b); // warn
    |             ^^^^^^^^^^^ help: change this to: `&mut b`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:25:13
    |
 LL |             &&a
    |             ^^^ help: change this to: `&a`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:27:15
    |
 LL |         46 => &&a,
    |               ^^^ help: change this to: `&a`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:33:27
    |
 LL |                     break &ref_a;
    |                           ^^^^^^ help: change this to: `ref_a`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:40:15
    |
 LL |     let _ = x(&&&a);
    |               ^^^^ help: change this to: `&a`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:41:15
    |
 LL |     let _ = x(&mut &&a);
    |               ^^^^^^^^ help: change this to: `&a`
 
-error: this expression borrows a reference (`&mut i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:42:15
    |
 LL |     let _ = x(&&&mut b);
    |               ^^^^^^^^ help: change this to: `&mut b`
 
-error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:43:15
    |
 LL |     let _ = x(&&ref_a);
    |               ^^^^^^^ help: change this to: `ref_a`
 
-error: this expression borrows a reference (`&mut i32`) that is immediately dereferenced by the compiler
+error: this expression creates a reference which is immediately dereferenced by the compiler
   --> $DIR/needless_borrow.rs:46:11
    |
 LL |         x(&b);
    |           ^^ help: change this to: `b`
 
-error: aborting due to 10 previous errors
+error: this expression creates a reference which is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:53:13
+   |
+LL |     mut_ref(&mut x);
+   |             ^^^^^^ help: change this to: `x`
+
+error: this expression creates a reference which is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:54:13
+   |
+LL |     mut_ref(&mut &mut x);
+   |             ^^^^^^^^^^^ help: change this to: `x`
+
+error: this expression creates a reference which is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:55:23
+   |
+LL |     let y: &mut i32 = &mut x;
+   |                       ^^^^^^ help: change this to: `x`
+
+error: this expression creates a reference which is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:56:23
+   |
+LL |     let y: &mut i32 = &mut &mut x;
+   |                       ^^^^^^^^^^^ help: change this to: `x`
+
+error: this expression borrows a value the compiler would automatically borrow
+  --> $DIR/needless_borrow.rs:67:13
+   |
+LL |     let _ = (&s).len();
+   |             ^^^^ help: change this to: `s`
+
+error: this expression borrows a value the compiler would automatically borrow
+  --> $DIR/needless_borrow.rs:68:13
+   |
+LL |     let _ = (&s).capacity();
+   |             ^^^^ help: change this to: `s`
+
+error: this expression creates a reference which is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:69:13
+   |
+LL |     let _ = (&&s).capacity();
+   |             ^^^^^ help: change this to: `s`
+
+error: this expression borrows a value the compiler would automatically borrow
+  --> $DIR/needless_borrow.rs:72:13
+   |
+LL |     let _ = (&x).0;
+   |             ^^^^ help: change this to: `x`
+
+error: this expression borrows a value the compiler would automatically borrow
+  --> $DIR/needless_borrow.rs:74:22
+   |
+LL |     let _ = unsafe { (&*x).0 };
+   |                      ^^^^^ help: change this to: `(*x)`
+
+error: aborting due to 19 previous errors
 
diff --git a/src/tools/clippy/tests/ui/needless_lifetimes.rs b/src/tools/clippy/tests/ui/needless_lifetimes.rs
index b07c4a23810..f3eafe8e927 100644
--- a/src/tools/clippy/tests/ui/needless_lifetimes.rs
+++ b/src/tools/clippy/tests/ui/needless_lifetimes.rs
@@ -1,5 +1,11 @@
 #![warn(clippy::needless_lifetimes)]
-#![allow(dead_code, clippy::needless_pass_by_value, clippy::unnecessary_wraps, dyn_drop)]
+#![allow(
+    dead_code,
+    clippy::boxed_local,
+    clippy::needless_pass_by_value,
+    clippy::unnecessary_wraps,
+    dyn_drop
+)]
 
 fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
 
@@ -369,4 +375,47 @@ mod issue6159 {
     }
 }
 
+mod issue7296 {
+    use std::rc::Rc;
+    use std::sync::Arc;
+
+    struct Foo;
+    impl Foo {
+        fn implicit<'a>(&'a self) -> &'a () {
+            &()
+        }
+        fn implicit_mut<'a>(&'a mut self) -> &'a () {
+            &()
+        }
+
+        fn explicit<'a>(self: &'a Arc<Self>) -> &'a () {
+            &()
+        }
+        fn explicit_mut<'a>(self: &'a mut Rc<Self>) -> &'a () {
+            &()
+        }
+
+        fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
+            &()
+        }
+    }
+
+    trait Bar {
+        fn implicit<'a>(&'a self) -> &'a ();
+        fn implicit_provided<'a>(&'a self) -> &'a () {
+            &()
+        }
+
+        fn explicit<'a>(self: &'a Arc<Self>) -> &'a ();
+        fn explicit_provided<'a>(self: &'a Arc<Self>) -> &'a () {
+            &()
+        }
+
+        fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a ();
+        fn lifetime_elsewhere_provided<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
+            &()
+        }
+    }
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/needless_lifetimes.stderr b/src/tools/clippy/tests/ui/needless_lifetimes.stderr
index 4114e6f1832..ffa152427a9 100644
--- a/src/tools/clippy/tests/ui/needless_lifetimes.stderr
+++ b/src/tools/clippy/tests/ui/needless_lifetimes.stderr
@@ -1,5 +1,5 @@
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:4:1
+  --> $DIR/needless_lifetimes.rs:10:1
    |
 LL | fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -7,148 +7,190 @@ LL | fn distinct_lifetimes<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: u8) {}
    = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:6:1
+  --> $DIR/needless_lifetimes.rs:12:1
    |
 LL | fn distinct_and_static<'a, 'b>(_x: &'a u8, _y: &'b u8, _z: &'static u8) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:16:1
+  --> $DIR/needless_lifetimes.rs:22:1
    |
 LL | fn in_and_out<'a>(x: &'a u8, _y: u8) -> &'a u8 {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:50:1
+  --> $DIR/needless_lifetimes.rs:56:1
    |
 LL | fn deep_reference_3<'a>(x: &'a u8, _y: u8) -> Result<&'a u8, ()> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:55:1
+  --> $DIR/needless_lifetimes.rs:61:1
    |
 LL | fn where_clause_without_lt<'a, T>(x: &'a u8, _y: u8) -> Result<&'a u8, ()>
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:67:1
+  --> $DIR/needless_lifetimes.rs:73:1
    |
 LL | fn lifetime_param_2<'a, 'b>(_x: Ref<'a>, _y: &'b u8) {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:91:1
+  --> $DIR/needless_lifetimes.rs:97:1
    |
 LL | fn fn_bound_2<'a, F, I>(_m: Lt<'a, I>, _f: F) -> Lt<'a, I>
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:121:5
+  --> $DIR/needless_lifetimes.rs:127:5
    |
 LL |     fn self_and_out<'s>(&'s self) -> &'s u8 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:130:5
+  --> $DIR/needless_lifetimes.rs:136:5
    |
 LL |     fn distinct_self_and_in<'s, 't>(&'s self, _x: &'t u8) {}
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:149:1
+  --> $DIR/needless_lifetimes.rs:155:1
    |
 LL | fn struct_with_lt<'a>(_foo: Foo<'a>) -> &'a str {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:179:1
+  --> $DIR/needless_lifetimes.rs:185:1
    |
 LL | fn trait_obj_elided2<'a>(_arg: &'a dyn Drop) -> &'a str {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:185:1
+  --> $DIR/needless_lifetimes.rs:191:1
    |
 LL | fn alias_with_lt<'a>(_foo: FooAlias<'a>) -> &'a str {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:204:1
+  --> $DIR/needless_lifetimes.rs:210:1
    |
 LL | fn named_input_elided_output<'a>(_arg: &'a str) -> &str {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:212:1
+  --> $DIR/needless_lifetimes.rs:218:1
    |
 LL | fn trait_bound_ok<'a, T: WithLifetime<'static>>(_: &'a u8, _: T) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:248:1
+  --> $DIR/needless_lifetimes.rs:254:1
    |
 LL | fn out_return_type_lts<'a>(e: &'a str) -> Cow<'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:255:9
+  --> $DIR/needless_lifetimes.rs:261:9
    |
 LL |         fn needless_lt<'a>(x: &'a u8) {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:259:9
+  --> $DIR/needless_lifetimes.rs:265:9
    |
 LL |         fn needless_lt<'a>(_x: &'a u8) {}
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:272:9
+  --> $DIR/needless_lifetimes.rs:278:9
    |
 LL |         fn baz<'a>(&'a self) -> impl Foo + 'a {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:301:5
+  --> $DIR/needless_lifetimes.rs:307:5
    |
 LL |     fn impl_trait_elidable_nested_named_lifetimes<'a>(i: &'a i32, f: impl for<'b> Fn(&'b i32) -> &'b i32) -> &'a i32 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:304:5
+  --> $DIR/needless_lifetimes.rs:310:5
    |
 LL |     fn impl_trait_elidable_nested_anonymous_lifetimes<'a>(i: &'a i32, f: impl Fn(&i32) -> &i32) -> &'a i32 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:313:5
+  --> $DIR/needless_lifetimes.rs:319:5
    |
 LL |     fn generics_elidable<'a, T: Fn(&i32) -> &i32>(i: &'a i32, f: T) -> &'a i32 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:325:5
+  --> $DIR/needless_lifetimes.rs:331:5
    |
 LL |     fn where_clause_elidadable<'a, T>(i: &'a i32, f: T) -> &'a i32
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:340:5
+  --> $DIR/needless_lifetimes.rs:346:5
    |
 LL |     fn pointer_fn_elidable<'a>(i: &'a i32, f: fn(&i32) -> &i32) -> &'a i32 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:353:5
+  --> $DIR/needless_lifetimes.rs:359:5
    |
 LL |     fn nested_fn_pointer_3<'a>(_: &'a i32) -> fn(fn(&i32) -> &i32) -> i32 {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
-  --> $DIR/needless_lifetimes.rs:356:5
+  --> $DIR/needless_lifetimes.rs:362:5
    |
 LL |     fn nested_fn_pointer_4<'a>(_: &'a i32) -> impl Fn(fn(&i32)) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 25 previous errors
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:384:9
+   |
+LL |         fn implicit<'a>(&'a self) -> &'a () {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:387:9
+   |
+LL |         fn implicit_mut<'a>(&'a mut self) -> &'a () {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:398:9
+   |
+LL |         fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:404:9
+   |
+LL |         fn implicit<'a>(&'a self) -> &'a ();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:405:9
+   |
+LL |         fn implicit_provided<'a>(&'a self) -> &'a () {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:414:9
+   |
+LL |         fn lifetime_elsewhere<'a>(self: Box<Self>, here: &'a ()) -> &'a ();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: explicit lifetimes given in parameter types where they could be elided (or replaced with `'_` if needed by type declaration)
+  --> $DIR/needless_lifetimes.rs:415:9
+   |
+LL |         fn lifetime_elsewhere_provided<'a>(self: Box<Self>, here: &'a ()) -> &'a () {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 32 previous errors
 
diff --git a/src/tools/clippy/tests/ui/needless_question_mark.fixed b/src/tools/clippy/tests/ui/needless_question_mark.fixed
index f1fc81aa12b..ba9d15e59d0 100644
--- a/src/tools/clippy/tests/ui/needless_question_mark.fixed
+++ b/src/tools/clippy/tests/ui/needless_question_mark.fixed
@@ -125,3 +125,16 @@ pub fn test2() {
     let x = Some(3);
     let _x = some_and_qmark_in_macro!(x?);
 }
+
+async fn async_option_bad(to: TO) -> Option<usize> {
+    let _ = Some(3);
+    to.magic
+}
+
+async fn async_deref_ref(s: Option<&String>) -> Option<&str> {
+    Some(s?)
+}
+
+async fn async_result_bad(s: TR) -> Result<usize, bool> {
+    s.magic
+}
diff --git a/src/tools/clippy/tests/ui/needless_question_mark.rs b/src/tools/clippy/tests/ui/needless_question_mark.rs
index 44a0c5f61b5..3a6523e8fe8 100644
--- a/src/tools/clippy/tests/ui/needless_question_mark.rs
+++ b/src/tools/clippy/tests/ui/needless_question_mark.rs
@@ -125,3 +125,16 @@ pub fn test2() {
     let x = Some(3);
     let _x = some_and_qmark_in_macro!(x?);
 }
+
+async fn async_option_bad(to: TO) -> Option<usize> {
+    let _ = Some(3);
+    Some(to.magic?)
+}
+
+async fn async_deref_ref(s: Option<&String>) -> Option<&str> {
+    Some(s?)
+}
+
+async fn async_result_bad(s: TR) -> Result<usize, bool> {
+    Ok(s.magic?)
+}
diff --git a/src/tools/clippy/tests/ui/needless_question_mark.stderr b/src/tools/clippy/tests/ui/needless_question_mark.stderr
index 57c3d48c761..f8308e24e77 100644
--- a/src/tools/clippy/tests/ui/needless_question_mark.stderr
+++ b/src/tools/clippy/tests/ui/needless_question_mark.stderr
@@ -77,5 +77,17 @@ LL |     let _x = some_and_qmark_in_macro!(x?);
    |
    = note: this error originates in the macro `some_and_qmark_in_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 12 previous errors
+error: question mark operator is useless here
+  --> $DIR/needless_question_mark.rs:131:5
+   |
+LL |     Some(to.magic?)
+   |     ^^^^^^^^^^^^^^^ help: try removing question mark and `Some()`: `to.magic`
+
+error: question mark operator is useless here
+  --> $DIR/needless_question_mark.rs:139:5
+   |
+LL |     Ok(s.magic?)
+   |     ^^^^^^^^^^^^ help: try removing question mark and `Ok()`: `s.magic`
+
+error: aborting due to 14 previous errors
 
diff --git a/src/tools/clippy/tests/ui/op_ref.rs b/src/tools/clippy/tests/ui/op_ref.rs
index ab9c4d34c88..d8bf66603d9 100644
--- a/src/tools/clippy/tests/ui/op_ref.rs
+++ b/src/tools/clippy/tests/ui/op_ref.rs
@@ -1,7 +1,7 @@
 #![allow(unused_variables, clippy::blacklisted_name)]
 #![warn(clippy::op_ref)]
 use std::collections::HashSet;
-use std::ops::BitAnd;
+use std::ops::{BitAnd, Mul};
 
 fn main() {
     let tracked_fds: HashSet<i32> = HashSet::new();
@@ -55,3 +55,40 @@ fn main() {
     let y = Y(2);
     let z = x & &y;
 }
+
+#[derive(Clone, Copy)]
+struct A(i32);
+#[derive(Clone, Copy)]
+struct B(i32);
+
+impl Mul<&A> for B {
+    type Output = i32;
+    fn mul(self, rhs: &A) -> Self::Output {
+        self.0 * rhs.0
+    }
+}
+impl Mul<A> for B {
+    type Output = i32;
+    fn mul(self, rhs: A) -> Self::Output {
+        // Should not lint because removing the reference would lead to unconditional recursion
+        self * &rhs
+    }
+}
+impl Mul<&A> for A {
+    type Output = i32;
+    fn mul(self, rhs: &A) -> Self::Output {
+        self.0 * rhs.0
+    }
+}
+impl Mul<A> for A {
+    type Output = i32;
+    fn mul(self, rhs: A) -> Self::Output {
+        let one = B(1);
+        let two = 2;
+        let three = 3;
+        let _ = one * &self;
+        let _ = two + &three;
+        // Removing the reference would lead to unconditional recursion
+        self * &rhs
+    }
+}
diff --git a/src/tools/clippy/tests/ui/op_ref.stderr b/src/tools/clippy/tests/ui/op_ref.stderr
index 992417084bd..fe36c01166f 100644
--- a/src/tools/clippy/tests/ui/op_ref.stderr
+++ b/src/tools/clippy/tests/ui/op_ref.stderr
@@ -18,5 +18,21 @@ LL |     let z = x & &y;
    |                 |
    |                 help: use the right value directly: `y`
 
-error: aborting due to 2 previous errors
+error: taken reference of right operand
+  --> $DIR/op_ref.rs:89:17
+   |
+LL |         let _ = one * &self;
+   |                 ^^^^^^-----
+   |                       |
+   |                       help: use the right value directly: `self`
+
+error: taken reference of right operand
+  --> $DIR/op_ref.rs:90:17
+   |
+LL |         let _ = two + &three;
+   |                 ^^^^^^------
+   |                       |
+   |                       help: use the right value directly: `three`
+
+error: aborting due to 4 previous errors
 
diff --git a/src/tools/clippy/tests/ui/ptr_arg.rs b/src/tools/clippy/tests/ui/ptr_arg.rs
index 67bfef06a05..ed724237808 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.rs
+++ b/src/tools/clippy/tests/ui/ptr_arg.rs
@@ -9,7 +9,6 @@ fn do_vec(x: &Vec<i64>) {
 }
 
 fn do_vec_mut(x: &mut Vec<i64>) {
-    // no error here
     //Nothing here
 }
 
@@ -18,7 +17,6 @@ fn do_str(x: &String) {
 }
 
 fn do_str_mut(x: &mut String) {
-    // no error here
     //Nothing here either
 }
 
@@ -27,7 +25,6 @@ fn do_path(x: &PathBuf) {
 }
 
 fn do_path_mut(x: &mut PathBuf) {
-    // no error here
     //Nothing here either
 }
 
@@ -52,7 +49,7 @@ fn cloned(x: &Vec<u8>) -> Vec<u8> {
     let e = x.clone();
     let f = e.clone(); // OK
     let g = x;
-    let h = g.clone(); // Alas, we cannot reliably detect this without following data.
+    let h = g.clone();
     let i = (e).clone();
     x.clone()
 }
@@ -156,6 +153,30 @@ mod issue6509 {
     }
 }
 
+fn mut_vec_slice_methods(v: &mut Vec<u32>) {
+    v.copy_within(1..5, 10);
+}
+
+fn mut_vec_vec_methods(v: &mut Vec<u32>) {
+    v.clear();
+}
+
+fn vec_contains(v: &Vec<u32>) -> bool {
+    [vec![], vec![0]].as_slice().contains(v)
+}
+
+fn fn_requires_vec(v: &Vec<u32>) -> bool {
+    vec_contains(v)
+}
+
+fn impl_fn_requires_vec(v: &Vec<u32>, f: impl Fn(&Vec<u32>)) {
+    f(v);
+}
+
+fn dyn_fn_requires_vec(v: &Vec<u32>, f: &dyn Fn(&Vec<u32>)) {
+    f(v);
+}
+
 // No error for types behind an alias (#7699)
 type A = Vec<u8>;
 fn aliased(a: &A) {}
diff --git a/src/tools/clippy/tests/ui/ptr_arg.stderr b/src/tools/clippy/tests/ui/ptr_arg.stderr
index 64594eb870c..a9613daadde 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.stderr
+++ b/src/tools/clippy/tests/ui/ptr_arg.stderr
@@ -1,4 +1,4 @@
-error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
+error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
   --> $DIR/ptr_arg.rs:7:14
    |
 LL | fn do_vec(x: &Vec<i64>) {
@@ -6,170 +6,154 @@ LL | fn do_vec(x: &Vec<i64>) {
    |
    = note: `-D clippy::ptr-arg` implied by `-D warnings`
 
+error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:11:18
+   |
+LL | fn do_vec_mut(x: &mut Vec<i64>) {
+   |                  ^^^^^^^^^^^^^ help: change this to: `&mut [i64]`
+
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:16:14
+  --> $DIR/ptr_arg.rs:15:14
    |
 LL | fn do_str(x: &String) {
    |              ^^^^^^^ help: change this to: `&str`
 
+error: writing `&mut String` instead of `&mut str` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:19:18
+   |
+LL | fn do_str_mut(x: &mut String) {
+   |                  ^^^^^^^^^^^ help: change this to: `&mut str`
+
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:25:15
+  --> $DIR/ptr_arg.rs:23:15
    |
 LL | fn do_path(x: &PathBuf) {
    |               ^^^^^^^^ help: change this to: `&Path`
 
-error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:38:18
+error: writing `&mut PathBuf` instead of `&mut Path` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:27:19
+   |
+LL | fn do_path_mut(x: &mut PathBuf) {
+   |                   ^^^^^^^^^^^^ help: change this to: `&mut Path`
+
+error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:35:18
    |
 LL |     fn do_vec(x: &Vec<i64>);
    |                  ^^^^^^^^^ help: change this to: `&[i64]`
 
-error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:51:14
+error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:48:14
    |
 LL | fn cloned(x: &Vec<u8>) -> Vec<u8> {
    |              ^^^^^^^^
    |
 help: change this to
    |
-LL | fn cloned(x: &[u8]) -> Vec<u8> {
-   |              ~~~~~
-help: change `x.clone()` to
-   |
-LL |     let e = x.to_owned();
-   |             ~~~~~~~~~~~~
-help: change `x.clone()` to
-   |
-LL |     x.to_owned()
-   |
+LL ~ fn cloned(x: &[u8]) -> Vec<u8> {
+LL ~     let e = x.to_owned();
+LL |     let f = e.clone(); // OK
+LL |     let g = x;
+LL ~     let h = g.to_owned();
+LL |     let i = (e).clone();
+ ...
 
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:60:18
+  --> $DIR/ptr_arg.rs:57:18
    |
 LL | fn str_cloned(x: &String) -> String {
    |                  ^^^^^^^
    |
 help: change this to
    |
-LL | fn str_cloned(x: &str) -> String {
-   |                  ~~~~
-help: change `x.clone()` to
-   |
-LL |     let a = x.to_string();
-   |             ~~~~~~~~~~~~~
-help: change `x.clone()` to
-   |
-LL |     let b = x.to_string();
-   |             ~~~~~~~~~~~~~
-help: change `x.clone()` to
-   |
-LL |     x.to_string()
+LL ~ fn str_cloned(x: &str) -> String {
+LL ~     let a = x.to_owned();
+LL ~     let b = x.to_owned();
+LL |     let c = b.clone();
+LL |     let d = a.clone().clone().clone();
+LL ~     x.to_owned()
    |
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:68:19
+  --> $DIR/ptr_arg.rs:65:19
    |
 LL | fn path_cloned(x: &PathBuf) -> PathBuf {
    |                   ^^^^^^^^
    |
 help: change this to
    |
-LL | fn path_cloned(x: &Path) -> PathBuf {
-   |                   ~~~~~
-help: change `x.clone()` to
-   |
-LL |     let a = x.to_path_buf();
-   |             ~~~~~~~~~~~~~~~
-help: change `x.clone()` to
-   |
-LL |     let b = x.to_path_buf();
-   |             ~~~~~~~~~~~~~~~
-help: change `x.clone()` to
-   |
-LL |     x.to_path_buf()
+LL ~ fn path_cloned(x: &Path) -> PathBuf {
+LL ~     let a = x.to_path_buf();
+LL ~     let b = x.to_path_buf();
+LL |     let c = b.clone();
+LL |     let d = a.clone().clone().clone();
+LL ~     x.to_path_buf()
    |
 
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:76:44
+  --> $DIR/ptr_arg.rs:73:44
    |
 LL | fn false_positive_capacity(x: &Vec<u8>, y: &String) {
    |                                            ^^^^^^^
    |
 help: change this to
    |
-LL | fn false_positive_capacity(x: &Vec<u8>, y: &str) {
-   |                                            ~~~~
-help: change `y.clone()` to
+LL ~ fn false_positive_capacity(x: &Vec<u8>, y: &str) {
+LL |     let a = x.capacity();
+LL ~     let b = y.to_owned();
+LL ~     let c = y;
    |
-LL |     let b = y.to_string();
-   |             ~~~~~~~~~~~~~
-help: change `y.as_str()` to
-   |
-LL |     let c = y;
-   |             ~
 
 error: using a reference to `Cow` is not recommended
-  --> $DIR/ptr_arg.rs:90:25
+  --> $DIR/ptr_arg.rs:87:25
    |
 LL | fn test_cow_with_ref(c: &Cow<[i32]>) {}
    |                         ^^^^^^^^^^^ help: change this to: `&[i32]`
 
-error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:143:21
+error: writing `&Vec` instead of `&[_]` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:140:21
    |
 LL |     fn foo_vec(vec: &Vec<u8>) {
    |                     ^^^^^^^^
    |
 help: change this to
    |
-LL |     fn foo_vec(vec: &[u8]) {
-   |                     ~~~~~
-help: change `vec.clone()` to
-   |
-LL |         let _ = vec.to_owned().pop();
-   |                 ~~~~~~~~~~~~~~
-help: change `vec.clone()` to
+LL ~     fn foo_vec(vec: &[u8]) {
+LL ~         let _ = vec.to_owned().pop();
+LL ~         let _ = vec.to_owned().clone();
    |
-LL |         let _ = vec.to_owned().clone();
-   |                 ~~~~~~~~~~~~~~
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:148:23
+  --> $DIR/ptr_arg.rs:145:23
    |
 LL |     fn foo_path(path: &PathBuf) {
    |                       ^^^^^^^^
    |
 help: change this to
    |
-LL |     fn foo_path(path: &Path) {
-   |                       ~~~~~
-help: change `path.clone()` to
+LL ~     fn foo_path(path: &Path) {
+LL ~         let _ = path.to_path_buf().pop();
+LL ~         let _ = path.to_path_buf().clone();
    |
-LL |         let _ = path.to_path_buf().pop();
-   |                 ~~~~~~~~~~~~~~~~~~
-help: change `path.clone()` to
-   |
-LL |         let _ = path.to_path_buf().clone();
-   |                 ~~~~~~~~~~~~~~~~~~
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:153:21
+  --> $DIR/ptr_arg.rs:150:21
    |
 LL |     fn foo_str(str: &PathBuf) {
    |                     ^^^^^^^^
    |
 help: change this to
    |
-LL |     fn foo_str(str: &Path) {
-   |                     ~~~~~
-help: change `str.clone()` to
+LL ~     fn foo_str(str: &Path) {
+LL ~         let _ = str.to_path_buf().pop();
+LL ~         let _ = str.to_path_buf().clone();
    |
-LL |         let _ = str.to_path_buf().pop();
-   |                 ~~~~~~~~~~~~~~~~~
-help: change `str.clone()` to
+
+error: writing `&mut Vec` instead of `&mut [_]` involves a new object where a slice will do
+  --> $DIR/ptr_arg.rs:156:29
    |
-LL |         let _ = str.to_path_buf().clone();
-   |                 ~~~~~~~~~~~~~~~~~
+LL | fn mut_vec_slice_methods(v: &mut Vec<u32>) {
+   |                             ^^^^^^^^^^^^^ help: change this to: `&mut [u32]`
 
-error: aborting due to 12 previous errors
+error: aborting due to 16 previous errors
 
diff --git a/src/tools/clippy/tests/ui/redundant_pattern_matching_option.fixed b/src/tools/clippy/tests/ui/redundant_pattern_matching_option.fixed
index cc93859269c..a89845c1dd3 100644
--- a/src/tools/clippy/tests/ui/redundant_pattern_matching_option.fixed
+++ b/src/tools/clippy/tests/ui/redundant_pattern_matching_option.fixed
@@ -81,7 +81,7 @@ const fn issue6067() {
     None::<()>.is_none();
 }
 
-#[allow(clippy::deref_addrof, dead_code)]
+#[allow(clippy::deref_addrof, dead_code, clippy::needless_borrow)]
 fn issue7921() {
     if (&None::<()>).is_none() {}
     if (&None::<()>).is_none() {}
diff --git a/src/tools/clippy/tests/ui/redundant_pattern_matching_option.rs b/src/tools/clippy/tests/ui/redundant_pattern_matching_option.rs
index 280dca40c01..d6f44403487 100644
--- a/src/tools/clippy/tests/ui/redundant_pattern_matching_option.rs
+++ b/src/tools/clippy/tests/ui/redundant_pattern_matching_option.rs
@@ -96,7 +96,7 @@ const fn issue6067() {
     };
 }
 
-#[allow(clippy::deref_addrof, dead_code)]
+#[allow(clippy::deref_addrof, dead_code, clippy::needless_borrow)]
 fn issue7921() {
     if let None = *(&None::<()>) {}
     if let None = *&None::<()> {}
diff --git a/src/tools/clippy/tests/ui/rename.fixed b/src/tools/clippy/tests/ui/rename.fixed
index b9425733a8b..8bddec576ed 100644
--- a/src/tools/clippy/tests/ui/rename.fixed
+++ b/src/tools/clippy/tests/ui/rename.fixed
@@ -54,6 +54,7 @@
 #![warn(clippy::match_result_ok)]
 #![warn(clippy::disallowed_types)]
 #![warn(clippy::disallowed_methods)]
+#![warn(clippy::needless_borrow)]
 // uplifted lints
 #![warn(invalid_value)]
 #![warn(array_into_iter)]
diff --git a/src/tools/clippy/tests/ui/rename.rs b/src/tools/clippy/tests/ui/rename.rs
index 341c003b9df..d2010d71d2c 100644
--- a/src/tools/clippy/tests/ui/rename.rs
+++ b/src/tools/clippy/tests/ui/rename.rs
@@ -54,6 +54,7 @@
 #![warn(clippy::if_let_some_result)]
 #![warn(clippy::disallowed_type)]
 #![warn(clippy::disallowed_method)]
+#![warn(clippy::ref_in_deref)]
 // uplifted lints
 #![warn(clippy::invalid_ref)]
 #![warn(clippy::into_iter_on_array)]
diff --git a/src/tools/clippy/tests/ui/rename.stderr b/src/tools/clippy/tests/ui/rename.stderr
index cdec2808f1d..45cb8b786f5 100644
--- a/src/tools/clippy/tests/ui/rename.stderr
+++ b/src/tools/clippy/tests/ui/rename.stderr
@@ -138,59 +138,65 @@ error: lint `clippy::disallowed_method` has been renamed to `clippy::disallowed_
 LL | #![warn(clippy::disallowed_method)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::disallowed_methods`
 
+error: lint `clippy::ref_in_deref` has been renamed to `clippy::needless_borrow`
+  --> $DIR/rename.rs:57:9
+   |
+LL | #![warn(clippy::ref_in_deref)]
+   |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::needless_borrow`
+
 error: lint `clippy::invalid_ref` has been renamed to `invalid_value`
-  --> $DIR/rename.rs:58:9
+  --> $DIR/rename.rs:59:9
    |
 LL | #![warn(clippy::invalid_ref)]
    |         ^^^^^^^^^^^^^^^^^^^ help: use the new name: `invalid_value`
 
 error: lint `clippy::into_iter_on_array` has been renamed to `array_into_iter`
-  --> $DIR/rename.rs:59:9
+  --> $DIR/rename.rs:60:9
    |
 LL | #![warn(clippy::into_iter_on_array)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `array_into_iter`
 
 error: lint `clippy::unused_label` has been renamed to `unused_labels`
-  --> $DIR/rename.rs:60:9
+  --> $DIR/rename.rs:61:9
    |
 LL | #![warn(clippy::unused_label)]
    |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `unused_labels`
 
 error: lint `clippy::drop_bounds` has been renamed to `drop_bounds`
-  --> $DIR/rename.rs:61:9
+  --> $DIR/rename.rs:62:9
    |
 LL | #![warn(clippy::drop_bounds)]
    |         ^^^^^^^^^^^^^^^^^^^ help: use the new name: `drop_bounds`
 
 error: lint `clippy::temporary_cstring_as_ptr` has been renamed to `temporary_cstring_as_ptr`
-  --> $DIR/rename.rs:62:9
+  --> $DIR/rename.rs:63:9
    |
 LL | #![warn(clippy::temporary_cstring_as_ptr)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `temporary_cstring_as_ptr`
 
 error: lint `clippy::panic_params` has been renamed to `non_fmt_panics`
-  --> $DIR/rename.rs:63:9
+  --> $DIR/rename.rs:64:9
    |
 LL | #![warn(clippy::panic_params)]
    |         ^^^^^^^^^^^^^^^^^^^^ help: use the new name: `non_fmt_panics`
 
 error: lint `clippy::unknown_clippy_lints` has been renamed to `unknown_lints`
-  --> $DIR/rename.rs:64:9
+  --> $DIR/rename.rs:65:9
    |
 LL | #![warn(clippy::unknown_clippy_lints)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `unknown_lints`
 
 error: lint `clippy::invalid_atomic_ordering` has been renamed to `invalid_atomic_ordering`
-  --> $DIR/rename.rs:65:9
+  --> $DIR/rename.rs:66:9
    |
 LL | #![warn(clippy::invalid_atomic_ordering)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `invalid_atomic_ordering`
 
 error: lint `clippy::mem_discriminant_non_enum` has been renamed to `enum_intrinsics_non_enums`
-  --> $DIR/rename.rs:66:9
+  --> $DIR/rename.rs:67:9
    |
 LL | #![warn(clippy::mem_discriminant_non_enum)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `enum_intrinsics_non_enums`
 
-error: aborting due to 32 previous errors
+error: aborting due to 33 previous errors
 
diff --git a/src/tools/clippy/tests/ui/search_is_some_fixable_none.rs b/src/tools/clippy/tests/ui/search_is_some_fixable_none.rs
index 778f4f6fa25..767518ab0c0 100644
--- a/src/tools/clippy/tests/ui/search_is_some_fixable_none.rs
+++ b/src/tools/clippy/tests/ui/search_is_some_fixable_none.rs
@@ -189,7 +189,7 @@ mod issue7392 {
         let _ = [&(&1, 2), &(&3, 4), &(&5, 4)].iter().find(|&(&x, y)| x == *y).is_none();
     }
 
-    fn test_string_1(s: &String) -> bool {
+    fn test_string_1(s: &str) -> bool {
         s.is_empty()
     }
 
diff --git a/src/tools/clippy/tests/ui/search_is_some_fixable_none.stderr b/src/tools/clippy/tests/ui/search_is_some_fixable_none.stderr
index 7c5e5eb589c..933ce5cf42d 100644
--- a/src/tools/clippy/tests/ui/search_is_some_fixable_none.stderr
+++ b/src/tools/clippy/tests/ui/search_is_some_fixable_none.stderr
@@ -251,14 +251,6 @@ error: called `is_none()` after searching an `Iterator` with `find`
 LL |         let _ = [&(&1, 2), &(&3, 4), &(&5, 4)].iter().find(|&(&x, y)| x == *y).is_none();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `!_.any()` instead: `![&(&1, 2), &(&3, 4), &(&5, 4)].iter().any(|(&x, y)| x == *y)`
 
-error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/search_is_some_fixable_none.rs:192:25
-   |
-LL |     fn test_string_1(s: &String) -> bool {
-   |                         ^^^^^^^ help: change this to: `&str`
-   |
-   = note: `-D clippy::ptr-arg` implied by `-D warnings`
-
 error: called `is_none()` after searching an `Iterator` with `find`
   --> $DIR/search_is_some_fixable_none.rs:208:17
    |
@@ -289,5 +281,5 @@ error: called `is_none()` after searching an `Iterator` with `find`
 LL |         let _ = v.iter().find(|fp| test_u32_2(*fp.field)).is_none();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `!_.any()` instead: `!v.iter().any(|fp| test_u32_2(*fp.field))`
 
-error: aborting due to 44 previous errors
+error: aborting due to 43 previous errors
 
diff --git a/src/tools/clippy/tests/ui/search_is_some_fixable_some.rs b/src/tools/clippy/tests/ui/search_is_some_fixable_some.rs
index 241641fceae..77fd52e4ce7 100644
--- a/src/tools/clippy/tests/ui/search_is_some_fixable_some.rs
+++ b/src/tools/clippy/tests/ui/search_is_some_fixable_some.rs
@@ -188,7 +188,7 @@ mod issue7392 {
         let _ = [&(&1, 2), &(&3, 4), &(&5, 4)].iter().find(|&(&x, y)| x == *y).is_some();
     }
 
-    fn test_string_1(s: &String) -> bool {
+    fn test_string_1(s: &str) -> bool {
         s.is_empty()
     }
 
diff --git a/src/tools/clippy/tests/ui/search_is_some_fixable_some.stderr b/src/tools/clippy/tests/ui/search_is_some_fixable_some.stderr
index 9212c6e71ff..8b424f18ef5 100644
--- a/src/tools/clippy/tests/ui/search_is_some_fixable_some.stderr
+++ b/src/tools/clippy/tests/ui/search_is_some_fixable_some.stderr
@@ -234,14 +234,6 @@ error: called `is_some()` after searching an `Iterator` with `find`
 LL |         let _ = [&(&1, 2), &(&3, 4), &(&5, 4)].iter().find(|&(&x, y)| x == *y).is_some();
    |                                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `any()` instead: `any(|(&x, y)| x == *y)`
 
-error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/search_is_some_fixable_some.rs:191:25
-   |
-LL |     fn test_string_1(s: &String) -> bool {
-   |                         ^^^^^^^ help: change this to: `&str`
-   |
-   = note: `-D clippy::ptr-arg` implied by `-D warnings`
-
 error: called `is_some()` after searching an `Iterator` with `find`
   --> $DIR/search_is_some_fixable_some.rs:207:26
    |
@@ -272,5 +264,5 @@ error: called `is_some()` after searching an `Iterator` with `find`
 LL |         let _ = v.iter().find(|fp| test_u32_2(*fp.field)).is_some();
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `any()` instead: `any(|fp| test_u32_2(*fp.field))`
 
-error: aborting due to 44 previous errors
+error: aborting due to 43 previous errors
 
diff --git a/src/tools/clippy/tests/ui/slow_vector_initialization.rs b/src/tools/clippy/tests/ui/slow_vector_initialization.rs
index c5ae3ff769b..7e3d357ae50 100644
--- a/src/tools/clippy/tests/ui/slow_vector_initialization.rs
+++ b/src/tools/clippy/tests/ui/slow_vector_initialization.rs
@@ -53,7 +53,7 @@ fn resize_vector() {
     vec1.resize(10, 0);
 }
 
-fn do_stuff(vec: &mut Vec<u8>) {}
+fn do_stuff(vec: &mut [u8]) {}
 
 fn extend_vector_with_manipulations_between() {
     let len = 300;
diff --git a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
index 2edb202892a..21de19a2601 100644
--- a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
+++ b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.rs
@@ -1,5 +1,6 @@
 #![deny(clippy::trait_duplication_in_bounds)]
 
+use std::collections::BTreeMap;
 use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};
 
 fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
@@ -73,4 +74,25 @@ impl U for Life {
     fn f() {}
 }
 
+// should not warn
+trait Iter: Iterator {
+    fn into_group_btreemap<K, V>(self) -> BTreeMap<K, Vec<V>>
+    where
+        Self: Iterator<Item = (K, V)> + Sized,
+        K: Ord + Eq,
+    {
+        unimplemented!();
+    }
+}
+
+struct Foo {}
+
+trait FooIter: Iterator<Item = Foo> {
+    fn bar()
+    where
+        Self: Iterator<Item = Foo>,
+    {
+    }
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
index e0c7a7ec618..6f8c8e47dfb 100644
--- a/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
+++ b/src/tools/clippy/tests/ui/trait_duplication_in_bounds.stderr
@@ -1,5 +1,5 @@
 error: this trait bound is already specified in the where clause
-  --> $DIR/trait_duplication_in_bounds.rs:5:15
+  --> $DIR/trait_duplication_in_bounds.rs:6:15
    |
 LL | fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
    |               ^^^^^
@@ -12,7 +12,7 @@ LL | #![deny(clippy::trait_duplication_in_bounds)]
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in the where clause
-  --> $DIR/trait_duplication_in_bounds.rs:5:23
+  --> $DIR/trait_duplication_in_bounds.rs:6:23
    |
 LL | fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
    |                       ^^^^^^^
@@ -20,7 +20,7 @@ LL | fn bad_foo<T: Clone + Default, Z: Copy>(arg0: T, arg1: Z)
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in trait declaration
-  --> $DIR/trait_duplication_in_bounds.rs:34:15
+  --> $DIR/trait_duplication_in_bounds.rs:35:15
    |
 LL |         Self: Default;
    |               ^^^^^^^
@@ -28,7 +28,7 @@ LL |         Self: Default;
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in trait declaration
-  --> $DIR/trait_duplication_in_bounds.rs:48:15
+  --> $DIR/trait_duplication_in_bounds.rs:49:15
    |
 LL |         Self: Default + Clone;
    |               ^^^^^^^
@@ -36,7 +36,7 @@ LL |         Self: Default + Clone;
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in trait declaration
-  --> $DIR/trait_duplication_in_bounds.rs:54:15
+  --> $DIR/trait_duplication_in_bounds.rs:55:15
    |
 LL |         Self: Default + Clone;
    |               ^^^^^^^
@@ -44,7 +44,7 @@ LL |         Self: Default + Clone;
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in trait declaration
-  --> $DIR/trait_duplication_in_bounds.rs:54:25
+  --> $DIR/trait_duplication_in_bounds.rs:55:25
    |
 LL |         Self: Default + Clone;
    |                         ^^^^^
@@ -52,12 +52,20 @@ LL |         Self: Default + Clone;
    = help: consider removing this trait bound
 
 error: this trait bound is already specified in trait declaration
-  --> $DIR/trait_duplication_in_bounds.rs:57:15
+  --> $DIR/trait_duplication_in_bounds.rs:58:15
    |
 LL |         Self: Default;
    |               ^^^^^^^
    |
    = help: consider removing this trait bound
 
-error: aborting due to 7 previous errors
+error: this trait bound is already specified in trait declaration
+  --> $DIR/trait_duplication_in_bounds.rs:93:15
+   |
+LL |         Self: Iterator<Item = Foo>,
+   |               ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider removing this trait bound
+
+error: aborting due to 8 previous errors
 
diff --git a/src/tools/clippy/tests/ui/unnecessary_cast.rs b/src/tools/clippy/tests/ui/unnecessary_cast.rs
index e8f2fb46665..b77c19f2ba5 100644
--- a/src/tools/clippy/tests/ui/unnecessary_cast.rs
+++ b/src/tools/clippy/tests/ui/unnecessary_cast.rs
@@ -1,6 +1,7 @@
 #![warn(clippy::unnecessary_cast)]
 #![allow(clippy::no_effect)]
 
+#[rustfmt::skip]
 fn main() {
     // Test cast_unnecessary
     1i32 as i32;
@@ -8,6 +9,12 @@ fn main() {
     false as bool;
     &1i32 as &i32;
 
+    -1_i32 as i32;
+    - 1_i32 as i32;
+    -1f32 as f32;
+    1_i32 as i32;
+    1_f32 as f32;
+
     // macro version
     macro_rules! foo {
         ($a:ident, $b:ident) => {
diff --git a/src/tools/clippy/tests/ui/unnecessary_cast.stderr b/src/tools/clippy/tests/ui/unnecessary_cast.stderr
index 70aa448af68..a5a93c6110c 100644
--- a/src/tools/clippy/tests/ui/unnecessary_cast.stderr
+++ b/src/tools/clippy/tests/ui/unnecessary_cast.stderr
@@ -1,5 +1,5 @@
 error: casting integer literal to `i32` is unnecessary
-  --> $DIR/unnecessary_cast.rs:6:5
+  --> $DIR/unnecessary_cast.rs:7:5
    |
 LL |     1i32 as i32;
    |     ^^^^^^^^^^^ help: try: `1_i32`
@@ -7,16 +7,46 @@ LL |     1i32 as i32;
    = note: `-D clippy::unnecessary-cast` implied by `-D warnings`
 
 error: casting float literal to `f32` is unnecessary
-  --> $DIR/unnecessary_cast.rs:7:5
+  --> $DIR/unnecessary_cast.rs:8:5
    |
 LL |     1f32 as f32;
    |     ^^^^^^^^^^^ help: try: `1_f32`
 
 error: casting to the same type is unnecessary (`bool` -> `bool`)
-  --> $DIR/unnecessary_cast.rs:8:5
+  --> $DIR/unnecessary_cast.rs:9:5
    |
 LL |     false as bool;
    |     ^^^^^^^^^^^^^ help: try: `false`
 
-error: aborting due to 3 previous errors
+error: casting integer literal to `i32` is unnecessary
+  --> $DIR/unnecessary_cast.rs:12:5
+   |
+LL |     -1_i32 as i32;
+   |     ^^^^^^^^^^^^^ help: try: `-1_i32`
+
+error: casting integer literal to `i32` is unnecessary
+  --> $DIR/unnecessary_cast.rs:13:5
+   |
+LL |     - 1_i32 as i32;
+   |     ^^^^^^^^^^^^^^ help: try: `- 1_i32`
+
+error: casting float literal to `f32` is unnecessary
+  --> $DIR/unnecessary_cast.rs:14:5
+   |
+LL |     -1f32 as f32;
+   |     ^^^^^^^^^^^^ help: try: `-1_f32`
+
+error: casting integer literal to `i32` is unnecessary
+  --> $DIR/unnecessary_cast.rs:15:5
+   |
+LL |     1_i32 as i32;
+   |     ^^^^^^^^^^^^ help: try: `1_i32`
+
+error: casting float literal to `f32` is unnecessary
+  --> $DIR/unnecessary_cast.rs:16:5
+   |
+LL |     1_f32 as f32;
+   |     ^^^^^^^^^^^^ help: try: `1_f32`
+
+error: aborting due to 8 previous errors
 
diff --git a/src/tools/clippy/tests/ui/unnecessary_ref.fixed b/src/tools/clippy/tests/ui/unnecessary_ref.fixed
deleted file mode 100644
index d927bae976f..00000000000
--- a/src/tools/clippy/tests/ui/unnecessary_ref.fixed
+++ /dev/null
@@ -1,23 +0,0 @@
-// run-rustfix
-
-#![feature(stmt_expr_attributes)]
-#![allow(unused_variables, dead_code)]
-
-struct Outer {
-    inner: u32,
-}
-
-#[deny(clippy::ref_in_deref)]
-fn main() {
-    let outer = Outer { inner: 0 };
-    let inner = outer.inner;
-}
-
-struct Apple;
-impl Apple {
-    fn hello(&self) {}
-}
-struct Package(pub *const Apple);
-fn foobar(package: *const Package) {
-    unsafe { &*(*package).0 }.hello();
-}
diff --git a/src/tools/clippy/tests/ui/unnecessary_ref.rs b/src/tools/clippy/tests/ui/unnecessary_ref.rs
deleted file mode 100644
index 86bfb76ec26..00000000000
--- a/src/tools/clippy/tests/ui/unnecessary_ref.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-// run-rustfix
-
-#![feature(stmt_expr_attributes)]
-#![allow(unused_variables, dead_code)]
-
-struct Outer {
-    inner: u32,
-}
-
-#[deny(clippy::ref_in_deref)]
-fn main() {
-    let outer = Outer { inner: 0 };
-    let inner = (&outer).inner;
-}
-
-struct Apple;
-impl Apple {
-    fn hello(&self) {}
-}
-struct Package(pub *const Apple);
-fn foobar(package: *const Package) {
-    unsafe { &*(&*package).0 }.hello();
-}
diff --git a/src/tools/clippy/tests/ui/unnecessary_ref.stderr b/src/tools/clippy/tests/ui/unnecessary_ref.stderr
deleted file mode 100644
index 436f4bcf738..00000000000
--- a/src/tools/clippy/tests/ui/unnecessary_ref.stderr
+++ /dev/null
@@ -1,22 +0,0 @@
-error: creating a reference that is immediately dereferenced
-  --> $DIR/unnecessary_ref.rs:13:17
-   |
-LL |     let inner = (&outer).inner;
-   |                 ^^^^^^^^ help: try this: `outer`
-   |
-note: the lint level is defined here
-  --> $DIR/unnecessary_ref.rs:10:8
-   |
-LL | #[deny(clippy::ref_in_deref)]
-   |        ^^^^^^^^^^^^^^^^^^^^
-
-error: creating a reference that is immediately dereferenced
-  --> $DIR/unnecessary_ref.rs:22:16
-   |
-LL |     unsafe { &*(&*package).0 }.hello();
-   |                ^^^^^^^^^^^ help: try this: `(*package)`
-   |
-   = note: `-D clippy::ref-in-deref` implied by `-D warnings`
-
-error: aborting due to 2 previous errors
-
diff --git a/src/tools/clippy/tests/ui/useless_asref.fixed b/src/tools/clippy/tests/ui/useless_asref.fixed
index e356f13d087..e431661d180 100644
--- a/src/tools/clippy/tests/ui/useless_asref.fixed
+++ b/src/tools/clippy/tests/ui/useless_asref.fixed
@@ -67,7 +67,7 @@ fn not_ok() {
         foo_rslice(mrrrrrslice);
         foo_rslice(mrrrrrslice);
     }
-    #[allow(unused_parens, clippy::double_parens)]
+    #[allow(unused_parens, clippy::double_parens, clippy::needless_borrow)]
     foo_rrrrmr((&&&&MoreRef));
 
     generic_not_ok(mrslice);
diff --git a/src/tools/clippy/tests/ui/useless_asref.rs b/src/tools/clippy/tests/ui/useless_asref.rs
index 2a80291f5d8..6ae931d7aa4 100644
--- a/src/tools/clippy/tests/ui/useless_asref.rs
+++ b/src/tools/clippy/tests/ui/useless_asref.rs
@@ -67,7 +67,7 @@ fn not_ok() {
         foo_rslice(mrrrrrslice.as_ref());
         foo_rslice(mrrrrrslice);
     }
-    #[allow(unused_parens, clippy::double_parens)]
+    #[allow(unused_parens, clippy::double_parens, clippy::needless_borrow)]
     foo_rrrrmr((&&&&MoreRef).as_ref());
 
     generic_not_ok(mrslice);
diff --git a/src/tools/clippy/tests/ui/write_literal.rs b/src/tools/clippy/tests/ui/write_literal.rs
index 0a127858def..44669174411 100644
--- a/src/tools/clippy/tests/ui/write_literal.rs
+++ b/src/tools/clippy/tests/ui/write_literal.rs
@@ -7,37 +7,37 @@ fn main() {
     let mut v = Vec::new();
 
     // these should be fine
-    write!(&mut v, "Hello");
-    writeln!(&mut v, "Hello");
+    write!(v, "Hello");
+    writeln!(v, "Hello");
     let world = "world";
-    writeln!(&mut v, "Hello {}", world);
-    writeln!(&mut v, "Hello {world}", world = world);
-    writeln!(&mut v, "3 in hex is {:X}", 3);
-    writeln!(&mut v, "2 + 1 = {:.4}", 3);
-    writeln!(&mut v, "2 + 1 = {:5.4}", 3);
-    writeln!(&mut v, "Debug test {:?}", "hello, world");
-    writeln!(&mut v, "{0:8} {1:>8}", "hello", "world");
-    writeln!(&mut v, "{1:8} {0:>8}", "hello", "world");
-    writeln!(&mut v, "{foo:8} {bar:>8}", foo = "hello", bar = "world");
-    writeln!(&mut v, "{bar:8} {foo:>8}", foo = "hello", bar = "world");
-    writeln!(&mut v, "{number:>width$}", number = 1, width = 6);
-    writeln!(&mut v, "{number:>0width$}", number = 1, width = 6);
-    writeln!(&mut v, "{} of {:b} people know binary, the other half doesn't", 1, 2);
-    writeln!(&mut v, "10 / 4 is {}", 2.5);
-    writeln!(&mut v, "2 + 1 = {}", 3);
+    writeln!(v, "Hello {}", world);
+    writeln!(v, "Hello {world}", world = world);
+    writeln!(v, "3 in hex is {:X}", 3);
+    writeln!(v, "2 + 1 = {:.4}", 3);
+    writeln!(v, "2 + 1 = {:5.4}", 3);
+    writeln!(v, "Debug test {:?}", "hello, world");
+    writeln!(v, "{0:8} {1:>8}", "hello", "world");
+    writeln!(v, "{1:8} {0:>8}", "hello", "world");
+    writeln!(v, "{foo:8} {bar:>8}", foo = "hello", bar = "world");
+    writeln!(v, "{bar:8} {foo:>8}", foo = "hello", bar = "world");
+    writeln!(v, "{number:>width$}", number = 1, width = 6);
+    writeln!(v, "{number:>0width$}", number = 1, width = 6);
+    writeln!(v, "{} of {:b} people know binary, the other half doesn't", 1, 2);
+    writeln!(v, "10 / 4 is {}", 2.5);
+    writeln!(v, "2 + 1 = {}", 3);
 
     // these should throw warnings
-    write!(&mut v, "Hello {}", "world");
-    writeln!(&mut v, "Hello {} {}", world, "world");
-    writeln!(&mut v, "Hello {}", "world");
+    write!(v, "Hello {}", "world");
+    writeln!(v, "Hello {} {}", world, "world");
+    writeln!(v, "Hello {}", "world");
 
     // positional args don't change the fact
     // that we're using a literal -- this should
     // throw a warning
-    writeln!(&mut v, "{0} {1}", "hello", "world");
-    writeln!(&mut v, "{1} {0}", "hello", "world");
+    writeln!(v, "{0} {1}", "hello", "world");
+    writeln!(v, "{1} {0}", "hello", "world");
 
     // named args shouldn't change anything either
-    writeln!(&mut v, "{foo} {bar}", foo = "hello", bar = "world");
-    writeln!(&mut v, "{bar} {foo}", foo = "hello", bar = "world");
+    writeln!(v, "{foo} {bar}", foo = "hello", bar = "world");
+    writeln!(v, "{bar} {foo}", foo = "hello", bar = "world");
 }
diff --git a/src/tools/clippy/tests/ui/write_literal.stderr b/src/tools/clippy/tests/ui/write_literal.stderr
index e0297c00231..593e9493ec5 100644
--- a/src/tools/clippy/tests/ui/write_literal.stderr
+++ b/src/tools/clippy/tests/ui/write_literal.stderr
@@ -1,134 +1,134 @@
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:30:32
+  --> $DIR/write_literal.rs:30:27
    |
-LL |     write!(&mut v, "Hello {}", "world");
-   |                                ^^^^^^^
+LL |     write!(v, "Hello {}", "world");
+   |                           ^^^^^^^
    |
    = note: `-D clippy::write-literal` implied by `-D warnings`
 help: try this
    |
-LL -     write!(&mut v, "Hello {}", "world");
-LL +     write!(&mut v, "Hello world");
+LL -     write!(v, "Hello {}", "world");
+LL +     write!(v, "Hello world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:31:44
+  --> $DIR/write_literal.rs:31:39
    |
-LL |     writeln!(&mut v, "Hello {} {}", world, "world");
-   |                                            ^^^^^^^
+LL |     writeln!(v, "Hello {} {}", world, "world");
+   |                                       ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "Hello {} {}", world, "world");
-LL +     writeln!(&mut v, "Hello {} world", world);
+LL -     writeln!(v, "Hello {} {}", world, "world");
+LL +     writeln!(v, "Hello {} world", world);
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:32:34
+  --> $DIR/write_literal.rs:32:29
    |
-LL |     writeln!(&mut v, "Hello {}", "world");
-   |                                  ^^^^^^^
+LL |     writeln!(v, "Hello {}", "world");
+   |                             ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "Hello {}", "world");
-LL +     writeln!(&mut v, "Hello world");
+LL -     writeln!(v, "Hello {}", "world");
+LL +     writeln!(v, "Hello world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:37:33
+  --> $DIR/write_literal.rs:37:28
    |
-LL |     writeln!(&mut v, "{0} {1}", "hello", "world");
-   |                                 ^^^^^^^
+LL |     writeln!(v, "{0} {1}", "hello", "world");
+   |                            ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{0} {1}", "hello", "world");
-LL +     writeln!(&mut v, "hello {1}", "world");
+LL -     writeln!(v, "{0} {1}", "hello", "world");
+LL +     writeln!(v, "hello {1}", "world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:37:42
+  --> $DIR/write_literal.rs:37:37
    |
-LL |     writeln!(&mut v, "{0} {1}", "hello", "world");
-   |                                          ^^^^^^^
+LL |     writeln!(v, "{0} {1}", "hello", "world");
+   |                                     ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{0} {1}", "hello", "world");
-LL +     writeln!(&mut v, "{0} world", "hello");
+LL -     writeln!(v, "{0} {1}", "hello", "world");
+LL +     writeln!(v, "{0} world", "hello");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:38:33
+  --> $DIR/write_literal.rs:38:28
    |
-LL |     writeln!(&mut v, "{1} {0}", "hello", "world");
-   |                                 ^^^^^^^
+LL |     writeln!(v, "{1} {0}", "hello", "world");
+   |                            ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{1} {0}", "hello", "world");
-LL +     writeln!(&mut v, "{1} hello", "world");
+LL -     writeln!(v, "{1} {0}", "hello", "world");
+LL +     writeln!(v, "{1} hello", "world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:38:42
+  --> $DIR/write_literal.rs:38:37
    |
-LL |     writeln!(&mut v, "{1} {0}", "hello", "world");
-   |                                          ^^^^^^^
+LL |     writeln!(v, "{1} {0}", "hello", "world");
+   |                                     ^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{1} {0}", "hello", "world");
-LL +     writeln!(&mut v, "world {0}", "hello");
+LL -     writeln!(v, "{1} {0}", "hello", "world");
+LL +     writeln!(v, "world {0}", "hello");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:41:37
+  --> $DIR/write_literal.rs:41:32
    |
-LL |     writeln!(&mut v, "{foo} {bar}", foo = "hello", bar = "world");
-   |                                     ^^^^^^^^^^^^^
+LL |     writeln!(v, "{foo} {bar}", foo = "hello", bar = "world");
+   |                                ^^^^^^^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{foo} {bar}", foo = "hello", bar = "world");
-LL +     writeln!(&mut v, "hello {bar}", bar = "world");
+LL -     writeln!(v, "{foo} {bar}", foo = "hello", bar = "world");
+LL +     writeln!(v, "hello {bar}", bar = "world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:41:52
+  --> $DIR/write_literal.rs:41:47
    |
-LL |     writeln!(&mut v, "{foo} {bar}", foo = "hello", bar = "world");
-   |                                                    ^^^^^^^^^^^^^
+LL |     writeln!(v, "{foo} {bar}", foo = "hello", bar = "world");
+   |                                               ^^^^^^^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{foo} {bar}", foo = "hello", bar = "world");
-LL +     writeln!(&mut v, "{foo} world", foo = "hello");
+LL -     writeln!(v, "{foo} {bar}", foo = "hello", bar = "world");
+LL +     writeln!(v, "{foo} world", foo = "hello");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:42:37
+  --> $DIR/write_literal.rs:42:32
    |
-LL |     writeln!(&mut v, "{bar} {foo}", foo = "hello", bar = "world");
-   |                                     ^^^^^^^^^^^^^
+LL |     writeln!(v, "{bar} {foo}", foo = "hello", bar = "world");
+   |                                ^^^^^^^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{bar} {foo}", foo = "hello", bar = "world");
-LL +     writeln!(&mut v, "{bar} hello", bar = "world");
+LL -     writeln!(v, "{bar} {foo}", foo = "hello", bar = "world");
+LL +     writeln!(v, "{bar} hello", bar = "world");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal.rs:42:52
+  --> $DIR/write_literal.rs:42:47
    |
-LL |     writeln!(&mut v, "{bar} {foo}", foo = "hello", bar = "world");
-   |                                                    ^^^^^^^^^^^^^
+LL |     writeln!(v, "{bar} {foo}", foo = "hello", bar = "world");
+   |                                               ^^^^^^^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{bar} {foo}", foo = "hello", bar = "world");
-LL +     writeln!(&mut v, "world {foo}", foo = "hello");
+LL -     writeln!(v, "{bar} {foo}", foo = "hello", bar = "world");
+LL +     writeln!(v, "world {foo}", foo = "hello");
    | 
 
 error: aborting due to 11 previous errors
diff --git a/src/tools/clippy/tests/ui/write_literal_2.rs b/src/tools/clippy/tests/ui/write_literal_2.rs
index f341e8215e1..ba0d7be5eaa 100644
--- a/src/tools/clippy/tests/ui/write_literal_2.rs
+++ b/src/tools/clippy/tests/ui/write_literal_2.rs
@@ -6,20 +6,20 @@ use std::io::Write;
 fn main() {
     let mut v = Vec::new();
 
-    writeln!(&mut v, "{}", "{hello}");
-    writeln!(&mut v, r"{}", r"{hello}");
-    writeln!(&mut v, "{}", '\'');
-    writeln!(&mut v, "{}", '"');
-    writeln!(&mut v, r"{}", '"'); // don't lint
-    writeln!(&mut v, r"{}", '\'');
+    writeln!(v, "{}", "{hello}");
+    writeln!(v, r"{}", r"{hello}");
+    writeln!(v, "{}", '\'');
+    writeln!(v, "{}", '"');
+    writeln!(v, r"{}", '"'); // don't lint
+    writeln!(v, r"{}", '\'');
     writeln!(
-        &mut v,
+        v,
         "some {}",
         "hello \
         world!"
     );
     writeln!(
-        &mut v,
+        v,
         "some {}\
         {} \\ {}",
         "1", "2", "3",
diff --git a/src/tools/clippy/tests/ui/write_literal_2.stderr b/src/tools/clippy/tests/ui/write_literal_2.stderr
index 73c6b885813..fc40fbfa9e2 100644
--- a/src/tools/clippy/tests/ui/write_literal_2.stderr
+++ b/src/tools/clippy/tests/ui/write_literal_2.stderr
@@ -1,62 +1,62 @@
 error: literal with an empty format string
-  --> $DIR/write_literal_2.rs:9:28
+  --> $DIR/write_literal_2.rs:9:23
    |
-LL |     writeln!(&mut v, "{}", "{hello}");
-   |                            ^^^^^^^^^
+LL |     writeln!(v, "{}", "{hello}");
+   |                       ^^^^^^^^^
    |
    = note: `-D clippy::write-literal` implied by `-D warnings`
 help: try this
    |
-LL -     writeln!(&mut v, "{}", "{hello}");
-LL +     writeln!(&mut v, "{{hello}}");
+LL -     writeln!(v, "{}", "{hello}");
+LL +     writeln!(v, "{{hello}}");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal_2.rs:10:29
+  --> $DIR/write_literal_2.rs:10:24
    |
-LL |     writeln!(&mut v, r"{}", r"{hello}");
-   |                             ^^^^^^^^^^
+LL |     writeln!(v, r"{}", r"{hello}");
+   |                        ^^^^^^^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, r"{}", r"{hello}");
-LL +     writeln!(&mut v, r"{{hello}}");
+LL -     writeln!(v, r"{}", r"{hello}");
+LL +     writeln!(v, r"{{hello}}");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal_2.rs:11:28
+  --> $DIR/write_literal_2.rs:11:23
    |
-LL |     writeln!(&mut v, "{}", '/'');
-   |                            ^^^^
+LL |     writeln!(v, "{}", '/'');
+   |                       ^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{}", '/'');
-LL +     writeln!(&mut v, "'");
+LL -     writeln!(v, "{}", '/'');
+LL +     writeln!(v, "'");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal_2.rs:12:28
+  --> $DIR/write_literal_2.rs:12:23
    |
-LL |     writeln!(&mut v, "{}", '"');
-   |                            ^^^
+LL |     writeln!(v, "{}", '"');
+   |                       ^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, "{}", '"');
-LL +     writeln!(&mut v, "/"");
+LL -     writeln!(v, "{}", '"');
+LL +     writeln!(v, "/"");
    | 
 
 error: literal with an empty format string
-  --> $DIR/write_literal_2.rs:14:29
+  --> $DIR/write_literal_2.rs:14:24
    |
-LL |     writeln!(&mut v, r"{}", '/'');
-   |                             ^^^^
+LL |     writeln!(v, r"{}", '/'');
+   |                        ^^^^
    |
 help: try this
    |
-LL -     writeln!(&mut v, r"{}", '/'');
-LL +     writeln!(&mut v, r"'");
+LL -     writeln!(v, r"{}", '/'');
+LL +     writeln!(v, r"'");
    | 
 
 error: literal with an empty format string
diff --git a/src/tools/clippy/tests/ui/write_with_newline.rs b/src/tools/clippy/tests/ui/write_with_newline.rs
index 1c1b1b58402..446d6914d34 100644
--- a/src/tools/clippy/tests/ui/write_with_newline.rs
+++ b/src/tools/clippy/tests/ui/write_with_newline.rs
@@ -10,50 +10,50 @@ fn main() {
     let mut v = Vec::new();
 
     // These should fail
-    write!(&mut v, "Hello\n");
-    write!(&mut v, "Hello {}\n", "world");
-    write!(&mut v, "Hello {} {}\n", "world", "#2");
-    write!(&mut v, "{}\n", 1265);
-    write!(&mut v, "\n");
+    write!(v, "Hello\n");
+    write!(v, "Hello {}\n", "world");
+    write!(v, "Hello {} {}\n", "world", "#2");
+    write!(v, "{}\n", 1265);
+    write!(v, "\n");
 
     // These should be fine
-    write!(&mut v, "");
-    write!(&mut v, "Hello");
-    writeln!(&mut v, "Hello");
-    writeln!(&mut v, "Hello\n");
-    writeln!(&mut v, "Hello {}\n", "world");
-    write!(&mut v, "Issue\n{}", 1265);
-    write!(&mut v, "{}", 1265);
-    write!(&mut v, "\n{}", 1275);
-    write!(&mut v, "\n\n");
-    write!(&mut v, "like eof\n\n");
-    write!(&mut v, "Hello {} {}\n\n", "world", "#2");
-    writeln!(&mut v, "\ndon't\nwarn\nfor\nmultiple\nnewlines\n"); // #3126
-    writeln!(&mut v, "\nbla\n\n"); // #3126
+    write!(v, "");
+    write!(v, "Hello");
+    writeln!(v, "Hello");
+    writeln!(v, "Hello\n");
+    writeln!(v, "Hello {}\n", "world");
+    write!(v, "Issue\n{}", 1265);
+    write!(v, "{}", 1265);
+    write!(v, "\n{}", 1275);
+    write!(v, "\n\n");
+    write!(v, "like eof\n\n");
+    write!(v, "Hello {} {}\n\n", "world", "#2");
+    writeln!(v, "\ndon't\nwarn\nfor\nmultiple\nnewlines\n"); // #3126
+    writeln!(v, "\nbla\n\n"); // #3126
 
     // Escaping
-    write!(&mut v, "\\n"); // #3514
-    write!(&mut v, "\\\n"); // should fail
-    write!(&mut v, "\\\\n");
+    write!(v, "\\n"); // #3514
+    write!(v, "\\\n"); // should fail
+    write!(v, "\\\\n");
 
     // Raw strings
-    write!(&mut v, r"\n"); // #3778
+    write!(v, r"\n"); // #3778
 
     // Literal newlines should also fail
     write!(
-        &mut v,
+        v,
         "
 "
     );
     write!(
-        &mut v,
+        v,
         r"
 "
     );
 
     // Don't warn on CRLF (#4208)
-    write!(&mut v, "\r\n");
-    write!(&mut v, "foo\r\n");
-    write!(&mut v, "\\r\n"); //~ ERROR
-    write!(&mut v, "foo\rbar\n");
+    write!(v, "\r\n");
+    write!(v, "foo\r\n");
+    write!(v, "\\r\n"); //~ ERROR
+    write!(v, "foo\rbar\n");
 }
diff --git a/src/tools/clippy/tests/ui/write_with_newline.stderr b/src/tools/clippy/tests/ui/write_with_newline.stderr
index 186459e50b6..3314a2a6e24 100644
--- a/src/tools/clippy/tests/ui/write_with_newline.stderr
+++ b/src/tools/clippy/tests/ui/write_with_newline.stderr
@@ -1,81 +1,81 @@
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:13:5
    |
-LL |     write!(&mut v, "Hello/n");
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "Hello/n");
+   |     ^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::write-with-newline` implied by `-D warnings`
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "Hello/n");
-LL +     writeln!(&mut v, "Hello");
+LL -     write!(v, "Hello/n");
+LL +     writeln!(v, "Hello");
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:14:5
    |
-LL |     write!(&mut v, "Hello {}/n", "world");
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "Hello {}/n", "world");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "Hello {}/n", "world");
-LL +     writeln!(&mut v, "Hello {}", "world");
+LL -     write!(v, "Hello {}/n", "world");
+LL +     writeln!(v, "Hello {}", "world");
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:15:5
    |
-LL |     write!(&mut v, "Hello {} {}/n", "world", "#2");
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "Hello {} {}/n", "world", "#2");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "Hello {} {}/n", "world", "#2");
-LL +     writeln!(&mut v, "Hello {} {}", "world", "#2");
+LL -     write!(v, "Hello {} {}/n", "world", "#2");
+LL +     writeln!(v, "Hello {} {}", "world", "#2");
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:16:5
    |
-LL |     write!(&mut v, "{}/n", 1265);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "{}/n", 1265);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "{}/n", 1265);
-LL +     writeln!(&mut v, "{}", 1265);
+LL -     write!(v, "{}/n", 1265);
+LL +     writeln!(v, "{}", 1265);
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:17:5
    |
-LL |     write!(&mut v, "/n");
-   |     ^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "/n");
+   |     ^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "/n");
-LL +     writeln!(&mut v);
+LL -     write!(v, "/n");
+LL +     writeln!(v);
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:36:5
    |
-LL |     write!(&mut v, "//n"); // should fail
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "//n"); // should fail
+   |     ^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "//n"); // should fail
-LL +     writeln!(&mut v, "/"); // should fail
+LL -     write!(v, "//n"); // should fail
+LL +     writeln!(v, "/"); // should fail
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:43:5
    |
 LL | /     write!(
-LL | |         &mut v,
+LL | |         v,
 LL | |         "
 LL | | "
 LL | |     );
@@ -84,7 +84,7 @@ LL | |     );
 help: use `writeln!()` instead
    |
 LL ~     writeln!(
-LL |         &mut v,
+LL |         v,
 LL ~         ""
    |
 
@@ -92,7 +92,7 @@ error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:48:5
    |
 LL | /     write!(
-LL | |         &mut v,
+LL | |         v,
 LL | |         r"
 LL | | "
 LL | |     );
@@ -101,32 +101,32 @@ LL | |     );
 help: use `writeln!()` instead
    |
 LL ~     writeln!(
-LL |         &mut v,
+LL |         v,
 LL ~         r""
    |
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:57:5
    |
-LL |     write!(&mut v, "/r/n"); //~ ERROR
-   |     ^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "/r/n"); //~ ERROR
+   |     ^^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "/r/n"); //~ ERROR
-LL +     writeln!(&mut v, "/r"); //~ ERROR
+LL -     write!(v, "/r/n"); //~ ERROR
+LL +     writeln!(v, "/r"); //~ ERROR
    | 
 
 error: using `write!()` with a format string that ends in a single newline
   --> $DIR/write_with_newline.rs:58:5
    |
-LL |     write!(&mut v, "foo/rbar/n");
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     write!(v, "foo/rbar/n");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: use `writeln!()` instead
    |
-LL -     write!(&mut v, "foo/rbar/n");
-LL +     writeln!(&mut v, "foo/rbar");
+LL -     write!(v, "foo/rbar/n");
+LL +     writeln!(v, "foo/rbar");
    | 
 
 error: aborting due to 10 previous errors
diff --git a/src/tools/clippy/tests/ui/writeln_empty_string.fixed b/src/tools/clippy/tests/ui/writeln_empty_string.fixed
index c3ac15b0375..e7d94acd130 100644
--- a/src/tools/clippy/tests/ui/writeln_empty_string.fixed
+++ b/src/tools/clippy/tests/ui/writeln_empty_string.fixed
@@ -8,13 +8,13 @@ fn main() {
     let mut v = Vec::new();
 
     // These should fail
-    writeln!(&mut v);
+    writeln!(v);
 
     let mut suggestion = Vec::new();
-    writeln!(&mut suggestion);
+    writeln!(suggestion);
 
     // These should be fine
-    writeln!(&mut v);
-    writeln!(&mut v, " ");
-    write!(&mut v, "");
+    writeln!(v);
+    writeln!(v, " ");
+    write!(v, "");
 }
diff --git a/src/tools/clippy/tests/ui/writeln_empty_string.rs b/src/tools/clippy/tests/ui/writeln_empty_string.rs
index 9a8894b6c0d..662c62f0211 100644
--- a/src/tools/clippy/tests/ui/writeln_empty_string.rs
+++ b/src/tools/clippy/tests/ui/writeln_empty_string.rs
@@ -8,13 +8,13 @@ fn main() {
     let mut v = Vec::new();
 
     // These should fail
-    writeln!(&mut v, "");
+    writeln!(v, "");
 
     let mut suggestion = Vec::new();
-    writeln!(&mut suggestion, "");
+    writeln!(suggestion, "");
 
     // These should be fine
-    writeln!(&mut v);
-    writeln!(&mut v, " ");
-    write!(&mut v, "");
+    writeln!(v);
+    writeln!(v, " ");
+    write!(v, "");
 }
diff --git a/src/tools/clippy/tests/ui/writeln_empty_string.stderr b/src/tools/clippy/tests/ui/writeln_empty_string.stderr
index 99635229b3e..ac65aadfc0e 100644
--- a/src/tools/clippy/tests/ui/writeln_empty_string.stderr
+++ b/src/tools/clippy/tests/ui/writeln_empty_string.stderr
@@ -1,16 +1,16 @@
-error: using `writeln!(&mut v, "")`
+error: using `writeln!(v, "")`
   --> $DIR/writeln_empty_string.rs:11:5
    |
-LL |     writeln!(&mut v, "");
-   |     ^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(&mut v)`
+LL |     writeln!(v, "");
+   |     ^^^^^^^^^^^^^^^ help: replace it with: `writeln!(v)`
    |
    = note: `-D clippy::writeln-empty-string` implied by `-D warnings`
 
-error: using `writeln!(&mut suggestion, "")`
+error: using `writeln!(suggestion, "")`
   --> $DIR/writeln_empty_string.rs:14:5
    |
-LL |     writeln!(&mut suggestion, "");
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(&mut suggestion)`
+LL |     writeln!(suggestion, "");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(suggestion)`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/tools/clippy/util/gh-pages/index.html b/src/tools/clippy/util/gh-pages/index.html
index 5b7e61a349d..83a200ca3c4 100644
--- a/src/tools/clippy/util/gh-pages/index.html
+++ b/src/tools/clippy/util/gh-pages/index.html
@@ -522,6 +522,11 @@ Otherwise, have a great day =^.^=
                 }
 
                 scrollToLintByURL($scope);
+
+                setTimeout(function () {
+                    var el = document.getElementById('filter-input');
+                    if (el) { el.focus() }
+                }, 0);
             })
             .error(function (data) {
                 $scope.error = data;