Merge commit '2ca58e7dda' into clippyup

.github/ISSUE_TEMPLATE/new_lint.md

@@ -12,7 +12,7 @@ labels: L-lint
 
 - Kind: *See <https://github.com/rust-lang/rust-clippy/blob/master/README.md#clippy> for list of lint kinds*
 
-*What benefit of this lint over old code?*
+*What is the advantage of the recommended code over the original code*
 
 For example:
 - Remove bounce checking inserted by ...

.github/workflows/clippy_bors.yml

@@ -240,7 +240,8 @@ jobs:
         - 'Geal/nom'
         - 'rust-lang/stdarch'
         - 'serde-rs/serde'
-        - 'chronotope/chrono'
+        # FIXME: chrono currently cannot be compiled with `--all-targets`
+        # - 'chronotope/chrono'
         - 'hyperium/hyper'
         - 'rust-random/rand'
         - 'rust-lang/futures-rs'

CHANGELOG.md

@@ -1352,6 +1352,7 @@ Released 2018-09-13
 [`bad_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#bad_bit_mask
 [`bind_instead_of_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#bind_instead_of_map
 [`blacklisted_name`]: https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name
+[`blanket_clippy_restriction_lints`]: https://rust-lang.github.io/rust-clippy/master/index.html#blanket_clippy_restriction_lints
 [`blocks_in_if_conditions`]: https://rust-lang.github.io/rust-clippy/master/index.html#blocks_in_if_conditions
 [`bool_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_comparison
 [`borrow_interior_mutable_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrow_interior_mutable_const
@@ -1508,9 +1509,11 @@ Released 2018-09-13
 [`map_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_clone
 [`map_entry`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_entry
 [`map_flatten`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_flatten
+[`map_identity`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_identity
 [`map_unwrap_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_unwrap_or
 [`match_as_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_as_ref
 [`match_bool`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_bool
+[`match_like_matches_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_like_matches_macro
 [`match_on_vec_items`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_on_vec_items
 [`match_overlapping_arm`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_overlapping_arm
 [`match_ref_pats`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_ref_pats
@@ -1575,6 +1578,7 @@ Released 2018-09-13
 [`op_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#op_ref
 [`option_as_ref_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_as_ref_deref
 [`option_env_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_env_unwrap
+[`option_if_let_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_if_let_else
 [`option_map_or_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_or_none
 [`option_map_unit_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_map_unit_fn
 [`option_option`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_option
@@ -1586,6 +1590,7 @@ Released 2018-09-13
 [`panicking_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#panicking_unwrap
 [`partialeq_ne_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#partialeq_ne_impl
 [`path_buf_push_overwrite`]: https://rust-lang.github.io/rust-clippy/master/index.html#path_buf_push_overwrite
+[`pattern_type_mismatch`]: https://rust-lang.github.io/rust-clippy/master/index.html#pattern_type_mismatch
 [`possible_missing_comma`]: https://rust-lang.github.io/rust-clippy/master/index.html#possible_missing_comma
 [`precedence`]: https://rust-lang.github.io/rust-clippy/master/index.html#precedence
 [`print_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_literal
@@ -1612,6 +1617,7 @@ Released 2018-09-13
 [`redundant_static_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
 [`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
 [`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
 [`replace_consts`]: https://rust-lang.github.io/rust-clippy/master/index.html#replace_consts
 [`rest_pat_in_fully_bound_structs`]: https://rust-lang.github.io/rust-clippy/master/index.html#rest_pat_in_fully_bound_structs
 [`result_map_or_into_option`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_map_or_into_option

CONTRIBUTING.md

@@ -245,7 +245,7 @@ this to work, you will need the fix of `git subtree` available
 [here][gitgitgadget-pr].
 
 [gitgitgadget-pr]: https://github.com/gitgitgadget/git/pull/493
-[subtree]: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#external-dependencies-subtree
+[subtree]: https://rustc-dev-guide.rust-lang.org/contributing.html#external-dependencies-subtree
 [`rust-lang/rust`]: https://github.com/rust-lang/rust
 
 ## Issue and PR triage

clippy_lints/src/attrs.rs

@@ -2,8 +2,8 @@
 
 use crate::reexport::Name;
 use crate::utils::{
-    first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_sugg,
+    first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_help,
-    span_lint_and_then, without_block_comments,
+    span_lint_and_sugg, span_lint_and_then, without_block_comments,
 };
 use if_chain::if_chain;
 use rustc_ast::ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
@@ -17,7 +17,7 @@ use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::Symbol;
+use rustc_span::symbol::{Symbol, SymbolStr};
 use semver::Version;
 
 static UNIX_SYSTEMS: &[&str] = &[
@@ -182,6 +182,29 @@ declare_clippy_lint! {
     "unknown_lints for scoped Clippy lints"
 }
 
+declare_clippy_lint! {
+    /// **What it does:** Checks for `warn`/`deny`/`forbid` attributes targeting the whole clippy::restriction category.
+    ///
+    /// **Why is this bad?** Restriction lints sometimes are in contrast with other lints or even go against idiomatic rust.
+    /// These lints should only be enabled on a lint-by-lint basis and with careful consideration.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// Bad:
+    /// ```rust
+    /// #![deny(clippy::restriction)]
+    /// ```
+    ///
+    /// Good:
+    /// ```rust
+    /// #![deny(clippy::as_conversions)]
+    /// ```
+    pub BLANKET_CLIPPY_RESTRICTION_LINTS,
+    style,
+    "enabling the complete restriction group"
+}
+
 declare_clippy_lint! {
     /// **What it does:** Checks for `#[cfg_attr(rustfmt, rustfmt_skip)]` and suggests to replace it
     /// with `#[rustfmt::skip]`.
@@ -249,15 +272,17 @@ declare_lint_pass!(Attributes => [
     DEPRECATED_SEMVER,
     USELESS_ATTRIBUTE,
     UNKNOWN_CLIPPY_LINTS,
+    BLANKET_CLIPPY_RESTRICTION_LINTS,
 ]);
 
 impl<'tcx> LateLintPass<'tcx> for Attributes {
     fn check_attribute(&mut self, cx: &LateContext<'tcx>, attr: &'tcx Attribute) {
         if let Some(items) = &attr.meta_item_list() {
             if let Some(ident) = attr.ident() {
-                match &*ident.as_str() {
+                let ident = &*ident.as_str();
+                match ident {
                     "allow" | "warn" | "deny" | "forbid" => {
-                        check_clippy_lint_names(cx, items);
+                        check_clippy_lint_names(cx, ident, items);
                     },
                     _ => {},
                 }
@@ -363,38 +388,43 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
     }
 }
 
-#[allow(clippy::single_match_else)]
+fn check_clippy_lint_names(cx: &LateContext<'_>, ident: &str, items: &[NestedMetaItem]) {
-fn check_clippy_lint_names(cx: &LateContext<'_>, items: &[NestedMetaItem]) {
+    fn extract_name(lint: &NestedMetaItem) -> Option<SymbolStr> {
-    let lint_store = cx.lints();
-    for lint in items {
         if_chain! {
             if let Some(meta_item) = lint.meta_item();
             if meta_item.path.segments.len() > 1;
             if let tool_name = meta_item.path.segments[0].ident;
             if tool_name.as_str() == "clippy";
-            let name = meta_item.path.segments.last().unwrap().ident.name;
+            let lint_name = meta_item.path.segments.last().unwrap().ident.name;
-            if let CheckLintNameResult::Tool(Err((None, _))) = lint_store.check_lint_name(
-                &name.as_str(),
-                Some(tool_name.name),
-            );
             then {
+                return Some(lint_name.as_str());
+            }
+        }
+        None
+    }
+
+    let lint_store = cx.lints();
+    for lint in items {
+        if let Some(lint_name) = extract_name(lint) {
+            if let CheckLintNameResult::Tool(Err((None, _))) =
+                lint_store.check_lint_name(&lint_name, Some(sym!(clippy)))
+            {
                 span_lint_and_then(
                     cx,
                     UNKNOWN_CLIPPY_LINTS,
                     lint.span(),
-                    &format!("unknown clippy lint: clippy::{}", name),
+                    &format!("unknown clippy lint: clippy::{}", lint_name),
                     |diag| {
-                        let name_lower = name.as_str().to_lowercase();
+                        let name_lower = lint_name.to_lowercase();
-                        let symbols = lint_store.get_lints().iter().map(
+                        let symbols = lint_store
-                            |l| Symbol::intern(&l.name_lower())
+                            .get_lints()
-                        ).collect::<Vec<_>>();
+                            .iter()
-                        let sugg = find_best_match_for_name(
+                            .map(|l| Symbol::intern(&l.name_lower()))
-                            symbols.iter(),
+                            .collect::<Vec<_>>();
-                            &format!("clippy::{}", name_lower),
+                        let sugg = find_best_match_for_name(symbols.iter(), &format!("clippy::{}", name_lower), None);
-                            None,
+                        if lint_name.chars().any(char::is_uppercase)
-                        );
+                            && lint_store.find_lints(&format!("clippy::{}", name_lower)).is_ok()
-                        if name.as_str().chars().any(char::is_uppercase)
+                        {
-                            && lint_store.find_lints(&format!("clippy::{}", name_lower)).is_ok() {
                             diag.span_suggestion(
                                 lint.span(),
                                 "lowercase the lint name",
@@ -409,10 +439,19 @@ fn check_clippy_lint_names(cx: &LateContext<'_>, items: &[NestedMetaItem]) {
                                 Applicability::MachineApplicable,
                             );
                         }
-                    }
+                    },
+                );
+            } else if lint_name == "restriction" && ident != "allow" {
+                span_lint_and_help(
+                    cx,
+                    BLANKET_CLIPPY_RESTRICTION_LINTS,
+                    lint.span(),
+                    "restriction lints are not meant to be all enabled",
+                    None,
+                    "try enabling only the lints you really need",
                 );
             }
-        };
+        }
     }
 }
 
@@ -442,15 +481,14 @@ fn is_relevant_trait(cx: &LateContext<'_>, item: &TraitItem<'_>) -> bool {
 }
 
 fn is_relevant_block(cx: &LateContext<'_>, tables: &ty::TypeckTables<'_>, block: &Block<'_>) -> bool {
-    if let Some(stmt) = block.stmts.first() {
+    block.stmts.first().map_or(
-        match &stmt.kind {
+        block.expr.as_ref().map_or(false, |e| is_relevant_expr(cx, tables, e)),
+        |stmt| match &stmt.kind {
             StmtKind::Local(_) => true,
             StmtKind::Expr(expr) | StmtKind::Semi(expr) => is_relevant_expr(cx, tables, expr),
             _ => false,
-        }
+        },
-    } else {
+    )
-        block.expr.as_ref().map_or(false, |e| is_relevant_expr(cx, tables, e))
-    }
 }
 
 fn is_relevant_expr(cx: &LateContext<'_>, tables: &ty::TypeckTables<'_>, expr: &Expr<'_>) -> bool {
@@ -460,11 +498,10 @@ fn is_relevant_expr(cx: &LateContext<'_>, tables: &ty::TypeckTables<'_>, expr: &
         ExprKind::Ret(None) | ExprKind::Break(_, None) => false,
         ExprKind::Call(path_expr, _) => {
             if let ExprKind::Path(qpath) = &path_expr.kind {
-                if let Some(fun_id) = tables.qpath_res(qpath, path_expr.hir_id).opt_def_id() {
+                tables
-                    !match_def_path(cx, fun_id, &paths::BEGIN_PANIC)
+                    .qpath_res(qpath, path_expr.hir_id)
-                } else {
+                    .opt_def_id()
-                    true
+                    .map_or(true, |fun_id| !match_def_path(cx, fun_id, &paths::BEGIN_PANIC))
-                }
             } else {
                 true
             }

clippy_lints/src/await_holding_lock.rs

@@ -11,7 +11,7 @@ declare_clippy_lint! {
     /// non-async-aware MutexGuard.
     ///
     /// **Why is this bad?** The Mutex types found in syd::sync and parking_lot
-    /// are not designed to operator in an async context across await points.
+    /// are not designed to operate in an async context across await points.
     ///
     /// There are two potential solutions. One is to use an asynx-aware Mutex
     /// type. Many asynchronous foundation crates provide such a Mutex type. The

clippy_lints/src/collapsible_if.rs

@@ -115,7 +115,7 @@ fn check_collapsible_maybe_if_let(cx: &EarlyContext<'_>, else_: &ast::Expr) {
                 COLLAPSIBLE_IF,
                 block.span,
                 "this `else { if .. }` block can be collapsed",
-                "try",
+                "collapse nested if block",
                 snippet_block_with_applicability(cx, else_.span, "..", Some(block.span), &mut applicability).into_owned(),
                 applicability,
             );
@@ -142,7 +142,7 @@ fn check_collapsible_no_if_let(cx: &EarlyContext<'_>, expr: &ast::Expr, check: &
                 let rhs = Sugg::ast(cx, check_inner, "..");
                 diag.span_suggestion(
                     expr.span,
-                    "try",
+                    "collapse nested if block",
                     format!(
                         "if {} {}",
                         lhs.and(&rhs),

clippy_lints/src/comparison_chain.rs

@@ -122,8 +122,5 @@ impl<'tcx> LateLintPass<'tcx> for ComparisonChain {
 }
 
 fn kind_is_cmp(kind: BinOpKind) -> bool {
-    match kind {
+    matches!(kind, BinOpKind::Lt | BinOpKind::Gt | BinOpKind::Eq)
-        BinOpKind::Lt | BinOpKind::Gt | BinOpKind::Eq => true,
-        _ => false,
-    }
 }

clippy_lints/src/deprecated_lints.rs

@@ -153,5 +153,13 @@ declare_deprecated_lint! {
     ///
     /// **Deprecation reason:** Associated-constants are now preferred.
     pub REPLACE_CONSTS,
-    "associated-constants `MIN`/`MAX` of integers are prefer to `{min,max}_value()` and module constants"
+    "associated-constants `MIN`/`MAX` of integers are prefered to `{min,max}_value()` and module constants"
+}
+
+declare_deprecated_lint! {
+    /// **What it does:** Nothing. This lint has been deprecated.
+    ///
+    /// **Deprecation reason:** The regex! macro does not exist anymore.
+    pub REGEX_MACRO,
+    "the regex! macro has been removed from the regex crate in 2018"
 }

clippy_lints/src/dereference.rs

@@ -73,9 +73,10 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
 fn lint_deref(cx: &LateContext<'_>, method_name: &str, call_expr: &Expr<'_>, var_span: Span, expr_span: Span) {
     match method_name {
         "deref" => {
-            if cx.tcx.lang_items().deref_trait().map_or(false, |id| {
+            let impls_deref_trait = cx.tcx.lang_items().deref_trait().map_or(false, |id| {
                 implements_trait(cx, cx.tables().expr_ty(&call_expr), id, &[])
-            }) {
+            });
+            if impls_deref_trait {
                 span_lint_and_sugg(
                     cx,
                     EXPLICIT_DEREF_METHODS,
@@ -88,9 +89,10 @@ fn lint_deref(cx: &LateContext<'_>, method_name: &str, call_expr: &Expr<'_>, var
             }
         },
         "deref_mut" => {
-            if cx.tcx.lang_items().deref_mut_trait().map_or(false, |id| {
+            let impls_deref_mut_trait = cx.tcx.lang_items().deref_mut_trait().map_or(false, |id| {
                 implements_trait(cx, cx.tables().expr_ty(&call_expr), id, &[])
-            }) {
+            });
+            if impls_deref_mut_trait {
                 span_lint_and_sugg(
                     cx,
                     EXPLICIT_DEREF_METHODS,

clippy_lints/src/eq_op.rs

@@ -214,20 +214,20 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
 }
 
 fn is_valid_operator(op: BinOp) -> bool {
-    match op.node {
+    matches!(
+        op.node,
         BinOpKind::Sub
-        | BinOpKind::Div
+            | BinOpKind::Div
-        | BinOpKind::Eq
+            | BinOpKind::Eq
-        | BinOpKind::Lt
+            | BinOpKind::Lt
-        | BinOpKind::Le
+            | BinOpKind::Le
-        | BinOpKind::Gt
+            | BinOpKind::Gt
-        | BinOpKind::Ge
+            | BinOpKind::Ge
-        | BinOpKind::Ne
+            | BinOpKind::Ne
-        | BinOpKind::And
+            | BinOpKind::And
-        | BinOpKind::Or
+            | BinOpKind::Or
-        | BinOpKind::BitXor
+            | BinOpKind::BitXor
-        | BinOpKind::BitAnd
+            | BinOpKind::BitAnd
-        | BinOpKind::BitOr => true,
+            | BinOpKind::BitOr
-        _ => false,
+    )
-    }
 }

clippy_lints/src/escape.rs

@@ -105,10 +105,7 @@ fn is_argument(map: rustc_middle::hir::map::Map<'_>, id: HirId) -> bool {
         _ => return false,
     }
 
-    match map.find(map.get_parent_node(id)) {
+    matches!(map.find(map.get_parent_node(id)), Some(Node::Param(_)))
-        Some(Node::Param(_)) => true,
-        _ => false,
-    }
 }
 
 impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {

clippy_lints/src/eta_reduction.rs

@@ -175,10 +175,7 @@ fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_a
 fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
     match (&lhs.kind, &rhs.kind) {
         (ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(&t1, &t2),
-        (l, r) => match (l, r) {
+        (l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
-            (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _)) => false,
-            (_, _) => true,
-        },
     }
 }
 

clippy_lints/src/floating_point_arithmetic.rs

@@ -1,11 +1,11 @@
 use crate::consts::{
     constant, constant_simple, Constant,
-    Constant::{F32, F64},
+    Constant::{Int, F32, F64},
 };
-use crate::utils::{higher, numeric_literal, span_lint_and_sugg, sugg, SpanlessEq};
+use crate::utils::{get_parent_expr, higher, numeric_literal, span_lint_and_sugg, sugg, SpanlessEq};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Expr, ExprKind, UnOp};
+use rustc_hir::{BinOpKind, Expr, ExprKind, PathSegment, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -293,6 +293,121 @@ fn check_powf(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
     }
 }
 
+fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
+    if let Some((value, _)) = constant(cx, cx.tables(), &args[1]) {
+        if value == Int(2) {
+            if let Some(parent) = get_parent_expr(cx, expr) {
+                if let Some(grandparent) = get_parent_expr(cx, parent) {
+                    if let ExprKind::MethodCall(PathSegment { ident: method_name, .. }, _, args, _) = grandparent.kind {
+                        if method_name.as_str() == "sqrt" && detect_hypot(cx, args).is_some() {
+                            return;
+                        }
+                    }
+                }
+
+                if let ExprKind::Binary(
+                    Spanned {
+                        node: BinOpKind::Add, ..
+                    },
+                    ref lhs,
+                    ref rhs,
+                ) = parent.kind
+                {
+                    let other_addend = if lhs.hir_id == expr.hir_id { rhs } else { lhs };
+
+                    span_lint_and_sugg(
+                        cx,
+                        SUBOPTIMAL_FLOPS,
+                        parent.span,
+                        "square can be computed more efficiently",
+                        "consider using",
+                        format!(
+                            "{}.mul_add({}, {})",
+                            Sugg::hir(cx, &args[0], ".."),
+                            Sugg::hir(cx, &args[0], ".."),
+                            Sugg::hir(cx, &other_addend, ".."),
+                        ),
+                        Applicability::MachineApplicable,
+                    );
+
+                    return;
+                }
+            }
+
+            span_lint_and_sugg(
+                cx,
+                SUBOPTIMAL_FLOPS,
+                expr.span,
+                "square can be computed more efficiently",
+                "consider using",
+                format!("{} * {}", Sugg::hir(cx, &args[0], ".."), Sugg::hir(cx, &args[0], "..")),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}
+
+fn detect_hypot(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<String> {
+    if let ExprKind::Binary(
+        Spanned {
+            node: BinOpKind::Add, ..
+        },
+        ref add_lhs,
+        ref add_rhs,
+    ) = args[0].kind
+    {
+        // check if expression of the form x * x + y * y
+        if_chain! {
+            if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref lmul_lhs, ref lmul_rhs) = add_lhs.kind;
+            if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref rmul_lhs, ref rmul_rhs) = add_rhs.kind;
+            if are_exprs_equal(cx, lmul_lhs, lmul_rhs);
+            if are_exprs_equal(cx, rmul_lhs, rmul_rhs);
+            then {
+                return Some(format!("{}.hypot({})", Sugg::hir(cx, &lmul_lhs, ".."), Sugg::hir(cx, &rmul_lhs, "..")));
+            }
+        }
+
+        // check if expression of the form x.powi(2) + y.powi(2)
+        if_chain! {
+            if let ExprKind::MethodCall(
+                PathSegment { ident: lmethod_name, .. },
+                ref _lspan,
+                ref largs,
+                _
+            ) = add_lhs.kind;
+            if let ExprKind::MethodCall(
+                PathSegment { ident: rmethod_name, .. },
+                ref _rspan,
+                ref rargs,
+                _
+            ) = add_rhs.kind;
+            if lmethod_name.as_str() == "powi" && rmethod_name.as_str() == "powi";
+            if let Some((lvalue, _)) = constant(cx, cx.tables(), &largs[1]);
+            if let Some((rvalue, _)) = constant(cx, cx.tables(), &rargs[1]);
+            if Int(2) == lvalue && Int(2) == rvalue;
+            then {
+                return Some(format!("{}.hypot({})", Sugg::hir(cx, &largs[0], ".."), Sugg::hir(cx, &rargs[0], "..")));
+            }
+        }
+    }
+
+    None
+}
+
+fn check_hypot(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
+    if let Some(message) = detect_hypot(cx, args) {
+        span_lint_and_sugg(
+            cx,
+            IMPRECISE_FLOPS,
+            expr.span,
+            "hypotenuse can be computed more accurately",
+            "consider using",
+            message,
+            Applicability::MachineApplicable,
+        );
+    }
+}
+
 // TODO: Lint expressions of the form `x.exp() - y` where y > 1
 // and suggest usage of `x.exp_m1() - (y - 1)` instead
 fn check_expm1(cx: &LateContext<'_>, expr: &Expr<'_>) {
@@ -344,6 +459,14 @@ fn check_mul_add(cx: &LateContext<'_>, expr: &Expr<'_>) {
         rhs,
     ) = &expr.kind
     {
+        if let Some(parent) = get_parent_expr(cx, expr) {
+            if let ExprKind::MethodCall(PathSegment { ident: method_name, .. }, _, args, _) = parent.kind {
+                if method_name.as_str() == "sqrt" && detect_hypot(cx, args).is_some() {
+                    return;
+                }
+            }
+        }
+
         let (recv, arg1, arg2) = if let Some((inner_lhs, inner_rhs)) = is_float_mul_expr(cx, lhs) {
             (inner_lhs, inner_rhs, rhs)
         } else if let Some((inner_lhs, inner_rhs)) = is_float_mul_expr(cx, rhs) {
@@ -479,6 +602,100 @@ fn check_custom_abs(cx: &LateContext<'_>, expr: &Expr<'_>) {
     }
 }
 
+fn are_same_base_logs(cx: &LateContext<'_>, expr_a: &Expr<'_>, expr_b: &Expr<'_>) -> bool {
+    if_chain! {
+        if let ExprKind::MethodCall(PathSegment { ident: method_name_a, .. }, _, ref args_a, _) = expr_a.kind;
+        if let ExprKind::MethodCall(PathSegment { ident: method_name_b, .. }, _, ref args_b, _) = expr_b.kind;
+        then {
+            return method_name_a.as_str() == method_name_b.as_str() &&
+                args_a.len() == args_b.len() &&
+                (
+                    ["ln", "log2", "log10"].contains(&&*method_name_a.as_str()) ||
+                    method_name_a.as_str() == "log" && args_a.len() == 2 && are_exprs_equal(cx, &args_a[1], &args_b[1])
+                );
+        }
+    }
+
+    false
+}
+
+fn check_log_division(cx: &LateContext<'_>, expr: &Expr<'_>) {
+    // check if expression of the form x.logN() / y.logN()
+    if_chain! {
+        if let ExprKind::Binary(
+            Spanned {
+                node: BinOpKind::Div, ..
+            },
+            lhs,
+            rhs,
+        ) = &expr.kind;
+        if are_same_base_logs(cx, lhs, rhs);
+        if let ExprKind::MethodCall(_, _, ref largs, _) = lhs.kind;
+        if let ExprKind::MethodCall(_, _, ref rargs, _) = rhs.kind;
+        then {
+            span_lint_and_sugg(
+                cx,
+                SUBOPTIMAL_FLOPS,
+                expr.span,
+                "log base can be expressed more clearly",
+                "consider using",
+                format!("{}.log({})", Sugg::hir(cx, &largs[0], ".."), Sugg::hir(cx, &rargs[0], ".."),),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}
+
+fn check_radians(cx: &LateContext<'_>, expr: &Expr<'_>) {
+    if_chain! {
+        if let ExprKind::Binary(
+            Spanned {
+                node: BinOpKind::Div, ..
+            },
+            div_lhs,
+            div_rhs,
+        ) = &expr.kind;
+        if let ExprKind::Binary(
+            Spanned {
+                node: BinOpKind::Mul, ..
+            },
+            mul_lhs,
+            mul_rhs,
+        ) = &div_lhs.kind;
+        if let Some((rvalue, _)) = constant(cx, cx.tables(), div_rhs);
+        if let Some((lvalue, _)) = constant(cx, cx.tables(), mul_rhs);
+        then {
+            // TODO: also check for constant values near PI/180 or 180/PI
+            if (F32(f32_consts::PI) == rvalue || F64(f64_consts::PI) == rvalue) &&
+               (F32(180_f32) == lvalue || F64(180_f64) == lvalue)
+            {
+                span_lint_and_sugg(
+                    cx,
+                    SUBOPTIMAL_FLOPS,
+                    expr.span,
+                    "conversion to degrees can be done more accurately",
+                    "consider using",
+                    format!("{}.to_degrees()", Sugg::hir(cx, &mul_lhs, "..")),
+                    Applicability::MachineApplicable,
+                );
+            } else if
+                (F32(180_f32) == rvalue || F64(180_f64) == rvalue) &&
+                (F32(f32_consts::PI) == lvalue || F64(f64_consts::PI) == lvalue)
+            {
+                span_lint_and_sugg(
+                    cx,
+                    SUBOPTIMAL_FLOPS,
+                    expr.span,
+                    "conversion to radians can be done more accurately",
+                    "consider using",
+                    format!("{}.to_radians()", Sugg::hir(cx, &mul_lhs, "..")),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+    }
+}
+
 impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if let ExprKind::MethodCall(ref path, _, args, _) = &expr.kind {
@@ -489,6 +706,8 @@ impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic {
                     "ln" => check_ln1p(cx, expr, args),
                     "log" => check_log_base(cx, expr, args),
                     "powf" => check_powf(cx, expr, args),
+                    "powi" => check_powi(cx, expr, args),
+                    "sqrt" => check_hypot(cx, expr, args),
                     _ => {},
                 }
             }
@@ -496,6 +715,8 @@ impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic {
             check_expm1(cx, expr);
             check_mul_add(cx, expr);
             check_custom_abs(cx, expr);
+            check_log_division(cx, expr);
+            check_radians(cx, expr);
         }
     }
 }

clippy_lints/src/formatting.rs

@@ -305,18 +305,10 @@ fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
 }
 
 fn is_block(expr: &Expr) -> bool {
-    if let ExprKind::Block(..) = expr.kind {
+    matches!(expr.kind, ExprKind::Block(..))
-        true
-    } else {
-        false
-    }
 }
 
 /// Check if the expression is an `if` or `if let`
 fn is_if(expr: &Expr) -> bool {
-    if let ExprKind::If(..) = expr.kind {
+    matches!(expr.kind, ExprKind::If(..))
-        true
-    } else {
-        false
-    }
 }

clippy_lints/src/functions.rs

@@ -645,13 +645,7 @@ fn is_mutated_static(cx: &LateContext<'_>, e: &hir::Expr<'_>) -> bool {
     use hir::ExprKind::{Field, Index, Path};
 
     match e.kind {
-        Path(ref qpath) => {
+        Path(ref qpath) => !matches!(qpath_res(cx, qpath, e.hir_id), Res::Local(_)),
-            if let Res::Local(_) = qpath_res(cx, qpath, e.hir_id) {
-                false
-            } else {
-                true
-            }
-        },
         Field(ref inner, _) | Index(ref inner, _) => is_mutated_static(cx, inner),
         _ => false,
     }

clippy_lints/src/if_let_mutex.rs

@@ -135,13 +135,10 @@ impl<'tcx> Visitor<'tcx> for ArmVisitor<'_, 'tcx> {
     }
 }
 
-impl<'tcx> ArmVisitor<'_, 'tcx> {
+impl<'tcx, 'l> ArmVisitor<'tcx, 'l> {
     fn same_mutex(&self, cx: &LateContext<'_>, op_mutex: &Expr<'_>) -> bool {
-        if let Some(arm_mutex) = self.found_mutex {
+        self.found_mutex
-            SpanlessEq::new(cx).eq_expr(op_mutex, arm_mutex)
+            .map_or(false, |arm_mutex| SpanlessEq::new(cx).eq_expr(op_mutex, arm_mutex))
-        } else {
-            false
-        }
     }
 }
 

clippy_lints/src/len_zero.rs

@@ -302,16 +302,12 @@ fn has_is_empty(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
 
     let ty = &walk_ptrs_ty(cx.tables().expr_ty(expr));
     match ty.kind {
-        ty::Dynamic(ref tt, ..) => {
+        ty::Dynamic(ref tt, ..) => tt.principal().map_or(false, |principal| {
-            if let Some(principal) = tt.principal() {
+            cx.tcx
-                cx.tcx
+                .associated_items(principal.def_id())
-                    .associated_items(principal.def_id())
+                .in_definition_order()
-                    .in_definition_order()
+                .any(|item| is_is_empty(cx, &item))
-                    .any(|item| is_is_empty(cx, &item))
+        }),
-            } else {
-                false
-            }
-        },
         ty::Projection(ref proj) => has_is_empty_impl(cx, proj.item_def_id),
         ty::Adt(id, _) => has_is_empty_impl(cx, id.did),
         ty::Array(..) | ty::Slice(..) | ty::Str => true,

clippy_lints/src/let_and_return.rs

@@ -1,6 +1,5 @@
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{Block, Expr, ExprKind, PatKind, StmtKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
@@ -9,7 +8,7 @@ use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
-use crate::utils::{in_macro, match_qpath, snippet_opt, span_lint_and_then};
+use crate::utils::{fn_def_id, in_macro, match_qpath, snippet_opt, span_lint_and_then};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for `let`-bindings, which are subsequently
@@ -97,22 +96,6 @@ struct BorrowVisitor<'a, 'tcx> {
     borrows: bool,
 }
 
-impl BorrowVisitor<'_, '_> {
-    fn fn_def_id(&self, expr: &Expr<'_>) -> Option<DefId> {
-        match &expr.kind {
-            ExprKind::MethodCall(..) => self.cx.tables().type_dependent_def_id(expr.hir_id),
-            ExprKind::Call(
-                Expr {
-                    kind: ExprKind::Path(qpath),
-                    ..
-                },
-                ..,
-            ) => self.cx.qpath_res(qpath, expr.hir_id).opt_def_id(),
-            _ => None,
-        }
-    }
-}
-
 impl<'tcx> Visitor<'tcx> for BorrowVisitor<'_, 'tcx> {
     type Map = Map<'tcx>;
 
@@ -121,7 +104,7 @@ impl<'tcx> Visitor<'tcx> for BorrowVisitor<'_, 'tcx> {
             return;
         }
 
-        if let Some(def_id) = self.fn_def_id(expr) {
+        if let Some(def_id) = fn_def_id(self.cx, expr) {
             self.borrows = self
                 .cx
                 .tcx

clippy_lints/src/lib.rs

@@ -229,6 +229,7 @@ mod main_recursion;
 mod manual_async_fn;
 mod manual_non_exhaustive;
 mod map_clone;
+mod map_identity;
 mod map_unit_fn;
 mod match_on_vec_items;
 mod matches;
@@ -263,10 +264,12 @@ mod non_copy_const;
 mod non_expressive_names;
 mod open_options;
 mod option_env_unwrap;
+mod option_if_let_else;
 mod overflow_check_conditional;
 mod panic_unimplemented;
 mod partialeq_ne_impl;
 mod path_buf_push_overwrite;
+mod pattern_type_mismatch;
 mod precedence;
 mod ptr;
 mod ptr_offset_with_cast;
@@ -274,11 +277,11 @@ mod question_mark;
 mod ranges;
 mod redundant_clone;
 mod redundant_field_names;
-mod redundant_pattern_matching;
 mod redundant_pub_crate;
 mod redundant_static_lifetimes;
 mod reference;
 mod regex;
+mod repeat_once;
 mod returns;
 mod serde_api;
 mod shadow;
@@ -459,7 +462,11 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     );
     store.register_removed(
         "clippy::replace_consts",
-        "associated-constants `MIN`/`MAX` of integers are prefer to `{min,max}_value()` and module constants",
+        "associated-constants `MIN`/`MAX` of integers are prefered to `{min,max}_value()` and module constants",
+    );
+    store.register_removed(
+        "clippy::regex_macro",
+        "the regex! macro has been removed from the regex crate in 2018",
     );
     // end deprecated lints, do not remove this comment, it’s used in `update_lints`
 
@@ -473,6 +480,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &assign_ops::ASSIGN_OP_PATTERN,
         &assign_ops::MISREFACTORED_ASSIGN_OP,
         &atomic_ordering::INVALID_ATOMIC_ORDERING,
+        &attrs::BLANKET_CLIPPY_RESTRICTION_LINTS,
         &attrs::DEPRECATED_CFG_ATTR,
         &attrs::DEPRECATED_SEMVER,
         &attrs::EMPTY_LINE_AFTER_OUTER_ATTR,
@@ -608,17 +616,20 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &manual_async_fn::MANUAL_ASYNC_FN,
         &manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE,
         &map_clone::MAP_CLONE,
+        &map_identity::MAP_IDENTITY,
         &map_unit_fn::OPTION_MAP_UNIT_FN,
         &map_unit_fn::RESULT_MAP_UNIT_FN,
         &match_on_vec_items::MATCH_ON_VEC_ITEMS,
         &matches::INFALLIBLE_DESTRUCTURING_MATCH,
         &matches::MATCH_AS_REF,
         &matches::MATCH_BOOL,
+        &matches::MATCH_LIKE_MATCHES_MACRO,
         &matches::MATCH_OVERLAPPING_ARM,
         &matches::MATCH_REF_PATS,
         &matches::MATCH_SINGLE_BINDING,
         &matches::MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
         &matches::MATCH_WILD_ERR_ARM,
+        &matches::REDUNDANT_PATTERN_MATCHING,
         &matches::REST_PAT_IN_FULLY_BOUND_STRUCTS,
         &matches::SINGLE_MATCH,
         &matches::SINGLE_MATCH_ELSE,
@@ -726,6 +737,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &non_expressive_names::SIMILAR_NAMES,
         &open_options::NONSENSICAL_OPEN_OPTIONS,
         &option_env_unwrap::OPTION_ENV_UNWRAP,
+        &option_if_let_else::OPTION_IF_LET_ELSE,
         &overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL,
         &panic_unimplemented::PANIC,
         &panic_unimplemented::PANIC_PARAMS,
@@ -734,6 +746,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &panic_unimplemented::UNREACHABLE,
         &partialeq_ne_impl::PARTIALEQ_NE_IMPL,
         &path_buf_push_overwrite::PATH_BUF_PUSH_OVERWRITE,
+        &pattern_type_mismatch::PATTERN_TYPE_MISMATCH,
         &precedence::PRECEDENCE,
         &ptr::CMP_NULL,
         &ptr::MUT_FROM_REF,
@@ -746,14 +759,13 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &ranges::REVERSED_EMPTY_RANGES,
         &redundant_clone::REDUNDANT_CLONE,
         &redundant_field_names::REDUNDANT_FIELD_NAMES,
-        &redundant_pattern_matching::REDUNDANT_PATTERN_MATCHING,
         &redundant_pub_crate::REDUNDANT_PUB_CRATE,
         &redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES,
         &reference::DEREF_ADDROF,
         &reference::REF_IN_DEREF,
         &regex::INVALID_REGEX,
-        &regex::REGEX_MACRO,
         &regex::TRIVIAL_REGEX,
+        &repeat_once::REPEAT_ONCE,
         &returns::NEEDLESS_RETURN,
         &returns::UNUSED_UNIT,
         &serde_api::SERDE_API_MISUSE,
@@ -946,7 +958,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box missing_doc::MissingDoc::new());
     store.register_late_pass(|| box missing_inline::MissingInline);
     store.register_late_pass(|| box if_let_some_result::OkIfLet);
-    store.register_late_pass(|| box redundant_pattern_matching::RedundantPatternMatching);
     store.register_late_pass(|| box partialeq_ne_impl::PartialEqNeImpl);
     store.register_late_pass(|| box unused_io_amount::UnusedIoAmount);
     let enum_variant_size_threshold = conf.enum_variant_size_threshold;
@@ -990,7 +1001,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box checked_conversions::CheckedConversions);
     store.register_late_pass(|| box integer_division::IntegerDivision);
     store.register_late_pass(|| box inherent_to_string::InherentToString);
-    store.register_late_pass(|| box trait_bounds::TraitBounds);
+    let max_trait_bounds = conf.max_trait_bounds;
+    store.register_late_pass(move || box trait_bounds::TraitBounds::new(max_trait_bounds));
     store.register_late_pass(|| box comparison_chain::ComparisonChain);
     store.register_late_pass(|| box mut_key::MutableKeyType);
     store.register_late_pass(|| box modulo_arithmetic::ModuloArithmetic);
@@ -1027,7 +1039,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     let array_size_threshold = conf.array_size_threshold;
     store.register_late_pass(move || box large_stack_arrays::LargeStackArrays::new(array_size_threshold));
     store.register_late_pass(move || box large_const_arrays::LargeConstArrays::new(array_size_threshold));
-    store.register_late_pass(move || box floating_point_arithmetic::FloatingPointArithmetic);
+    store.register_late_pass(|| box floating_point_arithmetic::FloatingPointArithmetic);
     store.register_early_pass(|| box as_conversions::AsConversions);
     store.register_early_pass(|| box utils::internal_lints::ProduceIce);
     store.register_late_pass(|| box let_underscore::LetUnderscore);
@@ -1043,6 +1055,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box redundant_pub_crate::RedundantPubCrate::default());
     store.register_late_pass(|| box unnamed_address::UnnamedAddress);
     store.register_late_pass(|| box dereference::Dereferencing);
+    store.register_late_pass(|| box option_if_let_else::OptionIfLetElse);
     store.register_late_pass(|| box future_not_send::FutureNotSend);
     store.register_late_pass(|| box utils::internal_lints::CollapsibleCalls);
     store.register_late_pass(|| box if_let_mutex::IfLetMutex);
@@ -1057,6 +1070,9 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     });
     store.register_early_pass(|| box unnested_or_patterns::UnnestedOrPatterns);
     store.register_late_pass(|| box macro_use::MacroUseImports::default());
+    store.register_late_pass(|| box map_identity::MapIdentity);
+    store.register_late_pass(|| box pattern_type_mismatch::PatternTypeMismatch);
+    store.register_late_pass(|| box repeat_once::RepeatOnce);
 
     store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
         LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@@ -1090,6 +1106,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&panic_unimplemented::TODO),
         LintId::of(&panic_unimplemented::UNIMPLEMENTED),
         LintId::of(&panic_unimplemented::UNREACHABLE),
+        LintId::of(&pattern_type_mismatch::PATTERN_TYPE_MISMATCH),
         LintId::of(&shadow::SHADOW_REUSE),
         LintId::of(&shadow::SHADOW_SAME),
         LintId::of(&strings::STRING_ADD),
@@ -1146,6 +1163,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&needless_continue::NEEDLESS_CONTINUE),
         LintId::of(&needless_pass_by_value::NEEDLESS_PASS_BY_VALUE),
         LintId::of(&non_expressive_names::SIMILAR_NAMES),
+        LintId::of(&option_if_let_else::OPTION_IF_LET_ELSE),
+        LintId::of(&ranges::RANGE_MINUS_ONE),
         LintId::of(&ranges::RANGE_PLUS_ONE),
         LintId::of(&shadow::SHADOW_UNRELATED),
         LintId::of(&strings::STRING_ADD_ASSIGN),
@@ -1186,6 +1205,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&assign_ops::ASSIGN_OP_PATTERN),
         LintId::of(&assign_ops::MISREFACTORED_ASSIGN_OP),
         LintId::of(&atomic_ordering::INVALID_ATOMIC_ORDERING),
+        LintId::of(&attrs::BLANKET_CLIPPY_RESTRICTION_LINTS),
         LintId::of(&attrs::DEPRECATED_CFG_ATTR),
         LintId::of(&attrs::DEPRECATED_SEMVER),
         LintId::of(&attrs::MISMATCHED_TARGET_OS),
@@ -1273,13 +1293,16 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&manual_async_fn::MANUAL_ASYNC_FN),
         LintId::of(&manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
         LintId::of(&map_clone::MAP_CLONE),
+        LintId::of(&map_identity::MAP_IDENTITY),
         LintId::of(&map_unit_fn::OPTION_MAP_UNIT_FN),
         LintId::of(&map_unit_fn::RESULT_MAP_UNIT_FN),
         LintId::of(&matches::INFALLIBLE_DESTRUCTURING_MATCH),
         LintId::of(&matches::MATCH_AS_REF),
+        LintId::of(&matches::MATCH_LIKE_MATCHES_MACRO),
         LintId::of(&matches::MATCH_OVERLAPPING_ARM),
         LintId::of(&matches::MATCH_REF_PATS),
         LintId::of(&matches::MATCH_SINGLE_BINDING),
+        LintId::of(&matches::REDUNDANT_PATTERN_MATCHING),
         LintId::of(&matches::SINGLE_MATCH),
         LintId::of(&matches::WILDCARD_IN_OR_PATTERNS),
         LintId::of(&mem_discriminant::MEM_DISCRIMINANT_NON_ENUM),
@@ -1364,18 +1387,16 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&ptr::PTR_ARG),
         LintId::of(&ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
         LintId::of(&question_mark::QUESTION_MARK),
-        LintId::of(&ranges::RANGE_MINUS_ONE),
         LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
         LintId::of(&ranges::REVERSED_EMPTY_RANGES),
         LintId::of(&redundant_clone::REDUNDANT_CLONE),
         LintId::of(&redundant_field_names::REDUNDANT_FIELD_NAMES),
-        LintId::of(&redundant_pattern_matching::REDUNDANT_PATTERN_MATCHING),
         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(&regex::REGEX_MACRO),
         LintId::of(&regex::TRIVIAL_REGEX),
+        LintId::of(&repeat_once::REPEAT_ONCE),
         LintId::of(&returns::NEEDLESS_RETURN),
         LintId::of(&returns::UNUSED_UNIT),
         LintId::of(&serde_api::SERDE_API_MISUSE),
@@ -1437,6 +1458,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_group(true, "clippy::style", Some("clippy_style"), vec![
         LintId::of(&assertions_on_constants::ASSERTIONS_ON_CONSTANTS),
         LintId::of(&assign_ops::ASSIGN_OP_PATTERN),
+        LintId::of(&attrs::BLANKET_CLIPPY_RESTRICTION_LINTS),
         LintId::of(&attrs::UNKNOWN_CLIPPY_LINTS),
         LintId::of(&bit_mask::VERBOSE_BIT_MASK),
         LintId::of(&blacklisted_name::BLACKLISTED_NAME),
@@ -1470,8 +1492,10 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
         LintId::of(&map_clone::MAP_CLONE),
         LintId::of(&matches::INFALLIBLE_DESTRUCTURING_MATCH),
+        LintId::of(&matches::MATCH_LIKE_MATCHES_MACRO),
         LintId::of(&matches::MATCH_OVERLAPPING_ARM),
         LintId::of(&matches::MATCH_REF_PATS),
+        LintId::of(&matches::REDUNDANT_PATTERN_MATCHING),
         LintId::of(&matches::SINGLE_MATCH),
         LintId::of(&mem_replace::MEM_REPLACE_OPTION_WITH_NONE),
         LintId::of(&mem_replace::MEM_REPLACE_WITH_DEFAULT),
@@ -1508,9 +1532,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&ptr::PTR_ARG),
         LintId::of(&question_mark::QUESTION_MARK),
         LintId::of(&redundant_field_names::REDUNDANT_FIELD_NAMES),
-        LintId::of(&redundant_pattern_matching::REDUNDANT_PATTERN_MATCHING),
         LintId::of(&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
-        LintId::of(&regex::REGEX_MACRO),
         LintId::of(&regex::TRIVIAL_REGEX),
         LintId::of(&returns::NEEDLESS_RETURN),
         LintId::of(&returns::UNUSED_UNIT),
@@ -1550,6 +1572,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&loops::EXPLICIT_COUNTER_LOOP),
         LintId::of(&loops::MUT_RANGE_BOUND),
         LintId::of(&loops::WHILE_LET_LOOP),
+        LintId::of(&map_identity::MAP_IDENTITY),
         LintId::of(&map_unit_fn::OPTION_MAP_UNIT_FN),
         LintId::of(&map_unit_fn::RESULT_MAP_UNIT_FN),
         LintId::of(&matches::MATCH_AS_REF),
@@ -1580,10 +1603,10 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&partialeq_ne_impl::PARTIALEQ_NE_IMPL),
         LintId::of(&precedence::PRECEDENCE),
         LintId::of(&ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
-        LintId::of(&ranges::RANGE_MINUS_ONE),
         LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
         LintId::of(&reference::DEREF_ADDROF),
         LintId::of(&reference::REF_IN_DEREF),
+        LintId::of(&repeat_once::REPEAT_ONCE),
         LintId::of(&swap::MANUAL_SWAP),
         LintId::of(&temporary_assignment::TEMPORARY_ASSIGNMENT),
         LintId::of(&transmute::CROSSPOINTER_TRANSMUTE),

clippy_lints/src/lifetimes.rs

@@ -129,10 +129,10 @@ fn check_fn_inner<'tcx>(
     }
 
     let mut bounds_lts = Vec::new();
-    let types = generics.params.iter().filter(|param| match param.kind {
+    let types = generics
-        GenericParamKind::Type { .. } => true,
+        .params
-        _ => false,
+        .iter()
-    });
+        .filter(|param| matches!(param.kind, GenericParamKind::Type { .. }));
     for typ in types {
         for bound in typ.bounds {
             let mut visitor = RefVisitor::new(cx);
@@ -337,10 +337,10 @@ impl<'a, 'tcx> RefVisitor<'a, 'tcx> {
     fn collect_anonymous_lifetimes(&mut self, qpath: &QPath<'_>, ty: &Ty<'_>) {
         if let Some(ref last_path_segment) = last_path_segment(qpath).args {
             if !last_path_segment.parenthesized
-                && !last_path_segment.args.iter().any(|arg| match arg {
+                && !last_path_segment
-                    GenericArg::Lifetime(_) => true,
+                    .args
-                    _ => false,
+                    .iter()
-                })
+                    .any(|arg| matches!(arg, GenericArg::Lifetime(_)))
             {
                 let hir_id = ty.hir_id;
                 match self.cx.qpath_res(qpath, hir_id) {

clippy_lints/src/literal_representation.rs

@@ -264,10 +264,13 @@ impl LiteralDigitGrouping {
 
         let (part, mistyped_suffixes, missing_char) = if let Some((_, exponent)) = &mut num_lit.exponent {
             (exponent, &["32", "64"][..], 'f')
-        } else if let Some(fraction) = &mut num_lit.fraction {
-            (fraction, &["32", "64"][..], 'f')
         } else {
-            (&mut num_lit.integer, &["8", "16", "32", "64"][..], 'i')
+            num_lit
+                .fraction
+                .as_mut()
+                .map_or((&mut num_lit.integer, &["8", "16", "32", "64"][..], 'i'), |fraction| {
+                    (fraction, &["32", "64"][..], 'f')
+                })
         };
 
         let mut split = part.rsplit('_');

clippy_lints/src/loops.rs

@@ -686,13 +686,9 @@ fn never_loop_expr(expr: &Expr<'_>, main_loop_id: HirId) -> NeverLoopResult {
                 NeverLoopResult::AlwaysBreak
             }
         },
-        ExprKind::Break(_, ref e) | ExprKind::Ret(ref e) => {
+        ExprKind::Break(_, ref e) | ExprKind::Ret(ref e) => e.as_ref().map_or(NeverLoopResult::AlwaysBreak, |e| {
-            if let Some(ref e) = *e {
+            combine_seq(never_loop_expr(e, main_loop_id), NeverLoopResult::AlwaysBreak)
-                combine_seq(never_loop_expr(e, main_loop_id), NeverLoopResult::AlwaysBreak)
+        }),
-            } else {
-                NeverLoopResult::AlwaysBreak
-            }
-        },
         ExprKind::InlineAsm(ref asm) => asm
             .operands
             .iter()
@@ -1881,13 +1877,9 @@ fn is_ref_iterable_type(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
 fn is_iterable_array<'tcx>(ty: Ty<'tcx>, cx: &LateContext<'tcx>) -> bool {
     // IntoIterator is currently only implemented for array sizes <= 32 in rustc
     match ty.kind {
-        ty::Array(_, n) => {
+        ty::Array(_, n) => n
-            if let Some(val) = n.try_eval_usize(cx.tcx, cx.param_env) {
+            .try_eval_usize(cx.tcx, cx.param_env)
-                (0..=32).contains(&val)
+            .map_or(false, |val| (0..=32).contains(&val)),
-            } else {
-                false
-            }
-        },
         _ => false,
     }
 }
@@ -1899,11 +1891,7 @@ fn extract_expr_from_first_stmt<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<
         return None;
     }
     if let StmtKind::Local(ref local) = block.stmts[0].kind {
-        if let Some(expr) = local.init {
+        local.init //.map(|expr| expr)
-            Some(expr)
-        } else {
-            None
-        }
     } else {
         None
     }
@@ -2023,15 +2011,13 @@ impl<'a, 'tcx> Visitor<'tcx> for InitializeVisitor<'a, 'tcx> {
                 if let PatKind::Binding(.., ident, _) = local.pat.kind {
                     self.name = Some(ident.name);
 
-                    self.state = if let Some(ref init) = local.init {
+                    self.state = local.init.as_ref().map_or(VarState::Declared, |init| {
                         if is_integer_const(&self.cx, init, 0) {
                             VarState::Warn
                         } else {
                             VarState::Declared
                         }
-                    } else {
+                    })
-                        VarState::Declared
-                    }
                 }
             }
         }
@@ -2105,17 +2091,11 @@ fn var_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<HirId> {
 }
 
 fn is_loop(expr: &Expr<'_>) -> bool {
-    match expr.kind {
+    matches!(expr.kind, ExprKind::Loop(..))
-        ExprKind::Loop(..) => true,
-        _ => false,
-    }
 }
 
 fn is_conditional(expr: &Expr<'_>) -> bool {
-    match expr.kind {
+    matches!(expr.kind, ExprKind::Match(..))
-        ExprKind::Match(..) => true,
-        _ => false,
-    }
 }
 
 fn is_nested(cx: &LateContext<'_>, match_expr: &Expr<'_>, iter_expr: &Expr<'_>) -> bool {

clippy_lints/src/map_identity.rs

@@ -0,0 +1,126 @@
+use crate::utils::{
+    is_adjusted, is_type_diagnostic_item, match_path, match_trait_method, match_var, paths, remove_blocks,
+    span_lint_and_sugg,
+};
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{Body, Expr, ExprKind, Pat, PatKind, QPath, StmtKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for instances of `map(f)` where `f` is the identity function.
+    ///
+    /// **Why is this bad?** It can be written more concisely without the call to `map`.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// let x = [1, 2, 3];
+    /// let y: Vec<_> = x.iter().map(|x| x).map(|x| 2*x).collect();
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let x = [1, 2, 3];
+    /// let y: Vec<_> = x.iter().map(|x| 2*x).collect();
+    /// ```
+    pub MAP_IDENTITY,
+    complexity,
+    "using iterator.map(|x| x)"
+}
+
+declare_lint_pass!(MapIdentity => [MAP_IDENTITY]);
+
+impl<'tcx> LateLintPass<'tcx> for MapIdentity {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+        if expr.span.from_expansion() {
+            return;
+        }
+
+        if_chain! {
+            if let Some([caller, func]) = get_map_argument(cx, expr);
+            if is_expr_identity_function(cx, func);
+            then {
+                span_lint_and_sugg(
+                    cx,
+                    MAP_IDENTITY,
+                    expr.span.trim_start(caller.span).unwrap(),
+                    "unnecessary map of the identity function",
+                    "remove the call to `map`",
+                    String::new(),
+                    Applicability::MachineApplicable
+                )
+            }
+        }
+    }
+}
+
+/// Returns the arguments passed into map() if the expression is a method call to
+/// map(). Otherwise, returns None.
+fn get_map_argument<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<&'a [Expr<'a>]> {
+    if_chain! {
+        if let ExprKind::MethodCall(ref method, _, ref args, _) = expr.kind;
+        if args.len() == 2 && method.ident.as_str() == "map";
+        let caller_ty = cx.tables().expr_ty(&args[0]);
+        if match_trait_method(cx, expr, &paths::ITERATOR)
+            || is_type_diagnostic_item(cx, caller_ty, sym!(result_type))
+            || is_type_diagnostic_item(cx, caller_ty, sym!(option_type));
+        then {
+            Some(args)
+        } else {
+            None
+        }
+    }
+}
+
+/// Checks if an expression represents the identity function
+/// Only examines closures and `std::convert::identity`
+fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+    match expr.kind {
+        ExprKind::Closure(_, _, body_id, _, _) => is_body_identity_function(cx, cx.tcx.hir().body(body_id)),
+        ExprKind::Path(QPath::Resolved(_, ref path)) => match_path(path, &paths::STD_CONVERT_IDENTITY),
+        _ => false,
+    }
+}
+
+/// Checks if a function's body represents the identity function
+/// Looks for bodies of the form `|x| x`, `|x| return x`, `|x| { return x }` or `|x| {
+/// return x; }`
+fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
+    let params = func.params;
+    let body = remove_blocks(&func.value);
+
+    // if there's less/more than one parameter, then it is not the identity function
+    if params.len() != 1 {
+        return false;
+    }
+
+    match body.kind {
+        ExprKind::Path(QPath::Resolved(None, _)) => match_expr_param(cx, body, params[0].pat),
+        ExprKind::Ret(Some(ref ret_val)) => match_expr_param(cx, ret_val, params[0].pat),
+        ExprKind::Block(ref block, _) => {
+            if_chain! {
+                if block.stmts.len() == 1;
+                if let StmtKind::Semi(ref expr) | StmtKind::Expr(ref expr) = block.stmts[0].kind;
+                if let ExprKind::Ret(Some(ref ret_val)) = expr.kind;
+                then {
+                    match_expr_param(cx, ret_val, params[0].pat)
+                } else {
+                    false
+                }
+            }
+        },
+        _ => false,
+    }
+}
+
+/// Returns true iff an expression returns the same thing as a parameter's pattern
+fn match_expr_param(cx: &LateContext<'_>, expr: &Expr<'_>, pat: &Pat<'_>) -> bool {
+    if let PatKind::Binding(_, _, ident, _) = pat.kind {
+        match_var(expr, ident.name) && !(cx.tables().hir_owner == expr.hir_id.owner && is_adjusted(cx, expr))
+    } else {
+        false
+    }
+}

clippy_lints/src/matches.rs

@@ -13,14 +13,14 @@ use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::def::CtorKind;
 use rustc_hir::{
-    Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Local, MatchSource, Mutability, Node, Pat, PatKind,
+    Arm, BindingAnnotation, Block, BorrowKind, Expr, ExprKind, Guard, Local, MatchSource, Mutability, Node, Pat,
-    QPath, RangeEnd,
+    PatKind, QPath, RangeEnd,
 };
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::source_map::Span;
+use rustc_span::source_map::{Span, Spanned};
 use std::cmp::Ordering;
 use std::collections::Bound;
 
@@ -409,6 +409,74 @@ declare_clippy_lint! {
     "a match on a struct that binds all fields but still uses the wildcard pattern"
 }
 
+declare_clippy_lint! {
+    /// **What it does:** Lint for redundant pattern matching over `Result` or
+    /// `Option`
+    ///
+    /// **Why is this bad?** It's more concise and clear to just use the proper
+    /// utility function
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// if let Ok(_) = Ok::<i32, i32>(42) {}
+    /// if let Err(_) = Err::<i32, i32>(42) {}
+    /// if let None = None::<()> {}
+    /// if let Some(_) = Some(42) {}
+    /// match Ok::<i32, i32>(42) {
+    ///     Ok(_) => true,
+    ///     Err(_) => false,
+    /// };
+    /// ```
+    ///
+    /// The more idiomatic use would be:
+    ///
+    /// ```rust
+    /// if Ok::<i32, i32>(42).is_ok() {}
+    /// if Err::<i32, i32>(42).is_err() {}
+    /// if None::<()>.is_none() {}
+    /// if Some(42).is_some() {}
+    /// Ok::<i32, i32>(42).is_ok();
+    /// ```
+    pub REDUNDANT_PATTERN_MATCHING,
+    style,
+    "use the proper utility function avoiding an `if let`"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for `match`  or `if let` expressions producing a
+    /// `bool` that could be written using `matches!`
+    ///
+    /// **Why is this bad?** Readability and needless complexity.
+    ///
+    /// **Known problems:** None
+    ///
+    /// **Example:**
+    /// ```rust
+    /// let x = Some(5);
+    ///
+    /// // Bad
+    /// let a = match x {
+    ///     Some(0) => true,
+    ///     _ => false,
+    /// };
+    ///
+    /// let a = if let Some(0) = x {
+    ///     true
+    /// } else {
+    ///     false
+    /// };
+    ///
+    /// // Good
+    /// let a = matches!(x, Some(0));
+    /// ```
+    pub MATCH_LIKE_MATCHES_MACRO,
+    style,
+    "a match that could be written with the matches! macro"
+}
+
 #[derive(Default)]
 pub struct Matches {
     infallible_destructuring_match_linted: bool,
@@ -427,7 +495,9 @@ impl_lint_pass!(Matches => [
     WILDCARD_IN_OR_PATTERNS,
     MATCH_SINGLE_BINDING,
     INFALLIBLE_DESTRUCTURING_MATCH,
-    REST_PAT_IN_FULLY_BOUND_STRUCTS
+    REST_PAT_IN_FULLY_BOUND_STRUCTS,
+    REDUNDANT_PATTERN_MATCHING,
+    MATCH_LIKE_MATCHES_MACRO
 ]);
 
 impl<'tcx> LateLintPass<'tcx> for Matches {
@@ -435,6 +505,10 @@ impl<'tcx> LateLintPass<'tcx> for Matches {
         if in_external_macro(cx.sess(), expr.span) {
             return;
         }
+
+        redundant_pattern_match::check(cx, expr);
+        check_match_like_matches(cx, expr);
+
         if let ExprKind::Match(ref ex, ref arms, MatchSource::Normal) = expr.kind {
             check_single_match(cx, ex, arms, expr);
             check_match_bool(cx, ex, arms, expr);
@@ -530,16 +604,22 @@ fn check_single_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], exp
             // the lint noisy in unnecessary situations
             return;
         }
-        let els = remove_blocks(&arms[1].body);
+        let els = arms[1].body;
-        let els = if is_unit_expr(els) {
+        let els = if is_unit_expr(remove_blocks(els)) {
             None
-        } else if let ExprKind::Block(_, _) = els.kind {
+        } else if let ExprKind::Block(Block { stmts, expr: block_expr, .. }, _) = els.kind {
-            // matches with blocks that contain statements are prettier as `if let + else`
+            if stmts.len() == 1 && block_expr.is_none() || stmts.is_empty() && block_expr.is_some() {
-            Some(els)
+                // single statement/expr "else" block, don't lint
+                return;
+            } else {
+                // block with 2+ statements or 1 expr and 1+ statement
+                Some(els)
+            }
         } else {
-            // allow match arms with just expressions
+            // not a block, don't lint
-            return;
+            return; 
         };
+
         let ty = cx.tables().expr_ty(ex);
         if ty.kind != ty::Bool || is_allowed(cx, MATCH_BOOL, ex.hir_id) {
             check_single_match_single_pattern(cx, ex, arms, expr, els);
@@ -802,13 +882,8 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
                     // Some simple checks for exhaustive patterns.
                     // There is a room for improvements to detect more cases,
                     // but it can be more expensive to do so.
-                    let is_pattern_exhaustive = |pat: &&Pat<'_>| {
+                    let is_pattern_exhaustive =
-                        if let PatKind::Wild | PatKind::Binding(.., None) = pat.kind {
+                        |pat: &&Pat<'_>| matches!(pat.kind, PatKind::Wild | PatKind::Binding(.., None));
-                            true
-                        } else {
-                            false
-                        }
-                    };
                     if patterns.iter().all(is_pattern_exhaustive) {
                         missing_variants.retain(|e| e.ctor_def_id != Some(p.res.def_id()));
                     }
@@ -989,6 +1064,79 @@ fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
     }
 }
 
+/// Lint a `match` or `if let .. { .. } else { .. }` expr that could be replaced by `matches!`
+fn check_match_like_matches<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+    if let ExprKind::Match(ex, arms, ref match_source) = &expr.kind {
+        match match_source {
+            MatchSource::Normal => find_matches_sugg(cx, ex, arms, expr, false),
+            MatchSource::IfLetDesugar { .. } => find_matches_sugg(cx, ex, arms, expr, true),
+            _ => return,
+        }
+    }
+}
+
+/// Lint a `match` or desugared `if let` for replacement by `matches!`
+fn find_matches_sugg(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>, desugared: bool) {
+    if_chain! {
+        if arms.len() == 2;
+        if cx.tables().expr_ty(expr).is_bool();
+        if is_wild(&arms[1].pat);
+        if let Some(first) = find_bool_lit(&arms[0].body.kind, desugared);
+        if let Some(second) = find_bool_lit(&arms[1].body.kind, desugared);
+        if first != second;
+        then {
+            let mut applicability = Applicability::MachineApplicable;
+
+            let pat_and_guard = if let Some(Guard::If(g)) = arms[0].guard {
+                format!("{} if {}", snippet_with_applicability(cx, arms[0].pat.span, "..", &mut applicability), snippet_with_applicability(cx, g.span, "..", &mut applicability))
+            } else {
+                format!("{}", snippet_with_applicability(cx, arms[0].pat.span, "..", &mut applicability))
+            };
+            span_lint_and_sugg(
+                cx,
+                MATCH_LIKE_MATCHES_MACRO,
+                expr.span,
+                &format!("{} expression looks like `matches!` macro", if desugared { "if let .. else" } else { "match" }),
+                "try this",
+                format!(
+                    "{}matches!({}, {})",
+                    if first { "" } else { "!" },
+                    snippet_with_applicability(cx, ex.span, "..", &mut applicability),
+                    pat_and_guard,
+                ),
+                applicability,
+            )
+        }
+    }
+}
+
+/// Extract a `bool` or `{ bool }`
+fn find_bool_lit(ex: &ExprKind<'_>, desugared: bool) -> Option<bool> {
+    match ex {
+        ExprKind::Lit(Spanned {
+            node: LitKind::Bool(b), ..
+        }) => Some(*b),
+        ExprKind::Block(
+            rustc_hir::Block {
+                stmts: &[],
+                expr: Some(exp),
+                ..
+            },
+            _,
+        ) if desugared => {
+            if let ExprKind::Lit(Spanned {
+                node: LitKind::Bool(b), ..
+            }) = exp.kind
+            {
+                Some(b)
+            } else {
+                None
+            }
+        },
+        _ => None,
+    }
+}
+
 fn check_match_single_binding<'a>(cx: &LateContext<'a>, ex: &Expr<'a>, arms: &[Arm<'_>], expr: &Expr<'_>) {
     if in_macro(expr.span) || arms.len() != 1 || is_refutable(cx, arms[0].pat) {
         return;
@@ -1179,10 +1327,7 @@ fn is_unit_expr(expr: &Expr<'_>) -> bool {
 
 // Checks if arm has the form `None => None`
 fn is_none_arm(arm: &Arm<'_>) -> bool {
-    match arm.pat.kind {
+    matches!(arm.pat.kind, PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE))
-        PatKind::Path(ref path) if match_qpath(path, &paths::OPTION_NONE) => true,
-        _ => false,
-    }
 }
 
 // Checks if arm has the form `Some(ref v) => Some(v)` (checks for `ref` and `ref mut`)
@@ -1293,6 +1438,229 @@ where
     None
 }
 
+mod redundant_pattern_match {
+    use super::REDUNDANT_PATTERN_MATCHING;
+    use crate::utils::{in_constant, match_qpath, match_trait_method, paths, snippet, span_lint_and_then};
+    use if_chain::if_chain;
+    use rustc_ast::ast::LitKind;
+    use rustc_errors::Applicability;
+    use rustc_hir::{Arm, Expr, ExprKind, HirId, MatchSource, PatKind, QPath};
+    use rustc_lint::LateContext;
+    use rustc_middle::ty;
+    use rustc_mir::const_eval::is_const_fn;
+    use rustc_span::source_map::Symbol;
+
+    pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if let ExprKind::Match(op, arms, ref match_source) = &expr.kind {
+            match match_source {
+                MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
+                MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms, "if"),
+                MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, arms, "while"),
+                _ => {},
+            }
+        }
+    }
+
+    fn find_sugg_for_if_let<'tcx>(
+        cx: &LateContext<'tcx>,
+        expr: &'tcx Expr<'_>,
+        op: &Expr<'_>,
+        arms: &[Arm<'_>],
+        keyword: &'static str,
+    ) {
+        fn find_suggestion(cx: &LateContext<'_>, hir_id: HirId, path: &QPath<'_>) -> Option<&'static str> {
+            if match_qpath(path, &paths::RESULT_OK) && can_suggest(cx, hir_id, sym!(result_type), "is_ok") {
+                return Some("is_ok()");
+            }
+            if match_qpath(path, &paths::RESULT_ERR) && can_suggest(cx, hir_id, sym!(result_type), "is_err") {
+                return Some("is_err()");
+            }
+            if match_qpath(path, &paths::OPTION_SOME) && can_suggest(cx, hir_id, sym!(option_type), "is_some") {
+                return Some("is_some()");
+            }
+            if match_qpath(path, &paths::OPTION_NONE) && can_suggest(cx, hir_id, sym!(option_type), "is_none") {
+                return Some("is_none()");
+            }
+            None
+        }
+
+        let hir_id = expr.hir_id;
+        let good_method = match arms[0].pat.kind {
+            PatKind::TupleStruct(ref path, ref patterns, _) if patterns.len() == 1 => {
+                if let PatKind::Wild = patterns[0].kind {
+                    find_suggestion(cx, hir_id, path)
+                } else {
+                    None
+                }
+            },
+            PatKind::Path(ref path) => find_suggestion(cx, hir_id, path),
+            _ => None,
+        };
+        let good_method = match good_method {
+            Some(method) => method,
+            None => return,
+        };
+
+        // check that `while_let_on_iterator` lint does not trigger
+        if_chain! {
+            if keyword == "while";
+            if let ExprKind::MethodCall(method_path, _, _, _) = op.kind;
+            if method_path.ident.name == sym!(next);
+            if match_trait_method(cx, op, &paths::ITERATOR);
+            then {
+                return;
+            }
+        }
+
+        span_lint_and_then(
+            cx,
+            REDUNDANT_PATTERN_MATCHING,
+            arms[0].pat.span,
+            &format!("redundant pattern matching, consider using `{}`", good_method),
+            |diag| {
+                // while let ... = ... { ... }
+                // ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+                let expr_span = expr.span;
+
+                // while let ... = ... { ... }
+                //                 ^^^
+                let op_span = op.span.source_callsite();
+
+                // while let ... = ... { ... }
+                // ^^^^^^^^^^^^^^^^^^^
+                let span = expr_span.until(op_span.shrink_to_hi());
+                diag.span_suggestion(
+                    span,
+                    "try this",
+                    format!("{} {}.{}", keyword, snippet(cx, op_span, "_"), good_method),
+                    Applicability::MachineApplicable, // snippet
+                );
+            },
+        );
+    }
+
+    fn find_sugg_for_match<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, op: &Expr<'_>, arms: &[Arm<'_>]) {
+        if arms.len() == 2 {
+            let node_pair = (&arms[0].pat.kind, &arms[1].pat.kind);
+
+            let hir_id = expr.hir_id;
+            let found_good_method = match node_pair {
+                (
+                    PatKind::TupleStruct(ref path_left, ref patterns_left, _),
+                    PatKind::TupleStruct(ref path_right, ref patterns_right, _),
+                ) if patterns_left.len() == 1 && patterns_right.len() == 1 => {
+                    if let (PatKind::Wild, PatKind::Wild) = (&patterns_left[0].kind, &patterns_right[0].kind) {
+                        find_good_method_for_match(
+                            arms,
+                            path_left,
+                            path_right,
+                            &paths::RESULT_OK,
+                            &paths::RESULT_ERR,
+                            "is_ok()",
+                            "is_err()",
+                            || can_suggest(cx, hir_id, sym!(result_type), "is_ok"),
+                            || can_suggest(cx, hir_id, sym!(result_type), "is_err"),
+                        )
+                    } else {
+                        None
+                    }
+                },
+                (PatKind::TupleStruct(ref path_left, ref patterns, _), PatKind::Path(ref path_right))
+                | (PatKind::Path(ref path_left), PatKind::TupleStruct(ref path_right, ref patterns, _))
+                    if patterns.len() == 1 =>
+                {
+                    if let PatKind::Wild = patterns[0].kind {
+                        find_good_method_for_match(
+                            arms,
+                            path_left,
+                            path_right,
+                            &paths::OPTION_SOME,
+                            &paths::OPTION_NONE,
+                            "is_some()",
+                            "is_none()",
+                            || can_suggest(cx, hir_id, sym!(option_type), "is_some"),
+                            || can_suggest(cx, hir_id, sym!(option_type), "is_none"),
+                        )
+                    } else {
+                        None
+                    }
+                },
+                _ => None,
+            };
+
+            if let Some(good_method) = found_good_method {
+                span_lint_and_then(
+                    cx,
+                    REDUNDANT_PATTERN_MATCHING,
+                    expr.span,
+                    &format!("redundant pattern matching, consider using `{}`", good_method),
+                    |diag| {
+                        let span = expr.span.to(op.span);
+                        diag.span_suggestion(
+                            span,
+                            "try this",
+                            format!("{}.{}", snippet(cx, op.span, "_"), good_method),
+                            Applicability::MaybeIncorrect, // snippet
+                        );
+                    },
+                );
+            }
+        }
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn find_good_method_for_match<'a>(
+        arms: &[Arm<'_>],
+        path_left: &QPath<'_>,
+        path_right: &QPath<'_>,
+        expected_left: &[&str],
+        expected_right: &[&str],
+        should_be_left: &'a str,
+        should_be_right: &'a str,
+        can_suggest_left: impl Fn() -> bool,
+        can_suggest_right: impl Fn() -> bool,
+    ) -> Option<&'a str> {
+        let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
+            (&(*arms[0].body).kind, &(*arms[1].body).kind)
+        } else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
+            (&(*arms[1].body).kind, &(*arms[0].body).kind)
+        } else {
+            return None;
+        };
+
+        match body_node_pair {
+            (ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => match (&lit_left.node, &lit_right.node) {
+                (LitKind::Bool(true), LitKind::Bool(false)) if can_suggest_left() => Some(should_be_left),
+                (LitKind::Bool(false), LitKind::Bool(true)) if can_suggest_right() => Some(should_be_right),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
+
+    fn can_suggest(cx: &LateContext<'_>, hir_id: HirId, diag_item: Symbol, name: &str) -> bool {
+        if !in_constant(cx, hir_id) {
+            return true;
+        }
+
+        // Avoid suggesting calls to non-`const fn`s in const contexts, see #5697.
+        cx.tcx
+            .get_diagnostic_item(diag_item)
+            .and_then(|def_id| {
+                cx.tcx.inherent_impls(def_id).iter().find_map(|imp| {
+                    cx.tcx
+                        .associated_items(*imp)
+                        .in_definition_order()
+                        .find_map(|item| match item.kind {
+                            ty::AssocKind::Fn if item.ident.name.as_str() == name => Some(item.def_id),
+                            _ => None,
+                        })
+                })
+            })
+            .map_or(false, |def_id| is_const_fn(cx.tcx, def_id))
+    }
+}
+
 #[test]
 fn test_overlapping() {
     use rustc_span::source_map::DUMMY_SP;

clippy_lints/src/methods/mod.rs

@@ -1844,10 +1844,10 @@ fn lint_expect_fun_call(
                         ty::Ref(ty::ReStatic, ..)
                     )
                 }),
-            hir::ExprKind::Path(ref p) => match cx.qpath_res(p, arg.hir_id) {
+            hir::ExprKind::Path(ref p) => matches!(
-                hir::def::Res::Def(hir::def::DefKind::Const | hir::def::DefKind::Static, _) => true,
+                cx.qpath_res(p, arg.hir_id),
-                _ => false,
+                hir::def::Res::Def(hir::def::DefKind::Const | hir::def::DefKind::Static, _)
-            },
+            ),
             _ => false,
         }
     }
@@ -2028,13 +2028,7 @@ fn lint_clone_on_copy(cx: &LateContext<'_>, expr: &hir::Expr<'_>, arg: &hir::Exp
                     .tables()
                     .expr_adjustments(arg)
                     .iter()
-                    .filter(|adj| {
+                    .filter(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(_)))
-                        if let ty::adjustment::Adjust::Deref(_) = adj.kind {
-                            true
-                        } else {
-                            false
-                        }
-                    })
                     .count();
                 let derefs: String = iter::repeat('*').take(deref_count).collect();
                 snip = Some(("try dereferencing it", format!("{}{}", derefs, snippet)));
@@ -2044,7 +2038,7 @@ fn lint_clone_on_copy(cx: &LateContext<'_>, expr: &hir::Expr<'_>, arg: &hir::Exp
         }
         span_lint_and_then(cx, CLONE_ON_COPY, expr.span, "using `clone` on a `Copy` type", |diag| {
             if let Some((text, snip)) = snip {
-                diag.span_suggestion(expr.span, text, snip, Applicability::Unspecified);
+                diag.span_suggestion(expr.span, text, snip, Applicability::MachineApplicable);
             }
         });
     }
@@ -2460,13 +2454,9 @@ fn derefs_to_slice<'tcx>(
             ty::Slice(_) => true,
             ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
             ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym!(vec_type)),
-            ty::Array(_, size) => {
+            ty::Array(_, size) => size
-                if let Some(size) = size.try_eval_usize(cx.tcx, cx.param_env) {
+                .try_eval_usize(cx.tcx, cx.param_env)
-                    size < 32
+                .map_or(false, |size| size < 32),
-                } else {
-                    false
-                }
-            },
             ty::Ref(_, inner, _) => may_slice(cx, inner),
             _ => false,
         }

clippy_lints/src/methods/unnecessary_filter_map.rs

@@ -77,13 +77,10 @@ fn check_expression<'tcx>(cx: &LateContext<'tcx>, arg_id: hir::HirId, expr: &'tc
             }
             (true, true)
         },
-        hir::ExprKind::Block(ref block, _) => {
+        hir::ExprKind::Block(ref block, _) => block
-            if let Some(expr) = &block.expr {
+            .expr
-                check_expression(cx, arg_id, &expr)
+            .as_ref()
-            } else {
+            .map_or((false, false), |expr| check_expression(cx, arg_id, &expr)),
-                (false, false)
-            }
-        },
         hir::ExprKind::Match(_, arms, _) => {
             let mut found_mapping = false;
             let mut found_filtering = false;

clippy_lints/src/minmax.rs

@@ -53,7 +53,7 @@ impl<'tcx> LateLintPass<'tcx> for MinMaxPass {
     }
 }
 
-#[derive(PartialEq, Eq, Debug)]
+#[derive(PartialEq, Eq, Debug, Clone, Copy)]
 enum MinMax {
     Min,
     Max,
@@ -86,16 +86,15 @@ fn fetch_const<'a>(cx: &LateContext<'_>, args: &'a [Expr<'a>], m: MinMax) -> Opt
     if args.len() != 2 {
         return None;
     }
-    if let Some(c) = constant_simple(cx, cx.tables(), &args[0]) {
+    constant_simple(cx, cx.tables(), &args[0]).map_or_else(
-        if constant_simple(cx, cx.tables(), &args[1]).is_none() {
+        || constant_simple(cx, cx.tables(), &args[1]).map(|c| (m, c, &args[0])),
-            // otherwise ignore
+        |c| {
-            Some((m, c, &args[1]))
+            if constant_simple(cx, cx.tables(), &args[1]).is_none() {
-        } else {
+                // otherwise ignore
-            None
+                Some((m, c, &args[1]))
-        }
+            } else {
-    } else if let Some(c) = constant_simple(cx, cx.tables(), &args[1]) {
+                None
-        Some((m, c, &args[0]))
+            }
-    } else {
+        },
-        None
+    )
-    }
 }

clippy_lints/src/misc.rs

@@ -3,11 +3,11 @@ use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{
-    def, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, HirId, Mutability, PatKind, Stmt, StmtKind, Ty,
+    self as hir, def, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, HirId, Mutability, PatKind, Stmt,
-    TyKind, UnOp,
+    StmtKind, TyKind, UnOp,
 };
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty;
+use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::{ExpnKind, Span};
@@ -371,8 +371,8 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
                 if op.is_comparison() {
                     check_nan(cx, left, expr);
                     check_nan(cx, right, expr);
-                    check_to_owned(cx, left, right);
+                    check_to_owned(cx, left, right, true);
-                    check_to_owned(cx, right, left);
+                    check_to_owned(cx, right, left, false);
                 }
                 if (op == BinOpKind::Eq || op == BinOpKind::Ne) && (is_float(cx, left) || is_float(cx, right)) {
                     if is_allowed(cx, left) || is_allowed(cx, right) {
@@ -570,11 +570,30 @@ fn is_array(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     matches!(&walk_ptrs_ty(cx.tables().expr_ty(expr)).kind, ty::Array(_, _))
 }
 
-fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>) {
+fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>, left: bool) {
+    #[derive(Default)]
+    struct EqImpl {
+        ty_eq_other: bool,
+        other_eq_ty: bool,
+    }
+
+    impl EqImpl {
+        fn is_implemented(&self) -> bool {
+            self.ty_eq_other || self.other_eq_ty
+        }
+    }
+
+    fn symmetric_partial_eq<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, other: Ty<'tcx>) -> Option<EqImpl> {
+        cx.tcx.lang_items().eq_trait().map(|def_id| EqImpl {
+            ty_eq_other: implements_trait(cx, ty, def_id, &[other.into()]),
+            other_eq_ty: implements_trait(cx, other, def_id, &[ty.into()]),
+        })
+    }
+
     let (arg_ty, snip) = match expr.kind {
         ExprKind::MethodCall(.., ref args, _) if args.len() == 1 => {
             if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
-                (cx.tables().expr_ty_adjusted(&args[0]), snippet(cx, args[0].span, ".."))
+                (cx.tables().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
             } else {
                 return;
             }
@@ -582,7 +601,7 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>) {
         ExprKind::Call(ref path, ref v) if v.len() == 1 => {
             if let ExprKind::Path(ref path) = path.kind {
                 if match_qpath(path, &["String", "from_str"]) || match_qpath(path, &["String", "from"]) {
-                    (cx.tables().expr_ty_adjusted(&v[0]), snippet(cx, v[0].span, ".."))
+                    (cx.tables().expr_ty(&v[0]), snippet(cx, v[0].span, ".."))
                 } else {
                     return;
                 }
@@ -593,28 +612,19 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>) {
         _ => return,
     };
 
-    let other_ty = cx.tables().expr_ty_adjusted(other);
+    let other_ty = cx.tables().expr_ty(other);
-    let partial_eq_trait_id = match cx.tcx.lang_items().eq_trait() {
-        Some(id) => id,
-        None => return,
-    };
 
-    let deref_arg_impl_partial_eq_other = arg_ty.builtin_deref(true).map_or(false, |tam| {
+    let without_deref = symmetric_partial_eq(cx, arg_ty, other_ty).unwrap_or_default();
-        implements_trait(cx, tam.ty, partial_eq_trait_id, &[other_ty.into()])
+    let with_deref = arg_ty
-    });
+        .builtin_deref(true)
-    let arg_impl_partial_eq_deref_other = other_ty.builtin_deref(true).map_or(false, |tam| {
+        .and_then(|tam| symmetric_partial_eq(cx, tam.ty, other_ty))
-        implements_trait(cx, arg_ty, partial_eq_trait_id, &[tam.ty.into()])
+        .unwrap_or_default();
-    });
-    let arg_impl_partial_eq_other = implements_trait(cx, arg_ty, partial_eq_trait_id, &[other_ty.into()]);
 
-    if !deref_arg_impl_partial_eq_other && !arg_impl_partial_eq_deref_other && !arg_impl_partial_eq_other {
+    if !with_deref.is_implemented() && !without_deref.is_implemented() {
         return;
     }
 
-    let other_gets_derefed = match other.kind {
+    let other_gets_derefed = matches!(other.kind, ExprKind::Unary(UnOp::UnDeref, _));
-        ExprKind::Unary(UnOp::UnDeref, _) => true,
-        _ => false,
-    };
 
     let lint_span = if other_gets_derefed {
         expr.span.to(other.span)
@@ -634,18 +644,34 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>) {
                 return;
             }
 
-            let try_hint = if deref_arg_impl_partial_eq_other {
+            let expr_snip;
-                // suggest deref on the left
+            let eq_impl;
-                format!("*{}", snip)
+            if with_deref.is_implemented() {
+                expr_snip = format!("*{}", snip);
+                eq_impl = with_deref;
             } else {
-                // suggest dropping the to_owned on the left
+                expr_snip = snip.to_string();
-                snip.to_string()
+                eq_impl = without_deref;
             };
 
+            let span;
+            let hint;
+            if (eq_impl.ty_eq_other && left) || (eq_impl.other_eq_ty && !left) {
+                span = expr.span;
+                hint = expr_snip;
+            } else {
+                span = expr.span.to(other.span);
+                if eq_impl.ty_eq_other {
+                    hint = format!("{} == {}", expr_snip, snippet(cx, other.span, ".."));
+                } else {
+                    hint = format!("{} == {}", snippet(cx, other.span, ".."), expr_snip);
+                }
+            }
+
             diag.span_suggestion(
-                lint_span,
+                span,
                 "try",
-                try_hint,
+                hint,
                 Applicability::MachineApplicable, // snippet
             );
         },
@@ -656,16 +682,10 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>) {
 /// `unused_variables`'s idea
 /// of what it means for an expression to be "used".
 fn is_used(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
-    if let Some(parent) = get_parent_expr(cx, expr) {
+    get_parent_expr(cx, expr).map_or(true, |parent| match parent.kind {
-        match parent.kind {
+        ExprKind::Assign(_, ref rhs, _) | ExprKind::AssignOp(_, _, ref rhs) => SpanlessEq::new(cx).eq_expr(rhs, expr),
-            ExprKind::Assign(_, ref rhs, _) | ExprKind::AssignOp(_, _, ref rhs) => {
+        _ => is_used(cx, parent),
-                SpanlessEq::new(cx).eq_expr(rhs, expr)
+    })
-            },
-            _ => is_used(cx, parent),
-        }
-    } else {
-        true
-    }
 }
 
 /// Tests whether an expression is in a macro expansion (e.g., something
@@ -674,12 +694,7 @@ fn in_attributes_expansion(expr: &Expr<'_>) -> bool {
     use rustc_span::hygiene::MacroKind;
     if expr.span.from_expansion() {
         let data = expr.span.ctxt().outer_expn_data();
-
+        matches!(data.kind, ExpnKind::Macro(MacroKind::Attr, _))
-        if let ExpnKind::Macro(MacroKind::Attr, _) = data.kind {
-            true
-        } else {
-            false
-        }
     } else {
         false
     }
@@ -694,7 +709,7 @@ fn non_macro_local(cx: &LateContext<'_>, res: def::Res) -> bool {
     }
 }
 
-fn check_cast(cx: &LateContext<'_>, span: Span, e: &Expr<'_>, ty: &Ty<'_>) {
+fn check_cast(cx: &LateContext<'_>, span: Span, e: &Expr<'_>, ty: &hir::Ty<'_>) {
     if_chain! {
         if let TyKind::Ptr(ref mut_ty) = ty.kind;
         if let ExprKind::Lit(ref lit) = e.kind;

clippy_lints/src/misc_early.rs

@@ -641,28 +641,22 @@ fn check_unneeded_wildcard_pattern(cx: &EarlyContext<'_>, pat: &Pat) {
             );
         }
 
-        #[allow(clippy::trivially_copy_pass_by_ref)]
-        fn is_wild<P: std::ops::Deref<Target = Pat>>(pat: &&P) -> bool {
-            if let PatKind::Wild = pat.kind {
-                true
-            } else {
-                false
-            }
-        }
-
         if let Some(rest_index) = patterns.iter().position(|pat| pat.is_rest()) {
             if let Some((left_index, left_pat)) = patterns[..rest_index]
                 .iter()
                 .rev()
-                .take_while(is_wild)
+                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
                 .enumerate()
                 .last()
             {
                 span_lint(cx, left_pat.span.until(patterns[rest_index].span), left_index == 0);
             }
 
-            if let Some((right_index, right_pat)) =
+            if let Some((right_index, right_pat)) = patterns[rest_index + 1..]
-                patterns[rest_index + 1..].iter().take_while(is_wild).enumerate().last()
+                .iter()
+                .take_while(|pat| matches!(pat.kind, PatKind::Wild))
+                .enumerate()
+                .last()
             {
                 span_lint(
                     cx,

clippy_lints/src/missing_inline.rs

@@ -71,10 +71,11 @@ fn check_missing_inline_attrs(cx: &LateContext<'_>, attrs: &[ast::Attribute], sp
 fn is_executable(cx: &LateContext<'_>) -> bool {
     use rustc_session::config::CrateType;
 
-    cx.tcx.sess.crate_types().iter().any(|t: &CrateType| match t {
+    cx.tcx
-        CrateType::Executable => true,
+        .sess
-        _ => false,
+        .crate_types()
-    })
+        .iter()
+        .any(|t: &CrateType| matches!(t, CrateType::Executable))
 }
 
 declare_lint_pass!(MissingInline => [MISSING_INLINE_IN_PUBLIC_ITEMS]);

clippy_lints/src/new_without_default.rs

@@ -80,10 +80,12 @@ impl<'tcx> LateLintPass<'tcx> for NewWithoutDefault {
                             // can't be implemented for unsafe new
                             return;
                         }
-                        if impl_item.generics.params.iter().any(|gen| match gen.kind {
+                        if impl_item
-                            hir::GenericParamKind::Type { .. } => true,
+                            .generics
-                            _ => false,
+                            .params
-                        }) {
+                            .iter()
+                            .any(|gen| matches!(gen.kind, hir::GenericParamKind::Type { .. }))
+                        {
                             // when the result of `new()` depends on a type parameter we should not require
                             // an
                             // impl of `Default`

clippy_lints/src/non_copy_const.rs

@@ -238,10 +238,10 @@ impl<'tcx> LateLintPass<'tcx> for NonCopyConst {
 
             let ty = if needs_check_adjustment {
                 let adjustments = cx.tables().expr_adjustments(dereferenced_expr);
-                if let Some(i) = adjustments.iter().position(|adj| match adj.kind {
+                if let Some(i) = adjustments
-                    Adjust::Borrow(_) | Adjust::Deref(_) => true,
+                    .iter()
-                    _ => false,
+                    .position(|adj| matches!(adj.kind, Adjust::Borrow(_) | Adjust::Deref(_)))
-                }) {
+                {
                     if i == 0 {
                         cx.tables().expr_ty(dereferenced_expr)
                     } else {

clippy_lints/src/option_if_let_else.rs

@@ -0,0 +1,267 @@
+use crate::utils;
+use crate::utils::sugg::Sugg;
+use crate::utils::{match_type, paths, span_lint_and_sugg};
+use if_chain::if_chain;
+
+use rustc_errors::Applicability;
+use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
+use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, PatKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::hir::map::Map;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:**
+    /// Lints usage of  `if let Some(v) = ... { y } else { x }` which is more
+    /// idiomatically done with `Option::map_or` (if the else bit is a simple
+    /// expression) or `Option::map_or_else` (if the else bit is a longer
+    /// block).
+    ///
+    /// **Why is this bad?**
+    /// Using the dedicated functions of the Option type is clearer and
+    /// more concise than an if let expression.
+    ///
+    /// **Known problems:**
+    /// This lint uses whether the block is just an expression or if it has
+    /// more statements to decide whether to use `Option::map_or` or
+    /// `Option::map_or_else`. If you have a single expression which calls
+    /// an expensive function, then it would be more efficient to use
+    /// `Option::map_or_else`, but this lint would suggest `Option::map_or`.
+    ///
+    /// Also, this lint uses a deliberately conservative metric for checking
+    /// if the inside of either body contains breaks or continues which will
+    /// cause it to not suggest a fix if either block contains a loop with
+    /// continues or breaks contained within the loop.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// # let optional: Option<u32> = Some(0);
+    /// # fn do_complicated_function() -> u32 { 5 };
+    /// let _ = if let Some(foo) = optional {
+    ///     foo
+    /// } else {
+    ///     5
+    /// };
+    /// let _ = if let Some(foo) = optional {
+    ///     foo
+    /// } else {
+    ///     let y = do_complicated_function();
+    ///     y*y
+    /// };
+    /// ```
+    ///
+    /// should be
+    ///
+    /// ```rust
+    /// # let optional: Option<u32> = Some(0);
+    /// # fn do_complicated_function() -> u32 { 5 };
+    /// let _ = optional.map_or(5, |foo| foo);
+    /// let _ = optional.map_or_else(||{
+    ///     let y = do_complicated_function();
+    ///     y*y
+    /// }, |foo| foo);
+    /// ```
+    pub OPTION_IF_LET_ELSE,
+    pedantic,
+    "reimplementation of Option::map_or"
+}
+
+declare_lint_pass!(OptionIfLetElse => [OPTION_IF_LET_ELSE]);
+
+/// Returns true iff the given expression is the result of calling `Result::ok`
+fn is_result_ok(cx: &LateContext<'_>, expr: &'_ Expr<'_>) -> bool {
+    if let ExprKind::MethodCall(ref path, _, &[ref receiver], _) = &expr.kind {
+        path.ident.name.to_ident_string() == "ok" && match_type(cx, &cx.tables().expr_ty(&receiver), &paths::RESULT)
+    } else {
+        false
+    }
+}
+
+/// A struct containing information about occurences of the
+/// `if let Some(..) = .. else` construct that this lint detects.
+struct OptionIfLetElseOccurence {
+    option: String,
+    method_sugg: String,
+    some_expr: String,
+    none_expr: String,
+    wrap_braces: bool,
+}
+
+struct ReturnBreakContinueMacroVisitor {
+    seen_return_break_continue: bool,
+}
+impl ReturnBreakContinueMacroVisitor {
+    fn new() -> ReturnBreakContinueMacroVisitor {
+        ReturnBreakContinueMacroVisitor {
+            seen_return_break_continue: false,
+        }
+    }
+}
+impl<'tcx> Visitor<'tcx> for ReturnBreakContinueMacroVisitor {
+    type Map = Map<'tcx>;
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::None
+    }
+
+    fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
+        if self.seen_return_break_continue {
+            // No need to look farther if we've already seen one of them
+            return;
+        }
+        match &ex.kind {
+            ExprKind::Ret(..) | ExprKind::Break(..) | ExprKind::Continue(..) => {
+                self.seen_return_break_continue = true;
+            },
+            // Something special could be done here to handle while or for loop
+            // desugaring, as this will detect a break if there's a while loop
+            // or a for loop inside the expression.
+            _ => {
+                if utils::in_macro(ex.span) {
+                    self.seen_return_break_continue = true;
+                } else {
+                    rustc_hir::intravisit::walk_expr(self, ex);
+                }
+            },
+        }
+    }
+}
+
+fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
+    let mut recursive_visitor = ReturnBreakContinueMacroVisitor::new();
+    recursive_visitor.visit_expr(expression);
+    recursive_visitor.seen_return_break_continue
+}
+
+/// Extracts the body of a given arm. If the arm contains only an expression,
+/// then it returns the expression. Otherwise, it returns the entire block
+fn extract_body_from_arm<'a>(arm: &'a Arm<'a>) -> Option<&'a Expr<'a>> {
+    if let ExprKind::Block(
+        Block {
+            stmts: statements,
+            expr: Some(expr),
+            ..
+        },
+        _,
+    ) = &arm.body.kind
+    {
+        if let [] = statements {
+            Some(&expr)
+        } else {
+            Some(&arm.body)
+        }
+    } else {
+        None
+    }
+}
+
+/// If this is the else body of an if/else expression, then we need to wrap
+/// it in curcly braces. Otherwise, we don't.
+fn should_wrap_in_braces(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+    utils::get_enclosing_block(cx, expr.hir_id).map_or(false, |parent| {
+        if let Some(Expr {
+            kind:
+                ExprKind::Match(
+                    _,
+                    arms,
+                    MatchSource::IfDesugar {
+                        contains_else_clause: true,
+                    }
+                    | MatchSource::IfLetDesugar {
+                        contains_else_clause: true,
+                    },
+                ),
+            ..
+        }) = parent.expr
+        {
+            expr.hir_id == arms[1].body.hir_id
+        } else {
+            false
+        }
+    })
+}
+
+fn format_option_in_sugg(cx: &LateContext<'_>, cond_expr: &Expr<'_>, as_ref: bool, as_mut: bool) -> String {
+    format!(
+        "{}{}",
+        Sugg::hir(cx, cond_expr, "..").maybe_par(),
+        if as_mut {
+            ".as_mut()"
+        } else if as_ref {
+            ".as_ref()"
+        } else {
+            ""
+        }
+    )
+}
+
+/// If this expression is the option if let/else construct we're detecting, then
+/// this function returns an `OptionIfLetElseOccurence` struct with details if
+/// this construct is found, or None if this construct is not found.
+fn detect_option_if_let_else(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<OptionIfLetElseOccurence> {
+    if_chain! {
+        if !utils::in_macro(expr.span); // Don't lint macros, because it behaves weirdly
+        if let ExprKind::Match(cond_expr, arms, MatchSource::IfLetDesugar{contains_else_clause: true}) = &expr.kind;
+        if arms.len() == 2;
+        if !is_result_ok(cx, cond_expr); // Don't lint on Result::ok because a different lint does it already
+        if let PatKind::TupleStruct(struct_qpath, &[inner_pat], _) = &arms[0].pat.kind;
+        if utils::match_qpath(struct_qpath, &paths::OPTION_SOME);
+        if let PatKind::Binding(bind_annotation, _, id, _) = &inner_pat.kind;
+        if !contains_return_break_continue_macro(arms[0].body);
+        if !contains_return_break_continue_macro(arms[1].body);
+        then {
+            let capture_mut = if bind_annotation == &BindingAnnotation::Mutable { "mut " } else { "" };
+            let some_body = extract_body_from_arm(&arms[0])?;
+            let none_body = extract_body_from_arm(&arms[1])?;
+            let method_sugg = match &none_body.kind {
+                ExprKind::Block(..) => "map_or_else",
+                _ => "map_or",
+            };
+            let capture_name = id.name.to_ident_string();
+            let wrap_braces = should_wrap_in_braces(cx, expr);
+            let (as_ref, as_mut) = match &cond_expr.kind {
+                ExprKind::AddrOf(_, Mutability::Not, _) => (true, false),
+                ExprKind::AddrOf(_, Mutability::Mut, _) => (false, true),
+                _ => (bind_annotation == &BindingAnnotation::Ref, bind_annotation == &BindingAnnotation::RefMut),
+            };
+            let cond_expr = match &cond_expr.kind {
+                // Pointer dereferencing happens automatically, so we can omit it in the suggestion
+                ExprKind::Unary(UnOp::UnDeref, expr) | ExprKind::AddrOf(_, _, expr) => expr,
+                _ => cond_expr,
+            };
+            Some(OptionIfLetElseOccurence {
+                option: format_option_in_sugg(cx, cond_expr, as_ref, as_mut),
+                method_sugg: method_sugg.to_string(),
+                some_expr: format!("|{}{}| {}", capture_mut, capture_name, Sugg::hir(cx, some_body, "..")),
+                none_expr: format!("{}{}", if method_sugg == "map_or" { "" } else { "|| " }, Sugg::hir(cx, none_body, "..")),
+                wrap_braces,
+            })
+        } else {
+            None
+        }
+    }
+}
+
+impl<'a> LateLintPass<'a> for OptionIfLetElse {
+    fn check_expr(&mut self, cx: &LateContext<'a>, expr: &Expr<'_>) {
+        if let Some(detection) = detect_option_if_let_else(cx, expr) {
+            span_lint_and_sugg(
+                cx,
+                OPTION_IF_LET_ELSE,
+                expr.span,
+                format!("use Option::{} instead of an if let/else", detection.method_sugg).as_str(),
+                "try",
+                format!(
+                    "{}{}.{}({}, {}){}",
+                    if detection.wrap_braces { "{ " } else { "" },
+                    detection.option,
+                    detection.method_sugg,
+                    detection.none_expr,
+                    detection.some_expr,
+                    if detection.wrap_braces { " }" } else { "" },
+                ),
+                Applicability::MaybeIncorrect,
+            );
+        }
+    }
+}

clippy_lints/src/pattern_type_mismatch.rs

@@ -0,0 +1,311 @@
+use crate::utils::{last_path_segment, span_lint_and_help};
+use rustc_hir::{
+    intravisit, Body, Expr, ExprKind, FieldPat, FnDecl, HirId, LocalSource, MatchSource, Mutability, Pat, PatKind,
+    QPath, Stmt, StmtKind,
+};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::subst::SubstsRef;
+use rustc_middle::ty::{AdtDef, FieldDef, Ty, TyKind, VariantDef};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for patterns that aren't exact representations of the types
+    /// they are applied to.
+    ///
+    /// To satisfy this lint, you will have to adjust either the expression that is matched
+    /// against or the pattern itself, as well as the bindings that are introduced by the
+    /// adjusted patterns. For matching you will have to either dereference the expression
+    /// with the `*` operator, or amend the patterns to explicitly match against `&<pattern>`
+    /// or `&mut <pattern>` depending on the reference mutability. For the bindings you need
+    /// to use the inverse. You can leave them as plain bindings if you wish for the value
+    /// to be copied, but you must use `ref mut <variable>` or `ref <variable>` to construct
+    /// a reference into the matched structure.
+    ///
+    /// If you are looking for a way to learn about ownership semantics in more detail, it
+    /// is recommended to look at IDE options available to you to highlight types, lifetimes
+    /// and reference semantics in your code. The available tooling would expose these things
+    /// in a general way even outside of the various pattern matching mechanics. Of course
+    /// this lint can still be used to highlight areas of interest and ensure a good understanding
+    /// of ownership semantics.
+    ///
+    /// **Why is this bad?** It isn't bad in general. But in some contexts it can be desirable
+    /// because it increases ownership hints in the code, and will guard against some changes
+    /// in ownership.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// This example shows the basic adjustments necessary to satisfy the lint. Note how
+    /// the matched expression is explicitly dereferenced with `*` and the `inner` variable
+    /// is bound to a shared borrow via `ref inner`.
+    ///
+    /// ```rust,ignore
+    /// // Bad
+    /// let value = &Some(Box::new(23));
+    /// match value {
+    ///     Some(inner) => println!("{}", inner),
+    ///     None => println!("none"),
+    /// }
+    ///
+    /// // Good
+    /// let value = &Some(Box::new(23));
+    /// match *value {
+    ///     Some(ref inner) => println!("{}", inner),
+    ///     None => println!("none"),
+    /// }
+    /// ```
+    ///
+    /// The following example demonstrates one of the advantages of the more verbose style.
+    /// Note how the second version uses `ref mut a` to explicitly declare `a` a shared mutable
+    /// borrow, while `b` is simply taken by value. This ensures that the loop body cannot
+    /// accidentally modify the wrong part of the structure.
+    ///
+    /// ```rust,ignore
+    /// // Bad
+    /// let mut values = vec![(2, 3), (3, 4)];
+    /// for (a, b) in &mut values {
+    ///     *a += *b;
+    /// }
+    ///
+    /// // Good
+    /// let mut values = vec![(2, 3), (3, 4)];
+    /// for &mut (ref mut a, b) in &mut values {
+    ///     *a += b;
+    /// }
+    /// ```
+    pub PATTERN_TYPE_MISMATCH,
+    restriction,
+    "type of pattern does not match the expression type"
+}
+
+declare_lint_pass!(PatternTypeMismatch => [PATTERN_TYPE_MISMATCH]);
+
+impl<'tcx> LateLintPass<'tcx> for PatternTypeMismatch {
+    fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
+        if let StmtKind::Local(ref local) = stmt.kind {
+            if let Some(init) = &local.init {
+                if let Some(init_ty) = cx.tables().node_type_opt(init.hir_id) {
+                    let pat = &local.pat;
+                    if in_external_macro(cx.sess(), pat.span) {
+                        return;
+                    }
+                    let deref_possible = match local.source {
+                        LocalSource::Normal => DerefPossible::Possible,
+                        _ => DerefPossible::Impossible,
+                    };
+                    apply_lint(cx, pat, init_ty, deref_possible);
+                }
+            }
+        }
+    }
+
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if let ExprKind::Match(ref expr, arms, source) = expr.kind {
+            match source {
+                MatchSource::Normal | MatchSource::IfLetDesugar { .. } | MatchSource::WhileLetDesugar => {
+                    if let Some(expr_ty) = cx.tables().node_type_opt(expr.hir_id) {
+                        'pattern_checks: for arm in arms {
+                            let pat = &arm.pat;
+                            if in_external_macro(cx.sess(), pat.span) {
+                                continue 'pattern_checks;
+                            }
+                            if apply_lint(cx, pat, expr_ty, DerefPossible::Possible) {
+                                break 'pattern_checks;
+                            }
+                        }
+                    }
+                },
+                _ => (),
+            }
+        }
+    }
+
+    fn check_fn(
+        &mut self,
+        cx: &LateContext<'tcx>,
+        _: intravisit::FnKind<'tcx>,
+        _: &'tcx FnDecl<'_>,
+        body: &'tcx Body<'_>,
+        _: Span,
+        hir_id: HirId,
+    ) {
+        if let Some(fn_sig) = cx.tables().liberated_fn_sigs().get(hir_id) {
+            for (param, ty) in body.params.iter().zip(fn_sig.inputs().iter()) {
+                apply_lint(cx, &param.pat, ty, DerefPossible::Impossible);
+            }
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum DerefPossible {
+    Possible,
+    Impossible,
+}
+
+fn apply_lint<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>, expr_ty: Ty<'tcx>, deref_possible: DerefPossible) -> bool {
+    let maybe_mismatch = find_first_mismatch(cx, pat, expr_ty, Level::Top);
+    if let Some((span, mutability, level)) = maybe_mismatch {
+        span_lint_and_help(
+            cx,
+            PATTERN_TYPE_MISMATCH,
+            span,
+            "type of pattern does not match the expression type",
+            None,
+            &format!(
+                "{}explicitly match against a `{}` pattern and adjust the enclosed variable bindings",
+                match (deref_possible, level) {
+                    (DerefPossible::Possible, Level::Top) => "use `*` to dereference the match expression or ",
+                    _ => "",
+                },
+                match mutability {
+                    Mutability::Mut => "&mut _",
+                    Mutability::Not => "&_",
+                },
+            ),
+        );
+        true
+    } else {
+        false
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+enum Level {
+    Top,
+    Lower,
+}
+
+#[allow(rustc::usage_of_ty_tykind)]
+fn find_first_mismatch<'tcx>(
+    cx: &LateContext<'tcx>,
+    pat: &Pat<'_>,
+    ty: Ty<'tcx>,
+    level: Level,
+) -> Option<(Span, Mutability, Level)> {
+    if let PatKind::Ref(ref sub_pat, _) = pat.kind {
+        if let TyKind::Ref(_, sub_ty, _) = ty.kind {
+            return find_first_mismatch(cx, sub_pat, sub_ty, Level::Lower);
+        }
+    }
+
+    if let TyKind::Ref(_, _, mutability) = ty.kind {
+        if is_non_ref_pattern(&pat.kind) {
+            return Some((pat.span, mutability, level));
+        }
+    }
+
+    if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.kind {
+        if let TyKind::Adt(ref adt_def, ref substs_ref) = ty.kind {
+            if let Some(variant) = get_variant(adt_def, qpath) {
+                let field_defs = &variant.fields;
+                return find_first_mismatch_in_struct(cx, field_pats, field_defs, substs_ref);
+            }
+        }
+    }
+
+    if let PatKind::TupleStruct(ref qpath, ref pats, _) = pat.kind {
+        if let TyKind::Adt(ref adt_def, ref substs_ref) = ty.kind {
+            if let Some(variant) = get_variant(adt_def, qpath) {
+                let field_defs = &variant.fields;
+                let ty_iter = field_defs.iter().map(|field_def| field_def.ty(cx.tcx, substs_ref));
+                return find_first_mismatch_in_tuple(cx, pats, ty_iter);
+            }
+        }
+    }
+
+    if let PatKind::Tuple(ref pats, _) = pat.kind {
+        if let TyKind::Tuple(..) = ty.kind {
+            return find_first_mismatch_in_tuple(cx, pats, ty.tuple_fields());
+        }
+    }
+
+    if let PatKind::Or(sub_pats) = pat.kind {
+        for pat in sub_pats {
+            let maybe_mismatch = find_first_mismatch(cx, pat, ty, level);
+            if let Some(mismatch) = maybe_mismatch {
+                return Some(mismatch);
+            }
+        }
+    }
+
+    None
+}
+
+fn get_variant<'a>(adt_def: &'a AdtDef, qpath: &QPath<'_>) -> Option<&'a VariantDef> {
+    if adt_def.is_struct() {
+        if let Some(variant) = adt_def.variants.iter().next() {
+            return Some(variant);
+        }
+    }
+
+    if adt_def.is_enum() {
+        let pat_ident = last_path_segment(qpath).ident;
+        for variant in &adt_def.variants {
+            if variant.ident == pat_ident {
+                return Some(variant);
+            }
+        }
+    }
+
+    None
+}
+
+fn find_first_mismatch_in_tuple<'tcx, I>(
+    cx: &LateContext<'tcx>,
+    pats: &[&Pat<'_>],
+    ty_iter_src: I,
+) -> Option<(Span, Mutability, Level)>
+where
+    I: IntoIterator<Item = Ty<'tcx>>,
+{
+    let mut field_tys = ty_iter_src.into_iter();
+    'fields: for pat in pats {
+        let field_ty = if let Some(ty) = field_tys.next() {
+            ty
+        } else {
+            break 'fields;
+        };
+
+        let maybe_mismatch = find_first_mismatch(cx, pat, field_ty, Level::Lower);
+        if let Some(mismatch) = maybe_mismatch {
+            return Some(mismatch);
+        }
+    }
+
+    None
+}
+
+fn find_first_mismatch_in_struct<'tcx>(
+    cx: &LateContext<'tcx>,
+    field_pats: &[FieldPat<'_>],
+    field_defs: &[FieldDef],
+    substs_ref: SubstsRef<'tcx>,
+) -> Option<(Span, Mutability, Level)> {
+    for field_pat in field_pats {
+        'definitions: for field_def in field_defs {
+            if field_pat.ident == field_def.ident {
+                let field_ty = field_def.ty(cx.tcx, substs_ref);
+                let pat = &field_pat.pat;
+                let maybe_mismatch = find_first_mismatch(cx, pat, field_ty, Level::Lower);
+                if let Some(mismatch) = maybe_mismatch {
+                    return Some(mismatch);
+                }
+                break 'definitions;
+            }
+        }
+    }
+
+    None
+}
+
+fn is_non_ref_pattern(pat_kind: &PatKind<'_>) -> bool {
+    match pat_kind {
+        PatKind::Struct(..) | PatKind::Tuple(..) | PatKind::TupleStruct(..) | PatKind::Path(..) => true,
+        PatKind::Or(sub_pats) => sub_pats.iter().any(|pat| is_non_ref_pattern(&pat.kind)),
+        _ => false,
+    }
+}

clippy_lints/src/precedence.rs

@@ -148,17 +148,11 @@ fn is_arith_expr(expr: &Expr) -> bool {
 #[must_use]
 fn is_bit_op(op: BinOpKind) -> bool {
     use rustc_ast::ast::BinOpKind::{BitAnd, BitOr, BitXor, Shl, Shr};
-    match op {
+    matches!(op, BitXor | BitAnd | BitOr | Shl | Shr)
-        BitXor | BitAnd | BitOr | Shl | Shr => true,
-        _ => false,
-    }
 }
 
 #[must_use]
 fn is_arith_op(op: BinOpKind) -> bool {
     use rustc_ast::ast::BinOpKind::{Add, Div, Mul, Rem, Sub};
-    match op {
+    matches!(op, Add | Sub | Mul | Div | Rem)
-        Add | Sub | Mul | Div | Rem => true,
-        _ => false,
-    }
 }

clippy_lints/src/ranges.rs

@@ -52,6 +52,11 @@ declare_clippy_lint! {
     /// exclusive ranges, because they essentially add an extra branch that
     /// LLVM may fail to hoist out of the loop.
     ///
+    /// This will cause a warning that cannot be fixed if the consumer of the
+    /// range only accepts a specific range type, instead of the generic
+    /// `RangeBounds` trait
+    /// ([#3307](https://github.com/rust-lang/rust-clippy/issues/3307)).
+    ///
     /// **Example:**
     /// ```rust,ignore
     /// for x..(y+1) { .. }
@@ -72,7 +77,10 @@ declare_clippy_lint! {
     /// **Why is this bad?** The code is more readable with an exclusive range
     /// like `x..y`.
     ///
-    /// **Known problems:** None.
+    /// **Known problems:** This will cause a warning that cannot be fixed if
+    /// the consumer of the range only accepts a specific range type, instead of
+    /// the generic `RangeBounds` trait
+    /// ([#3307](https://github.com/rust-lang/rust-clippy/issues/3307)).
     ///
     /// **Example:**
     /// ```rust,ignore
@@ -83,7 +91,7 @@ declare_clippy_lint! {
     /// for x..y { .. }
     /// ```
     pub RANGE_MINUS_ONE,
-    complexity,
+    pedantic,
     "`x..=(y-1)` reads better as `x..y`"
 }
 

clippy_lints/src/redundant_pattern_matching.rs

@@ -1,260 +0,0 @@
-use crate::utils::{in_constant, match_qpath, match_trait_method, paths, snippet, span_lint_and_then};
-use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
-use rustc_errors::Applicability;
-use rustc_hir::{Arm, Expr, ExprKind, HirId, MatchSource, PatKind, QPath};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty;
-use rustc_mir::const_eval::is_const_fn;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Symbol;
-
-declare_clippy_lint! {
-    /// **What it does:** Lint for redundant pattern matching over `Result` or
-    /// `Option`
-    ///
-    /// **Why is this bad?** It's more concise and clear to just use the proper
-    /// utility function
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    ///
-    /// ```rust
-    /// if let Ok(_) = Ok::<i32, i32>(42) {}
-    /// if let Err(_) = Err::<i32, i32>(42) {}
-    /// if let None = None::<()> {}
-    /// if let Some(_) = Some(42) {}
-    /// match Ok::<i32, i32>(42) {
-    ///     Ok(_) => true,
-    ///     Err(_) => false,
-    /// };
-    /// ```
-    ///
-    /// The more idiomatic use would be:
-    ///
-    /// ```rust
-    /// if Ok::<i32, i32>(42).is_ok() {}
-    /// if Err::<i32, i32>(42).is_err() {}
-    /// if None::<()>.is_none() {}
-    /// if Some(42).is_some() {}
-    /// Ok::<i32, i32>(42).is_ok();
-    /// ```
-    pub REDUNDANT_PATTERN_MATCHING,
-    style,
-    "use the proper utility function avoiding an `if let`"
-}
-
-declare_lint_pass!(RedundantPatternMatching => [REDUNDANT_PATTERN_MATCHING]);
-
-impl<'tcx> LateLintPass<'tcx> for RedundantPatternMatching {
-    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let ExprKind::Match(op, arms, ref match_source) = &expr.kind {
-            match match_source {
-                MatchSource::Normal => find_sugg_for_match(cx, expr, op, arms),
-                MatchSource::IfLetDesugar { .. } => find_sugg_for_if_let(cx, expr, op, arms, "if"),
-                MatchSource::WhileLetDesugar => find_sugg_for_if_let(cx, expr, op, arms, "while"),
-                _ => return,
-            }
-        }
-    }
-}
-
-fn find_sugg_for_if_let<'tcx>(
-    cx: &LateContext<'tcx>,
-    expr: &'tcx Expr<'_>,
-    op: &Expr<'_>,
-    arms: &[Arm<'_>],
-    keyword: &'static str,
-) {
-    fn find_suggestion(cx: &LateContext<'_>, hir_id: HirId, path: &QPath<'_>) -> Option<&'static str> {
-        if match_qpath(path, &paths::RESULT_OK) && can_suggest(cx, hir_id, sym!(result_type), "is_ok") {
-            return Some("is_ok()");
-        }
-        if match_qpath(path, &paths::RESULT_ERR) && can_suggest(cx, hir_id, sym!(result_type), "is_err") {
-            return Some("is_err()");
-        }
-        if match_qpath(path, &paths::OPTION_SOME) && can_suggest(cx, hir_id, sym!(option_type), "is_some") {
-            return Some("is_some()");
-        }
-        if match_qpath(path, &paths::OPTION_NONE) && can_suggest(cx, hir_id, sym!(option_type), "is_none") {
-            return Some("is_none()");
-        }
-        None
-    }
-
-    let hir_id = expr.hir_id;
-    let good_method = match arms[0].pat.kind {
-        PatKind::TupleStruct(ref path, ref patterns, _) if patterns.len() == 1 => {
-            if let PatKind::Wild = patterns[0].kind {
-                find_suggestion(cx, hir_id, path)
-            } else {
-                None
-            }
-        },
-        PatKind::Path(ref path) => find_suggestion(cx, hir_id, path),
-        _ => None,
-    };
-    let good_method = match good_method {
-        Some(method) => method,
-        None => return,
-    };
-
-    // check that `while_let_on_iterator` lint does not trigger
-    if_chain! {
-        if keyword == "while";
-        if let ExprKind::MethodCall(method_path, _, _, _) = op.kind;
-        if method_path.ident.name == sym!(next);
-        if match_trait_method(cx, op, &paths::ITERATOR);
-        then {
-            return;
-        }
-    }
-
-    span_lint_and_then(
-        cx,
-        REDUNDANT_PATTERN_MATCHING,
-        arms[0].pat.span,
-        &format!("redundant pattern matching, consider using `{}`", good_method),
-        |diag| {
-            // while let ... = ... { ... }
-            // ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-            let expr_span = expr.span;
-
-            // while let ... = ... { ... }
-            //                 ^^^
-            let op_span = op.span.source_callsite();
-
-            // while let ... = ... { ... }
-            // ^^^^^^^^^^^^^^^^^^^
-            let span = expr_span.until(op_span.shrink_to_hi());
-            diag.span_suggestion(
-                span,
-                "try this",
-                format!("{} {}.{}", keyword, snippet(cx, op_span, "_"), good_method),
-                Applicability::MachineApplicable, // snippet
-            );
-        },
-    );
-}
-
-fn find_sugg_for_match<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, op: &Expr<'_>, arms: &[Arm<'_>]) {
-    if arms.len() == 2 {
-        let node_pair = (&arms[0].pat.kind, &arms[1].pat.kind);
-
-        let hir_id = expr.hir_id;
-        let found_good_method = match node_pair {
-            (
-                PatKind::TupleStruct(ref path_left, ref patterns_left, _),
-                PatKind::TupleStruct(ref path_right, ref patterns_right, _),
-            ) if patterns_left.len() == 1 && patterns_right.len() == 1 => {
-                if let (PatKind::Wild, PatKind::Wild) = (&patterns_left[0].kind, &patterns_right[0].kind) {
-                    find_good_method_for_match(
-                        arms,
-                        path_left,
-                        path_right,
-                        &paths::RESULT_OK,
-                        &paths::RESULT_ERR,
-                        "is_ok()",
-                        "is_err()",
-                        || can_suggest(cx, hir_id, sym!(result_type), "is_ok"),
-                        || can_suggest(cx, hir_id, sym!(result_type), "is_err"),
-                    )
-                } else {
-                    None
-                }
-            },
-            (PatKind::TupleStruct(ref path_left, ref patterns, _), PatKind::Path(ref path_right))
-            | (PatKind::Path(ref path_left), PatKind::TupleStruct(ref path_right, ref patterns, _))
-                if patterns.len() == 1 =>
-            {
-                if let PatKind::Wild = patterns[0].kind {
-                    find_good_method_for_match(
-                        arms,
-                        path_left,
-                        path_right,
-                        &paths::OPTION_SOME,
-                        &paths::OPTION_NONE,
-                        "is_some()",
-                        "is_none()",
-                        || can_suggest(cx, hir_id, sym!(option_type), "is_some"),
-                        || can_suggest(cx, hir_id, sym!(option_type), "is_none"),
-                    )
-                } else {
-                    None
-                }
-            },
-            _ => None,
-        };
-
-        if let Some(good_method) = found_good_method {
-            span_lint_and_then(
-                cx,
-                REDUNDANT_PATTERN_MATCHING,
-                expr.span,
-                &format!("redundant pattern matching, consider using `{}`", good_method),
-                |diag| {
-                    let span = expr.span.to(op.span);
-                    diag.span_suggestion(
-                        span,
-                        "try this",
-                        format!("{}.{}", snippet(cx, op.span, "_"), good_method),
-                        Applicability::MaybeIncorrect, // snippet
-                    );
-                },
-            );
-        }
-    }
-}
-
-#[allow(clippy::too_many_arguments)]
-fn find_good_method_for_match<'a>(
-    arms: &[Arm<'_>],
-    path_left: &QPath<'_>,
-    path_right: &QPath<'_>,
-    expected_left: &[&str],
-    expected_right: &[&str],
-    should_be_left: &'a str,
-    should_be_right: &'a str,
-    can_suggest_left: impl Fn() -> bool,
-    can_suggest_right: impl Fn() -> bool,
-) -> Option<&'a str> {
-    let body_node_pair = if match_qpath(path_left, expected_left) && match_qpath(path_right, expected_right) {
-        (&(*arms[0].body).kind, &(*arms[1].body).kind)
-    } else if match_qpath(path_right, expected_left) && match_qpath(path_left, expected_right) {
-        (&(*arms[1].body).kind, &(*arms[0].body).kind)
-    } else {
-        return None;
-    };
-
-    match body_node_pair {
-        (ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => match (&lit_left.node, &lit_right.node) {
-            (LitKind::Bool(true), LitKind::Bool(false)) if can_suggest_left() => Some(should_be_left),
-            (LitKind::Bool(false), LitKind::Bool(true)) if can_suggest_right() => Some(should_be_right),
-            _ => None,
-        },
-        _ => None,
-    }
-}
-
-fn can_suggest(cx: &LateContext<'_>, hir_id: HirId, diag_item: Symbol, name: &str) -> bool {
-    if !in_constant(cx, hir_id) {
-        return true;
-    }
-
-    // Avoid suggesting calls to non-`const fn`s in const contexts, see #5697.
-    cx.tcx
-        .get_diagnostic_item(diag_item)
-        .and_then(|def_id| {
-            cx.tcx.inherent_impls(def_id).iter().find_map(|imp| {
-                cx.tcx
-                    .associated_items(*imp)
-                    .in_definition_order()
-                    .find_map(|item| match item.kind {
-                        ty::AssocKind::Fn if item.ident.name.as_str() == name => Some(item.def_id),
-                        _ => None,
-                    })
-            })
-        })
-        .map_or(false, |def_id| is_const_fn(cx.tcx, def_id))
-}

clippy_lints/src/regex.rs

@@ -1,9 +1,9 @@
 use crate::consts::{constant, Constant};
-use crate::utils::{is_expn_of, match_def_path, match_type, paths, span_lint, span_lint_and_help};
+use crate::utils::{match_def_path, paths, span_lint, span_lint_and_help};
 use if_chain::if_chain;
 use rustc_ast::ast::{LitKind, StrStyle};
 use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::{Block, BorrowKind, Crate, Expr, ExprKind, HirId};
+use rustc_hir::{BorrowKind, Expr, ExprKind, HirId};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::{BytePos, Span};
@@ -46,66 +46,15 @@ declare_clippy_lint! {
     "trivial regular expressions"
 }
 
-declare_clippy_lint! {
-    /// **What it does:** Checks for usage of `regex!(_)` which (as of now) is
-    /// usually slower than `Regex::new(_)` unless called in a loop (which is a bad
-    /// idea anyway).
-    ///
-    /// **Why is this bad?** Performance, at least for now. The macro version is
-    /// likely to catch up long-term, but for now the dynamic version is faster.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```ignore
-    /// regex!("foo|bar")
-    /// ```
-    pub REGEX_MACRO,
-    style,
-    "use of `regex!(_)` instead of `Regex::new(_)`"
-}
-
 #[derive(Clone, Default)]
 pub struct Regex {
     spans: FxHashSet<Span>,
     last: Option<HirId>,
 }
 
-impl_lint_pass!(Regex => [INVALID_REGEX, REGEX_MACRO, TRIVIAL_REGEX]);
+impl_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]);
 
 impl<'tcx> LateLintPass<'tcx> for Regex {
-    fn check_crate(&mut self, _: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
-        self.spans.clear();
-    }
-
-    fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'_>) {
-        if_chain! {
-            if self.last.is_none();
-            if let Some(ref expr) = block.expr;
-            if match_type(cx, cx.tables().expr_ty(expr), &paths::REGEX);
-            if let Some(span) = is_expn_of(expr.span, "regex");
-            then {
-                if !self.spans.contains(&span) {
-                    span_lint(
-                        cx,
-                        REGEX_MACRO,
-                        span,
-                        "`regex!(_)` found. \
-                        Please use `Regex::new(_)`, which is faster for now."
-                    );
-                    self.spans.insert(span);
-                }
-                self.last = Some(block.hir_id);
-            }
-        }
-    }
-
-    fn check_block_post(&mut self, _: &LateContext<'tcx>, block: &'tcx Block<'_>) {
-        if self.last.map_or(false, |id| block.hir_id == id) {
-            self.last = None;
-        }
-    }
-
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
             if let ExprKind::Call(ref fun, ref args) = expr.kind;
@@ -150,12 +99,7 @@ fn is_trivial_regex(s: &regex_syntax::hir::Hir) -> Option<&'static str> {
     use regex_syntax::hir::Anchor::{EndText, StartText};
     use regex_syntax::hir::HirKind::{Alternation, Anchor, Concat, Empty, Literal};
 
-    let is_literal = |e: &[regex_syntax::hir::Hir]| {
+    let is_literal = |e: &[regex_syntax::hir::Hir]| e.iter().all(|e| matches!(*e.kind(), Literal(_)));
-        e.iter().all(|e| match *e.kind() {
-            Literal(_) => true,
-            _ => false,
-        })
-    };
 
     match *s.kind() {
         Empty | Anchor(_) => Some("the regex is unlikely to be useful as it is"),

clippy_lints/src/repeat_once.rs

@@ -0,0 +1,82 @@
+use crate::consts::{constant_context, Constant};
+use crate::utils::{in_macro, is_type_diagnostic_item, snippet, span_lint_and_sugg, walk_ptrs_ty};
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for usage of `.repeat(1)` and suggest the following method for each types.
+    /// - `.to_string()` for `str`
+    /// - `.clone()` for `String`
+    /// - `.to_vec()` for `slice`
+    ///
+    /// **Why is this bad?** For example, `String.repeat(1)` is equivalent to `.clone()`. If cloning the string is the intention behind this, `clone()` should be used.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// fn main() {
+    ///     let x = String::from("hello world").repeat(1);
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// fn main() {
+    ///     let x = String::from("hello world").clone();
+    /// }
+    /// ```
+    pub REPEAT_ONCE,
+    complexity,
+    "using `.repeat(1)` instead of `String.clone()`, `str.to_string()` or `slice.to_vec()` "
+}
+
+declare_lint_pass!(RepeatOnce => [REPEAT_ONCE]);
+
+impl<'tcx> LateLintPass<'tcx> for RepeatOnce {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
+        if_chain! {
+            if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
+            if path.ident.name == sym!(repeat);
+            if let Some(Constant::Int(1)) = constant_context(cx, cx.tables()).expr(&args[1]);
+            if !in_macro(args[0].span);
+            then {
+                let ty = walk_ptrs_ty(cx.tables().expr_ty(&args[0]));
+                if ty.is_str() {
+                    span_lint_and_sugg(
+                        cx,
+                        REPEAT_ONCE,
+                        expr.span,
+                        "calling `repeat(1)` on str",
+                        "consider using `.to_string()` instead",
+                        format!("{}.to_string()", snippet(cx, args[0].span, r#""...""#)),
+                        Applicability::MachineApplicable,
+                    );
+                } else if ty.builtin_index().is_some() {
+                    span_lint_and_sugg(
+                        cx,
+                        REPEAT_ONCE,
+                        expr.span,
+                        "calling `repeat(1)` on slice",
+                        "consider using `.to_vec()` instead",
+                        format!("{}.to_vec()", snippet(cx, args[0].span, r#""...""#)),
+                        Applicability::MachineApplicable,
+                    );
+                } else if is_type_diagnostic_item(cx, ty, sym!(string_type)) {
+                    span_lint_and_sugg(
+                        cx,
+                        REPEAT_ONCE,
+                        expr.span,
+                        "calling `repeat(1)` on a string literal",
+                        "consider using `.clone()` instead",
+                        format!("{}.clone()", snippet(cx, args[0].span, r#""...""#)),
+                        Applicability::MachineApplicable,
+                    );
+                }
+            }
+        }
+    }
+}

clippy_lints/src/returns.rs

@@ -259,15 +259,15 @@ fn is_unit_expr(expr: &ast::Expr) -> bool {
 
 fn lint_unneeded_unit_return(cx: &EarlyContext<'_>, ty: &ast::Ty, span: Span) {
     let (ret_span, appl) = if let Ok(fn_source) = cx.sess().source_map().span_to_snippet(span.with_hi(ty.span.hi())) {
-        if let Some(rpos) = fn_source.rfind("->") {
+        fn_source
-            #[allow(clippy::cast_possible_truncation)]
+            .rfind("->")
-            (
+            .map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
-                ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
+                (
-                Applicability::MachineApplicable,
+                    #[allow(clippy::cast_possible_truncation)]
-            )
+                    ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
-        } else {
+                    Applicability::MachineApplicable,
-            (ty.span, Applicability::MaybeIncorrect)
+                )
-        }
+            })
     } else {
         (ty.span, Applicability::MaybeIncorrect)
     };

clippy_lints/src/shadow.rs

@@ -165,14 +165,7 @@ fn check_local<'tcx>(cx: &LateContext<'tcx>, local: &'tcx Local<'_>, bindings: &
 
 fn is_binding(cx: &LateContext<'_>, pat_id: HirId) -> bool {
     let var_ty = cx.tables().node_type_opt(pat_id);
-    if let Some(var_ty) = var_ty {
+    var_ty.map_or(false, |var_ty| !matches!(var_ty.kind, ty::Adt(..)))
-        match var_ty.kind {
-            ty::Adt(..) => false,
-            _ => true,
-        }
-    } else {
-        false
-    }
 }
 
 fn check_pat<'tcx>(

clippy_lints/src/temporary_assignment.rs

@@ -25,13 +25,7 @@ declare_clippy_lint! {
 fn is_temporary(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     match &expr.kind {
         ExprKind::Struct(..) | ExprKind::Tup(..) => true,
-        ExprKind::Path(qpath) => {
+        ExprKind::Path(qpath) => matches!(cx.qpath_res(qpath, expr.hir_id), Res::Def(DefKind::Const, ..)),
-            if let Res::Def(DefKind::Const, ..) = cx.qpath_res(qpath, expr.hir_id) {
-                true
-            } else {
-                false
-            }
-        },
         _ => false,
     }
 }

clippy_lints/src/trait_bounds.rs

@@ -1,19 +1,19 @@
 use crate::utils::{in_macro, snippet, snippet_with_applicability, span_lint_and_help, SpanlessHash};
+use if_chain::if_chain;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::Applicability;
 use rustc_hir::{GenericBound, Generics, WherePredicate};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 
-#[derive(Copy, Clone)]
-pub struct TraitBounds;
-
 declare_clippy_lint! {
     /// **What it does:** This lint warns about unnecessary type repetitions in trait bounds
     ///
     /// **Why is this bad?** Repeating the type for every bound makes the code
     /// less readable than combining the bounds
     ///
+    /// **Known problems:** None.
+    ///
     /// **Example:**
     /// ```rust
     /// pub fn foo<T>(t: T) where T: Copy, T: Clone {}
@@ -29,6 +29,18 @@ declare_clippy_lint! {
     "Types are repeated unnecessary in trait bounds use `+` instead of using `T: _, T: _`"
 }
 
+#[derive(Copy, Clone)]
+pub struct TraitBounds {
+    max_trait_bounds: u64,
+}
+
+impl TraitBounds {
+    #[must_use]
+    pub fn new(max_trait_bounds: u64) -> Self {
+        Self { max_trait_bounds }
+    }
+}
+
 impl_lint_pass!(TraitBounds => [TYPE_REPETITION_IN_BOUNDS]);
 
 impl<'tcx> LateLintPass<'tcx> for TraitBounds {
@@ -44,9 +56,14 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
         let mut map = FxHashMap::default();
         let mut applicability = Applicability::MaybeIncorrect;
         for bound in gen.where_clause.predicates {
-            if let WherePredicate::BoundPredicate(ref p) = bound {
+            if_chain! {
+                if let WherePredicate::BoundPredicate(ref p) = bound;
+                if p.bounds.len() as u64 <= self.max_trait_bounds;
+                if !in_macro(p.span);
                 let h = hash(&p.bounded_ty);
-                if let Some(ref v) = map.insert(h, p.bounds.iter().collect::<Vec<_>>()) {
+                if let Some(ref v) = map.insert(h, p.bounds.iter().collect::<Vec<_>>());
+
+                then {
                     let mut hint_string = format!(
                         "consider combining the bounds: `{}:",
                         snippet(cx, p.bounded_ty.span, "_")

clippy_lints/src/types.rs

@@ -775,11 +775,7 @@ impl<'tcx> LateLintPass<'tcx> for UnitArg {
                     .iter()
                     .filter(|arg| {
                         if is_unit(cx.tables().expr_ty(arg)) && !is_unit_literal(arg) {
-                            if let ExprKind::Match(.., MatchSource::TryDesugar) = &arg.kind {
+                            !matches!(&arg.kind, ExprKind::Match(.., MatchSource::TryDesugar))
-                                false
-                            } else {
-                                true
-                            }
                         } else {
                             false
                         }
@@ -899,17 +895,11 @@ fn is_questionmark_desugar_marked_call(expr: &Expr<'_>) -> bool {
 }
 
 fn is_unit(ty: Ty<'_>) -> bool {
-    match ty.kind {
+    matches!(ty.kind, ty::Tuple(slice) if slice.is_empty())
-        ty::Tuple(slice) if slice.is_empty() => true,
-        _ => false,
-    }
 }
 
 fn is_unit_literal(expr: &Expr<'_>) -> bool {
-    match expr.kind {
+    matches!(expr.kind, ExprKind::Tup(ref slice) if slice.is_empty())
-        ExprKind::Tup(ref slice) if slice.is_empty() => true,
-        _ => false,
-    }
 }
 
 declare_clippy_lint! {
@@ -1154,10 +1144,7 @@ fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_>) -> u64 {
 }
 
 fn is_isize_or_usize(typ: Ty<'_>) -> bool {
-    match typ.kind {
+    matches!(typ.kind, ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize))
-        ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => true,
-        _ => false,
-    }
 }
 
 fn span_precision_loss_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to_f64: bool) {
@@ -1205,16 +1192,19 @@ fn span_lossless_lint(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast
     // has parens on the outside, they are no longer needed.
     let mut applicability = Applicability::MachineApplicable;
     let opt = snippet_opt(cx, op.span);
-    let sugg = if let Some(ref snip) = opt {
+    let sugg = opt.as_ref().map_or_else(
-        if should_strip_parens(op, snip) {
+        || {
-            &snip[1..snip.len() - 1]
+            applicability = Applicability::HasPlaceholders;
-        } else {
+            ".."
-            snip.as_str()
+        },
-        }
+        |snip| {
-    } else {
+            if should_strip_parens(op, snip) {
-        applicability = Applicability::HasPlaceholders;
+                &snip[1..snip.len() - 1]
-        ".."
+            } else {
-    };
+                snip.as_str()
+            }
+        },
+    );
 
     span_lint_and_sugg(
         cx,
@@ -1734,10 +1724,10 @@ impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
 
             TyKind::TraitObject(ref param_bounds, _) => {
                 let has_lifetime_parameters = param_bounds.iter().any(|bound| {
-                    bound.bound_generic_params.iter().any(|gen| match gen.kind {
+                    bound
-                        GenericParamKind::Lifetime { .. } => true,
+                        .bound_generic_params
-                        _ => false,
+                        .iter()
-                    })
+                        .any(|gen| matches!(gen.kind, GenericParamKind::Lifetime { .. }))
                 });
                 if has_lifetime_parameters {
                     // complex trait bounds like A<'a, 'b>

clippy_lints/src/unnamed_address.rs

@@ -58,10 +58,10 @@ declare_lint_pass!(UnnamedAddress => [FN_ADDRESS_COMPARISONS, VTABLE_ADDRESS_COM
 impl LateLintPass<'_> for UnnamedAddress {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
         fn is_comparison(binop: BinOpKind) -> bool {
-            match binop {
+            matches!(
-                BinOpKind::Eq | BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ne | BinOpKind::Ge | BinOpKind::Gt => true,
+                binop,
-                _ => false,
+                BinOpKind::Eq | BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ne | BinOpKind::Ge | BinOpKind::Gt
-            }
+            )
         }
 
         fn is_trait_ptr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
@@ -72,11 +72,7 @@ impl LateLintPass<'_> for UnnamedAddress {
         }
 
         fn is_fn_def(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
-            if let ty::FnDef(..) = cx.tables().expr_ty(expr).kind {
+            matches!(cx.tables().expr_ty(expr).kind, ty::FnDef(..))
-                true
-            } else {
-                false
-            }
         }
 
         if_chain! {

clippy_lints/src/unnecessary_sort_by.rs

@@ -5,24 +5,23 @@ use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, Mutability, Param, Pat, PatKind, Path, PathSegment, QPath};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{self, subst::GenericArgKind};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::symbol::Ident;
 
 declare_clippy_lint! {
     /// **What it does:**
-    /// Detects when people use `Vec::sort_by` and pass in a function
+    /// Detects uses of `Vec::sort_by` passing in a closure
     /// which compares the two arguments, either directly or indirectly.
     ///
     /// **Why is this bad?**
     /// It is more clear to use `Vec::sort_by_key` (or `Vec::sort` if
-    /// possible) than to use `Vec::sort_by` and and a more complicated
+    /// possible) than to use `Vec::sort_by` and a more complicated
     /// closure.
     ///
     /// **Known problems:**
-    /// If the suggested `Vec::sort_by_key` uses Reverse and it isn't
+    /// If the suggested `Vec::sort_by_key` uses Reverse and it isn't already
-    /// imported by a use statement in the current frame, then a `use`
+    /// imported by a use statement, then it will need to be added manually.
-    /// statement that imports it will need to be added (which this lint
-    /// can't do).
     ///
     /// **Example:**
     ///
@@ -201,28 +200,41 @@ fn detect_lint(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<LintTrigger> {
             };
             let vec_name = Sugg::hir(cx, &args[0], "..").to_string();
             let unstable = name == "sort_unstable_by";
+
             if_chain! {
                 if let ExprKind::Path(QPath::Resolved(_, Path {
                     segments: [PathSegment { ident: left_name, .. }], ..
                 })) = &left_expr.kind;
                 if left_name == left_ident;
                 then {
-                    Some(LintTrigger::Sort(SortDetection { vec_name, unstable }))
+                    return Some(LintTrigger::Sort(SortDetection { vec_name, unstable }))
-                }
+                } else {
-                else {
+                    if !key_returns_borrow(cx, left_expr) {
-                    Some(LintTrigger::SortByKey(SortByKeyDetection {
+                        return Some(LintTrigger::SortByKey(SortByKeyDetection {
-                        vec_name,
+                            vec_name,
-                        unstable,
+                            unstable,
-                        closure_arg,
+                            closure_arg,
-                        closure_body,
+                            closure_body,
-                        reverse
+                            reverse
-                    }))
+                        }))
+                    }
                 }
             }
-        } else {
-            None
         }
     }
+
+    None
+}
+
+fn key_returns_borrow(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+    if let Some(def_id) = utils::fn_def_id(cx, expr) {
+        let output = cx.tcx.fn_sig(def_id).output();
+        let ty = output.skip_binder();
+        return matches!(ty.kind, ty::Ref(..))
+            || ty.walk().any(|arg| matches!(arg.unpack(), GenericArgKind::Lifetime(_)));
+    }
+
+    false
 }
 
 impl LateLintPass<'_> for UnnecessarySortBy {

clippy_lints/src/unnested_or_patterns.rs

@@ -72,8 +72,8 @@ impl EarlyLintPass for UnnestedOrPatterns {
 }
 
 fn lint_unnested_or_patterns(cx: &EarlyContext<'_>, pat: &Pat) {
-    if !cx.sess.opts.unstable_features.is_nightly_build() {
+    if !cx.sess.features_untracked().or_patterns {
-        // User cannot do `#![feature(or_patterns)]`, so bail.
+        // Do not suggest nesting the patterns if the feature `or_patterns` is not enabled.
         return;
     }
 
@@ -400,8 +400,8 @@ fn extend_with_matching(
 
 /// Are the patterns in `ps1` and `ps2` equal save for `ps1[idx]` compared to `ps2[idx]`?
 fn eq_pre_post(ps1: &[P<Pat>], ps2: &[P<Pat>], idx: usize) -> bool {
-    ps1[idx].is_rest() == ps2[idx].is_rest() // Avoid `[x, ..] | [x, 0]` => `[x, .. | 0]`.
+    ps1.len() == ps2.len()
-        && ps1.len() == ps2.len()
+        && ps1[idx].is_rest() == ps2[idx].is_rest() // Avoid `[x, ..] | [x, 0]` => `[x, .. | 0]`.
         && over(&ps1[..idx], &ps2[..idx], |l, r| eq_pat(l, r))
         && over(&ps1[idx + 1..], &ps2[idx + 1..], |l, r| eq_pat(l, r))
 }

clippy_lints/src/use_self.rs

@@ -167,14 +167,11 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
             if let TyKind::Path(QPath::Resolved(_, ref item_path)) = item_type.kind;
             then {
                 let parameters = &item_path.segments.last().expect(SEGMENTS_MSG).args;
-                let should_check = if let Some(ref params) = *parameters {
+                let should_check = parameters.as_ref().map_or(
-                    !params.parenthesized && !params.args.iter().any(|arg| match arg {
+                    true,
-                        GenericArg::Lifetime(_) => true,
+                    |params| !params.parenthesized
-                        _ => false,
+                        &&!params.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)))
-                    })
+                );
-                } else {
-                    true
-                };
 
                 if should_check {
                     let visitor = &mut UseSelfVisitor {

clippy_lints/src/utils/ast_utils.rs

@@ -387,10 +387,7 @@ pub fn eq_use_tree_kind(l: &UseTreeKind, r: &UseTreeKind) -> bool {
 }
 
 pub fn eq_defaultness(l: Defaultness, r: Defaultness) -> bool {
-    match (l, r) {
+    matches!((l, r), (Defaultness::Final, Defaultness::Final) | (Defaultness::Default(_), Defaultness::Default(_)))
-        (Defaultness::Final, Defaultness::Final) | (Defaultness::Default(_), Defaultness::Default(_)) => true,
-        _ => false,
-    }
 }
 
 pub fn eq_vis(l: &Visibility, r: &Visibility) -> bool {

clippy_lints/src/utils/attrs.rs

@@ -65,42 +65,45 @@ pub fn get_attr<'a>(
         };
         let attr_segments = &attr.path.segments;
         if attr_segments.len() == 2 && attr_segments[0].ident.to_string() == "clippy" {
-            if let Some(deprecation_status) =
+            BUILTIN_ATTRIBUTES
-                BUILTIN_ATTRIBUTES
+                .iter()
-                    .iter()
+                .find_map(|(builtin_name, deprecation_status)| {
-                    .find_map(|(builtin_name, deprecation_status)| {
+                    if *builtin_name == attr_segments[1].ident.to_string() {
-                        if *builtin_name == attr_segments[1].ident.to_string() {
+                        Some(deprecation_status)
-                            Some(deprecation_status)
+                    } else {
-                        } else {
+                        None
-                            None
+                    }
+                })
+                .map_or_else(
+                    || {
+                        sess.span_err(attr_segments[1].ident.span, "Usage of unknown attribute");
+                        false
+                    },
+                    |deprecation_status| {
+                        let mut diag =
+                            sess.struct_span_err(attr_segments[1].ident.span, "Usage of deprecated attribute");
+                        match *deprecation_status {
+                            DeprecationStatus::Deprecated => {
+                                diag.emit();
+                                false
+                            },
+                            DeprecationStatus::Replaced(new_name) => {
+                                diag.span_suggestion(
+                                    attr_segments[1].ident.span,
+                                    "consider using",
+                                    new_name.to_string(),
+                                    Applicability::MachineApplicable,
+                                );
+                                diag.emit();
+                                false
+                            },
+                            DeprecationStatus::None => {
+                                diag.cancel();
+                                attr_segments[1].ident.to_string() == name
+                            },
                         }
-                    })
-            {
-                let mut diag = sess.struct_span_err(attr_segments[1].ident.span, "Usage of deprecated attribute");
-                match *deprecation_status {
-                    DeprecationStatus::Deprecated => {
-                        diag.emit();
-                        false
                     },
-                    DeprecationStatus::Replaced(new_name) => {
+                )
-                        diag.span_suggestion(
-                            attr_segments[1].ident.span,
-                            "consider using",
-                            new_name.to_string(),
-                            Applicability::MachineApplicable,
-                        );
-                        diag.emit();
-                        false
-                    },
-                    DeprecationStatus::None => {
-                        diag.cancel();
-                        attr_segments[1].ident.to_string() == name
-                    },
-                }
-            } else {
-                sess.span_err(attr_segments[1].ident.span, "Usage of unknown attribute");
-                false
-            }
         } else {
             false
         }

clippy_lints/src/utils/conf.rs

@@ -156,6 +156,8 @@ define_Conf! {
     (array_size_threshold, "array_size_threshold": u64, 512_000),
     /// Lint: VEC_BOX. The size of the boxed type in bytes, where boxing in a `Vec` is allowed
     (vec_box_size_threshold, "vec_box_size_threshold": u64, 4096),
+    /// Lint: TYPE_REPETITION_IN_BOUNDS. The maximum number of bounds a trait can have to be linted
+    (max_trait_bounds, "max_trait_bounds": u64, 3),
     /// Lint: STRUCT_EXCESSIVE_BOOLS. The maximum number of bools a struct can have
     (max_struct_bools, "max_struct_bools": u64, 3),
     /// Lint: FN_PARAMS_EXCESSIVE_BOOLS. The maximum number of bools function parameters can have

clippy_lints/src/utils/hir_utils.rs

@@ -703,6 +703,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                     }
                     for segment in path.segments {
                         segment.ident.name.hash(&mut self.s);
+                        self.hash_generic_args(segment.generic_args().args);
                     }
                 },
                 QPath::TypeRelative(ref ty, ref segment) => {
@@ -711,13 +712,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 },
             },
             TyKind::OpaqueDef(_, arg_list) => {
-                for arg in *arg_list {
+                self.hash_generic_args(arg_list);
-                    match arg {
-                        GenericArg::Lifetime(ref l) => self.hash_lifetime(l),
-                        GenericArg::Type(ref ty) => self.hash_ty(&ty),
-                        GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
-                    }
-                }
             },
             TyKind::TraitObject(_, lifetime) => {
                 self.hash_lifetime(lifetime);
@@ -735,4 +730,14 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         self.hash_expr(&self.cx.tcx.hir().body(body_id).value);
         self.maybe_typeck_tables = old_maybe_typeck_tables;
     }
+
+    fn hash_generic_args(&mut self, arg_list: &[GenericArg<'_>]) {
+        for arg in arg_list {
+            match arg {
+                GenericArg::Lifetime(ref l) => self.hash_lifetime(l),
+                GenericArg::Type(ref ty) => self.hash_ty(&ty),
+                GenericArg::Const(ref ca) => self.hash_body(ca.value.body),
+            }
+        }
+    }
 }

clippy_lints/src/utils/mod.rs

@@ -102,11 +102,7 @@ pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
 #[must_use]
 pub fn in_macro(span: Span) -> bool {
     if span.from_expansion() {
-        if let ExpnKind::Desugaring(..) = span.ctxt().outer_expn_data().kind {
+        !matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Desugaring(..))
-            false
-        } else {
-            true
-        }
     } else {
         false
     }
@@ -127,10 +123,7 @@ pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
 
 /// Checks if given pattern is a wildcard (`_`)
 pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
-    match pat.kind {
+    matches!(pat.kind, PatKind::Wild)
-        PatKind::Wild => true,
-        _ => false,
-    }
 }
 
 /// Checks if type is struct, enum or union type with the given def path.
@@ -153,11 +146,7 @@ pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symb
 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
     let def_id = cx.tables().type_dependent_def_id(expr.hir_id).unwrap();
     let trt_id = cx.tcx.trait_of_item(def_id);
-    if let Some(trt_id) = trt_id {
+    trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path))
-        match_def_path(cx, trt_id, path)
-    } else {
-        false
-    }
 }
 
 /// Checks if an expression references a variable of the given name.
@@ -600,21 +589,15 @@ pub fn snippet_block_with_applicability<'a, T: LintContext>(
 /// //  ^^^^^^^^^^
 /// ```
 pub fn first_line_of_span<T: LintContext>(cx: &T, span: Span) -> Span {
-    if let Some(first_char_pos) = first_char_in_first_line(cx, span) {
+    first_char_in_first_line(cx, span).map_or(span, |first_char_pos| span.with_lo(first_char_pos))
-        span.with_lo(first_char_pos)
-    } else {
-        span
-    }
 }
 
 fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePos> {
     let line_span = line_span(cx, span);
-    if let Some(snip) = snippet_opt(cx, line_span) {
+    snippet_opt(cx, line_span).and_then(|snip| {
         snip.find(|c: char| !c.is_whitespace())
             .map(|pos| line_span.lo() + BytePos::from_usize(pos))
-    } else {
+    })
-        None
-    }
 }
 
 /// Returns the indentation of the line of a span
@@ -626,11 +609,7 @@ fn first_char_in_first_line<T: LintContext>(cx: &T, span: Span) -> Option<BytePo
 /// //          ^^ -- will return 4
 /// ```
 pub fn indent_of<T: LintContext>(cx: &T, span: Span) -> Option<usize> {
-    if let Some(snip) = snippet_opt(cx, line_span(cx, span)) {
+    snippet_opt(cx, line_span(cx, span)).and_then(|snip| snip.find(|c: char| !c.is_whitespace()))
-        snip.find(|c: char| !c.is_whitespace())
-    } else {
-        None
-    }
 }
 
 /// Extends the span to the beginning of the spans line, incl. whitespaces.
@@ -738,25 +717,21 @@ pub fn get_enclosing_block<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Optio
     let enclosing_node = map
         .get_enclosing_scope(hir_id)
         .and_then(|enclosing_id| map.find(enclosing_id));
-    if let Some(node) = enclosing_node {
+    enclosing_node.and_then(|node| match node {
-        match node {
+        Node::Block(block) => Some(block),
-            Node::Block(block) => Some(block),
+        Node::Item(&Item {
-            Node::Item(&Item {
+            kind: ItemKind::Fn(_, _, eid),
-                kind: ItemKind::Fn(_, _, eid),
+            ..
-                ..
+        })
-            })
+        | Node::ImplItem(&ImplItem {
-            | Node::ImplItem(&ImplItem {
+            kind: ImplItemKind::Fn(_, eid),
-                kind: ImplItemKind::Fn(_, eid),
+            ..
-                ..
+        }) => match cx.tcx.hir().body(eid).value.kind {
-            }) => match cx.tcx.hir().body(eid).value.kind {
+            ExprKind::Block(ref block, _) => Some(block),
-                ExprKind::Block(ref block, _) => Some(block),
-                _ => None,
-            },
             _ => None,
-        }
+        },
-    } else {
+        _ => None,
-        None
+    })
-    }
 }
 
 /// Returns the base type for HIR references and pointers.
@@ -1328,11 +1303,7 @@ pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         _ => None,
     };
 
-    if let Some(did) = did {
+    did.map_or(false, |did| must_use_attr(&cx.tcx.get_attrs(did)).is_some())
-        must_use_attr(&cx.tcx.get_attrs(did)).is_some()
-    } else {
-        false
-    }
 }
 
 pub fn is_no_std_crate(krate: &Crate<'_>) -> bool {
@@ -1385,6 +1356,21 @@ pub fn fn_has_unsatisfiable_preds(cx: &LateContext<'_>, did: DefId) -> bool {
     )
 }
 
+/// Returns the `DefId` of the callee if the given expression is a function or method call.
+pub fn fn_def_id(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<DefId> {
+    match &expr.kind {
+        ExprKind::MethodCall(..) => cx.tables().type_dependent_def_id(expr.hir_id),
+        ExprKind::Call(
+            Expr {
+                kind: ExprKind::Path(qpath),
+                ..
+            },
+            ..,
+        ) => cx.tables().qpath_res(qpath, expr.hir_id).opt_def_id(),
+        _ => None,
+    }
+}
+
 pub fn run_lints(cx: &LateContext<'_>, lints: &[&'static Lint], id: HirId) -> bool {
     lints.iter().any(|lint| {
         matches!(

clippy_lints/src/utils/numeric_literal.rs

@@ -51,7 +51,7 @@ 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 (unsuffixed, suffix) = split_suffix(&src, lit_kind);
-            let float = if let LitKind::Float(..) = lit_kind { true } else { false };
+            let float = matches!(lit_kind, LitKind::Float(..));
             Some(NumericLiteral::new(unsuffixed, suffix, float))
         } else {
             None
@@ -200,12 +200,10 @@ impl<'a> NumericLiteral<'a> {
 
 fn split_suffix<'a>(src: &'a str, lit_kind: &LitKind) -> (&'a str, Option<&'a str>) {
     debug_assert!(lit_kind.is_numeric());
-    if let Some(suffix_length) = lit_suffix_length(lit_kind) {
+    lit_suffix_length(lit_kind).map_or((src, None), |suffix_length| {
         let (unsuffixed, suffix) = src.split_at(src.len() - suffix_length);
         (unsuffixed, Some(suffix))
-    } else {
+    })
-        (src, None)
-    }
 }
 
 fn lit_suffix_length(lit_kind: &LitKind) -> Option<usize> {

clippy_lints/src/utils/paths.rs

@@ -98,7 +98,6 @@ pub const RANGE_TO_STD: [&str; 3] = ["std", "ops", "RangeTo"];
 pub const RC: [&str; 3] = ["alloc", "rc", "Rc"];
 pub const RC_PTR_EQ: [&str; 4] = ["alloc", "rc", "Rc", "ptr_eq"];
 pub const RECEIVER: [&str; 4] = ["std", "sync", "mpsc", "Receiver"];
-pub const REGEX: [&str; 3] = ["regex", "re_unicode", "Regex"];
 pub const REGEX_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "unicode", "RegexBuilder", "new"];
 pub const REGEX_BYTES_BUILDER_NEW: [&str; 5] = ["regex", "re_builder", "bytes", "RegexBuilder", "new"];
 pub const REGEX_BYTES_NEW: [&str; 4] = ["regex", "re_bytes", "Regex", "new"];

clippy_lints/src/utils/sugg.rs

@@ -325,22 +325,22 @@ pub fn make_unop(op: &str, expr: Sugg<'_>) -> Sugg<'static> {
 /// parenthesis will always be added for a mix of these.
 pub fn make_assoc(op: AssocOp, lhs: &Sugg<'_>, rhs: &Sugg<'_>) -> Sugg<'static> {
     /// Returns `true` if the operator is a shift operator `<<` or `>>`.
-    fn is_shift(op: &AssocOp) -> bool {
+    fn is_shift(op: AssocOp) -> bool {
-        matches!(*op, AssocOp::ShiftLeft | AssocOp::ShiftRight)
+        matches!(op, AssocOp::ShiftLeft | AssocOp::ShiftRight)
     }
 
     /// Returns `true` if the operator is a arithmetic operator
     /// (i.e., `+`, `-`, `*`, `/`, `%`).
-    fn is_arith(op: &AssocOp) -> bool {
+    fn is_arith(op: AssocOp) -> bool {
         matches!(
-            *op,
+            op,
             AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide | AssocOp::Modulus
         )
     }
 
     /// Returns `true` if the operator `op` needs parenthesis with the operator
     /// `other` in the direction `dir`.
-    fn needs_paren(op: &AssocOp, other: &AssocOp, dir: Associativity) -> bool {
+    fn needs_paren(op: AssocOp, other: AssocOp, dir: Associativity) -> bool {
         other.precedence() < op.precedence()
             || (other.precedence() == op.precedence()
                 && ((op != other && associativity(op) != dir)
@@ -349,14 +349,14 @@ pub fn make_assoc(op: AssocOp, lhs: &Sugg<'_>, rhs: &Sugg<'_>) -> Sugg<'static>
             || is_shift(other) && is_arith(op)
     }
 
-    let lhs_paren = if let Sugg::BinOp(ref lop, _) = *lhs {
+    let lhs_paren = if let Sugg::BinOp(lop, _) = *lhs {
-        needs_paren(&op, lop, Associativity::Left)
+        needs_paren(op, lop, Associativity::Left)
     } else {
         false
     };
 
-    let rhs_paren = if let Sugg::BinOp(ref rop, _) = *rhs {
+    let rhs_paren = if let Sugg::BinOp(rop, _) = *rhs {
-        needs_paren(&op, rop, Associativity::Right)
+        needs_paren(op, rop, Associativity::Right)
     } else {
         false
     };
@@ -424,13 +424,13 @@ enum Associativity {
 /// they are considered
 /// associative.
 #[must_use]
-fn associativity(op: &AssocOp) -> Associativity {
+fn associativity(op: AssocOp) -> Associativity {
     use rustc_ast::util::parser::AssocOp::{
         Add, As, Assign, AssignOp, BitAnd, BitOr, BitXor, Colon, Divide, DotDot, DotDotEq, Equal, Greater,
         GreaterEqual, LAnd, LOr, Less, LessEqual, Modulus, Multiply, NotEqual, ShiftLeft, ShiftRight, Subtract,
     };
 
-    match *op {
+    match op {
         Assign | AssignOp(_) => Associativity::Right,
         Add | BitAnd | BitOr | BitXor | LAnd | LOr | Multiply | As | Colon => Associativity::Both,
         Divide | Equal | Greater | GreaterEqual | Less | LessEqual | Modulus | NotEqual | ShiftLeft | ShiftRight
@@ -492,20 +492,20 @@ fn astbinop2assignop(op: ast::BinOp) -> AssocOp {
 /// before it on its line.
 fn indentation<T: LintContext>(cx: &T, span: Span) -> Option<String> {
     let lo = cx.sess().source_map().lookup_char_pos(span.lo());
-    if let Some(line) = lo.file.get_line(lo.line - 1 /* line numbers in `Loc` are 1-based */) {
+    lo.file
-        if let Some((pos, _)) = line.char_indices().find(|&(_, c)| c != ' ' && c != '\t') {
+        .get_line(lo.line - 1 /* line numbers in `Loc` are 1-based */)
-            // We can mix char and byte positions here because we only consider `[ \t]`.
+        .and_then(|line| {
-            if lo.col == CharPos(pos) {
+            if let Some((pos, _)) = line.char_indices().find(|&(_, c)| c != ' ' && c != '\t') {
-                Some(line[..pos].into())
+                // We can mix char and byte positions here because we only consider `[ \t]`.
+                if lo.col == CharPos(pos) {
+                    Some(line[..pos].into())
+                } else {
+                    None
+                }
             } else {
                 None
             }
-        } else {
+        })
-            None
-        }
-    } else {
-        None
-    }
 }
 
 /// Convenience extension trait for `DiagnosticBuilder`.

clippy_lints/src/write.rs

@@ -23,7 +23,11 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```rust
+    /// // Bad
     /// println!("");
+    ///
+    /// // Good
+    /// println!();
     /// ```
     pub PRINTLN_EMPTY_STRING,
     style,
@@ -32,8 +36,7 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// **What it does:** This lint warns when you use `print!()` with a format
-    /// string that
+    /// string that ends in a newline.
-    /// ends in a newline.
     ///
     /// **Why is this bad?** You should use `println!()` instead, which appends the
     /// newline.
@@ -125,7 +128,12 @@ declare_clippy_lint! {
     /// ```rust
     /// # use std::fmt::Write;
     /// # let mut buf = String::new();
+    ///
+    /// // Bad
     /// writeln!(buf, "");
+    ///
+    /// // Good
+    /// writeln!(buf);
     /// ```
     pub WRITELN_EMPTY_STRING,
     style,
@@ -147,7 +155,12 @@ declare_clippy_lint! {
     /// # use std::fmt::Write;
     /// # let mut buf = String::new();
     /// # let name = "World";
+    ///
+    /// // Bad
     /// write!(buf, "Hello {}!\n", name);
+    ///
+    /// // Good
+    /// writeln!(buf, "Hello {}!", name);
     /// ```
     pub WRITE_WITH_NEWLINE,
     style,
@@ -168,7 +181,12 @@ declare_clippy_lint! {
     /// ```rust
     /// # use std::fmt::Write;
     /// # let mut buf = String::new();
+    ///
+    /// // Bad
     /// writeln!(buf, "{}", "foo");
+    ///
+    /// // Good
+    /// writeln!(buf, "foo");
     /// ```
     pub WRITE_LITERAL,
     style,
@@ -279,13 +297,13 @@ impl EarlyLintPass for Write {
             if let (Some(fmt_str), expr) = self.check_tts(cx, &mac.args.inner_tokens(), true) {
                 if fmt_str.symbol == Symbol::intern("") {
                     let mut applicability = Applicability::MachineApplicable;
-                    let suggestion = match expr {
+                    let suggestion = expr.map_or_else(
-                        Some(expr) => snippet_with_applicability(cx, expr.span, "v", &mut applicability),
+                        || {
-                        None => {
                             applicability = Applicability::HasPlaceholders;
                             Cow::Borrowed("v")
                         },
-                    };
+                        |e| snippet_with_applicability(cx, e.span, "v", &mut Applicability::MachineApplicable),
+                    );
 
                     span_lint_and_sugg(
                         cx,

src/driver.rs

@@ -382,13 +382,8 @@ pub fn main() {
 
         let should_describe_lints = || {
             let args: Vec<_> = env::args().collect();
-            args.windows(2).any(|args| {
+            args.windows(2)
-                args[1] == "help"
+                .any(|args| args[1] == "help" && matches!(args[0].as_str(), "-W" | "-A" | "-D" | "-F"))
-                    && match args[0].as_str() {
-                        "-W" | "-A" | "-D" | "-F" => true,
-                        _ => false,
-                    }
-            })
         };
 
         if !wrapper_mode && should_describe_lints() {

src/lintlist/mod.rs

@@ -80,6 +80,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "blacklisted_name",
     },
+    Lint {
+        name: "blanket_clippy_restriction_lints",
+        group: "style",
+        desc: "enabling the complete restriction group",
+        deprecation: None,
+        module: "attrs",
+    },
     Lint {
         name: "blocks_in_if_conditions",
         group: "style",
@@ -1144,6 +1151,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "methods",
     },
+    Lint {
+        name: "map_identity",
+        group: "complexity",
+        desc: "using iterator.map(|x| x)",
+        deprecation: None,
+        module: "map_identity",
+    },
     Lint {
         name: "map_unwrap_or",
         group: "pedantic",
@@ -1165,6 +1179,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "matches",
     },
+    Lint {
+        name: "match_like_matches_macro",
+        group: "style",
+        desc: "a match that could be written with the matches! macro",
+        deprecation: None,
+        module: "matches",
+    },
     Lint {
         name: "match_on_vec_items",
         group: "pedantic",
@@ -1606,6 +1627,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "option_env_unwrap",
     },
+    Lint {
+        name: "option_if_let_else",
+        group: "pedantic",
+        desc: "reimplementation of Option::map_or",
+        deprecation: None,
+        module: "option_if_let_else",
+    },
     Lint {
         name: "option_map_or_none",
         group: "style",
@@ -1683,6 +1711,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "path_buf_push_overwrite",
     },
+    Lint {
+        name: "pattern_type_mismatch",
+        group: "restriction",
+        desc: "type of pattern does not match the expression type",
+        deprecation: None,
+        module: "pattern_type_mismatch",
+    },
     Lint {
         name: "possible_missing_comma",
         group: "correctness",
@@ -1755,7 +1790,7 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
     },
     Lint {
         name: "range_minus_one",
-        group: "complexity",
+        group: "pedantic",
         desc: "`x..=(y-1)` reads better as `x..y`",
         deprecation: None,
         module: "ranges",
@@ -1828,7 +1863,7 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         group: "style",
         desc: "use the proper utility function avoiding an `if let`",
         deprecation: None,
-        module: "redundant_pattern_matching",
+        module: "matches",
     },
     Lint {
         name: "redundant_pub_crate",
@@ -1852,11 +1887,11 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         module: "reference",
     },
     Lint {
-        name: "regex_macro",
+        name: "repeat_once",
-        group: "style",
+        group: "complexity",
-        desc: "use of `regex!(_)` instead of `Regex::new(_)`",
+        desc: "using `.repeat(1)` instead of `String.clone()`, `str.to_string()` or `slice.to_vec()` ",
         deprecation: None,
-        module: "regex",
+        module: "repeat_once",
     },
     Lint {
         name: "rest_pat_in_fully_bound_structs",

tests/compile-test.rs

@@ -12,19 +12,11 @@ use std::path::{Path, PathBuf};
 mod cargo;
 
 fn host_lib() -> PathBuf {
-    if let Some(path) = option_env!("HOST_LIBS") {
+    option_env!("HOST_LIBS").map_or(cargo::CARGO_TARGET_DIR.join(env!("PROFILE")), PathBuf::from)
-        PathBuf::from(path)
-    } else {
-        cargo::CARGO_TARGET_DIR.join(env!("PROFILE"))
-    }
 }
 
 fn clippy_driver_path() -> PathBuf {
-    if let Some(path) = option_env!("CLIPPY_DRIVER_PATH") {
+    option_env!("CLIPPY_DRIVER_PATH").map_or(cargo::TARGET_LIB.join("clippy-driver"), PathBuf::from)
-        PathBuf::from(path)
-    } else {
-        cargo::TARGET_LIB.join("clippy-driver")
-    }
 }
 
 // When we'll want to use `extern crate ..` for a dependency that is used

tests/ui-cargo/multiple_crate_versions/fail/Cargo.lock

@@ -0,0 +1,109 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "ansi_term"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
+dependencies = [
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "bitflags"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4efd02e230a02e18f92fc2735f44597385ed02ad8f831e7c1c1156ee5e1ab3a5"
+
+[[package]]
+name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
+[[package]]
+name = "ctrlc"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "653abc99aa905f693d89df4797fadc08085baee379db92be9f2496cefe8a6f2c"
+dependencies = [
+ "kernel32-sys",
+ "nix",
+ "winapi 0.2.8",
+]
+
+[[package]]
+name = "kernel32-sys"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
+dependencies = [
+ "winapi 0.2.8",
+ "winapi-build",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.71"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9457b06509d27052635f90d6466700c65095fdf75409b3fbdd903e988b886f49"
+
+[[package]]
+name = "multiple_crate_versions"
+version = "0.1.0"
+dependencies = [
+ "ansi_term",
+ "ctrlc",
+]
+
+[[package]]
+name = "nix"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2c5afeb0198ec7be8569d666644b574345aad2e95a53baf3a532da3e0f3fb32"
+dependencies = [
+ "bitflags",
+ "cfg-if",
+ "libc",
+ "void",
+]
+
+[[package]]
+name = "void"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
+
+[[package]]
+name = "winapi"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-build"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d315eee3b34aca4797b2da6b13ed88266e6d612562a0c46390af8299fc699bc"
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"

tests/ui-cargo/multiple_crate_versions/fail/src/main.stderr

@@ -1,4 +1,4 @@
-error: multiple versions for dependency `winapi`: 0.2.8, 0.3.8
+error: multiple versions for dependency `winapi`: 0.2.8, 0.3.9
    |
    = note: `-D clippy::multiple-crate-versions` implied by `-D warnings`
 

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -1,4 +1,4 @@
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `third-party` at line 5 column 1
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `third-party` at line 5 column 1
 
 error: aborting due to previous error
 

tests/ui/attrs.rs

@@ -1,5 +1,11 @@
 #![warn(clippy::inline_always, clippy::deprecated_semver)]
 #![allow(clippy::assertions_on_constants)]
+// Test that the whole restriction group is not enabled
+#![warn(clippy::restriction)]
+#![deny(clippy::restriction)]
+#![forbid(clippy::restriction)]
+#![allow(clippy::missing_docs_in_private_items, clippy::panic, clippy::unreachable)]
+
 #[inline(always)]
 fn test_attr_lint() {
     assert!(true)

tests/ui/attrs.stderr

@@ -1,5 +1,5 @@
 error: you have declared `#[inline(always)]` on `test_attr_lint`. This is usually a bad idea
-  --> $DIR/attrs.rs:3:1
+  --> $DIR/attrs.rs:9:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | #[inline(always)]
    = note: `-D clippy::inline-always` implied by `-D warnings`
 
 error: the since field must contain a semver-compliant version
-  --> $DIR/attrs.rs:23:14
+  --> $DIR/attrs.rs:29:14
    |
 LL | #[deprecated(since = "forever")]
    |              ^^^^^^^^^^^^^^^^^
@@ -15,10 +15,35 @@ LL | #[deprecated(since = "forever")]
    = note: `-D clippy::deprecated-semver` implied by `-D warnings`
 
 error: the since field must contain a semver-compliant version
-  --> $DIR/attrs.rs:26:14
+  --> $DIR/attrs.rs:32:14
    |
 LL | #[deprecated(since = "1")]
    |              ^^^^^^^^^^^
 
-error: aborting due to 3 previous errors
+error: restriction lints are not meant to be all enabled
+  --> $DIR/attrs.rs:4:9
+   |
+LL | #![warn(clippy::restriction)]
+   |         ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::blanket-clippy-restriction-lints` implied by `-D warnings`
+   = help: try enabling only the lints you really need
+
+error: restriction lints are not meant to be all enabled
+  --> $DIR/attrs.rs:5:9
+   |
+LL | #![deny(clippy::restriction)]
+   |         ^^^^^^^^^^^^^^^^^^^
+   |
+   = help: try enabling only the lints you really need
+
+error: restriction lints are not meant to be all enabled
+  --> $DIR/attrs.rs:6:11
+   |
+LL | #![forbid(clippy::restriction)]
+   |           ^^^^^^^^^^^^^^^^^^^
+   |
+   = help: try enabling only the lints you really need
+
+error: aborting due to 6 previous errors
 

tests/ui/clone_on_copy.fixed

@@ -0,0 +1,40 @@
+// run-rustfix
+
+#![allow(
+    unused,
+    clippy::redundant_clone,
+    clippy::deref_addrof,
+    clippy::no_effect,
+    clippy::unnecessary_operation
+)]
+
+use std::cell::RefCell;
+use std::rc::{self, Rc};
+use std::sync::{self, Arc};
+
+fn main() {}
+
+fn is_ascii(ch: char) -> bool {
+    ch.is_ascii()
+}
+
+fn clone_on_copy() {
+    42;
+
+    vec![1].clone(); // ok, not a Copy type
+    Some(vec![1]).clone(); // ok, not a Copy type
+    *(&42);
+
+    let rc = RefCell::new(0);
+    *rc.borrow();
+
+    // Issue #4348
+    let mut x = 43;
+    let _ = &x.clone(); // ok, getting a ref
+    'a'.clone().make_ascii_uppercase(); // ok, clone and then mutate
+    is_ascii('z');
+
+    // Issue #5436
+    let mut vec = Vec::new();
+    vec.push(42);
+}

tests/ui/clone_on_copy.rs

@@ -0,0 +1,40 @@
+// run-rustfix
+
+#![allow(
+    unused,
+    clippy::redundant_clone,
+    clippy::deref_addrof,
+    clippy::no_effect,
+    clippy::unnecessary_operation
+)]
+
+use std::cell::RefCell;
+use std::rc::{self, Rc};
+use std::sync::{self, Arc};
+
+fn main() {}
+
+fn is_ascii(ch: char) -> bool {
+    ch.is_ascii()
+}
+
+fn clone_on_copy() {
+    42.clone();
+
+    vec![1].clone(); // ok, not a Copy type
+    Some(vec![1]).clone(); // ok, not a Copy type
+    (&42).clone();
+
+    let rc = RefCell::new(0);
+    rc.borrow().clone();
+
+    // Issue #4348
+    let mut x = 43;
+    let _ = &x.clone(); // ok, getting a ref
+    'a'.clone().make_ascii_uppercase(); // ok, clone and then mutate
+    is_ascii('z'.clone());
+
+    // Issue #5436
+    let mut vec = Vec::new();
+    vec.push(42.clone());
+}

tests/ui/clone_on_copy.stderr

@@ -0,0 +1,34 @@
+error: using `clone` on a `Copy` type
+  --> $DIR/clone_on_copy.rs:22:5
+   |
+LL |     42.clone();
+   |     ^^^^^^^^^^ help: try removing the `clone` call: `42`
+   |
+   = note: `-D clippy::clone-on-copy` implied by `-D warnings`
+
+error: using `clone` on a `Copy` type
+  --> $DIR/clone_on_copy.rs:26:5
+   |
+LL |     (&42).clone();
+   |     ^^^^^^^^^^^^^ help: try dereferencing it: `*(&42)`
+
+error: using `clone` on a `Copy` type
+  --> $DIR/clone_on_copy.rs:29:5
+   |
+LL |     rc.borrow().clone();
+   |     ^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*rc.borrow()`
+
+error: using `clone` on a `Copy` type
+  --> $DIR/clone_on_copy.rs:35:14
+   |
+LL |     is_ascii('z'.clone());
+   |              ^^^^^^^^^^^ help: try removing the `clone` call: `'z'`
+
+error: using `clone` on a `Copy` type
+  --> $DIR/clone_on_copy.rs:39:14
+   |
+LL |     vec.push(42.clone());
+   |              ^^^^^^^^^^ help: try removing the `clone` call: `42`
+
+error: aborting due to 5 previous errors
+

tests/ui/cmp_owned/asymmetric_partial_eq.fixed

@@ -0,0 +1,93 @@
+// run-rustfix
+#![allow(unused, clippy::redundant_clone)] // See #5700
+
+// Define the types in each module to avoid trait impls leaking between modules.
+macro_rules! impl_types {
+    () => {
+        #[derive(PartialEq)]
+        pub struct Owned;
+
+        pub struct Borrowed;
+
+        impl ToOwned for Borrowed {
+            type Owned = Owned;
+            fn to_owned(&self) -> Owned {
+                Owned {}
+            }
+        }
+
+        impl std::borrow::Borrow<Borrowed> for Owned {
+            fn borrow(&self) -> &Borrowed {
+                static VALUE: Borrowed = Borrowed {};
+                &VALUE
+            }
+        }
+    };
+}
+
+// Only Borrowed == Owned is implemented
+mod borrowed_eq_owned {
+    impl_types!();
+
+    impl PartialEq<Owned> for Borrowed {
+        fn eq(&self, _: &Owned) -> bool {
+            true
+        }
+    }
+
+    pub fn compare() {
+        let owned = Owned {};
+        let borrowed = Borrowed {};
+
+        if borrowed == owned {}
+        if borrowed == owned {}
+    }
+}
+
+// Only Owned == Borrowed is implemented
+mod owned_eq_borrowed {
+    impl_types!();
+
+    impl PartialEq<Borrowed> for Owned {
+        fn eq(&self, _: &Borrowed) -> bool {
+            true
+        }
+    }
+
+    fn compare() {
+        let owned = Owned {};
+        let borrowed = Borrowed {};
+
+        if owned == borrowed {}
+        if owned == borrowed {}
+    }
+}
+
+mod issue_4874 {
+    impl_types!();
+
+    // NOTE: PartialEq<Borrowed> for T can't be implemented due to the orphan rules
+    impl<T> PartialEq<T> for Borrowed
+    where
+        T: AsRef<str> + ?Sized,
+    {
+        fn eq(&self, _: &T) -> bool {
+            true
+        }
+    }
+
+    impl std::fmt::Display for Borrowed {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "borrowed")
+        }
+    }
+
+    fn compare() {
+        let borrowed = Borrowed {};
+
+        if borrowed == "Hi" {}
+        if borrowed == "Hi" {}
+    }
+}
+
+fn main() {}

tests/ui/cmp_owned/asymmetric_partial_eq.rs

@@ -0,0 +1,93 @@
+// run-rustfix
+#![allow(unused, clippy::redundant_clone)] // See #5700
+
+// Define the types in each module to avoid trait impls leaking between modules.
+macro_rules! impl_types {
+    () => {
+        #[derive(PartialEq)]
+        pub struct Owned;
+
+        pub struct Borrowed;
+
+        impl ToOwned for Borrowed {
+            type Owned = Owned;
+            fn to_owned(&self) -> Owned {
+                Owned {}
+            }
+        }
+
+        impl std::borrow::Borrow<Borrowed> for Owned {
+            fn borrow(&self) -> &Borrowed {
+                static VALUE: Borrowed = Borrowed {};
+                &VALUE
+            }
+        }
+    };
+}
+
+// Only Borrowed == Owned is implemented
+mod borrowed_eq_owned {
+    impl_types!();
+
+    impl PartialEq<Owned> for Borrowed {
+        fn eq(&self, _: &Owned) -> bool {
+            true
+        }
+    }
+
+    pub fn compare() {
+        let owned = Owned {};
+        let borrowed = Borrowed {};
+
+        if borrowed.to_owned() == owned {}
+        if owned == borrowed.to_owned() {}
+    }
+}
+
+// Only Owned == Borrowed is implemented
+mod owned_eq_borrowed {
+    impl_types!();
+
+    impl PartialEq<Borrowed> for Owned {
+        fn eq(&self, _: &Borrowed) -> bool {
+            true
+        }
+    }
+
+    fn compare() {
+        let owned = Owned {};
+        let borrowed = Borrowed {};
+
+        if owned == borrowed.to_owned() {}
+        if borrowed.to_owned() == owned {}
+    }
+}
+
+mod issue_4874 {
+    impl_types!();
+
+    // NOTE: PartialEq<Borrowed> for T can't be implemented due to the orphan rules
+    impl<T> PartialEq<T> for Borrowed
+    where
+        T: AsRef<str> + ?Sized,
+    {
+        fn eq(&self, _: &T) -> bool {
+            true
+        }
+    }
+
+    impl std::fmt::Display for Borrowed {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "borrowed")
+        }
+    }
+
+    fn compare() {
+        let borrowed = Borrowed {};
+
+        if "Hi" == borrowed.to_string() {}
+        if borrowed.to_string() == "Hi" {}
+    }
+}
+
+fn main() {}

tests/ui/cmp_owned/asymmetric_partial_eq.stderr

@@ -0,0 +1,46 @@
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:42:12
+   |
+LL |         if borrowed.to_owned() == owned {}
+   |            ^^^^^^^^^^^^^^^^^^^ help: try: `borrowed`
+   |
+   = note: `-D clippy::cmp-owned` implied by `-D warnings`
+
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:43:21
+   |
+LL |         if owned == borrowed.to_owned() {}
+   |            ---------^^^^^^^^^^^^^^^^^^^
+   |            |
+   |            help: try: `borrowed == owned`
+
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:61:21
+   |
+LL |         if owned == borrowed.to_owned() {}
+   |                     ^^^^^^^^^^^^^^^^^^^ help: try: `borrowed`
+
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:62:12
+   |
+LL |         if borrowed.to_owned() == owned {}
+   |            ^^^^^^^^^^^^^^^^^^^---------
+   |            |
+   |            help: try: `owned == borrowed`
+
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:88:20
+   |
+LL |         if "Hi" == borrowed.to_string() {}
+   |            --------^^^^^^^^^^^^^^^^^^^^
+   |            |
+   |            help: try: `borrowed == "Hi"`
+
+error: this creates an owned instance just for comparison
+  --> $DIR/asymmetric_partial_eq.rs:89:12
+   |
+LL |         if borrowed.to_string() == "Hi" {}
+   |            ^^^^^^^^^^^^^^^^^^^^ help: try: `borrowed`
+
+error: aborting due to 6 previous errors
+

tests/ui/collapsible_else_if.stderr

@@ -10,7 +10,7 @@ LL | |     }
    | |_____^
    |
    = note: `-D clippy::collapsible-if` implied by `-D warnings`
-help: try
+help: collapse nested if block
    |
 LL |     } else if y == "world" {
 LL |         println!("world!")
@@ -28,7 +28,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if let Some(42) = Some(42) {
 LL |         println!("world!")
@@ -48,7 +48,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if y == "world" {
 LL |         println!("world")
@@ -71,7 +71,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if let Some(42) = Some(42) {
 LL |         println!("world")
@@ -94,7 +94,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if let Some(42) = Some(42) {
 LL |         println!("world")
@@ -117,7 +117,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if x == "hello" {
 LL |         println!("world")
@@ -140,7 +140,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     } else if let Some(42) = Some(42) {
 LL |         println!("world")

tests/ui/collapsible_if.stderr

@@ -9,7 +9,7 @@ LL | |     }
    | |_____^
    |
    = note: `-D clippy::collapsible-if` implied by `-D warnings`
-help: try
+help: collapse nested if block
    |
 LL |     if x == "hello" && y == "world" {
 LL |         println!("Hello world!");
@@ -26,7 +26,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if (x == "hello" || x == "world") && (y == "world" || y == "hello") {
 LL |         println!("Hello world!");
@@ -43,7 +43,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if x == "hello" && x == "world" && (y == "world" || y == "hello") {
 LL |         println!("Hello world!");
@@ -60,7 +60,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if (x == "hello" || x == "world") && y == "world" && y == "hello" {
 LL |         println!("Hello world!");
@@ -77,7 +77,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if x == "hello" && x == "world" && y == "world" && y == "hello" {
 LL |         println!("Hello world!");
@@ -94,7 +94,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if 42 == 1337 && 'a' != 'A' {
 LL |         println!("world!")
@@ -111,7 +111,7 @@ LL | |         }
 LL | |     }
    | |_____^
    |
-help: try
+help: collapse nested if block
    |
 LL |     if x == "hello" && y == "world" { // Collapsible
 LL |         println!("Hello world!");

tests/ui/deprecated.rs

@@ -7,5 +7,6 @@
 #[warn(clippy::invalid_ref)]
 #[warn(clippy::into_iter_on_array)]
 #[warn(clippy::unused_label)]
+#[warn(clippy::regex_macro)]
 
 fn main() {}

tests/ui/deprecated.stderr

@@ -54,11 +54,17 @@ error: lint `clippy::unused_label` has been removed: `this lint has been uplifte
 LL | #[warn(clippy::unused_label)]
    |        ^^^^^^^^^^^^^^^^^^^^
 
+error: lint `clippy::regex_macro` has been removed: `the regex! macro has been removed from the regex crate in 2018`
+  --> $DIR/deprecated.rs:10:8
+   |
+LL | #[warn(clippy::regex_macro)]
+   |        ^^^^^^^^^^^^^^^^^^^
+
 error: lint `clippy::str_to_string` has been removed: `using `str::to_string` is common even today and specialization will likely happen soon`
   --> $DIR/deprecated.rs:1:8
    |
 LL | #[warn(clippy::str_to_string)]
    |        ^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 10 previous errors
+error: aborting due to 11 previous errors
 

tests/ui/find_map.rs

@@ -19,6 +19,7 @@ fn main() {
 
     let _: Option<i32> = a.iter().find(|s| s.parse::<i32>().is_ok()).map(|s| s.parse().unwrap());
 
+    #[allow(clippy::match_like_matches_macro)]
     let _: Option<Flavor> = desserts_of_the_week
         .iter()
         .find(|dessert| match *dessert {

tests/ui/find_map.stderr

@@ -8,7 +8,7 @@ LL |     let _: Option<i32> = a.iter().find(|s| s.parse::<i32>().is_ok()).map(|s
    = help: this is more succinctly expressed by calling `.find_map(..)` instead
 
 error: called `find(p).map(q)` on an `Iterator`
-  --> $DIR/find_map.rs:22:29
+  --> $DIR/find_map.rs:23:29
    |
 LL |       let _: Option<Flavor> = desserts_of_the_week
    |  _____________________________^

tests/ui/floating_point_hypot.fixed

@@ -0,0 +1,14 @@
+// run-rustfix
+#![warn(clippy::imprecise_flops)]
+
+fn main() {
+    let x = 3f32;
+    let y = 4f32;
+    let _ = x.hypot(y);
+    let _ = (x + 1f32).hypot(y);
+    let _ = x.hypot(y);
+    // Cases where the lint shouldn't be applied
+    // TODO: linting this adds some complexity, but could be done
+    let _ = x.mul_add(x, y * y).sqrt();
+    let _ = (x * 4f32 + y * y).sqrt();
+}

tests/ui/floating_point_hypot.rs

@@ -0,0 +1,14 @@
+// run-rustfix
+#![warn(clippy::imprecise_flops)]
+
+fn main() {
+    let x = 3f32;
+    let y = 4f32;
+    let _ = (x * x + y * y).sqrt();
+    let _ = ((x + 1f32) * (x + 1f32) + y * y).sqrt();
+    let _ = (x.powi(2) + y.powi(2)).sqrt();
+    // Cases where the lint shouldn't be applied
+    // TODO: linting this adds some complexity, but could be done
+    let _ = x.mul_add(x, y * y).sqrt();
+    let _ = (x * 4f32 + y * y).sqrt();
+}

tests/ui/floating_point_hypot.stderr

@@ -0,0 +1,22 @@
+error: hypotenuse can be computed more accurately
+  --> $DIR/floating_point_hypot.rs:7:13
+   |
+LL |     let _ = (x * x + y * y).sqrt();
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.hypot(y)`
+   |
+   = note: `-D clippy::imprecise-flops` implied by `-D warnings`
+
+error: hypotenuse can be computed more accurately
+  --> $DIR/floating_point_hypot.rs:8:13
+   |
+LL |     let _ = ((x + 1f32) * (x + 1f32) + y * y).sqrt();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(x + 1f32).hypot(y)`
+
+error: hypotenuse can be computed more accurately
+  --> $DIR/floating_point_hypot.rs:9:13
+   |
+LL |     let _ = (x.powi(2) + y.powi(2)).sqrt();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.hypot(y)`
+
+error: aborting due to 3 previous errors
+

tests/ui/floating_point_log.fixed

@@ -25,11 +25,11 @@ fn check_ln1p() {
     let _ = 2.0f32.ln_1p();
     let _ = x.ln_1p();
     let _ = (x / 2.0).ln_1p();
-    let _ = x.powi(2).ln_1p();
+    let _ = x.powi(3).ln_1p();
-    let _ = (x.powi(2) / 2.0).ln_1p();
+    let _ = (x.powi(3) / 2.0).ln_1p();
     let _ = ((std::f32::consts::E - 1.0)).ln_1p();
     let _ = x.ln_1p();
-    let _ = x.powi(2).ln_1p();
+    let _ = x.powi(3).ln_1p();
     let _ = (x + 2.0).ln_1p();
     let _ = (x / 2.0).ln_1p();
     // Cases where the lint shouldn't be applied
@@ -43,9 +43,9 @@ fn check_ln1p() {
     let _ = 2.0f64.ln_1p();
     let _ = x.ln_1p();
     let _ = (x / 2.0).ln_1p();
-    let _ = x.powi(2).ln_1p();
+    let _ = x.powi(3).ln_1p();
     let _ = x.ln_1p();
-    let _ = x.powi(2).ln_1p();
+    let _ = x.powi(3).ln_1p();
     let _ = (x + 2.0).ln_1p();
     let _ = (x / 2.0).ln_1p();
     // Cases where the lint shouldn't be applied

tests/ui/floating_point_log.rs

@@ -25,11 +25,11 @@ fn check_ln1p() {
     let _ = (1f32 + 2.0).ln();
     let _ = (1.0 + x).ln();
     let _ = (1.0 + x / 2.0).ln();
-    let _ = (1.0 + x.powi(2)).ln();
+    let _ = (1.0 + x.powi(3)).ln();
-    let _ = (1.0 + x.powi(2) / 2.0).ln();
+    let _ = (1.0 + x.powi(3) / 2.0).ln();
     let _ = (1.0 + (std::f32::consts::E - 1.0)).ln();
     let _ = (x + 1.0).ln();
-    let _ = (x.powi(2) + 1.0).ln();
+    let _ = (x.powi(3) + 1.0).ln();
     let _ = (x + 2.0 + 1.0).ln();
     let _ = (x / 2.0 + 1.0).ln();
     // Cases where the lint shouldn't be applied
@@ -43,9 +43,9 @@ fn check_ln1p() {
     let _ = (1f64 + 2.0).ln();
     let _ = (1.0 + x).ln();
     let _ = (1.0 + x / 2.0).ln();
-    let _ = (1.0 + x.powi(2)).ln();
+    let _ = (1.0 + x.powi(3)).ln();
     let _ = (x + 1.0).ln();
-    let _ = (x.powi(2) + 1.0).ln();
+    let _ = (x.powi(3) + 1.0).ln();
     let _ = (x + 2.0 + 1.0).ln();
     let _ = (x / 2.0 + 1.0).ln();
     // Cases where the lint shouldn't be applied

tests/ui/floating_point_log.stderr

@@ -77,14 +77,14 @@ LL |     let _ = (1.0 + x / 2.0).ln();
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:28:13
    |
-LL |     let _ = (1.0 + x.powi(2)).ln();
+LL |     let _ = (1.0 + x.powi(3)).ln();
-   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(2).ln_1p()`
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(3).ln_1p()`
 
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:29:13
    |
-LL |     let _ = (1.0 + x.powi(2) / 2.0).ln();
+LL |     let _ = (1.0 + x.powi(3) / 2.0).ln();
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(x.powi(2) / 2.0).ln_1p()`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `(x.powi(3) / 2.0).ln_1p()`
 
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:30:13
@@ -101,8 +101,8 @@ LL |     let _ = (x + 1.0).ln();
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:32:13
    |
-LL |     let _ = (x.powi(2) + 1.0).ln();
+LL |     let _ = (x.powi(3) + 1.0).ln();
-   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(2).ln_1p()`
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(3).ln_1p()`
 
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:33:13
@@ -143,8 +143,8 @@ LL |     let _ = (1.0 + x / 2.0).ln();
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:46:13
    |
-LL |     let _ = (1.0 + x.powi(2)).ln();
+LL |     let _ = (1.0 + x.powi(3)).ln();
-   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(2).ln_1p()`
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(3).ln_1p()`
 
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:47:13
@@ -155,8 +155,8 @@ LL |     let _ = (x + 1.0).ln();
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:48:13
    |
-LL |     let _ = (x.powi(2) + 1.0).ln();
+LL |     let _ = (x.powi(3) + 1.0).ln();
-   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(2).ln_1p()`
+   |             ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.powi(3).ln_1p()`
 
 error: ln(1 + x) can be computed more accurately
   --> $DIR/floating_point_log.rs:49:13

tests/ui/floating_point_logbase.fixed

@@ -0,0 +1,16 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let x = 3f32;
+    let y = 5f32;
+    let _ = x.log(y);
+    let _ = x.log(y);
+    let _ = x.log(y);
+    let _ = x.log(y);
+    // Cases where the lint shouldn't be applied
+    let _ = x.ln() / y.powf(3.2);
+    let _ = x.powf(3.2) / y.powf(3.2);
+    let _ = x.powf(3.2) / y.ln();
+    let _ = x.log(5f32) / y.log(7f32);
+}

tests/ui/floating_point_logbase.rs

@@ -0,0 +1,16 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let x = 3f32;
+    let y = 5f32;
+    let _ = x.ln() / y.ln();
+    let _ = x.log2() / y.log2();
+    let _ = x.log10() / y.log10();
+    let _ = x.log(5f32) / y.log(5f32);
+    // Cases where the lint shouldn't be applied
+    let _ = x.ln() / y.powf(3.2);
+    let _ = x.powf(3.2) / y.powf(3.2);
+    let _ = x.powf(3.2) / y.ln();
+    let _ = x.log(5f32) / y.log(7f32);
+}

tests/ui/floating_point_logbase.stderr

@@ -0,0 +1,28 @@
+error: log base can be expressed more clearly
+  --> $DIR/floating_point_logbase.rs:7:13
+   |
+LL |     let _ = x.ln() / y.ln();
+   |             ^^^^^^^^^^^^^^^ help: consider using: `x.log(y)`
+   |
+   = note: `-D clippy::suboptimal-flops` implied by `-D warnings`
+
+error: log base can be expressed more clearly
+  --> $DIR/floating_point_logbase.rs:8:13
+   |
+LL |     let _ = x.log2() / y.log2();
+   |             ^^^^^^^^^^^^^^^^^^^ help: consider using: `x.log(y)`
+
+error: log base can be expressed more clearly
+  --> $DIR/floating_point_logbase.rs:9:13
+   |
+LL |     let _ = x.log10() / y.log10();
+   |             ^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.log(y)`
+
+error: log base can be expressed more clearly
+  --> $DIR/floating_point_logbase.rs:10:13
+   |
+LL |     let _ = x.log(5f32) / y.log(5f32);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.log(y)`
+
+error: aborting due to 4 previous errors
+

tests/ui/floating_point_mul_add.fixed

@@ -18,4 +18,9 @@ fn main() {
 
     let _ = a.mul_add(b, c).mul_add(a.mul_add(b, c), a.mul_add(b, c)) + c;
     let _ = 1234.567_f64.mul_add(45.67834_f64, 0.0004_f64);
+
+    let _ = a.mul_add(a, b).sqrt();
+
+    // Cases where the lint shouldn't be applied
+    let _ = (a * a + b * b).sqrt();
 }

tests/ui/floating_point_mul_add.rs

@@ -18,4 +18,9 @@ fn main() {
 
     let _ = a.mul_add(b, c) * a.mul_add(b, c) + a.mul_add(b, c) + c;
     let _ = 1234.567_f64 * 45.67834_f64 + 0.0004_f64;
+
+    let _ = (a * a + b).sqrt();
+
+    // Cases where the lint shouldn't be applied
+    let _ = (a * a + b * b).sqrt();
 }

tests/ui/floating_point_mul_add.stderr

@@ -54,5 +54,11 @@ error: multiply and add expressions can be calculated more efficiently and accur
 LL |     let _ = 1234.567_f64 * 45.67834_f64 + 0.0004_f64;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `1234.567_f64.mul_add(45.67834_f64, 0.0004_f64)`
 
-error: aborting due to 9 previous errors
+error: multiply and add expressions can be calculated more efficiently and accurately
+  --> $DIR/floating_point_mul_add.rs:22:13
+   |
+LL |     let _ = (a * a + b).sqrt();
+   |             ^^^^^^^^^^^ help: consider using: `a.mul_add(a, b)`
+
+error: aborting due to 10 previous errors
 

tests/ui/floating_point_powf.fixed

@@ -11,7 +11,7 @@ fn main() {
     let _ = (-3.1f32).exp();
     let _ = x.sqrt();
     let _ = x.cbrt();
-    let _ = x.powi(2);
+    let _ = x.powi(3);
     let _ = x.powi(-2);
     let _ = x.powi(16_777_215);
     let _ = x.powi(-16_777_215);
@@ -30,7 +30,7 @@ fn main() {
     let _ = (-3.1f64).exp();
     let _ = x.sqrt();
     let _ = x.cbrt();
-    let _ = x.powi(2);
+    let _ = x.powi(3);
     let _ = x.powi(-2);
     let _ = x.powi(-2_147_483_648);
     let _ = x.powi(2_147_483_647);

tests/ui/floating_point_powf.rs

@@ -11,7 +11,7 @@ fn main() {
     let _ = std::f32::consts::E.powf(-3.1);
     let _ = x.powf(1.0 / 2.0);
     let _ = x.powf(1.0 / 3.0);
-    let _ = x.powf(2.0);
+    let _ = x.powf(3.0);
     let _ = x.powf(-2.0);
     let _ = x.powf(16_777_215.0);
     let _ = x.powf(-16_777_215.0);
@@ -30,7 +30,7 @@ fn main() {
     let _ = std::f64::consts::E.powf(-3.1);
     let _ = x.powf(1.0 / 2.0);
     let _ = x.powf(1.0 / 3.0);
-    let _ = x.powf(2.0);
+    let _ = x.powf(3.0);
     let _ = x.powf(-2.0);
     let _ = x.powf(-2_147_483_648.0);
     let _ = x.powf(2_147_483_647.0);

tests/ui/floating_point_powf.stderr

@@ -53,8 +53,8 @@ LL |     let _ = x.powf(1.0 / 3.0);
 error: exponentiation with integer powers can be computed more efficiently
   --> $DIR/floating_point_powf.rs:14:13
    |
-LL |     let _ = x.powf(2.0);
+LL |     let _ = x.powf(3.0);
-   |             ^^^^^^^^^^^ help: consider using: `x.powi(2)`
+   |             ^^^^^^^^^^^ help: consider using: `x.powi(3)`
 
 error: exponentiation with integer powers can be computed more efficiently
   --> $DIR/floating_point_powf.rs:15:13
@@ -125,8 +125,8 @@ LL |     let _ = x.powf(1.0 / 3.0);
 error: exponentiation with integer powers can be computed more efficiently
   --> $DIR/floating_point_powf.rs:33:13
    |
-LL |     let _ = x.powf(2.0);
+LL |     let _ = x.powf(3.0);
-   |             ^^^^^^^^^^^ help: consider using: `x.powi(2)`
+   |             ^^^^^^^^^^^ help: consider using: `x.powi(3)`
 
 error: exponentiation with integer powers can be computed more efficiently
   --> $DIR/floating_point_powf.rs:34:13

tests/ui/floating_point_powi.fixed

@@ -0,0 +1,19 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let one = 1;
+    let x = 3f32;
+    let _ = x * x;
+    let _ = x * x;
+
+    let y = 4f32;
+    let _ = x.mul_add(x, y);
+    let _ = y.mul_add(y, x);
+    let _ = x.mul_add(x, y).sqrt();
+    let _ = y.mul_add(y, x).sqrt();
+    // Cases where the lint shouldn't be applied
+    let _ = x.powi(3);
+    let _ = x.powi(one + 1);
+    let _ = (x.powi(2) + y.powi(2)).sqrt();
+}

tests/ui/floating_point_powi.rs

@@ -0,0 +1,19 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let one = 1;
+    let x = 3f32;
+    let _ = x.powi(2);
+    let _ = x.powi(1 + 1);
+
+    let y = 4f32;
+    let _ = x.powi(2) + y;
+    let _ = x + y.powi(2);
+    let _ = (x.powi(2) + y).sqrt();
+    let _ = (x + y.powi(2)).sqrt();
+    // Cases where the lint shouldn't be applied
+    let _ = x.powi(3);
+    let _ = x.powi(one + 1);
+    let _ = (x.powi(2) + y.powi(2)).sqrt();
+}

tests/ui/floating_point_powi.stderr

@@ -0,0 +1,40 @@
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:7:13
+   |
+LL |     let _ = x.powi(2);
+   |             ^^^^^^^^^ help: consider using: `x * x`
+   |
+   = note: `-D clippy::suboptimal-flops` implied by `-D warnings`
+
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:8:13
+   |
+LL |     let _ = x.powi(1 + 1);
+   |             ^^^^^^^^^^^^^ help: consider using: `x * x`
+
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:11:13
+   |
+LL |     let _ = x.powi(2) + y;
+   |             ^^^^^^^^^^^^^ help: consider using: `x.mul_add(x, y)`
+
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:12:13
+   |
+LL |     let _ = x + y.powi(2);
+   |             ^^^^^^^^^^^^^ help: consider using: `y.mul_add(y, x)`
+
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:13:13
+   |
+LL |     let _ = (x.powi(2) + y).sqrt();
+   |             ^^^^^^^^^^^^^^^ help: consider using: `x.mul_add(x, y)`
+
+error: square can be computed more efficiently
+  --> $DIR/floating_point_powi.rs:14:13
+   |
+LL |     let _ = (x + y.powi(2)).sqrt();
+   |             ^^^^^^^^^^^^^^^ help: consider using: `y.mul_add(y, x)`
+
+error: aborting due to 6 previous errors
+

tests/ui/floating_point_rad.fixed

@@ -0,0 +1,13 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let x = 3f32;
+    let _ = x.to_degrees();
+    let _ = x.to_radians();
+    // Cases where the lint shouldn't be applied
+    let _ = x * 90f32 / std::f32::consts::PI;
+    let _ = x * std::f32::consts::PI / 90f32;
+    let _ = x * 180f32 / std::f32::consts::E;
+    let _ = x * std::f32::consts::E / 180f32;
+}

tests/ui/floating_point_rad.rs

@@ -0,0 +1,13 @@
+// run-rustfix
+#![warn(clippy::suboptimal_flops)]
+
+fn main() {
+    let x = 3f32;
+    let _ = x * 180f32 / std::f32::consts::PI;
+    let _ = x * std::f32::consts::PI / 180f32;
+    // Cases where the lint shouldn't be applied
+    let _ = x * 90f32 / std::f32::consts::PI;
+    let _ = x * std::f32::consts::PI / 90f32;
+    let _ = x * 180f32 / std::f32::consts::E;
+    let _ = x * std::f32::consts::E / 180f32;
+}

tests/ui/floating_point_rad.stderr

@@ -0,0 +1,16 @@
+error: conversion to degrees can be done more accurately
+  --> $DIR/floating_point_rad.rs:6:13
+   |
+LL |     let _ = x * 180f32 / std::f32::consts::PI;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.to_degrees()`
+   |
+   = note: `-D clippy::suboptimal-flops` implied by `-D warnings`
+
+error: conversion to radians can be done more accurately
+  --> $DIR/floating_point_rad.rs:7:13
+   |
+LL |     let _ = x * std::f32::consts::PI / 180f32;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `x.to_radians()`
+
+error: aborting due to 2 previous errors
+

tests/ui/map_flatten.fixed

@@ -2,6 +2,7 @@
 
 #![warn(clippy::all, clippy::pedantic)]
 #![allow(clippy::missing_docs_in_private_items)]
+#![allow(clippy::map_identity)]
 
 fn main() {
     let _: Vec<_> = vec![5_i8; 6].into_iter().flat_map(|x| 0..x).collect();