Auto merge of #84008 - Dylan-DPC:rollup-invxvg8, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #80733 (Improve links in inline code in `core::pin`.)
 - #81764 (Stabilize `rustdoc::bare_urls` lint)
 - #81938 (Stabilize `peekable_peek_mut`)
 - #83980 (Fix outdated crate names in compiler docs)
 - #83992 (Merge idents when generating source content)
 - #84001 (Update Clippy)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_ast/src/expand/mod.rs

@@ -1,3 +1,3 @@
-//! Definitions shared by macros / syntax extensions and e.g. librustc_middle.
+//! Definitions shared by macros / syntax extensions and e.g. `rustc_middle`.
 
 pub mod allocator;

compiler/rustc_ast/src/lib.rs

@@ -59,7 +59,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
-/// instead of implementing everything in librustc_middle.
+/// instead of implementing everything in `rustc_middle`.
 pub trait HashStableContext: rustc_span::HashStableContext {
     fn hash_attr(&mut self, _: &ast::Attribute, hasher: &mut StableHasher);
 }

compiler/rustc_ast_lowering/src/lib.rs

@@ -93,7 +93,7 @@ struct LoweringContext<'a, 'hir: 'a> {
 
     /// HACK(Centril): there is a cyclic dependency between the parser and lowering
     /// if we don't have this function pointer. To avoid that dependency so that
-    /// librustc_middle is independent of the parser, we use dynamic dispatch here.
+    /// `rustc_middle` is independent of the parser, we use dynamic dispatch here.
     nt_to_tokenstream: NtToTokenstream,
 
     /// Used to allocate HIR nodes.

compiler/rustc_codegen_cranelift/src/vtable.rs

@@ -1,6 +1,6 @@
 //! Codegen vtables and vtable accesses.
 //!
-//! See librustc_codegen_llvm/meth.rs for reference
+//! See `rustc_codegen_ssa/src/meth.rs` for reference.
 // FIXME dedup this logic between miri, cg_llvm and cg_clif
 
 use crate::prelude::*;

compiler/rustc_data_structures/src/svh.rs

@@ -19,7 +19,7 @@ pub struct Svh {
 impl Svh {
     /// Creates a new `Svh` given the hash. If you actually want to
     /// compute the SVH from some HIR, you want the `calculate_svh`
-    /// function found in `librustc_incremental`.
+    /// function found in `rustc_incremental`.
     pub fn new(hash: u64) -> Svh {
         Svh { hash }
     }

compiler/rustc_feature/src/lib.rs

@@ -1,7 +1,7 @@
 //! # Feature gates
 //!
 //! This crate declares the set of past and present unstable features in the compiler.
-//! Feature gate checking itself is done in `librustc_ast_passes/feature_gate.rs`
+//! Feature gate checking itself is done in `rustc_ast_passes/src/feature_gate.rs`
 //! at the moment.
 //!
 //! Features are enabled in programs via the crate-level attributes of

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -9,7 +9,7 @@ use rustc_span::def_id::{DefPathHash, LocalDefId};
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
-/// instead of implementing everything in librustc_middle.
+/// instead of implementing everything in `rustc_middle`.
 pub trait HashStableContext:
     rustc_ast::HashStableContext + rustc_target::HashStableContext
 {

compiler/rustc_hir/src/weak_lang_items.rs

@@ -18,8 +18,8 @@ pub static WEAK_ITEMS_REFS: SyncLazy<StableMap<Symbol, LangItem>> = SyncLazy::ne
     map
 });
 
-/// The `check_name` argument avoids the need for `librustc_hir` to depend on
-/// `librustc_session`.
+/// The `check_name` argument avoids the need for `rustc_hir` to depend on
+/// `rustc_session`.
 pub fn link_name<'a, F>(check_name: F, attrs: &'a [ast::Attribute]) -> Option<Symbol>
 where
     F: Fn(&'a ast::Attribute, Symbol) -> bool

compiler/rustc_infer/src/lib.rs

@@ -2,7 +2,7 @@
 //!
 //! - **Type inference.** The type inference code can be found in the `infer` module;
 //!   this code handles low-level equality and subtyping operations. The
-//!   type check pass in the compiler is found in the `librustc_typeck` crate.
+//!   type check pass in the compiler is found in the `rustc_typeck` crate.
 //!
 //! For more information about how rustc works, see the [rustc dev guide].
 //!

compiler/rustc_lexer/src/lib.rs

@@ -1,13 +1,13 @@
 //! Low-level Rust lexer.
 //!
-//! The idea with `librustc_lexer` is to make a reusable library,
+//! The idea with `rustc_lexer` is to make a reusable library,
 //! by separating out pure lexing and rustc-specific concerns, like spans,
 //! error reporting, and interning.  So, rustc_lexer operates directly on `&str`,
 //! produces simple tokens which are a pair of type-tag and a bit of original text,
 //! and does not report errors, instead storing them as flags on the token.
 //!
 //! Tokens produced by this lexer are not yet ready for parsing the Rust syntax.
-//! For that see [`librustc_parse::lexer`], which converts this basic token stream
+//! For that see [`rustc_parse::lexer`], which converts this basic token stream
 //! into wide tokens used by actual parser.
 //!
 //! The purpose of this crate is to convert raw sources into a labeled sequence
@@ -17,7 +17,7 @@
 //! The main entity of this crate is the [`TokenKind`] enum which represents common
 //! lexeme types.
 //!
-//! [`librustc_parse::lexer`]: ../rustc_parse/lexer/index.html
+//! [`rustc_parse::lexer`]: ../rustc_parse/lexer/index.html
 // We want to be able to build this crate with a stable compiler, so no
 // `#![feature]` attributes should be added.
 

compiler/rustc_lint/src/builtin.rs

@@ -2280,7 +2280,7 @@ declare_lint! {
 }
 
 declare_lint_pass!(
-    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `librustc_feature/active.rs`.
+    /// Check for used feature gates in `INCOMPLETE_FEATURES` in `rustc_feature/src/active.rs`.
     IncompleteFeatures => [INCOMPLETE_FEATURES]
 );
 

compiler/rustc_lint/src/levels.rs

@@ -464,15 +464,16 @@ impl<'s> LintLevelsBuilder<'s> {
                 // we don't warn about the name change.
                 if let CheckLintNameResult::Warning(_, Some(new_name)) = lint_result {
                     // Ignore any errors or warnings that happen because the new name is inaccurate
-                    if let CheckLintNameResult::Ok(ids) =
-                        store.check_lint_name(&new_name, tool_name)
-                    {
+                    // NOTE: `new_name` already includes the tool name, so we don't have to add it again.
+                    if let CheckLintNameResult::Ok(ids) = store.check_lint_name(&new_name, None) {
                         let src =
                             LintLevelSource::Node(Symbol::intern(&new_name), li.span(), reason);
                         for &id in ids {
                             self.check_gated_lint(id, attr.span);
                             self.insert_spec(&mut specs, id, (level, src));
                         }
+                    } else {
+                        panic!("renamed lint does not exist: {}", new_name);
                     }
                 }
             }

compiler/rustc_middle/src/ich/impls_syntax.rs

@@ -1,5 +1,5 @@
 //! This module contains `HashStable` implementations for various data types
-//! from librustc_ast in no particular order.
+//! from `rustc_ast` in no particular order.
 
 use crate::ich::StableHashingContext;
 

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -46,7 +46,7 @@ static_assert_size!(InterpErrorInfo<'_>, 8);
 /// Packages the kind of error we got from the const code interpreter
 /// up with a Rust-level backtrace of where the error occurred.
 /// Thsese should always be constructed by calling `.into()` on
-/// a `InterpError`. In `librustc_mir::interpret`, we have `throw_err_*`
+/// a `InterpError`. In `rustc_mir::interpret`, we have `throw_err_*`
 /// macros for this.
 #[derive(Debug)]
 pub struct InterpErrorInfo<'tcx>(Box<InterpErrorInfoInner<'tcx>>);

compiler/rustc_middle/src/traits/query.rs

@@ -3,7 +3,7 @@
 //! which makes a canonical query by replacing unbound inference
 //! variables and regions, so that results can be reused more broadly.
 //! The providers for the queries defined here can be found in
-//! `librustc_traits`.
+//! `rustc_traits`.
 
 use crate::ich::StableHashingContext;
 use crate::infer::canonical::{Canonical, QueryResponse};

compiler/rustc_middle/src/ty/fold.rs

@@ -44,7 +44,7 @@ use std::ops::ControlFlow;
 /// This trait is implemented for every type that can be folded.
 /// Basically, every type that has a corresponding method in `TypeFolder`.
 ///
-/// To implement this conveniently, use the derive macro located in librustc_macros.
+/// To implement this conveniently, use the derive macro located in `rustc_macros`.
 pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self;
     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {

compiler/rustc_middle/src/ty/sty.rs

@@ -80,7 +80,7 @@ impl BoundRegionKind {
 /// Defines the kinds of types.
 ///
 /// N.B., if you change this, you'll probably want to change the corresponding
-/// AST structure in `librustc_ast/ast.rs` as well.
+/// AST structure in `rustc_ast/src/ast.rs` as well.
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
 #[derive(HashStable)]
 #[rustc_diagnostic_item = "TyKind"]
@@ -2116,7 +2116,7 @@ impl<'tcx> TyS<'tcx> {
     ///
     /// Note that during type checking, we use an inference variable
     /// to represent the closure kind, because it has not yet been
-    /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
+    /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
     /// is complete, that type variable will be unified.
     pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
         match self.kind() {

compiler/rustc_mir/src/borrow_check/region_infer/graphviz.rs

@@ -1,5 +1,5 @@
 //! This module provides linkage between RegionInferenceContext and
-//! librustc_graphviz traits, specialized to attaching borrowck analysis
+//! `rustc_graphviz` traits, specialized to attaching borrowck analysis
 //! data to rendered labels.
 
 use std::borrow::Cow;

compiler/rustc_parse/src/lexer/mod.rs

@@ -128,7 +128,7 @@ impl<'a> StringReader<'a> {
     }
 
     /// Turns simple `rustc_lexer::TokenKind` enum into a rich
-    /// `librustc_ast::TokenKind`. This turns strings into interned
+    /// `rustc_ast::TokenKind`. This turns strings into interned
     /// symbols and runs additional validation.
     fn cook_lexer_token(&self, token: rustc_lexer::TokenKind, start: BytePos) -> Option<TokenKind> {
         Some(match token {

compiler/rustc_query_system/src/dep_graph/dep_node.rs

@@ -26,7 +26,7 @@
 //!   could not be instantiated because the current compilation session
 //!   contained no `DefId` for thing that had been removed.
 //!
-//! `DepNode` definition happens in `librustc_middle` with the `define_dep_nodes!()` macro.
+//! `DepNode` definition happens in `rustc_middle` with the `define_dep_nodes!()` macro.
 //! This macro defines the `DepKind` enum and a corresponding `DepConstructor` enum. The
 //! `DepConstructor` enum links a `DepKind` to the parameters that are needed at runtime in order
 //! to construct a valid `DepNode` fingerprint.

compiler/rustc_resolve/src/lib.rs

@@ -6,7 +6,7 @@
 //! Paths in macros, imports, expressions, types, patterns are resolved here.
 //! Label and lifetime names are resolved here as well.
 //!
-//! Type-relative name resolution (methods, fields, associated items) happens in `librustc_typeck`.
+//! Type-relative name resolution (methods, fields, associated items) happens in `rustc_typeck`.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(box_patterns)]

compiler/rustc_target/README.md

@@ -1,4 +1,4 @@
-`librustc_target` contains some very low-level details that are
+`rustc_target` contains some very low-level details that are
 specific to different compilation targets and so forth.
 
 For more information about how rustc works, see the [rustc dev guide].

compiler/rustc_target/src/lib.rs

@@ -28,5 +28,5 @@ pub mod spec;
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
 /// This is a hack to allow using the `HashStable_Generic` derive macro
-/// instead of implementing everything in librustc_middle.
+/// instead of implementing everything in `rustc_middle`.
 pub trait HashStableContext {}

compiler/rustc_trait_selection/src/traits/query/mod.rs

@@ -3,7 +3,7 @@
 //! which makes a canonical query by replacing unbound inference
 //! variables and regions, so that results can be reused more broadly.
 //! The providers for the queries defined here can be found in
-//! `librustc_traits`.
+//! `rustc_traits`.
 
 pub mod dropck_outlives;
 pub mod evaluate_obligation;

library/core/src/iter/adapters/peekable.rs

@@ -233,7 +233,6 @@ impl<I: Iterator> Peekable<I> {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(peekable_peek_mut)]
     /// let mut iter = [1, 2, 3].iter().peekable();
     ///
     /// // Like with `peek()`, we can see into the future without advancing the iterator.
@@ -251,7 +250,7 @@ impl<I: Iterator> Peekable<I> {
     /// assert_eq!(iter.collect::<Vec<_>>(), vec![&5, &3]);
     /// ```
     #[inline]
-    #[unstable(feature = "peekable_peek_mut", issue = "78302")]
+    #[stable(feature = "peekable_peek_mut", since = "1.53.0")]
     pub fn peek_mut(&mut self) -> Option<&mut I::Item> {
         let iter = &mut self.iter;
         self.peeked.get_or_insert_with(|| iter.next()).as_mut()

library/core/src/iter/traits/iterator.rs

@@ -937,20 +937,16 @@ pub trait Iterator {
         Enumerate::new(self)
     }
 
-    /// Creates an iterator which can use [`peek`] to look at the next element of
-    /// the iterator without consuming it.
+    /// Creates an iterator which can use the [`peek`] and [`peek_mut`] methods
+    /// to look at the next element of the iterator without consuming it. See
+    /// their documentation for more information.
     ///
-    /// Adds a [`peek`] method to an iterator. See its documentation for
-    /// more information.
+    /// Note that the underlying iterator is still advanced when [`peek`] or
+    /// [`peek_mut`] are called for the first time: In order to retrieve the
+    /// next element, [`next`] is called on the underlying iterator, hence any
+    /// side effects (i.e. anything other than fetching the next value) of
+    /// the [`next`] method will occur.
     ///
-    /// Note that the underlying iterator is still advanced when [`peek`] is
-    /// called for the first time: In order to retrieve the next element,
-    /// [`next`] is called on the underlying iterator, hence any side effects (i.e.
-    /// anything other than fetching the next value) of the [`next`] method
-    /// will occur.
-    ///
-    /// [`peek`]: Peekable::peek
-    /// [`next`]: Iterator::next
     ///
     /// # Examples
     ///
@@ -977,6 +973,32 @@ pub trait Iterator {
     /// assert_eq!(iter.peek(), None);
     /// assert_eq!(iter.next(), None);
     /// ```
+    ///
+    /// Using [`peek_mut`] to mutate the next item without advancing the
+    /// iterator:
+    ///
+    /// ```
+    /// let xs = [1, 2, 3];
+    ///
+    /// let mut iter = xs.iter().peekable();
+    ///
+    /// // `peek_mut()` lets us see into the future
+    /// assert_eq!(iter.peek_mut(), Some(&mut &1));
+    /// assert_eq!(iter.peek_mut(), Some(&mut &1));
+    /// assert_eq!(iter.next(), Some(&1));
+    ///
+    /// if let Some(mut p) = iter.peek_mut() {
+    ///     assert_eq!(*p, &2);
+    ///     // put a value into the iterator
+    ///     *p = &1000;
+    /// }
+    ///
+    /// // The value reappears as the iterator continues
+    /// assert_eq!(iter.collect::<Vec<_>>(), vec![&1000, &3]);
+    /// ```
+    /// [`peek`]: Peekable::peek
+    /// [`peek_mut`]: Peekable::peek_mut
+    /// [`next`]: Iterator::next
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     fn peekable(self) -> Peekable<Self>

library/core/src/lib.rs

@@ -298,7 +298,8 @@ pub mod primitive;
     unused_imports,
     unsafe_op_in_unsafe_fn
 )]
-#[allow(rustdoc::non_autolinks)]
+#[cfg_attr(bootstrap, allow(rustdoc::non_autolinks))]
+#[cfg_attr(not(bootstrap), allow(rustdoc::bare_urls))]
 // FIXME: This annotation should be moved into rust-lang/stdarch after clashing_extern_declarations is
 // merged. It currently cannot because bootstrap fails as the lint hasn't been defined yet.
 #[allow(clashing_extern_declarations)]

library/core/src/pin.rs

@@ -6,7 +6,7 @@
 //! as moving an object with pointers to itself will invalidate them, which could cause undefined
 //! behavior.
 //!
-//! At a high level, a [`Pin<P>`] ensures that the pointee of any pointer type
+//! At a high level, a <code>[Pin]\<P></code> ensures that the pointee of any pointer type
 //! `P` has a stable location in memory, meaning it cannot be moved elsewhere
 //! and its memory cannot be deallocated until it gets dropped. We say that the
 //! pointee is "pinned". Things get more subtle when discussing types that
@@ -14,13 +14,15 @@
 //! for more details.
 //!
 //! By default, all types in Rust are movable. Rust allows passing all types by-value,
-//! and common smart-pointer types such as [`Box<T>`] and `&mut T` allow replacing and
-//! moving the values they contain: you can move out of a [`Box<T>`], or you can use [`mem::swap`].
-//! [`Pin<P>`] wraps a pointer type `P`, so [`Pin`]`<`[`Box`]`<T>>` functions much like a regular
-//! [`Box<T>`]: when a [`Pin`]`<`[`Box`]`<T>>` gets dropped, so do its contents, and the memory gets
-//! deallocated. Similarly, [`Pin`]`<&mut T>` is a lot like `&mut T`. However, [`Pin<P>`] does
-//! not let clients actually obtain a [`Box<T>`] or `&mut T` to pinned data, which implies that you
-//! cannot use operations such as [`mem::swap`]:
+//! and common smart-pointer types such as <code>[Box]\<T></code> and <code>[&mut] T</code> allow
+//! replacing and moving the values they contain: you can move out of a <code>[Box]\<T></code>,
+//! or you can use [`mem::swap`]. <code>[Pin]\<P></code> wraps a pointer type `P`, so
+//! <code>[Pin]<[Box]\<T>></code> functions much like a regular <code>[Box]\<T></code>:
+//! when a <code>[Pin]<[Box]\<T>></code> gets dropped, so do its contents, and the memory gets
+//! deallocated. Similarly, <code>[Pin]<[&mut] T></code> is a lot like <code>[&mut] T</code>.
+//! However, <code>[Pin]\<P></code> does not let clients actually obtain a <code>[Box]\<T></code>
+//! or <code>[&mut] T</code> to pinned data, which implies that you cannot use operations such
+//! as [`mem::swap`]:
 //!
 //! ```
 //! use std::pin::Pin;
@@ -32,18 +34,18 @@
 //! }
 //! ```
 //!
-//! It is worth reiterating that [`Pin<P>`] does *not* change the fact that a Rust compiler
-//! considers all types movable. [`mem::swap`] remains callable for any `T`. Instead, [`Pin<P>`]
-//! prevents certain *values* (pointed to by pointers wrapped in [`Pin<P>`]) from being
-//! moved by making it impossible to call methods that require `&mut T` on them
-//! (like [`mem::swap`]).
+//! It is worth reiterating that <code>[Pin]\<P></code> does *not* change the fact that a Rust
+//! compiler considers all types movable. [`mem::swap`] remains callable for any `T`. Instead,
+//! <code>[Pin]\<P></code> prevents certain *values* (pointed to by pointers wrapped in
+//! <code>[Pin]\<P></code>) from being moved by making it impossible to call methods that require
+//! <code>[&mut] T</code> on them (like [`mem::swap`]).
 //!
-//! [`Pin<P>`] can be used to wrap any pointer type `P`, and as such it interacts with
-//! [`Deref`] and [`DerefMut`]. A [`Pin<P>`] where `P: Deref` should be considered
-//! as a "`P`-style pointer" to a pinned `P::Target` -- so, a [`Pin`]`<`[`Box`]`<T>>` is
-//! an owned pointer to a pinned `T`, and a [`Pin`]`<`[`Rc`]`<T>>` is a reference-counted
-//! pointer to a pinned `T`.
-//! For correctness, [`Pin<P>`] relies on the implementations of [`Deref`] and
+//! <code>[Pin]\<P></code> can be used to wrap any pointer type `P`, and as such it interacts with
+//! [`Deref`] and [`DerefMut`]. A <code>[Pin]\<P></code> where <code>P: [Deref]</code> should be
+//! considered as a "`P`-style pointer" to a pinned <code>P::[Target]</code> – so, a
+//! <code>[Pin]<[Box]\<T>></code> is an owned pointer to a pinned `T`, and a
+//! <code>[Pin]<[Rc]\<T>></code> is a reference-counted pointer to a pinned `T`.
+//! For correctness, <code>[Pin]\<P></code> relies on the implementations of [`Deref`] and
 //! [`DerefMut`] not to move out of their `self` parameter, and only ever to
 //! return a pointer to pinned data when they are called on a pinned pointer.
 //!
@@ -53,19 +55,19 @@
 //! rely on having a stable address. This includes all the basic types (like
 //! [`bool`], [`i32`], and references) as well as types consisting solely of these
 //! types. Types that do not care about pinning implement the [`Unpin`]
-//! auto-trait, which cancels the effect of [`Pin<P>`]. For `T: Unpin`,
-//! [`Pin`]`<`[`Box`]`<T>>` and [`Box<T>`] function identically, as do [`Pin`]`<&mut T>` and
-//! `&mut T`.
+//! auto-trait, which cancels the effect of <code>[Pin]\<P></code>. For <code>T: [Unpin]</code>,
+//! <code>[Pin]<[Box]\<T>></code> and <code>[Box]\<T></code> function identically, as do
+//! <code>[Pin]<[&mut] T></code> and <code>[&mut] T</code>.
 //!
-//! Note that pinning and [`Unpin`] only affect the pointed-to type `P::Target`, not the pointer
-//! type `P` itself that got wrapped in [`Pin<P>`]. For example, whether or not [`Box<T>`] is
-//! [`Unpin`] has no effect on the behavior of [`Pin`]`<`[`Box`]`<T>>` (here, `T` is the
-//! pointed-to type).
+//! Note that pinning and [`Unpin`] only affect the pointed-to type <code>P::[Target]</code>,
+//! not the pointer type `P` itself that got wrapped in <code>[Pin]\<P></code>. For example,
+//! whether or not <code>[Box]\<T></code> is [`Unpin`] has no effect on the behavior of
+//! <code>[Pin]<[Box]\<T>></code> (here, `T` is the pointed-to type).
 //!
 //! # Example: self-referential struct
 //!
 //! Before we go into more details to explain the guarantees and choices
-//! associated with `Pin<T>`, we discuss some examples for how it might be used.
+//! associated with <code>[Pin]\<P></code>, we discuss some examples for how it might be used.
 //! Feel free to [skip to where the theoretical discussion continues](#drop-guarantee).
 //!
 //! ```rust
@@ -129,7 +131,7 @@
 //!
 //! To make this work, every element has pointers to its predecessor and successor in
 //! the list. Elements can only be added when they are pinned, because moving the elements
-//! around would invalidate the pointers. Moreover, the [`Drop`] implementation of a linked
+//! around would invalidate the pointers. Moreover, the [`Drop`][Drop] implementation of a linked
 //! list element will patch the pointers of its predecessor and successor to remove itself
 //! from the list.
 //!
@@ -149,8 +151,8 @@
 //! when [`drop`] is called*.  Only once [`drop`] returns or panics, the memory may be reused.
 //!
 //! Memory can be "invalidated" by deallocation, but also by
-//! replacing a [`Some(v)`] by [`None`], or calling [`Vec::set_len`] to "kill" some elements
-//! off of a vector. It can be repurposed by using [`ptr::write`] to overwrite it without
+//! replacing a <code>[Some]\(v)</code> by [`None`], or calling [`Vec::set_len`] to "kill" some
+//! elements off of a vector. It can be repurposed by using [`ptr::write`] to overwrite it without
 //! calling the destructor first. None of this is allowed for pinned data without calling [`drop`].
 //!
 //! This is exactly the kind of guarantee that the intrusive linked list from the previous
@@ -158,25 +160,25 @@
 //!
 //! Notice that this guarantee does *not* mean that memory does not leak! It is still
 //! completely okay not ever to call [`drop`] on a pinned element (e.g., you can still
-//! call [`mem::forget`] on a [`Pin`]`<`[`Box`]`<T>>`). In the example of the doubly-linked
+//! call [`mem::forget`] on a <code>[Pin]<[Box]\<T>></code>). In the example of the doubly-linked
 //! list, that element would just stay in the list. However you may not free or reuse the storage
 //! *without calling [`drop`]*.
 //!
 //! # `Drop` implementation
 //!
 //! If your type uses pinning (such as the two examples above), you have to be careful
-//! when implementing [`Drop`]. The [`drop`] function takes `&mut self`, but this
+//! when implementing [`Drop`][Drop]. The [`drop`] function takes <code>[&mut] self</code>, but this
 //! is called *even if your type was previously pinned*! It is as if the
 //! compiler automatically called [`Pin::get_unchecked_mut`].
 //!
 //! This can never cause a problem in safe code because implementing a type that
 //! relies on pinning requires unsafe code, but be aware that deciding to make
 //! use of pinning in your type (for example by implementing some operation on
-//! [`Pin`]`<&Self>` or [`Pin`]`<&mut Self>`) has consequences for your [`Drop`]
-//! implementation as well: if an element of your type could have been pinned,
-//! you must treat [`Drop`] as implicitly taking [`Pin`]`<&mut Self>`.
+//! <code>[Pin]<[&]Self></code> or <code>[Pin]<[&mut] Self></code>) has consequences for your
+//! [`Drop`][Drop]implementation as well: if an element of your type could have been pinned,
+//! you must treat [`Drop`][Drop] as implicitly taking <code>[Pin]<[&mut] Self></code>.
 //!
-//! For example, you could implement `Drop` as follows:
+//! For example, you could implement [`Drop`][Drop] as follows:
 //!
 //! ```rust,no_run
 //! # use std::pin::Pin;
@@ -204,18 +206,18 @@
 //! # Projections and Structural Pinning
 //!
 //! When working with pinned structs, the question arises how one can access the
-//! fields of that struct in a method that takes just [`Pin`]`<&mut Struct>`.
+//! fields of that struct in a method that takes just <code>[Pin]<[&mut] Struct></code>.
 //! The usual approach is to write helper methods (so called *projections*)
-//! that turn [`Pin`]`<&mut Struct>` into a reference to the field, but what
-//! type should that reference have? Is it [`Pin`]`<&mut Field>` or `&mut Field`?
+//! that turn <code>[Pin]<[&mut] Struct></code> into a reference to the field, but what type should
+//! that reference have? Is it <code>[Pin]<[&mut] Field></code> or <code>[&mut] Field</code>?
 //! The same question arises with the fields of an `enum`, and also when considering
-//! container/wrapper types such as [`Vec<T>`], [`Box<T>`], or [`RefCell<T>`].
-//! (This question applies to both mutable and shared references, we just
-//! use the more common case of mutable references here for illustration.)
+//! container/wrapper types such as <code>[Vec]\<T></code>, <code>[Box]\<T></code>,
+//! or <code>[RefCell]\<T></code>. (This question applies to both mutable and shared references,
+//! we just use the more common case of mutable references here for illustration.)
 //!
-//! It turns out that it is actually up to the author of the data structure
-//! to decide whether the pinned projection for a particular field turns
-//! [`Pin`]`<&mut Struct>` into [`Pin`]`<&mut Field>` or `&mut Field`. There are some
+//! It turns out that it is actually up to the author of the data structure to decide whether
+//! the pinned projection for a particular field turns <code>[Pin]<[&mut] Struct></code>
+//! into <code>[Pin]<[&mut] Field></code> or <code>[&mut] Field</code>. There are some
 //! constraints though, and the most important constraint is *consistency*:
 //! every field can be *either* projected to a pinned reference, *or* have
 //! pinning removed as part of the projection. If both are done for the same field,
@@ -230,12 +232,12 @@
 //! ## Pinning *is not* structural for `field`
 //!
 //! It may seem counter-intuitive that the field of a pinned struct might not be pinned,
-//! but that is actually the easiest choice: if a [`Pin`]`<&mut Field>` is never created,
+//! but that is actually the easiest choice: if a <code>[Pin]<[&mut] Field></code> is never created,
 //! nothing can go wrong! So, if you decide that some field does not have structural pinning,
 //! all you have to ensure is that you never create a pinned reference to that field.
 //!
 //! Fields without structural pinning may have a projection method that turns
-//! [`Pin`]`<&mut Struct>` into `&mut Field`:
+//! <code>[Pin]<[&mut] Struct></code> into <code>[&mut] Field</code>:
 //!
 //! ```rust,no_run
 //! # use std::pin::Pin;
@@ -249,16 +251,16 @@
 //! }
 //! ```
 //!
-//! You may also `impl Unpin for Struct` *even if* the type of `field`
+//! You may also <code>impl [Unpin] for Struct</code> *even if* the type of `field`
 //! is not [`Unpin`]. What that type thinks about pinning is not relevant
-//! when no [`Pin`]`<&mut Field>` is ever created.
+//! when no <code>[Pin]<[&mut] Field></code> is ever created.
 //!
 //! ## Pinning *is* structural for `field`
 //!
 //! The other option is to decide that pinning is "structural" for `field`,
 //! meaning that if the struct is pinned then so is the field.
 //!
-//! This allows writing a projection that creates a [`Pin`]`<&mut Field>`, thus
+//! This allows writing a projection that creates a <code>[Pin]<[&mut] Field></code>, thus
 //! witnessing that the field is pinned:
 //!
 //! ```rust,no_run
@@ -278,34 +280,36 @@
 //! 1.  The struct must only be [`Unpin`] if all the structural fields are
 //!     [`Unpin`]. This is the default, but [`Unpin`] is a safe trait, so as the author of
 //!     the struct it is your responsibility *not* to add something like
-//!     `impl<T> Unpin for Struct<T>`. (Notice that adding a projection operation
+//!     <code>impl\<T> [Unpin] for Struct\<T></code>. (Notice that adding a projection operation
 //!     requires unsafe code, so the fact that [`Unpin`] is a safe trait does not break
-//!     the principle that you only have to worry about any of this if you use `unsafe`.)
+//!     the principle that you only have to worry about any of this if you use [`unsafe`].)
 //! 2.  The destructor of the struct must not move structural fields out of its argument. This
-//!     is the exact point that was raised in the [previous section][drop-impl]: `drop` takes
-//!     `&mut self`, but the struct (and hence its fields) might have been pinned before.
-//!     You have to guarantee that you do not move a field inside your [`Drop`] implementation.
-//!     In particular, as explained previously, this means that your struct must *not*
-//!     be `#[repr(packed)]`.
+//!     is the exact point that was raised in the [previous section][drop-impl]: [`drop`] takes
+//!     <code>[&mut] self</code>, but the struct (and hence its fields) might have been pinned
+//!     before. You have to guarantee that you do not move a field inside your [`Drop`][Drop]
+//!     implementation. In particular, as explained previously, this means that your struct
+//!     must *not* be `#[repr(packed)]`.
 //!     See that section for how to write [`drop`] in a way that the compiler can help you
 //!     not accidentally break pinning.
 //! 3.  You must make sure that you uphold the [`Drop` guarantee][drop-guarantee]:
 //!     once your struct is pinned, the memory that contains the
 //!     content is not overwritten or deallocated without calling the content's destructors.
-//!     This can be tricky, as witnessed by [`VecDeque<T>`]: the destructor of [`VecDeque<T>`]
-//!     can fail to call [`drop`] on all elements if one of the destructors panics. This violates
-//!     the [`Drop`] guarantee, because it can lead to elements being deallocated without
-//!     their destructor being called. ([`VecDeque<T>`] has no pinning projections, so this
+//!     This can be tricky, as witnessed by <code>[VecDeque]\<T></code>: the destructor of
+//!     <code>[VecDeque]\<T></code> can fail to call [`drop`] on all elements if one of the
+//!     destructors panics. This violates the [`Drop`][Drop] guarantee, because it can lead to
+//!     elements being deallocated without their destructor being called.
+//!     (<code>[VecDeque]\<T></code> has no pinning projections, so this
 //!     does not cause unsoundness.)
 //! 4.  You must not offer any other operations that could lead to data being moved out of
 //!     the structural fields when your type is pinned. For example, if the struct contains an
-//!     [`Option<T>`] and there is a `take`-like operation with type
-//!     `fn(Pin<&mut Struct<T>>) -> Option<T>`,
-//!     that operation can be used to move a `T` out of a pinned `Struct<T>` -- which means
+//!     <code>[Option]\<T></code> and there is a [`take`][Option::take]-like operation with type
+//!     <code>fn([Pin]<[&mut] Struct\<T>>) -> [Option]\<T></code>,
+//!     that operation can be used to move a `T` out of a pinned `Struct<T>` – which means
 //!     pinning cannot be structural for the field holding this data.
 //!
-//!     For a more complex example of moving data out of a pinned type, imagine if [`RefCell<T>`]
-//!     had a method `fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T>`.
+//!     For a more complex example of moving data out of a pinned type,
+//!     imagine if <code>[RefCell]\<T></code> had a method
+//!     <code>fn get_pin_mut(self: [Pin]<[&mut] Self>) -> [Pin]<[&mut] T></code>.
 //!     Then we could do the following:
 //!     ```compile_fail
 //!     fn exploit_ref_cell<T>(rc: Pin<&mut RefCell<T>>) {
@@ -315,60 +319,65 @@
 //!         let content = &mut *b; // And here we have `&mut T` to the same data.
 //!     }
 //!     ```
-//!     This is catastrophic, it means we can first pin the content of the [`RefCell<T>`]
-//!     (using `RefCell::get_pin_mut`) and then move that content using the mutable
-//!     reference we got later.
+//!     This is catastrophic, it means we can first pin the content of the
+//!     <code>[RefCell]\<T></code> (using <code>[RefCell]::get_pin_mut</code>) and then move that
+//!     content using the mutable reference we got later.
 //!
 //! ## Examples
 //!
-//! For a type like [`Vec<T>`], both possibilities (structural pinning or not) make sense.
-//! A [`Vec<T>`] with structural pinning could have `get_pin`/`get_pin_mut` methods to get
-//! pinned references to elements. However, it could *not* allow calling
-//! [`pop`][Vec::pop] on a pinned [`Vec<T>`] because that would move the (structurally pinned)
-//! contents! Nor could it allow [`push`][Vec::push], which might reallocate and thus also move the
-//! contents.
+//! For a type like <code>[Vec]\<T></code>, both possibilities (structural pinning or not) make
+//! sense. A <code>[Vec]\<T></code> with structural pinning could have `get_pin`/`get_pin_mut`
+//! methods to get pinned references to elements. However, it could *not* allow calling
+//! [`pop`][Vec::pop] on a pinned <code>[Vec]\<T></code> because that would move the (structurally
+//! pinned) contents! Nor could it allow [`push`][Vec::push], which might reallocate and thus also
+//! move the contents.
 //!
-//! A [`Vec<T>`] without structural pinning could `impl<T> Unpin for Vec<T>`, because the contents
-//! are never pinned and the [`Vec<T>`] itself is fine with being moved as well.
+//! A <code>[Vec]\<T></code> without structural pinning could
+//! <code>impl\<T> [Unpin] for [Vec]\<T></code>, because the contents are never pinned
+//! and the <code>[Vec]\<T></code> itself is fine with being moved as well.
 //! At that point pinning just has no effect on the vector at all.
 //!
 //! In the standard library, pointer types generally do not have structural pinning,
-//! and thus they do not offer pinning projections. This is why `Box<T>: Unpin` holds for all `T`.
-//! It makes sense to do this for pointer types, because moving the `Box<T>`
-//! does not actually move the `T`: the [`Box<T>`] can be freely movable (aka `Unpin`) even if
-//! the `T` is not. In fact, even [`Pin`]`<`[`Box`]`<T>>` and [`Pin`]`<&mut T>` are always
-//! [`Unpin`] themselves, for the same reason: their contents (the `T`) are pinned, but the
-//! pointers themselves can be moved without moving the pinned data. For both [`Box<T>`] and
-//! [`Pin`]`<`[`Box`]`<T>>`, whether the content is pinned is entirely independent of whether the
+//! and thus they do not offer pinning projections. This is why <code>[Box]\<T>: [Unpin]</code>
+//! holds for all `T`. It makes sense to do this for pointer types, because moving the
+//! <code>[Box]\<T></code> does not actually move the `T`: the <code>[Box]\<T></code> can be freely
+//! movable (aka [`Unpin`]) even if the `T` is not. In fact, even <code>[Pin]<[Box]\<T>></code> and
+//! <code>[Pin]<[&mut] T></code> are always [`Unpin`] themselves, for the same reason:
+//! their contents (the `T`) are pinned, but the pointers themselves can be moved without moving
+//! the pinned data. For both <code>[Box]\<T></code> and <code>[Pin]<[Box]\<T>></code>,
+//! whether the content is pinned is entirely independent of whether the
 //! pointer is pinned, meaning pinning is *not* structural.
 //!
 //! When implementing a [`Future`] combinator, you will usually need structural pinning
 //! for the nested futures, as you need to get pinned references to them to call [`poll`].
 //! But if your combinator contains any other data that does not need to be pinned,
 //! you can make those fields not structural and hence freely access them with a
-//! mutable reference even when you just have [`Pin`]`<&mut Self>` (such as in your own
+//! mutable reference even when you just have <code>[Pin]<[&mut] Self></code> (such as in your own
 //! [`poll`] implementation).
 //!
-//! [`Deref`]: crate::ops::Deref
-//! [`DerefMut`]: crate::ops::DerefMut
-//! [`mem::swap`]: crate::mem::swap
-//! [`mem::forget`]: crate::mem::forget
-//! [`Box<T>`]: ../../std/boxed/struct.Box.html
-//! [`Vec<T>`]: ../../std/vec/struct.Vec.html
-//! [`Vec::set_len`]: ../../std/vec/struct.Vec.html#method.set_len
-//! [`Box`]: ../../std/boxed/struct.Box.html
-//! [Vec::pop]: ../../std/vec/struct.Vec.html#method.pop
-//! [Vec::push]: ../../std/vec/struct.Vec.html#method.push
-//! [`Rc`]: ../../std/rc/struct.Rc.html
-//! [`RefCell<T>`]: crate::cell::RefCell
-//! [`drop`]: Drop::drop
-//! [`VecDeque<T>`]: ../../std/collections/struct.VecDeque.html
-//! [`Some(v)`]: Some
-//! [`ptr::write`]: crate::ptr::write
-//! [`Future`]: crate::future::Future
+//! [Deref]: crate::ops::Deref "ops::Deref"
+//! [`Deref`]: crate::ops::Deref "ops::Deref"
+//! [Target]: crate::ops::Deref::Target "ops::Deref::Target"
+//! [`DerefMut`]: crate::ops::DerefMut "ops::DerefMut"
+//! [`mem::swap`]: crate::mem::swap "mem::swap"
+//! [`mem::forget`]: crate::mem::forget "mem::forget"
+//! [Vec]: ../../std/vec/struct.Vec.html "Vec"
+//! [`Vec::set_len`]: ../../std/vec/struct.Vec.html#method.set_len "Vec::set_len"
+//! [Box]: ../../std/boxed/struct.Box.html "Box"
+//! [Vec::pop]: ../../std/vec/struct.Vec.html#method.pop "Vec::pop"
+//! [Vec::push]: ../../std/vec/struct.Vec.html#method.push "Vec::push"
+//! [Rc]: ../../std/rc/struct.Rc.html "rc::Rc"
+//! [RefCell]: crate::cell::RefCell "cell::RefCell"
+//! [`drop`]: Drop::drop "Drop::drop"
+//! [VecDeque]: ../../std/collections/struct.VecDeque.html "collections::VecDeque"
+//! [`ptr::write`]: crate::ptr::write "ptr::write"
+//! [`Future`]: crate::future::Future "future::Future"
 //! [drop-impl]: #drop-implementation
 //! [drop-guarantee]: #drop-guarantee
-//! [`poll`]: crate::future::Future::poll
+//! [`poll`]: crate::future::Future::poll "future::Future::poll"
+//! [&]: ../../std/primitive.reference.html "shared reference"
+//! [&mut]: ../../std/primitive.reference.html "mutable reference"
+//! [`unsafe`]: ../../std/keyword.unsafe.html "keyword unsafe"
 
 #![stable(feature = "pin", since = "1.33.0")]
 

library/core/tests/lib.rs

@@ -66,7 +66,6 @@
 #![feature(unwrap_infallible)]
 #![feature(option_result_unwrap_unchecked)]
 #![feature(result_into_ok_or_err)]
-#![feature(peekable_peek_mut)]
 #![feature(ptr_metadata)]
 #![feature(once_cell)]
 #![feature(unsized_tuple_coercion)]

src/doc/rustdoc/src/lints.md

@@ -294,17 +294,14 @@ warning: unclosed HTML tag `h1`
 warning: 2 warnings emitted
 ```
 
-## non_autolinks
+## bare_urls
 
-This lint is **nightly-only** and **warns by default**. It detects links which
-could use the "automatic" link syntax. For example:
+This lint is **warn-by-default**. It detects URLs which are not links.
+For example:
 
 ```rust
 /// http://example.org
-/// [http://example.com](http://example.com)
 /// [http://example.net]
-///
-/// [http://example.com]: http://example.com
 pub fn foo() {}
 ```
 
@@ -312,22 +309,18 @@ Which will give:
 
 ```text
 warning: this URL is not a hyperlink
- --> foo.rs:1:5
+ --> links.rs:1:5
   |
 1 | /// http://example.org
   |     ^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://example.org>`
   |
-  = note: `#[warn(rustdoc::non_autolinks)]` on by default
-
-warning: unneeded long form for URL
- --> foo.rs:2:5
-  |
-2 | /// [http://example.com](http://example.com)
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://example.com>`
+  = note: `#[warn(rustdoc::bare_urls)]` on by default
 
 warning: this URL is not a hyperlink
- --> foo.rs:3:6
+ --> links.rs:3:6
   |
 3 | /// [http://example.net]
   |      ^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://example.net>`
+
+warning: 2 warnings emitted
 ```

src/librustdoc/html/highlight.rs

@@ -136,6 +136,16 @@ impl Iterator for TokenIter<'a> {
     }
 }
 
+fn get_real_ident_class(text: &str, edition: Edition) -> Class {
+    match text {
+        "ref" | "mut" => Class::RefKeyWord,
+        "self" | "Self" => Class::Self_,
+        "false" | "true" => Class::Bool,
+        _ if Symbol::intern(text).is_reserved(|| edition) => Class::KeyWord,
+        _ => Class::Ident,
+    }
+}
+
 /// Processes program tokens, classifying strings of text by highlighting
 /// category (`Class`).
 struct Classifier<'a> {
@@ -144,6 +154,8 @@ struct Classifier<'a> {
     in_macro: bool,
     in_macro_nonterminal: bool,
     edition: Edition,
+    byte_pos: u32,
+    src: &'a str,
 }
 
 impl<'a> Classifier<'a> {
@@ -155,6 +167,68 @@ impl<'a> Classifier<'a> {
             in_macro: false,
             in_macro_nonterminal: false,
             edition,
+            byte_pos: 0,
+            src,
+        }
+    }
+
+    /// Concatenate colons and idents as one when possible.
+    fn get_full_ident_path(&mut self) -> Vec<(TokenKind, usize, usize)> {
+        let start = self.byte_pos as usize;
+        let mut pos = start;
+        let mut has_ident = false;
+        let edition = self.edition;
+
+        loop {
+            let mut nb = 0;
+            while let Some((TokenKind::Colon, _)) = self.tokens.peek() {
+                self.tokens.next();
+                nb += 1;
+            }
+            // Ident path can start with "::" but if we already have content in the ident path,
+            // the "::" is mandatory.
+            if has_ident && nb == 0 {
+                return vec![(TokenKind::Ident, start, pos)];
+            } else if nb != 0 && nb != 2 {
+                if has_ident {
+                    return vec![(TokenKind::Ident, start, pos), (TokenKind::Colon, pos, pos + nb)];
+                } else {
+                    return vec![(TokenKind::Colon, pos, pos + nb)];
+                }
+            }
+
+            if let Some((Class::Ident, text)) = self.tokens.peek().map(|(token, text)| {
+                if *token == TokenKind::Ident {
+                    let class = get_real_ident_class(text, edition);
+                    (class, text)
+                } else {
+                    // Doesn't matter which Class we put in here...
+                    (Class::Comment, text)
+                }
+            }) {
+                // We only "add" the colon if there is an ident behind.
+                pos += text.len() + nb;
+                has_ident = true;
+                self.tokens.next();
+            } else if nb > 0 && has_ident {
+                return vec![(TokenKind::Ident, start, pos), (TokenKind::Colon, pos, pos + nb)];
+            } else if nb > 0 {
+                return vec![(TokenKind::Colon, pos, pos + nb)];
+            } else if has_ident {
+                return vec![(TokenKind::Ident, start, pos)];
+            } else {
+                return Vec::new();
+            }
+        }
+    }
+
+    /// Wraps the tokens iteration to ensure that the byte_pos is always correct.
+    fn next(&mut self) -> Option<(TokenKind, &'a str)> {
+        if let Some((kind, text)) = self.tokens.next() {
+            self.byte_pos += text.len() as u32;
+            Some((kind, text))
+        } else {
+            None
         }
     }
 
@@ -165,8 +239,25 @@ impl<'a> Classifier<'a> {
     /// token is used.
     fn highlight(mut self, sink: &mut dyn FnMut(Highlight<'a>)) {
         with_default_session_globals(|| {
-            while let Some((token, text)) = self.tokens.next() {
+            loop {
+                if self
+                    .tokens
+                    .peek()
+                    .map(|t| matches!(t.0, TokenKind::Colon | TokenKind::Ident))
+                    .unwrap_or(false)
+                {
+                    let tokens = self.get_full_ident_path();
+                    for (token, start, end) in tokens {
+                        let text = &self.src[start..end];
                         self.advance(token, text, sink);
+                        self.byte_pos += text.len() as u32;
+                    }
+                }
+                if let Some((token, text)) = self.next() {
+                    self.advance(token, text, sink);
+                } else {
+                    break;
+                }
             }
         })
     }
@@ -203,12 +294,12 @@ impl<'a> Classifier<'a> {
             },
             TokenKind::And => match lookahead {
                 Some(TokenKind::And) => {
-                    let _and = self.tokens.next();
+                    self.next();
                     sink(Highlight::Token { text: "&&", class: Some(Class::Op) });
                     return;
                 }
                 Some(TokenKind::Eq) => {
-                    let _eq = self.tokens.next();
+                    self.next();
                     sink(Highlight::Token { text: "&=", class: Some(Class::Op) });
                     return;
                 }
@@ -260,7 +351,7 @@ impl<'a> Classifier<'a> {
                 match lookahead {
                     // Case 1: #![inner_attribute]
                     Some(TokenKind::Bang) => {
-                        let _not = self.tokens.next().unwrap();
+                        self.next();
                         if let Some(TokenKind::OpenBracket) = self.peek() {
                             self.in_attribute = true;
                             sink(Highlight::EnterSpan { class: Class::Attribute });
@@ -304,20 +395,18 @@ impl<'a> Classifier<'a> {
                 sink(Highlight::Token { text, class: None });
                 return;
             }
-            TokenKind::Ident => match text {
-                "ref" | "mut" => Class::RefKeyWord,
-                "self" | "Self" => Class::Self_,
-                "false" | "true" => Class::Bool,
+            TokenKind::Ident => match get_real_ident_class(text, self.edition) {
+                Class::Ident => match text {
                     "Option" | "Result" => Class::PreludeTy,
                     "Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
-                // Keywords are also included in the identifier set.
-                _ if Symbol::intern(text).is_reserved(|| self.edition) => Class::KeyWord,
                     _ if self.in_macro_nonterminal => {
                         self.in_macro_nonterminal = false;
                         Class::MacroNonTerminal
                     }
                     _ => Class::Ident,
                 },
+                c => c,
+            },
             TokenKind::RawIdent => Class::Ident,
             TokenKind::Lifetime { .. } => Class::Lifetime,
         };

src/librustdoc/html/highlight/fixtures/sample.html

@@ -10,6 +10,8 @@
 </style>
 <pre><code><span class="attribute">#![<span class="ident">crate_type</span> <span class="op">=</span> <span class="string">&quot;lib&quot;</span>]</span>
 
+<span class="kw">use</span> <span class="ident">std::path</span>::{<span class="ident">Path</span>, <span class="ident">PathBuf</span>};
+
 <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">&quot;linux&quot;</span>)]</span>
 <span class="kw">fn</span> <span class="ident">main</span>() {
     <span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="bool-val">true</span> <span class="op">&amp;&amp;</span> <span class="bool-val">false</span> <span class="op">|</span><span class="op">|</span> <span class="bool-val">true</span>;
@@ -19,6 +21,14 @@
     <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="kw-2">*</span><span class="ident">foo</span>;
     <span class="macro">mac!</span>(<span class="ident">foo</span>, <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">bar</span>);
     <span class="macro">assert!</span>(<span class="self">self</span>.<span class="ident">length</span> <span class="op">&lt;</span> <span class="ident">N</span> <span class="op">&amp;&amp;</span> <span class="ident">index</span> <span class="op">&lt;</span><span class="op">=</span> <span class="self">self</span>.<span class="ident">length</span>);
+    <span class="ident">::std::env::var</span>(<span class="string">&quot;gateau&quot;</span>).<span class="ident">is_ok</span>();
+    <span class="attribute">#[<span class="ident">rustfmt::skip</span>]</span>
+    <span class="kw">let</span> <span class="ident">s</span>:<span class="ident">std</span><span class="ident">::path::PathBuf</span> <span class="op">=</span> <span class="ident">std::path::PathBuf::new</span>();
+    <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">String::new</span>();
+
+    <span class="kw">match</span> <span class="kw-2">&amp;</span><span class="ident">s</span> {
+        <span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">x</span> <span class="op">=</span><span class="op">&gt;</span> {}
+    }
 }
 
 <span class="macro">macro_rules!</span> <span class="ident">bar</span> {

src/librustdoc/html/highlight/fixtures/sample.rs

@@ -1,5 +1,7 @@
 #![crate_type = "lib"]
 
+use std::path::{Path, PathBuf};
+
 #[cfg(target_os = "linux")]
 fn main() {
     let foo = true && false || true;
@@ -9,6 +11,14 @@ fn main() {
     let _ = *foo;
     mac!(foo, &mut bar);
     assert!(self.length < N && index <= self.length);
+    ::std::env::var("gateau").is_ok();
+    #[rustfmt::skip]
+    let s:std::path::PathBuf = std::path::PathBuf::new();
+    let mut s = String::new();
+
+    match &s {
+        ref mut x => {}
+    }
 }
 
 macro_rules! bar {

src/librustdoc/lint.rs

@@ -148,14 +148,13 @@ declare_rustdoc_lint! {
 }
 
 declare_rustdoc_lint! {
-    /// The `non_autolinks` lint detects when a URL could be written using
-    /// only angle brackets. This is a `rustdoc` only lint, see the
-    /// documentation in the [rustdoc book].
+    /// The `bare_urls` lint detects when a URL is not a hyperlink.
+    /// This is a `rustdoc` only lint, see the documentation in the [rustdoc book].
     ///
-    /// [rustdoc book]: ../../../rustdoc/lints.html#non_autolinks
-    NON_AUTOLINKS,
+    /// [rustdoc book]: ../../../rustdoc/lints.html#bare_urls
+    BARE_URLS,
     Warn,
-    "detects URLs that could be written using only angle brackets"
+    "detects URLs that are not hyperlinks"
 }
 
 crate static RUSTDOC_LINTS: Lazy<Vec<&'static Lint>> = Lazy::new(|| {
@@ -166,7 +165,7 @@ crate static RUSTDOC_LINTS: Lazy<Vec<&'static Lint>> = Lazy::new(|| {
         PRIVATE_DOC_TESTS,
         INVALID_CODEBLOCK_ATTRIBUTES,
         INVALID_HTML_TAGS,
-        NON_AUTOLINKS,
+        BARE_URLS,
         MISSING_CRATE_LEVEL_DOCS,
     ]
 });
@@ -185,4 +184,6 @@ crate fn register_lints(_sess: &Session, lint_store: &mut LintStore) {
     }
     lint_store
         .register_renamed("intra_doc_link_resolution_failure", "rustdoc::broken_intra_doc_links");
+    lint_store.register_renamed("non_autolinks", "rustdoc::bare_urls");
+    lint_store.register_renamed("rustdoc::non_autolinks", "rustdoc::bare_urls");
 }

src/librustdoc/passes/bare_urls.rs

@@ -4,37 +4,42 @@ use crate::core::DocContext;
 use crate::fold::DocFolder;
 use crate::html::markdown::opts;
 use core::ops::Range;
-use pulldown_cmark::{Event, LinkType, Parser, Tag};
+use pulldown_cmark::{Event, Parser, Tag};
 use regex::Regex;
 use rustc_errors::Applicability;
+use std::lazy::SyncLazy;
+use std::mem;
 
-crate const CHECK_NON_AUTOLINKS: Pass = Pass {
-    name: "check-non-autolinks",
-    run: check_non_autolinks,
-    description: "detects URLs that could be linkified",
+crate const CHECK_BARE_URLS: Pass = Pass {
+    name: "check-bare-urls",
+    run: check_bare_urls,
+    description: "detects URLs that are not hyperlinks",
 };
 
-const URL_REGEX: &str = concat!(
+const URL_REGEX: SyncLazy<Regex> = SyncLazy::new(|| {
+    Regex::new(concat!(
         r"https?://",                          // url scheme
         r"([-a-zA-Z0-9@:%._\+~#=]{2,256}\.)+", // one or more subdomains
         r"[a-zA-Z]{2,63}",                     // root domain
         r"\b([-a-zA-Z0-9@:%_\+.~#?&/=]*)"      // optional query or url fragments
-);
+    ))
+    .expect("failed to build regex")
+});
 
-struct NonAutolinksLinter<'a, 'tcx> {
+struct BareUrlsLinter<'a, 'tcx> {
     cx: &'a mut DocContext<'tcx>,
-    regex: Regex,
 }
 
-impl<'a, 'tcx> NonAutolinksLinter<'a, 'tcx> {
+impl<'a, 'tcx> BareUrlsLinter<'a, 'tcx> {
     fn find_raw_urls(
         &self,
         text: &str,
         range: Range<usize>,
         f: &impl Fn(&DocContext<'_>, &str, &str, Range<usize>),
     ) {
+        trace!("looking for raw urls in {}", text);
         // For now, we only check "full" URLs (meaning, starting with "http://" or "https://").
-        for match_ in self.regex.find_iter(&text) {
+        for match_ in URL_REGEX.find_iter(&text) {
             let url = match_.as_str();
             let url_range = match_.range();
             f(
@@ -47,18 +52,11 @@ impl<'a, 'tcx> NonAutolinksLinter<'a, 'tcx> {
     }
 }
 
-crate fn check_non_autolinks(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
-    if !cx.tcx.sess.is_nightly_build() {
-        krate
-    } else {
-        let mut coll =
-            NonAutolinksLinter { cx, regex: Regex::new(URL_REGEX).expect("failed to build regex") };
-
-        coll.fold_crate(krate)
-    }
+crate fn check_bare_urls(krate: Crate, cx: &mut DocContext<'_>) -> Crate {
+    BareUrlsLinter { cx }.fold_crate(krate)
 }
 
-impl<'a, 'tcx> DocFolder for NonAutolinksLinter<'a, 'tcx> {
+impl<'a, 'tcx> DocFolder for BareUrlsLinter<'a, 'tcx> {
     fn fold_item(&mut self, item: Item) -> Option<Item> {
         let hir_id = match DocContext::as_local_hir_id(self.cx.tcx, item.def_id) {
             Some(hir_id) => hir_id,
@@ -73,7 +71,7 @@ impl<'a, 'tcx> DocFolder for NonAutolinksLinter<'a, 'tcx> {
                 let sp = super::source_span_for_markdown_range(cx.tcx, &dox, &range, &item.attrs)
                     .or_else(|| span_of_attrs(&item.attrs))
                     .unwrap_or(item.span.inner());
-                cx.tcx.struct_span_lint_hir(crate::lint::NON_AUTOLINKS, hir_id, sp, |lint| {
+                cx.tcx.struct_span_lint_hir(crate::lint::BARE_URLS, hir_id, sp, |lint| {
                     lint.build(msg)
                         .span_suggestion(
                             sp,
@@ -89,37 +87,16 @@ impl<'a, 'tcx> DocFolder for NonAutolinksLinter<'a, 'tcx> {
 
             while let Some((event, range)) = p.next() {
                 match event {
-                    Event::Start(Tag::Link(kind, _, _)) => {
-                        let ignore = matches!(kind, LinkType::Autolink | LinkType::Email);
-                        let mut title = String::new();
-
-                        while let Some((event, range)) = p.next() {
-                            match event {
-                                Event::End(Tag::Link(_, url, _)) => {
-                                    // NOTE: links cannot be nested, so we don't need to
-                                    // check `kind`
-                                    if url.as_ref() == title && !ignore && self.regex.is_match(&url)
-                                    {
-                                        report_diag(
-                                            self.cx,
-                                            "unneeded long form for URL",
-                                            &url,
-                                            range,
-                                        );
-                                    }
-                                    break;
-                                }
-                                Event::Text(s) if !ignore => title.push_str(&s),
-                                _ => {}
-                            }
-                        }
-                    }
                     Event::Text(s) => self.find_raw_urls(&s, range, &report_diag),
-                    Event::Start(Tag::CodeBlock(_)) => {
-                        // We don't want to check the text inside the code blocks.
+                    // We don't want to check the text inside code blocks or links.
+                    Event::Start(tag @ (Tag::CodeBlock(_) | Tag::Link(..))) => {
                         while let Some((event, _)) = p.next() {
                             match event {
-                                Event::End(Tag::CodeBlock(_)) => break,
+                                Event::End(end)
+                                    if mem::discriminant(&end) == mem::discriminant(&tag) =>
+                                {
+                                    break;
+                                }
                                 _ => {}
                             }
                         }

src/librustdoc/passes/mod.rs

@@ -12,8 +12,8 @@ use crate::core::DocContext;
 mod stripper;
 crate use stripper::*;
 
-mod non_autolinks;
-crate use self::non_autolinks::CHECK_NON_AUTOLINKS;
+mod bare_urls;
+crate use self::bare_urls::CHECK_BARE_URLS;
 
 mod strip_hidden;
 crate use self::strip_hidden::STRIP_HIDDEN;
@@ -90,7 +90,7 @@ crate const PASSES: &[Pass] = &[
     COLLECT_TRAIT_IMPLS,
     CALCULATE_DOC_COVERAGE,
     CHECK_INVALID_HTML_TAGS,
-    CHECK_NON_AUTOLINKS,
+    CHECK_BARE_URLS,
 ];
 
 /// The list of passes run by default.
@@ -105,7 +105,7 @@ crate const DEFAULT_PASSES: &[ConditionalPass] = &[
     ConditionalPass::always(CHECK_CODE_BLOCK_SYNTAX),
     ConditionalPass::always(CHECK_INVALID_HTML_TAGS),
     ConditionalPass::always(PROPAGATE_DOC_CFG),
-    ConditionalPass::always(CHECK_NON_AUTOLINKS),
+    ConditionalPass::always(CHECK_BARE_URLS),
 ];
 
 /// The list of default passes run when `--doc-coverage` is passed to rustdoc.

src/test/rustdoc-ui/renamed-lint-still-applies.rs

@@ -4,3 +4,8 @@
 // stable channel.
 //! [x]
 //~^ ERROR unresolved link
+
+#![deny(rustdoc::non_autolinks)]
+//~^ WARNING renamed to `rustdoc::bare_urls`
+//! http://example.com
+//~^ ERROR not a hyperlink

src/test/rustdoc-ui/renamed-lint-still-applies.stderr

@@ -1,3 +1,11 @@
+warning: lint `rustdoc::non_autolinks` has been renamed to `rustdoc::bare_urls`
+  --> $DIR/renamed-lint-still-applies.rs:8:9
+   |
+LL | #![deny(rustdoc::non_autolinks)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `rustdoc::bare_urls`
+   |
+   = note: `#[warn(renamed_and_removed_lints)]` on by default
+
 error: unresolved link to `x`
   --> $DIR/renamed-lint-still-applies.rs:5:6
    |
@@ -12,5 +20,17 @@ LL | #![deny(broken_intra_doc_links)]
    = note: `#[deny(rustdoc::broken_intra_doc_links)]` implied by `#[deny(broken_intra_doc_links)]`
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
-error: aborting due to previous error
+error: this URL is not a hyperlink
+  --> $DIR/renamed-lint-still-applies.rs:10:5
+   |
+LL | //! http://example.com
+   |     ^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://example.com>`
+   |
+note: the lint level is defined here
+  --> $DIR/renamed-lint-still-applies.rs:8:9
+   |
+LL | #![deny(rustdoc::non_autolinks)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 

src/test/rustdoc-ui/unknown-renamed-lints.rs

@@ -8,8 +8,12 @@
 //~^ ERROR unknown lint: `rustdoc::x`
 #![deny(intra_doc_link_resolution_failure)]
 //~^ ERROR renamed to `rustdoc::broken_intra_doc_links`
-
 #![deny(non_autolinks)]
+//~^ ERROR renamed to `rustdoc::bare_urls`
+#![deny(rustdoc::non_autolinks)]
+//~^ ERROR renamed to `rustdoc::bare_urls`
+
+#![deny(private_doc_tests)]
 // FIXME: the old names for rustdoc lints should warn by default once `rustdoc::` makes it to the
 // stable channel.
 

src/test/rustdoc-ui/unknown-renamed-lints.stderr

@@ -28,19 +28,31 @@ note: the lint level is defined here
 LL | #![deny(renamed_and_removed_lints)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error: lint `non_autolinks` has been renamed to `rustdoc::bare_urls`
+  --> $DIR/unknown-renamed-lints.rs:11:9
+   |
+LL | #![deny(non_autolinks)]
+   |         ^^^^^^^^^^^^^ help: use the new name: `rustdoc::bare_urls`
+
+error: lint `rustdoc::non_autolinks` has been renamed to `rustdoc::bare_urls`
+  --> $DIR/unknown-renamed-lints.rs:13:9
+   |
+LL | #![deny(rustdoc::non_autolinks)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `rustdoc::bare_urls`
+
 error: lint `rustdoc` has been removed: use `rustdoc::all` instead
-  --> $DIR/unknown-renamed-lints.rs:16:9
+  --> $DIR/unknown-renamed-lints.rs:20:9
    |
 LL | #![deny(rustdoc)]
    |         ^^^^^^^
 
 error: unknown lint: `rustdoc::intra_doc_link_resolution_failure`
-  --> $DIR/unknown-renamed-lints.rs:20:9
+  --> $DIR/unknown-renamed-lints.rs:24:9
    |
 LL | #![deny(rustdoc::intra_doc_link_resolution_failure)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: Compilation failed, aborting rustdoc
 
-error: aborting due to 6 previous errors
+error: aborting due to 8 previous errors
 

src/test/rustdoc-ui/url-improvements.rs

@@ -1,14 +1,4 @@
-#![deny(rustdoc::non_autolinks)]
-
-/// [http://aa.com](http://aa.com)
-//~^ ERROR unneeded long form for URL
-/// [http://bb.com]
-//~^ ERROR unneeded long form for URL
-///
-/// [http://bb.com]: http://bb.com
-///
-/// [http://c.com][http://c.com]
-pub fn a() {}
+#![deny(rustdoc::bare_urls)]
 
 /// https://somewhere.com
 //~^ ERROR this URL is not a hyperlink
@@ -54,12 +44,14 @@ pub fn c() {}
 ///
 /// ```
 /// This link should not be linted: http://example.com
+///
+/// Nor this one: <http://example.com> or this one: [x](http://example.com)
 /// ```
 ///
 /// [should_not.lint](should_not.lint)
 pub fn everything_is_fine_here() {}
 
-#[allow(rustdoc::non_autolinks)]
+#[allow(rustdoc::bare_urls)]
 pub mod foo {
     /// https://somewhere.com/a?hello=12&bye=11#xyz
     pub fn bar() {}

src/test/rustdoc-ui/url-improvements.stderr

@@ -1,122 +1,110 @@
-error: unneeded long form for URL
+error: this URL is not a hyperlink
   --> $DIR/url-improvements.rs:3:5
    |
-LL | /// [http://aa.com](http://aa.com)
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://aa.com>`
+LL | /// https://somewhere.com
+   |     ^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com>`
    |
 note: the lint level is defined here
   --> $DIR/url-improvements.rs:1:9
    |
-LL | #![deny(rustdoc::non_autolinks)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^
+LL | #![deny(rustdoc::bare_urls)]
+   |         ^^^^^^^^^^^^^^^^^^
 
-error: unneeded long form for URL
+error: this URL is not a hyperlink
   --> $DIR/url-improvements.rs:5:5
    |
-LL | /// [http://bb.com]
-   |     ^^^^^^^^^^^^^^^ help: use an automatic link instead: `<http://bb.com>`
-
-error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:13:5
-   |
-LL | /// https://somewhere.com
-   |     ^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com>`
-
-error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:15:5
-   |
 LL | /// https://somewhere.com/a
    |     ^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com/a>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:17:5
+  --> $DIR/url-improvements.rs:7:5
    |
 LL | /// https://www.somewhere.com
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://www.somewhere.com>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:19:5
+  --> $DIR/url-improvements.rs:9:5
    |
 LL | /// https://www.somewhere.com/a
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://www.somewhere.com/a>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:21:5
+  --> $DIR/url-improvements.rs:11:5
    |
 LL | /// https://subdomain.example.com
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://subdomain.example.com>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:23:5
+  --> $DIR/url-improvements.rs:13:5
    |
 LL | /// https://somewhere.com?
    |     ^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com?>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:25:5
+  --> $DIR/url-improvements.rs:15:5
    |
 LL | /// https://somewhere.com/a?
    |     ^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com/a?>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:27:5
+  --> $DIR/url-improvements.rs:17:5
    |
 LL | /// https://somewhere.com?hello=12
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com?hello=12>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:29:5
+  --> $DIR/url-improvements.rs:19:5
    |
 LL | /// https://somewhere.com/a?hello=12
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com/a?hello=12>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:31:5
+  --> $DIR/url-improvements.rs:21:5
    |
 LL | /// https://example.com?hello=12#xyz
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://example.com?hello=12#xyz>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:33:5
+  --> $DIR/url-improvements.rs:23:5
    |
 LL | /// https://example.com/a?hello=12#xyz
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://example.com/a?hello=12#xyz>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:35:5
+  --> $DIR/url-improvements.rs:25:5
    |
 LL | /// https://example.com#xyz
    |     ^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://example.com#xyz>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:37:5
+  --> $DIR/url-improvements.rs:27:5
    |
 LL | /// https://example.com/a#xyz
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://example.com/a#xyz>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:39:5
+  --> $DIR/url-improvements.rs:29:5
    |
 LL | /// https://somewhere.com?hello=12&bye=11
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com?hello=12&bye=11>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:41:5
+  --> $DIR/url-improvements.rs:31:5
    |
 LL | /// https://somewhere.com/a?hello=12&bye=11
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com/a?hello=12&bye=11>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:43:5
+  --> $DIR/url-improvements.rs:33:5
    |
 LL | /// https://somewhere.com?hello=12&bye=11#xyz
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com?hello=12&bye=11#xyz>`
 
 error: this URL is not a hyperlink
-  --> $DIR/url-improvements.rs:45:10
+  --> $DIR/url-improvements.rs:35:10
    |
 LL | /// hey! https://somewhere.com/a?hello=12&bye=11#xyz
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use an automatic link instead: `<https://somewhere.com/a?hello=12&bye=11#xyz>`
 
-error: aborting due to 19 previous errors
+error: aborting due to 17 previous errors
 

src/tools/clippy/CHANGELOG.md

@@ -6,11 +6,146 @@ document.
 
 ## Unreleased / In Rust Nightly
 
-[3e41797...master](https://github.com/rust-lang/rust-clippy/compare/3e41797...master)
+[6ed6f1e...master](https://github.com/rust-lang/rust-clippy/compare/6ed6f1e...master)
+
+## Rust 1.52
+
+Current beta, release 2021-05-06
+
+[3e41797...6ed6f1e](https://github.com/rust-lang/rust-clippy/compare/3e41797...6ed6f1e)
+
+### New Lints
+
+* [`from_str_radix_10`]
+  [#6717](https://github.com/rust-lang/rust-clippy/pull/6717)
+* [`implicit_clone`]
+  [#6730](https://github.com/rust-lang/rust-clippy/pull/6730)
+* [`semicolon_if_nothing_returned`]
+  [#6681](https://github.com/rust-lang/rust-clippy/pull/6681)
+* [`manual_flatten`]
+  [#6646](https://github.com/rust-lang/rust-clippy/pull/6646)
+* [`inconsistent_struct_constructor`]
+  [#6769](https://github.com/rust-lang/rust-clippy/pull/6769)
+* [`iter_count`]
+  [#6791](https://github.com/rust-lang/rust-clippy/pull/6791)
+* [`default_numeric_fallback`]
+  [#6662](https://github.com/rust-lang/rust-clippy/pull/6662)
+* [`bytes_nth`]
+  [#6695](https://github.com/rust-lang/rust-clippy/pull/6695)
+* [`filter_map_identity`]
+  [#6685](https://github.com/rust-lang/rust-clippy/pull/6685)
+* [`manual_map`]
+  [#6573](https://github.com/rust-lang/rust-clippy/pull/6573)
+
+### Moves and Deprecations
+
+* Moved [`upper_case_acronyms`] to `pedantic`
+  [#6775](https://github.com/rust-lang/rust-clippy/pull/6775)
+* Moved [`manual_map`] to `nursery`
+  [#6796](https://github.com/rust-lang/rust-clippy/pull/6796)
+* Moved [`unnecessary_wraps`] to `pedantic`
+  [#6765](https://github.com/rust-lang/rust-clippy/pull/6765)
+* Moved [`trivial_regex`] to `nursery`
+  [#6696](https://github.com/rust-lang/rust-clippy/pull/6696)
+* Moved [`naive_bytecount`] to `pedantic`
+  [#6825](https://github.com/rust-lang/rust-clippy/pull/6825)
+* Moved [`upper_case_acronyms`] to `style`
+  [#6788](https://github.com/rust-lang/rust-clippy/pull/6788)
+* Moved [`manual_map`] to `style`
+  [#6801](https://github.com/rust-lang/rust-clippy/pull/6801)
+
+### Enhancements
+
+* [`disallowed_method`]: Now supports functions in addition to methods
+  [#6674](https://github.com/rust-lang/rust-clippy/pull/6674)
+* [`upper_case_acronyms`]: Added a new configuration `upper-case-acronyms-aggressive` to
+  trigger the lint if there is more than one uppercase character next to each other
+  [#6788](https://github.com/rust-lang/rust-clippy/pull/6788)
+* [`collapsible_match`]: Now supports block comparison with different value names
+  [#6754](https://github.com/rust-lang/rust-clippy/pull/6754)
+* [`unnecessary_wraps`]: Will now suggest removing unnecessary wrapped return unit type, like `Option<()>`
+  [#6665](https://github.com/rust-lang/rust-clippy/pull/6665)
+* Improved value usage detection in closures
+  [#6698](https://github.com/rust-lang/rust-clippy/pull/6698)
+
+### False Positive Fixes
+
+* [`use_self`]: No longer lints in macros
+  [#6833](https://github.com/rust-lang/rust-clippy/pull/6833)
+* [`use_self`]: Fixed multiple false positives for: generics, associated types and derive implementations
+  [#6179](https://github.com/rust-lang/rust-clippy/pull/6179)
+* [`missing_inline_in_public_items`]: No longer lints for procedural macros
+  [#6814](https://github.com/rust-lang/rust-clippy/pull/6814)
+* [`inherent_to_string`]: No longer lints on functions with function generics
+  [#6771](https://github.com/rust-lang/rust-clippy/pull/6771)
+* [`doc_markdown`]: Add `OpenDNS` to the default configuration as an allowed identifier
+  [#6783](https://github.com/rust-lang/rust-clippy/pull/6783)
+* [`missing_panics_doc`]: No longer lints on [`unreachable!`](https://doc.rust-lang.org/std/macro.unreachable.html)
+  [#6700](https://github.com/rust-lang/rust-clippy/pull/6700)
+* [`collapsible_if`]: No longer lints on if statements with attributes
+  [#6701](https://github.com/rust-lang/rust-clippy/pull/6701)
+* [`match_same_arms`]: Only considers empty blocks as equal if the tokens contained are the same
+  [#6843](https://github.com/rust-lang/rust-clippy/pull/6843)
+* [`redundant_closure`]: Now ignores macros
+  [#6871](https://github.com/rust-lang/rust-clippy/pull/6871)
+* [`manual_map`]: Fixed false positives when control flow statements like `return`, `break` etc. are used
+  [#6801](https://github.com/rust-lang/rust-clippy/pull/6801)
+* [`vec_init_then_push`]: Fixed false positives for loops and if statements
+  [#6697](https://github.com/rust-lang/rust-clippy/pull/6697)
+* [`len_without_is_empty`]: Will now consider multiple impl blocks and `#[allow]` on
+  the `len` method as well as the type definition.
+  [#6853](https://github.com/rust-lang/rust-clippy/pull/6853)
+* [`let_underscore_drop`]: Only lints on types which implement `Drop`
+  [#6682](https://github.com/rust-lang/rust-clippy/pull/6682)
+* [`unit_arg`]: No longer lints on unit arguments when they come from a path expression.
+  [#6601](https://github.com/rust-lang/rust-clippy/pull/6601)
+* [`cargo_common_metadata`]: No longer lints if 
+  [`publish = false`](https://doc.rust-lang.org/cargo/reference/manifest.html#the-publish-field)
+  is defined in the manifest
+  [#6650](https://github.com/rust-lang/rust-clippy/pull/6650)
+
+### Suggestion Fixes/Improvements
+
+* [`collapsible_match`]: Fixed lint message capitalization
+  [#6766](https://github.com/rust-lang/rust-clippy/pull/6766)
+* [`or_fun_call`]: Improved suggestions for `or_insert(vec![])`
+  [#6790](https://github.com/rust-lang/rust-clippy/pull/6790)
+* [`manual_map`]: No longer expands macros in the suggestions
+  [#6801](https://github.com/rust-lang/rust-clippy/pull/6801)
+* Aligned Clippy's lint messages with the rustc dev guide
+  [#6787](https://github.com/rust-lang/rust-clippy/pull/6787)
+
+### ICE Fixes
+
+* [`zero_sized_map_values`]
+  [#6866](https://github.com/rust-lang/rust-clippy/pull/6866)
+
+### Documentation Improvements
+
+* [`useless_format`]: Improved the documentation example
+  [#6854](https://github.com/rust-lang/rust-clippy/pull/6854)
+* Clippy's [`README.md`]: Includes a new subsection on running Clippy as a rustc wrapper 
+  [#6782](https://github.com/rust-lang/rust-clippy/pull/6782)
+
+### Others
+* Running `cargo clippy` after `cargo check` now works as expected 
+  (`cargo clippy` and `cargo check` no longer shares the same build cache)
+  [#6687](https://github.com/rust-lang/rust-clippy/pull/6687)
+* Cargo now re-runs Clippy if arguments after `--` provided to `cargo clippy` are changed.
+  [#6834](https://github.com/rust-lang/rust-clippy/pull/6834)
+* Extracted Clippy's `utils` module into the new `clippy_utils` crate
+  [#6756](https://github.com/rust-lang/rust-clippy/pull/6756)
+* Clippy lintcheck tool improvements
+  [#6800](https://github.com/rust-lang/rust-clippy/pull/6800)
+  [#6735](https://github.com/rust-lang/rust-clippy/pull/6735)
+  [#6764](https://github.com/rust-lang/rust-clippy/pull/6764)
+  [#6708](https://github.com/rust-lang/rust-clippy/pull/6708)
+  [#6780](https://github.com/rust-lang/rust-clippy/pull/6780)
+  [#6686](https://github.com/rust-lang/rust-clippy/pull/6686)
 
 ## Rust 1.51
 
-Current beta, release 2021-03-25
+Current stable, released 2021-03-25
 
 [4911ab1...3e41797](https://github.com/rust-lang/rust-clippy/compare/4911ab1...3e41797)
 
@@ -125,7 +260,7 @@ Current beta, release 2021-03-25
 
 ## Rust 1.50
 
-Current stable, released 2021-02-11
+Released 2021-02-11
 
 [b20d4c1...4bd77a1](https://github.com/rust-lang/rust-clippy/compare/b20d4c1...4bd77a1)
 
@@ -1970,6 +2105,7 @@ Released 2018-09-13
 [configuration file]: ./rust-clippy#configuration
 [pull3665]: https://github.com/rust-lang/rust-clippy/pull/3665
 [adding_lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
+[`README.md`]: https://github.com/rust-lang/rust-clippy/blob/master/README.md
 
 <!-- lint disable no-unused-definitions -->
 <!-- begin autogenerated links to lint list -->
@@ -1993,6 +2129,7 @@ Released 2018-09-13
 [`borrowed_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrowed_box
 [`box_vec`]: https://rust-lang.github.io/rust-clippy/master/index.html#box_vec
 [`boxed_local`]: https://rust-lang.github.io/rust-clippy/master/index.html#boxed_local
+[`branches_sharing_code`]: https://rust-lang.github.io/rust-clippy/master/index.html#branches_sharing_code
 [`builtin_type_shadow`]: https://rust-lang.github.io/rust-clippy/master/index.html#builtin_type_shadow
 [`bytes_nth`]: https://rust-lang.github.io/rust-clippy/master/index.html#bytes_nth
 [`cargo_common_metadata`]: https://rust-lang.github.io/rust-clippy/master/index.html#cargo_common_metadata
@@ -2233,6 +2370,7 @@ Released 2018-09-13
 [`needless_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_collect
 [`needless_continue`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_continue
 [`needless_doctest_main`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_doctest_main
+[`needless_for_each`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_for_each
 [`needless_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
 [`needless_pass_by_value`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_value
 [`needless_question_mark`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_question_mark
@@ -2246,6 +2384,7 @@ Released 2018-09-13
 [`new_without_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#new_without_default
 [`no_effect`]: https://rust-lang.github.io/rust-clippy/master/index.html#no_effect
 [`non_ascii_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#non_ascii_literal
+[`non_octal_unix_permissions`]: https://rust-lang.github.io/rust-clippy/master/index.html#non_octal_unix_permissions
 [`nonminimal_bool`]: https://rust-lang.github.io/rust-clippy/master/index.html#nonminimal_bool
 [`nonsensical_open_options`]: https://rust-lang.github.io/rust-clippy/master/index.html#nonsensical_open_options
 [`not_unsafe_ptr_arg_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#not_unsafe_ptr_arg_deref
@@ -2253,6 +2392,7 @@ 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_filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#option_filter_map
 [`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

src/tools/clippy/README.md

@@ -5,7 +5,7 @@
 
 A collection of lints to catch common mistakes and improve your [Rust](https://github.com/rust-lang/rust) code.
 
-[There are over 400 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
+[There are over 450 lints included in this crate!](https://rust-lang.github.io/rust-clippy/master/index.html)
 
 Lints are divided into categories, each with a default [lint level](https://doc.rust-lang.org/rustc/lints/levels.html).
 You can choose how much Clippy is supposed to ~~annoy~~ help you by changing the lint level by category.

src/tools/clippy/clippy_dev/src/fmt.rs

@@ -68,7 +68,7 @@ pub fn run(check: bool, verbose: bool) {
                 continue;
             }
 
-            success &= rustfmt(context, &path)?;
+            success &= rustfmt(context, path)?;
         }
 
         Ok(success)

src/tools/clippy/clippy_dev/src/lib.rs

@@ -101,7 +101,7 @@ impl Lint {
 #[must_use]
 pub fn gen_lint_group_list<'a>(lints: impl Iterator<Item = &'a Lint>) -> Vec<String> {
     lints
-        .map(|l| format!("        LintId::of(&{}::{}),", l.module, l.name.to_uppercase()))
+        .map(|l| format!("        LintId::of({}::{}),", l.module, l.name.to_uppercase()))
         .sorted()
         .collect::<Vec<String>>()
 }
@@ -154,17 +154,17 @@ pub fn gen_register_lint_list<'a>(
     let header = "    store.register_lints(&[".to_string();
     let footer = "    ]);".to_string();
     let internal_lints = internal_lints
-        .sorted_by_key(|l| format!("        &{}::{},", l.module, l.name.to_uppercase()))
+        .sorted_by_key(|l| format!("        {}::{},", l.module, l.name.to_uppercase()))
         .map(|l| {
             format!(
-                "        #[cfg(feature = \"internal-lints\")]\n        &{}::{},",
+                "        #[cfg(feature = \"internal-lints\")]\n        {}::{},",
                 l.module,
                 l.name.to_uppercase()
             )
         });
     let other_lints = usable_lints
-        .sorted_by_key(|l| format!("        &{}::{},", l.module, l.name.to_uppercase()))
-        .map(|l| format!("        &{}::{},", l.module, l.name.to_uppercase()))
+        .sorted_by_key(|l| format!("        {}::{},", l.module, l.name.to_uppercase()))
+        .map(|l| format!("        {}::{},", l.module, l.name.to_uppercase()))
         .sorted();
     let mut lint_list = vec![header];
     lint_list.extend(internal_lints);
@@ -550,9 +550,9 @@ fn test_gen_lint_group_list() {
         Lint::new("internal", "internal_style", "abc", None, "module_name"),
     ];
     let expected = vec![
-        "        LintId::of(&module_name::ABC),".to_string(),
-        "        LintId::of(&module_name::INTERNAL),".to_string(),
-        "        LintId::of(&module_name::SHOULD_ASSERT_EQ),".to_string(),
+        "        LintId::of(module_name::ABC),".to_string(),
+        "        LintId::of(module_name::INTERNAL),".to_string(),
+        "        LintId::of(module_name::SHOULD_ASSERT_EQ),".to_string(),
     ];
     assert_eq!(expected, gen_lint_group_list(lints.iter()));
 }

src/tools/clippy/clippy_lints/src/absurd_extreme_comparisons.rs

@@ -0,0 +1,173 @@
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+use crate::consts::{constant, Constant};
+
+use clippy_utils::comparisons::{normalize_comparison, Rel};
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::source::snippet;
+use clippy_utils::ty::is_isize_or_usize;
+use clippy_utils::{clip, int_bits, unsext};
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for comparisons where one side of the relation is
+    /// either the minimum or maximum value for its type and warns if it involves a
+    /// case that is always true or always false. Only integer and boolean types are
+    /// checked.
+    ///
+    /// **Why is this bad?** An expression like `min <= x` may misleadingly imply
+    /// that it is possible for `x` to be less than the minimum. Expressions like
+    /// `max < x` are probably mistakes.
+    ///
+    /// **Known problems:** For `usize` the size of the current compile target will
+    /// be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such
+    /// a comparison to detect target pointer width will trigger this lint. One can
+    /// use `mem::sizeof` and compare its value or conditional compilation
+    /// attributes
+    /// like `#[cfg(target_pointer_width = "64")] ..` instead.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// let vec: Vec<isize> = Vec::new();
+    /// if vec.len() <= 0 {}
+    /// if 100 > i32::MAX {}
+    /// ```
+    pub ABSURD_EXTREME_COMPARISONS,
+    correctness,
+    "a comparison with a maximum or minimum value that is always true or false"
+}
+
+declare_lint_pass!(AbsurdExtremeComparisons => [ABSURD_EXTREME_COMPARISONS]);
+
+impl<'tcx> LateLintPass<'tcx> for AbsurdExtremeComparisons {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if let ExprKind::Binary(ref cmp, lhs, rhs) = expr.kind {
+            if let Some((culprit, result)) = detect_absurd_comparison(cx, cmp.node, lhs, rhs) {
+                if !expr.span.from_expansion() {
+                    let msg = "this comparison involving the minimum or maximum element for this \
+                               type contains a case that is always true or always false";
+
+                    let conclusion = match result {
+                        AbsurdComparisonResult::AlwaysFalse => "this comparison is always false".to_owned(),
+                        AbsurdComparisonResult::AlwaysTrue => "this comparison is always true".to_owned(),
+                        AbsurdComparisonResult::InequalityImpossible => format!(
+                            "the case where the two sides are not equal never occurs, consider using `{} == {}` \
+                             instead",
+                            snippet(cx, lhs.span, "lhs"),
+                            snippet(cx, rhs.span, "rhs")
+                        ),
+                    };
+
+                    let help = format!(
+                        "because `{}` is the {} value for this type, {}",
+                        snippet(cx, culprit.expr.span, "x"),
+                        match culprit.which {
+                            ExtremeType::Minimum => "minimum",
+                            ExtremeType::Maximum => "maximum",
+                        },
+                        conclusion
+                    );
+
+                    span_lint_and_help(cx, ABSURD_EXTREME_COMPARISONS, expr.span, msg, None, &help);
+                }
+            }
+        }
+    }
+}
+
+enum ExtremeType {
+    Minimum,
+    Maximum,
+}
+
+struct ExtremeExpr<'a> {
+    which: ExtremeType,
+    expr: &'a Expr<'a>,
+}
+
+enum AbsurdComparisonResult {
+    AlwaysFalse,
+    AlwaysTrue,
+    InequalityImpossible,
+}
+
+fn is_cast_between_fixed_and_target<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
+    if let ExprKind::Cast(cast_exp, _) = expr.kind {
+        let precast_ty = cx.typeck_results().expr_ty(cast_exp);
+        let cast_ty = cx.typeck_results().expr_ty(expr);
+
+        return is_isize_or_usize(precast_ty) != is_isize_or_usize(cast_ty);
+    }
+
+    false
+}
+
+fn detect_absurd_comparison<'tcx>(
+    cx: &LateContext<'tcx>,
+    op: BinOpKind,
+    lhs: &'tcx Expr<'_>,
+    rhs: &'tcx Expr<'_>,
+) -> Option<(ExtremeExpr<'tcx>, AbsurdComparisonResult)> {
+    use AbsurdComparisonResult::{AlwaysFalse, AlwaysTrue, InequalityImpossible};
+    use ExtremeType::{Maximum, Minimum};
+    // absurd comparison only makes sense on primitive types
+    // primitive types don't implement comparison operators with each other
+    if cx.typeck_results().expr_ty(lhs) != cx.typeck_results().expr_ty(rhs) {
+        return None;
+    }
+
+    // comparisons between fix sized types and target sized types are considered unanalyzable
+    if is_cast_between_fixed_and_target(cx, lhs) || is_cast_between_fixed_and_target(cx, rhs) {
+        return None;
+    }
+
+    let (rel, normalized_lhs, normalized_rhs) = normalize_comparison(op, lhs, rhs)?;
+
+    let lx = detect_extreme_expr(cx, normalized_lhs);
+    let rx = detect_extreme_expr(cx, normalized_rhs);
+
+    Some(match rel {
+        Rel::Lt => {
+            match (lx, rx) {
+                (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, AlwaysFalse), // max < x
+                (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, AlwaysFalse), // x < min
+                _ => return None,
+            }
+        },
+        Rel::Le => {
+            match (lx, rx) {
+                (Some(l @ ExtremeExpr { which: Minimum, .. }), _) => (l, AlwaysTrue), // min <= x
+                (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, InequalityImpossible), // max <= x
+                (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, InequalityImpossible), // x <= min
+                (_, Some(r @ ExtremeExpr { which: Maximum, .. })) => (r, AlwaysTrue), // x <= max
+                _ => return None,
+            }
+        },
+        Rel::Ne | Rel::Eq => return None,
+    })
+}
+
+fn detect_extreme_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<ExtremeExpr<'tcx>> {
+    let ty = cx.typeck_results().expr_ty(expr);
+
+    let cv = constant(cx, cx.typeck_results(), expr)?.0;
+
+    let which = match (ty.kind(), cv) {
+        (&ty::Bool, Constant::Bool(false)) | (&ty::Uint(_), Constant::Int(0)) => ExtremeType::Minimum,
+        (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MIN >> (128 - int_bits(cx.tcx, ity)), ity) => {
+            ExtremeType::Minimum
+        },
+
+        (&ty::Bool, Constant::Bool(true)) => ExtremeType::Maximum,
+        (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MAX >> (128 - int_bits(cx.tcx, ity)), ity) => {
+            ExtremeType::Maximum
+        },
+        (&ty::Uint(uty), Constant::Int(i)) if clip(cx.tcx, u128::MAX, uty) == i => ExtremeType::Maximum,
+
+        _ => return None,
+    };
+    Some(ExtremeExpr { which, expr })
+}

src/tools/clippy/clippy_lints/src/assertions_on_constants.rs

@@ -71,7 +71,7 @@ impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
                 return;
             }
             if_chain! {
-                if let ExprKind::Unary(_, ref lit) = e.kind;
+                if let ExprKind::Unary(_, lit) = e.kind;
                 if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), lit);
                 if is_true;
                 then {
@@ -82,7 +82,7 @@ impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
             if assert_span.from_expansion() {
                 return;
             }
-            if let Some(assert_match) = match_assert_with_message(&cx, e) {
+            if let Some(assert_match) = match_assert_with_message(cx, e) {
                 match assert_match {
                     // matched assert but not message
                     AssertKind::WithoutMessage(false) => lint_false_without_message(),
@@ -113,17 +113,17 @@ enum AssertKind {
 /// where `message` is any expression and `c` is a constant bool.
 fn match_assert_with_message<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<AssertKind> {
     if_chain! {
-        if let ExprKind::If(ref cond, ref then, _) = expr.kind;
-        if let ExprKind::Unary(UnOp::Not, ref expr) = cond.kind;
+        if let ExprKind::If(cond, then, _) = expr.kind;
+        if let ExprKind::Unary(UnOp::Not, expr) = cond.kind;
         // bind the first argument of the `assert!` macro
         if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), expr);
         // block
-        if let ExprKind::Block(ref block, _) = then.kind;
+        if let ExprKind::Block(block, _) = then.kind;
         if block.stmts.is_empty();
         if let Some(block_expr) = &block.expr;
         // inner block is optional. unwrap it if it exists, or use the expression as is otherwise.
         if let Some(begin_panic_call) = match block_expr.kind {
-            ExprKind::Block(ref inner_block, _) => &inner_block.expr,
+            ExprKind::Block(inner_block, _) => &inner_block.expr,
             _ => &block.expr,
         };
         // function call

src/tools/clippy/clippy_lints/src/atomic_ordering.rs

@@ -85,7 +85,7 @@ fn match_ordering_def_path(cx: &LateContext<'_>, did: DefId, orderings: &[&str])
 
 fn check_atomic_load_store(cx: &LateContext<'_>, expr: &Expr<'_>) {
     if_chain! {
-        if let ExprKind::MethodCall(ref method_path, _, args, _) = &expr.kind;
+        if let ExprKind::MethodCall(method_path, _, args, _) = &expr.kind;
         let method = method_path.ident.name.as_str();
         if type_is_atomic(cx, &args[0]);
         if method == "load" || method == "store";
@@ -120,7 +120,7 @@ fn check_atomic_load_store(cx: &LateContext<'_>, expr: &Expr<'_>) {
 
 fn check_memory_fence(cx: &LateContext<'_>, expr: &Expr<'_>) {
     if_chain! {
-        if let ExprKind::Call(ref func, ref args) = expr.kind;
+        if let ExprKind::Call(func, args) = expr.kind;
         if let ExprKind::Path(ref func_qpath) = func.kind;
         if let Some(def_id) = cx.qpath_res(func_qpath, func.hir_id).opt_def_id();
         if ["fence", "compiler_fence"]
@@ -152,7 +152,7 @@ fn opt_ordering_defid(cx: &LateContext<'_>, ord_arg: &Expr<'_>) -> Option<DefId>
 
 fn check_atomic_compare_exchange(cx: &LateContext<'_>, expr: &Expr<'_>) {
     if_chain! {
-        if let ExprKind::MethodCall(ref method_path, _, args, _) = &expr.kind;
+        if let ExprKind::MethodCall(method_path, _, args, _) = &expr.kind;
         let method = method_path.ident.name.as_str();
         if type_is_atomic(cx, &args[0]);
         if method == "compare_exchange" || method == "compare_exchange_weak" || method == "fetch_update";

src/tools/clippy/clippy_lints/src/attrs.rs

@@ -250,12 +250,8 @@ 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() {
-                let ident = &*ident.as_str();
-                match ident {
-                    "allow" | "warn" | "deny" | "forbid" => {
-                        check_clippy_lint_names(cx, ident, items);
-                    },
-                    _ => {},
+                if is_lint_level(ident.name) {
+                    check_clippy_lint_names(cx, ident.name, items);
                 }
                 if items.is_empty() || !attr.has_name(sym::deprecated) {
                     return;
@@ -288,9 +284,7 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                         return;
                     }
                     if let Some(lint_list) = &attr.meta_item_list() {
-                        if let Some(ident) = attr.ident() {
-                            match &*ident.as_str() {
-                                "allow" | "warn" | "deny" | "forbid" => {
+                        if attr.ident().map_or(false, |ident| is_lint_level(ident.name)) {
                             // permit `unused_imports`, `deprecated`, `unreachable_pub`,
                             // `clippy::wildcard_imports`, and `clippy::enum_glob_use` for `use` items
                             // and `unused_imports` for `extern crate` items with `macro_use`
@@ -301,8 +295,7 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                                             || is_word(lint, sym::deprecated)
                                             || is_word(lint, sym!(unreachable_pub))
                                             || is_word(lint, sym!(unused))
-                                                    || extract_clippy_lint(lint)
-                                                        .map_or(false, |s| s == "wildcard_imports")
+                                            || extract_clippy_lint(lint).map_or(false, |s| s == "wildcard_imports")
                                             || extract_clippy_lint(lint).map_or(false, |s| s == "enum_glob_use")
                                         {
                                             return;
@@ -340,9 +333,6 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                                     );
                                 }
                             }
-                                },
-                                _ => {},
-                            }
                         }
                     }
                 }
@@ -371,18 +361,18 @@ fn extract_clippy_lint(lint: &NestedMetaItem) -> Option<SymbolStr> {
         if meta_item.path.segments.len() > 1;
         if let tool_name = meta_item.path.segments[0].ident;
         if tool_name.name == sym::clippy;
-        let lint_name = meta_item.path.segments.last().unwrap().ident.name;
         then {
+            let lint_name = meta_item.path.segments.last().unwrap().ident.name;
             return Some(lint_name.as_str());
         }
     }
     None
 }
 
-fn check_clippy_lint_names(cx: &LateContext<'_>, ident: &str, items: &[NestedMetaItem]) {
+fn check_clippy_lint_names(cx: &LateContext<'_>, name: Symbol, items: &[NestedMetaItem]) {
     for lint in items {
         if let Some(lint_name) = extract_clippy_lint(lint) {
-            if lint_name == "restriction" && ident != "allow" {
+            if lint_name == "restriction" && name != sym::allow {
                 span_lint_and_help(
                     cx,
                     BLANKET_CLIPPY_RESTRICTION_LINTS,
@@ -602,7 +592,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
             if let NestedMetaItem::MetaItem(meta) = item {
                 match &meta.kind {
                     MetaItemKind::List(list) => {
-                        mismatched.extend(find_mismatched_target_os(&list));
+                        mismatched.extend(find_mismatched_target_os(list));
                     },
                     MetaItemKind::Word => {
                         if_chain! {
@@ -629,7 +619,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
         then {
             let mess = "operating system used in target family position";
 
-            span_lint_and_then(cx, MISMATCHED_TARGET_OS, attr.span, &mess, |diag| {
+            span_lint_and_then(cx, MISMATCHED_TARGET_OS, attr.span, mess, |diag| {
                 // Avoid showing the unix suggestion multiple times in case
                 // we have more than one mismatch for unix-like systems
                 let mut unix_suggested = false;
@@ -647,3 +637,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
         }
     }
 }
+
+fn is_lint_level(symbol: Symbol) -> bool {
+    matches!(symbol, sym::allow | sym::warn | sym::deny | sym::forbid)
+}

src/tools/clippy/clippy_lints/src/await_holding_invalid.rs

@@ -101,7 +101,7 @@ impl LateLintPass<'_> for AwaitHolding {
             let typeck_results = cx.tcx.typeck_body(body_id);
             check_interior_types(
                 cx,
-                &typeck_results.generator_interior_types.as_ref().skip_binder(),
+                typeck_results.generator_interior_types.as_ref().skip_binder(),
                 body.value.span,
             );
         }

src/tools/clippy/clippy_lints/src/bytecount.rs

@@ -38,19 +38,17 @@ declare_lint_pass!(ByteCount => [NAIVE_BYTECOUNT]);
 impl<'tcx> LateLintPass<'tcx> for ByteCount {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
         if_chain! {
-            if let ExprKind::MethodCall(ref count, _, ref count_args, _) = expr.kind;
+            if let ExprKind::MethodCall(count, _, count_args, _) = expr.kind;
             if count.ident.name == sym!(count);
             if count_args.len() == 1;
-            if let ExprKind::MethodCall(ref filter, _, ref filter_args, _) = count_args[0].kind;
+            if let ExprKind::MethodCall(filter, _, filter_args, _) = count_args[0].kind;
             if filter.ident.name == sym!(filter);
             if filter_args.len() == 2;
             if let ExprKind::Closure(_, _, body_id, _, _) = filter_args[1].kind;
-            then {
             let body = cx.tcx.hir().body(body_id);
-                if_chain! {
             if body.params.len() == 1;
-                    if let Some(argname) = get_pat_name(&body.params[0].pat);
-                    if let ExprKind::Binary(ref op, ref l, ref r) = body.value.kind;
+            if let Some(argname) = get_pat_name(body.params[0].pat);
+            if let ExprKind::Binary(ref op, l, r) = body.value.kind;
             if op.node == BinOpKind::Eq;
             if match_type(cx,
                        cx.typeck_results().expr_ty(&filter_args[0]).peel_refs(),
@@ -66,7 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for ByteCount {
                 if ty::Uint(UintTy::U8) != *cx.typeck_results().expr_ty(needle).peel_refs().kind() {
                     return;
                 }
-                        let haystack = if let ExprKind::MethodCall(ref path, _, ref args, _) =
+                let haystack = if let ExprKind::MethodCall(path, _, args, _) =
                         filter_args[0].kind {
                     let p = path.ident.name;
                     if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
@@ -92,8 +90,6 @@ impl<'tcx> LateLintPass<'tcx> for ByteCount {
             }
         };
     }
-        };
-    }
 }
 
 fn check_arg(name: Symbol, arg: Symbol, needle: &Expr<'_>) -> bool {
@@ -102,10 +98,10 @@ fn check_arg(name: Symbol, arg: Symbol, needle: &Expr<'_>) -> bool {
 
 fn get_path_name(expr: &Expr<'_>) -> Option<Symbol> {
     match expr.kind {
-        ExprKind::Box(ref e) | ExprKind::AddrOf(BorrowKind::Ref, _, ref e) | ExprKind::Unary(UnOp::Deref, ref e) => {
+        ExprKind::Box(e) | ExprKind::AddrOf(BorrowKind::Ref, _, e) | ExprKind::Unary(UnOp::Deref, e) => {
             get_path_name(e)
         },
-        ExprKind::Block(ref b, _) => {
+        ExprKind::Block(b, _) => {
             if b.stmts.is_empty() {
                 b.expr.as_ref().and_then(|p| get_path_name(p))
             } else {

src/tools/clippy/clippy_lints/src/cargo_common_metadata.rs

@@ -20,11 +20,10 @@ declare_clippy_lint! {
     ///
     /// **Example:**
     /// ```toml
-    /// # This `Cargo.toml` is missing an authors field:
+    /// # This `Cargo.toml` is missing a description field:
     /// [package]
     /// name = "clippy"
     /// version = "0.0.212"
-    /// description = "A bunch of helpful lints to avoid common pitfalls in Rust"
     /// repository = "https://github.com/rust-lang/rust-clippy"
     /// readme = "README.md"
     /// license = "MIT OR Apache-2.0"
@@ -32,14 +31,13 @@ declare_clippy_lint! {
     /// categories = ["development-tools", "development-tools::cargo-plugins"]
     /// ```
     ///
-    /// Should include an authors field like:
+    /// Should include a description field like:
     ///
     /// ```toml
     /// # This `Cargo.toml` includes all common metadata
     /// [package]
     /// name = "clippy"
     /// version = "0.0.212"
-    /// authors = ["Someone <someone@rust-lang.org>"]
     /// description = "A bunch of helpful lints to avoid common pitfalls in Rust"
     /// repository = "https://github.com/rust-lang/rust-clippy"
     /// readme = "README.md"
@@ -97,10 +95,6 @@ impl LateLintPass<'_> for CargoCommonMetadata {
             // only run the lint if publish is `None` (`publish = true` or skipped entirely)
             // or if the vector isn't empty (`publish = ["something"]`)
             if package.publish.as_ref().filter(|publish| publish.is_empty()).is_none() || self.ignore_publish {
-                if is_empty_vec(&package.authors) {
-                    missing_warning(cx, &package, "package.authors");
-                }
-
                 if is_empty_str(&package.description) {
                     missing_warning(cx, &package, "package.description");
                 }

src/tools/clippy/clippy_lints/src/casts/cast_ptr_alignment.rs

@@ -10,7 +10,7 @@ use rustc_target::abi::LayoutOf;
 use super::CAST_PTR_ALIGNMENT;
 
 pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-    if let ExprKind::Cast(ref cast_expr, cast_to) = expr.kind {
+    if let ExprKind::Cast(cast_expr, cast_to) = expr.kind {
         if is_hir_ty_cfg_dependant(cx, cast_to) {
             return;
         }

src/tools/clippy/clippy_lints/src/casts/cast_sign_loss.rs

@@ -30,7 +30,7 @@ fn should_lint(cx: &LateContext<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast
             }
 
             // Don't lint for positive constants.
-            let const_val = constant(cx, &cx.typeck_results(), cast_op);
+            let const_val = constant(cx, cx.typeck_results(), cast_op);
             if_chain! {
                 if let Some((Constant::Int(n), _)) = const_val;
                 if let ty::Int(ity) = *cast_from.kind();
@@ -41,14 +41,14 @@ fn should_lint(cx: &LateContext<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast
             }
 
             // Don't lint for the result of methods that always return non-negative values.
-            if let ExprKind::MethodCall(ref path, _, _, _) = cast_op.kind {
+            if let ExprKind::MethodCall(path, _, _, _) = cast_op.kind {
                 let mut method_name = path.ident.name.as_str();
                 let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"];
 
                 if_chain! {
                     if method_name == "unwrap";
                     if let Some(arglist) = method_chain_args(cast_op, &["unwrap"]);
-                    if let ExprKind::MethodCall(ref inner_path, _, _, _) = &arglist[0][0].kind;
+                    if let ExprKind::MethodCall(inner_path, _, _, _) = &arglist[0][0].kind;
                     then {
                         method_name = inner_path.ident.name.as_str();
                     }

src/tools/clippy/clippy_lints/src/casts/mod.rs

@@ -372,7 +372,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
             return;
         }
 
-        if let ExprKind::Cast(ref cast_expr, cast_to) = expr.kind {
+        if let ExprKind::Cast(cast_expr, cast_to) = expr.kind {
             if is_hir_ty_cfg_dependant(cx, cast_to) {
                 return;
             }

src/tools/clippy/clippy_lints/src/checked_conversions.rs

@@ -64,7 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for CheckedConversions {
 
         let result = if_chain! {
             if !in_external_macro(cx.sess(), item.span);
-            if let ExprKind::Binary(op, ref left, ref right) = &item.kind;
+            if let ExprKind::Binary(op, left, right) = &item.kind;
 
             then {
                 match op.node {
@@ -200,7 +200,7 @@ impl ConversionType {
 /// Check for `expr <= (to_type::MAX as from_type)`
 fn check_upper_bound<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<Conversion<'tcx>> {
     if_chain! {
-         if let ExprKind::Binary(ref op, ref left, ref right) = &expr.kind;
+         if let ExprKind::Binary(ref op, left, right) = &expr.kind;
          if let Some((candidate, check)) = normalize_le_ge(op, left, right);
          if let Some((from, to)) = get_types_from_cast(check, INTS, "max_value", "MAX");
 
@@ -219,7 +219,7 @@ fn check_lower_bound<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<Conversion<'tcx>> {
     }
 
     // First of we need a binary containing the expression & the cast
-    if let ExprKind::Binary(ref op, ref left, ref right) = &expr.kind {
+    if let ExprKind::Binary(ref op, left, right) = &expr.kind {
         normalize_le_ge(op, right, left).and_then(|(l, r)| check_function(l, r))
     } else {
         None
@@ -260,7 +260,7 @@ fn get_types_from_cast<'a>(
     // or `to_type::MAX as from_type`
     let call_from_cast: Option<(&Expr<'_>, &str)> = if_chain! {
         // to_type::max_value(), from_type
-        if let ExprKind::Cast(ref limit, ref from_type) = &expr.kind;
+        if let ExprKind::Cast(limit, from_type) = &expr.kind;
         if let TyKind::Path(ref from_type_path) = &from_type.kind;
         if let Some(from_sym) = int_ty_to_sym(from_type_path);
 
@@ -275,7 +275,7 @@ fn get_types_from_cast<'a>(
     let limit_from: Option<(&Expr<'_>, &str)> = call_from_cast.or_else(|| {
         if_chain! {
             // `from_type::from, to_type::max_value()`
-            if let ExprKind::Call(ref from_func, ref args) = &expr.kind;
+            if let ExprKind::Call(from_func, args) = &expr.kind;
             // `to_type::max_value()`
             if args.len() == 1;
             if let limit = &args[0];
@@ -317,13 +317,12 @@ fn get_types_from_cast<'a>(
 /// Gets the type which implements the called function
 fn get_implementing_type<'a>(path: &QPath<'_>, candidates: &'a [&str], function: &str) -> Option<&'a str> {
     if_chain! {
-        if let QPath::TypeRelative(ref ty, ref path) = &path;
+        if let QPath::TypeRelative(ty, path) = &path;
         if path.ident.name.as_str() == function;
-        if let TyKind::Path(QPath::Resolved(None, ref tp)) = &ty.kind;
+        if let TyKind::Path(QPath::Resolved(None, tp)) = &ty.kind;
         if let [int] = &*tp.segments;
-        let name = &int.ident.name.as_str();
-
         then {
+            let name = &int.ident.name.as_str();
             candidates.iter().find(|c| name == *c).cloned()
         } else {
             None
@@ -334,11 +333,10 @@ fn get_implementing_type<'a>(path: &QPath<'_>, candidates: &'a [&str], function:
 /// Gets the type as a string, if it is a supported integer
 fn int_ty_to_sym<'tcx>(path: &QPath<'_>) -> Option<&'tcx str> {
     if_chain! {
-        if let QPath::Resolved(_, ref path) = *path;
+        if let QPath::Resolved(_, path) = *path;
         if let [ty] = &*path.segments;
-        let name = &ty.ident.name.as_str();
-
         then {
+            let name = &ty.ident.name.as_str();
             INTS.iter().find(|c| name == *c).cloned()
         } else {
             None

src/tools/clippy/clippy_lints/src/cognitive_complexity.rs

@@ -152,7 +152,7 @@ impl<'tcx> Visitor<'tcx> for CcHelper {
             ExprKind::If(_, _, _) => {
                 self.cc += 1;
             },
-            ExprKind::Match(_, ref arms, _) => {
+            ExprKind::Match(_, arms, _) => {
                 if arms.len() > 1 {
                     self.cc += 1;
                 }

src/tools/clippy/clippy_lints/src/collapsible_match.rs

@@ -62,8 +62,8 @@ impl<'tcx> LateLintPass<'tcx> for CollapsibleMatch {
 }
 
 fn check_arm<'tcx>(arm: &Arm<'tcx>, wild_outer_arm: &Arm<'tcx>, cx: &LateContext<'tcx>) {
-    if_chain! {
     let expr = strip_singleton_blocks(arm.body);
+    if_chain! {
         if let ExprKind::Match(expr_in, arms_inner, _) = expr.kind;
         // the outer arm pattern and the inner match
         if expr_in.span.ctxt() == arm.pat.span.ctxt();

src/tools/clippy/clippy_lints/src/comparison_chain.rs

@@ -71,10 +71,8 @@ impl<'tcx> LateLintPass<'tcx> for ComparisonChain {
         }
 
         for cond in conds.windows(2) {
-            if let (
-                &ExprKind::Binary(ref kind1, ref lhs1, ref rhs1),
-                &ExprKind::Binary(ref kind2, ref lhs2, ref rhs2),
-            ) = (&cond[0].kind, &cond[1].kind)
+            if let (&ExprKind::Binary(ref kind1, lhs1, rhs1), &ExprKind::Binary(ref kind2, lhs2, rhs2)) =
+                (&cond[0].kind, &cond[1].kind)
             {
                 if !kind_is_cmp(kind1.node) || !kind_is_cmp(kind2.node) {
                     return;

src/tools/clippy/clippy_lints/src/copies.rs

@@ -1,9 +1,19 @@
-use clippy_utils::diagnostics::span_lint_and_note;
-use clippy_utils::{eq_expr_value, in_macro, search_same, SpanlessEq, SpanlessHash};
-use clippy_utils::{get_parent_expr, if_sequence};
-use rustc_hir::{Block, Expr, ExprKind};
+use clippy_utils::diagnostics::{span_lint_and_note, span_lint_and_then};
+use clippy_utils::source::{first_line_of_span, indent_of, reindent_multiline, snippet, snippet_opt};
+use clippy_utils::{
+    both, count_eq, eq_expr_value, get_enclosing_block, get_parent_expr, if_sequence, in_macro, parent_node_is_if_expr,
+    run_lints, search_same, ContainsName, SpanlessEq, SpanlessHash,
+};
+use if_chain::if_chain;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{Applicability, DiagnosticBuilder};
+use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
+use rustc_hir::{Block, Expr, ExprKind, HirId};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::hir::map::Map;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::{source_map::Span, symbol::Symbol, BytePos};
+use std::borrow::Cow;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for consecutive `if`s with the same condition.
@@ -104,14 +114,53 @@ declare_clippy_lint! {
     "`if` with the same `then` and `else` blocks"
 }
 
-declare_lint_pass!(CopyAndPaste => [IFS_SAME_COND, SAME_FUNCTIONS_IN_IF_CONDITION, IF_SAME_THEN_ELSE]);
+declare_clippy_lint! {
+    /// **What it does:** Checks if the `if` and `else` block contain shared code that can be
+    /// moved out of the blocks.
+    ///
+    /// **Why is this bad?** Duplicate code is less maintainable.
+    ///
+    /// **Known problems:** Hopefully none.
+    ///
+    /// **Example:**
+    /// ```ignore
+    /// let foo = if … {
+    ///     println!("Hello World");
+    ///     13
+    /// } else {
+    ///     println!("Hello World");
+    ///     42
+    /// };
+    /// ```
+    ///
+    /// Could be written as:
+    /// ```ignore
+    /// println!("Hello World");
+    /// let foo = if … {
+    ///     13
+    /// } else {
+    ///     42
+    /// };
+    /// ```
+    pub BRANCHES_SHARING_CODE,
+    complexity,
+    "`if` statement with shared code in all blocks"
+}
+
+declare_lint_pass!(CopyAndPaste => [
+    IFS_SAME_COND,
+    SAME_FUNCTIONS_IN_IF_CONDITION,
+    IF_SAME_THEN_ELSE,
+    BRANCHES_SHARING_CODE
+]);
 
 impl<'tcx> LateLintPass<'tcx> for CopyAndPaste {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if !expr.span.from_expansion() {
+            if let ExprKind::If(_, _, _) = expr.kind {
                 // skip ifs directly in else, it will be checked in the parent if
                 if let Some(&Expr {
-                kind: ExprKind::If(_, _, Some(ref else_expr)),
+                    kind: ExprKind::If(_, _, Some(else_expr)),
                     ..
                 }) = get_parent_expr(cx, expr)
                 {
@@ -121,27 +170,398 @@ impl<'tcx> LateLintPass<'tcx> for CopyAndPaste {
                 }
 
                 let (conds, blocks) = if_sequence(expr);
-            lint_same_then_else(cx, &blocks);
+                // Conditions
                 lint_same_cond(cx, &conds);
                 lint_same_fns_in_if_cond(cx, &conds);
+                // Block duplication
+                lint_same_then_else(cx, &blocks, conds.len() == blocks.len(), expr);
+            }
         }
     }
 }
 
-/// Implementation of `IF_SAME_THEN_ELSE`.
-fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>]) {
-    let eq: &dyn Fn(&&Block<'_>, &&Block<'_>) -> bool =
-        &|&lhs, &rhs| -> bool { SpanlessEq::new(cx).eq_block(lhs, rhs) };
+/// Implementation of `BRANCHES_SHARING_CODE` and `IF_SAME_THEN_ELSE` if the blocks are equal.
+fn lint_same_then_else<'tcx>(
+    cx: &LateContext<'tcx>,
+    blocks: &[&Block<'tcx>],
+    has_conditional_else: bool,
+    expr: &'tcx Expr<'_>,
+) {
+    // We only lint ifs with multiple blocks
+    if blocks.len() < 2 || parent_node_is_if_expr(expr, cx) {
+        return;
+    }
 
-    if let Some((i, j)) = search_same_sequenced(blocks, eq) {
+    // Check if each block has shared code
+    let has_expr = blocks[0].expr.is_some();
+    let (start_eq, mut end_eq, expr_eq) = scan_block_for_eq(cx, blocks);
+
+    // BRANCHES_SHARING_CODE prerequisites
+    if has_conditional_else || (start_eq == 0 && end_eq == 0 && (has_expr && !expr_eq)) {
+        return;
+    }
+
+    // Only the start is the same
+    if start_eq != 0 && end_eq == 0 && (!has_expr || !expr_eq) {
+        let block = blocks[0];
+        let start_stmts = block.stmts.split_at(start_eq).0;
+
+        let mut start_walker = UsedValueFinderVisitor::new(cx);
+        for stmt in start_stmts {
+            intravisit::walk_stmt(&mut start_walker, stmt);
+        }
+
+        emit_branches_sharing_code_lint(
+            cx,
+            start_eq,
+            0,
+            false,
+            check_for_warn_of_moved_symbol(cx, &start_walker.def_symbols, expr),
+            blocks,
+            expr,
+        );
+    } else if end_eq != 0 || (has_expr && expr_eq) {
+        let block = blocks[blocks.len() - 1];
+        let (start_stmts, block_stmts) = block.stmts.split_at(start_eq);
+        let (block_stmts, end_stmts) = block_stmts.split_at(block_stmts.len() - end_eq);
+
+        // Scan start
+        let mut start_walker = UsedValueFinderVisitor::new(cx);
+        for stmt in start_stmts {
+            intravisit::walk_stmt(&mut start_walker, stmt);
+        }
+        let mut moved_syms = start_walker.def_symbols;
+
+        // Scan block
+        let mut block_walker = UsedValueFinderVisitor::new(cx);
+        for stmt in block_stmts {
+            intravisit::walk_stmt(&mut block_walker, stmt);
+        }
+        let mut block_defs = block_walker.defs;
+
+        // Scan moved stmts
+        let mut moved_start: Option<usize> = None;
+        let mut end_walker = UsedValueFinderVisitor::new(cx);
+        for (index, stmt) in end_stmts.iter().enumerate() {
+            intravisit::walk_stmt(&mut end_walker, stmt);
+
+            for value in &end_walker.uses {
+                // Well we can't move this and all prev statements. So reset
+                if block_defs.contains(value) {
+                    moved_start = Some(index + 1);
+                    end_walker.defs.drain().for_each(|x| {
+                        block_defs.insert(x);
+                    });
+
+                    end_walker.def_symbols.clear();
+                }
+            }
+
+            end_walker.uses.clear();
+        }
+
+        if let Some(moved_start) = moved_start {
+            end_eq -= moved_start;
+        }
+
+        let end_linable = block.expr.map_or_else(
+            || end_eq != 0,
+            |expr| {
+                intravisit::walk_expr(&mut end_walker, expr);
+                end_walker.uses.iter().any(|x| !block_defs.contains(x))
+            },
+        );
+
+        if end_linable {
+            end_walker.def_symbols.drain().for_each(|x| {
+                moved_syms.insert(x);
+            });
+        }
+
+        emit_branches_sharing_code_lint(
+            cx,
+            start_eq,
+            end_eq,
+            end_linable,
+            check_for_warn_of_moved_symbol(cx, &moved_syms, expr),
+            blocks,
+            expr,
+        );
+    }
+}
+
+fn scan_block_for_eq(cx: &LateContext<'tcx>, blocks: &[&Block<'tcx>]) -> (usize, usize, bool) {
+    let mut start_eq = usize::MAX;
+    let mut end_eq = usize::MAX;
+    let mut expr_eq = true;
+    for win in blocks.windows(2) {
+        let l_stmts = win[0].stmts;
+        let r_stmts = win[1].stmts;
+
+        // `SpanlessEq` now keeps track of the locals and is therefore context sensitive clippy#6752.
+        // The comparison therefore needs to be done in a way that builds the correct context.
+        let mut evaluator = SpanlessEq::new(cx);
+        let mut evaluator = evaluator.inter_expr();
+
+        let current_start_eq = count_eq(&mut l_stmts.iter(), &mut r_stmts.iter(), |l, r| evaluator.eq_stmt(l, r));
+
+        let current_end_eq = {
+            // We skip the middle statements which can't be equal
+            let end_comparison_count = l_stmts.len().min(r_stmts.len()) - current_start_eq;
+            let it1 = l_stmts.iter().skip(l_stmts.len() - end_comparison_count);
+            let it2 = r_stmts.iter().skip(r_stmts.len() - end_comparison_count);
+            it1.zip(it2)
+                .fold(0, |acc, (l, r)| if evaluator.eq_stmt(l, r) { acc + 1 } else { 0 })
+        };
+        let block_expr_eq = both(&win[0].expr, &win[1].expr, |l, r| evaluator.eq_expr(l, r));
+
+        // IF_SAME_THEN_ELSE
+        if_chain! {
+            if block_expr_eq;
+            if l_stmts.len() == r_stmts.len();
+            if l_stmts.len() == current_start_eq;
+            if run_lints(cx, &[IF_SAME_THEN_ELSE], win[0].hir_id);
+            if run_lints(cx, &[IF_SAME_THEN_ELSE], win[1].hir_id);
+            then {
                 span_lint_and_note(
                     cx,
                     IF_SAME_THEN_ELSE,
-            j.span,
+                    win[0].span,
                     "this `if` has identical blocks",
-            Some(i.span),
+                    Some(win[1].span),
                     "same as this",
                 );
+
+                return (0, 0, false);
+            }
+        }
+
+        start_eq = start_eq.min(current_start_eq);
+        end_eq = end_eq.min(current_end_eq);
+        expr_eq &= block_expr_eq;
+    }
+
+    let has_expr = blocks[0].expr.is_some();
+    if has_expr && !expr_eq {
+        end_eq = 0;
+    }
+
+    // Check if the regions are overlapping. Set `end_eq` to prevent the overlap
+    let min_block_size = blocks.iter().map(|x| x.stmts.len()).min().unwrap();
+    if (start_eq + end_eq) > min_block_size {
+        end_eq = min_block_size - start_eq;
+    }
+
+    (start_eq, end_eq, expr_eq)
+}
+
+fn check_for_warn_of_moved_symbol(
+    cx: &LateContext<'tcx>,
+    symbols: &FxHashSet<Symbol>,
+    if_expr: &'tcx Expr<'_>,
+) -> bool {
+    get_enclosing_block(cx, if_expr.hir_id).map_or(false, |block| {
+        let ignore_span = block.span.shrink_to_lo().to(if_expr.span);
+
+        symbols
+            .iter()
+            .filter(|sym| !sym.as_str().starts_with('_'))
+            .any(move |sym| {
+                let mut walker = ContainsName {
+                    name: *sym,
+                    result: false,
+                };
+
+                // Scan block
+                block
+                    .stmts
+                    .iter()
+                    .filter(|stmt| !ignore_span.overlaps(stmt.span))
+                    .for_each(|stmt| intravisit::walk_stmt(&mut walker, stmt));
+
+                if let Some(expr) = block.expr {
+                    intravisit::walk_expr(&mut walker, expr);
+                }
+
+                walker.result
+            })
+    })
+}
+
+fn emit_branches_sharing_code_lint(
+    cx: &LateContext<'tcx>,
+    start_stmts: usize,
+    end_stmts: usize,
+    lint_end: bool,
+    warn_about_moved_symbol: bool,
+    blocks: &[&Block<'tcx>],
+    if_expr: &'tcx Expr<'_>,
+) {
+    if start_stmts == 0 && !lint_end {
+        return;
+    }
+
+    // (help, span, suggestion)
+    let mut suggestions: Vec<(&str, Span, String)> = vec![];
+    let mut add_expr_note = false;
+
+    // Construct suggestions
+    if start_stmts > 0 {
+        let block = blocks[0];
+        let span_start = first_line_of_span(cx, if_expr.span).shrink_to_lo();
+        let span_end = block.stmts[start_stmts - 1].span.source_callsite();
+
+        let cond_span = first_line_of_span(cx, if_expr.span).until(block.span);
+        let cond_snippet = reindent_multiline(snippet(cx, cond_span, "_"), false, None);
+        let cond_indent = indent_of(cx, cond_span);
+        let moved_span = block.stmts[0].span.source_callsite().to(span_end);
+        let moved_snippet = reindent_multiline(snippet(cx, moved_span, "_"), true, None);
+        let suggestion = moved_snippet.to_string() + "\n" + &cond_snippet + "{";
+        let suggestion = reindent_multiline(Cow::Borrowed(&suggestion), true, cond_indent);
+
+        let span = span_start.to(span_end);
+        suggestions.push(("start", span, suggestion.to_string()));
+    }
+
+    if lint_end {
+        let block = blocks[blocks.len() - 1];
+        let span_end = block.span.shrink_to_hi();
+
+        let moved_start = if end_stmts == 0 && block.expr.is_some() {
+            block.expr.unwrap().span
+        } else {
+            block.stmts[block.stmts.len() - end_stmts].span
+        }
+        .source_callsite();
+        let moved_end = block
+            .expr
+            .map_or_else(|| block.stmts[block.stmts.len() - 1].span, |expr| expr.span)
+            .source_callsite();
+
+        let moved_span = moved_start.to(moved_end);
+        let moved_snipped = reindent_multiline(snippet(cx, moved_span, "_"), true, None);
+        let indent = indent_of(cx, if_expr.span.shrink_to_hi());
+        let suggestion = "}\n".to_string() + &moved_snipped;
+        let suggestion = reindent_multiline(Cow::Borrowed(&suggestion), true, indent);
+
+        let mut span = moved_start.to(span_end);
+        // Improve formatting if the inner block has indention (i.e. normal Rust formatting)
+        let test_span = Span::new(span.lo() - BytePos(4), span.lo(), span.ctxt());
+        if snippet_opt(cx, test_span)
+            .map(|snip| snip == "    ")
+            .unwrap_or_default()
+        {
+            span = span.with_lo(test_span.lo());
+        }
+
+        suggestions.push(("end", span, suggestion.to_string()));
+        add_expr_note = !cx.typeck_results().expr_ty(if_expr).is_unit()
+    }
+
+    let add_optional_msgs = |diag: &mut DiagnosticBuilder<'_>| {
+        if add_expr_note {
+            diag.note("The end suggestion probably needs some adjustments to use the expression result correctly");
+        }
+
+        if warn_about_moved_symbol {
+            diag.warn("Some moved values might need to be renamed to avoid wrong references");
+        }
+    };
+
+    // Emit lint
+    if suggestions.len() == 1 {
+        let (place_str, span, sugg) = suggestions.pop().unwrap();
+        let msg = format!("all if blocks contain the same code at the {}", place_str);
+        let help = format!("consider moving the {} statements out like this", place_str);
+        span_lint_and_then(cx, BRANCHES_SHARING_CODE, span, msg.as_str(), |diag| {
+            diag.span_suggestion(span, help.as_str(), sugg, Applicability::Unspecified);
+
+            add_optional_msgs(diag);
+        });
+    } else if suggestions.len() == 2 {
+        let (_, end_span, end_sugg) = suggestions.pop().unwrap();
+        let (_, start_span, start_sugg) = suggestions.pop().unwrap();
+        span_lint_and_then(
+            cx,
+            BRANCHES_SHARING_CODE,
+            start_span,
+            "all if blocks contain the same code at the start and the end. Here at the start",
+            move |diag| {
+                diag.span_note(end_span, "and here at the end");
+
+                diag.span_suggestion(
+                    start_span,
+                    "consider moving the start statements out like this",
+                    start_sugg,
+                    Applicability::Unspecified,
+                );
+
+                diag.span_suggestion(
+                    end_span,
+                    "and consider moving the end statements out like this",
+                    end_sugg,
+                    Applicability::Unspecified,
+                );
+
+                add_optional_msgs(diag);
+            },
+        );
+    }
+}
+
+/// This visitor collects `HirId`s and Symbols of defined symbols and `HirId`s of used values.
+struct UsedValueFinderVisitor<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+
+    /// The `HirId`s of defined values in the scanned statements
+    defs: FxHashSet<HirId>,
+
+    /// The Symbols of the defined symbols in the scanned statements
+    def_symbols: FxHashSet<Symbol>,
+
+    /// The `HirId`s of the used values
+    uses: FxHashSet<HirId>,
+}
+
+impl<'a, 'tcx> UsedValueFinderVisitor<'a, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>) -> Self {
+        UsedValueFinderVisitor {
+            cx,
+            defs: FxHashSet::default(),
+            def_symbols: FxHashSet::default(),
+            uses: FxHashSet::default(),
+        }
+    }
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for UsedValueFinderVisitor<'a, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::All(self.cx.tcx.hir())
+    }
+
+    fn visit_local(&mut self, l: &'tcx rustc_hir::Local<'tcx>) {
+        let local_id = l.pat.hir_id;
+        self.defs.insert(local_id);
+
+        if let Some(sym) = l.pat.simple_ident() {
+            self.def_symbols.insert(sym.name);
+        }
+
+        if let Some(expr) = l.init {
+            intravisit::walk_expr(self, expr);
+        }
+    }
+
+    fn visit_qpath(&mut self, qpath: &'tcx rustc_hir::QPath<'tcx>, id: HirId, _span: rustc_span::Span) {
+        if let rustc_hir::QPath::Resolved(_, path) = *qpath {
+            if path.segments.len() == 1 {
+                if let rustc_hir::def::Res::Local(var) = self.cx.qpath_res(qpath, id) {
+                    self.uses.insert(var);
+                }
+            }
+        }
     }
 }
 
@@ -198,15 +618,3 @@ fn lint_same_fns_in_if_cond(cx: &LateContext<'_>, conds: &[&Expr<'_>]) {
         );
     }
 }
-
-fn search_same_sequenced<T, Eq>(exprs: &[T], eq: Eq) -> Option<(&T, &T)>
-where
-    Eq: Fn(&T, &T) -> bool,
-{
-    for win in exprs.windows(2) {
-        if eq(&win[0], &win[1]) {
-            return Some((&win[0], &win[1]));
-        }
-    }
-    None
-}

src/tools/clippy/clippy_lints/src/create_dir.rs

@@ -33,7 +33,7 @@ declare_lint_pass!(CreateDir => [CREATE_DIR]);
 impl LateLintPass<'_> for CreateDir {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
         if_chain! {
-            if let ExprKind::Call(ref func, ref args) = expr.kind;
+            if let ExprKind::Call(func, args) = expr.kind;
             if let ExprKind::Path(ref path) = func.kind;
             if let Some(def_id) = cx.qpath_res(path, func.hir_id).opt_def_id();
             if match_def_path(cx, def_id, &paths::STD_FS_CREATE_DIR);

src/tools/clippy/clippy_lints/src/default.rs

@@ -77,16 +77,16 @@ impl LateLintPass<'_> for Default {
         if_chain! {
             // Avoid cases already linted by `field_reassign_with_default`
             if !self.reassigned_linted.contains(&expr.span);
-            if let ExprKind::Call(ref path, ..) = expr.kind;
+            if let ExprKind::Call(path, ..) = expr.kind;
             if !any_parent_is_automatically_derived(cx.tcx, expr.hir_id);
             if let ExprKind::Path(ref qpath) = path.kind;
             if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id();
             if match_def_path(cx, def_id, &paths::DEFAULT_TRAIT_METHOD);
             // Detect and ignore <Foo as Default>::default() because these calls do explicitly name the type.
             if let QPath::Resolved(None, _path) = qpath;
-            then {
             let expr_ty = cx.typeck_results().expr_ty(expr);
-                if let ty::Adt(def, ..) = expr_ty.kind() {
+            if let ty::Adt(def, ..) = expr_ty.kind();
+            then {
                 // TODO: Work out a way to put "whatever the imported way of referencing
                 // this type in this file" rather than a fully-qualified type.
                 let replacement = format!("{}::default()", cx.tcx.def_path_str(def.did));
@@ -102,7 +102,6 @@ impl LateLintPass<'_> for Default {
             }
         }
     }
-    }
 
     #[allow(clippy::too_many_lines)]
     fn check_block<'tcx>(&mut self, cx: &LateContext<'tcx>, block: &Block<'tcx>) {
@@ -202,6 +201,7 @@ impl LateLintPass<'_> for Default {
                 let binding_type = if_chain! {
                     if let ty::Adt(adt_def, substs) = binding_type.kind();
                     if !substs.is_empty();
+                    then {
                         let adt_def_ty_name = cx.tcx.item_name(adt_def.did);
                         let generic_args = substs.iter().collect::<Vec<_>>();
                         let tys_str = generic_args
@@ -209,7 +209,6 @@ impl LateLintPass<'_> for Default {
                             .map(ToString::to_string)
                             .collect::<Vec<_>>()
                             .join(", ");
-                    then {
                         format!("{}::<{}>", adt_def_ty_name, &tys_str)
                     } else {
                         binding_type.to_string()
@@ -247,7 +246,7 @@ impl LateLintPass<'_> for Default {
 /// Checks if the given expression is the `default` method belonging to the `Default` trait.
 fn is_expr_default<'tcx>(expr: &'tcx Expr<'tcx>, cx: &LateContext<'tcx>) -> bool {
     if_chain! {
-        if let ExprKind::Call(ref fn_expr, _) = &expr.kind;
+        if let ExprKind::Call(fn_expr, _) = &expr.kind;
         if let ExprKind::Path(qpath) = &fn_expr.kind;
         if let Res::Def(_, def_id) = cx.qpath_res(qpath, fn_expr.hir_id);
         then {
@@ -263,11 +262,11 @@ fn is_expr_default<'tcx>(expr: &'tcx Expr<'tcx>, cx: &LateContext<'tcx>) -> bool
 fn field_reassigned_by_stmt<'tcx>(this: &Stmt<'tcx>, binding_name: Symbol) -> Option<(Ident, &'tcx Expr<'tcx>)> {
     if_chain! {
         // only take assignments
-        if let StmtKind::Semi(ref later_expr) = this.kind;
-        if let ExprKind::Assign(ref assign_lhs, ref assign_rhs, _) = later_expr.kind;
+        if let StmtKind::Semi(later_expr) = this.kind;
+        if let ExprKind::Assign(assign_lhs, assign_rhs, _) = later_expr.kind;
         // only take assignments to fields where the left-hand side field is a field of
         // the same binding as the previous statement
-        if let ExprKind::Field(ref binding, field_ident) = assign_lhs.kind;
+        if let ExprKind::Field(binding, field_ident) = assign_lhs.kind;
         if let ExprKind::Path(QPath::Resolved(_, path)) = binding.kind;
         if let Some(second_binding_name) = path.segments.last();
         if second_binding_name.ident.name == binding_name;

src/tools/clippy/clippy_lints/src/default_numeric_fallback.rs

@@ -131,8 +131,8 @@ impl<'a, 'tcx> Visitor<'tcx> for NumericFallbackVisitor<'a, 'tcx> {
             },
 
             ExprKind::Struct(_, fields, base) => {
-                if_chain! {
                 let ty = self.cx.typeck_results().expr_ty(expr);
+                if_chain! {
                     if let Some(adt_def) = ty.ty_adt_def();
                     if adt_def.is_struct();
                     if let Some(variant) = adt_def.variants.iter().next();

src/tools/clippy/clippy_lints/src/derive.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then};
 use clippy_utils::paths;
-use clippy_utils::ty::is_copy;
+use clippy_utils::ty::{implements_trait, is_copy};
 use clippy_utils::{get_trait_def_id, is_allowed, is_automatically_derived, match_def_path};
 use if_chain::if_chain;
 use rustc_hir::def_id::DefId;
@@ -12,7 +12,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Span;
+use rustc_span::{def_id::LOCAL_CRATE, source_map::Span};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for deriving `Hash` but implementing `PartialEq`
@@ -199,7 +199,7 @@ fn check_hash_peq<'tcx>(
         then {
             // Look for the PartialEq implementations for `ty`
             cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
-                let peq_is_automatically_derived = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
+                let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
 
                 if peq_is_automatically_derived == hash_is_automatically_derived {
                     return;
@@ -253,7 +253,7 @@ fn check_ord_partial_ord<'tcx>(
         then {
             // Look for the PartialOrd implementations for `ty`
             cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
-                let partial_ord_is_automatically_derived = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
+                let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
 
                 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
                     return;
@@ -293,38 +293,44 @@ fn check_ord_partial_ord<'tcx>(
 
 /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
 fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
-    if cx
-        .tcx
-        .lang_items()
-        .clone_trait()
-        .map_or(false, |id| Some(id) == trait_ref.trait_def_id())
-    {
+    let clone_id = match cx.tcx.lang_items().clone_trait() {
+        Some(id) if trait_ref.trait_def_id() == Some(id) => id,
+        _ => return,
+    };
+    let copy_id = match cx.tcx.lang_items().copy_trait() {
+        Some(id) => id,
+        None => return,
+    };
+    let (ty_adt, ty_subs) = match *ty.kind() {
+        // Unions can't derive clone.
+        ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
+        _ => return,
+    };
+    // If the current self type doesn't implement Copy (due to generic constraints), search to see if
+    // there's a Copy impl for any instance of the adt.
     if !is_copy(cx, ty) {
+        if ty_subs.non_erasable_generics().next().is_some() {
+            let has_copy_impl = cx
+                .tcx
+                .all_local_trait_impls(LOCAL_CRATE)
+                .get(&copy_id)
+                .map_or(false, |impls| {
+                    impls
+                        .iter()
+                        .any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did == adt.did))
+                });
+            if !has_copy_impl {
                 return;
             }
-
-        match *ty.kind() {
-            ty::Adt(def, _) if def.is_union() => return,
-
-            // Some types are not Clone by default but could be cloned “by hand” if necessary
-            ty::Adt(def, substs) => {
-                for variant in &def.variants {
-                    for field in &variant.fields {
-                        if let ty::FnDef(..) = field.ty(cx.tcx, substs).kind() {
+        } else {
             return;
         }
     }
-                    for subst in substs {
-                        if let ty::subst::GenericArgKind::Type(subst) = subst.unpack() {
-                            if let ty::Param(_) = subst.kind() {
+    // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
+    // this impl.
+    if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
         return;
     }
-                        }
-                    }
-                }
-            },
-            _ => (),
-        }
 
     span_lint_and_note(
         cx,
@@ -334,7 +340,6 @@ fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &T
         Some(item.span),
         "consider deriving `Clone` or removing `Copy`",
     );
-    }
 }
 
 /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.

src/tools/clippy/clippy_lints/src/doc.rs

@@ -11,7 +11,7 @@ use rustc_errors::emitter::EmitterWriter;
 use rustc_errors::Handler;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc_hir::{Expr, ExprKind, QPath};
+use rustc_hir::{AnonConst, Expr, ExprKind, QPath};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
@@ -710,16 +710,22 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
 
         // check for `begin_panic`
         if_chain! {
-            if let ExprKind::Call(ref func_expr, _) = expr.kind;
-            if let ExprKind::Path(QPath::Resolved(_, ref path)) = func_expr.kind;
+            if let ExprKind::Call(func_expr, _) = expr.kind;
+            if let ExprKind::Path(QPath::Resolved(_, path)) = func_expr.kind;
             if let Some(path_def_id) = path.res.opt_def_id();
             if match_panic_def_id(self.cx, path_def_id);
             if is_expn_of(expr.span, "unreachable").is_none();
+            if !is_expn_of_debug_assertions(expr.span);
             then {
                 self.panic_span = Some(expr.span);
             }
         }
 
+        // check for `assert_eq` or `assert_ne`
+        if is_expn_of(expr.span, "assert_eq").is_some() || is_expn_of(expr.span, "assert_ne").is_some() {
+            self.panic_span = Some(expr.span);
+        }
+
         // check for `unwrap`
         if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
             let reciever_ty = self.typeck_results.expr_ty(&arglists[0][0]).peel_refs();
@@ -734,7 +740,15 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
         intravisit::walk_expr(self, expr);
     }
 
+    // Panics in const blocks will cause compilation to fail.
+    fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
+
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
     }
 }
+
+fn is_expn_of_debug_assertions(span: Span) -> bool {
+    const MACRO_NAMES: &[&str] = &["debug_assert", "debug_assert_eq", "debug_assert_ne"];
+    MACRO_NAMES.iter().any(|name| is_expn_of(span, name).is_some())
+}

src/tools/clippy/clippy_lints/src/double_comparison.rs

@@ -47,7 +47,7 @@ impl<'tcx> DoubleComparisons {
             },
             _ => return,
         };
-        if !(eq_expr_value(cx, &llhs, &rlhs) && eq_expr_value(cx, &lrhs, &rrhs)) {
+        if !(eq_expr_value(cx, llhs, rlhs) && eq_expr_value(cx, lrhs, rrhs)) {
             return;
         }
         macro_rules! lint_double_comparison {
@@ -88,7 +88,7 @@ impl<'tcx> DoubleComparisons {
 
 impl<'tcx> LateLintPass<'tcx> for DoubleComparisons {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let ExprKind::Binary(ref kind, ref lhs, ref rhs) = expr.kind {
+        if let ExprKind::Binary(ref kind, lhs, rhs) = expr.kind {
             Self::check_binop(cx, kind.node, lhs, rhs, expr.span);
         }
     }

src/tools/clippy/clippy_lints/src/double_parens.rs

@@ -50,7 +50,7 @@ impl EarlyLintPass for DoubleParens {
         match expr.kind {
             ExprKind::Paren(ref in_paren) => match in_paren.kind {
                 ExprKind::Paren(_) | ExprKind::Tup(_) => {
-                    span_lint(cx, DOUBLE_PARENS, expr.span, &msg);
+                    span_lint(cx, DOUBLE_PARENS, expr.span, msg);
                 },
                 _ => {},
             },
@@ -58,7 +58,7 @@ impl EarlyLintPass for DoubleParens {
                 if params.len() == 1 {
                     let param = &params[0];
                     if let ExprKind::Paren(_) = param.kind {
-                        span_lint(cx, DOUBLE_PARENS, param.span, &msg);
+                        span_lint(cx, DOUBLE_PARENS, param.span, msg);
                     }
                 }
             },
@@ -66,7 +66,7 @@ impl EarlyLintPass for DoubleParens {
                 if params.len() == 2 {
                     let param = &params[1];
                     if let ExprKind::Paren(_) = param.kind {
-                        span_lint(cx, DOUBLE_PARENS, param.span, &msg);
+                        span_lint(cx, DOUBLE_PARENS, param.span, msg);
                     }
                 }
             },

src/tools/clippy/clippy_lints/src/drop_forget_ref.rs

@@ -113,7 +113,7 @@ declare_lint_pass!(DropForgetRef => [DROP_REF, FORGET_REF, DROP_COPY, FORGET_COP
 impl<'tcx> LateLintPass<'tcx> for DropForgetRef {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
-            if let ExprKind::Call(ref path, ref args) = expr.kind;
+            if let ExprKind::Call(path, args) = expr.kind;
             if let ExprKind::Path(ref qpath) = path.kind;
             if args.len() == 1;
             if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id();

src/tools/clippy/clippy_lints/src/duration_subsec.rs

@@ -43,8 +43,8 @@ declare_lint_pass!(DurationSubsec => [DURATION_SUBSEC]);
 impl<'tcx> LateLintPass<'tcx> for DurationSubsec {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
-            if let ExprKind::Binary(Spanned { node: BinOpKind::Div, .. }, ref left, ref right) = expr.kind;
-            if let ExprKind::MethodCall(ref method_path, _ , ref args, _) = left.kind;
+            if let ExprKind::Binary(Spanned { node: BinOpKind::Div, .. }, left, right) = expr.kind;
+            if let ExprKind::MethodCall(method_path, _ , args, _) = left.kind;
             if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::DURATION);
             if let Some((Constant::Int(divisor), _)) = constant(cx, cx.typeck_results(), right);
             then {

src/tools/clippy/clippy_lints/src/entry.rs

@@ -57,14 +57,14 @@ declare_lint_pass!(HashMapPass => [MAP_ENTRY]);
 
 impl<'tcx> LateLintPass<'tcx> for HashMapPass {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let ExprKind::If(ref check, ref then_block, ref else_block) = expr.kind {
-            if let ExprKind::Unary(UnOp::Not, ref check) = check.kind {
+        if let ExprKind::If(check, then_block, ref else_block) = expr.kind {
+            if let ExprKind::Unary(UnOp::Not, check) = check.kind {
                 if let Some((ty, map, key)) = check_cond(cx, check) {
                     // in case of `if !m.contains_key(&k) { m.insert(k, v); }`
                     // we can give a better error message
                     let sole_expr = {
                         else_block.is_none()
-                            && if let ExprKind::Block(ref then_block, _) = then_block.kind {
+                            && if let ExprKind::Block(then_block, _) = then_block.kind {
                                 (then_block.expr.is_some() as usize) + then_block.stmts.len() == 1
                             } else {
                                 true
@@ -81,9 +81,9 @@ impl<'tcx> LateLintPass<'tcx> for HashMapPass {
                         sole_expr,
                     };
 
-                    walk_expr(&mut visitor, &**then_block);
+                    walk_expr(&mut visitor, then_block);
                 }
-            } else if let Some(ref else_block) = *else_block {
+            } else if let Some(else_block) = *else_block {
                 if let Some((ty, map, key)) = check_cond(cx, check) {
                     let mut visitor = InsertVisitor {
                         cx,
@@ -103,10 +103,10 @@ impl<'tcx> LateLintPass<'tcx> for HashMapPass {
 
 fn check_cond<'a>(cx: &LateContext<'_>, check: &'a Expr<'a>) -> Option<(&'static str, &'a Expr<'a>, &'a Expr<'a>)> {
     if_chain! {
-        if let ExprKind::MethodCall(ref path, _, ref params, _) = check.kind;
+        if let ExprKind::MethodCall(path, _, params, _) = check.kind;
         if params.len() >= 2;
         if path.ident.name == sym!(contains_key);
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref key) = params[1].kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, key) = params[1].kind;
         then {
             let map = &params[0];
             let obj_ty = cx.typeck_results().expr_ty(map).peel_refs();
@@ -140,7 +140,7 @@ impl<'a, 'tcx, 'b> Visitor<'tcx> for InsertVisitor<'a, 'tcx, 'b> {
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
         if_chain! {
-            if let ExprKind::MethodCall(ref path, _, ref params, _) = expr.kind;
+            if let ExprKind::MethodCall(path, _, params, _) = expr.kind;
             if params.len() == 3;
             if path.ident.name == sym!(insert);
             if get_item_name(self.cx, self.map) == get_item_name(self.cx, &params[0]);

src/tools/clippy/clippy_lints/src/eq_op.rs

@@ -65,12 +65,12 @@ const ASSERT_MACRO_NAMES: [&str; 4] = ["assert_eq", "assert_ne", "debug_assert_e
 impl<'tcx> LateLintPass<'tcx> for EqOp {
     #[allow(clippy::similar_names, clippy::too_many_lines)]
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
-        if let ExprKind::Block(ref block, _) = e.kind {
+        if let ExprKind::Block(block, _) = e.kind {
             for stmt in block.stmts {
                 for amn in &ASSERT_MACRO_NAMES {
                     if_chain! {
                         if is_expn_of(stmt.span, amn).is_some();
-                        if let StmtKind::Semi(ref matchexpr) = stmt.kind;
+                        if let StmtKind::Semi(matchexpr) = stmt.kind;
                         if let Some(macro_args) = higher::extract_assert_macro_args(matchexpr);
                         if macro_args.len() == 2;
                         let (lhs, rhs) = (macro_args[0], macro_args[1]);
@@ -88,12 +88,12 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                 }
             }
         }
-        if let ExprKind::Binary(op, ref left, ref right) = e.kind {
+        if let ExprKind::Binary(op, left, right) = e.kind {
             if e.span.from_expansion() {
                 return;
             }
             let macro_with_not_op = |expr_kind: &ExprKind<'_>| {
-                if let ExprKind::Unary(_, ref expr) = *expr_kind {
+                if let ExprKind::Unary(_, expr) = *expr_kind {
                     in_macro(expr.span)
                 } else {
                     false
@@ -135,7 +135,7 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                     // do not suggest to dereference literals
                     (&ExprKind::Lit(..), _) | (_, &ExprKind::Lit(..)) => {},
                     // &foo == &bar
-                    (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
+                    (&ExprKind::AddrOf(BorrowKind::Ref, _, l), &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
                         let lty = cx.typeck_results().expr_ty(l);
                         let rty = cx.typeck_results().expr_ty(r);
                         let lcpy = is_copy(cx, lty);
@@ -198,7 +198,7 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                         }
                     },
                     // &foo == bar
-                    (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), _) => {
+                    (&ExprKind::AddrOf(BorrowKind::Ref, _, l), _) => {
                         let lty = cx.typeck_results().expr_ty(l);
                         let lcpy = is_copy(cx, lty);
                         if (requires_ref || lcpy)
@@ -222,7 +222,7 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
                         }
                     },
                     // foo == &bar
-                    (_, &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
+                    (_, &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
                         let rty = cx.typeck_results().expr_ty(r);
                         let rcpy = is_copy(cx, rty);
                         if (requires_ref || rcpy)

src/tools/clippy/clippy_lints/src/erasing_op.rs

@@ -34,7 +34,7 @@ impl<'tcx> LateLintPass<'tcx> for ErasingOp {
         if e.span.from_expansion() {
             return;
         }
-        if let ExprKind::Binary(ref cmp, ref left, ref right) = e.kind {
+        if let ExprKind::Binary(ref cmp, left, right) = e.kind {
             match cmp.node {
                 BinOpKind::Mul | BinOpKind::BitAnd => {
                     check(cx, left, e.span);

src/tools/clippy/clippy_lints/src/eta_reduction.rs

@@ -87,7 +87,7 @@ impl<'tcx> LateLintPass<'tcx> for EtaReduction {
 }
 
 fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
-    if let ExprKind::Closure(_, ref decl, eid, _, _) = expr.kind {
+    if let ExprKind::Closure(_, decl, eid, _, _) = expr.kind {
         let body = cx.tcx.hir().body(eid);
         let ex = &body.value;
 
@@ -109,7 +109,7 @@ fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
         }
 
         if_chain!(
-            if let ExprKind::Call(ref caller, ref args) = ex.kind;
+            if let ExprKind::Call(caller, args) = ex.kind;
 
             if let ExprKind::Path(_) = caller.kind;
 
@@ -142,7 +142,7 @@ fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
         );
 
         if_chain!(
-            if let ExprKind::MethodCall(ref path, _, ref args, _) = ex.kind;
+            if let ExprKind::MethodCall(path, _, args, _) = ex.kind;
 
             // Not the same number of arguments, there is no way the closure is the same as the function return;
             if args.len() == decl.inputs.len();
@@ -178,7 +178,7 @@ fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_a
     let actual_type_of_self = &cx.typeck_results().node_type(self_arg.hir_id);
 
     if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
-        if match_borrow_depth(expected_type_of_self, &actual_type_of_self)
+        if match_borrow_depth(expected_type_of_self, actual_type_of_self)
             && implements_trait(cx, actual_type_of_self, trait_id, &[])
         {
             return Some(cx.tcx.def_path_str(trait_id));
@@ -187,8 +187,8 @@ fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_a
 
     cx.tcx.impl_of_method(method_def_id).and_then(|_| {
         //a type may implicitly implement other type's methods (e.g. Deref)
-        if match_types(expected_type_of_self, &actual_type_of_self) {
-            return Some(get_type_name(cx, &actual_type_of_self));
+        if match_types(expected_type_of_self, actual_type_of_self) {
+            return Some(get_type_name(cx, actual_type_of_self));
         }
         None
     })
@@ -196,7 +196,7 @@ 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),
+        (ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(t1, t2),
         (l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
     }
 }
@@ -218,7 +218,7 @@ fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
 fn get_type_name(cx: &LateContext<'_>, ty: Ty<'_>) -> String {
     match ty.kind() {
         ty::Adt(t, _) => cx.tcx.def_path_str(t.did),
-        ty::Ref(_, r, _) => get_type_name(cx, &r),
+        ty::Ref(_, r, _) => get_type_name(cx, r),
         _ => ty.to_string(),
     }
 }
@@ -230,7 +230,7 @@ fn compare_inputs(
     for (closure_input, function_arg) in closure_inputs.zip(call_args) {
         if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
             // XXXManishearth Should I be checking the binding mode here?
-            if let ExprKind::Path(QPath::Resolved(None, ref p)) = function_arg.kind {
+            if let ExprKind::Path(QPath::Resolved(None, p)) = function_arg.kind {
                 if p.segments.len() != 1 {
                     // If it's a proper path, it can't be a local variable
                     return false;

src/tools/clippy/clippy_lints/src/eval_order_dependence.rs

@@ -71,7 +71,7 @@ impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         // Find a write to a local variable.
         match expr.kind {
-            ExprKind::Assign(ref lhs, ..) | ExprKind::AssignOp(_, ref lhs, _) => {
+            ExprKind::Assign(lhs, ..) | ExprKind::AssignOp(_, lhs, _) => {
                 if let Some(var) = path_to_local(lhs) {
                     let mut visitor = ReadVisitor {
                         cx,
@@ -87,12 +87,12 @@ impl<'tcx> LateLintPass<'tcx> for EvalOrderDependence {
     }
     fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
         match stmt.kind {
-            StmtKind::Local(ref local) => {
-                if let Local { init: Some(ref e), .. } = **local {
+            StmtKind::Local(local) => {
+                if let Local { init: Some(e), .. } = local {
                     DivergenceVisitor { cx }.visit_expr(e);
                 }
             },
-            StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
+            StmtKind::Expr(e) | StmtKind::Semi(e) => DivergenceVisitor { cx }.maybe_walk_expr(e),
             StmtKind::Item(..) => {},
         }
     }
@@ -106,7 +106,7 @@ impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
     fn maybe_walk_expr(&mut self, e: &'tcx Expr<'_>) {
         match e.kind {
             ExprKind::Closure(..) => {},
-            ExprKind::Match(ref e, arms, _) => {
+            ExprKind::Match(e, arms, _) => {
                 self.visit_expr(e);
                 for arm in arms {
                     if let Some(Guard::If(if_expr)) = arm.guard {
@@ -130,7 +130,7 @@ impl<'a, 'tcx> Visitor<'tcx> for DivergenceVisitor<'a, 'tcx> {
     fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
         match e.kind {
             ExprKind::Continue(_) | ExprKind::Break(_, _) | ExprKind::Ret(_) => self.report_diverging_sub_expr(e),
-            ExprKind::Call(ref func, _) => {
+            ExprKind::Call(func, _) => {
                 let typ = self.cx.typeck_results().expr_ty(func);
                 match typ.kind() {
                     ty::FnDef(..) | ty::FnPtr(_) => {
@@ -266,10 +266,10 @@ fn check_expr<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, expr: &'tcx Expr<'_>) -
 
 fn check_stmt<'a, 'tcx>(vis: &mut ReadVisitor<'a, 'tcx>, stmt: &'tcx Stmt<'_>) -> StopEarly {
     match stmt.kind {
-        StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => check_expr(vis, expr),
+        StmtKind::Expr(expr) | StmtKind::Semi(expr) => check_expr(vis, expr),
         // If the declaration is of a local variable, check its initializer
         // expression if it has one. Otherwise, keep going.
-        StmtKind::Local(ref local) => local
+        StmtKind::Local(local) => local
             .init
             .as_ref()
             .map_or(StopEarly::KeepGoing, |expr| check_expr(vis, expr)),
@@ -343,7 +343,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReadVisitor<'a, 'tcx> {
 /// Returns `true` if `expr` is the LHS of an assignment, like `expr = ...`.
 fn is_in_assignment_position(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     if let Some(parent) = get_parent_expr(cx, expr) {
-        if let ExprKind::Assign(ref lhs, ..) = parent.kind {
+        if let ExprKind::Assign(lhs, ..) = parent.kind {
             return lhs.hir_id == expr.hir_id;
         }
     }

src/tools/clippy/clippy_lints/src/excessive_bools.rs

@@ -1,9 +1,9 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::{attr_by_name, in_macro, match_path_ast};
+use clippy_utils::{in_macro, match_path_ast};
 use rustc_ast::ast::{AssocItemKind, Extern, FnKind, FnSig, ImplKind, Item, ItemKind, TraitKind, Ty, TyKind};
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::Span;
+use rustc_span::{sym, Span};
 
 use std::convert::TryInto;
 
@@ -138,7 +138,7 @@ impl EarlyLintPass for ExcessiveBools {
         }
         match &item.kind {
             ItemKind::Struct(variant_data, _) => {
-                if attr_by_name(&item.attrs, "repr").is_some() {
+                if item.attrs.iter().any(|attr| attr.has_name(sym::repr)) {
                     return;
                 }
 

src/tools/clippy/clippy_lints/src/exit.rs

@@ -28,21 +28,19 @@ declare_lint_pass!(Exit => [EXIT]);
 impl<'tcx> LateLintPass<'tcx> for Exit {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
         if_chain! {
-            if let ExprKind::Call(ref path_expr, ref _args) = e.kind;
+            if let ExprKind::Call(path_expr, _args) = e.kind;
             if let ExprKind::Path(ref path) = path_expr.kind;
             if let Some(def_id) = cx.qpath_res(path, path_expr.hir_id).opt_def_id();
             if match_def_path(cx, def_id, &paths::EXIT);
-            then {
             let parent = cx.tcx.hir().get_parent_item(e.hir_id);
-                if let Some(Node::Item(Item{kind: ItemKind::Fn(..), ..})) = cx.tcx.hir().find(parent) {
+            if let Some(Node::Item(Item{kind: ItemKind::Fn(..), ..})) = cx.tcx.hir().find(parent);
             // If the next item up is a function we check if it is an entry point
             // and only then emit a linter warning
             let def_id = cx.tcx.hir().local_def_id(parent);
-                    if !is_entrypoint_fn(cx, def_id.to_def_id()) {
+            if !is_entrypoint_fn(cx, def_id.to_def_id());
+            then {
                 span_lint(cx, EXIT, e.span, "usage of `process::exit`");
             }
         }
     }
-        }
-    }
 }

src/tools/clippy/clippy_lints/src/explicit_write.rs

@@ -34,11 +34,11 @@ impl<'tcx> LateLintPass<'tcx> for ExplicitWrite {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
             // match call to unwrap
-            if let ExprKind::MethodCall(ref unwrap_fun, _, ref unwrap_args, _) = expr.kind;
+            if let ExprKind::MethodCall(unwrap_fun, _, unwrap_args, _) = expr.kind;
             if unwrap_fun.ident.name == sym::unwrap;
             // match call to write_fmt
             if !unwrap_args.is_empty();
-            if let ExprKind::MethodCall(ref write_fun, _, write_args, _) =
+            if let ExprKind::MethodCall(write_fun, _, write_args, _) =
                 unwrap_args[0].kind;
             if write_fun.ident.name == sym!(write_fmt);
             // match calls to std::io::stdout() / std::io::stderr ()
@@ -135,10 +135,10 @@ fn write_output_string(write_args: &[Expr<'_>]) -> Option<String> {
     if_chain! {
         // Obtain the string that should be printed
         if write_args.len() > 1;
-        if let ExprKind::Call(_, ref output_args) = write_args[1].kind;
+        if let ExprKind::Call(_, output_args) = write_args[1].kind;
         if !output_args.is_empty();
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref output_string_expr) = output_args[0].kind;
-        if let ExprKind::Array(ref string_exprs) = output_string_expr.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, output_string_expr) = output_args[0].kind;
+        if let ExprKind::Array(string_exprs) = output_string_expr.kind;
         // we only want to provide an automatic suggestion for simple (non-format) strings
         if string_exprs.len() == 1;
         if let ExprKind::Lit(ref lit) = string_exprs[0].kind;

src/tools/clippy/clippy_lints/src/fallible_impl_from.rs

@@ -81,8 +81,8 @@ fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, impl_items: &[h
         fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
             // check for `begin_panic`
             if_chain! {
-                if let ExprKind::Call(ref func_expr, _) = expr.kind;
-                if let ExprKind::Path(QPath::Resolved(_, ref path)) = func_expr.kind;
+                if let ExprKind::Call(func_expr, _) = expr.kind;
+                if let ExprKind::Path(QPath::Resolved(_, path)) = func_expr.kind;
                 if let Some(path_def_id) = path.res.opt_def_id();
                 if match_panic_def_id(self.lcx, path_def_id);
                 if is_expn_of(expr.span, "unreachable").is_none();

src/tools/clippy/clippy_lints/src/float_equality_without_abs.rs

@@ -48,7 +48,7 @@ impl<'tcx> LateLintPass<'tcx> for FloatEqualityWithoutAbs {
         let rhs;
 
         // check if expr is a binary expression with a lt or gt operator
-        if let ExprKind::Binary(op, ref left, ref right) = expr.kind {
+        if let ExprKind::Binary(op, left, right) = expr.kind {
             match op.node {
                 BinOpKind::Lt => {
                     lhs = left;
@@ -88,8 +88,8 @@ impl<'tcx> LateLintPass<'tcx> for FloatEqualityWithoutAbs {
             if let ty::Float(_) = t_val_r.kind();
 
             then {
-                let sug_l = sugg::Sugg::hir(cx, &val_l, "..");
-                let sug_r = sugg::Sugg::hir(cx, &val_r, "..");
+                let sug_l = sugg::Sugg::hir(cx, val_l, "..");
+                let sug_r = sugg::Sugg::hir(cx, val_r, "..");
                 // format the suggestion
                 let suggestion = format!("{}.abs()", sugg::make_assoc(AssocOp::Subtract, &sug_l, &sug_r).maybe_par());
                 // spans the lint

src/tools/clippy/clippy_lints/src/float_literal.rs

@@ -61,8 +61,8 @@ declare_lint_pass!(FloatLiteral => [EXCESSIVE_PRECISION, LOSSY_FLOAT_LITERAL]);
 
 impl<'tcx> LateLintPass<'tcx> for FloatLiteral {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
-        if_chain! {
         let ty = cx.typeck_results().expr_ty(expr);
+        if_chain! {
             if let ty::Float(fty) = *ty.kind();
             if let hir::ExprKind::Lit(ref lit) = expr.kind;
             if let LitKind::Float(sym, lit_float_ty) = lit.node;

src/tools/clippy/clippy_lints/src/floating_point_arithmetic.rs

@@ -131,7 +131,7 @@ fn prepare_receiver_sugg<'a>(cx: &LateContext<'_>, mut expr: &'a Expr<'a>) -> Su
     let mut suggestion = Sugg::hir(cx, expr, "..");
 
     if let ExprKind::Unary(UnOp::Neg, inner_expr) = &expr.kind {
-        expr = &inner_expr;
+        expr = inner_expr;
     }
 
     if_chain! {
@@ -313,8 +313,8 @@ fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
                     Spanned {
                         node: BinOpKind::Add, ..
                     },
-                    ref lhs,
-                    ref rhs,
+                    lhs,
+                    rhs,
                 ) = parent.kind
                 {
                     let other_addend = if lhs.hir_id == expr.hir_id { rhs } else { lhs };
@@ -329,7 +329,7 @@ fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
                             "{}.mul_add({}, {})",
                             Sugg::hir(cx, &args[0], ".."),
                             Sugg::hir(cx, &args[0], ".."),
-                            Sugg::hir(cx, &other_addend, ".."),
+                            Sugg::hir(cx, other_addend, ".."),
                         ),
                         Applicability::MachineApplicable,
                     );
@@ -356,18 +356,18 @@ fn detect_hypot(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<String> {
         Spanned {
             node: BinOpKind::Add, ..
         },
-        ref add_lhs,
-        ref add_rhs,
+        add_lhs,
+        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 let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, lmul_lhs, lmul_rhs) = add_lhs.kind;
+            if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, rmul_lhs, rmul_rhs) = add_rhs.kind;
             if eq_expr_value(cx, lmul_lhs, lmul_rhs);
             if eq_expr_value(cx, rmul_lhs, rmul_rhs);
             then {
-                return Some(format!("{}.hypot({})", Sugg::hir(cx, &lmul_lhs, ".."), Sugg::hir(cx, &rmul_lhs, "..")));
+                return Some(format!("{}.hypot({})", Sugg::hir(cx, lmul_lhs, ".."), Sugg::hir(cx, rmul_lhs, "..")));
             }
         }
 
@@ -376,13 +376,13 @@ fn detect_hypot(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<String> {
             if let ExprKind::MethodCall(
                 PathSegment { ident: lmethod_name, .. },
                 ref _lspan,
-                ref largs,
+                largs,
                 _
             ) = add_lhs.kind;
             if let ExprKind::MethodCall(
                 PathSegment { ident: rmethod_name, .. },
                 ref _rspan,
-                ref rargs,
+                rargs,
                 _
             ) = add_rhs.kind;
             if lmethod_name.as_str() == "powi" && rmethod_name.as_str() == "powi";
@@ -416,11 +416,11 @@ fn check_hypot(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
 // and suggest usage of `x.exp_m1() - (y - 1)` instead
 fn check_expm1(cx: &LateContext<'_>, expr: &Expr<'_>) {
     if_chain! {
-        if let ExprKind::Binary(Spanned { node: BinOpKind::Sub, .. }, ref lhs, ref rhs) = expr.kind;
+        if let ExprKind::Binary(Spanned { node: BinOpKind::Sub, .. }, lhs, rhs) = expr.kind;
         if cx.typeck_results().expr_ty(lhs).is_floating_point();
         if let Some((value, _)) = constant(cx, cx.typeck_results(), rhs);
         if F32(1.0) == value || F64(1.0) == value;
-        if let ExprKind::MethodCall(ref path, _, ref method_args, _) = lhs.kind;
+        if let ExprKind::MethodCall(path, _, method_args, _) = lhs.kind;
         if cx.typeck_results().expr_ty(&method_args[0]).is_floating_point();
         if path.ident.name.as_str() == "exp";
         then {
@@ -442,7 +442,7 @@ fn check_expm1(cx: &LateContext<'_>, expr: &Expr<'_>) {
 
 fn is_float_mul_expr<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<(&'a Expr<'a>, &'a Expr<'a>)> {
     if_chain! {
-        if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref lhs, ref rhs) = &expr.kind;
+        if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, lhs, rhs) = &expr.kind;
         if cx.typeck_results().expr_ty(lhs).is_floating_point();
         if cx.typeck_results().expr_ty(rhs).is_floating_point();
         then {
@@ -604,8 +604,8 @@ 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;
+        if let ExprKind::MethodCall(PathSegment { ident: method_name_a, .. }, _, args_a, _) = expr_a.kind;
+        if let ExprKind::MethodCall(PathSegment { ident: method_name_b, .. }, _, args_b, _) = expr_b.kind;
         then {
             return method_name_a.as_str() == method_name_b.as_str() &&
                 args_a.len() == args_b.len() &&
@@ -630,8 +630,8 @@ fn check_log_division(cx: &LateContext<'_>, expr: &Expr<'_>) {
             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;
+        if let ExprKind::MethodCall(_, _, largs, _) = lhs.kind;
+        if let ExprKind::MethodCall(_, _, rargs, _) = rhs.kind;
         then {
             span_lint_and_sugg(
                 cx,
@@ -675,7 +675,7 @@ fn check_radians(cx: &LateContext<'_>, expr: &Expr<'_>) {
                     expr.span,
                     "conversion to degrees can be done more accurately",
                     "consider using",
-                    format!("{}.to_degrees()", Sugg::hir(cx, &mul_lhs, "..")),
+                    format!("{}.to_degrees()", Sugg::hir(cx, mul_lhs, "..")),
                     Applicability::MachineApplicable,
                 );
             } else if
@@ -688,7 +688,7 @@ fn check_radians(cx: &LateContext<'_>, expr: &Expr<'_>) {
                     expr.span,
                     "conversion to radians can be done more accurately",
                     "consider using",
-                    format!("{}.to_radians()", Sugg::hir(cx, &mul_lhs, "..")),
+                    format!("{}.to_radians()", Sugg::hir(cx, mul_lhs, "..")),
                     Applicability::MachineApplicable,
                 );
             }
@@ -698,7 +698,7 @@ fn check_radians(cx: &LateContext<'_>, expr: &Expr<'_>) {
 
 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 {
+        if let ExprKind::MethodCall(path, _, args, _) = &expr.kind {
             let recv_ty = cx.typeck_results().expr_ty(&args[0]);
 
             if recv_ty.is_floating_point() {

src/tools/clippy/clippy_lints/src/format.rs

@@ -78,8 +78,8 @@ fn span_useless_format<T: LintContext>(cx: &T, span: Span, help: &str, mut sugg:
 
 fn on_argumentv1_new<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arms: &'tcx [Arm<'_>]) -> Option<String> {
     if_chain! {
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref format_args) = expr.kind;
-        if let ExprKind::Array(ref elems) = arms[0].body.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, format_args) = expr.kind;
+        if let ExprKind::Array(elems) = arms[0].body.kind;
         if elems.len() == 1;
         if let Some(args) = match_function_call(cx, &elems[0], &paths::FMT_ARGUMENTV1_NEW);
         // matches `core::fmt::Display::fmt`
@@ -88,10 +88,10 @@ fn on_argumentv1_new<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arms: &
         if let Some(did) = cx.qpath_res(qpath, args[1].hir_id).opt_def_id();
         if match_def_path(cx, did, &paths::DISPLAY_FMT_METHOD);
         // check `(arg0,)` in match block
-        if let PatKind::Tuple(ref pats, None) = arms[0].pat.kind;
+        if let PatKind::Tuple(pats, None) = arms[0].pat.kind;
         if pats.len() == 1;
         then {
-            let ty = cx.typeck_results().pat_ty(&pats[0]).peel_refs();
+            let ty = cx.typeck_results().pat_ty(pats[0]).peel_refs();
             if *ty.kind() != rustc_middle::ty::Str && !is_type_diagnostic_item(cx, ty, sym::string_type) {
                 return None;
             }
@@ -101,7 +101,7 @@ fn on_argumentv1_new<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arms: &
                 }
             } else {
                 let snip = snippet(cx, format_args.span, "<arg>");
-                if let ExprKind::MethodCall(ref path, _, _, _) = format_args.kind {
+                if let ExprKind::MethodCall(path, _, _, _) = format_args.kind {
                     if path.ident.name == sym!(to_string) {
                         return Some(format!("{}", snip));
                     }
@@ -120,16 +120,16 @@ fn on_new_v1<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Strin
         if let Some(args) = match_function_call(cx, expr, &paths::FMT_ARGUMENTS_NEW_V1);
         if args.len() == 2;
         // Argument 1 in `new_v1()`
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arr) = args[0].kind;
-        if let ExprKind::Array(ref pieces) = arr.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
+        if let ExprKind::Array(pieces) = arr.kind;
         if pieces.len() == 1;
         if let ExprKind::Lit(ref lit) = pieces[0].kind;
         if let LitKind::Str(ref s, _) = lit.node;
         // Argument 2 in `new_v1()`
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arg1) = args[1].kind;
-        if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
+        if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
         if arms.len() == 1;
-        if let ExprKind::Tup(ref tup) = matchee.kind;
+        if let ExprKind::Tup(tup) = matchee.kind;
         then {
             // `format!("foo")` expansion contains `match () { () => [], }`
             if tup.is_empty() {
@@ -152,16 +152,16 @@ fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<S
         if args.len() == 3;
         if check_unformatted(&args[2]);
         // Argument 1 in `new_v1_formatted()`
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arr) = args[0].kind;
-        if let ExprKind::Array(ref pieces) = arr.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, arr) = args[0].kind;
+        if let ExprKind::Array(pieces) = arr.kind;
         if pieces.len() == 1;
         if let ExprKind::Lit(ref lit) = pieces[0].kind;
         if let LitKind::Str(..) = lit.node;
         // Argument 2 in `new_v1_formatted()`
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref arg1) = args[1].kind;
-        if let ExprKind::Match(ref matchee, ref arms, MatchSource::Normal) = arg1.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, arg1) = args[1].kind;
+        if let ExprKind::Match(matchee, arms, MatchSource::Normal) = arg1.kind;
         if arms.len() == 1;
-        if let ExprKind::Tup(ref tup) = matchee.kind;
+        if let ExprKind::Tup(tup) = matchee.kind;
         then {
             return on_argumentv1_new(cx, &tup[0], arms);
         }
@@ -182,14 +182,14 @@ fn on_new_v1_fmt<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<S
 /// ```
 fn check_unformatted(expr: &Expr<'_>) -> bool {
     if_chain! {
-        if let ExprKind::AddrOf(BorrowKind::Ref, _, ref expr) = expr.kind;
-        if let ExprKind::Array(ref exprs) = expr.kind;
+        if let ExprKind::AddrOf(BorrowKind::Ref, _, expr) = expr.kind;
+        if let ExprKind::Array(exprs) = expr.kind;
         if exprs.len() == 1;
         // struct `core::fmt::rt::v1::Argument`
-        if let ExprKind::Struct(_, ref fields, _) = exprs[0].kind;
+        if let ExprKind::Struct(_, fields, _) = exprs[0].kind;
         if let Some(format_field) = fields.iter().find(|f| f.ident.name == sym::format);
         // struct `core::fmt::rt::v1::FormatSpec`
-        if let ExprKind::Struct(_, ref fields, _) = format_field.expr.kind;
+        if let ExprKind::Struct(_, fields, _) = format_field.expr.kind;
         if let Some(precision_field) = fields.iter().find(|f| f.ident.name == sym::precision);
         if let ExprKind::Path(ref precision_path) = precision_field.expr.kind;
         if last_path_segment(precision_path).ident.name == sym::Implied;

src/tools/clippy/clippy_lints/src/formatting.rs

@@ -217,9 +217,8 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
         if let Some(else_snippet) = snippet_opt(cx, else_span);
         if let Some(else_pos) = else_snippet.find("else");
         if else_snippet[else_pos..].contains('\n');
-        let else_desc = if is_if(else_) { "if" } else { "{..}" };
-
         then {
+            let else_desc = if is_if(else_) { "if" } else { "{..}" };
             span_lint_and_note(
                 cx,
                 SUSPICIOUS_ELSE_FORMATTING,

src/tools/clippy/clippy_lints/src/functions.rs

@@ -1,738 +0,0 @@
-use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_then};
-use clippy_utils::source::{snippet, snippet_opt};
-use clippy_utils::ty::{is_must_use_ty, is_type_diagnostic_item, type_is_unsafe_function};
-use clippy_utils::{
-    attr_by_name, attrs::is_proc_macro, is_trait_impl_item, iter_input_pats, match_def_path, must_use_attr,
-    path_to_local, return_ty, trait_ref_of_method,
-};
-use if_chain::if_chain;
-use rustc_ast::ast::Attribute;
-use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::Applicability;
-use rustc_hir as hir;
-use rustc_hir::intravisit;
-use rustc_hir::{def::Res, def_id::DefId, QPath};
-use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::hir::map::Map;
-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::sym;
-use rustc_target::spec::abi::Abi;
-use rustc_typeck::hir_ty_to_ty;
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for functions with too many parameters.
-    ///
-    /// **Why is this bad?** Functions with lots of parameters are considered bad
-    /// style and reduce readability (“what does the 5th parameter mean?”). Consider
-    /// grouping some parameters into a new type.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// # struct Color;
-    /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b: f32) {
-    ///     // ..
-    /// }
-    /// ```
-    pub TOO_MANY_ARGUMENTS,
-    complexity,
-    "functions with too many arguments"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for functions with a large amount of lines.
-    ///
-    /// **Why is this bad?** Functions with a lot of lines are harder to understand
-    /// due to having to look at a larger amount of code to understand what the
-    /// function is doing. Consider splitting the body of the function into
-    /// multiple functions.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
-    /// ```rust
-    /// fn im_too_long() {
-    ///     println!("");
-    ///     // ... 100 more LoC
-    ///     println!("");
-    /// }
-    /// ```
-    pub TOO_MANY_LINES,
-    pedantic,
-    "functions with too many lines"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for public functions that dereference raw pointer
-    /// arguments but are not marked unsafe.
-    ///
-    /// **Why is this bad?** The function should probably be marked `unsafe`, since
-    /// for an arbitrary raw pointer, there is no way of telling for sure if it is
-    /// valid.
-    ///
-    /// **Known problems:**
-    ///
-    /// * It does not check functions recursively so if the pointer is passed to a
-    /// private non-`unsafe` function which does the dereferencing, the lint won't
-    /// trigger.
-    /// * It only checks for arguments whose type are raw pointers, not raw pointers
-    /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
-    /// `some_argument.get_raw_ptr()`).
-    ///
-    /// **Example:**
-    /// ```rust,ignore
-    /// // Bad
-    /// pub fn foo(x: *const u8) {
-    ///     println!("{}", unsafe { *x });
-    /// }
-    ///
-    /// // Good
-    /// pub unsafe fn foo(x: *const u8) {
-    ///     println!("{}", unsafe { *x });
-    /// }
-    /// ```
-    pub NOT_UNSAFE_PTR_ARG_DEREF,
-    correctness,
-    "public functions dereferencing raw pointer arguments but not marked `unsafe`"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for a [`#[must_use]`] attribute on
-    /// unit-returning functions and methods.
-    ///
-    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
-    ///
-    /// **Why is this bad?** Unit values are useless. The attribute is likely
-    /// a remnant of a refactoring that removed the return type.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Examples:**
-    /// ```rust
-    /// #[must_use]
-    /// fn useless() { }
-    /// ```
-    pub MUST_USE_UNIT,
-    style,
-    "`#[must_use]` attribute on a unit-returning function / method"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for a [`#[must_use]`] attribute without
-    /// further information on functions and methods that return a type already
-    /// marked as `#[must_use]`.
-    ///
-    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
-    ///
-    /// **Why is this bad?** The attribute isn't needed. Not using the result
-    /// will already be reported. Alternatively, one can add some text to the
-    /// attribute to improve the lint message.
-    ///
-    /// **Known problems:** None.
-    ///
-    /// **Examples:**
-    /// ```rust
-    /// #[must_use]
-    /// fn double_must_use() -> Result<(), ()> {
-    ///     unimplemented!();
-    /// }
-    /// ```
-    pub DOUBLE_MUST_USE,
-    style,
-    "`#[must_use]` attribute on a `#[must_use]`-returning function / method"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for public functions that have no
-    /// [`#[must_use]`] attribute, but return something not already marked
-    /// must-use, have no mutable arg and mutate no statics.
-    ///
-    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
-    ///
-    /// **Why is this bad?** Not bad at all, this lint just shows places where
-    /// you could add the attribute.
-    ///
-    /// **Known problems:** The lint only checks the arguments for mutable
-    /// types without looking if they are actually changed. On the other hand,
-    /// it also ignores a broad range of potentially interesting side effects,
-    /// because we cannot decide whether the programmer intends the function to
-    /// be called for the side effect or the result. Expect many false
-    /// positives. At least we don't lint if the result type is unit or already
-    /// `#[must_use]`.
-    ///
-    /// **Examples:**
-    /// ```rust
-    /// // this could be annotated with `#[must_use]`.
-    /// fn id<T>(t: T) -> T { t }
-    /// ```
-    pub MUST_USE_CANDIDATE,
-    pedantic,
-    "function or method that could take a `#[must_use]` attribute"
-}
-
-declare_clippy_lint! {
-    /// **What it does:** Checks for public functions that return a `Result`
-    /// with an `Err` type of `()`. It suggests using a custom type that
-    /// implements [`std::error::Error`].
-    ///
-    /// **Why is this bad?** Unit does not implement `Error` and carries no
-    /// further information about what went wrong.
-    ///
-    /// **Known problems:** Of course, this lint assumes that `Result` is used
-    /// for a fallible operation (which is after all the intended use). However
-    /// code may opt to (mis)use it as a basic two-variant-enum. In that case,
-    /// the suggestion is misguided, and the code should use a custom enum
-    /// instead.
-    ///
-    /// **Examples:**
-    /// ```rust
-    /// pub fn read_u8() -> Result<u8, ()> { Err(()) }
-    /// ```
-    /// should become
-    /// ```rust,should_panic
-    /// use std::fmt;
-    ///
-    /// #[derive(Debug)]
-    /// pub struct EndOfStream;
-    ///
-    /// impl fmt::Display for EndOfStream {
-    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    ///         write!(f, "End of Stream")
-    ///     }
-    /// }
-    ///
-    /// impl std::error::Error for EndOfStream { }
-    ///
-    /// pub fn read_u8() -> Result<u8, EndOfStream> { Err(EndOfStream) }
-    ///# fn main() {
-    ///#     read_u8().unwrap();
-    ///# }
-    /// ```
-    ///
-    /// Note that there are crates that simplify creating the error type, e.g.
-    /// [`thiserror`](https://docs.rs/thiserror).
-    pub RESULT_UNIT_ERR,
-    style,
-    "public function returning `Result` with an `Err` type of `()`"
-}
-
-#[derive(Copy, Clone)]
-pub struct Functions {
-    threshold: u64,
-    max_lines: u64,
-}
-
-impl Functions {
-    pub fn new(threshold: u64, max_lines: u64) -> Self {
-        Self { threshold, max_lines }
-    }
-}
-
-impl_lint_pass!(Functions => [
-    TOO_MANY_ARGUMENTS,
-    TOO_MANY_LINES,
-    NOT_UNSAFE_PTR_ARG_DEREF,
-    MUST_USE_UNIT,
-    DOUBLE_MUST_USE,
-    MUST_USE_CANDIDATE,
-    RESULT_UNIT_ERR,
-]);
-
-impl<'tcx> LateLintPass<'tcx> for Functions {
-    fn check_fn(
-        &mut self,
-        cx: &LateContext<'tcx>,
-        kind: intravisit::FnKind<'tcx>,
-        decl: &'tcx hir::FnDecl<'_>,
-        body: &'tcx hir::Body<'_>,
-        span: Span,
-        hir_id: hir::HirId,
-    ) {
-        let unsafety = match kind {
-            intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _) => unsafety,
-            intravisit::FnKind::Method(_, sig, _) => sig.header.unsafety,
-            intravisit::FnKind::Closure => return,
-        };
-
-        // don't warn for implementations, it's not their fault
-        if !is_trait_impl_item(cx, hir_id) {
-            // don't lint extern functions decls, it's not their fault either
-            match kind {
-                intravisit::FnKind::Method(
-                    _,
-                    &hir::FnSig {
-                        header: hir::FnHeader { abi: Abi::Rust, .. },
-                        ..
-                    },
-                    _,
-                )
-                | intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _) => {
-                    self.check_arg_number(cx, decl, span.with_hi(decl.output.span().hi()))
-                },
-                _ => {},
-            }
-        }
-
-        Self::check_raw_ptr(cx, unsafety, decl, body, hir_id);
-        self.check_line_number(cx, span, body);
-    }
-
-    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
-        let attrs = cx.tcx.hir().attrs(item.hir_id());
-        let attr = must_use_attr(attrs);
-        if let hir::ItemKind::Fn(ref sig, ref _generics, ref body_id) = item.kind {
-            let is_public = cx.access_levels.is_exported(item.hir_id());
-            let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
-            if is_public {
-                check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
-            }
-            if let Some(attr) = attr {
-                check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
-                return;
-            }
-            if is_public && !is_proc_macro(cx.sess(), attrs) && attr_by_name(attrs, "no_mangle").is_none() {
-                check_must_use_candidate(
-                    cx,
-                    &sig.decl,
-                    cx.tcx.hir().body(*body_id),
-                    item.span,
-                    item.hir_id(),
-                    item.span.with_hi(sig.decl.output.span().hi()),
-                    "this function could have a `#[must_use]` attribute",
-                );
-            }
-        }
-    }
-
-    fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
-        if let hir::ImplItemKind::Fn(ref sig, ref body_id) = item.kind {
-            let is_public = cx.access_levels.is_exported(item.hir_id());
-            let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
-            if is_public && trait_ref_of_method(cx, item.hir_id()).is_none() {
-                check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
-            }
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
-            let attr = must_use_attr(attrs);
-            if let Some(attr) = attr {
-                check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
-            } else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.hir_id()).is_none()
-            {
-                check_must_use_candidate(
-                    cx,
-                    &sig.decl,
-                    cx.tcx.hir().body(*body_id),
-                    item.span,
-                    item.hir_id(),
-                    item.span.with_hi(sig.decl.output.span().hi()),
-                    "this method could have a `#[must_use]` attribute",
-                );
-            }
-        }
-    }
-
-    fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
-        if let hir::TraitItemKind::Fn(ref sig, ref eid) = item.kind {
-            // don't lint extern functions decls, it's not their fault
-            if sig.header.abi == Abi::Rust {
-                self.check_arg_number(cx, &sig.decl, item.span.with_hi(sig.decl.output.span().hi()));
-            }
-            let is_public = cx.access_levels.is_exported(item.hir_id());
-            let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
-            if is_public {
-                check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
-            }
-
-            let attrs = cx.tcx.hir().attrs(item.hir_id());
-            let attr = must_use_attr(attrs);
-            if let Some(attr) = attr {
-                check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
-            }
-            if let hir::TraitFn::Provided(eid) = *eid {
-                let body = cx.tcx.hir().body(eid);
-                Self::check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.hir_id());
-
-                if attr.is_none() && is_public && !is_proc_macro(cx.sess(), attrs) {
-                    check_must_use_candidate(
-                        cx,
-                        &sig.decl,
-                        body,
-                        item.span,
-                        item.hir_id(),
-                        item.span.with_hi(sig.decl.output.span().hi()),
-                        "this method could have a `#[must_use]` attribute",
-                    );
-                }
-            }
-        }
-    }
-}
-
-impl<'tcx> Functions {
-    fn check_arg_number(self, cx: &LateContext<'_>, decl: &hir::FnDecl<'_>, fn_span: Span) {
-        let args = decl.inputs.len() as u64;
-        if args > self.threshold {
-            span_lint(
-                cx,
-                TOO_MANY_ARGUMENTS,
-                fn_span,
-                &format!("this function has too many arguments ({}/{})", args, self.threshold),
-            );
-        }
-    }
-
-    fn check_line_number(self, cx: &LateContext<'_>, span: Span, body: &'tcx hir::Body<'_>) {
-        if in_external_macro(cx.sess(), span) {
-            return;
-        }
-
-        let code_snippet = snippet(cx, body.value.span, "..");
-        let mut line_count: u64 = 0;
-        let mut in_comment = false;
-        let mut code_in_line;
-
-        // Skip the surrounding function decl.
-        let start_brace_idx = code_snippet.find('{').map_or(0, |i| i + 1);
-        let end_brace_idx = code_snippet.rfind('}').unwrap_or_else(|| code_snippet.len());
-        let function_lines = code_snippet[start_brace_idx..end_brace_idx].lines();
-
-        for mut line in function_lines {
-            code_in_line = false;
-            loop {
-                line = line.trim_start();
-                if line.is_empty() {
-                    break;
-                }
-                if in_comment {
-                    if let Some(i) = line.find("*/") {
-                        line = &line[i + 2..];
-                        in_comment = false;
-                        continue;
-                    }
-                } else {
-                    let multi_idx = line.find("/*").unwrap_or_else(|| line.len());
-                    let single_idx = line.find("//").unwrap_or_else(|| line.len());
-                    code_in_line |= multi_idx > 0 && single_idx > 0;
-                    // Implies multi_idx is below line.len()
-                    if multi_idx < single_idx {
-                        line = &line[multi_idx + 2..];
-                        in_comment = true;
-                        continue;
-                    }
-                }
-                break;
-            }
-            if code_in_line {
-                line_count += 1;
-            }
-        }
-
-        if line_count > self.max_lines {
-            span_lint(
-                cx,
-                TOO_MANY_LINES,
-                span,
-                &format!("this function has too many lines ({}/{})", line_count, self.max_lines),
-            )
-        }
-    }
-
-    fn check_raw_ptr(
-        cx: &LateContext<'tcx>,
-        unsafety: hir::Unsafety,
-        decl: &'tcx hir::FnDecl<'_>,
-        body: &'tcx hir::Body<'_>,
-        hir_id: hir::HirId,
-    ) {
-        let expr = &body.value;
-        if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(hir_id) {
-            let raw_ptrs = iter_input_pats(decl, body)
-                .zip(decl.inputs.iter())
-                .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
-                .collect::<FxHashSet<_>>();
-
-            if !raw_ptrs.is_empty() {
-                let typeck_results = cx.tcx.typeck_body(body.id());
-                let mut v = DerefVisitor {
-                    cx,
-                    ptrs: raw_ptrs,
-                    typeck_results,
-                };
-
-                intravisit::walk_expr(&mut v, expr);
-            }
-        }
-    }
-}
-
-fn check_result_unit_err(cx: &LateContext<'_>, decl: &hir::FnDecl<'_>, item_span: Span, fn_header_span: Span) {
-    if_chain! {
-        if !in_external_macro(cx.sess(), item_span);
-        if let hir::FnRetTy::Return(ref ty) = decl.output;
-        let ty = hir_ty_to_ty(cx.tcx, ty);
-        if is_type_diagnostic_item(cx, ty, sym::result_type);
-        if let ty::Adt(_, substs) = ty.kind();
-        let err_ty = substs.type_at(1);
-        if err_ty.is_unit();
-        then {
-            span_lint_and_help(
-                cx,
-                RESULT_UNIT_ERR,
-                fn_header_span,
-                "this returns a `Result<_, ()>",
-                None,
-                "use a custom Error type instead",
-            );
-        }
-    }
-}
-
-fn check_needless_must_use(
-    cx: &LateContext<'_>,
-    decl: &hir::FnDecl<'_>,
-    item_id: hir::HirId,
-    item_span: Span,
-    fn_header_span: Span,
-    attr: &Attribute,
-) {
-    if in_external_macro(cx.sess(), item_span) {
-        return;
-    }
-    if returns_unit(decl) {
-        span_lint_and_then(
-            cx,
-            MUST_USE_UNIT,
-            fn_header_span,
-            "this unit-returning function has a `#[must_use]` attribute",
-            |diag| {
-                diag.span_suggestion(
-                    attr.span,
-                    "remove the attribute",
-                    "".into(),
-                    Applicability::MachineApplicable,
-                );
-            },
-        );
-    } else if !attr.value_str().is_some() && is_must_use_ty(cx, return_ty(cx, item_id)) {
-        span_lint_and_help(
-            cx,
-            DOUBLE_MUST_USE,
-            fn_header_span,
-            "this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`",
-            None,
-            "either add some descriptive text or remove the attribute",
-        );
-    }
-}
-
-fn check_must_use_candidate<'tcx>(
-    cx: &LateContext<'tcx>,
-    decl: &'tcx hir::FnDecl<'_>,
-    body: &'tcx hir::Body<'_>,
-    item_span: Span,
-    item_id: hir::HirId,
-    fn_span: Span,
-    msg: &str,
-) {
-    if has_mutable_arg(cx, body)
-        || mutates_static(cx, body)
-        || in_external_macro(cx.sess(), item_span)
-        || returns_unit(decl)
-        || !cx.access_levels.is_exported(item_id)
-        || is_must_use_ty(cx, return_ty(cx, item_id))
-    {
-        return;
-    }
-    span_lint_and_then(cx, MUST_USE_CANDIDATE, fn_span, msg, |diag| {
-        if let Some(snippet) = snippet_opt(cx, fn_span) {
-            diag.span_suggestion(
-                fn_span,
-                "add the attribute",
-                format!("#[must_use] {}", snippet),
-                Applicability::MachineApplicable,
-            );
-        }
-    });
-}
-
-fn returns_unit(decl: &hir::FnDecl<'_>) -> bool {
-    match decl.output {
-        hir::FnRetTy::DefaultReturn(_) => true,
-        hir::FnRetTy::Return(ref ty) => match ty.kind {
-            hir::TyKind::Tup(ref tys) => tys.is_empty(),
-            hir::TyKind::Never => true,
-            _ => false,
-        },
-    }
-}
-
-fn has_mutable_arg(cx: &LateContext<'_>, body: &hir::Body<'_>) -> bool {
-    let mut tys = FxHashSet::default();
-    body.params.iter().any(|param| is_mutable_pat(cx, &param.pat, &mut tys))
-}
-
-fn is_mutable_pat(cx: &LateContext<'_>, pat: &hir::Pat<'_>, tys: &mut FxHashSet<DefId>) -> bool {
-    if let hir::PatKind::Wild = pat.kind {
-        return false; // ignore `_` patterns
-    }
-    if cx.tcx.has_typeck_results(pat.hir_id.owner.to_def_id()) {
-        is_mutable_ty(cx, &cx.tcx.typeck(pat.hir_id.owner).pat_ty(pat), pat.span, tys)
-    } else {
-        false
-    }
-}
-
-static KNOWN_WRAPPER_TYS: &[&[&str]] = &[&["alloc", "rc", "Rc"], &["std", "sync", "Arc"]];
-
-fn is_mutable_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span, tys: &mut FxHashSet<DefId>) -> bool {
-    match *ty.kind() {
-        // primitive types are never mutable
-        ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => false,
-        ty::Adt(ref adt, ref substs) => {
-            tys.insert(adt.did) && !ty.is_freeze(cx.tcx.at(span), cx.param_env)
-                || KNOWN_WRAPPER_TYS.iter().any(|path| match_def_path(cx, adt.did, path))
-                    && substs.types().any(|ty| is_mutable_ty(cx, ty, span, tys))
-        },
-        ty::Tuple(ref substs) => substs.types().any(|ty| is_mutable_ty(cx, ty, span, tys)),
-        ty::Array(ty, _) | ty::Slice(ty) => is_mutable_ty(cx, ty, span, tys),
-        ty::RawPtr(ty::TypeAndMut { ty, mutbl }) | ty::Ref(_, ty, mutbl) => {
-            mutbl == hir::Mutability::Mut || is_mutable_ty(cx, ty, span, tys)
-        },
-        // calling something constitutes a side effect, so return true on all callables
-        // also never calls need not be used, so return true for them, too
-        _ => true,
-    }
-}
-
-fn raw_ptr_arg(arg: &hir::Param<'_>, ty: &hir::Ty<'_>) -> Option<hir::HirId> {
-    if let (&hir::PatKind::Binding(_, id, _, _), &hir::TyKind::Ptr(_)) = (&arg.pat.kind, &ty.kind) {
-        Some(id)
-    } else {
-        None
-    }
-}
-
-struct DerefVisitor<'a, 'tcx> {
-    cx: &'a LateContext<'tcx>,
-    ptrs: FxHashSet<hir::HirId>,
-    typeck_results: &'a ty::TypeckResults<'tcx>,
-}
-
-impl<'a, 'tcx> intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
-
-    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
-        match expr.kind {
-            hir::ExprKind::Call(ref f, args) => {
-                let ty = self.typeck_results.expr_ty(f);
-
-                if type_is_unsafe_function(self.cx, ty) {
-                    for arg in args {
-                        self.check_arg(arg);
-                    }
-                }
-            },
-            hir::ExprKind::MethodCall(_, _, args, _) => {
-                let def_id = self.typeck_results.type_dependent_def_id(expr.hir_id).unwrap();
-                let base_type = self.cx.tcx.type_of(def_id);
-
-                if type_is_unsafe_function(self.cx, base_type) {
-                    for arg in args {
-                        self.check_arg(arg);
-                    }
-                }
-            },
-            hir::ExprKind::Unary(hir::UnOp::Deref, ref ptr) => self.check_arg(ptr),
-            _ => (),
-        }
-
-        intravisit::walk_expr(self, expr);
-    }
-
-    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
-        intravisit::NestedVisitorMap::None
-    }
-}
-
-impl<'a, 'tcx> DerefVisitor<'a, 'tcx> {
-    fn check_arg(&self, ptr: &hir::Expr<'_>) {
-        if let Some(id) = path_to_local(ptr) {
-            if self.ptrs.contains(&id) {
-                span_lint(
-                    self.cx,
-                    NOT_UNSAFE_PTR_ARG_DEREF,
-                    ptr.span,
-                    "this public function dereferences a raw pointer but is not marked `unsafe`",
-                );
-            }
-        }
-    }
-}
-
-struct StaticMutVisitor<'a, 'tcx> {
-    cx: &'a LateContext<'tcx>,
-    mutates_static: bool,
-}
-
-impl<'a, 'tcx> intravisit::Visitor<'tcx> for StaticMutVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
-
-    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
-        use hir::ExprKind::{AddrOf, Assign, AssignOp, Call, MethodCall};
-
-        if self.mutates_static {
-            return;
-        }
-        match expr.kind {
-            Call(_, args) | MethodCall(_, _, args, _) => {
-                let mut tys = FxHashSet::default();
-                for arg in args {
-                    if self.cx.tcx.has_typeck_results(arg.hir_id.owner.to_def_id())
-                        && is_mutable_ty(
-                            self.cx,
-                            self.cx.tcx.typeck(arg.hir_id.owner).expr_ty(arg),
-                            arg.span,
-                            &mut tys,
-                        )
-                        && is_mutated_static(arg)
-                    {
-                        self.mutates_static = true;
-                        return;
-                    }
-                    tys.clear();
-                }
-            },
-            Assign(ref target, ..) | AssignOp(_, ref target, _) | AddrOf(_, hir::Mutability::Mut, ref target) => {
-                self.mutates_static |= is_mutated_static(target)
-            },
-            _ => {},
-        }
-    }
-
-    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
-        intravisit::NestedVisitorMap::None
-    }
-}
-
-fn is_mutated_static(e: &hir::Expr<'_>) -> bool {
-    use hir::ExprKind::{Field, Index, Path};
-
-    match e.kind {
-        Path(QPath::Resolved(_, path)) => !matches!(path.res, Res::Local(_)),
-        Path(_) => true,
-        Field(ref inner, _) | Index(ref inner, _) => is_mutated_static(inner),
-        _ => false,
-    }
-}
-
-fn mutates_static<'tcx>(cx: &LateContext<'tcx>, body: &'tcx hir::Body<'_>) -> bool {
-    let mut v = StaticMutVisitor {
-        cx,
-        mutates_static: false,
-    };
-    intravisit::walk_expr(&mut v, &body.value);
-    v.mutates_static
-}

src/tools/clippy/clippy_lints/src/functions/mod.rs

@@ -0,0 +1,267 @@
+mod must_use;
+mod not_unsafe_ptr_arg_deref;
+mod result_unit_err;
+mod too_many_arguments;
+mod too_many_lines;
+
+use rustc_hir as hir;
+use rustc_hir::intravisit;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::Span;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for functions with too many parameters.
+    ///
+    /// **Why is this bad?** Functions with lots of parameters are considered bad
+    /// style and reduce readability (“what does the 5th parameter mean?”). Consider
+    /// grouping some parameters into a new type.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # struct Color;
+    /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b: f32) {
+    ///     // ..
+    /// }
+    /// ```
+    pub TOO_MANY_ARGUMENTS,
+    complexity,
+    "functions with too many arguments"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for functions with a large amount of lines.
+    ///
+    /// **Why is this bad?** Functions with a lot of lines are harder to understand
+    /// due to having to look at a larger amount of code to understand what the
+    /// function is doing. Consider splitting the body of the function into
+    /// multiple functions.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// fn im_too_long() {
+    ///     println!("");
+    ///     // ... 100 more LoC
+    ///     println!("");
+    /// }
+    /// ```
+    pub TOO_MANY_LINES,
+    pedantic,
+    "functions with too many lines"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for public functions that dereference raw pointer
+    /// arguments but are not marked `unsafe`.
+    ///
+    /// **Why is this bad?** The function should probably be marked `unsafe`, since
+    /// for an arbitrary raw pointer, there is no way of telling for sure if it is
+    /// valid.
+    ///
+    /// **Known problems:**
+    ///
+    /// * It does not check functions recursively so if the pointer is passed to a
+    /// private non-`unsafe` function which does the dereferencing, the lint won't
+    /// trigger.
+    /// * It only checks for arguments whose type are raw pointers, not raw pointers
+    /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
+    /// `some_argument.get_raw_ptr()`).
+    ///
+    /// **Example:**
+    /// ```rust,ignore
+    /// // Bad
+    /// pub fn foo(x: *const u8) {
+    ///     println!("{}", unsafe { *x });
+    /// }
+    ///
+    /// // Good
+    /// pub unsafe fn foo(x: *const u8) {
+    ///     println!("{}", unsafe { *x });
+    /// }
+    /// ```
+    pub NOT_UNSAFE_PTR_ARG_DEREF,
+    correctness,
+    "public functions dereferencing raw pointer arguments but not marked `unsafe`"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for a [`#[must_use]`] attribute on
+    /// unit-returning functions and methods.
+    ///
+    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
+    ///
+    /// **Why is this bad?** Unit values are useless. The attribute is likely
+    /// a remnant of a refactoring that removed the return type.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Examples:**
+    /// ```rust
+    /// #[must_use]
+    /// fn useless() { }
+    /// ```
+    pub MUST_USE_UNIT,
+    style,
+    "`#[must_use]` attribute on a unit-returning function / method"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for a [`#[must_use]`] attribute without
+    /// further information on functions and methods that return a type already
+    /// marked as `#[must_use]`.
+    ///
+    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
+    ///
+    /// **Why is this bad?** The attribute isn't needed. Not using the result
+    /// will already be reported. Alternatively, one can add some text to the
+    /// attribute to improve the lint message.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Examples:**
+    /// ```rust
+    /// #[must_use]
+    /// fn double_must_use() -> Result<(), ()> {
+    ///     unimplemented!();
+    /// }
+    /// ```
+    pub DOUBLE_MUST_USE,
+    style,
+    "`#[must_use]` attribute on a `#[must_use]`-returning function / method"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for public functions that have no
+    /// [`#[must_use]`] attribute, but return something not already marked
+    /// must-use, have no mutable arg and mutate no statics.
+    ///
+    /// [`#[must_use]`]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
+    ///
+    /// **Why is this bad?** Not bad at all, this lint just shows places where
+    /// you could add the attribute.
+    ///
+    /// **Known problems:** The lint only checks the arguments for mutable
+    /// types without looking if they are actually changed. On the other hand,
+    /// it also ignores a broad range of potentially interesting side effects,
+    /// because we cannot decide whether the programmer intends the function to
+    /// be called for the side effect or the result. Expect many false
+    /// positives. At least we don't lint if the result type is unit or already
+    /// `#[must_use]`.
+    ///
+    /// **Examples:**
+    /// ```rust
+    /// // this could be annotated with `#[must_use]`.
+    /// fn id<T>(t: T) -> T { t }
+    /// ```
+    pub MUST_USE_CANDIDATE,
+    pedantic,
+    "function or method that could take a `#[must_use]` attribute"
+}
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for public functions that return a `Result`
+    /// with an `Err` type of `()`. It suggests using a custom type that
+    /// implements `std::error::Error`.
+    ///
+    /// **Why is this bad?** Unit does not implement `Error` and carries no
+    /// further information about what went wrong.
+    ///
+    /// **Known problems:** Of course, this lint assumes that `Result` is used
+    /// for a fallible operation (which is after all the intended use). However
+    /// code may opt to (mis)use it as a basic two-variant-enum. In that case,
+    /// the suggestion is misguided, and the code should use a custom enum
+    /// instead.
+    ///
+    /// **Examples:**
+    /// ```rust
+    /// pub fn read_u8() -> Result<u8, ()> { Err(()) }
+    /// ```
+    /// should become
+    /// ```rust,should_panic
+    /// use std::fmt;
+    ///
+    /// #[derive(Debug)]
+    /// pub struct EndOfStream;
+    ///
+    /// impl fmt::Display for EndOfStream {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    ///         write!(f, "End of Stream")
+    ///     }
+    /// }
+    ///
+    /// impl std::error::Error for EndOfStream { }
+    ///
+    /// pub fn read_u8() -> Result<u8, EndOfStream> { Err(EndOfStream) }
+    ///# fn main() {
+    ///#     read_u8().unwrap();
+    ///# }
+    /// ```
+    ///
+    /// Note that there are crates that simplify creating the error type, e.g.
+    /// [`thiserror`](https://docs.rs/thiserror).
+    pub RESULT_UNIT_ERR,
+    style,
+    "public function returning `Result` with an `Err` type of `()`"
+}
+
+#[derive(Copy, Clone)]
+pub struct Functions {
+    too_many_arguments_threshold: u64,
+    too_many_lines_threshold: u64,
+}
+
+impl Functions {
+    pub fn new(too_many_arguments_threshold: u64, too_many_lines_threshold: u64) -> Self {
+        Self {
+            too_many_arguments_threshold,
+            too_many_lines_threshold,
+        }
+    }
+}
+
+impl_lint_pass!(Functions => [
+    TOO_MANY_ARGUMENTS,
+    TOO_MANY_LINES,
+    NOT_UNSAFE_PTR_ARG_DEREF,
+    MUST_USE_UNIT,
+    DOUBLE_MUST_USE,
+    MUST_USE_CANDIDATE,
+    RESULT_UNIT_ERR,
+]);
+
+impl<'tcx> LateLintPass<'tcx> for Functions {
+    fn check_fn(
+        &mut self,
+        cx: &LateContext<'tcx>,
+        kind: intravisit::FnKind<'tcx>,
+        decl: &'tcx hir::FnDecl<'_>,
+        body: &'tcx hir::Body<'_>,
+        span: Span,
+        hir_id: hir::HirId,
+    ) {
+        too_many_arguments::check_fn(cx, kind, decl, span, hir_id, self.too_many_arguments_threshold);
+        too_many_lines::check_fn(cx, span, body, self.too_many_lines_threshold);
+        not_unsafe_ptr_arg_deref::check_fn(cx, kind, decl, body, hir_id);
+    }
+
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
+        must_use::check_item(cx, item);
+        result_unit_err::check_item(cx, item);
+    }
+
+    fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
+        must_use::check_impl_item(cx, item);
+        result_unit_err::check_impl_item(cx, item);
+    }
+
+    fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
+        too_many_arguments::check_trait_item(cx, item, self.too_many_arguments_threshold);
+        not_unsafe_ptr_arg_deref::check_trait_item(cx, item);
+        must_use::check_trait_item(cx, item);
+        result_unit_err::check_trait_item(cx, item);
+    }
+}

src/tools/clippy/clippy_lints/src/functions/must_use.rs

@@ -0,0 +1,272 @@
+use rustc_ast::ast::Attribute;
+use rustc_errors::Applicability;
+use rustc_hir::def_id::DefIdSet;
+use rustc_hir::{self as hir, def::Res, intravisit, QPath};
+use rustc_lint::{LateContext, LintContext};
+use rustc_middle::{
+    hir::map::Map,
+    lint::in_external_macro,
+    ty::{self, Ty},
+};
+use rustc_span::{sym, Span};
+
+use clippy_utils::attrs::is_proc_macro;
+use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_then};
+use clippy_utils::source::snippet_opt;
+use clippy_utils::ty::is_must_use_ty;
+use clippy_utils::{match_def_path, must_use_attr, return_ty, trait_ref_of_method};
+
+use super::{DOUBLE_MUST_USE, MUST_USE_CANDIDATE, MUST_USE_UNIT};
+
+pub(super) fn check_item(cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
+    let attrs = cx.tcx.hir().attrs(item.hir_id());
+    let attr = must_use_attr(attrs);
+    if let hir::ItemKind::Fn(ref sig, ref _generics, ref body_id) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+        if let Some(attr) = attr {
+            check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
+            return;
+        } else if is_public && !is_proc_macro(cx.sess(), attrs) && !attrs.iter().any(|a| a.has_name(sym::no_mangle)) {
+            check_must_use_candidate(
+                cx,
+                sig.decl,
+                cx.tcx.hir().body(*body_id),
+                item.span,
+                item.hir_id(),
+                item.span.with_hi(sig.decl.output.span().hi()),
+                "this function could have a `#[must_use]` attribute",
+            );
+        }
+    }
+}
+
+pub(super) fn check_impl_item(cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
+    if let hir::ImplItemKind::Fn(ref sig, ref body_id) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+        let attrs = cx.tcx.hir().attrs(item.hir_id());
+        let attr = must_use_attr(attrs);
+        if let Some(attr) = attr {
+            check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
+        } else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.hir_id()).is_none() {
+            check_must_use_candidate(
+                cx,
+                sig.decl,
+                cx.tcx.hir().body(*body_id),
+                item.span,
+                item.hir_id(),
+                item.span.with_hi(sig.decl.output.span().hi()),
+                "this method could have a `#[must_use]` attribute",
+            );
+        }
+    }
+}
+
+pub(super) fn check_trait_item(cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
+    if let hir::TraitItemKind::Fn(ref sig, ref eid) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+
+        let attrs = cx.tcx.hir().attrs(item.hir_id());
+        let attr = must_use_attr(attrs);
+        if let Some(attr) = attr {
+            check_needless_must_use(cx, sig.decl, item.hir_id(), item.span, fn_header_span, attr);
+        } else if let hir::TraitFn::Provided(eid) = *eid {
+            let body = cx.tcx.hir().body(eid);
+            if attr.is_none() && is_public && !is_proc_macro(cx.sess(), attrs) {
+                check_must_use_candidate(
+                    cx,
+                    sig.decl,
+                    body,
+                    item.span,
+                    item.hir_id(),
+                    item.span.with_hi(sig.decl.output.span().hi()),
+                    "this method could have a `#[must_use]` attribute",
+                );
+            }
+        }
+    }
+}
+
+fn check_needless_must_use(
+    cx: &LateContext<'_>,
+    decl: &hir::FnDecl<'_>,
+    item_id: hir::HirId,
+    item_span: Span,
+    fn_header_span: Span,
+    attr: &Attribute,
+) {
+    if in_external_macro(cx.sess(), item_span) {
+        return;
+    }
+    if returns_unit(decl) {
+        span_lint_and_then(
+            cx,
+            MUST_USE_UNIT,
+            fn_header_span,
+            "this unit-returning function has a `#[must_use]` attribute",
+            |diag| {
+                diag.span_suggestion(
+                    attr.span,
+                    "remove the attribute",
+                    "".into(),
+                    Applicability::MachineApplicable,
+                );
+            },
+        );
+    } else if attr.value_str().is_none() && is_must_use_ty(cx, return_ty(cx, item_id)) {
+        span_lint_and_help(
+            cx,
+            DOUBLE_MUST_USE,
+            fn_header_span,
+            "this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`",
+            None,
+            "either add some descriptive text or remove the attribute",
+        );
+    }
+}
+
+fn check_must_use_candidate<'tcx>(
+    cx: &LateContext<'tcx>,
+    decl: &'tcx hir::FnDecl<'_>,
+    body: &'tcx hir::Body<'_>,
+    item_span: Span,
+    item_id: hir::HirId,
+    fn_span: Span,
+    msg: &str,
+) {
+    if has_mutable_arg(cx, body)
+        || mutates_static(cx, body)
+        || in_external_macro(cx.sess(), item_span)
+        || returns_unit(decl)
+        || !cx.access_levels.is_exported(item_id)
+        || is_must_use_ty(cx, return_ty(cx, item_id))
+    {
+        return;
+    }
+    span_lint_and_then(cx, MUST_USE_CANDIDATE, fn_span, msg, |diag| {
+        if let Some(snippet) = snippet_opt(cx, fn_span) {
+            diag.span_suggestion(
+                fn_span,
+                "add the attribute",
+                format!("#[must_use] {}", snippet),
+                Applicability::MachineApplicable,
+            );
+        }
+    });
+}
+
+fn returns_unit(decl: &hir::FnDecl<'_>) -> bool {
+    match decl.output {
+        hir::FnRetTy::DefaultReturn(_) => true,
+        hir::FnRetTy::Return(ty) => match ty.kind {
+            hir::TyKind::Tup(tys) => tys.is_empty(),
+            hir::TyKind::Never => true,
+            _ => false,
+        },
+    }
+}
+
+fn has_mutable_arg(cx: &LateContext<'_>, body: &hir::Body<'_>) -> bool {
+    let mut tys = DefIdSet::default();
+    body.params.iter().any(|param| is_mutable_pat(cx, param.pat, &mut tys))
+}
+
+fn is_mutable_pat(cx: &LateContext<'_>, pat: &hir::Pat<'_>, tys: &mut DefIdSet) -> bool {
+    if let hir::PatKind::Wild = pat.kind {
+        return false; // ignore `_` patterns
+    }
+    if cx.tcx.has_typeck_results(pat.hir_id.owner.to_def_id()) {
+        is_mutable_ty(cx, cx.tcx.typeck(pat.hir_id.owner).pat_ty(pat), pat.span, tys)
+    } else {
+        false
+    }
+}
+
+static KNOWN_WRAPPER_TYS: &[&[&str]] = &[&["alloc", "rc", "Rc"], &["std", "sync", "Arc"]];
+
+fn is_mutable_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span, tys: &mut DefIdSet) -> bool {
+    match *ty.kind() {
+        // primitive types are never mutable
+        ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => false,
+        ty::Adt(adt, substs) => {
+            tys.insert(adt.did) && !ty.is_freeze(cx.tcx.at(span), cx.param_env)
+                || KNOWN_WRAPPER_TYS.iter().any(|path| match_def_path(cx, adt.did, path))
+                    && substs.types().any(|ty| is_mutable_ty(cx, ty, span, tys))
+        },
+        ty::Tuple(substs) => substs.types().any(|ty| is_mutable_ty(cx, ty, span, tys)),
+        ty::Array(ty, _) | ty::Slice(ty) => is_mutable_ty(cx, ty, span, tys),
+        ty::RawPtr(ty::TypeAndMut { ty, mutbl }) | ty::Ref(_, ty, mutbl) => {
+            mutbl == hir::Mutability::Mut || is_mutable_ty(cx, ty, span, tys)
+        },
+        // calling something constitutes a side effect, so return true on all callables
+        // also never calls need not be used, so return true for them, too
+        _ => true,
+    }
+}
+
+struct StaticMutVisitor<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    mutates_static: bool,
+}
+
+impl<'a, 'tcx> intravisit::Visitor<'tcx> for StaticMutVisitor<'a, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
+        use hir::ExprKind::{AddrOf, Assign, AssignOp, Call, MethodCall};
+
+        if self.mutates_static {
+            return;
+        }
+        match expr.kind {
+            Call(_, args) | MethodCall(_, _, args, _) => {
+                let mut tys = DefIdSet::default();
+                for arg in args {
+                    if self.cx.tcx.has_typeck_results(arg.hir_id.owner.to_def_id())
+                        && is_mutable_ty(
+                            self.cx,
+                            self.cx.tcx.typeck(arg.hir_id.owner).expr_ty(arg),
+                            arg.span,
+                            &mut tys,
+                        )
+                        && is_mutated_static(arg)
+                    {
+                        self.mutates_static = true;
+                        return;
+                    }
+                    tys.clear();
+                }
+            },
+            Assign(target, ..) | AssignOp(_, target, _) | AddrOf(_, hir::Mutability::Mut, target) => {
+                self.mutates_static |= is_mutated_static(target)
+            },
+            _ => {},
+        }
+    }
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::None
+    }
+}
+
+fn is_mutated_static(e: &hir::Expr<'_>) -> bool {
+    use hir::ExprKind::{Field, Index, Path};
+
+    match e.kind {
+        Path(QPath::Resolved(_, path)) => !matches!(path.res, Res::Local(_)),
+        Path(_) => true,
+        Field(inner, _) | Index(inner, _) => is_mutated_static(inner),
+        _ => false,
+    }
+}
+
+fn mutates_static<'tcx>(cx: &LateContext<'tcx>, body: &'tcx hir::Body<'_>) -> bool {
+    let mut v = StaticMutVisitor {
+        cx,
+        mutates_static: false,
+    };
+    intravisit::walk_expr(&mut v, &body.value);
+    v.mutates_static
+}

src/tools/clippy/clippy_lints/src/functions/not_unsafe_ptr_arg_deref.rs

@@ -0,0 +1,124 @@
+use rustc_hir::{self as hir, intravisit, HirIdSet};
+use rustc_lint::LateContext;
+use rustc_middle::{hir::map::Map, ty};
+
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::ty::type_is_unsafe_function;
+use clippy_utils::{iter_input_pats, path_to_local};
+
+use super::NOT_UNSAFE_PTR_ARG_DEREF;
+
+pub(super) fn check_fn(
+    cx: &LateContext<'tcx>,
+    kind: intravisit::FnKind<'tcx>,
+    decl: &'tcx hir::FnDecl<'tcx>,
+    body: &'tcx hir::Body<'tcx>,
+    hir_id: hir::HirId,
+) {
+    let unsafety = match kind {
+        intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _) => unsafety,
+        intravisit::FnKind::Method(_, sig, _) => sig.header.unsafety,
+        intravisit::FnKind::Closure => return,
+    };
+
+    check_raw_ptr(cx, unsafety, decl, body, hir_id);
+}
+
+pub(super) fn check_trait_item(cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
+    if let hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(eid)) = item.kind {
+        let body = cx.tcx.hir().body(eid);
+        check_raw_ptr(cx, sig.header.unsafety, sig.decl, body, item.hir_id());
+    }
+}
+
+fn check_raw_ptr(
+    cx: &LateContext<'tcx>,
+    unsafety: hir::Unsafety,
+    decl: &'tcx hir::FnDecl<'tcx>,
+    body: &'tcx hir::Body<'tcx>,
+    hir_id: hir::HirId,
+) {
+    let expr = &body.value;
+    if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(hir_id) {
+        let raw_ptrs = iter_input_pats(decl, body)
+            .zip(decl.inputs.iter())
+            .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
+            .collect::<HirIdSet>();
+
+        if !raw_ptrs.is_empty() {
+            let typeck_results = cx.tcx.typeck_body(body.id());
+            let mut v = DerefVisitor {
+                cx,
+                ptrs: raw_ptrs,
+                typeck_results,
+            };
+
+            intravisit::walk_expr(&mut v, expr);
+        }
+    }
+}
+
+fn raw_ptr_arg(arg: &hir::Param<'_>, ty: &hir::Ty<'_>) -> Option<hir::HirId> {
+    if let (&hir::PatKind::Binding(_, id, _, _), &hir::TyKind::Ptr(_)) = (&arg.pat.kind, &ty.kind) {
+        Some(id)
+    } else {
+        None
+    }
+}
+
+struct DerefVisitor<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    ptrs: HirIdSet,
+    typeck_results: &'a ty::TypeckResults<'tcx>,
+}
+
+impl<'a, 'tcx> intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
+        match expr.kind {
+            hir::ExprKind::Call(f, args) => {
+                let ty = self.typeck_results.expr_ty(f);
+
+                if type_is_unsafe_function(self.cx, ty) {
+                    for arg in args {
+                        self.check_arg(arg);
+                    }
+                }
+            },
+            hir::ExprKind::MethodCall(_, _, args, _) => {
+                let def_id = self.typeck_results.type_dependent_def_id(expr.hir_id).unwrap();
+                let base_type = self.cx.tcx.type_of(def_id);
+
+                if type_is_unsafe_function(self.cx, base_type) {
+                    for arg in args {
+                        self.check_arg(arg);
+                    }
+                }
+            },
+            hir::ExprKind::Unary(hir::UnOp::Deref, ptr) => self.check_arg(ptr),
+            _ => (),
+        }
+
+        intravisit::walk_expr(self, expr);
+    }
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::None
+    }
+}
+
+impl<'a, 'tcx> DerefVisitor<'a, 'tcx> {
+    fn check_arg(&self, ptr: &hir::Expr<'_>) {
+        if let Some(id) = path_to_local(ptr) {
+            if self.ptrs.contains(&id) {
+                span_lint(
+                    self.cx,
+                    NOT_UNSAFE_PTR_ARG_DEREF,
+                    ptr.span,
+                    "this public function dereferences a raw pointer but is not marked `unsafe`",
+                );
+            }
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/functions/result_unit_err.rs

@@ -0,0 +1,66 @@
+use rustc_hir as hir;
+use rustc_lint::{LateContext, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty;
+use rustc_span::{sym, Span};
+use rustc_typeck::hir_ty_to_ty;
+
+use if_chain::if_chain;
+
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::trait_ref_of_method;
+use clippy_utils::ty::is_type_diagnostic_item;
+
+use super::RESULT_UNIT_ERR;
+
+pub(super) fn check_item(cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
+    if let hir::ItemKind::Fn(ref sig, ref _generics, _) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+        if is_public {
+            check_result_unit_err(cx, sig.decl, item.span, fn_header_span);
+        }
+    }
+}
+
+pub(super) fn check_impl_item(cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
+    if let hir::ImplItemKind::Fn(ref sig, _) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+        if is_public && trait_ref_of_method(cx, item.hir_id()).is_none() {
+            check_result_unit_err(cx, sig.decl, item.span, fn_header_span);
+        }
+    }
+}
+
+pub(super) fn check_trait_item(cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
+    if let hir::TraitItemKind::Fn(ref sig, _) = item.kind {
+        let is_public = cx.access_levels.is_exported(item.hir_id());
+        let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+        if is_public {
+            check_result_unit_err(cx, sig.decl, item.span, fn_header_span);
+        }
+    }
+}
+
+fn check_result_unit_err(cx: &LateContext<'_>, decl: &hir::FnDecl<'_>, item_span: Span, fn_header_span: Span) {
+    if_chain! {
+        if !in_external_macro(cx.sess(), item_span);
+        if let hir::FnRetTy::Return(ty) = decl.output;
+        let ty = hir_ty_to_ty(cx.tcx, ty);
+        if is_type_diagnostic_item(cx, ty, sym::result_type);
+        if let ty::Adt(_, substs) = ty.kind();
+        let err_ty = substs.type_at(1);
+        if err_ty.is_unit();
+        then {
+            span_lint_and_help(
+                cx,
+                RESULT_UNIT_ERR,
+                fn_header_span,
+                "this returns a `Result<_, ()>`",
+                None,
+                "use a custom `Error` type instead",
+            );
+        }
+    }
+}

src/tools/clippy/clippy_lints/src/functions/too_many_arguments.rs

@@ -0,0 +1,73 @@
+use rustc_hir::{self as hir, intravisit};
+use rustc_lint::LateContext;
+use rustc_span::Span;
+use rustc_target::spec::abi::Abi;
+
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::is_trait_impl_item;
+
+use super::TOO_MANY_ARGUMENTS;
+
+pub(super) fn check_fn(
+    cx: &LateContext<'tcx>,
+    kind: intravisit::FnKind<'tcx>,
+    decl: &'tcx hir::FnDecl<'_>,
+    span: Span,
+    hir_id: hir::HirId,
+    too_many_arguments_threshold: u64,
+) {
+    // don't warn for implementations, it's not their fault
+    if !is_trait_impl_item(cx, hir_id) {
+        // don't lint extern functions decls, it's not their fault either
+        match kind {
+            intravisit::FnKind::Method(
+                _,
+                &hir::FnSig {
+                    header: hir::FnHeader { abi: Abi::Rust, .. },
+                    ..
+                },
+                _,
+            )
+            | intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _) => check_arg_number(
+                cx,
+                decl,
+                span.with_hi(decl.output.span().hi()),
+                too_many_arguments_threshold,
+            ),
+            _ => {},
+        }
+    }
+}
+
+pub(super) fn check_trait_item(
+    cx: &LateContext<'tcx>,
+    item: &'tcx hir::TraitItem<'_>,
+    too_many_arguments_threshold: u64,
+) {
+    if let hir::TraitItemKind::Fn(ref sig, _) = item.kind {
+        // don't lint extern functions decls, it's not their fault
+        if sig.header.abi == Abi::Rust {
+            check_arg_number(
+                cx,
+                sig.decl,
+                item.span.with_hi(sig.decl.output.span().hi()),
+                too_many_arguments_threshold,
+            );
+        }
+    }
+}
+
+fn check_arg_number(cx: &LateContext<'_>, decl: &hir::FnDecl<'_>, fn_span: Span, too_many_arguments_threshold: u64) {
+    let args = decl.inputs.len() as u64;
+    if args > too_many_arguments_threshold {
+        span_lint(
+            cx,
+            TOO_MANY_ARGUMENTS,
+            fn_span,
+            &format!(
+                "this function has too many arguments ({}/{})",
+                args, too_many_arguments_threshold
+            ),
+        );
+    }
+}

src/tools/clippy/clippy_lints/src/functions/too_many_lines.rs

@@ -0,0 +1,68 @@
+use rustc_hir as hir;
+use rustc_lint::{LateContext, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_span::Span;
+
+use clippy_utils::diagnostics::span_lint;
+use clippy_utils::source::snippet;
+
+use super::TOO_MANY_LINES;
+
+pub(super) fn check_fn(cx: &LateContext<'_>, span: Span, body: &'tcx hir::Body<'_>, too_many_lines_threshold: u64) {
+    if in_external_macro(cx.sess(), span) {
+        return;
+    }
+
+    let code_snippet = snippet(cx, body.value.span, "..");
+    let mut line_count: u64 = 0;
+    let mut in_comment = false;
+    let mut code_in_line;
+
+    // Skip the surrounding function decl.
+    let start_brace_idx = code_snippet.find('{').map_or(0, |i| i + 1);
+    let end_brace_idx = code_snippet.rfind('}').unwrap_or_else(|| code_snippet.len());
+    let function_lines = code_snippet[start_brace_idx..end_brace_idx].lines();
+
+    for mut line in function_lines {
+        code_in_line = false;
+        loop {
+            line = line.trim_start();
+            if line.is_empty() {
+                break;
+            }
+            if in_comment {
+                if let Some(i) = line.find("*/") {
+                    line = &line[i + 2..];
+                    in_comment = false;
+                    continue;
+                }
+            } else {
+                let multi_idx = line.find("/*").unwrap_or_else(|| line.len());
+                let single_idx = line.find("//").unwrap_or_else(|| line.len());
+                code_in_line |= multi_idx > 0 && single_idx > 0;
+                // Implies multi_idx is below line.len()
+                if multi_idx < single_idx {
+                    line = &line[multi_idx + 2..];
+                    in_comment = true;
+                    continue;
+                }
+            }
+            break;
+        }
+        if code_in_line {
+            line_count += 1;
+        }
+    }
+
+    if line_count > too_many_lines_threshold {
+        span_lint(
+            cx,
+            TOO_MANY_LINES,
+            span,
+            &format!(
+                "this function has too many lines ({}/{})",
+                line_count, too_many_lines_threshold
+            ),
+        )
+    }
+}

src/tools/clippy/clippy_lints/src/get_last_with_len.rs

@@ -51,7 +51,7 @@ impl<'tcx> LateLintPass<'tcx> for GetLastWithLen {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
             // Is a method call
-            if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
+            if let ExprKind::MethodCall(path, _, args, _) = expr.kind;
 
             // Method name is "get"
             if path.ident.name == sym!(get);

src/tools/clippy/clippy_lints/src/identity_op.rs

@@ -35,7 +35,7 @@ impl<'tcx> LateLintPass<'tcx> for IdentityOp {
         if e.span.from_expansion() {
             return;
         }
-        if let ExprKind::Binary(cmp, ref left, ref right) = e.kind {
+        if let ExprKind::Binary(cmp, left, right) = e.kind {
             if is_allowed(cx, cmp, left, right) {
                 return;
             }

src/tools/clippy/clippy_lints/src/if_let_mutex.rs

@@ -55,8 +55,8 @@ impl<'tcx> LateLintPass<'tcx> for IfLetMutex {
             cx,
         };
         if let ExprKind::Match(
-            ref op,
-            ref arms,
+            op,
+            arms,
             MatchSource::IfLetDesugar {
                 contains_else_clause: true,
             },
@@ -64,7 +64,7 @@ impl<'tcx> LateLintPass<'tcx> for IfLetMutex {
         {
             op_visit.visit_expr(op);
             if op_visit.mutex_lock_called {
-                for arm in *arms {
+                for arm in arms {
                     arm_visit.visit_arm(arm);
                 }
 
@@ -94,14 +94,11 @@ impl<'tcx> Visitor<'tcx> for OppVisitor<'_, 'tcx> {
     type Map = Map<'tcx>;
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
-        if_chain! {
-            if let Some(mutex) = is_mutex_lock_call(self.cx, expr);
-            then {
+        if let Some(mutex) = is_mutex_lock_call(self.cx, expr) {
             self.found_mutex = Some(mutex);
             self.mutex_lock_called = true;
             return;
         }
-        }
         visit::walk_expr(self, expr);
     }
 
@@ -121,14 +118,11 @@ impl<'tcx> Visitor<'tcx> for ArmVisitor<'_, 'tcx> {
     type Map = Map<'tcx>;
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
-        if_chain! {
-            if let Some(mutex) = is_mutex_lock_call(self.cx, expr);
-            then {
+        if let Some(mutex) = is_mutex_lock_call(self.cx, expr) {
             self.found_mutex = Some(mutex);
             self.mutex_lock_called = true;
             return;
         }
-        }
         visit::walk_expr(self, expr);
     }
 

src/tools/clippy/clippy_lints/src/if_let_some_result.rs

@@ -44,9 +44,9 @@ declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]);
 impl<'tcx> LateLintPass<'tcx> for OkIfLet {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! { //begin checking variables
-            if let ExprKind::Match(ref op, ref body, MatchSource::IfLetDesugar { .. }) = expr.kind; //test if expr is if let
-            if let ExprKind::MethodCall(_, ok_span, ref result_types, _) = op.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
-            if let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _)  = body[0].pat.kind; //get operation
+            if let ExprKind::Match(op, body, MatchSource::IfLetDesugar { .. }) = expr.kind; //test if expr is if let
+            if let ExprKind::MethodCall(_, ok_span, result_types, _) = op.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
+            if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _)  = body[0].pat.kind; //get operation
             if method_chain_args(op, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
             if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&result_types[0]), sym::result_type);
             if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";

src/tools/clippy/clippy_lints/src/if_then_some_else_none.rs

@@ -72,15 +72,15 @@ impl LateLintPass<'_> for IfThenSomeElseNone {
         }
 
         if_chain! {
-            if let ExprKind::If(ref cond, ref then, Some(ref els)) = expr.kind;
-            if let ExprKind::Block(ref then_block, _) = then.kind;
-            if let Some(ref then_expr) = then_block.expr;
-            if let ExprKind::Call(ref then_call, [then_arg]) = then_expr.kind;
+            if let ExprKind::If(cond, then, Some(els)) = expr.kind;
+            if let ExprKind::Block(then_block, _) = then.kind;
+            if let Some(then_expr) = then_block.expr;
+            if let ExprKind::Call(then_call, [then_arg]) = then_expr.kind;
             if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
             if match_qpath(then_call_qpath, &clippy_utils::paths::OPTION_SOME);
-            if let ExprKind::Block(ref els_block, _) = els.kind;
+            if let ExprKind::Block(els_block, _) = els.kind;
             if els_block.stmts.is_empty();
-            if let Some(ref els_expr) = els_block.expr;
+            if let Some(els_expr) = els_block.expr;
             if let ExprKind::Path(ref els_call_qpath) = els_expr.kind;
             if match_qpath(els_call_qpath, &clippy_utils::paths::OPTION_NONE);
             then {

src/tools/clippy/clippy_lints/src/implicit_hasher.rs

@@ -0,0 +1,377 @@
+#![allow(rustc::default_hash_types)]
+
+use std::borrow::Cow;
+use std::collections::BTreeMap;
+
+use rustc_errors::DiagnosticBuilder;
+use rustc_hir as hir;
+use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, NestedVisitorMap, Visitor};
+use rustc_hir::{Body, Expr, ExprKind, GenericArg, Item, ItemKind, QPath, TyKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::hir::map::Map;
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::{Ty, TyS, TypeckResults};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+use rustc_span::symbol::sym;
+use rustc_typeck::hir_ty_to_ty;
+
+use if_chain::if_chain;
+
+use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
+use clippy_utils::paths;
+use clippy_utils::source::{snippet, snippet_opt};
+use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::{differing_macro_contexts, match_path};
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for public `impl` or `fn` missing generalization
+    /// over different hashers and implicitly defaulting to the default hashing
+    /// algorithm (`SipHash`).
+    ///
+    /// **Why is this bad?** `HashMap` or `HashSet` with custom hashers cannot be
+    /// used with them.
+    ///
+    /// **Known problems:** Suggestions for replacing constructors can contain
+    /// false-positives. Also applying suggestions can require modification of other
+    /// pieces of code, possibly including external crates.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # use std::collections::HashMap;
+    /// # use std::hash::{Hash, BuildHasher};
+    /// # trait Serialize {};
+    /// impl<K: Hash + Eq, V> Serialize for HashMap<K, V> { }
+    ///
+    /// pub fn foo(map: &mut HashMap<i32, i32>) { }
+    /// ```
+    /// could be rewritten as
+    /// ```rust
+    /// # use std::collections::HashMap;
+    /// # use std::hash::{Hash, BuildHasher};
+    /// # trait Serialize {};
+    /// impl<K: Hash + Eq, V, S: BuildHasher> Serialize for HashMap<K, V, S> { }
+    ///
+    /// pub fn foo<S: BuildHasher>(map: &mut HashMap<i32, i32, S>) { }
+    /// ```
+    pub IMPLICIT_HASHER,
+    pedantic,
+    "missing generalization over different hashers"
+}
+
+declare_lint_pass!(ImplicitHasher => [IMPLICIT_HASHER]);
+
+impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
+    #[allow(clippy::cast_possible_truncation, clippy::too_many_lines)]
+    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
+        use rustc_span::BytePos;
+
+        fn suggestion<'tcx>(
+            cx: &LateContext<'tcx>,
+            diag: &mut DiagnosticBuilder<'_>,
+            generics_span: Span,
+            generics_suggestion_span: Span,
+            target: &ImplicitHasherType<'_>,
+            vis: ImplicitHasherConstructorVisitor<'_, '_, '_>,
+        ) {
+            let generics_snip = snippet(cx, generics_span, "");
+            // trim `<` `>`
+            let generics_snip = if generics_snip.is_empty() {
+                ""
+            } else {
+                &generics_snip[1..generics_snip.len() - 1]
+            };
+
+            multispan_sugg(
+                diag,
+                "consider adding a type parameter",
+                vec![
+                    (
+                        generics_suggestion_span,
+                        format!(
+                            "<{}{}S: ::std::hash::BuildHasher{}>",
+                            generics_snip,
+                            if generics_snip.is_empty() { "" } else { ", " },
+                            if vis.suggestions.is_empty() {
+                                ""
+                            } else {
+                                // request users to add `Default` bound so that generic constructors can be used
+                                " + Default"
+                            },
+                        ),
+                    ),
+                    (
+                        target.span(),
+                        format!("{}<{}, S>", target.type_name(), target.type_arguments(),),
+                    ),
+                ],
+            );
+
+            if !vis.suggestions.is_empty() {
+                multispan_sugg(diag, "...and use generic constructor", vis.suggestions);
+            }
+        }
+
+        if !cx.access_levels.is_exported(item.hir_id()) {
+            return;
+        }
+
+        match item.kind {
+            ItemKind::Impl(ref impl_) => {
+                let mut vis = ImplicitHasherTypeVisitor::new(cx);
+                vis.visit_ty(impl_.self_ty);
+
+                for target in &vis.found {
+                    if differing_macro_contexts(item.span, target.span()) {
+                        return;
+                    }
+
+                    let generics_suggestion_span = impl_.generics.span.substitute_dummy({
+                        let pos = snippet_opt(cx, item.span.until(target.span()))
+                            .and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4)));
+                        if let Some(pos) = pos {
+                            Span::new(pos, pos, item.span.data().ctxt)
+                        } else {
+                            return;
+                        }
+                    });
+
+                    let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
+                    for item in impl_.items.iter().map(|item| cx.tcx.hir().impl_item(item.id)) {
+                        ctr_vis.visit_impl_item(item);
+                    }
+
+                    span_lint_and_then(
+                        cx,
+                        IMPLICIT_HASHER,
+                        target.span(),
+                        &format!(
+                            "impl for `{}` should be generalized over different hashers",
+                            target.type_name()
+                        ),
+                        move |diag| {
+                            suggestion(cx, diag, impl_.generics.span, generics_suggestion_span, target, ctr_vis);
+                        },
+                    );
+                }
+            },
+            ItemKind::Fn(ref sig, ref generics, body_id) => {
+                let body = cx.tcx.hir().body(body_id);
+
+                for ty in sig.decl.inputs {
+                    let mut vis = ImplicitHasherTypeVisitor::new(cx);
+                    vis.visit_ty(ty);
+
+                    for target in &vis.found {
+                        if in_external_macro(cx.sess(), generics.span) {
+                            continue;
+                        }
+                        let generics_suggestion_span = generics.span.substitute_dummy({
+                            let pos = snippet_opt(cx, item.span.until(body.params[0].pat.span))
+                                .and_then(|snip| {
+                                    let i = snip.find("fn")?;
+                                    Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
+                                })
+                                .expect("failed to create span for type parameters");
+                            Span::new(pos, pos, item.span.data().ctxt)
+                        });
+
+                        let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
+                        ctr_vis.visit_body(body);
+
+                        span_lint_and_then(
+                            cx,
+                            IMPLICIT_HASHER,
+                            target.span(),
+                            &format!(
+                                "parameter of type `{}` should be generalized over different hashers",
+                                target.type_name()
+                            ),
+                            move |diag| {
+                                suggestion(cx, diag, generics.span, generics_suggestion_span, target, ctr_vis);
+                            },
+                        );
+                    }
+                }
+            },
+            _ => {},
+        }
+    }
+}
+
+enum ImplicitHasherType<'tcx> {
+    HashMap(Span, Ty<'tcx>, Cow<'static, str>, Cow<'static, str>),
+    HashSet(Span, Ty<'tcx>, Cow<'static, str>),
+}
+
+impl<'tcx> ImplicitHasherType<'tcx> {
+    /// Checks that `ty` is a target type without a `BuildHasher`.
+    fn new(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'_>) -> Option<Self> {
+        if let TyKind::Path(QPath::Resolved(None, path)) = hir_ty.kind {
+            let params: Vec<_> = path
+                .segments
+                .last()
+                .as_ref()?
+                .args
+                .as_ref()?
+                .args
+                .iter()
+                .filter_map(|arg| match arg {
+                    GenericArg::Type(ty) => Some(ty),
+                    _ => None,
+                })
+                .collect();
+            let params_len = params.len();
+
+            let ty = hir_ty_to_ty(cx.tcx, hir_ty);
+
+            if is_type_diagnostic_item(cx, ty, sym::hashmap_type) && params_len == 2 {
+                Some(ImplicitHasherType::HashMap(
+                    hir_ty.span,
+                    ty,
+                    snippet(cx, params[0].span, "K"),
+                    snippet(cx, params[1].span, "V"),
+                ))
+            } else if is_type_diagnostic_item(cx, ty, sym::hashset_type) && params_len == 1 {
+                Some(ImplicitHasherType::HashSet(
+                    hir_ty.span,
+                    ty,
+                    snippet(cx, params[0].span, "T"),
+                ))
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
+
+    fn type_name(&self) -> &'static str {
+        match *self {
+            ImplicitHasherType::HashMap(..) => "HashMap",
+            ImplicitHasherType::HashSet(..) => "HashSet",
+        }
+    }
+
+    fn type_arguments(&self) -> String {
+        match *self {
+            ImplicitHasherType::HashMap(.., ref k, ref v) => format!("{}, {}", k, v),
+            ImplicitHasherType::HashSet(.., ref t) => format!("{}", t),
+        }
+    }
+
+    fn ty(&self) -> Ty<'tcx> {
+        match *self {
+            ImplicitHasherType::HashMap(_, ty, ..) | ImplicitHasherType::HashSet(_, ty, ..) => ty,
+        }
+    }
+
+    fn span(&self) -> Span {
+        match *self {
+            ImplicitHasherType::HashMap(span, ..) | ImplicitHasherType::HashSet(span, ..) => span,
+        }
+    }
+}
+
+struct ImplicitHasherTypeVisitor<'a, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    found: Vec<ImplicitHasherType<'tcx>>,
+}
+
+impl<'a, 'tcx> ImplicitHasherTypeVisitor<'a, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>) -> Self {
+        Self { cx, found: vec![] }
+    }
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for ImplicitHasherTypeVisitor<'a, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn visit_ty(&mut self, t: &'tcx hir::Ty<'_>) {
+        if let Some(target) = ImplicitHasherType::new(self.cx, t) {
+            self.found.push(target);
+        }
+
+        walk_ty(self, t);
+    }
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::None
+    }
+}
+
+/// Looks for default-hasher-dependent constructors like `HashMap::new`.
+struct ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
+    cx: &'a LateContext<'tcx>,
+    maybe_typeck_results: Option<&'tcx TypeckResults<'tcx>>,
+    target: &'b ImplicitHasherType<'tcx>,
+    suggestions: BTreeMap<Span, String>,
+}
+
+impl<'a, 'b, 'tcx> ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>, target: &'b ImplicitHasherType<'tcx>) -> Self {
+        Self {
+            cx,
+            maybe_typeck_results: cx.maybe_typeck_results(),
+            target,
+            suggestions: BTreeMap::new(),
+        }
+    }
+}
+
+impl<'a, 'b, 'tcx> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
+    type Map = Map<'tcx>;
+
+    fn visit_body(&mut self, body: &'tcx Body<'_>) {
+        let old_maybe_typeck_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body.id()));
+        walk_body(self, body);
+        self.maybe_typeck_results = old_maybe_typeck_results;
+    }
+
+    fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
+        if_chain! {
+            if let ExprKind::Call(fun, args) = e.kind;
+            if let ExprKind::Path(QPath::TypeRelative(ty, method)) = fun.kind;
+            if let TyKind::Path(QPath::Resolved(None, ty_path)) = ty.kind;
+            then {
+                if !TyS::same_type(self.target.ty(), self.maybe_typeck_results.unwrap().expr_ty(e)) {
+                    return;
+                }
+
+                if match_path(ty_path, &paths::HASHMAP) {
+                    if method.ident.name == sym::new {
+                        self.suggestions
+                            .insert(e.span, "HashMap::default()".to_string());
+                    } else if method.ident.name == sym!(with_capacity) {
+                        self.suggestions.insert(
+                            e.span,
+                            format!(
+                                "HashMap::with_capacity_and_hasher({}, Default::default())",
+                                snippet(self.cx, args[0].span, "capacity"),
+                            ),
+                        );
+                    }
+                } else if match_path(ty_path, &paths::HASHSET) {
+                    if method.ident.name == sym::new {
+                        self.suggestions
+                            .insert(e.span, "HashSet::default()".to_string());
+                    } else if method.ident.name == sym!(with_capacity) {
+                        self.suggestions.insert(
+                            e.span,
+                            format!(
+                                "HashSet::with_capacity_and_hasher({}, Default::default())",
+                                snippet(self.cx, args[0].span, "capacity"),
+                            ),
+                        );
+                    }
+                }
+            }
+        }
+
+        walk_expr(self, e);
+    }
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
+    }
+}

src/tools/clippy/clippy_lints/src/implicit_return.rs

@@ -100,10 +100,10 @@ fn expr_match(cx: &LateContext<'_>, expr: &Expr<'_>) {
 
             if check_all_arms {
                 for arm in arms {
-                    expr_match(cx, &arm.body);
+                    expr_match(cx, arm.body);
                 }
             } else {
-                expr_match(cx, &arms.first().expect("`if let` doesn't have a single arm").body);
+                expr_match(cx, arms.first().expect("`if let` doesn't have a single arm").body);
             }
         },
         // skip if it already has a return statement

src/tools/clippy/clippy_lints/src/implicit_saturating_sub.rs

@@ -46,21 +46,21 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
             if let ExprKind::If(cond, then, None) = &expr.kind;
 
             // Check if the conditional expression is a binary operation
-            if let ExprKind::Binary(ref cond_op, ref cond_left, ref cond_right) = cond.kind;
+            if let ExprKind::Binary(ref cond_op, cond_left, cond_right) = cond.kind;
 
             // Ensure that the binary operator is >, != and <
             if BinOpKind::Ne == cond_op.node || BinOpKind::Gt == cond_op.node || BinOpKind::Lt == cond_op.node;
 
             // Check if the true condition block has only one statement
-            if let ExprKind::Block(ref block, _) = then.kind;
+            if let ExprKind::Block(block, _) = then.kind;
             if block.stmts.len() == 1 && block.expr.is_none();
 
             // Check if assign operation is done
-            if let StmtKind::Semi(ref e) = block.stmts[0].kind;
+            if let StmtKind::Semi(e) = block.stmts[0].kind;
             if let Some(target) = subtracts_one(cx, e);
 
             // Extracting out the variable name
-            if let ExprKind::Path(QPath::Resolved(_, ref ares_path)) = target.kind;
+            if let ExprKind::Path(QPath::Resolved(_, ares_path)) = target.kind;
 
             then {
                 // Handle symmetric conditions in the if statement
@@ -104,7 +104,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
                             print_lint_and_sugg(cx, &var_name, expr);
                         };
                     },
-                    ExprKind::Call(ref func, _) => {
+                    ExprKind::Call(func, _) => {
                         if let ExprKind::Path(ref cond_num_path) = func.kind {
                             if INT_TYPES.iter().any(|int_type| match_qpath(cond_num_path, &[int_type, "min_value"])) {
                                 print_lint_and_sugg(cx, &var_name, expr);
@@ -120,7 +120,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
 
 fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &Expr<'a>) -> Option<&'a Expr<'a>> {
     match expr.kind {
-        ExprKind::AssignOp(ref op1, ref target, ref value) => {
+        ExprKind::AssignOp(ref op1, target, value) => {
             if_chain! {
                 if BinOpKind::Sub == op1.node;
                 // Check if literal being subtracted is one
@@ -133,9 +133,9 @@ fn subtracts_one<'a>(cx: &LateContext<'_>, expr: &Expr<'a>) -> Option<&'a Expr<'
                 }
             }
         },
-        ExprKind::Assign(ref target, ref value, _) => {
+        ExprKind::Assign(target, value, _) => {
             if_chain! {
-                if let ExprKind::Binary(ref op1, ref left1, ref right1) = value.kind;
+                if let ExprKind::Binary(ref op1, left1, right1) = value.kind;
                 if BinOpKind::Sub == op1.node;
 
                 if SpanlessEq::new(cx).eq_expr(left1, target);

src/tools/clippy/clippy_lints/src/indexing_slicing.rs

@@ -88,7 +88,7 @@ declare_lint_pass!(IndexingSlicing => [INDEXING_SLICING, OUT_OF_BOUNDS_INDEXING]
 
 impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let ExprKind::Index(ref array, ref index) = &expr.kind {
+        if let ExprKind::Index(array, index) = &expr.kind {
             let ty = cx.typeck_results().expr_ty(array).peel_refs();
             if let Some(range) = higher::range(index) {
                 // Ranged indexes, i.e., &x[n..m], &x[n..], &x[..n] and &x[..]