Merge commit 'bf1c6f9871f430e284b17aa44059e0d0395e28a6' into clippyup

74 files changed, 2120 insertions, 566 deletions

diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index 137a7363094..6c92e10522c 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -12,12 +12,12 @@ your PR is merged.
 If you added a new lint, here's a checklist for things that will be
 checked during review or continuous integration.
 
-- [ ] Followed [lint naming conventions][lint_naming]
-- [ ] Added passing UI tests (including committed `.stderr` file)
-- [ ] `cargo test` passes locally
-- [ ] Executed `cargo dev update_lints`
-- [ ] Added lint documentation
-- [ ] Run `cargo dev fmt`
+- \[ ] Followed [lint naming conventions][lint_naming]
+- \[ ] Added passing UI tests (including committed `.stderr` file)
+- \[ ] `cargo test` passes locally
+- \[ ] Executed `cargo dev update_lints`
+- \[ ] Added lint documentation
+- \[ ] Run `cargo dev fmt`
 
 [lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
 
diff --git a/.github/workflows/clippy.yml b/.github/workflows/clippy.yml
index 99e371631b1..cf4aa39e49b 100644
--- a/.github/workflows/clippy.yml
+++ b/.github/workflows/clippy.yml
@@ -36,14 +36,14 @@ jobs:
         github_token: "${{ secrets.github_token }}"
 
     - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.3
+      uses: actions-rs/toolchain@v1.0.6
       with:
         toolchain: nightly
         target: x86_64-unknown-linux-gnu
         profile: minimal
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Run cargo update
       run: cargo update
@@ -63,7 +63,7 @@ jobs:
     - name: Set LD_LIBRARY_PATH (Linux)
       run: |
         SYSROOT=$(rustc --print sysroot)
-        echo "::set-env name=LD_LIBRARY_PATH::${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}"
+        echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
 
     - name: Build
       run: cargo build --features deny-warnings
diff --git a/.github/workflows/clippy_bors.yml b/.github/workflows/clippy_bors.yml
index fd0cd7a1890..7509d90c6c2 100644
--- a/.github/workflows/clippy_bors.yml
+++ b/.github/workflows/clippy_bors.yml
@@ -11,6 +11,10 @@ env:
   CARGO_TARGET_DIR: '${{ github.workspace }}/target'
   NO_FMT_TEST: 1
 
+defaults:
+  run:
+    shell: bash
+
 jobs:
   changelog:
     runs-on: ubuntu-latest
@@ -20,7 +24,7 @@ jobs:
       with:
         github_token: "${{ secrets.github_token }}"
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
       with:
         ref: ${{ github.ref }}
 
@@ -81,14 +85,14 @@ jobs:
       if: matrix.host == 'i686-unknown-linux-gnu'
 
     - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.3
+      uses: actions-rs/toolchain@v1.0.6
       with:
         toolchain: nightly
         target: ${{ matrix.host }}
         profile: minimal
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Run cargo update
       run: cargo update
@@ -105,14 +109,13 @@ jobs:
       run: bash setup-toolchain.sh
       env:
         HOST_TOOLCHAIN: ${{ matrix.host }}
-      shell: bash
 
     # Run
     - name: Set LD_LIBRARY_PATH (Linux)
       if: runner.os == 'Linux'
       run: |
         SYSROOT=$(rustc --print sysroot)
-        echo "::set-env name=LD_LIBRARY_PATH::${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}"
+        echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
     - name: Link rustc dylib (MacOS)
       if: runner.os == 'macOS'
       run: |
@@ -122,41 +125,33 @@ jobs:
     - name: Set PATH (Windows)
       if: runner.os == 'Windows'
       run: |
-        $sysroot = rustc --print sysroot
-        $env:PATH += ';' + $sysroot + '\bin'
-        echo "::set-env name=PATH::$env:PATH"
+        SYSROOT=$(rustc --print sysroot)
+        echo "$SYSROOT/bin" >> $GITHUB_PATH
 
     - name: Build
       run: cargo build --features deny-warnings
-      shell: bash
 
     - name: Test
       run: cargo test --features deny-warnings
-      shell: bash
 
     - name: Test clippy_lints
       run: cargo test --features deny-warnings
-      shell: bash
       working-directory: clippy_lints
 
     - name: Test rustc_tools_util
       run: cargo test --features deny-warnings
-      shell: bash
       working-directory: rustc_tools_util
 
     - name: Test clippy_dev
       run: cargo test --features deny-warnings
-      shell: bash
       working-directory: clippy_dev
 
     - name: Test cargo-clippy
       run: ../target/debug/cargo-clippy
-      shell: bash
       working-directory: clippy_workspace_tests
 
     - name: Test clippy-driver
       run: bash .github/driver.sh
-      shell: bash
       env:
         OS: ${{ runner.os }}
 
@@ -165,7 +160,7 @@ jobs:
       run: |
         cargo +nightly install cargo-cache --no-default-features --features ci-autoclean cargo-cache
         cargo cache
-      shell: bash
+
   integration_build:
     needs: changelog
     runs-on: ubuntu-latest
@@ -177,14 +172,14 @@ jobs:
         github_token: "${{ secrets.github_token }}"
 
     - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.3
+      uses: actions-rs/toolchain@v1.0.6
       with:
         toolchain: nightly
         target: x86_64-unknown-linux-gnu
         profile: minimal
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Run cargo update
       run: cargo update
@@ -258,14 +253,14 @@ jobs:
         github_token: "${{ secrets.github_token }}"
 
     - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.3
+      uses: actions-rs/toolchain@v1.0.6
       with:
         toolchain: nightly
         target: x86_64-unknown-linux-gnu
         profile: minimal
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Run cargo update
       run: cargo update
diff --git a/.github/workflows/clippy_dev.yml b/.github/workflows/clippy_dev.yml
index ec3b43c2f43..5ee157cf23b 100644
--- a/.github/workflows/clippy_dev.yml
+++ b/.github/workflows/clippy_dev.yml
@@ -23,7 +23,7 @@ jobs:
     steps:
     # Setup
     - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.3
+      uses: actions-rs/toolchain@v1.0.6
       with:
         toolchain: nightly
         target: x86_64-unknown-linux-gnu
@@ -31,7 +31,7 @@ jobs:
         components: rustfmt
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     # Run
     - name: Build
diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index f542f9b02c1..15aeaf907dc 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -21,10 +21,10 @@ jobs:
     steps:
     # Setup
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
       with:
         ref: ${{ env.TARGET_BRANCH }}
         path: 'out'
@@ -34,10 +34,10 @@ jobs:
       if: startswith(github.ref, 'refs/tags/')
       run: |
         TAG=$(basename ${{ github.ref }})
-        echo "::set-env name=TAG_NAME::$TAG"
+        echo "TAG_NAME=$TAG" >> $GITHUB_ENV
     - name: Set beta to true
       if: github.ref == 'refs/heads/beta'
-      run: echo "::set-env name=BETA::true"
+      run: echo "BETA=true" >> $GITHUB_ENV
 
     - name: Use scripts and templates from master branch
       run: |
diff --git a/.github/workflows/remark.yml b/.github/workflows/remark.yml
index cc175e8bf24..4f25a86b2e4 100644
--- a/.github/workflows/remark.yml
+++ b/.github/workflows/remark.yml
@@ -16,10 +16,10 @@ jobs:
     steps:
     # Setup
     - name: Checkout
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v2.3.3
 
     - name: Setup Node.js
-      uses: actions/setup-node@v1.1.0
+      uses: actions/setup-node@v1.4.4
 
     - name: Install remark
       run: npm install remark-cli remark-lint remark-lint-maximum-line-length remark-preset-lint-recommended
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0bd13320dc9..d82f970b8bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1796,6 +1796,7 @@ Released 2018-09-13
 [`manual_saturating_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_saturating_arithmetic
 [`manual_strip`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_strip
 [`manual_swap`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_swap
+[`manual_unwrap_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_unwrap_or
 [`many_single_char_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#many_single_char_names
 [`map_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_clone
 [`map_entry`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_entry
@@ -1892,6 +1893,7 @@ Released 2018-09-13
 [`print_with_newline`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_with_newline
 [`println_empty_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#println_empty_string
 [`ptr_arg`]: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_arg
+[`ptr_eq`]: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq
 [`ptr_offset_with_cast`]: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_offset_with_cast
 [`pub_enum_variant_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#pub_enum_variant_names
 [`question_mark`]: https://rust-lang.github.io/rust-clippy/master/index.html#question_mark
@@ -1917,6 +1919,7 @@ Released 2018-09-13
 [`rest_pat_in_fully_bound_structs`]: https://rust-lang.github.io/rust-clippy/master/index.html#rest_pat_in_fully_bound_structs
 [`result_map_or_into_option`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_map_or_into_option
 [`result_map_unit_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_map_unit_fn
+[`result_unit_err`]: https://rust-lang.github.io/rust-clippy/master/index.html#result_unit_err
 [`reversed_empty_ranges`]: https://rust-lang.github.io/rust-clippy/master/index.html#reversed_empty_ranges
 [`same_functions_in_if_condition`]: https://rust-lang.github.io/rust-clippy/master/index.html#same_functions_in_if_condition
 [`same_item_push`]: https://rust-lang.github.io/rust-clippy/master/index.html#same_item_push
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 100c9edb367..6494695606c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -316,8 +316,8 @@ If you have @bors permissions, you can find an overview of the available
 commands [here][homu_instructions].
 
 [triage]: https://forge.rust-lang.org/release/triage-procedure.html
-[l-crash]: https://github.com/rust-lang/rust-clippy/labels/L-crash%20%3Aboom%3A
-[l-bug]: https://github.com/rust-lang/rust-clippy/labels/L-bug%20%3Abeetle%3A
+[l-crash]: https://github.com/rust-lang/rust-clippy/labels/L-crash
+[l-bug]: https://github.com/rust-lang/rust-clippy/labels/L-bug
 [homu]: https://github.com/rust-lang/homu
 [homu_instructions]: https://buildbot2.rust-lang.org/homu/
 [homu_queue]: https://buildbot2.rust-lang.org/homu/queue/clippy
diff --git a/Cargo.toml b/Cargo.toml
index c7a3099b8ab..1ddcd18598d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,16 +31,14 @@ path = "src/driver.rs"
 # begin automatic update
 clippy_lints = { version = "0.0.212", path = "clippy_lints" }
 # end automatic update
-semver = "0.10"
+semver = "0.11"
 rustc_tools_util = { version = "0.2.0", path = "rustc_tools_util"}
 tempfile = { version = "3.1.0", optional = true }
-lazy_static = "1.0"
 
 [dev-dependencies]
-cargo_metadata = "0.11.1"
+cargo_metadata = "0.12"
 compiletest_rs = { version = "0.5.0", features = ["tmp"] }
 tester = "0.7"
-lazy_static = "1.0"
 clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }
 serde = { version = "1.0", features = ["derive"] }
 derive-new = "0.5"
diff --git a/README.md b/README.md
index 62a8be0abf2..e1b3c84d691 100644
--- a/README.md
+++ b/README.md
@@ -169,12 +169,33 @@ You can add options to your code to `allow`/`warn`/`deny` Clippy lints:
 
 Note: `deny` produces errors instead of warnings.
 
-If you do not want to include your lint levels in your code, you can globally enable/disable lints by passing extra
-flags to Clippy during the run: `cargo clippy -- -A clippy::lint_name` will run Clippy with `lint_name` disabled and
-`cargo clippy -- -W clippy::lint_name` will run it with that enabled. This also works with lint groups. For example you
-can run Clippy with warnings for all lints enabled: `cargo clippy -- -W clippy::pedantic`
+If you do not want to include your lint levels in your code, you can globally enable/disable lints
+by passing extra flags to Clippy during the run:
+
+To disable `lint_name`, run
+
+```terminal
+cargo clippy -- -A clippy::lint_name
+```
+
+And to enable `lint_name`, run
+
+```terminal
+cargo clippy -- -W clippy::lint_name
+```
+
+This also works with lint groups. For example you
+can run Clippy with warnings for all lints enabled: 
+```terminal
+cargo clippy -- -W clippy::pedantic
+```
+
 If you care only about a single lint, you can allow all others and then explicitly reenable
-the lint(s) you are interested in: `cargo clippy -- -Aclippy::all -Wclippy::useless_format -Wclippy::...`
+the lint(s) you are interested in:
+```terminal
+cargo clippy -- -A clippy::all -W clippy::useless_format -W clippy::...
+```
+Note that if you've run clippy before, this may only take effect after you've modified a file or ran `cargo clean`.
 
 ## Contributing
 
diff --git a/clippy_dev/src/update_lints.rs b/clippy_dev/src/update_lints.rs
index a9a70929942..556b67e0b37 100644
--- a/clippy_dev/src/update_lints.rs
+++ b/clippy_dev/src/update_lints.rs
@@ -29,7 +29,7 @@ pub fn run(update_mode: UpdateMode) {
         false,
         update_mode == UpdateMode::Change,
         || {
-            format!("pub static ref ALL_LINTS: Vec<Lint> = vec!{:#?};", sorted_usable_lints)
+            format!("vec!{:#?}", sorted_usable_lints)
                 .lines()
                 .map(ToString::to_string)
                 .collect::<Vec<_>>()
diff --git a/clippy_lints/Cargo.toml b/clippy_lints/Cargo.toml
index fcf817b82c8..d9471d25197 100644
--- a/clippy_lints/Cargo.toml
+++ b/clippy_lints/Cargo.toml
@@ -17,7 +17,7 @@ keywords = ["clippy", "lint", "plugin"]
 edition = "2018"
 
 [dependencies]
-cargo_metadata = "0.11.1"
+cargo_metadata = "0.12"
 if_chain = "1.0.0"
 itertools = "0.9"
 pulldown-cmark = { version = "0.8", default-features = false }
@@ -27,7 +27,7 @@ serde = { version = "1.0", features = ["derive"] }
 smallvec = { version = "1", features = ["union"] }
 toml = "0.5.3"
 unicode-normalization = "0.1"
-semver = "0.10.0"
+semver = "0.11"
 # NOTE: cargo requires serde feat in its url dep
 # see <https://github.com/rust-lang/rust/pull/63587#issuecomment-522343864>
 url = { version =  "2.1.0", features = ["serde"] }
diff --git a/clippy_lints/src/consts.rs b/clippy_lints/src/consts.rs
index 062c9bd2d9e..c5e33b288a9 100644
--- a/clippy_lints/src/consts.rs
+++ b/clippy_lints/src/consts.rs
@@ -40,6 +40,8 @@ pub enum Constant {
     Tuple(Vec<Constant>),
     /// A raw pointer.
     RawPtr(u128),
+    /// A reference
+    Ref(Box<Constant>),
     /// A literal with syntax error.
     Err(Symbol),
 }
@@ -66,6 +68,7 @@ impl PartialEq for Constant {
             (&Self::Bool(l), &Self::Bool(r)) => l == r,
             (&Self::Vec(ref l), &Self::Vec(ref r)) | (&Self::Tuple(ref l), &Self::Tuple(ref r)) => l == r,
             (&Self::Repeat(ref lv, ref ls), &Self::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
+            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => *lb == *rb,
             // TODO: are there inter-type equalities?
             _ => false,
         }
@@ -110,6 +113,9 @@ impl Hash for Constant {
             Self::RawPtr(u) => {
                 u.hash(state);
             },
+            Self::Ref(ref r) => {
+                r.hash(state);
+            },
             Self::Err(ref s) => {
                 s.hash(state);
             },
@@ -144,6 +150,7 @@ impl Constant {
                     x => x,
                 }
             },
+            (&Self::Ref(ref lb), &Self::Ref(ref rb)) => Self::partial_cmp(tcx, cmp_type, lb, rb),
             // TODO: are there any useful inter-type orderings?
             _ => None,
         }
@@ -239,7 +246,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
             ExprKind::Unary(op, ref operand) => self.expr(operand).and_then(|o| match op {
                 UnOp::UnNot => self.constant_not(&o, self.typeck_results.expr_ty(e)),
                 UnOp::UnNeg => self.constant_negate(&o, self.typeck_results.expr_ty(e)),
-                UnOp::UnDeref => Some(o),
+                UnOp::UnDeref => Some(if let Constant::Ref(r) = o { *r } else { o }),
             }),
             ExprKind::Binary(op, ref left, ref right) => self.binop(op, left, right),
             ExprKind::Call(ref callee, ref args) => {
@@ -269,6 +276,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
                 }
             },
             ExprKind::Index(ref arr, ref index) => self.index(arr, index),
+            ExprKind::AddrOf(_, _, ref inner) => self.expr(inner).map(|r| Constant::Ref(Box::new(r))),
             // TODO: add other expressions.
             _ => None,
         }
diff --git a/clippy_lints/src/copies.rs b/clippy_lints/src/copies.rs
index 10a64769585..6c969c3ead0 100644
--- a/clippy_lints/src/copies.rs
+++ b/clippy_lints/src/copies.rs
@@ -1,4 +1,4 @@
-use crate::utils::{eq_expr_value, SpanlessEq, SpanlessHash};
+use crate::utils::{eq_expr_value, in_macro, SpanlessEq, SpanlessHash};
 use crate::utils::{get_parent_expr, higher, if_sequence, snippet, span_lint_and_note, span_lint_and_then};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::{Arm, Block, Expr, ExprKind, MatchSource, Pat, PatKind};
@@ -220,6 +220,10 @@ fn lint_same_fns_in_if_cond(cx: &LateContext<'_>, conds: &[&Expr<'_>]) {
     };
 
     let eq: &dyn Fn(&&Expr<'_>, &&Expr<'_>) -> bool = &|&lhs, &rhs| -> bool {
+        // Do not lint if any expr originates from a macro
+        if in_macro(lhs.span) || in_macro(rhs.span) {
+            return false;
+        }
         // Do not spawn warning if `IFS_SAME_COND` already produced it.
         if eq_expr_value(cx, lhs, rhs) {
             return false;
diff --git a/clippy_lints/src/doc.rs b/clippy_lints/src/doc.rs
index 62bb70af06e..07f604cf714 100644
--- a/clippy_lints/src/doc.rs
+++ b/clippy_lints/src/doc.rs
@@ -32,6 +32,11 @@ declare_clippy_lint! {
     /// **Known problems:** Lots of bad docs won’t be fixed, what the lint checks
     /// for is limited, and there are still false positives.
     ///
+    /// In addition, when writing documentation comments, including `[]` brackets
+    /// inside a link text would trip the parser. Therfore, documenting link with
+    /// `[`SmallVec<[T; INLINE_CAPACITY]>`]` and then [`SmallVec<[T; INLINE_CAPACITY]>`]: SmallVec
+    /// would fail.
+    ///
     /// **Examples:**
     /// ```rust
     /// /// Do something with the foo_bar parameter. See also
@@ -39,6 +44,14 @@ declare_clippy_lint! {
     /// // ^ `foo_bar` and `that::other::module::foo` should be ticked.
     /// fn doit(foo_bar: usize) {}
     /// ```
+    ///
+    /// ```rust
+    /// // Link text with `[]` brackets should be written as following:
+    /// /// Consume the array and return the inner
+    /// /// [`SmallVec<[T; INLINE_CAPACITY]>`][SmallVec].
+    /// /// [SmallVec]: SmallVec
+    /// fn main() {}
+    /// ```
     pub DOC_MARKDOWN,
     pedantic,
     "presence of `_`, `::` or camel-case outside backticks in documentation"
diff --git a/clippy_lints/src/eq_op.rs b/clippy_lints/src/eq_op.rs
index e16ec783fab..3201adbf9a0 100644
--- a/clippy_lints/src/eq_op.rs
+++ b/clippy_lints/src/eq_op.rs
@@ -1,8 +1,10 @@
 use crate::utils::{
-    eq_expr_value, implements_trait, in_macro, is_copy, multispan_sugg, snippet, span_lint, span_lint_and_then,
+    eq_expr_value, higher, implements_trait, in_macro, is_copy, is_expn_of, multispan_sugg, snippet, span_lint,
+    span_lint_and_then,
 };
+use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOp, BinOpKind, BorrowKind, Expr, ExprKind};
+use rustc_hir::{BinOp, BinOpKind, BorrowKind, Expr, ExprKind, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -23,6 +25,12 @@ declare_clippy_lint! {
     /// # let x = 1;
     /// if x + 1 == x + 1 {}
     /// ```
+    /// or
+    /// ```rust
+    /// # let a = 3;
+    /// # let b = 4;
+    /// assert_eq!(a, a);
+    /// ```
     pub EQ_OP,
     correctness,
     "equal operands on both sides of a comparison or bitwise combination (e.g., `x == x`)"
@@ -52,9 +60,34 @@ declare_clippy_lint! {
 
 declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);
 
+const ASSERT_MACRO_NAMES: [&str; 4] = ["assert_eq", "assert_ne", "debug_assert_eq", "debug_assert_ne"];
+
 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 {
+            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 Some(macro_args) = higher::extract_assert_macro_args(matchexpr);
+                        if macro_args.len() == 2;
+                        let (lhs, rhs) = (macro_args[0], macro_args[1]);
+                        if eq_expr_value(cx, lhs, rhs);
+
+                        then {
+                            span_lint(
+                                cx,
+                                EQ_OP,
+                                lhs.span.to(rhs.span),
+                                &format!("identical args used in this `{}!` macro call", amn),
+                            );
+                        }
+                    }
+                }
+            }
+        }
         if let ExprKind::Binary(op, ref left, ref right) = e.kind {
             if e.span.from_expansion() {
                 return;
diff --git a/clippy_lints/src/format.rs b/clippy_lints/src/format.rs
index d6541010bca..26da058598e 100644
--- a/clippy_lints/src/format.rs
+++ b/clippy_lints/src/format.rs
@@ -1,6 +1,6 @@
 use crate::utils::paths;
 use crate::utils::{
-    is_expn_of, is_type_diagnostic_item, last_path_segment, match_def_path, match_function_call, snippet,
+    is_expn_of, is_type_diagnostic_item, last_path_segment, match_def_path, match_function_call, snippet, snippet_opt,
     span_lint_and_then,
 };
 use if_chain::if_chain;
@@ -132,7 +132,11 @@ fn on_new_v1<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Strin
         then {
             // `format!("foo")` expansion contains `match () { () => [], }`
             if tup.is_empty() {
-                return Some(format!("{:?}.to_string()", s.as_str()));
+                if let Some(s_src) = snippet_opt(cx, lit.span) {
+                    // Simulate macro expansion, converting {{ and }} to { and }.
+                    let s_expand = s_src.replace("{{", "{").replace("}}", "}");
+                    return Some(format!("{}.to_string()", s_expand))
+                }
             } else if s.as_str().is_empty() {
                 return on_argumentv1_new(cx, &tup[0], arms);
             }
diff --git a/clippy_lints/src/functions.rs b/clippy_lints/src/functions.rs
index 50b39cf4ea7..fd45a6da61c 100644
--- a/clippy_lints/src/functions.rs
+++ b/clippy_lints/src/functions.rs
@@ -1,8 +1,9 @@
 use crate::utils::{
-    attr_by_name, attrs::is_proc_macro, is_must_use_ty, is_trait_impl_item, iter_input_pats, match_def_path,
-    must_use_attr, qpath_res, return_ty, snippet, snippet_opt, span_lint, span_lint_and_help, span_lint_and_then,
-    trait_ref_of_method, type_is_unsafe_function,
+    attr_by_name, attrs::is_proc_macro, is_must_use_ty, is_trait_impl_item, is_type_diagnostic_item, iter_input_pats,
+    last_path_segment, match_def_path, must_use_attr, qpath_res, return_ty, snippet, snippet_opt, span_lint,
+    span_lint_and_help, span_lint_and_then, trait_ref_of_method, type_is_unsafe_function,
 };
+use if_chain::if_chain;
 use rustc_ast::ast::Attribute;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
@@ -16,6 +17,7 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 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.
@@ -169,6 +171,52 @@ declare_clippy_lint! {
     "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,
@@ -188,6 +236,7 @@ impl_lint_pass!(Functions => [
     MUST_USE_UNIT,
     DOUBLE_MUST_USE,
     MUST_USE_CANDIDATE,
+    RESULT_UNIT_ERR,
 ]);
 
 impl<'tcx> LateLintPass<'tcx> for Functions {
@@ -233,15 +282,16 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
         let attr = must_use_attr(&item.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 {
-                let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
                 check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
                 return;
             }
-            if cx.access_levels.is_exported(item.hir_id)
-                && !is_proc_macro(cx.sess(), &item.attrs)
-                && attr_by_name(&item.attrs, "no_mangle").is_none()
-            {
+            if is_public && !is_proc_macro(cx.sess(), &item.attrs) && attr_by_name(&item.attrs, "no_mangle").is_none() {
                 check_must_use_candidate(
                     cx,
                     &sig.decl,
@@ -257,11 +307,15 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
 
     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 attr = must_use_attr(&item.attrs);
             if let Some(attr) = attr {
-                let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
                 check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
-            } else if cx.access_levels.is_exported(item.hir_id)
+            } else if is_public
                 && !is_proc_macro(cx.sess(), &item.attrs)
                 && trait_ref_of_method(cx, item.hir_id).is_none()
             {
@@ -284,18 +338,21 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
             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 attr = must_use_attr(&item.attrs);
             if let Some(attr) = attr {
-                let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
                 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() && cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(cx.sess(), &item.attrs)
-                {
+                if attr.is_none() && is_public && !is_proc_macro(cx.sess(), &item.attrs) {
                     check_must_use_candidate(
                         cx,
                         &sig.decl,
@@ -411,6 +468,29 @@ impl<'tcx> Functions {
     }
 }
 
+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;
+        if let hir::TyKind::Path(ref qpath) = ty.kind;
+        if is_type_diagnostic_item(cx, hir_ty_to_ty(cx.tcx, ty), sym!(result_type));
+        if let Some(ref args) = last_path_segment(qpath).args;
+        if let [_, hir::GenericArg::Type(ref err_ty)] = args.args;
+        if let hir::TyKind::Tup(t) = err_ty.kind;
+        if t.is_empty();
+        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<'_>,
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 93b5d9e178c..d4d2f92a6a6 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -234,6 +234,7 @@ mod main_recursion;
 mod manual_async_fn;
 mod manual_non_exhaustive;
 mod manual_strip;
+mod manual_unwrap_or;
 mod map_clone;
 mod map_err_ignore;
 mod map_identity;
@@ -281,6 +282,7 @@ mod path_buf_push_overwrite;
 mod pattern_type_mismatch;
 mod precedence;
 mod ptr;
+mod ptr_eq;
 mod ptr_offset_with_cast;
 mod question_mark;
 mod ranges;
@@ -581,6 +583,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &functions::MUST_USE_CANDIDATE,
         &functions::MUST_USE_UNIT,
         &functions::NOT_UNSAFE_PTR_ARG_DEREF,
+        &functions::RESULT_UNIT_ERR,
         &functions::TOO_MANY_ARGUMENTS,
         &functions::TOO_MANY_LINES,
         &future_not_send::FUTURE_NOT_SEND,
@@ -638,6 +641,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &manual_async_fn::MANUAL_ASYNC_FN,
         &manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE,
         &manual_strip::MANUAL_STRIP,
+        &manual_unwrap_or::MANUAL_UNWRAP_OR,
         &map_clone::MAP_CLONE,
         &map_err_ignore::MAP_ERR_IGNORE,
         &map_identity::MAP_IDENTITY,
@@ -778,6 +782,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &ptr::CMP_NULL,
         &ptr::MUT_FROM_REF,
         &ptr::PTR_ARG,
+        &ptr_eq::PTR_EQ,
         &ptr_offset_with_cast::PTR_OFFSET_WITH_CAST,
         &question_mark::QUESTION_MARK,
         &ranges::RANGE_MINUS_ONE,
@@ -916,6 +921,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     let verbose_bit_mask_threshold = conf.verbose_bit_mask_threshold;
     store.register_late_pass(move || box bit_mask::BitMask::new(verbose_bit_mask_threshold));
     store.register_late_pass(|| box ptr::Ptr);
+    store.register_late_pass(|| box ptr_eq::PtrEq);
     store.register_late_pass(|| box needless_bool::NeedlessBool);
     store.register_late_pass(|| box needless_bool::BoolComparison);
     store.register_late_pass(|| box approx_const::ApproxConstant);
@@ -1122,6 +1128,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| box repeat_once::RepeatOnce);
     store.register_late_pass(|| box unwrap_in_result::UnwrapInResult);
     store.register_late_pass(|| box self_assignment::SelfAssignment);
+    store.register_late_pass(|| box manual_unwrap_or::ManualUnwrapOr);
     store.register_late_pass(|| box float_equality_without_abs::FloatEqualityWithoutAbs);
     store.register_late_pass(|| box async_yields_async::AsyncYieldsAsync);
     store.register_late_pass(|| box manual_strip::ManualStrip);
@@ -1324,6 +1331,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&functions::DOUBLE_MUST_USE),
         LintId::of(&functions::MUST_USE_UNIT),
         LintId::of(&functions::NOT_UNSAFE_PTR_ARG_DEREF),
+        LintId::of(&functions::RESULT_UNIT_ERR),
         LintId::of(&functions::TOO_MANY_ARGUMENTS),
         LintId::of(&get_last_with_len::GET_LAST_WITH_LEN),
         LintId::of(&identity_op::IDENTITY_OP),
@@ -1362,6 +1370,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&manual_async_fn::MANUAL_ASYNC_FN),
         LintId::of(&manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
         LintId::of(&manual_strip::MANUAL_STRIP),
+        LintId::of(&manual_unwrap_or::MANUAL_UNWRAP_OR),
         LintId::of(&map_clone::MAP_CLONE),
         LintId::of(&map_identity::MAP_IDENTITY),
         LintId::of(&map_unit_fn::OPTION_MAP_UNIT_FN),
@@ -1457,6 +1466,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&ptr::CMP_NULL),
         LintId::of(&ptr::MUT_FROM_REF),
         LintId::of(&ptr::PTR_ARG),
+        LintId::of(&ptr_eq::PTR_EQ),
         LintId::of(&ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
         LintId::of(&question_mark::QUESTION_MARK),
         LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
@@ -1554,6 +1564,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&formatting::SUSPICIOUS_UNARY_OP_FORMATTING),
         LintId::of(&functions::DOUBLE_MUST_USE),
         LintId::of(&functions::MUST_USE_UNIT),
+        LintId::of(&functions::RESULT_UNIT_ERR),
         LintId::of(&if_let_some_result::IF_LET_SOME_RESULT),
         LintId::of(&inherent_to_string::INHERENT_TO_STRING),
         LintId::of(&len_zero::LEN_WITHOUT_IS_EMPTY),
@@ -1611,6 +1622,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&panic_unimplemented::PANIC_PARAMS),
         LintId::of(&ptr::CMP_NULL),
         LintId::of(&ptr::PTR_ARG),
+        LintId::of(&ptr_eq::PTR_EQ),
         LintId::of(&question_mark::QUESTION_MARK),
         LintId::of(&redundant_field_names::REDUNDANT_FIELD_NAMES),
         LintId::of(&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
@@ -1654,6 +1666,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&loops::MUT_RANGE_BOUND),
         LintId::of(&loops::WHILE_LET_LOOP),
         LintId::of(&manual_strip::MANUAL_STRIP),
+        LintId::of(&manual_unwrap_or::MANUAL_UNWRAP_OR),
         LintId::of(&map_identity::MAP_IDENTITY),
         LintId::of(&map_unit_fn::OPTION_MAP_UNIT_FN),
         LintId::of(&map_unit_fn::RESULT_MAP_UNIT_FN),
diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 4fdcaca8f60..63d7e3176b1 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -5,9 +5,8 @@ use crate::utils::usage::{is_unused, mutated_variables};
 use crate::utils::{
     contains_name, get_enclosing_block, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
     is_integer_const, is_no_std_crate, is_refutable, is_type_diagnostic_item, last_path_segment, match_trait_method,
-    match_type, match_var, multispan_sugg, qpath_res, snippet, snippet_opt, snippet_with_applicability,
-    snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, sugg,
-    SpanlessEq,
+    match_type, match_var, multispan_sugg, qpath_res, snippet, snippet_with_applicability, snippet_with_macro_callsite,
+    span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, sugg, SpanlessEq,
 };
 use if_chain::if_chain;
 use rustc_ast::ast;
@@ -770,15 +769,28 @@ fn check_for_loop<'tcx>(
     body: &'tcx Expr<'_>,
     expr: &'tcx Expr<'_>,
 ) {
-    check_for_loop_range(cx, pat, arg, body, expr);
+    let is_manual_memcpy_triggered = detect_manual_memcpy(cx, pat, arg, body, expr);
+    if !is_manual_memcpy_triggered {
+        check_for_loop_range(cx, pat, arg, body, expr);
+        check_for_loop_explicit_counter(cx, pat, arg, body, expr);
+    }
     check_for_loop_arg(cx, pat, arg, expr);
-    check_for_loop_explicit_counter(cx, pat, arg, body, expr);
     check_for_loop_over_map_kv(cx, pat, arg, body, expr);
     check_for_mut_range_bound(cx, arg, body);
-    detect_manual_memcpy(cx, pat, arg, body, expr);
     detect_same_item_push(cx, pat, arg, body, expr);
 }
 
+// this function assumes the given expression is a `for` loop.
+fn get_span_of_entire_for_loop(expr: &Expr<'_>) -> Span {
+    // for some reason this is the only way to get the `Span`
+    // of the entire `for` loop
+    if let ExprKind::Match(_, arms, _) = &expr.kind {
+        arms[0].body.span
+    } else {
+        unreachable!()
+    }
+}
+
 fn same_var<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, var: HirId) -> bool {
     if_chain! {
         if let ExprKind::Path(qpath) = &expr.kind;
@@ -794,36 +806,131 @@ fn same_var<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, var: HirId) -> bool {
     }
 }
 
-#[derive(Clone, Copy)]
-enum OffsetSign {
-    Positive,
-    Negative,
+/// a wrapper of `Sugg`. Besides what `Sugg` do, this removes unnecessary `0`;
+/// and also, it avoids subtracting a variable from the same one by replacing it with `0`.
+/// it exists for the convenience of the overloaded operators while normal functions can do the
+/// same.
+#[derive(Clone)]
+struct MinifyingSugg<'a>(Sugg<'a>);
+
+impl<'a> MinifyingSugg<'a> {
+    fn as_str(&self) -> &str {
+        let Sugg::NonParen(s) | Sugg::MaybeParen(s) | Sugg::BinOp(_, s) = &self.0;
+        s.as_ref()
+    }
+
+    fn into_sugg(self) -> Sugg<'a> {
+        self.0
+    }
+}
+
+impl<'a> From<Sugg<'a>> for MinifyingSugg<'a> {
+    fn from(sugg: Sugg<'a>) -> Self {
+        Self(sugg)
+    }
+}
+
+impl std::ops::Add for &MinifyingSugg<'static> {
+    type Output = MinifyingSugg<'static>;
+    fn add(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
+        match (self.as_str(), rhs.as_str()) {
+            ("0", _) => rhs.clone(),
+            (_, "0") => self.clone(),
+            (_, _) => (&self.0 + &rhs.0).into(),
+        }
+    }
+}
+
+impl std::ops::Sub for &MinifyingSugg<'static> {
+    type Output = MinifyingSugg<'static>;
+    fn sub(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
+        match (self.as_str(), rhs.as_str()) {
+            (_, "0") => self.clone(),
+            ("0", _) => (-rhs.0.clone()).into(),
+            (x, y) if x == y => sugg::ZERO.into(),
+            (_, _) => (&self.0 - &rhs.0).into(),
+        }
+    }
+}
+
+impl std::ops::Add<&MinifyingSugg<'static>> for MinifyingSugg<'static> {
+    type Output = MinifyingSugg<'static>;
+    fn add(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
+        match (self.as_str(), rhs.as_str()) {
+            ("0", _) => rhs.clone(),
+            (_, "0") => self,
+            (_, _) => (self.0 + &rhs.0).into(),
+        }
+    }
 }
 
+impl std::ops::Sub<&MinifyingSugg<'static>> for MinifyingSugg<'static> {
+    type Output = MinifyingSugg<'static>;
+    fn sub(self, rhs: &MinifyingSugg<'static>) -> MinifyingSugg<'static> {
+        match (self.as_str(), rhs.as_str()) {
+            (_, "0") => self,
+            ("0", _) => (-rhs.0.clone()).into(),
+            (x, y) if x == y => sugg::ZERO.into(),
+            (_, _) => (self.0 - &rhs.0).into(),
+        }
+    }
+}
+
+/// a wrapper around `MinifyingSugg`, which carries a operator like currying
+/// so that the suggested code become more efficient (e.g. `foo + -bar` `foo - bar`).
 struct Offset {
-    value: String,
+    value: MinifyingSugg<'static>,
     sign: OffsetSign,
 }
 
+#[derive(Clone, Copy)]
+enum OffsetSign {
+    Positive,
+    Negative,
+}
+
 impl Offset {
-    fn negative(value: String) -> Self {
+    fn negative(value: Sugg<'static>) -> Self {
         Self {
-            value,
+            value: value.into(),
             sign: OffsetSign::Negative,
         }
     }
 
-    fn positive(value: String) -> Self {
+    fn positive(value: Sugg<'static>) -> Self {
         Self {
-            value,
+            value: value.into(),
             sign: OffsetSign::Positive,
         }
     }
+
+    fn empty() -> Self {
+        Self::positive(sugg::ZERO)
+    }
 }
 
-struct FixedOffsetVar<'hir> {
-    var: &'hir Expr<'hir>,
-    offset: Offset,
+fn apply_offset(lhs: &MinifyingSugg<'static>, rhs: &Offset) -> MinifyingSugg<'static> {
+    match rhs.sign {
+        OffsetSign::Positive => lhs + &rhs.value,
+        OffsetSign::Negative => lhs - &rhs.value,
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+enum StartKind<'hir> {
+    Range,
+    Counter { initializer: &'hir Expr<'hir> },
+}
+
+struct IndexExpr<'hir> {
+    base: &'hir Expr<'hir>,
+    idx: StartKind<'hir>,
+    idx_offset: Offset,
+}
+
+struct Start<'hir> {
+    id: HirId,
+    kind: StartKind<'hir>,
 }
 
 fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'_>) -> bool {
@@ -846,14 +953,28 @@ fn fetch_cloned_expr<'tcx>(expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
     }
 }
 
-fn get_offset<'tcx>(cx: &LateContext<'tcx>, idx: &Expr<'_>, var: HirId) -> Option<Offset> {
-    fn extract_offset<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>, var: HirId) -> Option<String> {
+fn get_details_from_idx<'tcx>(
+    cx: &LateContext<'tcx>,
+    idx: &Expr<'_>,
+    starts: &[Start<'tcx>],
+) -> Option<(StartKind<'tcx>, Offset)> {
+    fn get_start<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>, starts: &[Start<'tcx>]) -> Option<StartKind<'tcx>> {
+        starts.iter().find_map(|start| {
+            if same_var(cx, e, start.id) {
+                Some(start.kind)
+            } else {
+                None
+            }
+        })
+    }
+
+    fn get_offset<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>, starts: &[Start<'tcx>]) -> Option<Sugg<'static>> {
         match &e.kind {
             ExprKind::Lit(l) => match l.node {
-                ast::LitKind::Int(x, _ty) => Some(x.to_string()),
+                ast::LitKind::Int(x, _ty) => Some(Sugg::NonParen(x.to_string().into())),
                 _ => None,
             },
-            ExprKind::Path(..) if !same_var(cx, e, var) => Some(snippet_opt(cx, e.span).unwrap_or_else(|| "??".into())),
+            ExprKind::Path(..) if get_start(cx, e, starts).is_none() => Some(Sugg::hir(cx, e, "???")),
             _ => None,
         }
     }
@@ -861,55 +982,89 @@ fn get_offset<'tcx>(cx: &LateContext<'tcx>, idx: &Expr<'_>, var: HirId) -> Optio
     match idx.kind {
         ExprKind::Binary(op, lhs, rhs) => match op.node {
             BinOpKind::Add => {
-                let offset_opt = if same_var(cx, lhs, var) {
-                    extract_offset(cx, rhs, var)
-                } else if same_var(cx, rhs, var) {
-                    extract_offset(cx, lhs, var)
-                } else {
-                    None
-                };
+                let offset_opt = get_start(cx, lhs, starts)
+                    .and_then(|s| get_offset(cx, rhs, starts).map(|o| (s, o)))
+                    .or_else(|| get_start(cx, rhs, starts).and_then(|s| get_offset(cx, lhs, starts).map(|o| (s, o))));
 
-                offset_opt.map(Offset::positive)
+                offset_opt.map(|(s, o)| (s, Offset::positive(o)))
+            },
+            BinOpKind::Sub => {
+                get_start(cx, lhs, starts).and_then(|s| get_offset(cx, rhs, starts).map(|o| (s, Offset::negative(o))))
             },
-            BinOpKind::Sub if same_var(cx, lhs, var) => extract_offset(cx, rhs, var).map(Offset::negative),
             _ => None,
         },
-        ExprKind::Path(..) if same_var(cx, idx, var) => Some(Offset::positive("0".into())),
+        ExprKind::Path(..) => get_start(cx, idx, starts).map(|s| (s, Offset::empty())),
         _ => None,
     }
 }
 
-fn get_assignments<'tcx>(body: &'tcx Expr<'tcx>) -> impl Iterator<Item = Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)>> {
-    fn get_assignment<'tcx>(e: &'tcx Expr<'tcx>) -> Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> {
-        if let ExprKind::Assign(lhs, rhs, _) = e.kind {
-            Some((lhs, rhs))
-        } else {
-            None
-        }
+fn get_assignment<'tcx>(e: &'tcx Expr<'tcx>) -> Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)> {
+    if let ExprKind::Assign(lhs, rhs, _) = e.kind {
+        Some((lhs, rhs))
+    } else {
+        None
     }
+}
 
-    // This is one of few ways to return different iterators
-    // derived from: https://stackoverflow.com/questions/29760668/conditionally-iterate-over-one-of-several-possible-iterators/52064434#52064434
-    let mut iter_a = None;
-    let mut iter_b = None;
+/// Get assignments from the given block.
+/// The returned iterator yields `None` if no assignment expressions are there,
+/// filtering out the increments of the given whitelisted loop counters;
+/// because its job is to make sure there's nothing other than assignments and the increments.
+fn get_assignments<'a: 'c, 'tcx: 'c, 'c>(
+    cx: &'a LateContext<'tcx>,
+    Block { stmts, expr, .. }: &'tcx Block<'tcx>,
+    loop_counters: &'c [Start<'tcx>],
+) -> impl Iterator<Item = Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)>> + 'c {
+    // As the `filter` and `map` below do different things, I think putting together
+    // just increases complexity. (cc #3188 and #4193)
+    #[allow(clippy::filter_map)]
+    stmts
+        .iter()
+        .filter_map(move |stmt| match stmt.kind {
+            StmtKind::Local(..) | StmtKind::Item(..) => None,
+            StmtKind::Expr(e) | StmtKind::Semi(e) => Some(e),
+        })
+        .chain((*expr).into_iter())
+        .filter(move |e| {
+            if let ExprKind::AssignOp(_, place, _) = e.kind {
+                !loop_counters
+                    .iter()
+                    // skip the first item which should be `StartKind::Range`
+                    // this makes it possible to use the slice with `StartKind::Range` in the same iterator loop.
+                    .skip(1)
+                    .any(|counter| same_var(cx, place, counter.id))
+            } else {
+                true
+            }
+        })
+        .map(get_assignment)
+}
 
-    if let ExprKind::Block(b, _) = body.kind {
-        let Block { stmts, expr, .. } = *b;
+fn get_loop_counters<'a, 'tcx>(
+    cx: &'a LateContext<'tcx>,
+    body: &'tcx Block<'tcx>,
+    expr: &'tcx Expr<'_>,
+) -> Option<impl Iterator<Item = Start<'tcx>> + 'a> {
+    // Look for variables that are incremented once per loop iteration.
+    let mut increment_visitor = IncrementVisitor::new(cx);
+    walk_block(&mut increment_visitor, body);
 
-        iter_a = stmts
-            .iter()
-            .filter_map(|stmt| match stmt.kind {
-                StmtKind::Local(..) | StmtKind::Item(..) => None,
-                StmtKind::Expr(e) | StmtKind::Semi(e) => Some(e),
+    // For each candidate, check the parent block to see if
+    // it's initialized to zero at the start of the loop.
+    get_enclosing_block(&cx, expr.hir_id).and_then(|block| {
+        increment_visitor
+            .into_results()
+            .filter_map(move |var_id| {
+                let mut initialize_visitor = InitializeVisitor::new(cx, expr, var_id);
+                walk_block(&mut initialize_visitor, block);
+
+                initialize_visitor.get_result().map(|(_, initializer)| Start {
+                    id: var_id,
+                    kind: StartKind::Counter { initializer },
+                })
             })
-            .chain(expr.into_iter())
-            .map(get_assignment)
             .into()
-    } else {
-        iter_b = Some(get_assignment(body))
-    }
-
-    iter_a.into_iter().flatten().chain(iter_b.into_iter())
+    })
 }
 
 fn build_manual_memcpy_suggestion<'tcx>(
@@ -917,80 +1072,97 @@ fn build_manual_memcpy_suggestion<'tcx>(
     start: &Expr<'_>,
     end: &Expr<'_>,
     limits: ast::RangeLimits,
-    dst_var: FixedOffsetVar<'_>,
-    src_var: FixedOffsetVar<'_>,
+    dst: &IndexExpr<'_>,
+    src: &IndexExpr<'_>,
 ) -> String {
-    fn print_sum(arg1: &str, arg2: &Offset) -> String {
-        match (arg1, &arg2.value[..], arg2.sign) {
-            ("0", "0", _) => "0".into(),
-            ("0", x, OffsetSign::Positive) | (x, "0", _) => x.into(),
-            ("0", x, OffsetSign::Negative) => format!("-{}", x),
-            (x, y, OffsetSign::Positive) => format!("({} + {})", x, y),
-            (x, y, OffsetSign::Negative) => {
-                if x == y {
-                    "0".into()
-                } else {
-                    format!("({} - {})", x, y)
-                }
-            },
-        }
-    }
-
-    fn print_offset(start_str: &str, inline_offset: &Offset) -> String {
-        let offset = print_sum(start_str, inline_offset);
+    fn print_offset(offset: MinifyingSugg<'static>) -> MinifyingSugg<'static> {
         if offset.as_str() == "0" {
-            "".into()
+            sugg::EMPTY.into()
         } else {
             offset
         }
     }
 
-    let print_limit = |end: &Expr<'_>, offset: Offset, var: &Expr<'_>| {
+    let print_limit = |end: &Expr<'_>, end_str: &str, base: &Expr<'_>, sugg: MinifyingSugg<'static>| {
         if_chain! {
             if let ExprKind::MethodCall(method, _, len_args, _) = end.kind;
             if method.ident.name == sym!(len);
             if len_args.len() == 1;
             if let Some(arg) = len_args.get(0);
-            if var_def_id(cx, arg) == var_def_id(cx, var);
+            if var_def_id(cx, arg) == var_def_id(cx, base);
             then {
-                match offset.sign {
-                    OffsetSign::Negative => format!("({} - {})", snippet(cx, end.span, "<src>.len()"), offset.value),
-                    OffsetSign::Positive => "".into(),
+                if sugg.as_str() == end_str {
+                    sugg::EMPTY.into()
+                } else {
+                    sugg
                 }
             } else {
-                let end_str = match limits {
+                match limits {
                     ast::RangeLimits::Closed => {
-                        let end = sugg::Sugg::hir(cx, end, "<count>");
-                        format!("{}", end + sugg::ONE)
+                        sugg + &sugg::ONE.into()
                     },
-                    ast::RangeLimits::HalfOpen => format!("{}", snippet(cx, end.span, "..")),
-                };
-
-                print_sum(&end_str, &offset)
+                    ast::RangeLimits::HalfOpen => sugg,
+                }
             }
         }
     };
 
-    let start_str = snippet(cx, start.span, "").to_string();
-    let dst_offset = print_offset(&start_str, &dst_var.offset);
-    let dst_limit = print_limit(end, dst_var.offset, dst_var.var);
-    let src_offset = print_offset(&start_str, &src_var.offset);
-    let src_limit = print_limit(end, src_var.offset, src_var.var);
+    let start_str = Sugg::hir(cx, start, "").into();
+    let end_str: MinifyingSugg<'_> = Sugg::hir(cx, end, "").into();
+
+    let print_offset_and_limit = |idx_expr: &IndexExpr<'_>| match idx_expr.idx {
+        StartKind::Range => (
+            print_offset(apply_offset(&start_str, &idx_expr.idx_offset)).into_sugg(),
+            print_limit(
+                end,
+                end_str.as_str(),
+                idx_expr.base,
+                apply_offset(&end_str, &idx_expr.idx_offset),
+            )
+            .into_sugg(),
+        ),
+        StartKind::Counter { initializer } => {
+            let counter_start = Sugg::hir(cx, initializer, "").into();
+            (
+                print_offset(apply_offset(&counter_start, &idx_expr.idx_offset)).into_sugg(),
+                print_limit(
+                    end,
+                    end_str.as_str(),
+                    idx_expr.base,
+                    apply_offset(&end_str, &idx_expr.idx_offset) + &counter_start - &start_str,
+                )
+                .into_sugg(),
+            )
+        },
+    };
+
+    let (dst_offset, dst_limit) = print_offset_and_limit(&dst);
+    let (src_offset, src_limit) = print_offset_and_limit(&src);
 
-    let dst_var_name = snippet_opt(cx, dst_var.var.span).unwrap_or_else(|| "???".into());
-    let src_var_name = snippet_opt(cx, src_var.var.span).unwrap_or_else(|| "???".into());
+    let dst_base_str = snippet(cx, dst.base.span, "???");
+    let src_base_str = snippet(cx, src.base.span, "???");
 
-    let dst = if dst_offset == "" && dst_limit == "" {
-        dst_var_name
+    let dst = if dst_offset == sugg::EMPTY && dst_limit == sugg::EMPTY {
+        dst_base_str
     } else {
-        format!("{}[{}..{}]", dst_var_name, dst_offset, dst_limit)
+        format!(
+            "{}[{}..{}]",
+            dst_base_str,
+            dst_offset.maybe_par(),
+            dst_limit.maybe_par()
+        )
+        .into()
     };
 
     format!(
-        "{}.clone_from_slice(&{}[{}..{}])",
-        dst, src_var_name, src_offset, src_limit
+        "{}.clone_from_slice(&{}[{}..{}]);",
+        dst,
+        src_base_str,
+        src_offset.maybe_par(),
+        src_limit.maybe_par()
     )
 }
+
 /// Checks for for loops that sequentially copy items from one slice-like
 /// object to another.
 fn detect_manual_memcpy<'tcx>(
@@ -999,7 +1171,7 @@ fn detect_manual_memcpy<'tcx>(
     arg: &'tcx Expr<'_>,
     body: &'tcx Expr<'_>,
     expr: &'tcx Expr<'_>,
-) {
+) -> bool {
     if let Some(higher::Range {
         start: Some(start),
         end: Some(end),
@@ -1008,32 +1180,53 @@ fn detect_manual_memcpy<'tcx>(
     {
         // the var must be a single name
         if let PatKind::Binding(_, canonical_id, _, _) = pat.kind {
-            // The only statements in the for loops can be indexed assignments from
-            // indexed retrievals.
-            let big_sugg = get_assignments(body)
+            let mut starts = vec![Start {
+                id: canonical_id,
+                kind: StartKind::Range,
+            }];
+
+            // This is one of few ways to return different iterators
+            // derived from: https://stackoverflow.com/questions/29760668/conditionally-iterate-over-one-of-several-possible-iterators/52064434#52064434
+            let mut iter_a = None;
+            let mut iter_b = None;
+
+            if let ExprKind::Block(block, _) = body.kind {
+                if let Some(loop_counters) = get_loop_counters(cx, block, expr) {
+                    starts.extend(loop_counters);
+                }
+                iter_a = Some(get_assignments(cx, block, &starts));
+            } else {
+                iter_b = Some(get_assignment(body));
+            }
+
+            let assignments = iter_a.into_iter().flatten().chain(iter_b.into_iter());
+
+            let big_sugg = assignments
+                // The only statements in the for loops can be indexed assignments from
+                // indexed retrievals (except increments of loop counters).
                 .map(|o| {
                     o.and_then(|(lhs, rhs)| {
                         let rhs = fetch_cloned_expr(rhs);
                         if_chain! {
-                            if let ExprKind::Index(seqexpr_left, idx_left) = lhs.kind;
-                            if let ExprKind::Index(seqexpr_right, idx_right) = rhs.kind;
-                            if is_slice_like(cx, cx.typeck_results().expr_ty(seqexpr_left))
-                                && is_slice_like(cx, cx.typeck_results().expr_ty(seqexpr_right));
-                            if let Some(offset_left) = get_offset(cx, &idx_left, canonical_id);
-                            if let Some(offset_right) = get_offset(cx, &idx_right, canonical_id);
+                            if let ExprKind::Index(base_left, idx_left) = lhs.kind;
+                            if let ExprKind::Index(base_right, idx_right) = rhs.kind;
+                            if is_slice_like(cx, cx.typeck_results().expr_ty(base_left))
+                                && is_slice_like(cx, cx.typeck_results().expr_ty(base_right));
+                            if let Some((start_left, offset_left)) = get_details_from_idx(cx, &idx_left, &starts);
+                            if let Some((start_right, offset_right)) = get_details_from_idx(cx, &idx_right, &starts);
 
                             // Source and destination must be different
-                            if var_def_id(cx, seqexpr_left) != var_def_id(cx, seqexpr_right);
+                            if var_def_id(cx, base_left) != var_def_id(cx, base_right);
                             then {
-                                Some((FixedOffsetVar { var: seqexpr_left, offset: offset_left },
-                                    FixedOffsetVar { var: seqexpr_right, offset: offset_right }))
+                                Some((IndexExpr { base: base_left, idx: start_left, idx_offset: offset_left },
+                                    IndexExpr { base: base_right, idx: start_right, idx_offset: offset_right }))
                             } else {
                                 None
                             }
                         }
                     })
                 })
-                .map(|o| o.map(|(dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, dst, src)))
+                .map(|o| o.map(|(dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, &dst, &src)))
                 .collect::<Option<Vec<_>>>()
                 .filter(|v| !v.is_empty())
                 .map(|v| v.join("\n    "));
@@ -1042,15 +1235,17 @@ fn detect_manual_memcpy<'tcx>(
                 span_lint_and_sugg(
                     cx,
                     MANUAL_MEMCPY,
-                    expr.span,
+                    get_span_of_entire_for_loop(expr),
                     "it looks like you're manually copying between slices",
                     "try replacing the loop by",
                     big_sugg,
                     Applicability::Unspecified,
                 );
+                return true;
             }
         }
     }
+    false
 }
 
 // Scans the body of the for loop and determines whether lint should be given
@@ -1533,6 +1728,9 @@ fn check_arg_type(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
     }
 }
 
+// To trigger the EXPLICIT_COUNTER_LOOP lint, a variable must be
+// incremented exactly once in the loop body, and initialized to zero
+// at the start of the loop.
 fn check_for_loop_explicit_counter<'tcx>(
     cx: &LateContext<'tcx>,
     pat: &'tcx Pat<'_>,
@@ -1541,40 +1739,23 @@ fn check_for_loop_explicit_counter<'tcx>(
     expr: &'tcx Expr<'_>,
 ) {
     // Look for variables that are incremented once per loop iteration.
-    let mut visitor = IncrementVisitor {
-        cx,
-        states: FxHashMap::default(),
-        depth: 0,
-        done: false,
-    };
-    walk_expr(&mut visitor, body);
+    let mut increment_visitor = IncrementVisitor::new(cx);
+    walk_expr(&mut increment_visitor, body);
 
     // For each candidate, check the parent block to see if
     // it's initialized to zero at the start of the loop.
     if let Some(block) = get_enclosing_block(&cx, expr.hir_id) {
-        for (id, _) in visitor.states.iter().filter(|&(_, v)| *v == VarState::IncrOnce) {
-            let mut visitor2 = InitializeVisitor {
-                cx,
-                end_expr: expr,
-                var_id: *id,
-                state: VarState::IncrOnce,
-                name: None,
-                depth: 0,
-                past_loop: false,
-            };
-            walk_block(&mut visitor2, block);
+        for id in increment_visitor.into_results() {
+            let mut initialize_visitor = InitializeVisitor::new(cx, expr, id);
+            walk_block(&mut initialize_visitor, block);
 
-            if visitor2.state == VarState::Warn {
-                if let Some(name) = visitor2.name {
+            if_chain! {
+                if let Some((name, initializer)) = initialize_visitor.get_result();
+                if is_integer_const(cx, initializer, 0);
+                then {
                     let mut applicability = Applicability::MachineApplicable;
 
-                    // for some reason this is the only way to get the `Span`
-                    // of the entire `for` loop
-                    let for_span = if let ExprKind::Match(_, arms, _) = &expr.kind {
-                        arms[0].body.span
-                    } else {
-                        unreachable!()
-                    };
+                    let for_span = get_span_of_entire_for_loop(expr);
 
                     span_lint_and_sugg(
                         cx,
@@ -2127,26 +2308,42 @@ fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
     }
 }
 
-// To trigger the EXPLICIT_COUNTER_LOOP lint, a variable must be
-// incremented exactly once in the loop body, and initialized to zero
-// at the start of the loop.
 #[derive(Debug, PartialEq)]
-enum VarState {
+enum IncrementVisitorVarState {
     Initial,  // Not examined yet
     IncrOnce, // Incremented exactly once, may be a loop counter
-    Declared, // Declared but not (yet) initialized to zero
-    Warn,
     DontWarn,
 }
 
 /// Scan a for loop for variables that are incremented exactly once and not used after that.
 struct IncrementVisitor<'a, 'tcx> {
-    cx: &'a LateContext<'tcx>,          // context reference
-    states: FxHashMap<HirId, VarState>, // incremented variables
-    depth: u32,                         // depth of conditional expressions
+    cx: &'a LateContext<'tcx>,                          // context reference
+    states: FxHashMap<HirId, IncrementVisitorVarState>, // incremented variables
+    depth: u32,                                         // depth of conditional expressions
     done: bool,
 }
 
+impl<'a, 'tcx> IncrementVisitor<'a, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>) -> Self {
+        Self {
+            cx,
+            states: FxHashMap::default(),
+            depth: 0,
+            done: false,
+        }
+    }
+
+    fn into_results(self) -> impl Iterator<Item = HirId> {
+        self.states.into_iter().filter_map(|(id, state)| {
+            if state == IncrementVisitorVarState::IncrOnce {
+                Some(id)
+            } else {
+                None
+            }
+        })
+    }
+}
+
 impl<'a, 'tcx> Visitor<'tcx> for IncrementVisitor<'a, 'tcx> {
     type Map = Map<'tcx>;
 
@@ -2158,85 +2355,118 @@ impl<'a, 'tcx> Visitor<'tcx> for IncrementVisitor<'a, 'tcx> {
         // If node is a variable
         if let Some(def_id) = var_def_id(self.cx, expr) {
             if let Some(parent) = get_parent_expr(self.cx, expr) {
-                let state = self.states.entry(def_id).or_insert(VarState::Initial);
-                if *state == VarState::IncrOnce {
-                    *state = VarState::DontWarn;
+                let state = self.states.entry(def_id).or_insert(IncrementVisitorVarState::Initial);
+                if *state == IncrementVisitorVarState::IncrOnce {
+                    *state = IncrementVisitorVarState::DontWarn;
                     return;
                 }
 
                 match parent.kind {
                     ExprKind::AssignOp(op, ref lhs, ref rhs) => {
                         if lhs.hir_id == expr.hir_id {
-                            if op.node == BinOpKind::Add && is_integer_const(self.cx, rhs, 1) {
-                                *state = match *state {
-                                    VarState::Initial if self.depth == 0 => VarState::IncrOnce,
-                                    _ => VarState::DontWarn,
-                                };
+                            *state = if op.node == BinOpKind::Add
+                                && is_integer_const(self.cx, rhs, 1)
+                                && *state == IncrementVisitorVarState::Initial
+                                && self.depth == 0
+                            {
+                                IncrementVisitorVarState::IncrOnce
                             } else {
-                                // Assigned some other value
-                                *state = VarState::DontWarn;
-                            }
+                                // Assigned some other value or assigned multiple times
+                                IncrementVisitorVarState::DontWarn
+                            };
                         }
                     },
-                    ExprKind::Assign(ref lhs, _, _) if lhs.hir_id == expr.hir_id => *state = VarState::DontWarn,
+                    ExprKind::Assign(ref lhs, _, _) if lhs.hir_id == expr.hir_id => {
+                        *state = IncrementVisitorVarState::DontWarn
+                    },
                     ExprKind::AddrOf(BorrowKind::Ref, mutability, _) if mutability == Mutability::Mut => {
-                        *state = VarState::DontWarn
+                        *state = IncrementVisitorVarState::DontWarn
                     },
                     _ => (),
                 }
             }
+
+            walk_expr(self, expr);
         } else if is_loop(expr) || is_conditional(expr) {
             self.depth += 1;
             walk_expr(self, expr);
             self.depth -= 1;
-            return;
         } else if let ExprKind::Continue(_) = expr.kind {
             self.done = true;
-            return;
+        } else {
+            walk_expr(self, expr);
         }
-        walk_expr(self, expr);
     }
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
     }
 }
 
-/// Checks whether a variable is initialized to zero at the start of a loop.
+enum InitializeVisitorState<'hir> {
+    Initial,          // Not examined yet
+    Declared(Symbol), // Declared but not (yet) initialized
+    Initialized {
+        name: Symbol,
+        initializer: &'hir Expr<'hir>,
+    },
+    DontWarn,
+}
+
+/// Checks whether a variable is initialized at the start of a loop and not modified
+/// and used after the loop.
 struct InitializeVisitor<'a, 'tcx> {
     cx: &'a LateContext<'tcx>,  // context reference
     end_expr: &'tcx Expr<'tcx>, // the for loop. Stop scanning here.
     var_id: HirId,
-    state: VarState,
-    name: Option<Symbol>,
+    state: InitializeVisitorState<'tcx>,
     depth: u32, // depth of conditional expressions
     past_loop: bool,
 }
 
+impl<'a, 'tcx> InitializeVisitor<'a, 'tcx> {
+    fn new(cx: &'a LateContext<'tcx>, end_expr: &'tcx Expr<'tcx>, var_id: HirId) -> Self {
+        Self {
+            cx,
+            end_expr,
+            var_id,
+            state: InitializeVisitorState::Initial,
+            depth: 0,
+            past_loop: false,
+        }
+    }
+
+    fn get_result(&self) -> Option<(Symbol, &'tcx Expr<'tcx>)> {
+        if let InitializeVisitorState::Initialized { name, initializer } = self.state {
+            Some((name, initializer))
+        } else {
+            None
+        }
+    }
+}
+
 impl<'a, 'tcx> Visitor<'tcx> for InitializeVisitor<'a, 'tcx> {
     type Map = Map<'tcx>;
 
     fn visit_stmt(&mut self, stmt: &'tcx Stmt<'_>) {
         // Look for declarations of the variable
-        if let StmtKind::Local(ref local) = stmt.kind {
-            if local.pat.hir_id == self.var_id {
-                if let PatKind::Binding(.., ident, _) = local.pat.kind {
-                    self.name = Some(ident.name);
-
-                    self.state = local.init.as_ref().map_or(VarState::Declared, |init| {
-                        if is_integer_const(&self.cx, init, 0) {
-                            VarState::Warn
-                        } else {
-                            VarState::Declared
-                        }
-                    })
-                }
+        if_chain! {
+            if let StmtKind::Local(ref local) = stmt.kind;
+            if local.pat.hir_id == self.var_id;
+            if let PatKind::Binding(.., ident, _) = local.pat.kind;
+            then {
+                self.state = local.init.map_or(InitializeVisitorState::Declared(ident.name), |init| {
+                    InitializeVisitorState::Initialized {
+                        initializer: init,
+                        name: ident.name,
+                    }
+                })
             }
         }
         walk_stmt(self, stmt);
     }
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
-        if self.state == VarState::DontWarn {
+        if matches!(self.state, InitializeVisitorState::DontWarn) {
             return;
         }
         if expr.hir_id == self.end_expr.hir_id {
@@ -2245,45 +2475,51 @@ impl<'a, 'tcx> Visitor<'tcx> for InitializeVisitor<'a, 'tcx> {
         }
         // No need to visit expressions before the variable is
         // declared
-        if self.state == VarState::IncrOnce {
+        if matches!(self.state, InitializeVisitorState::Initial) {
             return;
         }
 
         // If node is the desired variable, see how it's used
         if var_def_id(self.cx, expr) == Some(self.var_id) {
+            if self.past_loop {
+                self.state = InitializeVisitorState::DontWarn;
+                return;
+            }
+
             if let Some(parent) = get_parent_expr(self.cx, expr) {
                 match parent.kind {
                     ExprKind::AssignOp(_, ref lhs, _) if lhs.hir_id == expr.hir_id => {
-                        self.state = VarState::DontWarn;
+                        self.state = InitializeVisitorState::DontWarn;
                     },
                     ExprKind::Assign(ref lhs, ref rhs, _) if lhs.hir_id == expr.hir_id => {
-                        self.state = if is_integer_const(&self.cx, rhs, 0) && self.depth == 0 {
-                            VarState::Warn
-                        } else {
-                            VarState::DontWarn
+                        self.state = if_chain! {
+                            if self.depth == 0;
+                            if let InitializeVisitorState::Declared(name)
+                                | InitializeVisitorState::Initialized { name, ..} = self.state;
+                            then {
+                                InitializeVisitorState::Initialized { initializer: rhs, name }
+                            } else {
+                                InitializeVisitorState::DontWarn
+                            }
                         }
                     },
                     ExprKind::AddrOf(BorrowKind::Ref, mutability, _) if mutability == Mutability::Mut => {
-                        self.state = VarState::DontWarn
+                        self.state = InitializeVisitorState::DontWarn
                     },
                     _ => (),
                 }
             }
 
-            if self.past_loop {
-                self.state = VarState::DontWarn;
-                return;
-            }
+            walk_expr(self, expr);
         } else if !self.past_loop && is_loop(expr) {
-            self.state = VarState::DontWarn;
-            return;
+            self.state = InitializeVisitorState::DontWarn;
         } else if is_conditional(expr) {
             self.depth += 1;
             walk_expr(self, expr);
             self.depth -= 1;
-            return;
+        } else {
+            walk_expr(self, expr);
         }
-        walk_expr(self, expr);
     }
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
diff --git a/clippy_lints/src/manual_unwrap_or.rs b/clippy_lints/src/manual_unwrap_or.rs
new file mode 100644
index 00000000000..ddb8cc25077
--- /dev/null
+++ b/clippy_lints/src/manual_unwrap_or.rs
@@ -0,0 +1,104 @@
+use crate::consts::constant_simple;
+use crate::utils;
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{def, Arm, Expr, ExprKind, PatKind, QPath};
+use rustc_lint::LintContext;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::lint::in_external_macro;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:**
+    /// Finds patterns that reimplement `Option::unwrap_or`.
+    ///
+    /// **Why is this bad?**
+    /// Concise code helps focusing on behavior instead of boilerplate.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// let foo: Option<i32> = None;
+    /// match foo {
+    ///     Some(v) => v,
+    ///     None => 1,
+    /// };
+    /// ```
+    ///
+    /// Use instead:
+    /// ```rust
+    /// let foo: Option<i32> = None;
+    /// foo.unwrap_or(1);
+    /// ```
+    pub MANUAL_UNWRAP_OR,
+    complexity,
+    "finds patterns that can be encoded more concisely with `Option::unwrap_or`"
+}
+
+declare_lint_pass!(ManualUnwrapOr => [MANUAL_UNWRAP_OR]);
+
+impl LateLintPass<'_> for ManualUnwrapOr {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
+        if in_external_macro(cx.sess(), expr.span) {
+            return;
+        }
+        lint_option_unwrap_or_case(cx, expr);
+    }
+}
+
+fn lint_option_unwrap_or_case<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
+    fn applicable_none_arm<'a>(arms: &'a [Arm<'a>]) -> Option<&'a Arm<'a>> {
+        if_chain! {
+            if arms.len() == 2;
+            if arms.iter().all(|arm| arm.guard.is_none());
+            if let Some((idx, none_arm)) = arms.iter().enumerate().find(|(_, arm)|
+                if let PatKind::Path(ref qpath) = arm.pat.kind {
+                    utils::match_qpath(qpath, &utils::paths::OPTION_NONE)
+                } else {
+                    false
+                }
+            );
+            let some_arm = &arms[1 - idx];
+            if let PatKind::TupleStruct(ref some_qpath, &[some_binding], _) = some_arm.pat.kind;
+            if utils::match_qpath(some_qpath, &utils::paths::OPTION_SOME);
+            if let PatKind::Binding(_, binding_hir_id, ..) = some_binding.kind;
+            if let ExprKind::Path(QPath::Resolved(_, body_path)) = some_arm.body.kind;
+            if let def::Res::Local(body_path_hir_id) = body_path.res;
+            if body_path_hir_id == binding_hir_id;
+            if !utils::usage::contains_return_break_continue_macro(none_arm.body);
+            then {
+                Some(none_arm)
+            } else {
+                None
+            }
+        }
+    }
+
+    if_chain! {
+        if let ExprKind::Match(scrutinee, match_arms, _) = expr.kind;
+        let ty = cx.typeck_results().expr_ty(scrutinee);
+        if utils::is_type_diagnostic_item(cx, ty, sym!(option_type));
+        if let Some(none_arm) = applicable_none_arm(match_arms);
+        if let Some(scrutinee_snippet) = utils::snippet_opt(cx, scrutinee.span);
+        if let Some(none_body_snippet) = utils::snippet_opt(cx, none_arm.body.span);
+        if let Some(indent) = utils::indent_of(cx, expr.span);
+        if constant_simple(cx, cx.typeck_results(), none_arm.body).is_some();
+        then {
+            let reindented_none_body =
+                utils::reindent_multiline(none_body_snippet.into(), true, Some(indent));
+            utils::span_lint_and_sugg(
+                cx,
+                MANUAL_UNWRAP_OR, expr.span,
+                "this pattern reimplements `Option::unwrap_or`",
+                "replace with",
+                format!(
+                    "{}.unwrap_or({})",
+                    scrutinee_snippet,
+                    reindented_none_body,
+                ),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+}
diff --git a/clippy_lints/src/mut_key.rs b/clippy_lints/src/mut_key.rs
index 8a2dbdc50ea..4525b12689f 100644
--- a/clippy_lints/src/mut_key.rs
+++ b/clippy_lints/src/mut_key.rs
@@ -1,6 +1,7 @@
 use crate::utils::{match_def_path, paths, span_lint, trait_ref_of_method};
 use rustc_hir as hir;
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{Adt, Array, RawPtr, Ref, Slice, Tuple, Ty, TypeAndMut};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
@@ -120,7 +121,11 @@ fn is_mutable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span) -> bo
             size.try_eval_usize(cx.tcx, cx.param_env).map_or(true, |u| u != 0) && is_mutable_type(cx, inner_ty, span)
         },
         Tuple(..) => ty.tuple_fields().any(|ty| is_mutable_type(cx, ty, span)),
-        Adt(..) => cx.tcx.layout_of(cx.param_env.and(ty)).is_ok() && !ty.is_freeze(cx.tcx.at(span), cx.param_env),
+        Adt(..) => {
+            cx.tcx.layout_of(cx.param_env.and(ty)).is_ok()
+                && !ty.has_escaping_bound_vars()
+                && !ty.is_freeze(cx.tcx.at(span), cx.param_env)
+        },
         _ => false,
     }
 }
diff --git a/clippy_lints/src/mutable_debug_assertion.rs b/clippy_lints/src/mutable_debug_assertion.rs
index cc635c2a202..76417aa7ed0 100644
--- a/clippy_lints/src/mutable_debug_assertion.rs
+++ b/clippy_lints/src/mutable_debug_assertion.rs
@@ -1,7 +1,6 @@
-use crate::utils::{is_direct_expn_of, span_lint};
-use if_chain::if_chain;
+use crate::utils::{higher, is_direct_expn_of, span_lint};
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::{BorrowKind, Expr, ExprKind, MatchSource, Mutability, StmtKind, UnOp};
+use rustc_hir::{BorrowKind, Expr, ExprKind, MatchSource, Mutability};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_middle::ty;
@@ -39,66 +38,23 @@ impl<'tcx> LateLintPass<'tcx> for DebugAssertWithMutCall {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
         for dmn in &DEBUG_MACRO_NAMES {
             if is_direct_expn_of(e.span, dmn).is_some() {
-                if let Some(span) = extract_call(cx, e) {
-                    span_lint(
-                        cx,
-                        DEBUG_ASSERT_WITH_MUT_CALL,
-                        span,
-                        &format!("do not call a function with mutable arguments inside of `{}!`", dmn),
-                    );
-                }
-            }
-        }
-    }
-}
-
-//HACK(hellow554): remove this when #4694 is implemented
-fn extract_call<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<Span> {
-    if_chain! {
-        if let ExprKind::Block(ref block, _) = e.kind;
-        if block.stmts.len() == 1;
-        if let StmtKind::Semi(ref matchexpr) = block.stmts[0].kind;
-        then {
-            // debug_assert
-            if_chain! {
-                if let ExprKind::Match(ref ifclause, _, _) = matchexpr.kind;
-                if let ExprKind::DropTemps(ref droptmp) = ifclause.kind;
-                if let ExprKind::Unary(UnOp::UnNot, ref condition) = droptmp.kind;
-                then {
-                    let mut visitor = MutArgVisitor::new(cx);
-                    visitor.visit_expr(condition);
-                    return visitor.expr_span();
-                }
-            }
-
-            // debug_assert_{eq,ne}
-            if_chain! {
-                if let ExprKind::Block(ref matchblock, _) = matchexpr.kind;
-                if let Some(ref matchheader) = matchblock.expr;
-                if let ExprKind::Match(ref headerexpr, _, _) = matchheader.kind;
-                if let ExprKind::Tup(ref conditions) = headerexpr.kind;
-                if conditions.len() == 2;
-                then {
-                    if let ExprKind::AddrOf(BorrowKind::Ref, _, ref lhs) = conditions[0].kind {
+                if let Some(macro_args) = higher::extract_assert_macro_args(e) {
+                    for arg in macro_args {
                         let mut visitor = MutArgVisitor::new(cx);
-                        visitor.visit_expr(lhs);
+                        visitor.visit_expr(arg);
                         if let Some(span) = visitor.expr_span() {
-                            return Some(span);
-                        }
-                    }
-                    if let ExprKind::AddrOf(BorrowKind::Ref, _, ref rhs) = conditions[1].kind {
-                        let mut visitor = MutArgVisitor::new(cx);
-                        visitor.visit_expr(rhs);
-                        if let Some(span) = visitor.expr_span() {
-                            return Some(span);
+                            span_lint(
+                                cx,
+                                DEBUG_ASSERT_WITH_MUT_CALL,
+                                span,
+                                &format!("do not call a function with mutable arguments inside of `{}!`", dmn),
+                            );
                         }
                     }
                 }
             }
         }
     }
-
-    None
 }
 
 struct MutArgVisitor<'a, 'tcx> {
diff --git a/clippy_lints/src/option_if_let_else.rs b/clippy_lints/src/option_if_let_else.rs
index 4a3eb9c983a..eb7624b25a3 100644
--- a/clippy_lints/src/option_if_let_else.rs
+++ b/clippy_lints/src/option_if_let_else.rs
@@ -5,22 +5,20 @@ use crate::utils::{is_type_diagnostic_item, paths, span_lint_and_sugg};
 use if_chain::if_chain;
 
 use rustc_errors::Applicability;
-use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
 use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, PatKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::hir::map::Map;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 declare_clippy_lint! {
     /// **What it does:**
-    /// Lints usage of  `if let Some(v) = ... { y } else { x }` which is more
+    /// Lints usage of `if let Some(v) = ... { y } else { x }` which is more
     /// idiomatically done with `Option::map_or` (if the else bit is a pure
     /// expression) or `Option::map_or_else` (if the else bit is an impure
-    /// expresion).
+    /// expression).
     ///
     /// **Why is this bad?**
     /// Using the dedicated functions of the Option type is clearer and
-    /// more concise than an if let expression.
+    /// more concise than an `if let` expression.
     ///
     /// **Known problems:**
     /// This lint uses a deliberately conservative metric for checking
@@ -84,53 +82,6 @@ struct OptionIfLetElseOccurence {
     wrap_braces: bool,
 }
 
-struct ReturnBreakContinueMacroVisitor {
-    seen_return_break_continue: bool,
-}
-
-impl ReturnBreakContinueMacroVisitor {
-    fn new() -> ReturnBreakContinueMacroVisitor {
-        ReturnBreakContinueMacroVisitor {
-            seen_return_break_continue: false,
-        }
-    }
-}
-
-impl<'tcx> Visitor<'tcx> for ReturnBreakContinueMacroVisitor {
-    type Map = Map<'tcx>;
-    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
-        NestedVisitorMap::None
-    }
-
-    fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
-        if self.seen_return_break_continue {
-            // No need to look farther if we've already seen one of them
-            return;
-        }
-        match &ex.kind {
-            ExprKind::Ret(..) | ExprKind::Break(..) | ExprKind::Continue(..) => {
-                self.seen_return_break_continue = true;
-            },
-            // Something special could be done here to handle while or for loop
-            // desugaring, as this will detect a break if there's a while loop
-            // or a for loop inside the expression.
-            _ => {
-                if utils::in_macro(ex.span) {
-                    self.seen_return_break_continue = true;
-                } else {
-                    rustc_hir::intravisit::walk_expr(self, ex);
-                }
-            },
-        }
-    }
-}
-
-fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
-    let mut recursive_visitor = ReturnBreakContinueMacroVisitor::new();
-    recursive_visitor.visit_expr(expression);
-    recursive_visitor.seen_return_break_continue
-}
-
 /// Extracts the body of a given arm. If the arm contains only an expression,
 /// then it returns the expression. Otherwise, it returns the entire block
 fn extract_body_from_arm<'a>(arm: &'a Arm<'a>) -> Option<&'a Expr<'a>> {
@@ -208,8 +159,8 @@ fn detect_option_if_let_else<'tcx>(
         if let PatKind::TupleStruct(struct_qpath, &[inner_pat], _) = &arms[0].pat.kind;
         if utils::match_qpath(struct_qpath, &paths::OPTION_SOME);
         if let PatKind::Binding(bind_annotation, _, id, _) = &inner_pat.kind;
-        if !contains_return_break_continue_macro(arms[0].body);
-        if !contains_return_break_continue_macro(arms[1].body);
+        if !utils::usage::contains_return_break_continue_macro(arms[0].body);
+        if !utils::usage::contains_return_break_continue_macro(arms[1].body);
         then {
             let capture_mut = if bind_annotation == &BindingAnnotation::Mutable { "mut " } else { "" };
             let some_body = extract_body_from_arm(&arms[0])?;
diff --git a/clippy_lints/src/ptr_eq.rs b/clippy_lints/src/ptr_eq.rs
new file mode 100644
index 00000000000..3be792ce5e4
--- /dev/null
+++ b/clippy_lints/src/ptr_eq.rs
@@ -0,0 +1,96 @@
+use crate::utils;
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// **What it does:** Use `std::ptr::eq` when applicable
+    ///
+    /// **Why is this bad?** `ptr::eq` can be used to compare `&T` references
+    /// (which coerce to `*const T` implicitly) by their address rather than
+    /// comparing the values they point to.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// let a = &[1, 2, 3];
+    /// let b = &[1, 2, 3];
+    ///
+    /// assert!(a as *const _ as usize == b as *const _ as usize);
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let a = &[1, 2, 3];
+    /// let b = &[1, 2, 3];
+    ///
+    /// assert!(std::ptr::eq(a, b));
+    /// ```
+    pub PTR_EQ,
+    style,
+    "use `std::ptr::eq` when comparing raw pointers"
+}
+
+declare_lint_pass!(PtrEq => [PTR_EQ]);
+
+static LINT_MSG: &str = "use `std::ptr::eq` when comparing raw pointers";
+
+impl LateLintPass<'_> for PtrEq {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        if utils::in_macro(expr.span) {
+            return;
+        }
+
+        if let ExprKind::Binary(ref op, ref left, ref right) = expr.kind {
+            if BinOpKind::Eq == op.node {
+                let (left, right) = match (expr_as_cast_to_usize(cx, left), expr_as_cast_to_usize(cx, right)) {
+                    (Some(lhs), Some(rhs)) => (lhs, rhs),
+                    _ => (&**left, &**right),
+                };
+
+                if_chain! {
+                    if let Some(left_var) = expr_as_cast_to_raw_pointer(cx, left);
+                    if let Some(right_var) = expr_as_cast_to_raw_pointer(cx, right);
+                    if let Some(left_snip) = utils::snippet_opt(cx, left_var.span);
+                    if let Some(right_snip) = utils::snippet_opt(cx, right_var.span);
+                    then {
+                        utils::span_lint_and_sugg(
+                            cx,
+                            PTR_EQ,
+                            expr.span,
+                            LINT_MSG,
+                            "try",
+                            format!("std::ptr::eq({}, {})", left_snip, right_snip),
+                            Applicability::MachineApplicable,
+                            );
+                    }
+                }
+            }
+        }
+    }
+}
+
+// If the given expression is a cast to an usize, return the lhs of the cast
+// E.g., `foo as *const _ as usize` returns `foo as *const _`.
+fn expr_as_cast_to_usize<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
+    if cx.typeck_results().expr_ty(cast_expr) == cx.tcx.types.usize {
+        if let ExprKind::Cast(ref expr, _) = cast_expr.kind {
+            return Some(expr);
+        }
+    }
+    None
+}
+
+// If the given expression is a cast to a `*const` pointer, return the lhs of the cast
+// E.g., `foo as *const _` returns `foo`.
+fn expr_as_cast_to_raw_pointer<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
+    if cx.typeck_results().expr_ty(cast_expr).is_unsafe_ptr() {
+        if let ExprKind::Cast(ref expr, _) = cast_expr.kind {
+            return Some(expr);
+        }
+    }
+    None
+}
diff --git a/clippy_lints/src/transmute.rs b/clippy_lints/src/transmute.rs
index c75adb62f25..47c650ac27d 100644
--- a/clippy_lints/src/transmute.rs
+++ b/clippy_lints/src/transmute.rs
@@ -98,7 +98,11 @@ declare_clippy_lint! {
     ///
     /// **Why is this bad?** This can always be rewritten with `&` and `*`.
     ///
-    /// **Known problems:** None.
+    /// **Known problems:**
+    /// - `mem::transmute` in statics and constants is stable from Rust 1.46.0,
+    /// while dereferencing raw pointer is not stable yet.
+    /// If you need to do this in those places,
+    /// you would have to use `transmute` instead.
     ///
     /// **Example:**
     /// ```rust,ignore
diff --git a/clippy_lints/src/trivially_copy_pass_by_ref.rs b/clippy_lints/src/trivially_copy_pass_by_ref.rs
index d92eb86fb2e..c2c86aa474a 100644
--- a/clippy_lints/src/trivially_copy_pass_by_ref.rs
+++ b/clippy_lints/src/trivially_copy_pass_by_ref.rs
@@ -14,6 +14,7 @@ use rustc_span::Span;
 use rustc_target::abi::LayoutOf;
 use rustc_target::spec::Target;
 use rustc_target::spec::abi::Abi;
+use rustc_target::spec::Target;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for functions taking arguments by reference, where
diff --git a/clippy_lints/src/types.rs b/clippy_lints/src/types.rs
index 5e83b6c81ec..9a948af8bfc 100644
--- a/clippy_lints/src/types.rs
+++ b/clippy_lints/src/types.rs
@@ -17,6 +17,7 @@ use rustc_hir::{
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, InferTy, Ty, TyCtxt, TyS, TypeckResults};
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -541,6 +542,7 @@ impl Types {
                                 _ => None,
                             });
                             let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty);
+                            if !ty_ty.has_escaping_bound_vars();
                             if ty_ty.is_sized(cx.tcx.at(ty.span), cx.param_env);
                             if let Ok(ty_ty_size) = cx.layout_of(ty_ty).map(|l| l.size.bytes());
                             if ty_ty_size <= self.vec_box_size_threshold;
diff --git a/clippy_lints/src/utils/eager_or_lazy.rs b/clippy_lints/src/utils/eager_or_lazy.rs
index 27e9567740d..4ceea13df37 100644
--- a/clippy_lints/src/utils/eager_or_lazy.rs
+++ b/clippy_lints/src/utils/eager_or_lazy.rs
@@ -82,7 +82,7 @@ fn identify_some_pure_patterns(expr: &Expr<'_>) -> bool {
 /// Identify some potentially computationally expensive patterns.
 /// This function is named so to stress that its implementation is non-exhaustive.
 /// It returns FNs and FPs.
-fn identify_some_potentially_expensive_patterns<'a, 'tcx>(cx: &'a LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
+fn identify_some_potentially_expensive_patterns<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
     // Searches an expression for method calls or function calls that aren't ctors
     struct FunCallFinder<'a, 'tcx> {
         cx: &'a LateContext<'tcx>,
diff --git a/clippy_lints/src/utils/higher.rs b/clippy_lints/src/utils/higher.rs
index 8563b469a30..6d7c5058b4f 100644
--- a/clippy_lints/src/utils/higher.rs
+++ b/clippy_lints/src/utils/higher.rs
@@ -7,6 +7,7 @@ use crate::utils::{is_expn_of, match_def_path, paths};
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_hir as hir;
+use rustc_hir::{BorrowKind, Expr, ExprKind, StmtKind, UnOp};
 use rustc_lint::LateContext;
 
 /// Converts a hir binary operator to the corresponding `ast` type.
@@ -241,3 +242,56 @@ pub fn vec_macro<'e>(cx: &LateContext<'_>, expr: &'e hir::Expr<'_>) -> Option<Ve
 
     None
 }
+
+/// Extract args from an assert-like macro.
+/// Currently working with:
+/// - `assert!`, `assert_eq!` and `assert_ne!`
+/// - `debug_assert!`, `debug_assert_eq!` and `debug_assert_ne!`
+/// For example:
+/// `assert!(expr)` will return Some([expr])
+/// `debug_assert_eq!(a, b)` will return Some([a, b])
+pub fn extract_assert_macro_args<'tcx>(e: &'tcx Expr<'tcx>) -> Option<Vec<&'tcx Expr<'tcx>>> {
+    /// Try to match the AST for a pattern that contains a match, for example when two args are
+    /// compared
+    fn ast_matchblock(matchblock_expr: &'tcx Expr<'tcx>) -> Option<Vec<&Expr<'_>>> {
+        if_chain! {
+            if let ExprKind::Match(ref headerexpr, _, _) = &matchblock_expr.kind;
+            if let ExprKind::Tup([lhs, rhs]) = &headerexpr.kind;
+            if let ExprKind::AddrOf(BorrowKind::Ref, _, lhs) = lhs.kind;
+            if let ExprKind::AddrOf(BorrowKind::Ref, _, rhs) = rhs.kind;
+            then {
+                return Some(vec![lhs, rhs]);
+            }
+        }
+        None
+    }
+
+    if let ExprKind::Block(ref block, _) = e.kind {
+        if block.stmts.len() == 1 {
+            if let StmtKind::Semi(ref matchexpr) = block.stmts[0].kind {
+                // macros with unique arg: `{debug_}assert!` (e.g., `debug_assert!(some_condition)`)
+                if_chain! {
+                    if let ExprKind::Match(ref ifclause, _, _) = matchexpr.kind;
+                    if let ExprKind::DropTemps(ref droptmp) = ifclause.kind;
+                    if let ExprKind::Unary(UnOp::UnNot, condition) = droptmp.kind;
+                    then {
+                        return Some(vec![condition]);
+                    }
+                }
+
+                // debug macros with two args: `debug_assert_{ne, eq}` (e.g., `assert_ne!(a, b)`)
+                if_chain! {
+                    if let ExprKind::Block(ref matchblock,_) = matchexpr.kind;
+                    if let Some(ref matchblock_expr) = matchblock.expr;
+                    then {
+                        return ast_matchblock(matchblock_expr);
+                    }
+                }
+            }
+        } else if let Some(matchblock_expr) = block.expr {
+            // macros with two args: `assert_{ne, eq}` (e.g., `assert_ne!(a, b)`)
+            return ast_matchblock(&matchblock_expr);
+        }
+    }
+    None
+}
diff --git a/clippy_lints/src/utils/mod.rs b/clippy_lints/src/utils/mod.rs
index 790ac4f7dd8..a9d26d48b12 100644
--- a/clippy_lints/src/utils/mod.rs
+++ b/clippy_lints/src/utils/mod.rs
@@ -708,7 +708,7 @@ fn reindent_multiline_inner(s: &str, ignore_first: bool, indent: Option<usize>,
 }
 
 /// Gets the parent expression, if any –- this is useful to constrain a lint.
-pub fn get_parent_expr<'c>(cx: &'c LateContext<'_>, e: &Expr<'_>) -> Option<&'c Expr<'c>> {
+pub fn get_parent_expr<'tcx>(cx: &LateContext<'tcx>, e: &Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
     let map = &cx.tcx.hir();
     let hir_id = e.hir_id;
     let parent_id = map.get_parent_node(hir_id);
diff --git a/clippy_lints/src/utils/sugg.rs b/clippy_lints/src/utils/sugg.rs
index a2a1d109c9a..625120b880e 100644
--- a/clippy_lints/src/utils/sugg.rs
+++ b/clippy_lints/src/utils/sugg.rs
@@ -13,8 +13,10 @@ use rustc_span::{BytePos, Pos};
 use std::borrow::Cow;
 use std::convert::TryInto;
 use std::fmt::Display;
+use std::ops::{Add, Neg, Not, Sub};
 
 /// A helper type to build suggestion correctly handling parenthesis.
+#[derive(Clone, PartialEq)]
 pub enum Sugg<'a> {
     /// An expression that never needs parenthesis such as `1337` or `[0; 42]`.
     NonParen(Cow<'a, str>),
@@ -25,8 +27,12 @@ pub enum Sugg<'a> {
     BinOp(AssocOp, Cow<'a, str>),
 }
 
+/// Literal constant `0`, for convenience.
+pub const ZERO: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("0"));
 /// Literal constant `1`, for convenience.
 pub const ONE: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("1"));
+/// a constant represents an empty string, for convenience.
+pub const EMPTY: Sugg<'static> = Sugg::NonParen(Cow::Borrowed(""));
 
 impl Display for Sugg<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
@@ -269,21 +275,60 @@ impl<'a> Sugg<'a> {
     }
 }
 
-impl<'a, 'b> std::ops::Add<Sugg<'b>> for Sugg<'a> {
+// Copied from the rust standart library, and then edited
+macro_rules! forward_binop_impls_to_ref {
+    (impl $imp:ident, $method:ident for $t:ty, type Output = $o:ty) => {
+        impl $imp<$t> for &$t {
+            type Output = $o;
+
+            fn $method(self, other: $t) -> $o {
+                $imp::$method(self, &other)
+            }
+        }
+
+        impl $imp<&$t> for $t {
+            type Output = $o;
+
+            fn $method(self, other: &$t) -> $o {
+                $imp::$method(&self, other)
+            }
+        }
+
+        impl $imp for $t {
+            type Output = $o;
+
+            fn $method(self, other: $t) -> $o {
+                $imp::$method(&self, &other)
+            }
+        }
+    };
+}
+
+impl Add for &Sugg<'_> {
     type Output = Sugg<'static>;
-    fn add(self, rhs: Sugg<'b>) -> Sugg<'static> {
-        make_binop(ast::BinOpKind::Add, &self, &rhs)
+    fn add(self, rhs: &Sugg<'_>) -> Sugg<'static> {
+        make_binop(ast::BinOpKind::Add, self, rhs)
     }
 }
 
-impl<'a, 'b> std::ops::Sub<Sugg<'b>> for Sugg<'a> {
+impl Sub for &Sugg<'_> {
+    type Output = Sugg<'static>;
+    fn sub(self, rhs: &Sugg<'_>) -> Sugg<'static> {
+        make_binop(ast::BinOpKind::Sub, self, rhs)
+    }
+}
+
+forward_binop_impls_to_ref!(impl Add, add for Sugg<'_>, type Output = Sugg<'static>);
+forward_binop_impls_to_ref!(impl Sub, sub for Sugg<'_>, type Output = Sugg<'static>);
+
+impl Neg for Sugg<'_> {
     type Output = Sugg<'static>;
-    fn sub(self, rhs: Sugg<'b>) -> Sugg<'static> {
-        make_binop(ast::BinOpKind::Sub, &self, &rhs)
+    fn neg(self) -> Sugg<'static> {
+        make_unop("-", self)
     }
 }
 
-impl<'a> std::ops::Not for Sugg<'a> {
+impl Not for Sugg<'_> {
     type Output = Sugg<'static>;
     fn not(self) -> Sugg<'static> {
         make_unop("!", self)
diff --git a/clippy_lints/src/utils/usage.rs b/clippy_lints/src/utils/usage.rs
index ea1dc3be29b..2fd6046ebcf 100644
--- a/clippy_lints/src/utils/usage.rs
+++ b/clippy_lints/src/utils/usage.rs
@@ -1,10 +1,11 @@
+use crate::utils;
 use crate::utils::match_var;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::intravisit;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::{Expr, HirId, Path};
+use rustc_hir::{Expr, ExprKind, HirId, Path};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
@@ -174,3 +175,50 @@ impl<'a, 'tcx> intravisit::Visitor<'tcx> for BindingUsageFinder<'a, 'tcx> {
         intravisit::NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
     }
 }
+
+struct ReturnBreakContinueMacroVisitor {
+    seen_return_break_continue: bool,
+}
+
+impl ReturnBreakContinueMacroVisitor {
+    fn new() -> ReturnBreakContinueMacroVisitor {
+        ReturnBreakContinueMacroVisitor {
+            seen_return_break_continue: false,
+        }
+    }
+}
+
+impl<'tcx> Visitor<'tcx> for ReturnBreakContinueMacroVisitor {
+    type Map = Map<'tcx>;
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+        NestedVisitorMap::None
+    }
+
+    fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) {
+        if self.seen_return_break_continue {
+            // No need to look farther if we've already seen one of them
+            return;
+        }
+        match &ex.kind {
+            ExprKind::Ret(..) | ExprKind::Break(..) | ExprKind::Continue(..) => {
+                self.seen_return_break_continue = true;
+            },
+            // Something special could be done here to handle while or for loop
+            // desugaring, as this will detect a break if there's a while loop
+            // or a for loop inside the expression.
+            _ => {
+                if utils::in_macro(ex.span) {
+                    self.seen_return_break_continue = true;
+                } else {
+                    rustc_hir::intravisit::walk_expr(self, ex);
+                }
+            },
+        }
+    }
+}
+
+pub fn contains_return_break_continue_macro(expression: &Expr<'_>) -> bool {
+    let mut recursive_visitor = ReturnBreakContinueMacroVisitor::new();
+    recursive_visitor.visit_expr(expression);
+    recursive_visitor.seen_return_break_continue
+}
diff --git a/doc/adding_lints.md b/doc/adding_lints.md
index 2869c3bf7d4..2572833b8de 100644
--- a/doc/adding_lints.md
+++ b/doc/adding_lints.md
@@ -104,7 +104,8 @@ every time before running `tests/ui/update-all-references.sh`.
 Running `TESTNAME=foo_functions cargo uitest` should pass then. When we commit
 our lint, we need to commit the generated `.stderr` files, too. In general, you
 should only commit files changed by `tests/ui/update-all-references.sh` for the
-specific lint you are creating/editing.
+specific lint you are creating/editing. Note that if the generated files are
+empty, they should be removed.
 
 ### Cargo lints
 
@@ -224,6 +225,17 @@ automate everything. We will have to register our lint pass manually in the
 store.register_early_pass(|| box foo_functions::FooFunctions);
 ```
 
+As one may expect, there is a corresponding `register_late_pass` method
+available as well. Without a call to one of `register_early_pass` or 
+`register_late_pass`, the lint pass in question will not be run.
+
+One reason that `cargo dev` does not automate this step is that multiple lints 
+can use the same lint pass, so registering the lint pass may already be done
+when adding a new lint. Another reason that this step is not automated is that
+the order that the passes are registered determines the order the passes 
+actually run, which in turn affects the order that any emitted lints are output
+in.
+
 [declare_clippy_lint]: https://github.com/rust-lang/rust-clippy/blob/557f6848bd5b7183f55c1e1522a326e9e1df6030/clippy_lints/src/lib.rs#L60
 [example_lint_page]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
 [lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
@@ -453,12 +465,12 @@ Before submitting your PR make sure you followed all of the basic requirements:
 
 <!-- Sync this with `.github/PULL_REQUEST_TEMPLATE` -->
 
-- [ ] Followed [lint naming conventions][lint_naming]
-- [ ] Added passing UI tests (including committed `.stderr` file)
-- [ ] `cargo test` passes locally
-- [ ] Executed `cargo dev update_lints`
-- [ ] Added lint documentation
-- [ ] Run `cargo dev fmt`
+- \[ ] Followed [lint naming conventions][lint_naming]
+- \[ ] Added passing UI tests (including committed `.stderr` file)
+- \[ ] `cargo test` passes locally
+- \[ ] Executed `cargo dev update_lints`
+- \[ ] Added lint documentation
+- \[ ] Run `cargo dev fmt`
 
 ## Cheatsheet
 
diff --git a/doc/backport.md b/doc/backport.md
index 259696658ea..15f3d1f0806 100644
--- a/doc/backport.md
+++ b/doc/backport.md
@@ -5,7 +5,7 @@ Backports in Clippy are rare and should be approved by the Clippy team. For
 example, a backport is done, if a crucial ICE was fixed or a lint is broken to a
 point, that it has to be disabled, before landing on stable.
 
-Backports are done to the `beta` release of Clippy. Backports to stable Clippy
+Backports are done to the `beta` branch of Clippy. Backports to stable Clippy
 releases basically don't exist, since this would require a Rust point release,
 which is almost never justifiable for a Clippy fix.
 
@@ -18,7 +18,31 @@ Backports are done on the beta branch of the Clippy repository.
 # Assuming the current directory corresponds to the Clippy repository
 $ git checkout beta
 $ git checkout -b backport
-$ git cherry-pick <SHA>  # `<SHA>` is the commit hash of the commit, that should be backported
+$ git cherry-pick <SHA>  # `<SHA>` is the commit hash of the commit(s), that should be backported
+$ git push origin backport
+```
+
+Now you should test that the backport passes all the tests in the Rust
+repository. You can do this with:
+
+```bash
+# Assuming the current directory corresponds to the Rust repository
+$ git checkout beta
+$ git subtree pull -p src/tools/clippy https://github.com/<your-github-name>/rust-clippy backport
+$ ./x.py test src/tools/clippy
+```
+
+Should the test fail, you can fix Clippy directly in the Rust repository. This
+has to be first applied to the Clippy beta branch and then again synced to the
+Rust repository, though. The easiest way to do this is:
+
+```bash
+# In the Rust repository
+$ git diff --patch --relative=src/tools/clippy > clippy.patch
+# In the Clippy repository
+$ git apply /path/to/clippy.patch
+$ git add -u
+$ git commit -m "Fix rustup fallout"
 $ git push origin backport
 ```
 
@@ -29,22 +53,19 @@ After this, you can open a PR to the `beta` branch of the Clippy repository.
 
 This step must be done, **after** the PR of the previous step was merged.
 
-After the backport landed in the Clippy repository, also the Clippy version on
-the Rust `beta` branch has to be updated.
+After the backport landed in the Clippy repository, the branch has to be synced
+back to the beta branch of the Rust repository.
 
 ```bash
 # Assuming the current directory corresponds to the Rust repository
 $ git checkout beta
 $ git checkout -b clippy_backport
-$ pushd src/tools/clippy
-$ git fetch
-$ git checkout beta
-$ popd
-$ git add src/tools/clippy
-§ git commit -m "Update Clippy"
+$ git subtree pull -p src/tools/clippy https://github.com/rust-lang/rust-clippy beta
 $ git push origin clippy_backport
 ```
 
-After this you can open a PR to the `beta` branch of the Rust repository. In
-this PR you should tag the Clippy team member, that agreed to the backport or
-the `@rust-lang/clippy` team. Make sure to add `[beta]` to the title of the PR.
+Make sure to test the backport in the Rust repository before opening a PR. This
+is done with `./x.py test src/tools/clippy`. If that passes all tests, open a PR
+to the `beta` branch of the Rust repository. In this PR you should tag the
+Clippy team member, that agreed to the backport or the `@rust-lang/clippy` team.
+Make sure to add `[beta]` to the title of the PR.
diff --git a/doc/basics.md b/doc/basics.md
index 38959e2331b..f25edb793e2 100644
--- a/doc/basics.md
+++ b/doc/basics.md
@@ -46,7 +46,7 @@ this toolchain, you can just use the `setup-toolchain.sh` script or use
 `rustup-toolchain-install-master`:
 
 ```bash
-sh setup-toolchain.sh
+bash setup-toolchain.sh
 # OR
 cargo install rustup-toolchain-install-master
 # For better IDE integration also add `-c rustfmt -c rust-src` (optional)
diff --git a/doc/common_tools_writing_lints.md b/doc/common_tools_writing_lints.md
index 53c3d084dbc..d56079a4ab7 100644
--- a/doc/common_tools_writing_lints.md
+++ b/doc/common_tools_writing_lints.md
@@ -45,11 +45,13 @@ Similarly in [`TypeckResults`][TypeckResults] methods, you have the [`pat_ty()`]
 to retrieve a type from a pattern.
 
 Two noticeable items here:
-- `cx` is the lint context [`LateContext`][LateContext].
-  The two most useful data structures in this context are `tcx` and `tables`,
-  allowing us to jump to type definitions and other compilation stages such as HIR.
-- `tables` is [`TypeckResults`][TypeckResults] and is created by type checking step,
-  it includes useful information such as types of expressions, ways to resolve methods and so on.
+- `cx` is the lint context [`LateContext`][LateContext]. The two most useful
+  data structures in this context are `tcx` and the `TypeckResults` returned by
+  `LateContext::typeck_results`, allowing us to jump to type definitions and
+  other compilation stages such as HIR.
+- `typeck_results`'s return value is [`TypeckResults`][TypeckResults] and is
+  created by type checking step, it includes useful information such as types
+  of expressions, ways to resolve methods and so on.
 
 # Checking if an expr is calling a specific method
 
diff --git a/doc/release.md b/doc/release.md
index 391952ea6b1..eaa6a9af277 100644
--- a/doc/release.md
+++ b/doc/release.md
@@ -68,7 +68,7 @@ be updated.
 ```bash
 # Assuming the current directory corresponds to the Clippy repository
 $ git checkout beta
-$ git rebase $BETA_SHA
+$ git reset --hard $BETA_SHA
 $ git push upstream beta
 ```
 
diff --git a/src/driver.rs b/src/driver.rs
index 805828eece1..cc71cc66b92 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -1,4 +1,5 @@
 #![feature(rustc_private)]
+#![feature(once_cell)]
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 // warn on lints, that are included in `rust-lang/rust`s bootstrap
 #![warn(rust_2018_idioms, unused_lifetimes)]
@@ -17,9 +18,9 @@ use rustc_interface::interface;
 use rustc_middle::ty::TyCtxt;
 use rustc_tools_util::VersionInfo;
 
-use lazy_static::lazy_static;
 use std::borrow::Cow;
 use std::env;
+use std::lazy::SyncLazy;
 use std::ops::Deref;
 use std::panic;
 use std::path::{Path, PathBuf};
@@ -230,13 +231,11 @@ You can use tool lints to allow or deny lints from your code, eg.:
 
 const BUG_REPORT_URL: &str = "https://github.com/rust-lang/rust-clippy/issues/new";
 
-lazy_static! {
-    static ref ICE_HOOK: Box<dyn Fn(&panic::PanicInfo<'_>) + Sync + Send + 'static> = {
-        let hook = panic::take_hook();
-        panic::set_hook(Box::new(|info| report_clippy_ice(info, BUG_REPORT_URL)));
-        hook
-    };
-}
+static ICE_HOOK: SyncLazy<Box<dyn Fn(&panic::PanicInfo<'_>) + Sync + Send + 'static>> = SyncLazy::new(|| {
+    let hook = panic::take_hook();
+    panic::set_hook(Box::new(|info| report_clippy_ice(info, BUG_REPORT_URL)));
+    hook
+});
 
 fn report_clippy_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
     // Invoke our ICE handler, which prints the actual panic message and optionally a backtrace
@@ -295,7 +294,7 @@ fn toolchain_path(home: Option<String>, toolchain: Option<String>) -> Option<Pat
 
 pub fn main() {
     rustc_driver::init_rustc_env_logger();
-    lazy_static::initialize(&ICE_HOOK);
+    SyncLazy::force(&ICE_HOOK);
     exit(rustc_driver::catch_with_exit_code(move || {
         let mut orig_args: Vec<String> = env::args().collect();
 
diff --git a/src/lintlist/mod.rs b/src/lintlist/mod.rs
index ce3d0efab3a..6301d623a2b 100644
--- a/src/lintlist/mod.rs
+++ b/src/lintlist/mod.rs
@@ -1,15 +1,16 @@
-//! This file is managed by `cargo dev update_lints`. Do not edit.
+//! This file is managed by `cargo dev update_lints`. Do not edit or format this file.
 
-use lazy_static::lazy_static;
+use std::lazy::SyncLazy;
 
 pub mod lint;
 pub use lint::Level;
 pub use lint::Lint;
 pub use lint::LINT_LEVELS;
 
-lazy_static! {
+#[rustfmt::skip]
+pub static ALL_LINTS: SyncLazy<Vec<Lint>> = SyncLazy::new(|| {
 // begin lint list, do not remove this comment, it’s used in `update_lints`
-pub static ref ALL_LINTS: Vec<Lint> = vec![
+vec![
     Lint {
         name: "absurd_extreme_comparisons",
         group: "correctness",
@@ -1180,6 +1181,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         module: "swap",
     },
     Lint {
+        name: "manual_unwrap_or",
+        group: "complexity",
+        desc: "finds patterns that can be encoded more concisely with `Option::unwrap_or`",
+        deprecation: None,
+        module: "manual_unwrap_or",
+    },
+    Lint {
         name: "many_single_char_names",
         group: "style",
         desc: "too many single character bindings",
@@ -1845,6 +1853,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         module: "ptr",
     },
     Lint {
+        name: "ptr_eq",
+        group: "style",
+        desc: "use `std::ptr::eq` when comparing raw pointers",
+        deprecation: None,
+        module: "ptr_eq",
+    },
+    Lint {
         name: "ptr_offset_with_cast",
         group: "complexity",
         desc: "unneeded pointer offset cast",
@@ -1999,6 +2014,13 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         module: "map_unit_fn",
     },
     Lint {
+        name: "result_unit_err",
+        group: "style",
+        desc: "public function returning `Result` with an `Err` type of `()`",
+        deprecation: None,
+        module: "functions",
+    },
+    Lint {
         name: "reversed_empty_ranges",
         group: "correctness",
         desc: "reversing the limits of range expressions, resulting in empty ranges",
@@ -2817,6 +2839,6 @@ pub static ref ALL_LINTS: Vec<Lint> = vec![
         deprecation: None,
         module: "methods",
     },
-];
+]
 // end lint list, do not remove this comment, it’s used in `update_lints`
-}
+});
diff --git a/tests/ui-cargo/update-references.sh b/tests/ui-cargo/update-references.sh
index 50d42678734..2ab51168bca 100755
--- a/tests/ui-cargo/update-references.sh
+++ b/tests/ui-cargo/update-references.sh
@@ -29,10 +29,18 @@ while [[ "$1" != "" ]]; do
            ! (cmp -s -- "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"); then
         echo updating "$MYDIR"/"$STDOUT_NAME"
         cp "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"
+        if [[ ! -s "$MYDIR"/"$STDOUT_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDOUT_NAME"
+            rm "$MYDIR"/"$STDOUT_NAME"
+        fi
     fi
     if [[ -f "$BUILD_DIR"/"$STDERR_NAME" ]] && \
            ! (cmp -s -- "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"); then
         echo updating "$MYDIR"/"$STDERR_NAME"
         cp "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"
+        if [[ ! -s "$MYDIR"/"$STDERR_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDERR_NAME"
+            rm "$MYDIR"/"$STDERR_NAME"
+        fi
     fi
 done
diff --git a/tests/ui-toml/update-references.sh b/tests/ui-toml/update-references.sh
index 50d42678734..2ab51168bca 100755
--- a/tests/ui-toml/update-references.sh
+++ b/tests/ui-toml/update-references.sh
@@ -29,10 +29,18 @@ while [[ "$1" != "" ]]; do
            ! (cmp -s -- "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"); then
         echo updating "$MYDIR"/"$STDOUT_NAME"
         cp "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"
+        if [[ ! -s "$MYDIR"/"$STDOUT_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDOUT_NAME"
+            rm "$MYDIR"/"$STDOUT_NAME"
+        fi
     fi
     if [[ -f "$BUILD_DIR"/"$STDERR_NAME" ]] && \
            ! (cmp -s -- "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"); then
         echo updating "$MYDIR"/"$STDERR_NAME"
         cp "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"
+        if [[ ! -s "$MYDIR"/"$STDERR_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDERR_NAME"
+            rm "$MYDIR"/"$STDERR_NAME"
+        fi
     fi
 done
diff --git a/tests/ui/auxiliary/proc_macro_derive.rs b/tests/ui/auxiliary/proc_macro_derive.rs
index cd5a5ae0aa7..7c4e4a14551 100644
--- a/tests/ui/auxiliary/proc_macro_derive.rs
+++ b/tests/ui/auxiliary/proc_macro_derive.rs
@@ -4,6 +4,7 @@
 #![crate_type = "proc-macro"]
 #![feature(repr128, proc_macro_quote)]
 #![allow(incomplete_features)]
+#![allow(clippy::eq_op)]
 
 extern crate proc_macro;
 
diff --git a/tests/ui/crashes/ice-6139.rs b/tests/ui/crashes/ice-6139.rs
new file mode 100644
index 00000000000..f3966e47f5e
--- /dev/null
+++ b/tests/ui/crashes/ice-6139.rs
@@ -0,0 +1,7 @@
+trait T<'a> {}
+
+fn foo(_: Vec<Box<dyn T<'_>>>) {}
+
+fn main() {
+    foo(vec![]);
+}
diff --git a/tests/ui/crashes/ice-6153.rs b/tests/ui/crashes/ice-6153.rs
new file mode 100644
index 00000000000..9f73f39f10d
--- /dev/null
+++ b/tests/ui/crashes/ice-6153.rs
@@ -0,0 +1,9 @@
+pub struct S<'a, 'e>(&'a str, &'e str);
+
+pub type T<'a, 'e> = std::collections::HashMap<S<'a, 'e>, ()>;
+
+impl<'e, 'a: 'e> S<'a, 'e> {
+    pub fn foo(_a: &str, _b: &str, _map: &T) {}
+}
+
+fn main() {}
diff --git a/tests/ui/doc_errors.rs b/tests/ui/doc_errors.rs
index 445fc8d31d7..f47b81a450e 100644
--- a/tests/ui/doc_errors.rs
+++ b/tests/ui/doc_errors.rs
@@ -1,5 +1,6 @@
 // edition:2018
 #![warn(clippy::missing_errors_doc)]
+#![allow(clippy::result_unit_err)]
 
 use std::io;
 
diff --git a/tests/ui/doc_errors.stderr b/tests/ui/doc_errors.stderr
index f44d6693d30..c7b616e2897 100644
--- a/tests/ui/doc_errors.stderr
+++ b/tests/ui/doc_errors.stderr
@@ -1,5 +1,5 @@
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:6:1
+  --> $DIR/doc_errors.rs:7:1
    |
 LL | / pub fn pub_fn_missing_errors_header() -> Result<(), ()> {
 LL | |     unimplemented!();
@@ -9,7 +9,7 @@ LL | | }
    = note: `-D clippy::missing-errors-doc` implied by `-D warnings`
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:10:1
+  --> $DIR/doc_errors.rs:11:1
    |
 LL | / pub async fn async_pub_fn_missing_errors_header() -> Result<(), ()> {
 LL | |     unimplemented!();
@@ -17,7 +17,7 @@ LL | | }
    | |_^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:15:1
+  --> $DIR/doc_errors.rs:16:1
    |
 LL | / pub fn pub_fn_returning_io_result() -> io::Result<()> {
 LL | |     unimplemented!();
@@ -25,7 +25,7 @@ LL | | }
    | |_^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:20:1
+  --> $DIR/doc_errors.rs:21:1
    |
 LL | / pub async fn async_pub_fn_returning_io_result() -> io::Result<()> {
 LL | |     unimplemented!();
@@ -33,7 +33,7 @@ LL | | }
    | |_^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:50:5
+  --> $DIR/doc_errors.rs:51:5
    |
 LL | /     pub fn pub_method_missing_errors_header() -> Result<(), ()> {
 LL | |         unimplemented!();
@@ -41,7 +41,7 @@ LL | |     }
    | |_____^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:55:5
+  --> $DIR/doc_errors.rs:56:5
    |
 LL | /     pub async fn async_pub_method_missing_errors_header() -> Result<(), ()> {
 LL | |         unimplemented!();
@@ -49,7 +49,7 @@ LL | |     }
    | |_____^
 
 error: docs for function returning `Result` missing `# Errors` section
-  --> $DIR/doc_errors.rs:84:5
+  --> $DIR/doc_errors.rs:85:5
    |
 LL |     fn trait_method_missing_errors_header() -> Result<(), ()>;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/double_must_use.rs b/tests/ui/double_must_use.rs
index a48e675e4ea..05e087b08bc 100644
--- a/tests/ui/double_must_use.rs
+++ b/tests/ui/double_must_use.rs
@@ -1,4 +1,5 @@
 #![warn(clippy::double_must_use)]
+#![allow(clippy::result_unit_err)]
 
 #[must_use]
 pub fn must_use_result() -> Result<(), ()> {
diff --git a/tests/ui/double_must_use.stderr b/tests/ui/double_must_use.stderr
index bc37785294f..8290ece1cad 100644
--- a/tests/ui/double_must_use.stderr
+++ b/tests/ui/double_must_use.stderr
@@ -1,5 +1,5 @@
 error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
-  --> $DIR/double_must_use.rs:4:1
+  --> $DIR/double_must_use.rs:5:1
    |
 LL | pub fn must_use_result() -> Result<(), ()> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -8,7 +8,7 @@ LL | pub fn must_use_result() -> Result<(), ()> {
    = help: either add some descriptive text or remove the attribute
 
 error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
-  --> $DIR/double_must_use.rs:9:1
+  --> $DIR/double_must_use.rs:10:1
    |
 LL | pub fn must_use_tuple() -> (Result<(), ()>, u8) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -16,7 +16,7 @@ LL | pub fn must_use_tuple() -> (Result<(), ()>, u8) {
    = help: either add some descriptive text or remove the attribute
 
 error: this function has an empty `#[must_use]` attribute, but returns a type already marked as `#[must_use]`
-  --> $DIR/double_must_use.rs:14:1
+  --> $DIR/double_must_use.rs:15:1
    |
 LL | pub fn must_use_array() -> [Result<(), ()>; 1] {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/double_parens.rs b/tests/ui/double_parens.rs
index 9c7590c7dd6..ff1dc76ab63 100644
--- a/tests/ui/double_parens.rs
+++ b/tests/ui/double_parens.rs
@@ -1,5 +1,5 @@
 #![warn(clippy::double_parens)]
-#![allow(dead_code)]
+#![allow(dead_code, clippy::eq_op)]
 #![feature(custom_inner_attributes)]
 #![rustfmt::skip]
 
diff --git a/tests/ui/eq_op_macros.rs b/tests/ui/eq_op_macros.rs
new file mode 100644
index 00000000000..6b5b31a1a2e
--- /dev/null
+++ b/tests/ui/eq_op_macros.rs
@@ -0,0 +1,56 @@
+#![warn(clippy::eq_op)]
+
+// lint also in macro definition
+macro_rules! assert_in_macro_def {
+    () => {
+        let a = 42;
+        assert_eq!(a, a);
+        assert_ne!(a, a);
+        debug_assert_eq!(a, a);
+        debug_assert_ne!(a, a);
+    };
+}
+
+// lint identical args in assert-like macro invocations (see #3574)
+fn main() {
+    assert_in_macro_def!();
+
+    let a = 1;
+    let b = 2;
+
+    // lint identical args in `assert_eq!`
+    assert_eq!(a, a);
+    assert_eq!(a + 1, a + 1);
+    // ok
+    assert_eq!(a, b);
+    assert_eq!(a, a + 1);
+    assert_eq!(a + 1, b + 1);
+
+    // lint identical args in `assert_ne!`
+    assert_ne!(a, a);
+    assert_ne!(a + 1, a + 1);
+    // ok
+    assert_ne!(a, b);
+    assert_ne!(a, a + 1);
+    assert_ne!(a + 1, b + 1);
+
+    // lint identical args in `debug_assert_eq!`
+    debug_assert_eq!(a, a);
+    debug_assert_eq!(a + 1, a + 1);
+    // ok
+    debug_assert_eq!(a, b);
+    debug_assert_eq!(a, a + 1);
+    debug_assert_eq!(a + 1, b + 1);
+
+    // lint identical args in `debug_assert_ne!`
+    debug_assert_ne!(a, a);
+    debug_assert_ne!(a + 1, a + 1);
+    // ok
+    debug_assert_ne!(a, b);
+    debug_assert_ne!(a, a + 1);
+    debug_assert_ne!(a + 1, b + 1);
+
+    let my_vec = vec![1; 5];
+    let mut my_iter = my_vec.iter();
+    assert_ne!(my_iter.next(), my_iter.next());
+}
diff --git a/tests/ui/eq_op_macros.stderr b/tests/ui/eq_op_macros.stderr
new file mode 100644
index 00000000000..fb9378108b9
--- /dev/null
+++ b/tests/ui/eq_op_macros.stderr
@@ -0,0 +1,95 @@
+error: identical args used in this `assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:7:20
+   |
+LL |         assert_eq!(a, a);
+   |                    ^^^^
+...
+LL |     assert_in_macro_def!();
+   |     ----------------------- in this macro invocation
+   |
+   = note: `-D clippy::eq-op` implied by `-D warnings`
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: identical args used in this `assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:8:20
+   |
+LL |         assert_ne!(a, a);
+   |                    ^^^^
+...
+LL |     assert_in_macro_def!();
+   |     ----------------------- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: identical args used in this `assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:22:16
+   |
+LL |     assert_eq!(a, a);
+   |                ^^^^
+
+error: identical args used in this `assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:23:16
+   |
+LL |     assert_eq!(a + 1, a + 1);
+   |                ^^^^^^^^^^^^
+
+error: identical args used in this `assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:30:16
+   |
+LL |     assert_ne!(a, a);
+   |                ^^^^
+
+error: identical args used in this `assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:31:16
+   |
+LL |     assert_ne!(a + 1, a + 1);
+   |                ^^^^^^^^^^^^
+
+error: identical args used in this `debug_assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:9:26
+   |
+LL |         debug_assert_eq!(a, a);
+   |                          ^^^^
+...
+LL |     assert_in_macro_def!();
+   |     ----------------------- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: identical args used in this `debug_assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:10:26
+   |
+LL |         debug_assert_ne!(a, a);
+   |                          ^^^^
+...
+LL |     assert_in_macro_def!();
+   |     ----------------------- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: identical args used in this `debug_assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:38:22
+   |
+LL |     debug_assert_eq!(a, a);
+   |                      ^^^^
+
+error: identical args used in this `debug_assert_eq!` macro call
+  --> $DIR/eq_op_macros.rs:39:22
+   |
+LL |     debug_assert_eq!(a + 1, a + 1);
+   |                      ^^^^^^^^^^^^
+
+error: identical args used in this `debug_assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:46:22
+   |
+LL |     debug_assert_ne!(a, a);
+   |                      ^^^^
+
+error: identical args used in this `debug_assert_ne!` macro call
+  --> $DIR/eq_op_macros.rs:47:22
+   |
+LL |     debug_assert_ne!(a + 1, a + 1);
+   |                      ^^^^^^^^^^^^
+
+error: aborting due to 12 previous errors
+
diff --git a/tests/ui/float_cmp.rs b/tests/ui/float_cmp.rs
index 9fa0e5f5c07..586784b73e6 100644
--- a/tests/ui/float_cmp.rs
+++ b/tests/ui/float_cmp.rs
@@ -2,6 +2,7 @@
 #![allow(
     unused,
     clippy::no_effect,
+    clippy::op_ref,
     clippy::unnecessary_operation,
     clippy::cast_lossless,
     clippy::many_single_char_names
@@ -116,4 +117,8 @@ fn main() {
     1.23f64.signum() != x64.signum();
     1.23f64.signum() != -(x64.signum());
     1.23f64.signum() != 3.21f64.signum();
+
+    // the comparison should also look through references
+    &0.0 == &ZERO;
+    &&&&0.0 == &&&&ZERO;
 }
diff --git a/tests/ui/float_cmp.stderr b/tests/ui/float_cmp.stderr
index f7c380fc915..bb4051c4662 100644
--- a/tests/ui/float_cmp.stderr
+++ b/tests/ui/float_cmp.stderr
@@ -1,5 +1,5 @@
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:65:5
+  --> $DIR/float_cmp.rs:66:5
    |
 LL |     ONE as f64 != 2.0;
    |     ^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(ONE as f64 - 2.0).abs() > error_margin`
@@ -8,7 +8,7 @@ LL |     ONE as f64 != 2.0;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:70:5
+  --> $DIR/float_cmp.rs:71:5
    |
 LL |     x == 1.0;
    |     ^^^^^^^^ help: consider comparing them within some margin of error: `(x - 1.0).abs() < error_margin`
@@ -16,7 +16,7 @@ LL |     x == 1.0;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:73:5
+  --> $DIR/float_cmp.rs:74:5
    |
 LL |     twice(x) != twice(ONE as f64);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(twice(x) - twice(ONE as f64)).abs() > error_margin`
@@ -24,7 +24,7 @@ LL |     twice(x) != twice(ONE as f64);
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:93:5
+  --> $DIR/float_cmp.rs:94:5
    |
 LL |     NON_ZERO_ARRAY[i] == NON_ZERO_ARRAY[j];
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(NON_ZERO_ARRAY[i] - NON_ZERO_ARRAY[j]).abs() < error_margin`
@@ -32,7 +32,7 @@ LL |     NON_ZERO_ARRAY[i] == NON_ZERO_ARRAY[j];
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64` arrays
-  --> $DIR/float_cmp.rs:98:5
+  --> $DIR/float_cmp.rs:99:5
    |
 LL |     a1 == a2;
    |     ^^^^^^^^
@@ -40,7 +40,7 @@ LL |     a1 == a2;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:99:5
+  --> $DIR/float_cmp.rs:100:5
    |
 LL |     a1[0] == a2[0];
    |     ^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(a1[0] - a2[0]).abs() < error_margin`
diff --git a/tests/ui/format.fixed b/tests/ui/format.fixed
index 30651476999..740a22a07d7 100644
--- a/tests/ui/format.fixed
+++ b/tests/ui/format.fixed
@@ -13,7 +13,8 @@ fn main() {
     "foo".to_string();
     "{}".to_string();
     "{} abc {}".to_string();
-    "foo {}\n\" bar".to_string();
+    r##"foo {}
+" bar"##.to_string();
 
     "foo".to_string();
     format!("{:?}", "foo"); // Don't warn about `Debug`.
diff --git a/tests/ui/format.stderr b/tests/ui/format.stderr
index 9734492154e..96df7f37f77 100644
--- a/tests/ui/format.stderr
+++ b/tests/ui/format.stderr
@@ -25,7 +25,13 @@ LL | /     format!(
 LL | |         r##"foo {{}}
 LL | | " bar"##
 LL | |     );
-   | |______^ help: consider using `.to_string()`: `"foo {}/n/" bar".to_string();`
+   | |______^
+   |
+help: consider using `.to_string()`
+   |
+LL |     r##"foo {}
+LL | " bar"##.to_string();
+   |
 
 error: useless use of `format!`
   --> $DIR/format.rs:21:5
diff --git a/tests/ui/manual_memcpy.stderr b/tests/ui/manual_memcpy.stderr
deleted file mode 100644
index bad84a58900..00000000000
--- a/tests/ui/manual_memcpy.stderr
+++ /dev/null
@@ -1,88 +0,0 @@
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:7:14
-   |
-LL |     for i in 0..src.len() {
-   |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..])`
-   |
-   = note: `-D clippy::manual-memcpy` implied by `-D warnings`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:12:14
-   |
-LL |     for i in 0..src.len() {
-   |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[10..(src.len() + 10)].clone_from_slice(&src[..])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:17:14
-   |
-LL |     for i in 0..src.len() {
-   |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[10..])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:22:14
-   |
-LL |     for i in 11..src.len() {
-   |              ^^^^^^^^^^^^^ help: try replacing the loop by: `dst[11..src.len()].clone_from_slice(&src[(11 - 10)..(src.len() - 10)])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:27:14
-   |
-LL |     for i in 0..dst.len() {
-   |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst.clone_from_slice(&src[..dst.len()])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:40:14
-   |
-LL |     for i in 10..256 {
-   |              ^^^^^^^
-   |
-help: try replacing the loop by
-   |
-LL |     for i in dst[10..256].clone_from_slice(&src[(10 - 5)..(256 - 5)])
-LL |     dst2[(10 + 500)..(256 + 500)].clone_from_slice(&src[10..256]) {
-   |
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:52:14
-   |
-LL |     for i in 10..LOOP_OFFSET {
-   |              ^^^^^^^^^^^^^^^ help: try replacing the loop by: `dst[(10 + LOOP_OFFSET)..(LOOP_OFFSET + LOOP_OFFSET)].clone_from_slice(&src[(10 - some_var)..(LOOP_OFFSET - some_var)])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:65:14
-   |
-LL |     for i in 0..src_vec.len() {
-   |              ^^^^^^^^^^^^^^^^ help: try replacing the loop by: `dst_vec[..src_vec.len()].clone_from_slice(&src_vec[..])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:94:14
-   |
-LL |     for i in from..from + src.len() {
-   |              ^^^^^^^^^^^^^^^^^^^^^^ help: try replacing the loop by: `dst[from..from + src.len()].clone_from_slice(&src[..(from + src.len() - from)])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:98:14
-   |
-LL |     for i in from..from + 3 {
-   |              ^^^^^^^^^^^^^^ help: try replacing the loop by: `dst[from..from + 3].clone_from_slice(&src[..(from + 3 - from)])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:103:14
-   |
-LL |     for i in 0..5 {
-   |              ^^^^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:108:14
-   |
-LL |     for i in 0..0 {
-   |              ^^^^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0])`
-
-error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:120:14
-   |
-LL |     for i in 0..src.len() {
-   |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..])`
-
-error: aborting due to 13 previous errors
-
diff --git a/tests/ui/manual_memcpy/with_loop_counters.rs b/tests/ui/manual_memcpy/with_loop_counters.rs
new file mode 100644
index 00000000000..ba388a05a28
--- /dev/null
+++ b/tests/ui/manual_memcpy/with_loop_counters.rs
@@ -0,0 +1,88 @@
+#![warn(clippy::needless_range_loop, clippy::manual_memcpy)]
+
+pub fn manual_copy_with_counters(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) {
+    let mut count = 0;
+    for i in 3..src.len() {
+        dst[i] = src[count];
+        count += 1;
+    }
+
+    let mut count = 0;
+    for i in 3..src.len() {
+        dst[count] = src[i];
+        count += 1;
+    }
+
+    let mut count = 3;
+    for i in 0..src.len() {
+        dst[count] = src[i];
+        count += 1;
+    }
+
+    let mut count = 3;
+    for i in 0..src.len() {
+        dst[i] = src[count];
+        count += 1;
+    }
+
+    let mut count = 0;
+    for i in 3..(3 + src.len()) {
+        dst[i] = src[count];
+        count += 1;
+    }
+
+    let mut count = 3;
+    for i in 5..src.len() {
+        dst[i] = src[count - 2];
+        count += 1;
+    }
+
+    let mut count = 2;
+    for i in 0..dst.len() {
+        dst[i] = src[count];
+        count += 1;
+    }
+
+    let mut count = 5;
+    for i in 3..10 {
+        dst[i] = src[count];
+        count += 1;
+    }
+
+    let mut count = 3;
+    let mut count2 = 30;
+    for i in 0..src.len() {
+        dst[count] = src[i];
+        dst2[count2] = src[i];
+        count += 1;
+        count2 += 1;
+    }
+
+    // make sure parentheses are added properly to bitwise operators, which have lower precedence than
+    // arithmetric ones
+    let mut count = 0 << 1;
+    for i in 0..1 << 1 {
+        dst[count] = src[i + 2];
+        count += 1;
+    }
+
+    // make sure incrementing expressions without semicolons at the end of loops are handled correctly.
+    let mut count = 0;
+    for i in 3..src.len() {
+        dst[i] = src[count];
+        count += 1
+    }
+
+    // make sure ones where the increment is not at the end of the loop.
+    // As a possible enhancement, one could adjust the offset in the suggestion according to
+    // the position. For example, if the increment is at the top of the loop;
+    // treating the loop counter as if it were initialized 1 greater than the original value.
+    let mut count = 0;
+    #[allow(clippy::needless_range_loop)]
+    for i in 0..src.len() {
+        count += 1;
+        dst[i] = src[count];
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/manual_memcpy/with_loop_counters.stderr b/tests/ui/manual_memcpy/with_loop_counters.stderr
new file mode 100644
index 00000000000..2547b19f5d1
--- /dev/null
+++ b/tests/ui/manual_memcpy/with_loop_counters.stderr
@@ -0,0 +1,111 @@
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:5:5
+   |
+LL | /     for i in 3..src.len() {
+LL | |         dst[i] = src[count];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[3..src.len()].clone_from_slice(&src[..(src.len() - 3)]);`
+   |
+   = note: `-D clippy::manual-memcpy` implied by `-D warnings`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:11:5
+   |
+LL | /     for i in 3..src.len() {
+LL | |         dst[count] = src[i];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..(src.len() - 3)].clone_from_slice(&src[3..]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:17:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[count] = src[i];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[3..(src.len() + 3)].clone_from_slice(&src[..]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:23:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[i] = src[count];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[3..(src.len() + 3)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:29:5
+   |
+LL | /     for i in 3..(3 + src.len()) {
+LL | |         dst[i] = src[count];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[3..((3 + src.len()))].clone_from_slice(&src[..((3 + src.len()) - 3)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:35:5
+   |
+LL | /     for i in 5..src.len() {
+LL | |         dst[i] = src[count - 2];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[5..src.len()].clone_from_slice(&src[(3 - 2)..((src.len() - 2) + 3 - 5)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:41:5
+   |
+LL | /     for i in 0..dst.len() {
+LL | |         dst[i] = src[count];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst.clone_from_slice(&src[2..(dst.len() + 2)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:47:5
+   |
+LL | /     for i in 3..10 {
+LL | |         dst[i] = src[count];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[3..10].clone_from_slice(&src[5..(10 + 5 - 3)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:54:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[count] = src[i];
+LL | |         dst2[count2] = src[i];
+LL | |         count += 1;
+LL | |         count2 += 1;
+LL | |     }
+   | |_____^
+   |
+help: try replacing the loop by
+   |
+LL |     dst[3..(src.len() + 3)].clone_from_slice(&src[..]);
+LL |     dst2[30..(src.len() + 30)].clone_from_slice(&src[..]);
+   |
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:64:5
+   |
+LL | /     for i in 0..1 << 1 {
+LL | |         dst[count] = src[i + 2];
+LL | |         count += 1;
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[(0 << 1)..((1 << 1) + (0 << 1))].clone_from_slice(&src[2..((1 << 1) + 2)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/with_loop_counters.rs:71:5
+   |
+LL | /     for i in 3..src.len() {
+LL | |         dst[i] = src[count];
+LL | |         count += 1
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[3..src.len()].clone_from_slice(&src[..(src.len() - 3)]);`
+
+error: aborting due to 11 previous errors
+
diff --git a/tests/ui/manual_memcpy.rs b/tests/ui/manual_memcpy/without_loop_counters.rs
index 0083f94798f..0083f94798f 100644
--- a/tests/ui/manual_memcpy.rs
+++ b/tests/ui/manual_memcpy/without_loop_counters.rs
diff --git a/tests/ui/manual_memcpy/without_loop_counters.stderr b/tests/ui/manual_memcpy/without_loop_counters.stderr
new file mode 100644
index 00000000000..54b966f6e54
--- /dev/null
+++ b/tests/ui/manual_memcpy/without_loop_counters.stderr
@@ -0,0 +1,115 @@
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:7:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[i] = src[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..]);`
+   |
+   = note: `-D clippy::manual-memcpy` implied by `-D warnings`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:12:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[i + 10] = src[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[10..(src.len() + 10)].clone_from_slice(&src[..]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:17:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[i] = src[i + 10];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[10..(src.len() + 10)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:22:5
+   |
+LL | /     for i in 11..src.len() {
+LL | |         dst[i] = src[i - 10];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[11..src.len()].clone_from_slice(&src[(11 - 10)..(src.len() - 10)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:27:5
+   |
+LL | /     for i in 0..dst.len() {
+LL | |         dst[i] = src[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst.clone_from_slice(&src[..dst.len()]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:40:5
+   |
+LL | /     for i in 10..256 {
+LL | |         dst[i] = src[i - 5];
+LL | |         dst2[i + 500] = src[i]
+LL | |     }
+   | |_____^
+   |
+help: try replacing the loop by
+   |
+LL |     dst[10..256].clone_from_slice(&src[(10 - 5)..(256 - 5)]);
+LL |     dst2[(10 + 500)..(256 + 500)].clone_from_slice(&src[10..256]);
+   |
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:52:5
+   |
+LL | /     for i in 10..LOOP_OFFSET {
+LL | |         dst[i + LOOP_OFFSET] = src[i - some_var];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[(10 + LOOP_OFFSET)..(LOOP_OFFSET + LOOP_OFFSET)].clone_from_slice(&src[(10 - some_var)..(LOOP_OFFSET - some_var)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:65:5
+   |
+LL | /     for i in 0..src_vec.len() {
+LL | |         dst_vec[i] = src_vec[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst_vec[..src_vec.len()].clone_from_slice(&src_vec[..]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:94:5
+   |
+LL | /     for i in from..from + src.len() {
+LL | |         dst[i] = src[i - from];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[from..(from + src.len())].clone_from_slice(&src[..(from + src.len() - from)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:98:5
+   |
+LL | /     for i in from..from + 3 {
+LL | |         dst[i] = src[i - from];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[from..(from + 3)].clone_from_slice(&src[..(from + 3 - from)]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:103:5
+   |
+LL | /     for i in 0..5 {
+LL | |         dst[i - 0] = src[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:108:5
+   |
+LL | /     for i in 0..0 {
+LL | |         dst[i] = src[i];
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0]);`
+
+error: it looks like you're manually copying between slices
+  --> $DIR/without_loop_counters.rs:120:5
+   |
+LL | /     for i in 0..src.len() {
+LL | |         dst[i] = src[i].clone();
+LL | |     }
+   | |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..]);`
+
+error: aborting due to 13 previous errors
+
diff --git a/tests/ui/manual_unwrap_or.fixed b/tests/ui/manual_unwrap_or.fixed
new file mode 100644
index 00000000000..a8736f1e6ef
--- /dev/null
+++ b/tests/ui/manual_unwrap_or.fixed
@@ -0,0 +1,68 @@
+// run-rustfix
+#![allow(dead_code)]
+
+fn unwrap_or() {
+    // int case
+    Some(1).unwrap_or(42);
+
+    // int case reversed
+    Some(1).unwrap_or(42);
+
+    // richer none expr
+    Some(1).unwrap_or(1 + 42);
+
+    // multiline case
+    #[rustfmt::skip]
+    Some(1).unwrap_or({
+        42 + 42
+            + 42 + 42 + 42
+            + 42 + 42 + 42
+    });
+
+    // string case
+    Some("Bob").unwrap_or("Alice");
+
+    // don't lint
+    match Some(1) {
+        Some(i) => i + 2,
+        None => 42,
+    };
+    match Some(1) {
+        Some(i) => i,
+        None => return,
+    };
+    for j in 0..4 {
+        match Some(j) {
+            Some(i) => i,
+            None => continue,
+        };
+        match Some(j) {
+            Some(i) => i,
+            None => break,
+        };
+    }
+
+    // cases where the none arm isn't a constant expression
+    // are not linted due to potential ownership issues
+
+    // ownership issue example, don't lint
+    struct NonCopyable;
+    let mut option: Option<NonCopyable> = None;
+    match option {
+        Some(x) => x,
+        None => {
+            option = Some(NonCopyable);
+            // some more code ...
+            option.unwrap()
+        },
+    };
+
+    // ownership issue example, don't lint
+    let option: Option<&str> = None;
+    match option {
+        Some(s) => s,
+        None => &format!("{} {}!", "hello", "world"),
+    };
+}
+
+fn main() {}
diff --git a/tests/ui/manual_unwrap_or.rs b/tests/ui/manual_unwrap_or.rs
new file mode 100644
index 00000000000..bede8cffc32
--- /dev/null
+++ b/tests/ui/manual_unwrap_or.rs
@@ -0,0 +1,83 @@
+// run-rustfix
+#![allow(dead_code)]
+
+fn unwrap_or() {
+    // int case
+    match Some(1) {
+        Some(i) => i,
+        None => 42,
+    };
+
+    // int case reversed
+    match Some(1) {
+        None => 42,
+        Some(i) => i,
+    };
+
+    // richer none expr
+    match Some(1) {
+        Some(i) => i,
+        None => 1 + 42,
+    };
+
+    // multiline case
+    #[rustfmt::skip]
+    match Some(1) {
+        Some(i) => i,
+        None => {
+            42 + 42
+                + 42 + 42 + 42
+                + 42 + 42 + 42
+        }
+    };
+
+    // string case
+    match Some("Bob") {
+        Some(i) => i,
+        None => "Alice",
+    };
+
+    // don't lint
+    match Some(1) {
+        Some(i) => i + 2,
+        None => 42,
+    };
+    match Some(1) {
+        Some(i) => i,
+        None => return,
+    };
+    for j in 0..4 {
+        match Some(j) {
+            Some(i) => i,
+            None => continue,
+        };
+        match Some(j) {
+            Some(i) => i,
+            None => break,
+        };
+    }
+
+    // cases where the none arm isn't a constant expression
+    // are not linted due to potential ownership issues
+
+    // ownership issue example, don't lint
+    struct NonCopyable;
+    let mut option: Option<NonCopyable> = None;
+    match option {
+        Some(x) => x,
+        None => {
+            option = Some(NonCopyable);
+            // some more code ...
+            option.unwrap()
+        },
+    };
+
+    // ownership issue example, don't lint
+    let option: Option<&str> = None;
+    match option {
+        Some(s) => s,
+        None => &format!("{} {}!", "hello", "world"),
+    };
+}
+
+fn main() {}
diff --git a/tests/ui/manual_unwrap_or.stderr b/tests/ui/manual_unwrap_or.stderr
new file mode 100644
index 00000000000..674f2952635
--- /dev/null
+++ b/tests/ui/manual_unwrap_or.stderr
@@ -0,0 +1,61 @@
+error: this pattern reimplements `Option::unwrap_or`
+  --> $DIR/manual_unwrap_or.rs:6:5
+   |
+LL | /     match Some(1) {
+LL | |         Some(i) => i,
+LL | |         None => 42,
+LL | |     };
+   | |_____^ help: replace with: `Some(1).unwrap_or(42)`
+   |
+   = note: `-D clippy::manual-unwrap-or` implied by `-D warnings`
+
+error: this pattern reimplements `Option::unwrap_or`
+  --> $DIR/manual_unwrap_or.rs:12:5
+   |
+LL | /     match Some(1) {
+LL | |         None => 42,
+LL | |         Some(i) => i,
+LL | |     };
+   | |_____^ help: replace with: `Some(1).unwrap_or(42)`
+
+error: this pattern reimplements `Option::unwrap_or`
+  --> $DIR/manual_unwrap_or.rs:18:5
+   |
+LL | /     match Some(1) {
+LL | |         Some(i) => i,
+LL | |         None => 1 + 42,
+LL | |     };
+   | |_____^ help: replace with: `Some(1).unwrap_or(1 + 42)`
+
+error: this pattern reimplements `Option::unwrap_or`
+  --> $DIR/manual_unwrap_or.rs:25:5
+   |
+LL | /     match Some(1) {
+LL | |         Some(i) => i,
+LL | |         None => {
+LL | |             42 + 42
+...  |
+LL | |         }
+LL | |     };
+   | |_____^
+   |
+help: replace with
+   |
+LL |     Some(1).unwrap_or({
+LL |         42 + 42
+LL |             + 42 + 42 + 42
+LL |             + 42 + 42 + 42
+LL |     });
+   |
+
+error: this pattern reimplements `Option::unwrap_or`
+  --> $DIR/manual_unwrap_or.rs:35:5
+   |
+LL | /     match Some("Bob") {
+LL | |         Some(i) => i,
+LL | |         None => "Alice",
+LL | |     };
+   | |_____^ help: replace with: `Some("Bob").unwrap_or("Alice")`
+
+error: aborting due to 5 previous errors
+
diff --git a/tests/ui/ptr_eq.fixed b/tests/ui/ptr_eq.fixed
new file mode 100644
index 00000000000..209081e6e80
--- /dev/null
+++ b/tests/ui/ptr_eq.fixed
@@ -0,0 +1,38 @@
+// run-rustfix
+#![warn(clippy::ptr_eq)]
+
+macro_rules! mac {
+    ($a:expr, $b:expr) => {
+        $a as *const _ as usize == $b as *const _ as usize
+    };
+}
+
+macro_rules! another_mac {
+    ($a:expr, $b:expr) => {
+        $a as *const _ == $b as *const _
+    };
+}
+
+fn main() {
+    let a = &[1, 2, 3];
+    let b = &[1, 2, 3];
+
+    let _ = std::ptr::eq(a, b);
+    let _ = std::ptr::eq(a, b);
+    let _ = a.as_ptr() == b as *const _;
+    let _ = a.as_ptr() == b.as_ptr();
+
+    // Do not lint
+
+    let _ = mac!(a, b);
+    let _ = another_mac!(a, b);
+
+    let a = &mut [1, 2, 3];
+    let b = &mut [1, 2, 3];
+
+    let _ = a.as_mut_ptr() == b as *mut [i32] as *mut _;
+    let _ = a.as_mut_ptr() == b.as_mut_ptr();
+
+    let _ = a == b;
+    let _ = core::ptr::eq(a, b);
+}
diff --git a/tests/ui/ptr_eq.rs b/tests/ui/ptr_eq.rs
new file mode 100644
index 00000000000..69162870807
--- /dev/null
+++ b/tests/ui/ptr_eq.rs
@@ -0,0 +1,38 @@
+// run-rustfix
+#![warn(clippy::ptr_eq)]
+
+macro_rules! mac {
+    ($a:expr, $b:expr) => {
+        $a as *const _ as usize == $b as *const _ as usize
+    };
+}
+
+macro_rules! another_mac {
+    ($a:expr, $b:expr) => {
+        $a as *const _ == $b as *const _
+    };
+}
+
+fn main() {
+    let a = &[1, 2, 3];
+    let b = &[1, 2, 3];
+
+    let _ = a as *const _ as usize == b as *const _ as usize;
+    let _ = a as *const _ == b as *const _;
+    let _ = a.as_ptr() == b as *const _;
+    let _ = a.as_ptr() == b.as_ptr();
+
+    // Do not lint
+
+    let _ = mac!(a, b);
+    let _ = another_mac!(a, b);
+
+    let a = &mut [1, 2, 3];
+    let b = &mut [1, 2, 3];
+
+    let _ = a.as_mut_ptr() == b as *mut [i32] as *mut _;
+    let _ = a.as_mut_ptr() == b.as_mut_ptr();
+
+    let _ = a == b;
+    let _ = core::ptr::eq(a, b);
+}
diff --git a/tests/ui/ptr_eq.stderr b/tests/ui/ptr_eq.stderr
new file mode 100644
index 00000000000..45d8c60382b
--- /dev/null
+++ b/tests/ui/ptr_eq.stderr
@@ -0,0 +1,16 @@
+error: use `std::ptr::eq` when comparing raw pointers
+  --> $DIR/ptr_eq.rs:20:13
+   |
+LL |     let _ = a as *const _ as usize == b as *const _ as usize;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::ptr::eq(a, b)`
+   |
+   = note: `-D clippy::ptr-eq` implied by `-D warnings`
+
+error: use `std::ptr::eq` when comparing raw pointers
+  --> $DIR/ptr_eq.rs:21:13
+   |
+LL |     let _ = a as *const _ == b as *const _;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::ptr::eq(a, b)`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/result_unit_error.rs b/tests/ui/result_unit_error.rs
new file mode 100644
index 00000000000..a66f581b215
--- /dev/null
+++ b/tests/ui/result_unit_error.rs
@@ -0,0 +1,38 @@
+#[warn(clippy::result_unit_err)]
+#[allow(unused)]
+
+pub fn returns_unit_error() -> Result<u32, ()> {
+    Err(())
+}
+
+fn private_unit_errors() -> Result<String, ()> {
+    Err(())
+}
+
+pub trait HasUnitError {
+    fn get_that_error(&self) -> Result<bool, ()>;
+
+    fn get_this_one_too(&self) -> Result<bool, ()> {
+        Err(())
+    }
+}
+
+impl HasUnitError for () {
+    fn get_that_error(&self) -> Result<bool, ()> {
+        Ok(true)
+    }
+}
+
+trait PrivateUnitError {
+    fn no_problem(&self) -> Result<usize, ()>;
+}
+
+pub struct UnitErrorHolder;
+
+impl UnitErrorHolder {
+    pub fn unit_error(&self) -> Result<usize, ()> {
+        Ok(0)
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/result_unit_error.stderr b/tests/ui/result_unit_error.stderr
new file mode 100644
index 00000000000..b8230032491
--- /dev/null
+++ b/tests/ui/result_unit_error.stderr
@@ -0,0 +1,35 @@
+error: this returns a `Result<_, ()>
+  --> $DIR/result_unit_error.rs:4:1
+   |
+LL | pub fn returns_unit_error() -> Result<u32, ()> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::result-unit-err` implied by `-D warnings`
+   = help: use a custom Error type instead
+
+error: this returns a `Result<_, ()>
+  --> $DIR/result_unit_error.rs:13:5
+   |
+LL |     fn get_that_error(&self) -> Result<bool, ()>;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: use a custom Error type instead
+
+error: this returns a `Result<_, ()>
+  --> $DIR/result_unit_error.rs:15:5
+   |
+LL |     fn get_this_one_too(&self) -> Result<bool, ()> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: use a custom Error type instead
+
+error: this returns a `Result<_, ()>
+  --> $DIR/result_unit_error.rs:33:5
+   |
+LL |     pub fn unit_error(&self) -> Result<usize, ()> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: use a custom Error type instead
+
+error: aborting due to 4 previous errors
+
diff --git a/tests/ui/same_functions_in_if_condition.rs b/tests/ui/same_functions_in_if_condition.rs
index 686867cf5c6..7f28f025790 100644
--- a/tests/ui/same_functions_in_if_condition.rs
+++ b/tests/ui/same_functions_in_if_condition.rs
@@ -77,4 +77,14 @@ fn ifs_same_cond_fn() {
     }
 }
 
-fn main() {}
+fn main() {
+    // macro as condition (see #6168)
+    let os = if cfg!(target_os = "macos") {
+        "macos"
+    } else if cfg!(target_os = "windows") {
+        "windows"
+    } else {
+        "linux"
+    };
+    println!("{}", os);
+}
diff --git a/tests/ui/shadow.rs b/tests/ui/shadow.rs
index bd91ae4e934..e366c75335c 100644
--- a/tests/ui/shadow.rs
+++ b/tests/ui/shadow.rs
@@ -8,6 +8,7 @@
 #![allow(
     unused_parens,
     unused_variables,
+    clippy::manual_unwrap_or,
     clippy::missing_docs_in_private_items,
     clippy::single_match
 )]
diff --git a/tests/ui/shadow.stderr b/tests/ui/shadow.stderr
index 8a831375b41..7c1ad2949e9 100644
--- a/tests/ui/shadow.stderr
+++ b/tests/ui/shadow.stderr
@@ -1,135 +1,135 @@
 error: `x` is shadowed by itself in `&mut x`
-  --> $DIR/shadow.rs:26:5
+  --> $DIR/shadow.rs:27:5
    |
 LL |     let x = &mut x;
    |     ^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::shadow-same` implied by `-D warnings`
 note: previous binding is here
-  --> $DIR/shadow.rs:25:13
+  --> $DIR/shadow.rs:26:13
    |
 LL |     let mut x = 1;
    |             ^
 
 error: `x` is shadowed by itself in `{ x }`
-  --> $DIR/shadow.rs:27:5
+  --> $DIR/shadow.rs:28:5
    |
 LL |     let x = { x };
    |     ^^^^^^^^^^^^^^
    |
 note: previous binding is here
-  --> $DIR/shadow.rs:26:9
+  --> $DIR/shadow.rs:27:9
    |
 LL |     let x = &mut x;
    |         ^
 
 error: `x` is shadowed by itself in `(&*x)`
-  --> $DIR/shadow.rs:28:5
+  --> $DIR/shadow.rs:29:5
    |
 LL |     let x = (&*x);
    |     ^^^^^^^^^^^^^^
    |
 note: previous binding is here
-  --> $DIR/shadow.rs:27:9
+  --> $DIR/shadow.rs:28:9
    |
 LL |     let x = { x };
    |         ^
 
 error: `x` is shadowed by `{ *x + 1 }` which reuses the original value
-  --> $DIR/shadow.rs:29:9
+  --> $DIR/shadow.rs:30:9
    |
 LL |     let x = { *x + 1 };
    |         ^
    |
    = note: `-D clippy::shadow-reuse` implied by `-D warnings`
 note: initialization happens here
-  --> $DIR/shadow.rs:29:13
+  --> $DIR/shadow.rs:30:13
    |
 LL |     let x = { *x + 1 };
    |             ^^^^^^^^^^
 note: previous binding is here
-  --> $DIR/shadow.rs:28:9
+  --> $DIR/shadow.rs:29:9
    |
 LL |     let x = (&*x);
    |         ^
 
 error: `x` is shadowed by `id(x)` which reuses the original value
-  --> $DIR/shadow.rs:30:9
+  --> $DIR/shadow.rs:31:9
    |
 LL |     let x = id(x);
    |         ^
    |
 note: initialization happens here
-  --> $DIR/shadow.rs:30:13
+  --> $DIR/shadow.rs:31:13
    |
 LL |     let x = id(x);
    |             ^^^^^
 note: previous binding is here
-  --> $DIR/shadow.rs:29:9
+  --> $DIR/shadow.rs:30:9
    |
 LL |     let x = { *x + 1 };
    |         ^
 
 error: `x` is shadowed by `(1, x)` which reuses the original value
-  --> $DIR/shadow.rs:31:9
+  --> $DIR/shadow.rs:32:9
    |
 LL |     let x = (1, x);
    |         ^
    |
 note: initialization happens here
-  --> $DIR/shadow.rs:31:13
+  --> $DIR/shadow.rs:32:13
    |
 LL |     let x = (1, x);
    |             ^^^^^^
 note: previous binding is here
-  --> $DIR/shadow.rs:30:9
+  --> $DIR/shadow.rs:31:9
    |
 LL |     let x = id(x);
    |         ^
 
 error: `x` is shadowed by `first(x)` which reuses the original value
-  --> $DIR/shadow.rs:32:9
+  --> $DIR/shadow.rs:33:9
    |
 LL |     let x = first(x);
    |         ^
    |
 note: initialization happens here
-  --> $DIR/shadow.rs:32:13
+  --> $DIR/shadow.rs:33:13
    |
 LL |     let x = first(x);
    |             ^^^^^^^^
 note: previous binding is here
-  --> $DIR/shadow.rs:31:9
+  --> $DIR/shadow.rs:32:9
    |
 LL |     let x = (1, x);
    |         ^
 
 error: `x` is being shadowed
-  --> $DIR/shadow.rs:34:9
+  --> $DIR/shadow.rs:35:9
    |
 LL |     let x = y;
    |         ^
    |
    = note: `-D clippy::shadow-unrelated` implied by `-D warnings`
 note: initialization happens here
-  --> $DIR/shadow.rs:34:13
+  --> $DIR/shadow.rs:35:13
    |
 LL |     let x = y;
    |             ^
 note: previous binding is here
-  --> $DIR/shadow.rs:32:9
+  --> $DIR/shadow.rs:33:9
    |
 LL |     let x = first(x);
    |         ^
 
 error: `x` shadows a previous declaration
-  --> $DIR/shadow.rs:36:5
+  --> $DIR/shadow.rs:37:5
    |
 LL |     let x;
    |     ^^^^^^
    |
 note: previous binding is here
-  --> $DIR/shadow.rs:34:9
+  --> $DIR/shadow.rs:35:9
    |
 LL |     let x = y;
    |         ^
diff --git a/tests/ui/update-references.sh b/tests/ui/update-references.sh
index 2c13c327d79..e16ed600ef8 100755
--- a/tests/ui/update-references.sh
+++ b/tests/ui/update-references.sh
@@ -30,15 +30,27 @@ while [[ "$1" != "" ]]; do
            ! (cmp -s -- "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"); then
         echo updating "$MYDIR"/"$STDOUT_NAME"
         cp "$BUILD_DIR"/"$STDOUT_NAME" "$MYDIR"/"$STDOUT_NAME"
+        if [[ ! -s "$MYDIR"/"$STDOUT_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDOUT_NAME"
+            rm "$MYDIR"/"$STDOUT_NAME"
+        fi
     fi
     if [[ -f "$BUILD_DIR"/"$STDERR_NAME" ]] && \
            ! (cmp -s -- "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"); then
         echo updating "$MYDIR"/"$STDERR_NAME"
         cp "$BUILD_DIR"/"$STDERR_NAME" "$MYDIR"/"$STDERR_NAME"
+        if [[ ! -s "$MYDIR"/"$STDERR_NAME" ]]; then
+            echo removing "$MYDIR"/"$STDERR_NAME"
+            rm "$MYDIR"/"$STDERR_NAME"
+        fi
     fi
     if [[ -f "$BUILD_DIR"/"$FIXED_NAME" ]] && \
            ! (cmp -s -- "$BUILD_DIR"/"$FIXED_NAME" "$MYDIR"/"$FIXED_NAME"); then
         echo updating "$MYDIR"/"$FIXED_NAME"
         cp "$BUILD_DIR"/"$FIXED_NAME" "$MYDIR"/"$FIXED_NAME"
+        if [[ ! -s "$MYDIR"/"$FIXED_NAME" ]]; then
+            echo removing "$MYDIR"/"$FIXED_NAME"
+            rm "$MYDIR"/"$FIXED_NAME"
+        fi
     fi
 done
diff --git a/tests/ui/used_underscore_binding.rs b/tests/ui/used_underscore_binding.rs
index 8e0243c49aa..d8bda7e8f48 100644
--- a/tests/ui/used_underscore_binding.rs
+++ b/tests/ui/used_underscore_binding.rs
@@ -3,7 +3,7 @@
 
 #![feature(rustc_private)]
 #![warn(clippy::all)]
-#![allow(clippy::blacklisted_name)]
+#![allow(clippy::blacklisted_name, clippy::eq_op)]
 #![warn(clippy::used_underscore_binding)]
 
 #[macro_use]