Auto merge of #87954 - flip1995:clippyup, r=Manishearth

Update Clippy

r? `@Manishearth`

src/tools/clippy/.github/ISSUE_TEMPLATE/new_lint.md

@@ -15,8 +15,9 @@ labels: A-lint
 *What is the advantage of the recommended code over the original code*
 
 For example:
-- Remove bounce checking inserted by ...
+- Remove bounds check inserted by ...
-- Remove the need to duplicating/storing/typo ...
+- Remove the need to duplicate/store ...
+- Remove typo ...
 
 ### Drawbacks
 

src/tools/clippy/.github/workflows/clippy.yml

@@ -49,13 +49,13 @@ jobs:
         echo "LD_LIBRARY_PATH=${SYSROOT}/lib${LD_LIBRARY_PATH+:${LD_LIBRARY_PATH}}" >> $GITHUB_ENV
 
     - name: Build
-      run: cargo build --features deny-warnings,internal-lints
+      run: cargo build --features deny-warnings,internal-lints,metadata-collector-lint
 
     - name: Test
-      run: cargo test --features deny-warnings,internal-lints
+      run: cargo test --features deny-warnings,internal-lints,metadata-collector-lint
 
     - name: Test clippy_lints
-      run: cargo test --features deny-warnings,internal-lints
+      run: cargo test --features deny-warnings,internal-lints,metadata-collector-lint
       working-directory: clippy_lints
 
     - name: Test rustc_tools_util

src/tools/clippy/.github/workflows/clippy_bors.yml

@@ -112,13 +112,13 @@ jobs:
         echo "$SYSROOT/bin" >> $GITHUB_PATH
 
     - name: Build
-      run: cargo build --features deny-warnings,internal-lints
+      run: cargo build --features deny-warnings,internal-lints,metadata-collector-lint
 
     - name: Test
-      run: cargo test --features deny-warnings,internal-lints
+      run: cargo test --features deny-warnings,internal-lints,metadata-collector-lint
 
     - name: Test clippy_lints
-      run: cargo test --features deny-warnings,internal-lints
+      run: cargo test --features deny-warnings,internal-lints,metadata-collector-lint
       working-directory: clippy_lints
 
     - name: Test rustc_tools_util

src/tools/clippy/.github/workflows/remark.yml

@@ -20,6 +20,8 @@ jobs:
 
     - name: Setup Node.js
       uses: actions/setup-node@v1.4.4
+      with:
+        node-version: '12.x'
 
     - name: Install remark
       run: npm install remark-cli remark-lint remark-lint-maximum-line-length remark-preset-lint-recommended remark-gfm

src/tools/clippy/CHANGELOG.md

@@ -6,11 +6,141 @@ document.
 
 ## Unreleased / In Rust Nightly
 
-[3ae8faf...master](https://github.com/rust-lang/rust-clippy/compare/3ae8faf...master)
+[74d1561...master](https://github.com/rust-lang/rust-clippy/compare/74d1561...master)
+
+## Rust 1.55
+
+Current beta, release 2021-09-09
+
+[3ae8faf...74d1561](https://github.com/rust-lang/rust-clippy/compare/3ae8faf...74d1561)
+
+### Important Changes
+
+* Stabilized `cargo clippy --fix` :tada:
+  [#7405](https://github.com/rust-lang/rust-clippy/pull/7405)
+
+### New Lints
+
+* [`rc_mutex`]
+  [#7316](https://github.com/rust-lang/rust-clippy/pull/7316)
+* [`nonstandard_macro_braces`]
+  [#7299](https://github.com/rust-lang/rust-clippy/pull/7299)
+* [`strlen_on_c_strings`]
+  [#7243](https://github.com/rust-lang/rust-clippy/pull/7243)
+* [`self_named_constructors`]
+  [#7403](https://github.com/rust-lang/rust-clippy/pull/7403)
+* [`disallowed_script_idents`]
+  [#7400](https://github.com/rust-lang/rust-clippy/pull/7400)
+* [`disallowed_type`]
+  [#7315](https://github.com/rust-lang/rust-clippy/pull/7315)
+* [`missing_enforced_import_renames`]
+  [#7300](https://github.com/rust-lang/rust-clippy/pull/7300)
+* [`extend_with_drain`]
+  [#7270](https://github.com/rust-lang/rust-clippy/pull/7270)
+
+### Moves and Deprecations
+
+* Moved [`from_iter_instead_of_collect`] to `pedantic`
+  [#7375](https://github.com/rust-lang/rust-clippy/pull/7375)
+* Added `suspicious` as a new lint group for *code that is most likely wrong or useless*
+  [#7350](https://github.com/rust-lang/rust-clippy/pull/7350)
+  * Moved [`blanket_clippy_restriction_lints`] to `suspicious`
+  * Moved [`empty_loop`] to `suspicious`
+  * Moved [`eval_order_dependence`] to `suspicious`
+  * Moved [`float_equality_without_abs`] to `suspicious`
+  * Moved [`for_loops_over_fallibles`] to `suspicious`
+  * Moved [`misrefactored_assign_op`] to `suspicious`
+  * Moved [`mut_range_bound`] to `suspicious`
+  * Moved [`mutable_key_type`] to `suspicious`
+  * Moved [`suspicious_arithmetic_impl`] to `suspicious`
+  * Moved [`suspicious_assignment_formatting`] to `suspicious`
+  * Moved [`suspicious_else_formatting`] to `suspicious`
+  * Moved [`suspicious_map`] to `suspicious`
+  * Moved [`suspicious_op_assign_impl`] to `suspicious`
+  * Moved [`suspicious_unary_op_formatting`] to `suspicious`
+
+### Enhancements
+
+* [`while_let_on_iterator`]: Now suggests `&mut iter` inside closures
+  [#7262](https://github.com/rust-lang/rust-clippy/pull/7262)
+* [`doc_markdown`]:
+  * Now detects unbalanced ticks
+    [#7357](https://github.com/rust-lang/rust-clippy/pull/7357)
+  * Add `FreeBSD` to the default configuration as an allowed identifier
+    [#7334](https://github.com/rust-lang/rust-clippy/pull/7334)
+* [`wildcard_enum_match_arm`], [`match_wildcard_for_single_variants`]: Now allows wildcards for enums with unstable
+  or hidden variants
+  [#7407](https://github.com/rust-lang/rust-clippy/pull/7407)
+* [`redundant_allocation`]: Now additionally supports the `Arc<>` type
+  [#7308](https://github.com/rust-lang/rust-clippy/pull/7308)
+* [`blacklisted_name`]: Now allows blacklisted names in test code
+  [#7379](https://github.com/rust-lang/rust-clippy/pull/7379)
+* [`redundant_closure`]: Suggests `&mut` for `FnMut`
+  [#7437](https://github.com/rust-lang/rust-clippy/pull/7437)
+* [`disallowed_method`], [`disallowed_type`]: The configuration values `disallowed-method` and `disallowed-type`
+  no longer require fully qualified paths
+  [#7345](https://github.com/rust-lang/rust-clippy/pull/7345)
+* [`zst_offset`]: Fixed lint invocation after it was accidentally suppressed
+  [#7396](https://github.com/rust-lang/rust-clippy/pull/7396)
+
+### False Positive Fixes
+
+* [`default_numeric_fallback`]: No longer lints on float literals as function arguments
+  [#7446](https://github.com/rust-lang/rust-clippy/pull/7446)
+* [`use_self`]: No longer lints on type parameters
+  [#7288](https://github.com/rust-lang/rust-clippy/pull/7288)
+* [`unimplemented`]: Now ignores the `assert` and `debug_assert` macros
+  [#7439](https://github.com/rust-lang/rust-clippy/pull/7439)
+* [`branches_sharing_code`]: Now always checks for block expressions
+  [#7462](https://github.com/rust-lang/rust-clippy/pull/7462)
+* [`field_reassign_with_default`]: No longer triggers in macros
+  [#7160](https://github.com/rust-lang/rust-clippy/pull/7160)
+* [`redundant_clone`]: No longer lints on required clones for borrowed data
+  [#7346](https://github.com/rust-lang/rust-clippy/pull/7346)
+* [`default_numeric_fallback`]: No longer triggers in external macros
+  [#7325](https://github.com/rust-lang/rust-clippy/pull/7325)
+* [`needless_bool`]: No longer lints in macros
+  [#7442](https://github.com/rust-lang/rust-clippy/pull/7442)
+* [`useless_format`]: No longer triggers when additional text is being appended
+  [#7442](https://github.com/rust-lang/rust-clippy/pull/7442)
+* [`assertions_on_constants`]: `cfg!(...)` is no longer considered to be a constant
+  [#7319](https://github.com/rust-lang/rust-clippy/pull/7319)
+
+### Suggestion Fixes/Improvements
+
+* [`needless_collect`]: Now show correct lint messages for shadowed values
+  [#7289](https://github.com/rust-lang/rust-clippy/pull/7289)
+* [`wrong_pub_self_convention`]: The deprecated message now suggest the correct configuration value
+  [#7382](https://github.com/rust-lang/rust-clippy/pull/7382)
+* [`semicolon_if_nothing_returned`]: Allow missing semicolon in blocks with only one expression
+  [#7326](https://github.com/rust-lang/rust-clippy/pull/7326)
+
+### ICE Fixes
+
+* [`zero_sized_map_values`]
+  [#7470](https://github.com/rust-lang/rust-clippy/pull/7470)
+* [`redundant_pattern_matching`]
+  [#7471](https://github.com/rust-lang/rust-clippy/pull/7471)
+* [`modulo_one`]
+  [#7473](https://github.com/rust-lang/rust-clippy/pull/7473)
+* [`use_self`]
+  [#7428](https://github.com/rust-lang/rust-clippy/pull/7428)
+
+### Documentation Improvements
+
+* Reworked Clippy's website:
+  [#7279](https://github.com/rust-lang/rust-clippy/pull/7279)
+  [#7172](https://github.com/rust-lang/rust-clippy/issues/7172)
+  * Added applicability information about lints
+  * Added a link to jump into the implementation
+  * Improved loading times
+  * Adapted some styling
+* Clippy now uses a lint to generate its documentation
+  [#7298](https://github.com/rust-lang/rust-clippy/pull/7298)
 
 ## Rust 1.54
 
-Current beta, release 2021-07-29
+Current stable, released 2021-07-29
 
 [7c7683c...3ae8faf](https://github.com/rust-lang/rust-clippy/compare/7c7683c...3ae8faf)
 
@@ -29,7 +159,7 @@ Current beta, release 2021-07-29
 ### Moves and Deprecations
 
 - Deprecate `pub_enum_variant_names` and `wrong_pub_self_convention` in favor of
-  the new `avoid_breaking_exported_api` config option (see
+  the new `avoid-breaking-exported-api` config option (see
   [Enhancements](#1-54-enhancements))
   [#7187](https://github.com/rust-lang/rust-clippy/pull/7187)
 - Move [`inconsistent_struct_constructor`] to `pedantic`
@@ -51,7 +181,7 @@ Current beta, release 2021-07-29
   [#7163](https://github.com/rust-lang/rust-clippy/pull/7163)
 - [`if_then_some_else_none`]: Now works with the MSRV config
   [#7177](https://github.com/rust-lang/rust-clippy/pull/7177)
-- Add `avoid_breaking_exported_api` config option for the lints
+- Add `avoid-breaking-exported-api` config option for the lints
   [`enum_variant_names`], [`large_types_passed_by_value`],
   [`trivially_copy_pass_by_ref`], [`unnecessary_wraps`],
   [`upper_case_acronyms`], and [`wrong_self_convention`]. We recommend to set
@@ -138,7 +268,7 @@ Current beta, release 2021-07-29
 
 ## Rust 1.53
 
-Current stable, released 2021-06-17
+Released 2021-06-17
 
 [6ed6f1e...7c7683c](https://github.com/rust-lang/rust-clippy/compare/6ed6f1e...7c7683c)
 
@@ -2869,6 +2999,7 @@ Released 2018-09-13
 [`unused_unit`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_unit
 [`unusual_byte_groupings`]: https://rust-lang.github.io/rust-clippy/master/index.html#unusual_byte_groupings
 [`unwrap_in_result`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_in_result
+[`unwrap_or_else_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_or_else_default
 [`unwrap_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_used
 [`upper_case_acronyms`]: https://rust-lang.github.io/rust-clippy/master/index.html#upper_case_acronyms
 [`use_debug`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_debug

src/tools/clippy/clippy_lints/src/as_conversions.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_help;
 use rustc_ast::ast::{Expr, ExprKind};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -47,7 +47,7 @@ declare_lint_pass!(AsConversions => [AS_CONVERSIONS]);
 
 impl EarlyLintPass for AsConversions {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if in_external_macro(cx.sess, expr.span) {
             return;
         }
 

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

@@ -230,15 +230,7 @@ impl<'tcx> LateLintPass<'tcx> for DocMarkdown {
                         panic_span: None,
                     };
                     fpu.visit_expr(&body.value);
-                    lint_for_missing_headers(
+                    lint_for_missing_headers(cx, item.def_id, item.span, sig, headers, Some(body_id), fpu.panic_span);
-                        cx,
-                        item.def_id,
-                        item.span,
-                        sig,
-                        headers,
-                        Some(body_id),
-                        fpu.panic_span,
-                    );
                 }
             },
             hir::ItemKind::Impl(ref impl_) => {
@@ -278,15 +270,7 @@ impl<'tcx> LateLintPass<'tcx> for DocMarkdown {
                 panic_span: None,
             };
             fpu.visit_expr(&body.value);
-            lint_for_missing_headers(
+            lint_for_missing_headers(cx, item.def_id, item.span, sig, headers, Some(body_id), fpu.panic_span);
-                cx,
-                item.def_id,
-                item.span,
-                sig,
-                headers,
-                Some(body_id),
-                fpu.panic_span,
-            );
         }
     }
 }

src/tools/clippy/clippy_lints/src/else_if_without_else.rs

@@ -2,7 +2,7 @@
 
 use clippy_utils::diagnostics::span_lint_and_help;
 use rustc_ast::ast::{Expr, ExprKind};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -49,7 +49,7 @@ declare_lint_pass!(ElseIfWithoutElse => [ELSE_IF_WITHOUT_ELSE]);
 
 impl EarlyLintPass for ElseIfWithoutElse {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, mut item: &Expr) {
-        if in_external_macro(cx.sess(), item.span) {
+        if in_external_macro(cx.sess, item.span) {
             return;
         }
 

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

@@ -251,7 +251,7 @@ impl<'tcx> LateLintPass<'tcx> for Functions {
         hir_id: hir::HirId,
     ) {
         too_many_arguments::check_fn(cx, kind, decl, span, hir_id, self.too_many_arguments_threshold);
-        too_many_lines::check_fn(cx, span, body, self.too_many_lines_threshold);
+        too_many_lines::check_fn(cx, kind, span, body, self.too_many_lines_threshold);
         not_unsafe_ptr_arg_deref::check_fn(cx, kind, decl, body, hir_id);
     }
 

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

@@ -1,4 +1,5 @@
 use rustc_hir as hir;
+use rustc_hir::intravisit::FnKind;
 use rustc_lint::{LateContext, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_span::Span;
@@ -8,8 +9,16 @@ use clippy_utils::source::snippet_opt;
 
 use super::TOO_MANY_LINES;
 
-pub(super) fn check_fn(cx: &LateContext<'_>, span: Span, body: &'tcx hir::Body<'_>, too_many_lines_threshold: u64) {
+pub(super) fn check_fn(
-    if in_external_macro(cx.sess(), span) {
+    cx: &LateContext<'_>,
+    kind: FnKind<'tcx>,
+    span: Span,
+    body: &'tcx hir::Body<'_>,
+    too_many_lines_threshold: u64,
+) {
+    // Closures must be contained in a parent body, which will be checked for `too_many_lines`.
+    // Don't check closures for `too_many_lines` to avoid duplicated lints.
+    if matches!(kind, FnKind::Closure) || in_external_macro(cx.sess(), span) {
         return;
     }
 

src/tools/clippy/clippy_lints/src/if_not_else.rs

@@ -3,7 +3,7 @@
 
 use clippy_utils::diagnostics::span_lint_and_help;
 use rustc_ast::ast::{BinOpKind, Expr, ExprKind, UnOp};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -48,7 +48,7 @@ declare_lint_pass!(IfNotElse => [IF_NOT_ELSE]);
 
 impl EarlyLintPass for IfNotElse {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, item: &Expr) {
-        if in_external_macro(cx.sess(), item.span) {
+        if in_external_macro(cx.sess, item.span) {
             return;
         }
         if let ExprKind::If(ref cond, _, Some(ref els)) = item.kind {

src/tools/clippy/clippy_lints/src/items_after_statements.rs

@@ -2,7 +2,7 @@
 
 use clippy_utils::diagnostics::span_lint;
 use rustc_ast::ast::{Block, ItemKind, StmtKind};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -54,7 +54,7 @@ declare_lint_pass!(ItemsAfterStatements => [ITEMS_AFTER_STATEMENTS]);
 
 impl EarlyLintPass for ItemsAfterStatements {
     fn check_block(&mut self, cx: &EarlyContext<'_>, item: &Block) {
-        if in_external_macro(cx.sess(), item.span) {
+        if in_external_macro(cx.sess, item.span) {
             return;
         }
 
@@ -68,7 +68,7 @@ impl EarlyLintPass for ItemsAfterStatements {
         // lint on all further items
         for stmt in stmts {
             if let StmtKind::Item(ref it) = *stmt {
-                if in_external_macro(cx.sess(), it.span) {
+                if in_external_macro(cx.sess, it.span) {
                     return;
                 }
                 if let ItemKind::MacroDef(..) = it.kind {

src/tools/clippy/clippy_lints/src/len_zero.rs

@@ -207,8 +207,7 @@ fn check_trait_items(cx: &LateContext<'_>, visited_trait: &Item<'_>, trait_items
         }
     }
 
-    if cx.access_levels.is_exported(visited_trait.def_id)
+    if cx.access_levels.is_exported(visited_trait.def_id) && trait_items.iter().any(|i| is_named_self(cx, i, sym::len))
-        && trait_items.iter().any(|i| is_named_self(cx, i, sym::len))
     {
         let mut current_and_super_traits = DefIdSet::default();
         fill_trait_set(visited_trait.def_id.to_def_id(), &mut current_and_super_traits, cx);
@@ -331,17 +330,15 @@ fn check_for_is_empty(
             None,
             None,
         ),
-        Some(is_empty) if !cx.access_levels.is_exported(is_empty.def_id.expect_local()) => {
+        Some(is_empty) if !cx.access_levels.is_exported(is_empty.def_id.expect_local()) => (
-            (
+            format!(
-                format!(
+                "{} `{}` has a public `len` method, but a private `is_empty` method",
-                    "{} `{}` has a public `len` method, but a private `is_empty` method",
+                item_kind,
-                    item_kind,
+                item_name.as_str(),
-                    item_name.as_str(),
+            ),
-                ),
+            Some(cx.tcx.def_span(is_empty.def_id)),
-                Some(cx.tcx.def_span(is_empty.def_id)),
+            None,
-                None,
+        ),
-            )
-        },
         Some(is_empty)
             if !(is_empty.fn_has_self_parameter
                 && check_is_empty_sig(cx.tcx.fn_sig(is_empty.def_id).skip_binder(), self_kind, output)) =>

src/tools/clippy/clippy_lints/src/lib.rs

@@ -797,6 +797,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         methods::UNNECESSARY_FILTER_MAP,
         methods::UNNECESSARY_FOLD,
         methods::UNNECESSARY_LAZY_EVALUATIONS,
+        methods::UNWRAP_OR_ELSE_DEFAULT,
         methods::UNWRAP_USED,
         methods::USELESS_ASREF,
         methods::WRONG_SELF_CONVENTION,
@@ -1341,6 +1342,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::UNNECESSARY_FILTER_MAP),
         LintId::of(methods::UNNECESSARY_FOLD),
         LintId::of(methods::UNNECESSARY_LAZY_EVALUATIONS),
+        LintId::of(methods::UNWRAP_OR_ELSE_DEFAULT),
         LintId::of(methods::USELESS_ASREF),
         LintId::of(methods::WRONG_SELF_CONVENTION),
         LintId::of(methods::ZST_OFFSET),
@@ -1535,6 +1537,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::STRING_EXTEND_CHARS),
         LintId::of(methods::UNNECESSARY_FOLD),
         LintId::of(methods::UNNECESSARY_LAZY_EVALUATIONS),
+        LintId::of(methods::UNWRAP_OR_ELSE_DEFAULT),
         LintId::of(methods::WRONG_SELF_CONVENTION),
         LintId::of(misc::TOPLEVEL_REF_ARG),
         LintId::of(misc::ZERO_PTR),

src/tools/clippy/clippy_lints/src/literal_representation.rs

@@ -10,7 +10,7 @@ use clippy_utils::{
 use if_chain::if_chain;
 use rustc_ast::ast::{Expr, ExprKind, Lit, LitKind};
 use rustc_errors::Applicability;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use std::iter;
@@ -222,7 +222,7 @@ impl_lint_pass!(LiteralDigitGrouping => [
 
 impl EarlyLintPass for LiteralDigitGrouping {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if in_external_macro(cx.sess, expr.span) {
             return;
         }
 
@@ -415,7 +415,7 @@ impl_lint_pass!(DecimalLiteralRepresentation => [DECIMAL_LITERAL_REPRESENTATION]
 
 impl EarlyLintPass for DecimalLiteralRepresentation {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if in_external_macro(cx.sess, expr.span) {
             return;
         }
 

src/tools/clippy/clippy_lints/src/loops/never_loop.rs

@@ -1,13 +1,36 @@
+use super::utils::make_iterator_snippet;
 use super::NEVER_LOOP;
-use clippy_utils::diagnostics::span_lint;
+use clippy_utils::diagnostics::span_lint_and_then;
-use rustc_hir::{Block, Expr, ExprKind, HirId, InlineAsmOperand, Stmt, StmtKind};
+use clippy_utils::higher;
+use clippy_utils::source::snippet;
+use rustc_errors::Applicability;
+use rustc_hir::{Block, Expr, ExprKind, HirId, InlineAsmOperand, LoopSource, Node, Pat, Stmt, StmtKind};
 use rustc_lint::LateContext;
 use std::iter::{once, Iterator};
 
 pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-    if let ExprKind::Loop(block, _, _, _) = expr.kind {
+    if let ExprKind::Loop(block, _, source, _) = expr.kind {
         match never_loop_block(block, expr.hir_id) {
-            NeverLoopResult::AlwaysBreak => span_lint(cx, NEVER_LOOP, expr.span, "this loop never actually loops"),
+            NeverLoopResult::AlwaysBreak => {
+                span_lint_and_then(cx, NEVER_LOOP, expr.span, "this loop never actually loops", |diag| {
+                    if_chain! {
+                        if let LoopSource::ForLoop = source;
+                        if let Some((_, Node::Expr(parent_match))) = cx.tcx.hir().parent_iter(expr.hir_id).nth(1);
+                        if let Some((pat, iterator, _, for_span)) = higher::for_loop(parent_match);
+                        then {
+                            // Suggests using an `if let` instead. This is `Unspecified` because the
+                            // loop may (probably) contain `break` statements which would be invalid
+                            // in an `if let`.
+                            diag.span_suggestion_verbose(
+                                for_span.with_hi(iterator.span.hi()),
+                                "if you need the first element of the iterator, try writing",
+                                for_to_if_let_sugg(cx, iterator, pat),
+                                Applicability::Unspecified,
+                            );
+                        }
+                    };
+                });
+            },
             NeverLoopResult::MayContinueMainLoop | NeverLoopResult::Otherwise => (),
         }
     }
@@ -170,3 +193,14 @@ fn never_loop_expr_branch<'a, T: Iterator<Item = &'a Expr<'a>>>(e: &mut T, main_
     e.map(|e| never_loop_expr(e, main_loop_id))
         .fold(NeverLoopResult::AlwaysBreak, combine_branches)
 }
+
+fn for_to_if_let_sugg(cx: &LateContext<'_>, iterator: &Expr<'_>, pat: &Pat<'_>) -> String {
+    let pat_snippet = snippet(cx, pat.span, "_");
+    let iter_snippet = make_iterator_snippet(cx, iterator, &mut Applicability::Unspecified);
+
+    format!(
+        "if let Some({pat}) = {iter}.next()",
+        pat = pat_snippet,
+        iter = iter_snippet
+    )
+}

src/tools/clippy/clippy_lints/src/loops/while_let_on_iterator.rs

@@ -7,7 +7,7 @@ use clippy_utils::{
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor};
-use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, MatchSource, Node, PatKind, QPath, UnOp};
+use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, MatchSource, Mutability, Node, PatKind, QPath, UnOp};
 use rustc_lint::LateContext;
 use rustc_span::{symbol::sym, Span, Symbol};
 
@@ -48,7 +48,12 @@ pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
     // borrowed mutably. TODO: If the struct can be partially moved from and the struct isn't used
     // afterwards a mutable borrow of a field isn't necessary.
     let ref_mut = if !iter_expr.fields.is_empty() || needs_mutable_borrow(cx, &iter_expr, loop_expr) {
-        "&mut "
+        if cx.typeck_results().node_type(iter_expr.hir_id).ref_mutability() == Some(Mutability::Mut) {
+            // Reborrow for mutable references. It may not be possible to get a mutable reference here.
+            "&mut *"
+        } else {
+            "&mut "
+        }
     } else {
         ""
     };
@@ -69,6 +74,8 @@ pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 struct IterExpr {
     /// The span of the whole expression, not just the path and fields stored here.
     span: Span,
+    /// The HIR id of the whole expression, not just the path and fields stored here.
+    hir_id: HirId,
     /// The fields used, in order of child to parent.
     fields: Vec<Symbol>,
     /// The path being used.
@@ -78,12 +85,14 @@ struct IterExpr {
 /// the expression might have side effects.
 fn try_parse_iter_expr(cx: &LateContext<'_>, mut e: &Expr<'_>) -> Option<IterExpr> {
     let span = e.span;
+    let hir_id = e.hir_id;
     let mut fields = Vec::new();
     loop {
         match e.kind {
             ExprKind::Path(ref path) => {
                 break Some(IterExpr {
                     span,
+                    hir_id,
                     fields,
                     path: cx.qpath_res(path, e.hir_id),
                 });
@@ -137,7 +146,7 @@ fn is_expr_same_child_or_parent_field(cx: &LateContext<'_>, expr: &Expr<'_>, fie
     match expr.kind {
         ExprKind::Field(base, name) => {
             if let Some((head_field, tail_fields)) = fields.split_first() {
-                if name.name == *head_field && is_expr_same_field(cx, base, fields, path_res) {
+                if name.name == *head_field && is_expr_same_field(cx, base, tail_fields, path_res) {
                     return true;
                 }
                 // Check if the expression is a parent field

src/tools/clippy/clippy_lints/src/methods/extend_with_drain.rs

@@ -16,7 +16,10 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, arg:
         //check source object
         if let ExprKind::MethodCall(src_method, _, [drain_vec, drain_arg], _) = &arg.kind;
         if src_method.ident.as_str() == "drain";
-        if let src_ty = cx.typeck_results().expr_ty(drain_vec).peel_refs();
+        let src_ty = cx.typeck_results().expr_ty(drain_vec);
+        //check if actual src type is mutable for code suggestion
+        let immutable = src_ty.is_mutable_ptr();
+        let src_ty = src_ty.peel_refs();
         if is_type_diagnostic_item(cx, src_ty, sym::vec_type);
         //check drain range
         if let src_ty_range = cx.typeck_results().expr_ty(drain_arg).peel_refs();
@@ -30,8 +33,9 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, arg:
                 "use of `extend` instead of `append` for adding the full range of a second vector",
                 "try this",
                 format!(
-                    "{}.append(&mut {})",
+                    "{}.append({}{})",
                     snippet_with_applicability(cx, recv.span, "..", &mut applicability),
+                    if immutable { "" } else { "&mut " },
                     snippet_with_applicability(cx, drain_vec.span, "..", &mut applicability)
                 ),
                 applicability,

src/tools/clippy/clippy_lints/src/methods/from_iter_instead_of_collect.rs

@@ -1,10 +1,11 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::implements_trait;
 use clippy_utils::{is_expr_path_def_path, paths, sugg};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
-use rustc_lint::{LateContext, LintContext};
+use rustc_lint::LateContext;
 use rustc_middle::ty::Ty;
 use rustc_span::sym;
 
@@ -43,7 +44,7 @@ fn extract_turbofish(cx: &LateContext<'_>, expr: &hir::Expr<'_>, ty: Ty<'tcx>) -
 
     let call_site = expr.span.source_callsite();
     if_chain! {
-        if let Ok(snippet) = cx.sess().source_map().span_to_snippet(call_site);
+        if let Some(snippet) = snippet_opt(cx, call_site);
         let snippet_split = snippet.split("::").collect::<Vec<_>>();
         if let Some((_, elements)) = snippet_split.split_last();
 

src/tools/clippy/clippy_lints/src/methods/map_flatten.rs

@@ -52,18 +52,32 @@ pub(super) fn check<'tcx>(
         );
     }
 
-    // lint if caller of `.map().flatten()` is an Option
+    // lint if caller of `.map().flatten()` is an Option or Result
-    if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::option_type) {
+    let caller_type = match cx.typeck_results().expr_ty(recv).kind() {
-        let func_snippet = snippet(cx, map_arg.span, "..");
+        ty::Adt(adt, _) => {
-        let hint = format!(".and_then({})", func_snippet);
+            if cx.tcx.is_diagnostic_item(sym::option_type, adt.did) {
-        span_lint_and_sugg(
+                "Option"
-            cx,
+            } else if cx.tcx.is_diagnostic_item(sym::result_type, adt.did) {
-            MAP_FLATTEN,
+                "Result"
-            expr.span.with_lo(recv.span.hi()),
+            } else {
-            "called `map(..).flatten()` on an `Option`",
+                return;
-            "try using `and_then` instead",
+            }
-            hint,
+        },
-            Applicability::MachineApplicable,
+        _ => {
-        );
+            return;
-    }
+        },
+    };
+
+    let func_snippet = snippet(cx, map_arg.span, "..");
+    let hint = format!(".and_then({})", func_snippet);
+    let lint_info = format!("called `map(..).flatten()` on an `{}`", caller_type);
+    span_lint_and_sugg(
+        cx,
+        MAP_FLATTEN,
+        expr.span.with_lo(recv.span.hi()),
+        &lint_info,
+        "try using `and_then` instead",
+        hint,
+        Applicability::MachineApplicable,
+    );
 }

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

@@ -56,6 +56,7 @@ mod uninit_assumed_init;
 mod unnecessary_filter_map;
 mod unnecessary_fold;
 mod unnecessary_lazy_eval;
+mod unwrap_or_else_default;
 mod unwrap_used;
 mod useless_asref;
 mod utils;
@@ -310,6 +311,31 @@ declare_clippy_lint! {
     "using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for usages of `_.unwrap_or_else(Default::default)` on `Option` and
+    /// `Result` values.
+    ///
+    /// ### Why is this bad?
+    /// Readability, these can be written as `_.unwrap_or_default`, which is
+    /// simpler and more concise.
+    ///
+    /// ### Examples
+    /// ```rust
+    /// # let x = Some(1);
+    ///
+    /// // Bad
+    /// x.unwrap_or_else(Default::default);
+    /// x.unwrap_or_else(u32::default);
+    ///
+    /// // Good
+    /// x.unwrap_or_default();
+    /// ```
+    pub UNWRAP_OR_ELSE_DEFAULT,
+    style,
+    "using `.unwrap_or_else(Default::default)`, which is more succinctly expressed as `.unwrap_or_default()`"
+}
+
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for usage of `option.map(_).unwrap_or(_)` or `option.map(_).unwrap_or_else(_)` or
@@ -1766,6 +1792,7 @@ impl_lint_pass!(Methods => [
     SHOULD_IMPLEMENT_TRAIT,
     WRONG_SELF_CONVENTION,
     OK_EXPECT,
+    UNWRAP_OR_ELSE_DEFAULT,
     MAP_UNWRAP_OR,
     RESULT_MAP_OR_INTO_OPTION,
     OPTION_MAP_OR_NONE,
@@ -2172,7 +2199,10 @@ fn check_methods<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Optio
             },
             ("unwrap_or_else", [u_arg]) => match method_call!(recv) {
                 Some(("map", [recv, map_arg], _)) if map_unwrap_or::check(cx, expr, recv, map_arg, u_arg, msrv) => {},
-                _ => unnecessary_lazy_eval::check(cx, expr, recv, u_arg, "unwrap_or"),
+                _ => {
+                    unwrap_or_else_default::check(cx, expr, recv, u_arg);
+                    unnecessary_lazy_eval::check(cx, expr, recv, u_arg, "unwrap_or");
+                },
             },
             _ => {},
         }

src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs

@@ -1,7 +1,9 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::eager_or_lazy::is_lazyness_candidate;
+use clippy_utils::is_trait_item;
 use clippy_utils::source::{snippet, snippet_with_applicability, snippet_with_macro_callsite};
-use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, match_type};
+use clippy_utils::ty::implements_trait;
+use clippy_utils::ty::{is_type_diagnostic_item, match_type};
 use clippy_utils::{contains_return, last_path_segment, paths};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
@@ -34,15 +36,23 @@ pub(super) fn check<'tcx>(
         or_has_args: bool,
         span: Span,
     ) -> bool {
+        let is_default_default = || is_trait_item(cx, fun, sym::Default);
+
+        let implements_default = |arg, default_trait_id| {
+            let arg_ty = cx.typeck_results().expr_ty(arg);
+            implements_trait(cx, arg_ty, default_trait_id, &[])
+        };
+
         if_chain! {
             if !or_has_args;
             if name == "unwrap_or";
             if let hir::ExprKind::Path(ref qpath) = fun.kind;
-            let path = last_path_segment(qpath).ident.name;
-            if matches!(path, kw::Default | sym::new);
-            let arg_ty = cx.typeck_results().expr_ty(arg);
             if let Some(default_trait_id) = cx.tcx.get_diagnostic_item(sym::Default);
-            if implements_trait(cx, arg_ty, default_trait_id, &[]);
+            let path = last_path_segment(qpath).ident.name;
+            // needs to target Default::default in particular or be *::new and have a Default impl
+            // available
+            if (matches!(path, kw::Default) && is_default_default())
+                || (matches!(path, sym::new) && implements_default(arg, default_trait_id));
 
             then {
                 let mut applicability = Applicability::MachineApplicable;

src/tools/clippy/clippy_lints/src/methods/unwrap_or_else_default.rs

@@ -0,0 +1,45 @@
+//! Lint for `some_result_or_option.unwrap_or_else(Default::default)`
+
+use super::UNWRAP_OR_ELSE_DEFAULT;
+use clippy_utils::{
+    diagnostics::span_lint_and_sugg, is_trait_item, source::snippet_with_applicability, ty::is_type_diagnostic_item,
+};
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_lint::LateContext;
+use rustc_span::sym;
+
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx hir::Expr<'_>,
+    recv: &'tcx hir::Expr<'_>,
+    u_arg: &'tcx hir::Expr<'_>,
+) {
+    // something.unwrap_or_else(Default::default)
+    // ^^^^^^^^^- recv          ^^^^^^^^^^^^^^^^- u_arg
+    // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- expr
+    let recv_ty = cx.typeck_results().expr_ty(recv);
+    let is_option = is_type_diagnostic_item(cx, recv_ty, sym::option_type);
+    let is_result = is_type_diagnostic_item(cx, recv_ty, sym::result_type);
+
+    if_chain! {
+        if is_option || is_result;
+        if is_trait_item(cx, u_arg, sym::Default);
+        then {
+            let mut applicability = Applicability::MachineApplicable;
+
+            span_lint_and_sugg(
+                cx,
+                UNWRAP_OR_ELSE_DEFAULT,
+                expr.span,
+                "use of `.unwrap_or_else(..)` to construct default value",
+                "try",
+                format!(
+                    "{}.unwrap_or_default()",
+                    snippet_with_applicability(cx, recv.span, "..", &mut applicability)
+                ),
+                applicability,
+            );
+        }
+    }
+}

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

@@ -12,7 +12,7 @@ use clippy_utils::source::snippet_opt;
 use rustc_ast::ast::{Expr, Generics, Lit, LitFloatType, LitIntType, LitKind, NodeId, Pat, PatKind};
 use rustc_ast::visit::FnKind;
 use rustc_data_structures::fx::FxHashMap;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
@@ -307,7 +307,7 @@ impl EarlyLintPass for MiscEarlyLints {
     }
 
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if in_external_macro(cx.sess, expr.span) {
             return;
         }
         double_neg::check(cx, expr);

src/tools/clippy/clippy_lints/src/misc_early/unneeded_field_pattern.rs

@@ -1,6 +1,7 @@
 use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
+use clippy_utils::source::snippet_opt;
 use rustc_ast::ast::{Pat, PatKind};
-use rustc_lint::{EarlyContext, LintContext};
+use rustc_lint::EarlyContext;
 
 use super::UNNEEDED_FIELD_PATTERN;
 
@@ -48,7 +49,7 @@ pub(super) fn check(cx: &EarlyContext<'_>, pat: &Pat) {
                             match field.pat.kind {
                                 PatKind::Wild => {},
                                 _ => {
-                                    if let Ok(n) = cx.sess().source_map().span_to_snippet(field.span) {
+                                    if let Some(n) = snippet_opt(cx, field.span) {
                                         normal.push(n);
                                     }
                                 },

src/tools/clippy/clippy_lints/src/needless_borrow.rs

@@ -27,11 +27,15 @@ declare_clippy_lint! {
     ///
     /// ### Example
     /// ```rust
+    /// fn fun(_a: &i32) {}
+    ///
     /// // Bad
     /// let x: &i32 = &&&&&&5;
+    /// fun(&x);
     ///
     /// // Good
     /// let x: &i32 = &5;
+    /// fun(x);
     /// ```
     pub NEEDLESS_BORROW,
     style,

src/tools/clippy/clippy_lints/src/needless_continue.rs

@@ -422,7 +422,7 @@ fn check_and_warn<'a>(cx: &EarlyContext<'_>, expr: &'a ast::Expr) {
 ///
 /// is transformed to
 ///
-/// ```ignore
+/// ```text
 ///     {
 ///         let x = 5;
 /// ```

src/tools/clippy/clippy_lints/src/needless_for_each.rs

@@ -122,7 +122,7 @@ impl LateLintPass<'_> for NeedlessForEach {
 /// 2. Detect use of `return` in `Loop` in the closure body.
 ///
 /// NOTE: The functionality of this type is similar to
-/// [`crate::utilts::visitors::find_all_ret_expressions`], but we can't use
+/// [`clippy_utils::visitors::find_all_ret_expressions`], but we can't use
 /// `find_all_ret_expressions` instead of this type. The reasons are:
 /// 1. `find_all_ret_expressions` passes the argument of `ExprKind::Ret` to a callback, but what we
 ///    need here is `ExprKind::Ret` itself.

src/tools/clippy/clippy_lints/src/no_effect.rs

@@ -3,7 +3,7 @@ use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::has_drop;
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{BinOpKind, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind, UnsafeSource};
+use rustc_hir::{is_range_literal, BinOpKind, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind, UnsafeSource};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use std::ops::Deref;
@@ -68,12 +68,14 @@ fn has_no_effect(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         ExprKind::Call(callee, args) => {
             if let ExprKind::Path(ref qpath) = callee.kind {
                 let res = cx.qpath_res(qpath, callee.hir_id);
-                match res {
+                let def_matched = matches!(
-                    Res::Def(DefKind::Struct | DefKind::Variant | DefKind::Ctor(..), ..) => {
+                    res,
-                        !has_drop(cx, cx.typeck_results().expr_ty(expr))
+                    Res::Def(DefKind::Struct | DefKind::Variant | DefKind::Ctor(..), ..)
-                            && args.iter().all(|arg| has_no_effect(cx, arg))
+                );
-                    },
+                if def_matched || is_range_literal(expr) {
-                    _ => false,
+                    !has_drop(cx, cx.typeck_results().expr_ty(expr)) && args.iter().all(|arg| has_no_effect(cx, arg))
+                } else {
+                    false
                 }
             } else {
                 false

src/tools/clippy/clippy_lints/src/non_expressive_names.rs

@@ -127,6 +127,7 @@ const ALLOWED_TO_BE_SIMILAR: &[&[&str]] = &[
     &["qpath", "path"],
     &["lit", "lint"],
     &["wparam", "lparam"],
+    &["iter", "item"],
 ];
 
 struct SimilarNamesNameVisitor<'a, 'tcx, 'b>(&'b mut SimilarNamesLocalVisitor<'a, 'tcx>);

src/tools/clippy/clippy_lints/src/nonstandard_macro_braces.rs

@@ -7,6 +7,7 @@ use clippy_utils::{diagnostics::span_lint_and_help, in_macro, is_direct_expn_of,
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_hir::def_id::DefId;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::Span;
@@ -91,13 +92,23 @@ impl EarlyLintPass for MacroBraces {
 }
 
 fn is_offending_macro<'a>(cx: &EarlyContext<'_>, span: Span, mac_braces: &'a MacroBraces) -> Option<MacroInfo<'a>> {
+    let unnested_or_local = || {
+        let nested = in_macro(span.ctxt().outer_expn_data().call_site);
+        !nested
+            || span
+                .macro_backtrace()
+                .last()
+                .map_or(false, |e| e.macro_def_id.map_or(false, DefId::is_local))
+    };
     if_chain! {
+        // Make sure we are only one level deep otherwise there are to many FP's
         if in_macro(span);
         if let Some((name, braces)) = find_matching_macro(span, &mac_braces.macro_braces);
         if let Some(snip) = snippet_opt(cx, span.ctxt().outer_expn_data().call_site);
         // we must check only invocation sites
         // https://github.com/rust-lang/rust-clippy/issues/7422
-        if snip.starts_with(name);
+        if snip.starts_with(&format!("{}!", name));
+        if unnested_or_local();
         // make formatting consistent
         let c = snip.replace(" ", "");
         if !c.starts_with(&format!("{}!{}", name, braces.0));

src/tools/clippy/clippy_lints/src/pass_by_ref_or_value.rs

@@ -2,9 +2,9 @@ use std::cmp;
 use std::iter;
 
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::is_self_ty;
 use clippy_utils::source::snippet;
 use clippy_utils::ty::is_copy;
+use clippy_utils::{is_self, is_self_ty};
 use if_chain::if_chain;
 use rustc_ast::attr;
 use rustc_errors::Applicability;
@@ -170,7 +170,7 @@ impl<'tcx> PassByRefOrValue {
                         if size <= self.ref_min_size;
                         if let hir::TyKind::Rptr(_, MutTy { ty: decl_ty, .. }) = input.kind;
                         then {
-                            let value_type = if is_self_ty(decl_ty) {
+                            let value_type = if fn_body.and_then(|body| body.params.get(index)).map_or(false, is_self) {
                                 "self".into()
                             } else {
                                 snippet(cx, decl_ty.span, "_").into()

src/tools/clippy/clippy_lints/src/redundant_closure_call.rs

@@ -8,7 +8,7 @@ use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::intravisit as hir_visit;
 use rustc_hir::intravisit::Visitor as HirVisitor;
-use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -63,7 +63,7 @@ impl<'ast> ast_visit::Visitor<'ast> for ReturnVisitor {
 
 impl EarlyLintPass for RedundantClosureCall {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if in_external_macro(cx.sess, expr.span) {
             return;
         }
         if_chain! {

src/tools/clippy/clippy_lints/src/reference.rs

@@ -54,7 +54,8 @@ impl EarlyLintPass for DerefAddrOf {
             then {
                 let mut applicability = Applicability::MachineApplicable;
                 let sugg = if e.span.from_expansion() {
-                    if let Ok(macro_source) = cx.sess.source_map().span_to_snippet(e.span) {
+                    #[allow(clippy::option_if_let_else)]
+                    if let Some(macro_source) = snippet_opt(cx, e.span) {
                         // Remove leading whitespace from the given span
                         // e.g: ` $visitor` turns into `$visitor`
                         let trim_leading_whitespaces = |span| {

src/tools/clippy/clippy_lints/src/swap.rs

@@ -1,15 +1,16 @@
-use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::sugg::Sugg;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{differing_macro_contexts, eq_expr_value};
+use clippy_utils::{can_mut_borrow_both, differing_macro_contexts, eq_expr_value};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{Block, Expr, ExprKind, PatKind, QPath, StmtKind};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::sym;
+use rustc_span::source_map::Spanned;
+use rustc_span::{sym, Span};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -70,9 +71,67 @@ impl<'tcx> LateLintPass<'tcx> for Swap {
     fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'_>) {
         check_manual_swap(cx, block);
         check_suspicious_swap(cx, block);
+        check_xor_swap(cx, block);
     }
 }
 
+fn generate_swap_warning(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>, span: Span, is_xor_based: bool) {
+    let mut applicability = Applicability::MachineApplicable;
+
+    if !can_mut_borrow_both(cx, e1, e2) {
+        if let ExprKind::Index(lhs1, idx1) = e1.kind {
+            if let ExprKind::Index(lhs2, idx2) = e2.kind {
+                if eq_expr_value(cx, lhs1, lhs2) {
+                    let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
+
+                    if matches!(ty.kind(), ty::Slice(_))
+                        || matches!(ty.kind(), ty::Array(_, _))
+                        || is_type_diagnostic_item(cx, ty, sym::vec_type)
+                        || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
+                    {
+                        let slice = Sugg::hir_with_applicability(cx, lhs1, "<slice>", &mut applicability);
+                        span_lint_and_sugg(
+                            cx,
+                            MANUAL_SWAP,
+                            span,
+                            &format!("this looks like you are swapping elements of `{}` manually", slice),
+                            "try",
+                            format!(
+                                "{}.swap({}, {})",
+                                slice.maybe_par(),
+                                snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
+                                snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
+                            ),
+                            applicability,
+                        );
+                    }
+                }
+            }
+        }
+        return;
+    }
+
+    let first = Sugg::hir_with_applicability(cx, e1, "..", &mut applicability);
+    let second = Sugg::hir_with_applicability(cx, e2, "..", &mut applicability);
+    span_lint_and_then(
+        cx,
+        MANUAL_SWAP,
+        span,
+        &format!("this looks like you are swapping `{}` and `{}` manually", first, second),
+        |diag| {
+            diag.span_suggestion(
+                span,
+                "try",
+                format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
+                applicability,
+            );
+            if !is_xor_based {
+                diag.note("or maybe you should use `std::mem::replace`?");
+            }
+        },
+    );
+}
+
 /// Implementation of the `MANUAL_SWAP` lint.
 fn check_manual_swap(cx: &LateContext<'_>, block: &Block<'_>) {
     for w in block.stmts.windows(3) {
@@ -96,123 +155,13 @@ fn check_manual_swap(cx: &LateContext<'_>, block: &Block<'_>) {
             if eq_expr_value(cx, tmp_init, lhs1);
             if eq_expr_value(cx, rhs1, lhs2);
             then {
-                if let ExprKind::Field(lhs1, _) = lhs1.kind {
-                    if let ExprKind::Field(lhs2, _) = lhs2.kind {
-                        if lhs1.hir_id.owner == lhs2.hir_id.owner {
-                            return;
-                        }
-                    }
-                }
-
-                let mut applicability = Applicability::MachineApplicable;
-
-                let slice = check_for_slice(cx, lhs1, lhs2);
-                let (replace, what, sugg) = if let Slice::NotSwappable = slice {
-                    return;
-                } else if let Slice::Swappable(slice, idx1, idx2) = slice {
-                    if let Some(slice) = Sugg::hir_opt(cx, slice) {
-                        (
-                            false,
-                            format!(" elements of `{}`", slice),
-                            format!(
-                                "{}.swap({}, {})",
-                                slice.maybe_par(),
-                                snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
-                                snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
-                            ),
-                        )
-                    } else {
-                        (false, String::new(), String::new())
-                    }
-                } else if let (Some(first), Some(second)) = (Sugg::hir_opt(cx, lhs1), Sugg::hir_opt(cx, rhs1)) {
-                    (
-                        true,
-                        format!(" `{}` and `{}`", first, second),
-                        format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
-                    )
-                } else {
-                    (true, String::new(), String::new())
-                };
-
                 let span = w[0].span.to(second.span);
-
+                generate_swap_warning(cx, lhs1, lhs2, span, false);
-                span_lint_and_then(
-                    cx,
-                    MANUAL_SWAP,
-                    span,
-                    &format!("this looks like you are swapping{} manually", what),
-                    |diag| {
-                        if !sugg.is_empty() {
-                            diag.span_suggestion(
-                                span,
-                                "try",
-                                sugg,
-                                applicability,
-                            );
-
-                            if replace {
-                                diag.note("or maybe you should use `std::mem::replace`?");
-                            }
-                        }
-                    }
-                );
             }
         }
     }
 }
 
-enum Slice<'a> {
-    /// `slice.swap(idx1, idx2)` can be used
-    ///
-    /// ## Example
-    ///
-    /// ```rust
-    /// # let mut a = vec![0, 1];
-    /// let t = a[1];
-    /// a[1] = a[0];
-    /// a[0] = t;
-    /// // can be written as
-    /// a.swap(0, 1);
-    /// ```
-    Swappable(&'a Expr<'a>, &'a Expr<'a>, &'a Expr<'a>),
-    /// The `swap` function cannot be used.
-    ///
-    /// ## Example
-    ///
-    /// ```rust
-    /// # let mut a = [vec![1, 2], vec![3, 4]];
-    /// let t = a[0][1];
-    /// a[0][1] = a[1][0];
-    /// a[1][0] = t;
-    /// ```
-    NotSwappable,
-    /// Not a slice
-    None,
-}
-
-/// Checks if both expressions are index operations into "slice-like" types.
-fn check_for_slice<'a>(cx: &LateContext<'_>, lhs1: &'a Expr<'_>, lhs2: &'a Expr<'_>) -> Slice<'a> {
-    if let ExprKind::Index(lhs1, idx1) = lhs1.kind {
-        if let ExprKind::Index(lhs2, idx2) = lhs2.kind {
-            if eq_expr_value(cx, lhs1, lhs2) {
-                let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
-
-                if matches!(ty.kind(), ty::Slice(_))
-                    || matches!(ty.kind(), ty::Array(_, _))
-                    || is_type_diagnostic_item(cx, ty, sym::vec_type)
-                    || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
-                {
-                    return Slice::Swappable(lhs1, idx1, idx2);
-                }
-            } else {
-                return Slice::NotSwappable;
-            }
-        }
-    }
-
-    Slice::None
-}
-
 /// Implementation of the `ALMOST_SWAPPED` lint.
 fn check_suspicious_swap(cx: &LateContext<'_>, block: &Block<'_>) {
     for w in block.stmts.windows(2) {
@@ -262,3 +211,40 @@ fn check_suspicious_swap(cx: &LateContext<'_>, block: &Block<'_>) {
         }
     }
 }
+
+/// Implementation of the xor case for `MANUAL_SWAP` lint.
+fn check_xor_swap(cx: &LateContext<'_>, block: &Block<'_>) {
+    for window in block.stmts.windows(3) {
+        if_chain! {
+            if let Some((lhs0, rhs0)) = extract_sides_of_xor_assign(&window[0]);
+            if let Some((lhs1, rhs1)) = extract_sides_of_xor_assign(&window[1]);
+            if let Some((lhs2, rhs2)) = extract_sides_of_xor_assign(&window[2]);
+            if eq_expr_value(cx, lhs0, rhs1);
+            if eq_expr_value(cx, lhs2, rhs1);
+            if eq_expr_value(cx, lhs1, rhs0);
+            if eq_expr_value(cx, lhs1, rhs2);
+            then {
+                let span = window[0].span.to(window[2].span);
+                generate_swap_warning(cx, lhs0, rhs0, span, true);
+            }
+        };
+    }
+}
+
+/// Returns the lhs and rhs of an xor assignment statement.  
+fn extract_sides_of_xor_assign<'a, 'hir>(stmt: &'a Stmt<'hir>) -> Option<(&'a Expr<'hir>, &'a Expr<'hir>)> {
+    if let StmtKind::Semi(expr) = stmt.kind {
+        if let ExprKind::AssignOp(
+            Spanned {
+                node: BinOpKind::BitXor,
+                ..
+            },
+            lhs,
+            rhs,
+        ) = expr.kind
+        {
+            return Some((lhs, rhs));
+        }
+    }
+    None
+}

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

@@ -186,7 +186,7 @@ declare_clippy_lint! {
     /// Checks for use of redundant allocations anywhere in the code.
     ///
     /// ### Why is this bad?
-    /// Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Arc<T>>`, `Rc<Box<T>>`, Arc<&T>`, `Arc<Rc<T>>`,
+    /// Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Arc<T>>`, `Rc<Box<T>>`, `Arc<&T>`, `Arc<Rc<T>>`,
     /// `Arc<Arc<T>>`, `Arc<Box<T>>`, `Box<&T>`, `Box<Rc<T>>`, `Box<Arc<T>>`, `Box<Box<T>>`, add an unnecessary level of indirection.
     ///
     /// ### Example

src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs

@@ -35,8 +35,6 @@ declare_clippy_lint! {
     /// ```
     /// Use instead:
     /// ```rust
-    /// #![feature(or_patterns)]
-    ///
     /// fn main() {
     ///     if let Some(0 | 2) = Some(0) {}
     /// }

src/tools/clippy/clippy_lints/src/unused_unit.rs

@@ -1,10 +1,10 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::source::position_before_rarrow;
+use clippy_utils::source::{position_before_rarrow, snippet_opt};
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_ast::visit::FnKind;
 use rustc_errors::Applicability;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::BytePos;
@@ -125,17 +125,16 @@ fn is_unit_expr(expr: &ast::Expr) -> bool {
 }
 
 fn lint_unneeded_unit_return(cx: &EarlyContext<'_>, ty: &ast::Ty, span: Span) {
-    let (ret_span, appl) = if let Ok(fn_source) = cx.sess().source_map().span_to_snippet(span.with_hi(ty.span.hi())) {
+    let (ret_span, appl) =
-        position_before_rarrow(&fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
+        snippet_opt(cx, span.with_hi(ty.span.hi())).map_or((ty.span, Applicability::MaybeIncorrect), |fn_source| {
-            (
+            position_before_rarrow(&fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
-                #[allow(clippy::cast_possible_truncation)]
+                (
-                ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
+                    #[allow(clippy::cast_possible_truncation)]
-                Applicability::MachineApplicable,
+                    ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
-            )
+                    Applicability::MachineApplicable,
-        })
+                )
-    } else {
+            })
-        (ty.span, Applicability::MaybeIncorrect)
+        });
-    };
     span_lint_and_sugg(
         cx,
         UNUSED_UNIT,

src/tools/clippy/clippy_lints/src/utils/conf.rs

@@ -36,13 +36,13 @@ impl TryConf {
 /// See (rust-clippy#7172)
 macro_rules! define_Conf {
     ($(
-        #[doc = $doc:literal]
+        $(#[doc = $doc:literal])+
         $(#[conf_deprecated($dep:literal)])?
         ($name:ident: $ty:ty = $default:expr),
     )*) => {
         /// Clippy lint configuration
         pub struct Conf {
-            $(#[doc = $doc] pub $name: $ty,)*
+            $($(#[doc = $doc])+ pub $name: $ty,)*
         }
 
         mod defaults {
@@ -119,7 +119,7 @@ macro_rules! define_Conf {
                                 stringify!($name),
                                 stringify!($ty),
                                 format!("{:?}", super::defaults::$name()),
-                                $doc,
+                                concat!($($doc, '\n',)*),
                                 deprecation_reason,
                             )
                         },
@@ -132,18 +132,30 @@ macro_rules! define_Conf {
 
 // N.B., this macro is parsed by util/lintlib.py
 define_Conf! {
-    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION. Suppress lints whenever the suggested change would cause breakage for other crates.
+    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION.
+    ///
+    /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
-    /// Lint: MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE. The minimum rust version that the project supports
+    /// Lint: MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE.
+    ///
+    /// The minimum rust version that the project supports
     (msrv: Option<String> = None),
-    /// Lint: BLACKLISTED_NAME. The list of blacklisted names to lint about. NB: `bar` is not here since it has legitimate uses
+    /// Lint: BLACKLISTED_NAME.
+    ///
+    /// The list of blacklisted names to lint about. NB: `bar` is not here since it has legitimate uses
     (blacklisted_names: Vec<String> = ["foo", "baz", "quux"].iter().map(ToString::to_string).collect()),
-    /// Lint: COGNITIVE_COMPLEXITY. The maximum cognitive complexity a function can have
+    /// Lint: COGNITIVE_COMPLEXITY.
+    ///
+    /// The maximum cognitive complexity a function can have
     (cognitive_complexity_threshold: u64 = 25),
-    /// DEPRECATED LINT: CYCLOMATIC_COMPLEXITY. Use the Cognitive Complexity lint instead.
+    /// DEPRECATED LINT: CYCLOMATIC_COMPLEXITY.
+    ///
+    /// Use the Cognitive Complexity lint instead.
     #[conf_deprecated("Please use `cognitive-complexity-threshold` instead")]
     (cyclomatic_complexity_threshold: Option<u64> = None),
-    /// Lint: DOC_MARKDOWN. The list of words this lint should not consider as identifiers needing ticks
+    /// Lint: DOC_MARKDOWN.
+    ///
+    /// The list of words this lint should not consider as identifiers needing ticks
     (doc_valid_idents: Vec<String> = [
         "KiB", "MiB", "GiB", "TiB", "PiB", "EiB",
         "DirectX",
@@ -164,55 +176,109 @@ define_Conf! {
         "MinGW",
         "CamelCase",
     ].iter().map(ToString::to_string).collect()),
-    /// Lint: TOO_MANY_ARGUMENTS. The maximum number of argument a function or method can have
+    /// Lint: TOO_MANY_ARGUMENTS.
+    ///
+    /// The maximum number of argument a function or method can have
     (too_many_arguments_threshold: u64 = 7),
-    /// Lint: TYPE_COMPLEXITY. The maximum complexity a type can have
+    /// Lint: TYPE_COMPLEXITY.
+    ///
+    /// The maximum complexity a type can have
     (type_complexity_threshold: u64 = 250),
-    /// Lint: MANY_SINGLE_CHAR_NAMES. The maximum number of single char bindings a scope may have
+    /// Lint: MANY_SINGLE_CHAR_NAMES.
+    ///
+    /// The maximum number of single char bindings a scope may have
     (single_char_binding_names_threshold: u64 = 4),
-    /// Lint: BOXED_LOCAL, USELESS_VEC. The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap
+    /// Lint: BOXED_LOCAL, USELESS_VEC.
+    ///
+    /// The maximum size of objects (in bytes) that will be linted. Larger objects are ok on the heap
     (too_large_for_stack: u64 = 200),
-    /// Lint: ENUM_VARIANT_NAMES. The minimum number of enum variants for the lints about variant names to trigger
+    /// Lint: ENUM_VARIANT_NAMES.
+    ///
+    /// The minimum number of enum variants for the lints about variant names to trigger
     (enum_variant_name_threshold: u64 = 3),
-    /// Lint: LARGE_ENUM_VARIANT. The maximum size of a enum's variant to avoid box suggestion
+    /// Lint: LARGE_ENUM_VARIANT.
+    ///
+    /// The maximum size of a enum's variant to avoid box suggestion
     (enum_variant_size_threshold: u64 = 200),
-    /// Lint: VERBOSE_BIT_MASK. The maximum allowed size of a bit mask before suggesting to use 'trailing_zeros'
+    /// Lint: VERBOSE_BIT_MASK.
+    ///
+    /// The maximum allowed size of a bit mask before suggesting to use 'trailing_zeros'
     (verbose_bit_mask_threshold: u64 = 1),
-    /// Lint: DECIMAL_LITERAL_REPRESENTATION. The lower bound for linting decimal literals
+    /// Lint: DECIMAL_LITERAL_REPRESENTATION.
+    ///
+    /// The lower bound for linting decimal literals
     (literal_representation_threshold: u64 = 16384),
-    /// Lint: TRIVIALLY_COPY_PASS_BY_REF. The maximum size (in bytes) to consider a `Copy` type for passing by value instead of by reference.
+    /// Lint: TRIVIALLY_COPY_PASS_BY_REF.
+    ///
+    /// The maximum size (in bytes) to consider a `Copy` type for passing by value instead of by reference.
     (trivial_copy_size_limit: Option<u64> = None),
-    /// Lint: LARGE_TYPE_PASS_BY_MOVE. The minimum size (in bytes) to consider a type for passing by reference instead of by value.
+    /// Lint: LARGE_TYPE_PASS_BY_MOVE.
+    ///
+    /// The minimum size (in bytes) to consider a type for passing by reference instead of by value.
     (pass_by_value_size_limit: u64 = 256),
-    /// Lint: TOO_MANY_LINES. The maximum number of lines a function or method can have
+    /// Lint: TOO_MANY_LINES.
+    ///
+    /// The maximum number of lines a function or method can have
     (too_many_lines_threshold: u64 = 100),
-    /// Lint: LARGE_STACK_ARRAYS, LARGE_CONST_ARRAYS. The maximum allowed size for arrays on the stack
+    /// Lint: LARGE_STACK_ARRAYS, LARGE_CONST_ARRAYS.
+    ///
+    /// The maximum allowed size for arrays on the stack
     (array_size_threshold: u64 = 512_000),
-    /// Lint: VEC_BOX. The size of the boxed type in bytes, where boxing in a `Vec` is allowed
+    /// Lint: VEC_BOX.
+    ///
+    /// The size of the boxed type in bytes, where boxing in a `Vec` is allowed
     (vec_box_size_threshold: u64 = 4096),
-    /// Lint: TYPE_REPETITION_IN_BOUNDS. The maximum number of bounds a trait can have to be linted
+    /// Lint: TYPE_REPETITION_IN_BOUNDS.
+    ///
+    /// The maximum number of bounds a trait can have to be linted
     (max_trait_bounds: u64 = 3),
-    /// Lint: STRUCT_EXCESSIVE_BOOLS. The maximum number of bool fields a struct can have
+    /// Lint: STRUCT_EXCESSIVE_BOOLS.
+    ///
+    /// The maximum number of bool fields a struct can have
     (max_struct_bools: u64 = 3),
-    /// Lint: FN_PARAMS_EXCESSIVE_BOOLS. The maximum number of bool parameters a function can have
+    /// Lint: FN_PARAMS_EXCESSIVE_BOOLS.
+    ///
+    /// The maximum number of bool parameters a function can have
     (max_fn_params_bools: u64 = 3),
-    /// Lint: WILDCARD_IMPORTS. Whether to allow certain wildcard imports (prelude, super in tests).
+    /// Lint: WILDCARD_IMPORTS.
+    ///
+    /// Whether to allow certain wildcard imports (prelude, super in tests).
     (warn_on_all_wildcard_imports: bool = false),
-    /// Lint: DISALLOWED_METHOD. The list of disallowed methods, written as fully qualified paths.
+    /// Lint: DISALLOWED_METHOD.
+    ///
+    /// The list of disallowed methods, written as fully qualified paths.
     (disallowed_methods: Vec<String> = Vec::new()),
-    /// Lint: DISALLOWED_TYPE. The list of disallowed types, written as fully qualified paths.
+    /// Lint: DISALLOWED_TYPE.
+    ///
+    /// The list of disallowed types, written as fully qualified paths.
     (disallowed_types: Vec<String> = Vec::new()),
-    /// Lint: UNREADABLE_LITERAL. Should the fraction of a decimal be linted to include separators.
+    /// Lint: UNREADABLE_LITERAL.
+    ///
+    /// Should the fraction of a decimal be linted to include separators.
     (unreadable_literal_lint_fractions: bool = true),
-    /// Lint: UPPER_CASE_ACRONYMS. Enables verbose mode. Triggers if there is more than one uppercase char next to each other
+    /// Lint: UPPER_CASE_ACRONYMS.
+    ///
+    /// Enables verbose mode. Triggers if there is more than one uppercase char next to each other
     (upper_case_acronyms_aggressive: bool = false),
-    /// Lint: _CARGO_COMMON_METADATA. For internal testing only, ignores the current `publish` settings in the Cargo manifest.
+    /// Lint: _CARGO_COMMON_METADATA.
+    ///
+    /// For internal testing only, ignores the current `publish` settings in the Cargo manifest.
     (cargo_ignore_publish: bool = false),
-    /// Lint: NONSTANDARD_MACRO_BRACES. Enforce the named macros always use the braces specified. <br> A `MacroMatcher` can be added like so `{ name = "macro_name", brace = "(" }`. If the macro is could be used with a full path two `MacroMatcher`s have to be added one with the full path `crate_name::macro_name` and one with just the macro name.
+    /// Lint: NONSTANDARD_MACRO_BRACES.
+    ///
+    /// Enforce the named macros always use the braces specified.
+    ///
+    /// A `MacroMatcher` can be added like so `{ name = "macro_name", brace = "(" }`. If the macro
+    /// is could be used with a full path two `MacroMatcher`s have to be added one with the full path
+    /// `crate_name::macro_name` and one with just the macro name.
     (standard_macro_braces: Vec<crate::nonstandard_macro_braces::MacroMatcher> = Vec::new()),
-    /// Lint: MISSING_ENFORCED_IMPORT_RENAMES. The list of imports to always rename, a fully qualified path followed by the rename.
+    /// Lint: MISSING_ENFORCED_IMPORT_RENAMES.
+    ///
+    /// The list of imports to always rename, a fully qualified path followed by the rename.
     (enforced_import_renames: Vec<crate::utils::conf::Rename> = Vec::new()),
-    /// Lint: RESTRICTED_SCRIPTS. The list of unicode scripts allowed to be used in the scope.
+    /// Lint: RESTRICTED_SCRIPTS.
+    ///
+    /// The list of unicode scripts allowed to be used in the scope.
     (allowed_scripts: Vec<String> = vec!["Latin".to_string()]),
 }
 

src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -82,7 +82,7 @@ This lint has the following configuration variables:
 /// `default`
 macro_rules! CONFIGURATION_VALUE_TEMPLATE {
     () => {
-        "* {name}: {ty}: {doc} (defaults to `{default}`)\n"
+        "* {name}: `{ty}`: {doc} (defaults to `{default}`)\n"
     };
 }
 
@@ -344,11 +344,16 @@ fn parse_config_field_doc(doc_comment: &str) -> Option<(Vec<String>, String)> {
         if let Some(split_pos) = doc_comment.find('.');
         then {
             let mut doc_comment = doc_comment.to_string();
-            let documentation = doc_comment.split_off(split_pos);
+            let mut documentation = doc_comment.split_off(split_pos);
 
+            // Extract lints
             doc_comment.make_ascii_lowercase();
             let lints: Vec<String> = doc_comment.split_off(DOC_START.len()).split(", ").map(str::to_string).collect();
 
+            // Format documentation correctly
+            // split off leading `.` from lint name list and indent for correct formatting
+            documentation = documentation.trim_start_matches('.').trim().replace("\n ", "\n    ");
+
             Some((lints, documentation))
         } else {
             None

src/tools/clippy/clippy_utils/src/diagnostics.rs

@@ -65,7 +65,7 @@ pub fn span_lint<T: LintContext>(cx: &T, lint: &'static Lint, sp: impl Into<Mult
 ///
 /// # Example
 ///
-/// ```ignore
+/// ```text
 /// error: constant division of 0.0 with 0.0 will always result in NaN
 ///   --> $DIR/zero_div_zero.rs:6:25
 ///    |
@@ -103,7 +103,7 @@ pub fn span_lint_and_help<'a, T: LintContext>(
 ///
 /// # Example
 ///
-/// ```ignore
+/// ```text
 /// error: calls to `std::mem::forget` with a reference instead of an owned value. Forgetting a reference does nothing.
 ///   --> $DIR/drop_forget_ref.rs:10:5
 ///    |
@@ -189,7 +189,7 @@ pub fn span_lint_hir_and_then(
 ///
 /// # Example
 ///
-/// ```ignore
+/// ```text
 /// error: This `.fold` can be more succinctly expressed as `.any`
 /// --> $DIR/methods.rs:390:13
 ///     |

src/tools/clippy/clippy_utils/src/higher.rs

@@ -195,8 +195,8 @@ pub fn vec_macro<'e>(cx: &LateContext<'_>, expr: &'e hir::Expr<'_>) -> Option<Ve
 /// - `assert!`, `assert_eq!` and `assert_ne!`
 /// - `debug_assert!`, `debug_assert_eq!` and `debug_assert_ne!`
 /// For example:
-/// `assert!(expr)` will return Some([expr])
+/// `assert!(expr)` will return `Some([expr])`
-/// `debug_assert_eq!(a, b)` will return Some([a, b])
+/// `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
@@ -283,7 +283,7 @@ pub struct FormatArgsExpn<'tcx> {
 
     /// String literal expressions which represent the format string split by "{}"
     pub format_string_parts: &'tcx [Expr<'tcx>],
-    /// Symbols corresponding to [`format_string_parts`]
+    /// Symbols corresponding to [`Self::format_string_parts`]
     pub format_string_symbols: Vec<Symbol>,
     /// Expressions like `ArgumentV1::new(arg0, Debug::fmt)`
     pub args: &'tcx [Expr<'tcx>],

src/tools/clippy/clippy_utils/src/lib.rs

@@ -326,6 +326,25 @@ pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol)
         .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
 }
 
+/// Checks if the given expression is a path referring an item on the trait
+/// that is marked with the given diagnostic item.
+///
+/// For checking method call expressions instead of path expressions, use
+/// [`is_trait_method`].
+///
+/// For example, this can be used to find if an expression like `u64::default`
+/// refers to an item of the trait `Default`, which is associated with the
+/// `diag_item` of `sym::Default`.
+pub fn is_trait_item(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol) -> bool {
+    if let hir::ExprKind::Path(ref qpath) = expr.kind {
+        cx.qpath_res(qpath, expr.hir_id)
+            .opt_def_id()
+            .map_or(false, |def_id| is_diag_trait_item(cx, def_id, diag_item))
+    } else {
+        false
+    }
+}
+
 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
     match *path {
         QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
@@ -558,6 +577,54 @@ pub fn trait_ref_of_method<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Optio
     None
 }
 
+/// This method will return tuple of projection stack and root of the expression,
+/// used in `can_mut_borrow_both`.
+///
+/// For example, if `e` represents the `v[0].a.b[x]`
+/// this method will return a tuple, composed of a `Vec`
+/// containing the `Expr`s for `v[0], v[0].a, v[0].a.b, v[0].a.b[x]`
+/// and a `Expr` for root of them, `v`
+fn projection_stack<'a, 'hir>(mut e: &'a Expr<'hir>) -> (Vec<&'a Expr<'hir>>, &'a Expr<'hir>) {
+    let mut result = vec![];
+    let root = loop {
+        match e.kind {
+            ExprKind::Index(ep, _) | ExprKind::Field(ep, _) => {
+                result.push(e);
+                e = ep;
+            },
+            _ => break e,
+        };
+    };
+    result.reverse();
+    (result, root)
+}
+
+/// Checks if two expressions can be mutably borrowed simultaneously
+/// and they aren't dependent on borrowing same thing twice
+pub fn can_mut_borrow_both(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>) -> bool {
+    let (s1, r1) = projection_stack(e1);
+    let (s2, r2) = projection_stack(e2);
+    if !eq_expr_value(cx, r1, r2) {
+        return true;
+    }
+    for (x1, x2) in s1.iter().zip(s2.iter()) {
+        match (&x1.kind, &x2.kind) {
+            (ExprKind::Field(_, i1), ExprKind::Field(_, i2)) => {
+                if i1 != i2 {
+                    return true;
+                }
+            },
+            (ExprKind::Index(_, i1), ExprKind::Index(_, i2)) => {
+                if !eq_expr_value(cx, i1, i2) {
+                    return false;
+                }
+            },
+            _ => return false,
+        }
+    }
+    false
+}
+
 /// Checks if the top level expression can be moved into a closure as is.
 pub fn can_move_expr_to_closure_no_visit(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, jump_targets: &[HirId]) -> bool {
     match expr.kind {

src/tools/clippy/clippy_utils/src/source.rs

@@ -168,7 +168,7 @@ pub fn snippet<'a, T: LintContext>(cx: &T, span: Span, default: &'a str) -> Cow<
     snippet_opt(cx, span).map_or_else(|| Cow::Borrowed(default), From::from)
 }
 
-/// Same as `snippet`, but it adapts the applicability level by following rules:
+/// Same as [`snippet`], but it adapts the applicability level by following rules:
 ///
 /// - Applicability level `Unspecified` will never be changed.
 /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.

src/tools/clippy/clippy_utils/src/ty.rs

@@ -114,7 +114,7 @@ pub fn has_iter_method(cx: &LateContext<'_>, probably_ref_ty: Ty<'_>) -> Option<
 
 /// Checks whether a type implements a trait.
 /// The function returns false in case the type contains an inference variable.
-/// See also `get_trait_def_id`.
+/// See also [`get_trait_def_id`](super::get_trait_def_id).
 pub fn implements_trait<'tcx>(
     cx: &LateContext<'tcx>,
     ty: Ty<'tcx>,

src/tools/clippy/doc/basics.md

@@ -166,8 +166,8 @@ rustup component add clippy
 ```
 
 > **DO NOT** install using `cargo install --path . --force` since this will overwrite rustup
-[proxies](https://rust-lang.github.io/rustup/concepts/proxies.html). That is, `~/.cargo/bin/cargo-clippy` and
+> [proxies](https://rust-lang.github.io/rustup/concepts/proxies.html). That is, `~/.cargo/bin/cargo-clippy` and
-`~/.cargo/bin/clippy-driver` should be hard or soft links to `~/.cargo/bin/rustup`. You can repair these by running
+> `~/.cargo/bin/clippy-driver` should be hard or soft links to `~/.cargo/bin/rustup`. You can repair these by running
-`rustup update`.
+> `rustup update`.
 
 [glossary]: https://rustc-dev-guide.rust-lang.org/appendix/glossary.html

src/tools/clippy/rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2021-07-29"
+channel = "nightly-2021-08-12"
 components = ["llvm-tools-preview", "rustc-dev", "rust-src"]

src/tools/clippy/tests/ui-toml/functions_maxlines/test.rs

@@ -1,3 +1,5 @@
+// edition:2018
+
 #![warn(clippy::too_many_lines)]
 
 // This function should be considered one line.
@@ -20,6 +22,20 @@ fn too_many_lines() {
     println!("This is bad.");
 }
 
+// This should only fail once (#7517).
+async fn async_too_many_lines() {
+    println!("This is bad.");
+    println!("This is bad.");
+}
+
+// This should fail only once, without failing on the closure.
+fn closure_too_many_lines() {
+    let _ = {
+        println!("This is bad.");
+        println!("This is bad.");
+    };
+}
+
 // This should be considered one line.
 #[rustfmt::skip]
 fn comment_starts_after_code() {

src/tools/clippy/tests/ui-toml/functions_maxlines/test.stderr

@@ -1,5 +1,5 @@
 error: this function has too many lines (2/1)
-  --> $DIR/test.rs:18:1
+  --> $DIR/test.rs:20:1
    |
 LL | / fn too_many_lines() {
 LL | |     println!("This is bad.");
@@ -9,8 +9,28 @@ LL | | }
    |
    = note: `-D clippy::too-many-lines` implied by `-D warnings`
 
+error: this function has too many lines (4/1)
+  --> $DIR/test.rs:26:1
+   |
+LL | / async fn async_too_many_lines() {
+LL | |     println!("This is bad.");
+LL | |     println!("This is bad.");
+LL | | }
+   | |_^
+
+error: this function has too many lines (4/1)
+  --> $DIR/test.rs:32:1
+   |
+LL | / fn closure_too_many_lines() {
+LL | |     let _ = {
+LL | |         println!("This is bad.");
+LL | |         println!("This is bad.");
+LL | |     };
+LL | | }
+   | |_^
+
 error: this function has too many lines (2/1)
-  --> $DIR/test.rs:38:1
+  --> $DIR/test.rs:54:1
    |
 LL | / fn comment_before_code() {
 LL | |     let _ = "test";
@@ -19,5 +39,5 @@ LL | |     the code but this line should still count. */ let _ = 5;
 LL | | }
    | |_^
 
-error: aborting due to 2 previous errors
+error: aborting due to 4 previous errors
 

src/tools/clippy/tests/ui-toml/nonstandard_macro_braces/conf_nonstandard_macro_braces.rs

@@ -32,13 +32,19 @@ macro_rules! type_pos {
     };
 }
 
+macro_rules! printlnfoo {
+    ($thing:expr) => {
+        println!("{}", $thing)
+    };
+}
+
 #[rustfmt::skip]
 fn main() {
     let _ = vec! {1, 2, 3};
     let _ = format!["ugh {} stop being such a good compiler", "hello"];
     let _ = quote!(let x = 1;);
     let _ = quote::quote!(match match match);
-    let _ = test!();
+    let _ = test!(); // trigger when macro def is inside our own crate
     let _ = vec![1,2,3];
 
     let _ = quote::quote! {true || false};
@@ -49,4 +55,6 @@ fn main() {
     let _: type_pos!(usize) = vec![];
 
     eprint!("test if user config overrides defaults");
+
+    printlnfoo!["test if printlnfoo is triggered by println"];
 }

src/tools/clippy/tests/ui-toml/nonstandard_macro_braces/conf_nonstandard_macro_braces.stderr

@@ -1,48 +1,48 @@
 error: use of irregular braces for `vec!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:37:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:43:13
    |
 LL |     let _ = vec! {1, 2, 3};
    |             ^^^^^^^^^^^^^^
    |
    = note: `-D clippy::nonstandard-macro-braces` implied by `-D warnings`
 help: consider writing `vec![1, 2, 3]`
-  --> $DIR/conf_nonstandard_macro_braces.rs:37:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:43:13
    |
 LL |     let _ = vec! {1, 2, 3};
    |             ^^^^^^^^^^^^^^
 
 error: use of irregular braces for `format!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:38:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:44:13
    |
 LL |     let _ = format!["ugh {} stop being such a good compiler", "hello"];
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: consider writing `format!("ugh () stop being such a good compiler", "hello")`
-  --> $DIR/conf_nonstandard_macro_braces.rs:38:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:44:13
    |
 LL |     let _ = format!["ugh {} stop being such a good compiler", "hello"];
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: use of irregular braces for `quote!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:39:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:45:13
    |
 LL |     let _ = quote!(let x = 1;);
    |             ^^^^^^^^^^^^^^^^^^
    |
 help: consider writing `quote! {let x = 1;}`
-  --> $DIR/conf_nonstandard_macro_braces.rs:39:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:45:13
    |
 LL |     let _ = quote!(let x = 1;);
    |             ^^^^^^^^^^^^^^^^^^
 
 error: use of irregular braces for `quote::quote!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:40:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:46:13
    |
 LL |     let _ = quote::quote!(match match match);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: consider writing `quote::quote! {match match match}`
-  --> $DIR/conf_nonstandard_macro_braces.rs:40:13
+  --> $DIR/conf_nonstandard_macro_braces.rs:46:13
    |
 LL |     let _ = quote::quote!(match match match);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -53,7 +53,7 @@ error: use of irregular braces for `vec!` macro
 LL |         vec!{0, 0, 0}
    |         ^^^^^^^^^^^^^
 ...
-LL |     let _ = test!();
+LL |     let _ = test!(); // trigger when macro def is inside our own crate
    |             ------- in this macro invocation
    |
 help: consider writing `vec![0, 0, 0]`
@@ -62,30 +62,30 @@ help: consider writing `vec![0, 0, 0]`
 LL |         vec!{0, 0, 0}
    |         ^^^^^^^^^^^^^
 ...
-LL |     let _ = test!();
+LL |     let _ = test!(); // trigger when macro def is inside our own crate
    |             ------- in this macro invocation
    = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: use of irregular braces for `type_pos!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:49:12
+  --> $DIR/conf_nonstandard_macro_braces.rs:55:12
    |
 LL |     let _: type_pos!(usize) = vec![];
    |            ^^^^^^^^^^^^^^^^
    |
 help: consider writing `type_pos![usize]`
-  --> $DIR/conf_nonstandard_macro_braces.rs:49:12
+  --> $DIR/conf_nonstandard_macro_braces.rs:55:12
    |
 LL |     let _: type_pos!(usize) = vec![];
    |            ^^^^^^^^^^^^^^^^
 
 error: use of irregular braces for `eprint!` macro
-  --> $DIR/conf_nonstandard_macro_braces.rs:51:5
+  --> $DIR/conf_nonstandard_macro_braces.rs:57:5
    |
 LL |     eprint!("test if user config overrides defaults");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 help: consider writing `eprint!["test if user config overrides defaults"];`
-  --> $DIR/conf_nonstandard_macro_braces.rs:51:5
+  --> $DIR/conf_nonstandard_macro_braces.rs:57:5
    |
 LL |     eprint!("test if user config overrides defaults");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/tools/clippy/tests/ui/extend_with_drain.fixed

@@ -41,7 +41,12 @@ fn main() {
 
     let mut heap = BinaryHeap::from(vec![1, 3]);
     let mut heap2 = BinaryHeap::from(vec![]);
-    heap2.extend(heap.drain())
+    heap2.extend(heap.drain());
+
+    let mut x = vec![0, 1, 2, 3, 5];
+    let ref_x = &mut x;
+    let mut y = Vec::new();
+    y.append(ref_x);
 }
 
 fn return_vector() -> Vec<u8> {

src/tools/clippy/tests/ui/extend_with_drain.rs

@@ -41,7 +41,12 @@ fn main() {
 
     let mut heap = BinaryHeap::from(vec![1, 3]);
     let mut heap2 = BinaryHeap::from(vec![]);
-    heap2.extend(heap.drain())
+    heap2.extend(heap.drain());
+
+    let mut x = vec![0, 1, 2, 3, 5];
+    let ref_x = &mut x;
+    let mut y = Vec::new();
+    y.extend(ref_x.drain(..));
 }
 
 fn return_vector() -> Vec<u8> {

src/tools/clippy/tests/ui/extend_with_drain.stderr

@@ -18,5 +18,11 @@ error: use of `extend` instead of `append` for adding the full range of a second
 LL |     vec11.extend(return_vector().drain(..));
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `vec11.append(&mut return_vector())`
 
-error: aborting due to 3 previous errors
+error: use of `extend` instead of `append` for adding the full range of a second vector
+  --> $DIR/extend_with_drain.rs:49:5
+   |
+LL |     y.extend(ref_x.drain(..));
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `y.append(ref_x)`
+
+error: aborting due to 4 previous errors
 

src/tools/clippy/tests/ui/implicit_hasher.rs

@@ -89,7 +89,7 @@ gen!(fn bar);
 // and should not cause an ICE
 // See #2707
 #[macro_use]
-#[path = "../auxiliary/test_macro.rs"]
+#[path = "auxiliary/test_macro.rs"]
 pub mod test_macro;
 __implicit_hasher_test_macro!(impl<K, V> for HashMap<K, V> where V: test_macro::A);
 

src/tools/clippy/tests/ui/map_flatten.fixed

@@ -5,6 +5,7 @@
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
 #![allow(clippy::unnecessary_wraps)]
+#![feature(result_flattening)]
 
 fn main() {
     // mapping to Option on Iterator
@@ -23,4 +24,7 @@ fn main() {
 
     // mapping to Option on Option
     let _: Option<_> = (Some(Some(1))).and_then(|x| x);
+
+    // mapping to Result on Result
+    let _: Result<_, &str> = (Ok(Ok(1))).and_then(|x| x);
 }

src/tools/clippy/tests/ui/map_flatten.rs

@@ -5,6 +5,7 @@
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
 #![allow(clippy::unnecessary_wraps)]
+#![feature(result_flattening)]
 
 fn main() {
     // mapping to Option on Iterator
@@ -23,4 +24,7 @@ fn main() {
 
     // mapping to Option on Option
     let _: Option<_> = (Some(Some(1))).map(|x| x).flatten();
+
+    // mapping to Result on Result
+    let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten();
 }

src/tools/clippy/tests/ui/map_flatten.stderr

@@ -1,5 +1,5 @@
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:16:46
+  --> $DIR/map_flatten.rs:17:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id)`
@@ -7,34 +7,40 @@ LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().coll
    = note: `-D clippy::map-flatten` implied by `-D warnings`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:17:46
+  --> $DIR/map_flatten.rs:18:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_ref)`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:18:46
+  --> $DIR/map_flatten.rs:19:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_closure)`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:19:46
+  --> $DIR/map_flatten.rs:20:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(|x| x.checked_add(1))`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:22:46
+  --> $DIR/map_flatten.rs:23:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `flat_map` instead: `.flat_map(|x| 0..x)`
 
 error: called `map(..).flatten()` on an `Option`
-  --> $DIR/map_flatten.rs:25:39
+  --> $DIR/map_flatten.rs:26:39
    |
 LL |     let _: Option<_> = (Some(Some(1))).map(|x| x).flatten();
    |                                       ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)`
 
-error: aborting due to 6 previous errors
+error: called `map(..).flatten()` on an `Result`
+  --> $DIR/map_flatten.rs:29:41
+   |
+LL |     let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten();
+   |                                         ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)`
+
+error: aborting due to 7 previous errors
 

src/tools/clippy/tests/ui/never_loop.stderr

@@ -75,6 +75,11 @@ LL | |             _ => return,
 LL | |         }
 LL | |     }
    | |_____^
+   |
+help: if you need the first element of the iterator, try writing
+   |
+LL |     if let Some(x) = (0..10).next() {
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: this loop never actually loops
   --> $DIR/never_loop.rs:157:5

src/tools/clippy/tests/ui/no_effect.stderr

@@ -108,6 +108,12 @@ error: statement with no effect
 LL |     5..6;
    |     ^^^^^
 
+error: statement with no effect
+  --> $DIR/no_effect.rs:83:5
+   |
+LL |     5..=6;
+   |     ^^^^^^
+
 error: statement with no effect
   --> $DIR/no_effect.rs:84:5
    |
@@ -150,5 +156,5 @@ error: statement with no effect
 LL |     FooString { s: s };
    |     ^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 25 previous errors
+error: aborting due to 26 previous errors
 

src/tools/clippy/tests/ui/or_fun_call.fixed

@@ -18,6 +18,19 @@ fn or_fun_call() {
         }
     }
 
+    struct FakeDefault;
+    impl FakeDefault {
+        fn default() -> Self {
+            FakeDefault
+        }
+    }
+
+    impl Default for FakeDefault {
+        fn default() -> Self {
+            FakeDefault
+        }
+    }
+
     enum Enum {
         A(i32),
     }
@@ -53,6 +66,12 @@ fn or_fun_call() {
     let with_default_type = Some(1);
     with_default_type.unwrap_or_default();
 
+    let self_default = None::<FakeDefault>;
+    self_default.unwrap_or_else(<FakeDefault>::default);
+
+    let real_default = None::<FakeDefault>;
+    real_default.unwrap_or_default();
+
     let with_vec = Some(vec![1]);
     with_vec.unwrap_or_default();
 

src/tools/clippy/tests/ui/or_fun_call.rs

@@ -18,6 +18,19 @@ fn or_fun_call() {
         }
     }
 
+    struct FakeDefault;
+    impl FakeDefault {
+        fn default() -> Self {
+            FakeDefault
+        }
+    }
+
+    impl Default for FakeDefault {
+        fn default() -> Self {
+            FakeDefault
+        }
+    }
+
     enum Enum {
         A(i32),
     }
@@ -53,6 +66,12 @@ fn or_fun_call() {
     let with_default_type = Some(1);
     with_default_type.unwrap_or(u64::default());
 
+    let self_default = None::<FakeDefault>;
+    self_default.unwrap_or(<FakeDefault>::default());
+
+    let real_default = None::<FakeDefault>;
+    real_default.unwrap_or(<FakeDefault as Default>::default());
+
     let with_vec = Some(vec![1]);
     with_vec.unwrap_or(vec![]);
 

src/tools/clippy/tests/ui/or_fun_call.stderr

@@ -1,5 +1,5 @@
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:33:19
+  --> $DIR/or_fun_call.rs:46:19
    |
 LL |     with_const_fn.unwrap_or(Duration::from_secs(5));
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| Duration::from_secs(5))`
@@ -7,130 +7,142 @@ LL |     with_const_fn.unwrap_or(Duration::from_secs(5));
    = note: `-D clippy::or-fun-call` implied by `-D warnings`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:36:22
+  --> $DIR/or_fun_call.rs:49:22
    |
 LL |     with_constructor.unwrap_or(make());
    |                      ^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(make)`
 
 error: use of `unwrap_or` followed by a call to `new`
-  --> $DIR/or_fun_call.rs:39:5
+  --> $DIR/or_fun_call.rs:52:5
    |
 LL |     with_new.unwrap_or(Vec::new());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_new.unwrap_or_default()`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:42:21
+  --> $DIR/or_fun_call.rs:55:21
    |
 LL |     with_const_args.unwrap_or(Vec::with_capacity(12));
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| Vec::with_capacity(12))`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:45:14
+  --> $DIR/or_fun_call.rs:58:14
    |
 LL |     with_err.unwrap_or(make());
    |              ^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| make())`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:48:19
+  --> $DIR/or_fun_call.rs:61:19
    |
 LL |     with_err_args.unwrap_or(Vec::with_capacity(12));
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|_| Vec::with_capacity(12))`
 
 error: use of `unwrap_or` followed by a call to `default`
-  --> $DIR/or_fun_call.rs:51:5
+  --> $DIR/or_fun_call.rs:64:5
    |
 LL |     with_default_trait.unwrap_or(Default::default());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_trait.unwrap_or_default()`
 
 error: use of `unwrap_or` followed by a call to `default`
-  --> $DIR/or_fun_call.rs:54:5
+  --> $DIR/or_fun_call.rs:67:5
    |
 LL |     with_default_type.unwrap_or(u64::default());
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_default_type.unwrap_or_default()`
 
+error: use of `unwrap_or` followed by a function call
+  --> $DIR/or_fun_call.rs:70:18
+   |
+LL |     self_default.unwrap_or(<FakeDefault>::default());
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(<FakeDefault>::default)`
+
+error: use of `unwrap_or` followed by a call to `default`
+  --> $DIR/or_fun_call.rs:73:5
+   |
+LL |     real_default.unwrap_or(<FakeDefault as Default>::default());
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `real_default.unwrap_or_default()`
+
 error: use of `unwrap_or` followed by a call to `new`
-  --> $DIR/or_fun_call.rs:57:5
+  --> $DIR/or_fun_call.rs:76:5
    |
 LL |     with_vec.unwrap_or(vec![]);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `with_vec.unwrap_or_default()`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:60:21
+  --> $DIR/or_fun_call.rs:79:21
    |
 LL |     without_default.unwrap_or(Foo::new());
    |                     ^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(Foo::new)`
 
 error: use of `or_insert` followed by a function call
-  --> $DIR/or_fun_call.rs:63:19
+  --> $DIR/or_fun_call.rs:82:19
    |
 LL |     map.entry(42).or_insert(String::new());
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(String::new)`
 
 error: use of `or_insert` followed by a function call
-  --> $DIR/or_fun_call.rs:66:23
+  --> $DIR/or_fun_call.rs:85:23
    |
 LL |     map_vec.entry(42).or_insert(vec![]);
    |                       ^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(Vec::new)`
 
 error: use of `or_insert` followed by a function call
-  --> $DIR/or_fun_call.rs:69:21
+  --> $DIR/or_fun_call.rs:88:21
    |
 LL |     btree.entry(42).or_insert(String::new());
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(String::new)`
 
 error: use of `or_insert` followed by a function call
-  --> $DIR/or_fun_call.rs:72:25
+  --> $DIR/or_fun_call.rs:91:25
    |
 LL |     btree_vec.entry(42).or_insert(vec![]);
    |                         ^^^^^^^^^^^^^^^^^ help: try this: `or_insert_with(Vec::new)`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:75:21
+  --> $DIR/or_fun_call.rs:94:21
    |
 LL |     let _ = stringy.unwrap_or("".to_owned());
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| "".to_owned())`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:83:21
+  --> $DIR/or_fun_call.rs:102:21
    |
 LL |     let _ = Some(1).unwrap_or(map[&1]);
    |                     ^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| map[&1])`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:85:21
+  --> $DIR/or_fun_call.rs:104:21
    |
 LL |     let _ = Some(1).unwrap_or(map[&1]);
    |                     ^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| map[&1])`
 
 error: use of `or` followed by a function call
-  --> $DIR/or_fun_call.rs:109:35
+  --> $DIR/or_fun_call.rs:128:35
    |
 LL |     let _ = Some("a".to_string()).or(Some("b".to_string()));
    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_else(|| Some("b".to_string()))`
 
 error: use of `or` followed by a function call
-  --> $DIR/or_fun_call.rs:113:10
+  --> $DIR/or_fun_call.rs:132:10
    |
 LL |         .or(Some(Bar(b, Duration::from_secs(2))));
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `or_else(|| Some(Bar(b, Duration::from_secs(2))))`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:141:14
+  --> $DIR/or_fun_call.rs:160:14
    |
 LL |         None.unwrap_or(s.as_mut_vec());
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| s.as_mut_vec())`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:146:14
+  --> $DIR/or_fun_call.rs:165:14
    |
 LL |         None.unwrap_or(unsafe { s.as_mut_vec() });
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| unsafe { s.as_mut_vec() })`
 
 error: use of `unwrap_or` followed by a function call
-  --> $DIR/or_fun_call.rs:148:14
+  --> $DIR/or_fun_call.rs:167:14
    |
 LL |         None.unwrap_or( unsafe { s.as_mut_vec() }    );
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `unwrap_or_else(|| unsafe { s.as_mut_vec() })`
 
-error: aborting due to 22 previous errors
+error: aborting due to 24 previous errors
 

src/tools/clippy/tests/ui/similar_names.rs

@@ -76,6 +76,9 @@ fn main() {
     // names often used in win32 code (for example WindowProc)
     let wparam: i32;
     let lparam: i32;
+
+    let iter: i32;
+    let item: i32;
 }
 
 fn foo() {

src/tools/clippy/tests/ui/similar_names.stderr

@@ -72,13 +72,13 @@ LL |     let parser: i32;
    |         ^^^^^^
 
 error: binding's name is too similar to existing binding
-  --> $DIR/similar_names.rs:85:16
+  --> $DIR/similar_names.rs:88:16
    |
 LL |         bpple: sprang,
    |                ^^^^^^
    |
 note: existing binding defined here
-  --> $DIR/similar_names.rs:84:16
+  --> $DIR/similar_names.rs:87:16
    |
 LL |         apple: spring,
    |                ^^^^^^

src/tools/clippy/tests/ui/swap.fixed

@@ -6,6 +6,7 @@
     clippy::no_effect,
     clippy::redundant_clone,
     redundant_semicolons,
+    dead_code,
     unused_assignments
 )]
 
@@ -20,9 +21,7 @@ struct Bar {
 fn field() {
     let mut bar = Bar { a: 1, b: 2 };
 
-    let temp = bar.a;
+    std::mem::swap(&mut bar.a, &mut bar.b);
-    bar.a = bar.b;
-    bar.b = temp;
 
     let mut baz = vec![bar.clone(), bar.clone()];
     let temp = baz[0].a;
@@ -51,6 +50,7 @@ fn unswappable_slice() {
     foo[1][0] = temp;
 
     // swap(foo[0][1], foo[1][0]) would fail
+    // this could use split_at_mut and mem::swap, but that is not much simpler.
 }
 
 fn vec() {
@@ -60,13 +60,54 @@ fn vec() {
     foo.swap(0, 1);
 }
 
+fn xor_swap_locals() {
+    // This is an xor-based swap of local variables.
+    let mut a = 0;
+    let mut b = 1;
+    std::mem::swap(&mut a, &mut b)
+}
+
+fn xor_field_swap() {
+    // This is an xor-based swap of fields in a struct.
+    let mut bar = Bar { a: 0, b: 1 };
+    std::mem::swap(&mut bar.a, &mut bar.b)
+}
+
+fn xor_slice_swap() {
+    // This is an xor-based swap of a slice
+    let foo = &mut [1, 2];
+    foo.swap(0, 1)
+}
+
+fn xor_no_swap() {
+    // This is a sequence of xor-assignment statements that doesn't result in a swap.
+    let mut a = 0;
+    let mut b = 1;
+    let mut c = 2;
+    a ^= b;
+    b ^= c;
+    a ^= c;
+    c ^= a;
+}
+
+fn xor_unswappable_slice() {
+    let foo = &mut [vec![1, 2], vec![3, 4]];
+    foo[0][1] ^= foo[1][0];
+    foo[1][0] ^= foo[0][0];
+    foo[0][1] ^= foo[1][0];
+
+    // swap(foo[0][1], foo[1][0]) would fail
+    // this could use split_at_mut and mem::swap, but that is not much simpler.
+}
+
+fn distinct_slice() {
+    let foo = &mut [vec![1, 2], vec![3, 4]];
+    let bar = &mut [vec![1, 2], vec![3, 4]];
+    std::mem::swap(&mut foo[0][1], &mut bar[1][0]);
+}
+
 #[rustfmt::skip]
 fn main() {
-    field();
-    array();
-    slice();
-    unswappable_slice();
-    vec();
 
     let mut a = 42;
     let mut b = 1337;

src/tools/clippy/tests/ui/swap.rs

@@ -6,6 +6,7 @@
     clippy::no_effect,
     clippy::redundant_clone,
     redundant_semicolons,
+    dead_code,
     unused_assignments
 )]
 
@@ -55,6 +56,7 @@ fn unswappable_slice() {
     foo[1][0] = temp;
 
     // swap(foo[0][1], foo[1][0]) would fail
+    // this could use split_at_mut and mem::swap, but that is not much simpler.
 }
 
 fn vec() {
@@ -66,13 +68,62 @@ fn vec() {
     foo.swap(0, 1);
 }
 
+fn xor_swap_locals() {
+    // This is an xor-based swap of local variables.
+    let mut a = 0;
+    let mut b = 1;
+    a ^= b;
+    b ^= a;
+    a ^= b;
+}
+
+fn xor_field_swap() {
+    // This is an xor-based swap of fields in a struct.
+    let mut bar = Bar { a: 0, b: 1 };
+    bar.a ^= bar.b;
+    bar.b ^= bar.a;
+    bar.a ^= bar.b;
+}
+
+fn xor_slice_swap() {
+    // This is an xor-based swap of a slice
+    let foo = &mut [1, 2];
+    foo[0] ^= foo[1];
+    foo[1] ^= foo[0];
+    foo[0] ^= foo[1];
+}
+
+fn xor_no_swap() {
+    // This is a sequence of xor-assignment statements that doesn't result in a swap.
+    let mut a = 0;
+    let mut b = 1;
+    let mut c = 2;
+    a ^= b;
+    b ^= c;
+    a ^= c;
+    c ^= a;
+}
+
+fn xor_unswappable_slice() {
+    let foo = &mut [vec![1, 2], vec![3, 4]];
+    foo[0][1] ^= foo[1][0];
+    foo[1][0] ^= foo[0][0];
+    foo[0][1] ^= foo[1][0];
+
+    // swap(foo[0][1], foo[1][0]) would fail
+    // this could use split_at_mut and mem::swap, but that is not much simpler.
+}
+
+fn distinct_slice() {
+    let foo = &mut [vec![1, 2], vec![3, 4]];
+    let bar = &mut [vec![1, 2], vec![3, 4]];
+    let temp = foo[0][1];
+    foo[0][1] = bar[1][0];
+    bar[1][0] = temp;
+}
+
 #[rustfmt::skip]
 fn main() {
-    field();
-    array();
-    slice();
-    unswappable_slice();
-    vec();
 
     let mut a = 42;
     let mut b = 1337;

src/tools/clippy/tests/ui/swap.stderr

@@ -1,15 +1,16 @@
-error: this looks like you are swapping elements of `foo` manually
+error: this looks like you are swapping `bar.a` and `bar.b` manually
-  --> $DIR/swap.rs:35:5
+  --> $DIR/swap.rs:24:5
    |
-LL | /     let temp = foo[0];
+LL | /     let temp = bar.a;
-LL | |     foo[0] = foo[1];
+LL | |     bar.a = bar.b;
-LL | |     foo[1] = temp;
+LL | |     bar.b = temp;
-   | |_________________^ help: try: `foo.swap(0, 1)`
+   | |________________^ help: try: `std::mem::swap(&mut bar.a, &mut bar.b)`
    |
    = note: `-D clippy::manual-swap` implied by `-D warnings`
+   = note: or maybe you should use `std::mem::replace`?
 
 error: this looks like you are swapping elements of `foo` manually
-  --> $DIR/swap.rs:44:5
+  --> $DIR/swap.rs:36:5
    |
 LL | /     let temp = foo[0];
 LL | |     foo[0] = foo[1];
@@ -17,7 +18,15 @@ LL | |     foo[1] = temp;
    | |_________________^ help: try: `foo.swap(0, 1)`
 
 error: this looks like you are swapping elements of `foo` manually
-  --> $DIR/swap.rs:62:5
+  --> $DIR/swap.rs:45:5
+   |
+LL | /     let temp = foo[0];
+LL | |     foo[0] = foo[1];
+LL | |     foo[1] = temp;
+   | |_________________^ help: try: `foo.swap(0, 1)`
+
+error: this looks like you are swapping elements of `foo` manually
+  --> $DIR/swap.rs:64:5
    |
 LL | /     let temp = foo[0];
 LL | |     foo[0] = foo[1];
@@ -25,7 +34,41 @@ LL | |     foo[1] = temp;
    | |_________________^ help: try: `foo.swap(0, 1)`
 
 error: this looks like you are swapping `a` and `b` manually
-  --> $DIR/swap.rs:83:7
+  --> $DIR/swap.rs:75:5
+   |
+LL | /     a ^= b;
+LL | |     b ^= a;
+LL | |     a ^= b;
+   | |___________^ help: try: `std::mem::swap(&mut a, &mut b)`
+
+error: this looks like you are swapping `bar.a` and `bar.b` manually
+  --> $DIR/swap.rs:83:5
+   |
+LL | /     bar.a ^= bar.b;
+LL | |     bar.b ^= bar.a;
+LL | |     bar.a ^= bar.b;
+   | |___________________^ help: try: `std::mem::swap(&mut bar.a, &mut bar.b)`
+
+error: this looks like you are swapping elements of `foo` manually
+  --> $DIR/swap.rs:91:5
+   |
+LL | /     foo[0] ^= foo[1];
+LL | |     foo[1] ^= foo[0];
+LL | |     foo[0] ^= foo[1];
+   | |_____________________^ help: try: `foo.swap(0, 1)`
+
+error: this looks like you are swapping `foo[0][1]` and `bar[1][0]` manually
+  --> $DIR/swap.rs:120:5
+   |
+LL | /     let temp = foo[0][1];
+LL | |     foo[0][1] = bar[1][0];
+LL | |     bar[1][0] = temp;
+   | |____________________^ help: try: `std::mem::swap(&mut foo[0][1], &mut bar[1][0])`
+   |
+   = note: or maybe you should use `std::mem::replace`?
+
+error: this looks like you are swapping `a` and `b` manually
+  --> $DIR/swap.rs:134:7
    |
 LL |       ; let t = a;
    |  _______^
@@ -36,7 +79,7 @@ LL | |     b = t;
    = note: or maybe you should use `std::mem::replace`?
 
 error: this looks like you are swapping `c.0` and `a` manually
-  --> $DIR/swap.rs:92:7
+  --> $DIR/swap.rs:143:7
    |
 LL |       ; let t = c.0;
    |  _______^
@@ -47,7 +90,7 @@ LL | |     a = t;
    = note: or maybe you should use `std::mem::replace`?
 
 error: this looks like you are trying to swap `a` and `b`
-  --> $DIR/swap.rs:80:5
+  --> $DIR/swap.rs:131:5
    |
 LL | /     a = b;
 LL | |     b = a;
@@ -57,7 +100,7 @@ LL | |     b = a;
    = note: or maybe you should use `std::mem::replace`?
 
 error: this looks like you are trying to swap `c.0` and `a`
-  --> $DIR/swap.rs:89:5
+  --> $DIR/swap.rs:140:5
    |
 LL | /     c.0 = a;
 LL | |     a = c.0;
@@ -65,5 +108,5 @@ LL | |     a = c.0;
    |
    = note: or maybe you should use `std::mem::replace`?
 
-error: aborting due to 7 previous errors
+error: aborting due to 12 previous errors
 

src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs

@@ -58,6 +58,8 @@ impl Foo {
     fn bad(&self, x: &u32, y: &Foo, z: &Baz) {}
 
     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
+
+    fn bad_issue7518(self, other: &Self) {}
 }
 
 impl AsRef<u32> for Foo {

src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr

@@ -65,40 +65,46 @@ LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                                  ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:72:16
+  --> $DIR/trivially_copy_pass_by_ref.rs:62:35
+   |
+LL |     fn bad_issue7518(self, other: &Self) {}
+   |                                   ^^^^^ help: consider passing by value instead: `Self`
+
+error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
+  --> $DIR/trivially_copy_pass_by_ref.rs:74:16
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                ^^^^ help: consider passing by value instead: `u32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:72:25
+  --> $DIR/trivially_copy_pass_by_ref.rs:74:25
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                         ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:72:34
+  --> $DIR/trivially_copy_pass_by_ref.rs:74:34
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                                  ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:76:34
+  --> $DIR/trivially_copy_pass_by_ref.rs:78:34
    |
 LL |     fn trait_method(&self, _foo: &Foo);
    |                                  ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:108:21
+  --> $DIR/trivially_copy_pass_by_ref.rs:110:21
    |
 LL |     fn foo_never(x: &i32) {
    |                     ^^^^ help: consider passing by value instead: `i32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:113:15
+  --> $DIR/trivially_copy_pass_by_ref.rs:115:15
    |
 LL |     fn foo(x: &i32) {
    |               ^^^^ help: consider passing by value instead: `i32`
 
-error: aborting due to 16 previous errors
+error: aborting due to 17 previous errors
 

src/tools/clippy/tests/ui/unwrap_or_else_default.fixed

@@ -0,0 +1,71 @@
+// run-rustfix
+
+#![warn(clippy::unwrap_or_else_default)]
+#![allow(dead_code)]
+#![allow(clippy::unnecessary_wraps)]
+
+/// Checks implementation of the `UNWRAP_OR_ELSE_DEFAULT` lint.
+fn unwrap_or_else_default() {
+    struct Foo;
+
+    impl Foo {
+        fn new() -> Foo {
+            Foo
+        }
+
+        // fake default, we should not trigger on this
+        fn default() -> Foo {
+            Foo
+        }
+    }
+
+    struct HasDefaultAndDuplicate;
+
+    impl HasDefaultAndDuplicate {
+        fn default() -> Self {
+            HasDefaultAndDuplicate
+        }
+    }
+
+    impl Default for HasDefaultAndDuplicate {
+        fn default() -> Self {
+            HasDefaultAndDuplicate
+        }
+    }
+
+    enum Enum {
+        A(),
+    }
+
+    fn make<T, V>(_: V) -> T {
+        unimplemented!();
+    }
+
+    let with_enum = Some(Enum::A());
+    with_enum.unwrap_or_else(Enum::A);
+
+    let with_new = Some(vec![1]);
+    with_new.unwrap_or_else(Vec::new);
+
+    let with_err: Result<_, ()> = Ok(vec![1]);
+    with_err.unwrap_or_else(make);
+
+    // should not be changed
+    let with_fake_default = None::<Foo>;
+    with_fake_default.unwrap_or_else(Foo::default);
+
+    // should not be changed
+    let with_fake_default2 = None::<HasDefaultAndDuplicate>;
+    with_fake_default2.unwrap_or_else(<HasDefaultAndDuplicate>::default);
+
+    let with_real_default = None::<HasDefaultAndDuplicate>;
+    with_real_default.unwrap_or_default();
+
+    let with_default_trait = Some(1);
+    with_default_trait.unwrap_or_default();
+
+    let with_default_type = Some(1);
+    with_default_type.unwrap_or_default();
+}
+
+fn main() {}

src/tools/clippy/tests/ui/unwrap_or_else_default.rs

@@ -0,0 +1,71 @@
+// run-rustfix
+
+#![warn(clippy::unwrap_or_else_default)]
+#![allow(dead_code)]
+#![allow(clippy::unnecessary_wraps)]
+
+/// Checks implementation of the `UNWRAP_OR_ELSE_DEFAULT` lint.
+fn unwrap_or_else_default() {
+    struct Foo;
+
+    impl Foo {
+        fn new() -> Foo {
+            Foo
+        }
+
+        // fake default, we should not trigger on this
+        fn default() -> Foo {
+            Foo
+        }
+    }
+
+    struct HasDefaultAndDuplicate;
+
+    impl HasDefaultAndDuplicate {
+        fn default() -> Self {
+            HasDefaultAndDuplicate
+        }
+    }
+
+    impl Default for HasDefaultAndDuplicate {
+        fn default() -> Self {
+            HasDefaultAndDuplicate
+        }
+    }
+
+    enum Enum {
+        A(),
+    }
+
+    fn make<T, V>(_: V) -> T {
+        unimplemented!();
+    }
+
+    let with_enum = Some(Enum::A());
+    with_enum.unwrap_or_else(Enum::A);
+
+    let with_new = Some(vec![1]);
+    with_new.unwrap_or_else(Vec::new);
+
+    let with_err: Result<_, ()> = Ok(vec![1]);
+    with_err.unwrap_or_else(make);
+
+    // should not be changed
+    let with_fake_default = None::<Foo>;
+    with_fake_default.unwrap_or_else(Foo::default);
+
+    // should not be changed
+    let with_fake_default2 = None::<HasDefaultAndDuplicate>;
+    with_fake_default2.unwrap_or_else(<HasDefaultAndDuplicate>::default);
+
+    let with_real_default = None::<HasDefaultAndDuplicate>;
+    with_real_default.unwrap_or_else(<HasDefaultAndDuplicate as Default>::default);
+
+    let with_default_trait = Some(1);
+    with_default_trait.unwrap_or_else(Default::default);
+
+    let with_default_type = Some(1);
+    with_default_type.unwrap_or_else(u64::default);
+}
+
+fn main() {}

src/tools/clippy/tests/ui/unwrap_or_else_default.stderr

@@ -0,0 +1,22 @@
+error: use of `.unwrap_or_else(..)` to construct default value
+  --> $DIR/unwrap_or_else_default.rs:62:5
+   |
+LL |     with_real_default.unwrap_or_else(<HasDefaultAndDuplicate as Default>::default);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `with_real_default.unwrap_or_default()`
+   |
+   = note: `-D clippy::unwrap-or-else-default` implied by `-D warnings`
+
+error: use of `.unwrap_or_else(..)` to construct default value
+  --> $DIR/unwrap_or_else_default.rs:65:5
+   |
+LL |     with_default_trait.unwrap_or_else(Default::default);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `with_default_trait.unwrap_or_default()`
+
+error: use of `.unwrap_or_else(..)` to construct default value
+  --> $DIR/unwrap_or_else_default.rs:68:5
+   |
+LL |     with_default_type.unwrap_or_else(u64::default);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `with_default_type.unwrap_or_default()`
+
+error: aborting due to 3 previous errors
+

src/tools/clippy/tests/ui/while_let_on_iterator.fixed

@@ -334,6 +334,38 @@ fn issue7249() {
     x();
 }
 
+fn issue7510() {
+    let mut it = 0..10;
+    let it = &mut it;
+    // Needs to reborrow `it` as the binding isn't mutable
+    for x in &mut *it {
+        if x % 2 == 0 {
+            break;
+        }
+    }
+    println!("{}", it.next().unwrap());
+
+    struct S<T>(T);
+    let mut it = 0..10;
+    let it = S(&mut it);
+    // Needs to reborrow `it.0` as the binding isn't mutable
+    for x in &mut *it.0 {
+        if x % 2 == 0 {
+            break;
+        }
+    }
+    println!("{}", it.0.next().unwrap());
+}
+
+fn exact_match_with_single_field() {
+    struct S<T>(T);
+    let mut s = S(0..10);
+    // Don't lint. `s.0` is used inside the loop.
+    while let Some(_) = s.0.next() {
+        let _ = &mut s.0;
+    }
+}
+
 fn main() {
     let mut it = 0..20;
     for _ in it {

src/tools/clippy/tests/ui/while_let_on_iterator.rs

@@ -334,6 +334,38 @@ fn issue7249() {
     x();
 }
 
+fn issue7510() {
+    let mut it = 0..10;
+    let it = &mut it;
+    // Needs to reborrow `it` as the binding isn't mutable
+    while let Some(x) = it.next() {
+        if x % 2 == 0 {
+            break;
+        }
+    }
+    println!("{}", it.next().unwrap());
+
+    struct S<T>(T);
+    let mut it = 0..10;
+    let it = S(&mut it);
+    // Needs to reborrow `it.0` as the binding isn't mutable
+    while let Some(x) = it.0.next() {
+        if x % 2 == 0 {
+            break;
+        }
+    }
+    println!("{}", it.0.next().unwrap());
+}
+
+fn exact_match_with_single_field() {
+    struct S<T>(T);
+    let mut s = S(0..10);
+    // Don't lint. `s.0` is used inside the loop.
+    while let Some(_) = s.0.next() {
+        let _ = &mut s.0;
+    }
+}
+
 fn main() {
     let mut it = 0..20;
     while let Some(..) = it.next() {

src/tools/clippy/tests/ui/while_let_on_iterator.stderr

@@ -111,10 +111,22 @@ LL |         while let Some(x) = it.next() {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut it`
 
 error: this loop could be written as a `for` loop
-  --> $DIR/while_let_on_iterator.rs:339:5
+  --> $DIR/while_let_on_iterator.rs:341:5
+   |
+LL |     while let Some(x) = it.next() {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut *it`
+
+error: this loop could be written as a `for` loop
+  --> $DIR/while_let_on_iterator.rs:352:5
+   |
+LL |     while let Some(x) = it.0.next() {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut *it.0`
+
+error: this loop could be written as a `for` loop
+  --> $DIR/while_let_on_iterator.rs:371:5
    |
 LL |     while let Some(..) = it.next() {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for _ in it`
 
-error: aborting due to 19 previous errors
+error: aborting due to 21 previous errors