27 files changed, 297 insertions, 102 deletions

diff --git a/crates/hir_def/src/data.rs b/crates/hir_def/src/data.rs
index d2bb381be..52cb7777b 100644
--- a/crates/hir_def/src/data.rs
+++ b/crates/hir_def/src/data.rs
@@ -143,6 +143,10 @@ pub struct TraitData {
     pub is_auto: bool,
     pub is_unsafe: bool,
     pub visibility: RawVisibility,
+    /// Whether the trait has `#[rust_skip_array_during_method_dispatch]`. `hir_ty` will ignore
+    /// method calls to this trait's methods when the receiver is an array and the crate edition is
+    /// 2015 or 2018.
+    pub skip_array_during_method_dispatch: bool,
 }
 
 impl TraitData {
@@ -157,6 +161,10 @@ impl TraitData {
         let container = AssocContainerId::TraitId(tr);
         let visibility = item_tree[tr_def.visibility].clone();
         let mut expander = Expander::new(db, tr_loc.id.file_id(), module_id);
+        let skip_array_during_method_dispatch = item_tree
+            .attrs(db, tr_loc.container.krate(), ModItem::from(tr_loc.id.value).into())
+            .by_key("rustc_skip_array_during_method_dispatch")
+            .exists();
 
         let items = collect_items(
             db,
@@ -168,7 +176,14 @@ impl TraitData {
             100,
         );
 
-        Arc::new(TraitData { name, items, is_auto, is_unsafe, visibility })
+        Arc::new(TraitData {
+            name,
+            items,
+            is_auto,
+            is_unsafe,
+            visibility,
+            skip_array_during_method_dispatch,
+        })
     }
 
     pub fn associated_types(&self) -> impl Iterator<Item = TypeAliasId> + '_ {
diff --git a/crates/hir_def/src/item_tree/lower.rs b/crates/hir_def/src/item_tree/lower.rs
index 6208facd5..cfda7cb32 100644
--- a/crates/hir_def/src/item_tree/lower.rs
+++ b/crates/hir_def/src/item_tree/lower.rs
@@ -130,7 +130,7 @@ impl<'a> Ctx<'a> {
             ast::Item::ExternBlock(ast) => self.lower_extern_block(ast).into(),
         };
 
-        self.add_attrs(item.into(), attrs.clone());
+        self.add_attrs(item.into(), attrs);
 
         Some(item)
     }
@@ -276,10 +276,11 @@ impl<'a> Ctx<'a> {
         let visibility = self.lower_visibility(enum_);
         let name = enum_.name()?.as_name();
         let generic_params = self.lower_generic_params(GenericsOwner::Enum, enum_);
-        let variants = match &enum_.variant_list() {
-            Some(variant_list) => self.lower_variants(variant_list),
-            None => IdRange::new(self.next_variant_idx()..self.next_variant_idx()),
-        };
+        let variants =
+            self.with_inherited_visibility(visibility, |this| match &enum_.variant_list() {
+                Some(variant_list) => this.lower_variants(variant_list),
+                None => IdRange::new(this.next_variant_idx()..this.next_variant_idx()),
+            });
         let ast_id = self.source_ast_id_map.ast_id(enum_);
         let res = Enum { name, visibility, generic_params, variants, ast_id };
         Some(id(self.data().enums.alloc(res)))
diff --git a/crates/hir_def/src/item_tree/tests.rs b/crates/hir_def/src/item_tree/tests.rs
index b362add5c..57686dc6e 100644
--- a/crates/hir_def/src/item_tree/tests.rs
+++ b/crates/hir_def/src/item_tree/tests.rs
@@ -359,3 +359,41 @@ trait Tr<'a, T: 'a>: Super {}
         "#]],
     )
 }
+
+#[test]
+fn inherit_visibility() {
+    check(
+        r#"
+pub(crate) enum En {
+    Var1(u8),
+    Var2 {
+        fld: u8,
+    },
+}
+
+pub(crate) trait Tr {
+    fn f();
+    fn method(&self) {}
+}
+        "#,
+        expect![[r#"
+            pub(crate) enum En {
+                Var1(
+                    pub(crate) 0: u8,
+                ),
+                Var2 {
+                    pub(crate) fld: u8,
+                },
+            }
+
+            pub(crate) trait Tr<Self> {
+                pub(crate) fn f() -> ();
+
+                // flags = 0x3
+                pub(crate) fn method(
+                    _: &Self,
+                ) -> ();
+            }
+        "#]],
+    )
+}
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 3efbce773..a2a4d61db 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -357,17 +357,20 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             infer: &infer,
             db,
             pattern_arena: &pattern_arena,
-            eprint_panic_context: &|| {
+            panic_context: &|| {
                 use syntax::AstNode;
-                if let Ok(scrutinee_sptr) = source_map.expr_syntax(match_expr) {
-                    let root = scrutinee_sptr.file_syntax(db.upcast());
-                    if let Some(match_ast) = scrutinee_sptr.value.to_node(&root).syntax().parent() {
-                        eprintln!(
-                            "Match checking is about to panic on this expression:\n{}",
-                            match_ast.to_string(),
-                        );
-                    }
-                }
+                let match_expr_text = source_map
+                    .expr_syntax(match_expr)
+                    .ok()
+                    .and_then(|scrutinee_sptr| {
+                        let root = scrutinee_sptr.file_syntax(db.upcast());
+                        scrutinee_sptr.value.to_node(&root).syntax().parent()
+                    })
+                    .map(|node| node.to_string());
+                format!(
+                    "expression:\n{}",
+                    match_expr_text.as_deref().unwrap_or("<synthesized expr>")
+                )
             },
         };
         let report = compute_match_usefulness(&cx, &m_arms);
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index a9a99f57a..c8e1b23de 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -100,10 +100,19 @@ impl<'a> PatCtxt<'a> {
     }
 
     pub(crate) fn lower_pattern(&mut self, pat: hir_def::expr::PatId) -> Pat {
-        // FIXME: implement pattern adjustments (implicit pattern dereference; "RFC 2005-match-ergonomics")
+        // XXX(iDawer): Collecting pattern adjustments feels imprecise to me.
+        // When lowering of & and box patterns are implemented this should be tested
+        // in a manner of `match_ergonomics_issue_9095` test.
+        // Pattern adjustment is part of RFC 2005-match-ergonomics.
         // More info https://github.com/rust-lang/rust/issues/42640#issuecomment-313535089
         let unadjusted_pat = self.lower_pattern_unadjusted(pat);
-        unadjusted_pat
+        self.infer.pat_adjustments.get(&pat).map(|it| &**it).unwrap_or_default().iter().rev().fold(
+            unadjusted_pat,
+            |subpattern, ref_ty| Pat {
+                ty: ref_ty.clone(),
+                kind: Box::new(PatKind::Deref { subpattern }),
+            },
+        )
     }
 
     fn lower_pattern_unadjusted(&mut self, pat: hir_def::expr::PatId) -> Pat {
@@ -1236,6 +1245,21 @@ fn main(f: Foo) {
         );
     }
 
+    #[test]
+    fn match_ergonomics_issue_9095() {
+        check_diagnostics(
+            r#"
+enum Foo<T> { A(T) }
+fn main() {
+    match &Foo::A(true) {
+        _ => {}
+        Foo::A(_) => {}
+    }
+}
+"#,
+        );
+    }
+
     mod false_negatives {
         //! The implementation of match checking here is a work in progress. As we roll this out, we
         //! prefer false negatives to false positives (ideally there would be no false positives). This
diff --git a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
index 83b094a89..bd76a606c 100644
--- a/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
+++ b/crates/hir_ty/src/diagnostics/match_check/usefulness.rs
@@ -295,7 +295,7 @@ pub(crate) struct MatchCheckCtx<'a> {
     pub(crate) db: &'a dyn HirDatabase,
     /// Lowered patterns from arms plus generated by the check.
     pub(crate) pattern_arena: &'a RefCell<PatternArena>,
-    pub(crate) eprint_panic_context: &'a dyn Fn(),
+    pub(crate) panic_context: &'a dyn Fn() -> String,
 }
 
 impl<'a> MatchCheckCtx<'a> {
@@ -331,8 +331,7 @@ impl<'a> MatchCheckCtx<'a> {
 
     #[track_caller]
     pub(super) fn bug(&self, info: &str) -> ! {
-        (self.eprint_panic_context)();
-        panic!("bug: {}", info);
+        panic!("bug: {}\n{}", info, (self.panic_context)());
     }
 }
 
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 7a4268819..0e9f777da 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -150,6 +150,8 @@ pub struct InferenceResult {
     type_mismatches: FxHashMap<ExprOrPatId, TypeMismatch>,
     /// Interned Unknown to return references to.
     standard_types: InternedStandardTypes,
+    /// Stores the types which were implicitly dereferenced in pattern binding modes.
+    pub pat_adjustments: FxHashMap<PatId, Vec<Ty>>,
 }
 
 impl InferenceResult {
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index 83e0a7a9e..25dff7e49 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -101,7 +101,9 @@ impl<'a> InferenceContext<'a> {
         let mut expected = self.resolve_ty_shallow(expected);
 
         if is_non_ref_pat(&body, pat) {
+            let mut pat_adjustments = Vec::new();
             while let Some((inner, _lifetime, mutability)) = expected.as_reference() {
+                pat_adjustments.push(expected.clone());
                 expected = self.resolve_ty_shallow(inner);
                 default_bm = match default_bm {
                     BindingMode::Move => BindingMode::Ref(mutability),
@@ -109,6 +111,11 @@ impl<'a> InferenceContext<'a> {
                     BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
                 }
             }
+
+            if !pat_adjustments.is_empty() {
+                pat_adjustments.shrink_to_fit();
+                self.result.pat_adjustments.insert(pat, pat_adjustments);
+            }
         } else if let Pat::Ref { .. } = &body[pat] {
             cov_mark::hit!(match_ergonomics_ref);
             // When you encounter a `&pat` pattern, reset to Move.
@@ -290,6 +297,10 @@ fn is_non_ref_pat(body: &hir_def::body::Body, pat: PatId) -> bool {
             Expr::Literal(Literal::String(..)) => false,
             _ => true,
         },
+        Pat::Bind { mode: BindingAnnotation::Mutable, subpat: Some(subpat), .. }
+        | Pat::Bind { mode: BindingAnnotation::Unannotated, subpat: Some(subpat), .. } => {
+            is_non_ref_pat(body, *subpat)
+        }
         Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Box { .. } | Pat::Missing => false,
     }
 }
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index af6b6cda7..a23527f7d 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -5,7 +5,7 @@
 use std::{iter, sync::Arc};
 
 use arrayvec::ArrayVec;
-use base_db::CrateId;
+use base_db::{CrateId, Edition};
 use chalk_ir::{cast::Cast, Mutability, UniverseIndex};
 use hir_def::{
     lang_item::LangItemTarget, nameres::DefMap, AssocContainerId, AssocItemId, FunctionId,
@@ -639,6 +639,7 @@ fn iterate_trait_method_candidates(
     receiver_ty: Option<&Canonical<Ty>>,
     callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool,
 ) -> bool {
+    let receiver_is_array = matches!(self_ty.value.kind(&Interner), chalk_ir::TyKind::Array(..));
     // if ty is `dyn Trait`, the trait doesn't need to be in scope
     let inherent_trait =
         self_ty.value.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t));
@@ -655,6 +656,19 @@ fn iterate_trait_method_candidates(
     'traits: for t in traits {
         let data = db.trait_data(t);
 
+        // Traits annotated with `#[rustc_skip_array_during_method_dispatch]` are skipped during
+        // method resolution, if the receiver is an array, and we're compiling for editions before
+        // 2021.
+        // This is to make `[a].into_iter()` not break code with the new `IntoIterator` impl for
+        // arrays.
+        if data.skip_array_during_method_dispatch && receiver_is_array {
+            // FIXME: this should really be using the edition of the method name's span, in case it
+            // comes from a macro
+            if db.crate_graph()[krate].edition < Edition::Edition2021 {
+                continue;
+            }
+        }
+
         // we'll be lazy about checking whether the type implements the
         // trait, but if we find out it doesn't, we'll skip the rest of the
         // iteration
diff --git a/crates/hir_ty/src/tests/method_resolution.rs b/crates/hir_ty/src/tests/method_resolution.rs
index 058eb9129..f26b2c8a7 100644
--- a/crates/hir_ty/src/tests/method_resolution.rs
+++ b/crates/hir_ty/src/tests/method_resolution.rs
@@ -1349,3 +1349,52 @@ fn f() {
     "#,
     );
 }
+
+#[test]
+fn skip_array_during_method_dispatch() {
+    check_types(
+        r#"
+//- /main2018.rs crate:main2018 deps:core
+use core::IntoIterator;
+
+fn f() {
+    let v = [4].into_iter();
+    v;
+  //^ &i32
+
+    let a = [0, 1].into_iter();
+    a;
+  //^ &i32
+}
+
+//- /main2021.rs crate:main2021 deps:core edition:2021
+use core::IntoIterator;
+
+fn f() {
+    let v = [4].into_iter();
+    v;
+  //^ i32
+
+    let a = [0, 1].into_iter();
+    a;
+  //^ &i32
+}
+
+//- /core.rs crate:core
+#[rustc_skip_array_during_method_dispatch]
+pub trait IntoIterator {
+    type Out;
+    fn into_iter(self) -> Self::Out;
+}
+
+impl<T> IntoIterator for [T; 1] {
+    type Out = T;
+    fn into_iter(self) -> Self::Out {}
+}
+impl<'a, T> IntoIterator for &'a [T] {
+    type Out = &'a T;
+    fn into_iter(self) -> Self::Out {}
+}
+    "#,
+    );
+}
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index cd08b5c7a..7d00cee9b 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -20,6 +20,8 @@ fn infer_pattern() {
                 let h = val;
             }
 
+            if let x @ true = &true {}
+
             let lambda = |a: u64, b, c: i32| { a + b; c };
 
             let ref ref_to_x = x;
@@ -30,7 +32,7 @@ fn infer_pattern() {
         "#,
         expect![[r#"
             8..9 'x': &i32
-            17..368 '{     ...o_x; }': ()
+            17..400 '{     ...o_x; }': ()
             27..28 'y': &i32
             31..32 'x': &i32
             42..44 '&z': &i32
@@ -59,24 +61,31 @@ fn infer_pattern() {
             176..204 '{     ...     }': ()
             190..191 'h': {unknown}
             194..197 'val': {unknown}
-            214..220 'lambda': |u64, u64, i32| -> i32
-            223..255 '|a: u6...b; c }': |u64, u64, i32| -> i32
-            224..225 'a': u64
-            232..233 'b': u64
-            235..236 'c': i32
-            243..255 '{ a + b; c }': i32
-            245..246 'a': u64
-            245..250 'a + b': u64
-            249..250 'b': u64
-            252..253 'c': i32
-            266..278 'ref ref_to_x': &&i32
-            281..282 'x': &i32
-            292..301 'mut mut_x': &i32
-            304..305 'x': &i32
-            315..335 'ref mu...f_to_x': &mut &i32
-            338..339 'x': &i32
-            349..350 'k': &mut &i32
-            353..365 'mut_ref_to_x': &mut &i32
+            210..236 'if let...rue {}': ()
+            217..225 'x @ true': &bool
+            221..225 'true': bool
+            221..225 'true': bool
+            228..233 '&true': &bool
+            229..233 'true': bool
+            234..236 '{}': ()
+            246..252 'lambda': |u64, u64, i32| -> i32
+            255..287 '|a: u6...b; c }': |u64, u64, i32| -> i32
+            256..257 'a': u64
+            264..265 'b': u64
+            267..268 'c': i32
+            275..287 '{ a + b; c }': i32
+            277..278 'a': u64
+            277..282 'a + b': u64
+            281..282 'b': u64
+            284..285 'c': i32
+            298..310 'ref ref_to_x': &&i32
+            313..314 'x': &i32
+            324..333 'mut mut_x': &i32
+            336..337 'x': &i32
+            347..367 'ref mu...f_to_x': &mut &i32
+            370..371 'x': &i32
+            381..382 'k': &mut &i32
+            385..397 'mut_ref_to_x': &mut &i32
         "#]],
     );
 }
diff --git a/crates/ide/src/expand_macro.rs b/crates/ide/src/expand_macro.rs
index eebae5ebe..e0d01fa96 100644
--- a/crates/ide/src/expand_macro.rs
+++ b/crates/ide/src/expand_macro.rs
@@ -28,8 +28,8 @@ pub struct ExpandedMacro {
 pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<ExpandedMacro> {
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id);
-    let name_ref = find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset)?;
-    let mac = name_ref.syntax().ancestors().find_map(ast::MacroCall::cast)?;
+    let mac = find_node_at_offset::<ast::MacroCall>(file.syntax(), position.offset)?;
+    let name = mac.path()?.segment()?.name_ref()?;
 
     let expanded = expand_macro_recur(&sema, &mac)?;
 
@@ -37,7 +37,7 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
     // macro expansion may lose all white space information
     // But we hope someday we can use ra_fmt for that
     let expansion = insert_whitespaces(expanded);
-    Some(ExpandedMacro { name: name_ref.text().to_string(), expansion })
+    Some(ExpandedMacro { name: name.to_string(), expansion })
 }
 
 fn expand_macro_recur(
diff --git a/crates/ide_assists/src/handlers/extract_type_alias.rs b/crates/ide_assists/src/handlers/extract_type_alias.rs
index 998e0de7b..eac8857c6 100644
--- a/crates/ide_assists/src/handlers/extract_type_alias.rs
+++ b/crates/ide_assists/src/handlers/extract_type_alias.rs
@@ -1,4 +1,7 @@
-use syntax::ast::{self, AstNode};
+use syntax::{
+    ast::{self, edit::IndentLevel, AstNode},
+    match_ast,
+};
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 
@@ -25,12 +28,15 @@ pub(crate) fn extract_type_alias(acc: &mut Assists, ctx: &AssistContext) -> Opti
     }
 
     let node = ctx.find_node_at_range::<ast::Type>()?;
-    let insert = ctx
-        .find_node_at_offset::<ast::Impl>()
-        .map(|imp| imp.syntax().clone())
-        .or_else(|| ctx.find_node_at_offset::<ast::Item>().map(|item| item.syntax().clone()))?
-        .text_range()
-        .start();
+    let item = ctx.find_node_at_offset::<ast::Item>()?;
+    let insert = match_ast! {
+        match (item.syntax().parent()?) {
+            ast::AssocItemList(it) => it.syntax().parent()?,
+            _ => item.syntax().clone(),
+        }
+    };
+    let indent = IndentLevel::from_node(&insert);
+    let insert = insert.text_range().start();
     let target = node.syntax().text_range();
 
     acc.add(
@@ -42,10 +48,14 @@ pub(crate) fn extract_type_alias(acc: &mut Assists, ctx: &AssistContext) -> Opti
             builder.replace(target, "Type");
             match ctx.config.snippet_cap {
                 Some(cap) => {
-                    builder.insert_snippet(cap, insert, format!("type $0Type = {};\n\n", node));
+                    builder.insert_snippet(
+                        cap,
+                        insert,
+                        format!("type $0Type = {};\n\n{}", node, indent),
+                    );
                 }
                 None => {
-                    builder.insert(insert, format!("type Type = {};\n\n", node));
+                    builder.insert(insert, format!("type Type = {};\n\n{}", node, indent));
                 }
             }
         },
@@ -153,9 +163,9 @@ struct S {
     }
 
     #[test]
-    fn extract_from_impl() {
-        // When invoked in an impl, extracted type alias should be placed next to the impl, not
-        // inside.
+    fn extract_from_impl_or_trait() {
+        // When invoked in an impl/trait, extracted type alias should be placed next to the
+        // impl/trait, not inside.
         check_assist(
             extract_type_alias,
             r#"
@@ -171,5 +181,39 @@ impl S {
 }
             "#,
         );
+        check_assist(
+            extract_type_alias,
+            r#"
+trait Tr {
+    fn f() -> $0(u8, u8)$0 {}
+}
+            "#,
+            r#"
+type $0Type = (u8, u8);
+
+trait Tr {
+    fn f() -> Type {}
+}
+            "#,
+        );
+    }
+
+    #[test]
+    fn indentation() {
+        check_assist(
+            extract_type_alias,
+            r#"
+mod m {
+    fn f() -> $0u8$0 {}
+}
+            "#,
+            r#"
+mod m {
+    type $0Type = u8;
+
+    fn f() -> Type {}
+}
+            "#,
+        );
     }
 }
diff --git a/crates/ide_completion/src/context.rs b/crates/ide_completion/src/context.rs
index 6f685c02f..cb4f08e53 100644
--- a/crates/ide_completion/src/context.rs
+++ b/crates/ide_completion/src/context.rs
@@ -567,7 +567,7 @@ impl<'a> CompletionContext<'a> {
             None => return,
         };
 
-        if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
+        if let Some(segment) = ast::PathSegment::cast(parent) {
             let path = segment.parent_path();
             self.is_call = path
                 .syntax()
diff --git a/crates/mbe/src/benchmark.rs b/crates/mbe/src/benchmark.rs
index 38707ffa5..18eb97f0d 100644
--- a/crates/mbe/src/benchmark.rs
+++ b/crates/mbe/src/benchmark.rs
@@ -187,7 +187,7 @@ fn invocation_fixtures(rules: &FxHashMap<String, MacroRules>) -> Vec<(String, tt
             let a = 1664525;
             let c = 1013904223;
             *seed = usize::wrapping_add(usize::wrapping_mul(*seed, a), c);
-            return *seed;
+            *seed
         }
         fn make_ident(ident: &str) -> tt::TokenTree {
             tt::Leaf::Ident(tt::Ident { id: tt::TokenId::unspecified(), text: SmolStr::new(ident) })
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs
index 84ca3ff87..c982eb58f 100644
--- a/crates/mbe/src/expander/matcher.rs
+++ b/crates/mbe/src/expander/matcher.rs
@@ -219,7 +219,7 @@ impl BindingsBuilder {
         bindings
     }
 
-    fn build_inner(&self, bindings: &mut Bindings, link_nodes: &Vec<LinkNode<Rc<BindingKind>>>) {
+    fn build_inner(&self, bindings: &mut Bindings, link_nodes: &[LinkNode<Rc<BindingKind>>]) {
         let mut nodes = Vec::new();
         self.collect_nodes(&link_nodes, &mut nodes);
 
@@ -301,7 +301,7 @@ impl BindingsBuilder {
 
     fn collect_nodes<'a>(
         &'a self,
-        link_nodes: &'a Vec<LinkNode<Rc<BindingKind>>>,
+        link_nodes: &'a [LinkNode<Rc<BindingKind>>],
         nodes: &mut Vec<&'a Rc<BindingKind>>,
     ) {
         link_nodes.iter().for_each(|it| match it {
@@ -494,15 +494,8 @@ fn match_loop_inner<'t>(
                         }
                         Some(err) => {
                             res.add_err(err);
-                            match match_res.value {
-                                Some(fragment) => {
-                                    bindings_builder.push_fragment(
-                                        &mut item.bindings,
-                                        &name,
-                                        fragment,
-                                    );
-                                }
-                                _ => {}
+                            if let Some(fragment) = match_res.value {
+                                bindings_builder.push_fragment(&mut item.bindings, &name, fragment);
                             }
                             item.is_error = true;
                             error_items.push(item);
@@ -578,9 +571,9 @@ fn match_loop(pattern: &MetaTemplate, src: &tt::Subtree) -> Match {
         );
         stdx::always!(cur_items.is_empty());
 
-        if error_items.len() > 0 {
+        if !error_items.is_empty() {
             error_recover_item = error_items.pop().map(|it| it.bindings);
-        } else if eof_items.len() > 0 {
+        } else if !eof_items.is_empty() {
             error_recover_item = Some(eof_items[0].bindings.clone());
         }
 
@@ -793,7 +786,7 @@ impl<'a> TtIter<'a> {
             _ => (),
         }
 
-        let tt = self.next().ok_or_else(|| ())?.clone();
+        let tt = self.next().ok_or(())?.clone();
         let punct = match tt {
             tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) if punct.spacing == tt::Spacing::Joint => {
                 punct
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index b95374b76..380a50744 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -295,8 +295,8 @@ fn validate(pattern: &MetaTemplate) -> Result<(), ParseError> {
                 // Checks that no repetition which could match an empty token
                 // https://github.com/rust-lang/rust/blob/a58b1ed44f5e06976de2bdc4d7dc81c36a96934f/src/librustc_expand/mbe/macro_rules.rs#L558
 
-                if separator.is_none() {
-                    if subtree.iter().all(|child_op| {
+                if separator.is_none()
+                    && subtree.iter().all(|child_op| {
                         match child_op {
                             Op::Var { kind, .. } => {
                                 // vis is optional
@@ -314,9 +314,9 @@ fn validate(pattern: &MetaTemplate) -> Result<(), ParseError> {
                             Op::Subtree { .. } => {}
                         }
                         false
-                    }) {
-                        return Err(ParseError::RepetitionEmptyTokenTree);
-                    }
+                    })
+                {
+                    return Err(ParseError::RepetitionEmptyTokenTree);
                 }
                 validate(subtree)?
             }
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index 61b2a4955..04c0d3e75 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -213,7 +213,7 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul
     Ok(res)
 }
 
-fn eat_fragment_kind<'a>(src: &mut TtIter<'a>, mode: Mode) -> Result<Option<SmolStr>, ParseError> {
+fn eat_fragment_kind(src: &mut TtIter<'_>, mode: Mode) -> Result<Option<SmolStr>, ParseError> {
     if let Mode::Pattern = mode {
         src.expect_char(':').map_err(|()| err!("bad fragment specifier 1"))?;
         let ident = src.expect_ident().map_err(|()| err!("bad fragment specifier 1"))?;
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index b11172caf..978c75747 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -243,8 +243,7 @@ trait TokenConvertor {
     type Token: SrcToken;
 
     fn go(&mut self) -> tt::Subtree {
-        let mut subtree = tt::Subtree::default();
-        subtree.delimiter = None;
+        let mut subtree = tt::Subtree { delimiter: None, ..Default::default() };
         while self.peek().is_some() {
             self.collect_leaf(&mut subtree.token_trees);
         }
@@ -506,7 +505,7 @@ impl TokenConvertor for Convertor {
 
     fn peek(&self) -> Option<Self::Token> {
         if let Some((punct, mut offset)) = self.punct_offset.clone() {
-            offset = offset + TextSize::of('.');
+            offset += TextSize::of('.');
             if usize::from(offset) < punct.text().len() {
                 return Some(SynToken::Punch(punct, offset));
             }
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs
index 99a8d250b..bd54f2442 100644
--- a/crates/mbe/src/tt_iter.rs
+++ b/crates/mbe/src/tt_iter.rs
@@ -138,7 +138,7 @@ impl<'a> TtIter<'a> {
             }
         }
         self.inner = self.inner.as_slice()[res.len()..].iter();
-        if res.len() == 0 && err.is_none() {
+        if res.is_empty() && err.is_none() {
             err = Some(err!("no tokens consumed"));
         }
         let res = match res.len() {
diff --git a/crates/parser/src/grammar/expressions/atom.rs b/crates/parser/src/grammar/expressions/atom.rs
index 269f223e6..abdfca1fe 100644
--- a/crates/parser/src/grammar/expressions/atom.rs
+++ b/crates/parser/src/grammar/expressions/atom.rs
@@ -252,12 +252,10 @@ fn closure_expr(p: &mut Parser) -> CompletedMarker {
         // test lambda_ret_block
         // fn main() { || -> i32 { 92 }(); }
         block_expr(p);
+    } else if p.at_ts(EXPR_FIRST) {
+        expr(p);
     } else {
-        if p.at_ts(EXPR_FIRST) {
-            expr(p);
-        } else {
-            p.error("expected expression");
-        }
+        p.error("expected expression");
     }
     m.complete(p, CLOSURE_EXPR)
 }
diff --git a/crates/proc_macro_api/src/msg.rs b/crates/proc_macro_api/src/msg.rs
index f525df152..14eed4289 100644
--- a/crates/proc_macro_api/src/msg.rs
+++ b/crates/proc_macro_api/src/msg.rs
@@ -92,7 +92,7 @@ fn read_json<'a>(
 
         // Some ill behaved macro try to use stdout for debugging
         // We ignore it here
-        if !buf.starts_with("{") {
+        if !buf.starts_with('{') {
             log::error!("proc-macro tried to print : {}", buf);
             continue;
         }
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index ae78fd4f6..c33cdb740 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -92,6 +92,7 @@ config_data! {
         checkOnSave_overrideCommand: Option<Vec<String>> = "null",
 
         /// Whether to add argument snippets when completing functions.
+        /// Only applies when `#rust-analyzer.completion.addCallParenthesis#` is set.
         completion_addCallArgumentSnippets: bool = "true",
         /// Whether to add parenthesis when completing functions.
         completion_addCallParenthesis: bool      = "true",
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 456744603..49ee4b922 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -1640,7 +1640,7 @@ fn run_rustfmt(
                     .into());
                 }
 
-                let frange = from_proto::file_range(&snap, text_document.clone(), range)?;
+                let frange = from_proto::file_range(&snap, text_document, range)?;
                 let start_line = line_index.index.line_col(frange.range.start()).line;
                 let end_line = line_index.index.line_col(frange.range.end()).line;
 
diff --git a/crates/syntax/src/parsing/reparsing.rs b/crates/syntax/src/parsing/reparsing.rs
index 4ad50ab72..304f47b3d 100644
--- a/crates/syntax/src/parsing/reparsing.rs
+++ b/crates/syntax/src/parsing/reparsing.rs
@@ -36,8 +36,8 @@ pub(crate) fn incremental_reparse(
     None
 }
 
-fn reparse_token<'node>(
-    root: &'node SyntaxNode,
+fn reparse_token(
+    root: &SyntaxNode,
     edit: &Indel,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     let prev_token = root.covering_element(edit.delete).as_token()?.clone();
@@ -84,8 +84,8 @@ fn reparse_token<'node>(
     }
 }
 
-fn reparse_block<'node>(
-    root: &'node SyntaxNode,
+fn reparse_block(
+    root: &SyntaxNode,
     edit: &Indel,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     let (node, reparser) = find_reparsable_node(root, edit.delete)?;
diff --git a/crates/syntax/src/tests.rs b/crates/syntax/src/tests.rs
index 45f3c800f..9f2426171 100644
--- a/crates/syntax/src/tests.rs
+++ b/crates/syntax/src/tests.rs
@@ -236,7 +236,7 @@ where
         }
     });
     dir_tests(&test_data_dir(), err_paths, "rast", |text, path| {
-        if let Ok(_) = f(text) {
+        if f(text).is_ok() {
             panic!("'{:?}' successfully parsed when it should have errored", path);
         } else {
             "ERROR\n".to_owned()
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index bd017567c..ac5a9509d 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -238,14 +238,9 @@ fn extract_line_annotations(mut line: &str) -> Vec<LineAnnotation> {
     let mut res = Vec::new();
     let mut offset: TextSize = 0.into();
     let marker: fn(char) -> bool = if line.contains('^') { |c| c == '^' } else { |c| c == '|' };
-    loop {
-        match line.find(marker) {
-            Some(idx) => {
-                offset += TextSize::try_from(idx).unwrap();
-                line = &line[idx..];
-            }
-            None => break,
-        };
+    while let Some(idx) = line.find(marker) {
+        offset += TextSize::try_from(idx).unwrap();
+        line = &line[idx..];
 
         let mut len = line.chars().take_while(|&it| it == '^').count();
         let mut continuation = false;