Merge #8135

8135: more clippy::{perf, complexity, style} fixes r=Veykril a=matthiaskrgr



Co-authored-by: Matthias Krüger <[email protected]>

39 files changed, 130 insertions, 168 deletions

diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
index d0def2181..e9e8dfc2e 100644
--- a/crates/base_db/src/input.rs
+++ b/crates/base_db/src/input.rs
@@ -410,7 +410,7 @@ impl CrateId {
 
 impl CrateData {
     fn add_dep(&mut self, name: CrateName, crate_id: CrateId) {
-        self.dependencies.push(Dependency { name, crate_id })
+        self.dependencies.push(Dependency { crate_id, name })
     }
 }
 
diff --git a/crates/cfg/src/dnf.rs b/crates/cfg/src/dnf.rs
index 30f4bcdf7..75ded9aa1 100644
--- a/crates/cfg/src/dnf.rs
+++ b/crates/cfg/src/dnf.rs
@@ -255,9 +255,9 @@ impl Builder {
 fn make_dnf(expr: CfgExpr) -> CfgExpr {
     match expr {
         CfgExpr::Invalid | CfgExpr::Atom(_) | CfgExpr::Not(_) => expr,
-        CfgExpr::Any(e) => CfgExpr::Any(e.into_iter().map(|expr| make_dnf(expr)).collect()),
+        CfgExpr::Any(e) => CfgExpr::Any(e.into_iter().map(make_dnf).collect()),
         CfgExpr::All(e) => {
-            let e = e.into_iter().map(|expr| make_nnf(expr)).collect::<Vec<_>>();
+            let e = e.into_iter().map(make_nnf).collect::<Vec<_>>();
 
             CfgExpr::Any(distribute_conj(&e))
         }
@@ -300,8 +300,8 @@ fn distribute_conj(conj: &[CfgExpr]) -> Vec<CfgExpr> {
 fn make_nnf(expr: CfgExpr) -> CfgExpr {
     match expr {
         CfgExpr::Invalid | CfgExpr::Atom(_) => expr,
-        CfgExpr::Any(expr) => CfgExpr::Any(expr.into_iter().map(|expr| make_nnf(expr)).collect()),
-        CfgExpr::All(expr) => CfgExpr::All(expr.into_iter().map(|expr| make_nnf(expr)).collect()),
+        CfgExpr::Any(expr) => CfgExpr::Any(expr.into_iter().map(make_nnf).collect()),
+        CfgExpr::All(expr) => CfgExpr::All(expr.into_iter().map(make_nnf).collect()),
         CfgExpr::Not(operand) => match *operand {
             CfgExpr::Invalid | CfgExpr::Atom(_) => CfgExpr::Not(operand.clone()), // Original negated expr
             CfgExpr::Not(expr) => {
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index e34be7e42..44eaeffb9 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -213,7 +213,7 @@ impl Crate {
                 Some(TokenTree::Leaf(Leaf::Literal(Literal{ref text, ..}))) => Some(text),
                 _ => None
             }
-        }).flat_map(|t| t).next();
+        }).flatten().next();
 
         doc_url.map(|s| s.trim_matches('"').trim_end_matches('/').to_owned() + "/")
     }
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 2c10f46d8..52a2bce9b 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -638,7 +638,7 @@ fn collect_attrs(
     owner: &dyn ast::AttrsOwner,
 ) -> impl Iterator<Item = Either<ast::Attr, ast::Comment>> {
     let (inner_attrs, inner_docs) = inner_attributes(owner.syntax())
-        .map_or((None, None), |(attrs, docs)| ((Some(attrs), Some(docs))));
+        .map_or((None, None), |(attrs, docs)| (Some(attrs), Some(docs)));
 
     let outer_attrs = owner.attrs().filter(|attr| attr.excl_token().is_none());
     let attrs = outer_attrs
diff --git a/crates/hir_def/src/resolver.rs b/crates/hir_def/src/resolver.rs
index 4a2d1c087..04ea9c5d7 100644
--- a/crates/hir_def/src/resolver.rs
+++ b/crates/hir_def/src/resolver.rs
@@ -472,7 +472,7 @@ impl Scope {
             }
             Scope::ExprScope(scope) => {
                 if let Some((label, name)) = scope.expr_scopes.label(scope.scope_id) {
-                    f(name.clone(), ScopeDef::Label(label))
+                    f(name, ScopeDef::Label(label))
                 }
                 scope.expr_scopes.entries(scope.scope_id).iter().for_each(|e| {
                     f(e.name().clone(), ScopeDef::Local(e.pat()));
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 2748e25cf..fc73e435b 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -173,7 +173,7 @@ fn macro_arg_text(db: &dyn AstDatabase, id: MacroCallId) -> Option<GreenNode> {
     };
     let loc = db.lookup_intern_macro(id);
     let arg = loc.kind.arg(db)?;
-    Some(arg.green().to_owned())
+    Some(arg.green())
 }
 
 fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
index 43de9edd6..0aeea48d5 100644
--- a/crates/hir_expand/src/name.rs
+++ b/crates/hir_expand/src/name.rs
@@ -48,9 +48,8 @@ impl Name {
 
     /// Resolve a name from the text of token.
     fn resolve(raw_text: &str) -> Name {
-        let raw_start = "r#";
-        if raw_text.starts_with(raw_start) {
-            Name::new_text(SmolStr::new(&raw_text[raw_start.len()..]))
+        if let Some(text) = raw_text.strip_prefix("r#") {
+            Name::new_text(SmolStr::new(text))
         } else {
             Name::new_text(raw_text.into())
         }
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index befa0d69b..ec491648f 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -38,7 +38,7 @@ impl<'a> InferenceContext<'a> {
         let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
         let (pre, post) = match ellipsis {
             Some(idx) => subpats.split_at(idx),
-            None => (&subpats[..], &[][..]),
+            None => (subpats, &[][..]),
         };
         let post_idx_offset = field_tys.iter().count() - post.len();
 
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index cbbb535e5..c914a3b8e 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -946,8 +946,7 @@ pub(crate) fn trait_environment_query(
         let substs = Substitution::type_params(db, trait_id);
         let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
         let pred = WhereClause::Implemented(trait_ref);
-        let program_clause: chalk_ir::ProgramClause<Interner> =
-            pred.clone().to_chalk(db).cast(&Interner);
+        let program_clause: chalk_ir::ProgramClause<Interner> = pred.to_chalk(db).cast(&Interner);
         clauses.push(program_clause.into_from_env_clause(&Interner));
     }
 
diff --git a/crates/ide/src/extend_selection.rs b/crates/ide/src/extend_selection.rs
index e187243cb..5201ce587 100644
--- a/crates/ide/src/extend_selection.rs
+++ b/crates/ide/src/extend_selection.rs
@@ -263,11 +263,10 @@ fn extend_list_item(node: &SyntaxNode) -> Option<TextRange> {
     ) -> Option<SyntaxToken> {
         node.siblings_with_tokens(dir)
             .skip(1)
-            .skip_while(|node| match node {
-                NodeOrToken::Node(_) => false,
-                NodeOrToken::Token(it) => is_single_line_ws(it),
+            .find(|node| match node {
+                NodeOrToken::Node(_) => true,
+                NodeOrToken::Token(it) => !is_single_line_ws(it),
             })
-            .next()
             .and_then(|it| it.into_token())
             .filter(|node| node.kind() == delimiter_kind)
     }
diff --git a/crates/ide_assists/src/handlers/convert_comment_block.rs b/crates/ide_assists/src/handlers/convert_comment_block.rs
index cdc45fc42..9dc3ee28f 100644
--- a/crates/ide_assists/src/handlers/convert_comment_block.rs
+++ b/crates/ide_assists/src/handlers/convert_comment_block.rs
@@ -1,5 +1,4 @@
 use itertools::Itertools;
-use std::convert::identity;
 use syntax::{
     ast::{
         self,
@@ -140,7 +139,7 @@ fn relevant_line_comments(comment: &ast::Comment) -> Vec<Comment> {
         .filter(|s| !skippable(s))
         .map(|not| not.into_token().and_then(Comment::cast).filter(same_prefix))
         .take_while(|opt_com| opt_com.is_some())
-        .filter_map(identity)
+        .flatten()
         .skip(1); // skip the first element so we don't duplicate it in next_comments
 
     let next_comments = comment
@@ -149,7 +148,7 @@ fn relevant_line_comments(comment: &ast::Comment) -> Vec<Comment> {
         .filter(|s| !skippable(s))
         .map(|not| not.into_token().and_then(Comment::cast).filter(same_prefix))
         .take_while(|opt_com| opt_com.is_some())
-        .filter_map(identity);
+        .flatten();
 
     let mut comments: Vec<_> = prev_comments.collect();
     comments.reverse();
diff --git a/crates/ide_assists/src/handlers/expand_glob_import.rs b/crates/ide_assists/src/handlers/expand_glob_import.rs
index 83aa11d52..98389e4f7 100644
--- a/crates/ide_assists/src/handlers/expand_glob_import.rs
+++ b/crates/ide_assists/src/handlers/expand_glob_import.rs
@@ -136,18 +136,13 @@ impl Refs {
                 .into_iter()
                 .filter(|r| {
                     if let Def::ModuleDef(ModuleDef::Trait(tr)) = r.def {
-                        if tr
-                            .items(ctx.db())
-                            .into_iter()
-                            .find(|ai| {
-                                if let AssocItem::Function(f) = *ai {
-                                    Def::ModuleDef(ModuleDef::Function(f)).is_referenced_in(ctx)
-                                } else {
-                                    false
-                                }
-                            })
-                            .is_some()
-                        {
+                        if tr.items(ctx.db()).into_iter().any(|ai| {
+                            if let AssocItem::Function(f) = ai {
+                                Def::ModuleDef(ModuleDef::Function(f)).is_referenced_in(ctx)
+                            } else {
+                                false
+                            }
+                        }) {
                             return true;
                         }
                     }
diff --git a/crates/ide_assists/src/handlers/reorder_impl.rs b/crates/ide_assists/src/handlers/reorder_impl.rs
index edf4b0bfe..f976e73ad 100644
--- a/crates/ide_assists/src/handlers/reorder_impl.rs
+++ b/crates/ide_assists/src/handlers/reorder_impl.rs
@@ -95,7 +95,7 @@ fn compute_method_ranks(path: &ast::Path, ctx: &AssistContext) -> Option<FxHashM
                 _ => None,
             })
             .enumerate()
-            .map(|(idx, func)| ((func.name(ctx.db()).to_string(), idx)))
+            .map(|(idx, func)| (func.name(ctx.db()).to_string(), idx))
             .collect(),
     )
 }
diff --git a/crates/ide_completion/src/patterns.rs b/crates/ide_completion/src/patterns.rs
index cf5ef07b7..d82564381 100644
--- a/crates/ide_completion/src/patterns.rs
+++ b/crates/ide_completion/src/patterns.rs
@@ -71,7 +71,7 @@ fn test_has_block_expr_parent() {
 }
 
 pub(crate) fn has_bind_pat_parent(element: SyntaxElement) -> bool {
-    element.ancestors().find(|it| it.kind() == IDENT_PAT).is_some()
+    element.ancestors().any(|it| it.kind() == IDENT_PAT)
 }
 #[test]
 fn test_has_bind_pat_parent() {
diff --git a/crates/ide_ssr/src/parsing.rs b/crates/ide_ssr/src/parsing.rs
index 5ff25cb6d..5e757e701 100644
--- a/crates/ide_ssr/src/parsing.rs
+++ b/crates/ide_ssr/src/parsing.rs
@@ -67,7 +67,7 @@ impl ParsedRule {
     ) -> Result<Vec<ParsedRule>, SsrError> {
         let raw_pattern = pattern.as_rust_code();
         let raw_template = template.map(|t| t.as_rust_code());
-        let raw_template = raw_template.as_ref().map(|s| s.as_str());
+        let raw_template = raw_template.as_deref();
         let mut builder = RuleBuilder {
             placeholders_by_stand_in: pattern.placeholders_by_stand_in(),
             rules: Vec::new(),
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs
index 1682b21b0..75d2f2eed 100644
--- a/crates/mbe/src/expander/matcher.rs
+++ b/crates/mbe/src/expander/matcher.rs
@@ -304,7 +304,7 @@ impl BindingsBuilder {
         link_nodes: &'a Vec<LinkNode<Rc<BindingKind>>>,
         nodes: &mut Vec<&'a Rc<BindingKind>>,
     ) {
-        link_nodes.into_iter().for_each(|it| match it {
+        link_nodes.iter().for_each(|it| match it {
             LinkNode::Node(it) => nodes.push(it),
             LinkNode::Parent { idx, len } => self.collect_nodes_ref(*idx, *len, nodes),
         });
@@ -713,10 +713,9 @@ fn match_meta_var(kind: &str, input: &mut TtIter) -> ExpandResult<Option<Fragmen
                     .map(|ident| Some(tt::Leaf::from(ident.clone()).into()))
                     .map_err(|()| err!("expected ident")),
                 "tt" => input.expect_tt().map(Some).map_err(|()| err!()),
-                "lifetime" => input
-                    .expect_lifetime()
-                    .map(|tt| Some(tt))
-                    .map_err(|()| err!("expected lifetime")),
+                "lifetime" => {
+                    input.expect_lifetime().map(Some).map_err(|()| err!("expected lifetime"))
+                }
                 "literal" => {
                     let neg = input.eat_char('-');
                     input
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index 33b85e23d..e74f8cf3f 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -356,6 +356,6 @@ impl<T> ExpandResult<T> {
 
 impl<T: Default> From<Result<T, ExpandError>> for ExpandResult<T> {
     fn from(result: Result<T, ExpandError>) -> Self {
-        result.map_or_else(|e| Self::only_err(e), |it| Self::ok(it))
+        result.map_or_else(Self::only_err, Self::ok)
     }
 }
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index c88387653..61b2a4955 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -57,7 +57,7 @@ impl<'a> Iterator for OpDelimitedIter<'a> {
 
     fn size_hint(&self) -> (usize, Option<usize>) {
         let len = self.inner.len() + if self.delimited.is_some() { 2 } else { 0 };
-        let remain = len.checked_sub(self.idx).unwrap_or(0);
+        let remain = len.saturating_sub(self.idx);
         (remain, Some(remain))
     }
 }
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index 8bba3d3d5..9d433b3b0 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -362,7 +362,7 @@ trait TokenConvertor {
             if let Some((kind, closed)) = delim {
                 let mut subtree = tt::Subtree::default();
                 let (id, idx) = self.id_alloc().open_delim(range);
-                subtree.delimiter = Some(tt::Delimiter { kind, id });
+                subtree.delimiter = Some(tt::Delimiter { id, kind });
 
                 while self.peek().map(|it| it.kind() != closed).unwrap_or(false) {
                     self.collect_leaf(&mut subtree.token_trees);
diff --git a/crates/mbe/src/tests/expand.rs b/crates/mbe/src/tests/expand.rs
index 2cce62781..8951f3813 100644
--- a/crates/mbe/src/tests/expand.rs
+++ b/crates/mbe/src/tests/expand.rs
@@ -1225,8 +1225,7 @@ macro_rules! m {
     )
     .expand_statements(r#"m!(C("0"))"#)
     .descendants()
-    .find(|token| token.kind() == ERROR)
-    .is_some());
+    .any(|token| token.kind() == ERROR));
 }
 
 #[test]
diff --git a/crates/project_model/src/build_data.rs b/crates/project_model/src/build_data.rs
index 728a258ea..f7050be4e 100644
--- a/crates/project_model/src/build_data.rs
+++ b/crates/project_model/src/build_data.rs
@@ -137,60 +137,53 @@ fn collect_from_workspace(
     let stdout = BufReader::new(child_stdout);
 
     let mut res = BuildDataMap::default();
-    for message in cargo_metadata::Message::parse_stream(stdout) {
-        if let Ok(message) = message {
-            match message {
-                Message::BuildScriptExecuted(BuildScript {
-                    package_id,
-                    out_dir,
-                    cfgs,
-                    env,
-                    ..
-                }) => {
-                    let cfgs = {
-                        let mut acc = Vec::new();
-                        for cfg in cfgs {
-                            match cfg.parse::<CfgFlag>() {
-                                Ok(it) => acc.push(it),
-                                Err(err) => {
-                                    anyhow::bail!("invalid cfg from cargo-metadata: {}", err)
-                                }
-                            };
-                        }
-                        acc
-                    };
-                    let res = res.entry(package_id.repr.clone()).or_default();
-                    // cargo_metadata crate returns default (empty) path for
-                    // older cargos, which is not absolute, so work around that.
-                    if !out_dir.as_str().is_empty() {
-                        let out_dir = AbsPathBuf::assert(PathBuf::from(out_dir.into_os_string()));
-                        res.out_dir = Some(out_dir);
-                        res.cfgs = cfgs;
+    for message in cargo_metadata::Message::parse_stream(stdout).flatten() {
+        match message {
+            Message::BuildScriptExecuted(BuildScript {
+                package_id, out_dir, cfgs, env, ..
+            }) => {
+                let cfgs = {
+                    let mut acc = Vec::new();
+                    for cfg in cfgs {
+                        match cfg.parse::<CfgFlag>() {
+                            Ok(it) => acc.push(it),
+                            Err(err) => {
+                                anyhow::bail!("invalid cfg from cargo-metadata: {}", err)
+                            }
+                        };
                     }
-
-                    res.envs = env;
+                    acc
+                };
+                let res = res.entry(package_id.repr.clone()).or_default();
+                // cargo_metadata crate returns default (empty) path for
+                // older cargos, which is not absolute, so work around that.
+                if !out_dir.as_str().is_empty() {
+                    let out_dir = AbsPathBuf::assert(PathBuf::from(out_dir.into_os_string()));
+                    res.out_dir = Some(out_dir);
+                    res.cfgs = cfgs;
                 }
-                Message::CompilerArtifact(message) => {
-                    progress(format!("metadata {}", message.target.name));
-
-                    if message.target.kind.contains(&"proc-macro".to_string()) {
-                        let package_id = message.package_id;
-                        // Skip rmeta file
-                        if let Some(filename) = message.filenames.iter().find(|name| is_dylib(name))
-                        {
-                            let filename = AbsPathBuf::assert(PathBuf::from(&filename));
-                            let res = res.entry(package_id.repr.clone()).or_default();
-                            res.proc_macro_dylib_path = Some(filename);
-                        }
+
+                res.envs = env;
+            }
+            Message::CompilerArtifact(message) => {
+                progress(format!("metadata {}", message.target.name));
+
+                if message.target.kind.contains(&"proc-macro".to_string()) {
+                    let package_id = message.package_id;
+                    // Skip rmeta file
+                    if let Some(filename) = message.filenames.iter().find(|name| is_dylib(name)) {
+                        let filename = AbsPathBuf::assert(PathBuf::from(&filename));
+                        let res = res.entry(package_id.repr.clone()).or_default();
+                        res.proc_macro_dylib_path = Some(filename);
                     }
                 }
-                Message::CompilerMessage(message) => {
-                    progress(message.target.name.clone());
-                }
-                Message::BuildFinished(_) => {}
-                Message::TextLine(_) => {}
-                _ => {}
             }
+            Message::CompilerMessage(message) => {
+                progress(message.target.name.clone());
+            }
+            Message::BuildFinished(_) => {}
+            Message::TextLine(_) => {}
+            _ => {}
         }
     }
 
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 984790d35..c63a0eaea 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -242,11 +242,8 @@ impl GlobalState {
                                 }
                                 BuildDataProgress::End(collector) => {
                                     self.fetch_build_data_completed();
-                                    let workspaces = (*self.workspaces)
-                                        .clone()
-                                        .into_iter()
-                                        .map(|it| Ok(it))
-                                        .collect();
+                                    let workspaces =
+                                        (*self.workspaces).clone().into_iter().map(Ok).collect();
                                     self.switch_workspaces(workspaces, Some(collector));
                                     (Some(Progress::End), None)
                                 }
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index aa8504c3d..76fdbcddd 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -237,7 +237,7 @@ impl GlobalState {
             None => None,
         };
 
-        if &*self.workspaces == &workspaces && self.workspace_build_data == workspace_build_data {
+        if *self.workspaces == workspaces && self.workspace_build_data == workspace_build_data {
             return;
         }
 
diff --git a/crates/rust-analyzer/tests/rust-analyzer/support.rs b/crates/rust-analyzer/tests/rust-analyzer/support.rs
index cd0c91481..95bf26f01 100644
--- a/crates/rust-analyzer/tests/rust-analyzer/support.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/support.rs
@@ -54,7 +54,7 @@ impl<'a> Project<'a> {
     }
 
     pub(crate) fn server(self) -> Server {
-        let tmp_dir = self.tmp_dir.unwrap_or_else(|| TestDir::new());
+        let tmp_dir = self.tmp_dir.unwrap_or_else(TestDir::new);
         static INIT: Once = Once::new();
         INIT.call_once(|| {
             env_logger::builder().is_test(true).parse_env("RA_LOG").try_init().unwrap();
diff --git a/crates/syntax/src/algo.rs b/crates/syntax/src/algo.rs
index 82ebf9037..a153a9e1c 100644
--- a/crates/syntax/src/algo.rs
+++ b/crates/syntax/src/algo.rs
@@ -567,7 +567,7 @@ impl<'a> SyntaxRewriter<'a> {
 
 fn element_to_green(element: SyntaxElement) -> NodeOrToken<rowan::GreenNode, rowan::GreenToken> {
     match element {
-        NodeOrToken::Node(it) => NodeOrToken::Node(it.green().to_owned()),
+        NodeOrToken::Node(it) => NodeOrToken::Node(it.green()),
         NodeOrToken::Token(it) => NodeOrToken::Token(it.green().to_owned()),
     }
 }
@@ -625,7 +625,7 @@ fn position_of_child(parent: &SyntaxNode, child: SyntaxElement) -> usize {
 
 fn to_green_element(element: SyntaxElement) -> NodeOrToken<rowan::GreenNode, rowan::GreenToken> {
     match element {
-        NodeOrToken::Node(it) => it.green().to_owned().into(),
+        NodeOrToken::Node(it) => it.green().into(),
         NodeOrToken::Token(it) => it.green().to_owned().into(),
     }
 }
diff --git a/crates/syntax/src/ast/edit.rs b/crates/syntax/src/ast/edit.rs
index 64fac13a7..347862b8a 100644
--- a/crates/syntax/src/ast/edit.rs
+++ b/crates/syntax/src/ast/edit.rs
@@ -333,8 +333,7 @@ impl ast::Use {
             .and_then(ast::Whitespace::cast);
         if let Some(next_ws) = next_ws {
             let ws_text = next_ws.syntax().text();
-            if ws_text.starts_with('\n') {
-                let rest = &ws_text[1..];
+            if let Some(rest) = ws_text.strip_prefix('\n') {
                 if rest.is_empty() {
                     res.delete(next_ws.syntax())
                 } else {
@@ -462,8 +461,7 @@ impl ast::MatchArmList {
         let end = if let Some(comma) = start
             .siblings_with_tokens(Direction::Next)
             .skip(1)
-            .skip_while(|it| it.kind().is_trivia())
-            .next()
+            .find(|it| !it.kind().is_trivia())
             .filter(|it| it.kind() == T![,])
         {
             comma
@@ -597,7 +595,7 @@ impl IndentLevel {
     pub fn from_node(node: &SyntaxNode) -> IndentLevel {
         match node.first_token() {
             Some(it) => Self::from_token(&it),
-            None => return IndentLevel(0),
+            None => IndentLevel(0),
         }
     }
 
diff --git a/crates/syntax/src/ast/expr_ext.rs b/crates/syntax/src/ast/expr_ext.rs
index 636ce166d..6317d84ba 100644
--- a/crates/syntax/src/ast/expr_ext.rs
+++ b/crates/syntax/src/ast/expr_ext.rs
@@ -11,16 +11,16 @@ impl ast::AttrsOwner for ast::Expr {}
 
 impl ast::Expr {
     pub fn is_block_like(&self) -> bool {
-        match self {
+        matches!(
+            self,
             ast::Expr::IfExpr(_)
-            | ast::Expr::LoopExpr(_)
-            | ast::Expr::ForExpr(_)
-            | ast::Expr::WhileExpr(_)
-            | ast::Expr::BlockExpr(_)
-            | ast::Expr::MatchExpr(_)
-            | ast::Expr::EffectExpr(_) => true,
-            _ => false,
-        }
+                | ast::Expr::LoopExpr(_)
+                | ast::Expr::ForExpr(_)
+                | ast::Expr::WhileExpr(_)
+                | ast::Expr::BlockExpr(_)
+                | ast::Expr::MatchExpr(_)
+                | ast::Expr::EffectExpr(_)
+        )
     }
 
     pub fn name_ref(&self) -> Option<ast::NameRef> {
@@ -151,20 +151,20 @@ pub enum BinOp {
 
 impl BinOp {
     pub fn is_assignment(self) -> bool {
-        match self {
+        matches!(
+            self,
             BinOp::Assignment
-            | BinOp::AddAssign
-            | BinOp::DivAssign
-            | BinOp::MulAssign
-            | BinOp::RemAssign
-            | BinOp::ShrAssign
-            | BinOp::ShlAssign
-            | BinOp::SubAssign
-            | BinOp::BitOrAssign
-            | BinOp::BitAndAssign
-            | BinOp::BitXorAssign => true,
-            _ => false,
-        }
+                | BinOp::AddAssign
+                | BinOp::DivAssign
+                | BinOp::MulAssign
+                | BinOp::RemAssign
+                | BinOp::ShrAssign
+                | BinOp::ShlAssign
+                | BinOp::SubAssign
+                | BinOp::BitOrAssign
+                | BinOp::BitAndAssign
+                | BinOp::BitXorAssign
+        )
     }
 }
 
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index 810c8d4c8..7049affd9 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -532,7 +532,7 @@ fn ast_from_text<N: AstNode>(text: &str) -> N {
 }
 
 fn unroot(n: SyntaxNode) -> SyntaxNode {
-    SyntaxNode::new_root(n.green().to_owned())
+    SyntaxNode::new_root(n.green())
 }
 
 pub mod tokens {
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index 42a7b9c2a..bdf907a21 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -58,10 +58,7 @@ impl From<ast::MacroDef> for Macro {
 
 impl AstNode for Macro {
     fn can_cast(kind: SyntaxKind) -> bool {
-        match kind {
-            SyntaxKind::MACRO_RULES | SyntaxKind::MACRO_DEF => true,
-            _ => false,
-        }
+        matches!(kind, SyntaxKind::MACRO_RULES | SyntaxKind::MACRO_DEF)
     }
     fn cast(syntax: SyntaxNode) -> Option<Self> {
         let res = match syntax.kind() {
@@ -462,10 +459,8 @@ impl ast::FieldExpr {
     pub fn field_access(&self) -> Option<FieldKind> {
         if let Some(nr) = self.name_ref() {
             Some(FieldKind::Name(nr))
-        } else if let Some(tok) = self.index_token() {
-            Some(FieldKind::Index(tok))
         } else {
-            None
+            self.index_token().map(FieldKind::Index)
         }
     }
 }
@@ -482,16 +477,10 @@ impl ast::SlicePat {
         let prefix = args
             .peeking_take_while(|p| match p {
                 ast::Pat::RestPat(_) => false,
-                ast::Pat::IdentPat(bp) => match bp.pat() {
-                    Some(ast::Pat::RestPat(_)) => false,
-                    _ => true,
-                },
+                ast::Pat::IdentPat(bp) => !matches!(bp.pat(), Some(ast::Pat::RestPat(_))),
                 ast::Pat::RefPat(rp) => match rp.pat() {
                     Some(ast::Pat::RestPat(_)) => false,
-                    Some(ast::Pat::IdentPat(bp)) => match bp.pat() {
-                        Some(ast::Pat::RestPat(_)) => false,
-                        _ => true,
-                    },
+                    Some(ast::Pat::IdentPat(bp)) => !matches!(bp.pat(), Some(ast::Pat::RestPat(_))),
                     _ => true,
                 },
                 _ => true,
diff --git a/crates/syntax/src/ast/token_ext.rs b/crates/syntax/src/ast/token_ext.rs
index 6c242d126..090282d28 100644
--- a/crates/syntax/src/ast/token_ext.rs
+++ b/crates/syntax/src/ast/token_ext.rs
@@ -494,9 +494,8 @@ pub trait HasFormatSpecifier: AstToken {
                 }
                 _ => {
                     while let Some((_, Ok(next_char))) = chars.peek() {
-                        match next_char {
-                            '{' => break,
-                            _ => {}
+                        if next_char == &'{' {
+                            break;
                         }
                         chars.next();
                     }
diff --git a/crates/syntax/src/fuzz.rs b/crates/syntax/src/fuzz.rs
index fbb97aa27..aa84239d2 100644
--- a/crates/syntax/src/fuzz.rs
+++ b/crates/syntax/src/fuzz.rs
@@ -43,7 +43,7 @@ impl CheckReparse {
             TextRange::at(delete_start.try_into().unwrap(), delete_len.try_into().unwrap());
         let edited_text =
             format!("{}{}{}", &text[..delete_start], &insert, &text[delete_start + delete_len..]);
-        let edit = Indel { delete, insert };
+        let edit = Indel { insert, delete };
         Some(CheckReparse { text, edit, edited_text })
     }
 
diff --git a/crates/syntax/src/validation.rs b/crates/syntax/src/validation.rs
index 3e216fb70..bbe802174 100644
--- a/crates/syntax/src/validation.rs
+++ b/crates/syntax/src/validation.rs
@@ -297,7 +297,7 @@ fn validate_path_keywords(segment: ast::PathSegment, errors: &mut Vec<SyntaxErro
                 }
             };
         }
-        return None;
+        None
     }
 
     fn all_supers(path: &ast::Path) -> bool {
@@ -314,7 +314,7 @@ fn validate_path_keywords(segment: ast::PathSegment, errors: &mut Vec<SyntaxErro
             return all_supers(subpath);
         }
 
-        return true;
+        true
     }
 }
 
diff --git a/crates/tt/src/lib.rs b/crates/tt/src/lib.rs
index 9d9a01e30..bed44d600 100644
--- a/crates/tt/src/lib.rs
+++ b/crates/tt/src/lib.rs
@@ -239,9 +239,8 @@ impl Subtree {
 
         let mut res = String::new();
         res.push_str(delim.0);
-        let mut iter = self.token_trees.iter();
         let mut last = None;
-        while let Some(child) = iter.next() {
+        for child in &self.token_trees {
             let s = match child {
                 TokenTree::Leaf(it) => {
                     let s = match it {
diff --git a/xtask/src/codegen/gen_assists_docs.rs b/xtask/src/codegen/gen_assists_docs.rs
index 158680993..c91716409 100644
--- a/xtask/src/codegen/gen_assists_docs.rs
+++ b/xtask/src/codegen/gen_assists_docs.rs
@@ -154,8 +154,8 @@ fn hide_hash_comments(text: &str) -> String {
 fn reveal_hash_comments(text: &str) -> String {
     text.split('\n') // want final newline
         .map(|it| {
-            if it.starts_with("# ") {
-                &it[2..]
+            if let Some(stripped) = it.strip_prefix("# ") {
+                stripped
             } else if it == "#" {
                 ""
             } else {
diff --git a/xtask/src/codegen/gen_parser_tests.rs b/xtask/src/codegen/gen_parser_tests.rs
index 096590653..2fecb9b5b 100644
--- a/xtask/src/codegen/gen_parser_tests.rs
+++ b/xtask/src/codegen/gen_parser_tests.rs
@@ -60,12 +60,10 @@ fn collect_tests(s: &str) -> Vec<Test> {
     let mut res = Vec::new();
     for comment_block in extract_comment_blocks(s) {
         let first_line = &comment_block[0];
-        let (name, ok) = if first_line.starts_with("test ") {
-            let name = first_line["test ".len()..].to_string();
-            (name, true)
-        } else if first_line.starts_with("test_err ") {
-            let name = first_line["test_err ".len()..].to_string();
-            (name, false)
+        let (name, ok) = if let Some(name) = first_line.strip_prefix("test ") {
+            (name.to_string(), true)
+        } else if let Some(name) = first_line.strip_prefix("test_err ") {
+            (name.to_string(), false)
         } else {
             continue;
         };
diff --git a/xtask/src/codegen/gen_syntax.rs b/xtask/src/codegen/gen_syntax.rs
index 80f26e8f5..ba4b24848 100644
--- a/xtask/src/codegen/gen_syntax.rs
+++ b/xtask/src/codegen/gen_syntax.rs
@@ -707,7 +707,7 @@ fn extract_struct_trait(node: &mut AstNodeSrc, trait_name: &str, methods: &[&str
     let mut to_remove = Vec::new();
     for (i, field) in node.fields.iter().enumerate() {
         let method_name = field.method_name().to_string();
-        if methods.iter().any(|&it| it == &method_name) {
+        if methods.iter().any(|&it| it == method_name) {
             to_remove.push(i);
         }
     }
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index 915aae71a..960927fc0 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -37,7 +37,7 @@ fn main() -> Result<()> {
     match flags.subcommand {
         flags::XtaskCmd::Help(_) => {
             println!("{}", flags::Xtask::HELP);
-            return Ok(());
+            Ok(())
         }
         flags::XtaskCmd::Install(cmd) => cmd.run(),
         flags::XtaskCmd::FuzzTests(_) => run_fuzzer(),
diff --git a/xtask/src/metrics.rs b/xtask/src/metrics.rs
index 97395738b..b0b76b8aa 100644
--- a/xtask/src/metrics.rs
+++ b/xtask/src/metrics.rs
@@ -167,7 +167,7 @@ impl Host {
 
         return Ok(Host { os, cpu, mem });
 
-        fn read_field<'a>(path: &str, field: &str) -> Result<String> {
+        fn read_field(path: &str, field: &str) -> Result<String> {
             let text = read_file(path)?;
 
             let line = text
diff --git a/xtask/src/tidy.rs b/xtask/src/tidy.rs
index 1352d1218..50d9efccd 100644
--- a/xtask/src/tidy.rs
+++ b/xtask/src/tidy.rs
@@ -193,7 +193,7 @@ https://github.blog/2015-06-08-how-to-undo-almost-anything-with-git/#redo-after-
     }
 }
 
-fn deny_clippy(path: &PathBuf, text: &String) {
+fn deny_clippy(path: &Path, text: &str) {
     let ignore = &[
         // The documentation in string literals may contain anything for its own purposes
         "ide_completion/src/generated_lint_completions.rs",