Fix some more basic clippy lints

crates/ide_db/src/assists.rs

@@ -52,12 +52,12 @@ impl AssistKind {
 
         match self {
             AssistKind::None | AssistKind::Generate => true,
-            AssistKind::Refactor => match other {
+            AssistKind::Refactor => matches!(
+                other,
                 AssistKind::RefactorExtract
-                | AssistKind::RefactorInline
-                | AssistKind::RefactorRewrite => true,
-                _ => false,
-            },
+                    | AssistKind::RefactorInline
+                    | AssistKind::RefactorRewrite
+            ),
             _ => false,
         }
     }

crates/ide_db/src/call_info.rs

@@ -166,7 +166,7 @@ impl ActiveParameter {
 
         let idx = active_parameter?;
         let mut params = signature.params(sema.db);
-        if !(idx < params.len()) {
+        if params.len() <= idx {
             cov_mark::hit!(too_many_arguments);
             return None;
         }

crates/ide_db/src/defs.rs

@@ -153,7 +153,7 @@ impl NameClass {
                                         path_segment.name_ref()
                                     },
                                     PathSegmentKind::Name(name_ref) => Some(name_ref),
-                                    _ => return None,
+                                    _ => None,
                                 }
                             })
                             .and_then(|name_ref| NameRefClass::classify(sema, &name_ref))?;
@@ -341,7 +341,7 @@ impl NameRefClass {
                             hir::AssocItem::TypeAlias(it) => Some(*it),
                             _ => None,
                         })
-                        .find(|alias| &alias.name(sema.db).to_string() == &name_ref.text())
+                        .find(|alias| alias.name(sema.db).to_string() == name_ref.text())
                     {
                         return Some(NameRefClass::Definition(Definition::ModuleDef(
                             ModuleDef::TypeAlias(ty),

crates/ide_db/src/helpers/insert_use.rs

@@ -181,7 +181,7 @@ enum ImportGranularityGuess {
 }
 
 /// Insert an import path into the given file/node. A `merge` value of none indicates that no import merging is allowed to occur.
-pub fn insert_use<'a>(scope: &ImportScope, path: ast::Path, cfg: &InsertUseConfig) {
+pub fn insert_use(scope: &ImportScope, path: ast::Path, cfg: &InsertUseConfig) {
     let _p = profile::span("insert_use");
     let mut mb = match cfg.granularity {
         ImportGranularity::Crate => Some(MergeBehavior::Crate),

crates/ide_db/src/helpers/merge_imports.rs

@@ -162,7 +162,7 @@ fn recursive_merge(
             }
             Err(_)
                 if merge == MergeBehavior::Module
-                    && use_trees.len() > 0
+                    && !use_trees.is_empty()
                     && rhs_t.use_tree_list().is_some() =>
             {
                 return None

crates/ide_db/src/source_change.rs

@@ -3,10 +3,7 @@
 //!
 //! It can be viewed as a dual for `Change`.
 
-use std::{
-    collections::hash_map::Entry,
-    iter::{self, FromIterator},
-};
+use std::{collections::hash_map::Entry, iter};
 
 use base_db::{AnchoredPathBuf, FileId};
 use rustc_hash::FxHashMap;
@@ -32,7 +29,7 @@ impl SourceChange {
 
     pub fn from_text_edit(file_id: FileId, edit: TextEdit) -> Self {
         SourceChange {
-            source_file_edits: FxHashMap::from_iter(iter::once((file_id, edit))),
+            source_file_edits: iter::once((file_id, edit)).collect(),
             ..Default::default()
         }
     }

crates/ide_db/src/ty_filter.rs

@@ -26,7 +26,7 @@ impl TryEnum {
             _ => return None,
         };
         TryEnum::ALL.iter().find_map(|&var| {
-            if &enum_.name(sema.db).to_string() == var.type_name() {
+            if enum_.name(sema.db).to_string() == var.type_name() {
                 return Some(var);
             }
             None

crates/parser/src/grammar/params.rs

@@ -105,14 +105,12 @@ fn param(p: &mut Parser, m: Marker, flavor: Flavor) -> Variadic {
             patterns::pattern(p);
             if variadic_param(p) {
                 res = Variadic(true)
+            } else if p.at(T![:]) {
+                types::ascription(p)
             } else {
-                if p.at(T![:]) {
-                    types::ascription(p)
-                } else {
-                    // test_err missing_fn_param_type
-                    // fn f(x y: i32, z, t: i32) {}
-                    p.error("missing type for function parameter")
-                }
+                // test_err missing_fn_param_type
+                // fn f(x y: i32, z, t: i32) {}
+                p.error("missing type for function parameter")
             }
         }
         // test value_parameters_no_patterns
@@ -131,12 +129,10 @@ fn param(p: &mut Parser, m: Marker, flavor: Flavor) -> Variadic {
                 patterns::pattern_single(p);
                 if variadic_param(p) {
                     res = Variadic(true)
+                } else if p.at(T![:]) {
+                    types::ascription(p)
                 } else {
-                    if p.at(T![:]) {
-                        types::ascription(p)
-                    } else {
-                        p.error("missing type for function parameter")
-                    }
+                    p.error("missing type for function parameter")
                 }
             } else {
                 types::type_(p);

crates/syntax/src/ast/node_ext.rs

@@ -91,7 +91,7 @@ impl ast::Expr {
                                         | ast::Effect::Const(_)
                                 )
                             }
-                            ast::Expr::ClosureExpr(__) => true,
+                            ast::Expr::ClosureExpr(_) => true,
                             _ => false,
                         };
                         cb(expr);