48 files changed, 132 insertions, 149 deletions

diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index 7fdd816bf..4d3a72c18 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -45,7 +45,7 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
     let trait_token =
         ctx.token_at_offset().filter(|t| t.kind() == IDENT && *t.text() != attr_name).next()?;
 
-    let annotated = attr.syntax().siblings(Direction::Next).find_map(|s| ast::Name::cast(s))?;
+    let annotated = attr.syntax().siblings(Direction::Next).find_map(ast::Name::cast)?;
     let annotated_name = annotated.syntax().text().to_string();
     let start_offset = annotated.syntax().parent()?.text_range().end();
 
@@ -62,7 +62,7 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
             .filter_map(|t| t.into_token().map(|t| t.text().clone()))
             .filter(|t| t != trait_token.text())
             .collect::<Vec<SmolStr>>();
-        let has_more_derives = new_attr_input.len() > 0;
+        let has_more_derives = !new_attr_input.is_empty();
         let new_attr_input =
             join(new_attr_input.iter()).separator(", ").surround_with("(", ")").to_string();
         let new_attr_input_len = new_attr_input.len();
diff --git a/crates/ra_assists/src/handlers/add_new.rs b/crates/ra_assists/src/handlers/add_new.rs
index 2701eddb8..dd070e8ec 100644
--- a/crates/ra_assists/src/handlers/add_new.rs
+++ b/crates/ra_assists/src/handlers/add_new.rs
@@ -53,7 +53,7 @@ pub(crate) fn add_new(ctx: AssistCtx) -> Option<Assist> {
         }
 
         let vis = strukt.visibility().map(|v| format!("{} ", v.syntax()));
-        let vis = vis.as_ref().map(String::as_str).unwrap_or("");
+        let vis = vis.as_deref().unwrap_or("");
         write!(&mut buf, "    {}fn new(", vis).unwrap();
 
         join(field_list.fields().filter_map(|f| {
diff --git a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
index e6cd50bc1..0a0a88f3d 100644
--- a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
@@ -61,7 +61,7 @@ pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
 
         edit.target(if_expr.syntax().text_range());
         edit.set_cursor(if_expr.syntax().text_range().start());
-        edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr.into());
+        edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr);
     })
 }
 
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index cb124eaf0..a0e7fe17e 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -38,8 +38,8 @@ pub struct GroupLabel(pub String);
 impl AssistLabel {
     pub(crate) fn new(label: String, id: AssistId) -> AssistLabel {
         // FIXME: make fields private, so that this invariant can't be broken
-        assert!(label.chars().nth(0).unwrap().is_uppercase());
-        AssistLabel { label: label.into(), id }
+        assert!(label.chars().next().unwrap().is_uppercase());
+        AssistLabel { label, id }
     }
 }
 
diff --git a/crates/ra_cargo_watch/src/conv.rs b/crates/ra_cargo_watch/src/conv.rs
index 506370535..0246adfb5 100644
--- a/crates/ra_cargo_watch/src/conv.rs
+++ b/crates/ra_cargo_watch/src/conv.rs
@@ -234,7 +234,7 @@ pub(crate) fn map_rust_diagnostic_to_lsp(
         let child = map_rust_child_diagnostic(&child, workspace_root);
         match child {
             MappedRustChildDiagnostic::Related(related) => related_information.push(related),
-            MappedRustChildDiagnostic::SuggestedFix(code_action) => fixes.push(code_action.into()),
+            MappedRustChildDiagnostic::SuggestedFix(code_action) => fixes.push(code_action),
             MappedRustChildDiagnostic::MessageLine(message_line) => {
                 write!(&mut message, "\n{}", message_line).unwrap();
 
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index 1b4b47215..78d121683 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -249,7 +249,7 @@ impl FromStr for Edition {
         let res = match s {
             "2015" => Edition::Edition2015,
             "2018" => Edition::Edition2018,
-            _ => Err(ParseEditionError { invalid_input: s.to_string() })?,
+            _ => return Err(ParseEditionError { invalid_input: s.to_string() }),
         };
         Ok(res)
     }
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index b6adb7589..fe9149c9d 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -283,7 +283,7 @@ impl StructField {
         };
         let substs = Substs::type_params(db, generic_def_id);
         let ty = db.field_types(var_id)[self.id].clone().subst(&substs);
-        Type::new(db, self.parent.module(db).id.krate.into(), var_id, ty)
+        Type::new(db, self.parent.module(db).id.krate, var_id, ty)
     }
 
     pub fn parent_def(&self, _db: &impl HirDatabase) -> VariantDef {
@@ -315,11 +315,11 @@ impl Struct {
     }
 
     pub fn name(self, db: &impl DefDatabase) -> Name {
-        db.struct_data(self.id.into()).name.clone()
+        db.struct_data(self.id).name.clone()
     }
 
     pub fn fields(self, db: &impl HirDatabase) -> Vec<StructField> {
-        db.struct_data(self.id.into())
+        db.struct_data(self.id)
             .variant_data
             .fields()
             .iter()
@@ -332,7 +332,7 @@ impl Struct {
     }
 
     fn variant_data(self, db: &impl DefDatabase) -> Arc<VariantData> {
-        db.struct_data(self.id.into()).variant_data.clone()
+        db.struct_data(self.id).variant_data.clone()
     }
 }
 
@@ -1049,7 +1049,7 @@ impl Type {
         // FIXME check that?
         let canonical = Canonical { value: self.ty.value.clone(), num_vars: 0 };
         let environment = self.ty.environment.clone();
-        let ty = InEnvironment { value: canonical, environment: environment.clone() };
+        let ty = InEnvironment { value: canonical, environment };
         autoderef(db, Some(self.krate), ty)
             .map(|canonical| canonical.value)
             .map(move |ty| self.derived(ty))
diff --git a/crates/ra_hir/src/source_analyzer.rs b/crates/ra_hir/src/source_analyzer.rs
index 94d5b4cfd..efa3f8a79 100644
--- a/crates/ra_hir/src/source_analyzer.rs
+++ b/crates/ra_hir/src/source_analyzer.rs
@@ -361,9 +361,8 @@ impl SourceAnalyzer {
         db: &impl HirDatabase,
         macro_call: InFile<&ast::MacroCall>,
     ) -> Option<Expansion> {
-        let macro_call_id = macro_call.as_call_id(db, |path| {
-            self.resolver.resolve_path_as_macro(db, &path).map(|it| it.into())
-        })?;
+        let macro_call_id =
+            macro_call.as_call_id(db, |path| self.resolver.resolve_path_as_macro(db, &path))?;
         Some(Expansion { macro_call_id })
     }
 }
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 1fc892362..b1626fa11 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -448,7 +448,7 @@ where
             // FIXME expand to statements in statement position
             ast::Expr::MacroCall(e) => {
                 let macro_call = self.expander.to_source(AstPtr::new(&e));
-                match self.expander.enter_expand(self.db, e.clone()) {
+                match self.expander.enter_expand(self.db, e) {
                     Some((mark, expansion)) => {
                         self.source_map
                             .expansions
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index f765e6edc..e07a4f947 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -71,7 +71,7 @@ impl GenericParams {
         db: &impl DefDatabase,
         def: GenericDefId,
     ) -> Arc<GenericParams> {
-        let (params, _source_map) = GenericParams::new(db, def.into());
+        let (params, _source_map) = GenericParams::new(db, def);
         Arc::new(params)
     }
 
diff --git a/crates/ra_hir_def/src/item_scope.rs b/crates/ra_hir_def/src/item_scope.rs
index d74a1cef2..f8dc06d10 100644
--- a/crates/ra_hir_def/src/item_scope.rs
+++ b/crates/ra_hir_def/src/item_scope.rs
@@ -138,7 +138,7 @@ impl ItemScope {
 
     pub(crate) fn push_res(&mut self, name: Name, def: PerNs) -> bool {
         let mut changed = false;
-        let existing = self.visible.entry(name.clone()).or_default();
+        let existing = self.visible.entry(name).or_default();
 
         if existing.types.is_none() && def.types.is_some() {
             existing.types = def.types;
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 852304dd0..c5137a0ab 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -156,7 +156,7 @@ impl ModuleOrigin {
             ModuleOrigin::File { definition, .. } | ModuleOrigin::CrateRoot { definition } => {
                 let file_id = *definition;
                 let sf = db.parse(file_id).tree();
-                return InFile::new(file_id.into(), ModuleSource::SourceFile(sf));
+                InFile::new(file_id.into(), ModuleSource::SourceFile(sf))
             }
             ModuleOrigin::Inline { definition } => {
                 InFile::new(definition.file_id, ModuleSource::Module(definition.to_node(db)))
diff --git a/crates/ra_hir_def/src/nameres/raw.rs b/crates/ra_hir_def/src/nameres/raw.rs
index 650cf1f98..0e8c9da76 100644
--- a/crates/ra_hir_def/src/nameres/raw.rs
+++ b/crates/ra_hir_def/src/nameres/raw.rs
@@ -357,9 +357,7 @@ impl RawItemsCollector {
             let visibility =
                 RawVisibility::from_ast_with_hygiene(extern_crate.visibility(), &self.hygiene);
             let alias = extern_crate.alias().map(|a| {
-                a.name()
-                    .map(|it| it.as_name())
-                    .map_or(ImportAlias::Underscore, |a| ImportAlias::Alias(a))
+                a.name().map(|it| it.as_name()).map_or(ImportAlias::Underscore, ImportAlias::Alias)
             });
             let attrs = self.parse_attrs(&extern_crate);
             // FIXME: cfg_attr
diff --git a/crates/ra_hir_def/src/nameres/tests/incremental.rs b/crates/ra_hir_def/src/nameres/tests/incremental.rs
index faeb7aa4d..83f429c29 100644
--- a/crates/ra_hir_def/src/nameres/tests/incremental.rs
+++ b/crates/ra_hir_def/src/nameres/tests/incremental.rs
@@ -116,7 +116,7 @@ fn typing_inside_a_macro_should_not_invalidate_def_map() {
         let events = db.log_executed(|| {
             let crate_def_map = db.crate_def_map(krate);
             let (_, module_data) = crate_def_map.modules.iter().last().unwrap();
-            assert_eq!(module_data.scope.resolutions().collect::<Vec<_>>().len(), 1);
+            assert_eq!(module_data.scope.resolutions().count(), 1);
         });
         assert!(format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
     }
@@ -126,7 +126,7 @@ fn typing_inside_a_macro_should_not_invalidate_def_map() {
         let events = db.log_executed(|| {
             let crate_def_map = db.crate_def_map(krate);
             let (_, module_data) = crate_def_map.modules.iter().last().unwrap();
-            assert_eq!(module_data.scope.resolutions().collect::<Vec<_>>().len(), 1);
+            assert_eq!(module_data.scope.resolutions().count(), 1);
         });
         assert!(!format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
     }
diff --git a/crates/ra_hir_def/src/path/lower/lower_use.rs b/crates/ra_hir_def/src/path/lower/lower_use.rs
index d2bc9d193..b6d1125e2 100644
--- a/crates/ra_hir_def/src/path/lower/lower_use.rs
+++ b/crates/ra_hir_def/src/path/lower/lower_use.rs
@@ -32,9 +32,7 @@ pub(crate) fn lower_use_tree(
         }
     } else {
         let alias = tree.alias().map(|a| {
-            a.name()
-                .map(|it| it.as_name())
-                .map_or(ImportAlias::Underscore, |a| ImportAlias::Alias(a))
+            a.name().map(|it| it.as_name()).map_or(ImportAlias::Underscore, ImportAlias::Alias)
         });
         let is_glob = tree.has_star();
         if let Some(ast_path) = tree.path() {
diff --git a/crates/ra_hir_def/src/resolver.rs b/crates/ra_hir_def/src/resolver.rs
index e2b228e80..5365b80e2 100644
--- a/crates/ra_hir_def/src/resolver.rs
+++ b/crates/ra_hir_def/src/resolver.rs
@@ -474,7 +474,7 @@ impl Scope {
                     f(name.clone(), ScopeDef::PerNs(PerNs::macros(macro_, Visibility::Public)));
                 });
                 m.crate_def_map.extern_prelude.iter().for_each(|(name, &def)| {
-                    f(name.clone(), ScopeDef::PerNs(PerNs::types(def.into(), Visibility::Public)));
+                    f(name.clone(), ScopeDef::PerNs(PerNs::types(def, Visibility::Public)));
                 });
                 if let Some(prelude) = m.crate_def_map.prelude {
                     let prelude_def_map = db.crate_def_map(prelude.krate);
@@ -499,10 +499,10 @@ impl Scope {
                 }
             }
             Scope::ImplBlockScope(i) => {
-                f(name![Self], ScopeDef::ImplSelfType((*i).into()));
+                f(name![Self], ScopeDef::ImplSelfType(*i));
             }
             Scope::AdtScope(i) => {
-                f(name![Self], ScopeDef::AdtSelfType((*i).into()));
+                f(name![Self], ScopeDef::AdtSelfType(*i));
             }
             Scope::ExprScope(scope) => {
                 scope.expr_scopes.entries(scope.scope_id).iter().for_each(|e| {
diff --git a/crates/ra_hir_expand/src/builtin_derive.rs b/crates/ra_hir_expand/src/builtin_derive.rs
index 62c60e336..d0e3eaf7e 100644
--- a/crates/ra_hir_expand/src/builtin_derive.rs
+++ b/crates/ra_hir_expand/src/builtin_derive.rs
@@ -235,7 +235,7 @@ mod tests {
         let (db, file_id) = TestDB::with_single_file(&s);
         let parsed = db.parse(file_id);
         let items: Vec<_> =
-            parsed.syntax_node().descendants().filter_map(|it| ast::ModuleItem::cast(it)).collect();
+            parsed.syntax_node().descendants().filter_map(ast::ModuleItem::cast).collect();
 
         let ast_id_map = db.ast_id_map(file_id.into());
 
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index f3f959ac6..4adaa9b07 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -158,7 +158,7 @@ fn compile_error_expand(
         match &tt.token_trees[0] {
             tt::TokenTree::Leaf(tt::Leaf::Literal(it)) => {
                 let s = it.text.as_str();
-                if s.contains(r#"""#) {
+                if s.contains('"') {
                     return Ok(quote! { loop { #it }});
                 }
             }
@@ -222,7 +222,7 @@ mod tests {
         let (db, file_id) = TestDB::with_single_file(&s);
         let parsed = db.parse(file_id);
         let macro_calls: Vec<_> =
-            parsed.syntax_node().descendants().filter_map(|it| ast::MacroCall::cast(it)).collect();
+            parsed.syntax_node().descendants().filter_map(ast::MacroCall::cast).collect();
 
         let ast_id_map = db.ast_id_map(file_id.into());
 
diff --git a/crates/ra_hir_expand/src/quote.rs b/crates/ra_hir_expand/src/quote.rs
index 4de219ce4..b54e00b68 100644
--- a/crates/ra_hir_expand/src/quote.rs
+++ b/crates/ra_hir_expand/src/quote.rs
@@ -259,8 +259,7 @@ mod tests {
         // }
         let struct_name = mk_ident("Foo");
         let fields = [mk_ident("name"), mk_ident("id")];
-        let fields =
-            fields.iter().map(|it| quote!(#it: self.#it.clone(), ).token_trees.clone()).flatten();
+        let fields = fields.iter().map(|it| quote!(#it: self.#it.clone(), ).token_trees).flatten();
 
         let list = tt::Subtree {
             delimiter: Some(tt::Delimiter {
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index a9d958c8b..76069eb9c 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -225,14 +225,14 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             coerce_unsized_map: Self::init_coerce_unsized_map(db, &resolver),
             db,
             owner,
-            body: db.body(owner.into()),
+            body: db.body(owner),
             resolver,
         }
     }
 
     fn resolve_all(mut self) -> InferenceResult {
         // FIXME resolve obligations as well (use Guidance if necessary)
-        let mut result = mem::replace(&mut self.result, InferenceResult::default());
+        let mut result = std::mem::take(&mut self.result);
         for ty in result.type_of_expr.values_mut() {
             let resolved = self.table.resolve_ty_completely(mem::replace(ty, Ty::Unknown));
             *ty = resolved;
@@ -261,7 +261,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn write_assoc_resolution(&mut self, id: ExprOrPatId, item: AssocItemId) {
-        self.result.assoc_resolutions.insert(id, item.into());
+        self.result.assoc_resolutions.insert(id, item);
     }
 
     fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
@@ -312,9 +312,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         for obligation in obligations {
             let in_env = InEnvironment::new(self.trait_env.clone(), obligation.clone());
             let canonicalized = self.canonicalizer().canonicalize_obligation(in_env);
-            let solution = self
-                .db
-                .trait_solve(self.resolver.krate().unwrap().into(), canonicalized.value.clone());
+            let solution =
+                self.db.trait_solve(self.resolver.krate().unwrap(), canonicalized.value.clone());
 
             match solution {
                 Some(Solution::Unique(substs)) => {
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
index f68a1439f..4a0eabdfc 100644
--- a/crates/ra_hir_ty/src/infer/coerce.rs
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -44,10 +44,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         resolver: &Resolver,
     ) -> FxHashMap<(TypeCtor, TypeCtor), usize> {
         let krate = resolver.krate().unwrap();
-        let impls = match db.lang_item(krate.into(), "coerce_unsized".into()) {
-            Some(LangItemTarget::TraitId(trait_)) => {
-                db.impls_for_trait(krate.into(), trait_.into())
-            }
+        let impls = match db.lang_item(krate, "coerce_unsized".into()) {
+            Some(LangItemTarget::TraitId(trait_)) => db.impls_for_trait(krate, trait_),
             _ => return FxHashMap::default(),
         };
 
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 39d8bc0ca..0af94ae32 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -127,10 +127,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
                     Substs(sig_tys.into()),
                 );
-                let closure_ty = Ty::apply_one(
-                    TypeCtor::Closure { def: self.owner.into(), expr: tgt_expr },
-                    sig_ty,
-                );
+                let closure_ty =
+                    Ty::apply_one(TypeCtor::Closure { def: self.owner, expr: tgt_expr }, sig_ty);
 
                 // Eagerly try to relate the closure type with the expected
                 // type, otherwise we often won't have enough information to
@@ -165,7 +163,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::Match { expr, arms } => {
                 let input_ty = self.infer_expr(*expr, &Expectation::none());
 
-                let mut result_ty = if arms.len() == 0 {
+                let mut result_ty = if arms.is_empty() {
                     Ty::simple(TypeCtor::Never)
                 } else {
                     self.table.new_type_var()
@@ -188,7 +186,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             }
             Expr::Path(p) => {
                 // FIXME this could be more efficient...
-                let resolver = resolver_for_expr(self.db, self.owner.into(), tgt_expr);
+                let resolver = resolver_for_expr(self.db, self.owner, tgt_expr);
                 self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
             }
             Expr::Continue => Ty::simple(TypeCtor::Never),
@@ -217,8 +215,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 self.unify(&ty, &expected.ty);
 
                 let substs = ty.substs().unwrap_or_else(Substs::empty);
-                let field_types =
-                    def_id.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+                let field_types = def_id.map(|it| self.db.field_types(it)).unwrap_or_default();
                 let variant_data = def_id.map(|it| variant_data(self.db, it));
                 for (field_idx, field) in fields.iter().enumerate() {
                     let field_def =
@@ -264,7 +261,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
                         TypeCtor::Adt(AdtId::StructId(s)) => {
                             self.db.struct_data(s).variant_data.field(name).map(|local_id| {
-                                let field = StructFieldId { parent: s.into(), local_id }.into();
+                                let field = StructFieldId { parent: s.into(), local_id };
                                 self.write_field_resolution(tgt_expr, field);
                                 self.db.field_types(s.into())[field.local_id]
                                     .clone()
@@ -700,10 +697,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             // construct a TraitDef
                             let substs =
                                 a_ty.parameters.prefix(generics(self.db, trait_.into()).len());
-                            self.obligations.push(Obligation::Trait(TraitRef {
-                                trait_: trait_.into(),
-                                substs,
-                            }));
+                            self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
                         }
                     }
                     CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {}
diff --git a/crates/ra_hir_ty/src/infer/pat.rs b/crates/ra_hir_ty/src/infer/pat.rs
index a5dfdf6c4..a495ecbfe 100644
--- a/crates/ra_hir_ty/src/infer/pat.rs
+++ b/crates/ra_hir_ty/src/infer/pat.rs
@@ -28,7 +28,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let substs = ty.substs().unwrap_or_else(Substs::empty);
 
-        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+        let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
 
         for (i, &subpat) in subpats.iter().enumerate() {
             let expected_ty = var_data
@@ -60,7 +60,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let substs = ty.substs().unwrap_or_else(Substs::empty);
 
-        let field_tys = def.map(|it| self.db.field_types(it.into())).unwrap_or_default();
+        let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
         for subpat in subpats {
             let matching_field = var_data.as_ref().and_then(|it| it.field(&subpat.name));
             let expected_ty =
diff --git a/crates/ra_hir_ty/src/infer/path.rs b/crates/ra_hir_ty/src/infer/path.rs
index 686ce7a21..471d60342 100644
--- a/crates/ra_hir_ty/src/infer/path.rs
+++ b/crates/ra_hir_ty/src/infer/path.rs
@@ -104,8 +104,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let segment =
                     remaining_segments.last().expect("there should be at least one segment here");
                 let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver);
-                let trait_ref =
-                    TraitRef::from_resolved_path(&ctx, trait_.into(), resolved_segment, None);
+                let trait_ref = TraitRef::from_resolved_path(&ctx, trait_, resolved_segment, None);
                 self.resolve_trait_assoc_item(trait_ref, segment, id)
             }
             (def, _) => {
@@ -144,30 +143,32 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         id: ExprOrPatId,
     ) -> Option<(ValueNs, Option<Substs>)> {
         let trait_ = trait_ref.trait_;
-        let item = self
-            .db
-            .trait_data(trait_)
-            .items
-            .iter()
-            .map(|(_name, id)| (*id).into())
-            .find_map(|item| match item {
-                AssocItemId::FunctionId(func) => {
-                    if segment.name == &self.db.function_data(func).name {
-                        Some(AssocItemId::FunctionId(func))
-                    } else {
-                        None
+        let item =
+            self.db.trait_data(trait_).items.iter().map(|(_name, id)| (*id)).find_map(|item| {
+                match item {
+                    AssocItemId::FunctionId(func) => {
+                        if segment.name == &self.db.function_data(func).name {
+                            Some(AssocItemId::FunctionId(func))
+                        } else {
+                            None
+                        }
                     }
-                }
 
-                AssocItemId::ConstId(konst) => {
-                    if self.db.const_data(konst).name.as_ref().map_or(false, |n| n == segment.name)
-                    {
-                        Some(AssocItemId::ConstId(konst))
-                    } else {
-                        None
+                    AssocItemId::ConstId(konst) => {
+                        if self
+                            .db
+                            .const_data(konst)
+                            .name
+                            .as_ref()
+                            .map_or(false, |n| n == segment.name)
+                        {
+                            Some(AssocItemId::ConstId(konst))
+                        } else {
+                            None
+                        }
                     }
+                    AssocItemId::TypeAliasId(_) => None,
                 }
-                AssocItemId::TypeAliasId(_) => None,
             })?;
         let def = match item {
             AssocItemId::FunctionId(f) => ValueNs::FunctionId(f),
@@ -233,7 +234,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     AssocContainerId::ContainerId(_) => None,
                 };
 
-                self.write_assoc_resolution(id, item.into());
+                self.write_assoc_resolution(id, item);
                 Some((def, substs))
             },
         )
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 571579cc4..302bb8aa2 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -167,7 +167,7 @@ impl TypeCtor {
             | TypeCtor::Closure { .. } // 1 param representing the signature of the closure
             => 1,
             TypeCtor::Adt(adt) => {
-                let generic_params = generics(db, AdtId::from(adt).into());
+                let generic_params = generics(db, adt.into());
                 generic_params.len()
             }
             TypeCtor::FnDef(callable) => {
@@ -247,7 +247,7 @@ pub struct ProjectionTy {
 
 impl ProjectionTy {
     pub fn trait_ref(&self, db: &impl HirDatabase) -> TraitRef {
-        TraitRef { trait_: self.trait_(db).into(), substs: self.parameters.clone() }
+        TraitRef { trait_: self.trait_(db), substs: self.parameters.clone() }
     }
 
     fn trait_(&self, db: &impl HirDatabase) -> TraitId {
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index c2a3703fa..52da34574 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -361,10 +361,8 @@ impl Ty {
         for t in traits {
             if let Some(associated_ty) = ctx.db.trait_data(t).associated_type_by_name(&segment.name)
             {
-                let substs = Substs::build_for_def(ctx.db, t)
-                    .push(self_ty.clone())
-                    .fill_with_unknown()
-                    .build();
+                let substs =
+                    Substs::build_for_def(ctx.db, t).push(self_ty).fill_with_unknown().build();
                 // FIXME handle type parameters on the segment
                 return Ty::Projection(ProjectionTy { associated_ty, parameters: substs });
             }
@@ -428,7 +426,7 @@ pub(super) fn substs_from_path_segment(
     _add_self_param: bool,
 ) -> Substs {
     let mut substs = Vec::new();
-    let def_generics = def_generic.map(|def| generics(ctx.db, def.into()));
+    let def_generics = def_generic.map(|def| generics(ctx.db, def));
 
     let (parent_params, self_params, type_params, impl_trait_params) =
         def_generics.map_or((0, 0, 0, 0), |g| g.provenance_split());
@@ -459,7 +457,7 @@ pub(super) fn substs_from_path_segment(
 
     // handle defaults
     if let Some(def_generic) = def_generic {
-        let default_substs = ctx.db.generic_defaults(def_generic.into());
+        let default_substs = ctx.db.generic_defaults(def_generic);
         assert_eq!(substs.len(), default_substs.len());
 
         for (i, default_ty) in default_substs.iter().enumerate() {
@@ -483,7 +481,7 @@ impl TraitRef {
             _ => return None,
         };
         let segment = path.segments().last().expect("path should have at least one segment");
-        Some(TraitRef::from_resolved_path(ctx, resolved.into(), segment, explicit_self_ty))
+        Some(TraitRef::from_resolved_path(ctx, resolved, segment, explicit_self_ty))
     }
 
     pub(crate) fn from_resolved_path(
@@ -728,7 +726,7 @@ pub(crate) fn generic_predicates_query(
 pub(crate) fn generic_defaults_query(db: &impl HirDatabase, def: GenericDefId) -> Substs {
     let resolver = def.resolver(db);
     let ctx = TyLoweringContext::new(db, &resolver);
-    let generic_params = generics(db, def.into());
+    let generic_params = generics(db, def);
 
     let defaults = generic_params
         .iter()
@@ -792,7 +790,7 @@ fn type_for_builtin(def: BuiltinType) -> Ty {
 }
 
 fn fn_sig_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> PolyFnSig {
-    let struct_data = db.struct_data(def.into());
+    let struct_data = db.struct_data(def);
     let fields = struct_data.variant_data.fields();
     let resolver = def.resolver(db);
     let ctx =
@@ -805,7 +803,7 @@ fn fn_sig_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> PolyFn
 
 /// Build the type of a tuple struct constructor.
 fn type_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> Binders<Ty> {
-    let struct_data = db.struct_data(def.into());
+    let struct_data = db.struct_data(def);
     if let StructKind::Unit = struct_data.variant_data.kind() {
         return type_for_adt(db, def.into());
     }
@@ -836,7 +834,7 @@ fn type_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariantId)
     }
     let generics = generics(db, def.parent.into());
     let substs = Substs::bound_vars(&generics);
-    Binders::new(substs.len(), Ty::apply(TypeCtor::FnDef(EnumVariantId::from(def).into()), substs))
+    Binders::new(substs.len(), Ty::apply(TypeCtor::FnDef(def.into()), substs))
 }
 
 fn type_for_adt(db: &impl HirDatabase, adt: AdtId) -> Binders<Ty> {
@@ -964,6 +962,6 @@ pub(crate) fn impl_trait_query(
     let target_trait = impl_data.target_trait.as_ref()?;
     Some(Binders::new(
         self_ty.num_binders,
-        TraitRef::from_hir(&ctx, target_trait, Some(self_ty.value.clone()))?,
+        TraitRef::from_hir(&ctx, target_trait, Some(self_ty.value))?,
     ))
 }
diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
index 4f8c52433..964acdb09 100644
--- a/crates/ra_hir_ty/src/method_resolution.rs
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -214,7 +214,7 @@ pub fn iterate_method_candidates<T>(
             // the methods by autoderef order of *receiver types*, not *self
             // types*.
 
-            let deref_chain: Vec<_> = autoderef::autoderef(db, Some(krate), ty.clone()).collect();
+            let deref_chain: Vec<_> = autoderef::autoderef(db, Some(krate), ty).collect();
             for i in 0..deref_chain.len() {
                 if let Some(result) = iterate_method_candidates_with_autoref(
                     &deref_chain[i..],
@@ -290,7 +290,7 @@ fn iterate_method_candidates_with_autoref<T>(
         &ref_muted,
         deref_chain,
         db,
-        env.clone(),
+        env,
         krate,
         &traits_in_scope,
         name,
@@ -391,17 +391,17 @@ fn iterate_trait_method_candidates<T>(
         // iteration
         let mut known_implemented = false;
         for (_name, item) in data.items.iter() {
-            if !is_valid_candidate(db, name, receiver_ty, (*item).into(), self_ty) {
+            if !is_valid_candidate(db, name, receiver_ty, *item, self_ty) {
                 continue;
             }
             if !known_implemented {
                 let goal = generic_implements_goal(db, env.clone(), t, self_ty.clone());
-                if db.trait_solve(krate.into(), goal).is_none() {
+                if db.trait_solve(krate, goal).is_none() {
                     continue 'traits;
                 }
             }
             known_implemented = true;
-            if let Some(result) = callback(&self_ty.value, (*item).into()) {
+            if let Some(result) = callback(&self_ty.value, *item) {
                 return Some(result);
             }
         }
@@ -521,7 +521,7 @@ pub fn implements_trait(
         return true;
     }
     let goal = generic_implements_goal(db, env, trait_, ty.clone());
-    let solution = db.trait_solve(krate.into(), goal);
+    let solution = db.trait_solve(krate, goal);
 
     solution.is_some()
 }
diff --git a/crates/ra_hir_ty/src/traits/builtin.rs b/crates/ra_hir_ty/src/traits/builtin.rs
index dd41176f0..67120abf6 100644
--- a/crates/ra_hir_ty/src/traits/builtin.rs
+++ b/crates/ra_hir_ty/src/traits/builtin.rs
@@ -98,7 +98,7 @@ fn closure_fn_trait_impl_datum(
         // the existence of the Fn trait has been checked before
         .expect("fn trait for closure impl missing");
 
-    let num_args: u16 = match &db.body(data.def.into())[data.expr] {
+    let num_args: u16 = match &db.body(data.def)[data.expr] {
         Expr::Lambda { args, .. } => args.len() as u16,
         _ => {
             log::warn!("closure for closure type {:?} not found", data);
@@ -118,7 +118,7 @@ fn closure_fn_trait_impl_datum(
     let self_ty = Ty::apply_one(TypeCtor::Closure { def: data.def, expr: data.expr }, sig_ty);
 
     let trait_ref = TraitRef {
-        trait_: trait_.into(),
+        trait_,
         substs: Substs::build_for_def(db, trait_).push(self_ty).push(arg_ty).build(),
     };
 
@@ -139,7 +139,7 @@ fn closure_fn_trait_output_assoc_ty_value(
 ) -> BuiltinImplAssocTyValueData {
     let impl_ = Impl::ClosureFnTraitImpl(data.clone());
 
-    let num_args: u16 = match &db.body(data.def.into())[data.expr] {
+    let num_args: u16 = match &db.body(data.def)[data.expr] {
         Expr::Lambda { args, .. } => args.len() as u16,
         _ => {
             log::warn!("closure for closure type {:?} not found", data);
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index 882160fa8..306909ec2 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -565,10 +565,10 @@ where
         // and will panic if the trait can't be resolved.
         let mut result: Vec<_> = self
             .db
-            .impls_for_trait(self.krate, trait_.into())
+            .impls_for_trait(self.krate, trait_)
             .iter()
             .copied()
-            .map(|it| Impl::ImplBlock(it.into()))
+            .map(Impl::ImplBlock)
             .map(|impl_| impl_.to_chalk(self.db))
             .collect();
 
@@ -586,7 +586,7 @@ where
         false // FIXME
     }
     fn associated_ty_value(&self, id: AssociatedTyValueId) -> Arc<AssociatedTyValue> {
-        self.db.associated_ty_value(self.krate.into(), id)
+        self.db.associated_ty_value(self.krate, id)
     }
     fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<TypeFamily>> {
         vec![]
@@ -674,7 +674,7 @@ pub(crate) fn struct_datum_query(
     let where_clauses = type_ctor
         .as_generic_def()
         .map(|generic_def| {
-            let generic_params = generics(db, generic_def.into());
+            let generic_params = generics(db, generic_def);
             let bound_vars = Substs::bound_vars(&generic_params);
             convert_where_clauses(db, generic_def, &bound_vars)
         })
@@ -805,7 +805,7 @@ fn type_alias_associated_ty_value(
     let ty = db.ty(type_alias.into());
     let value_bound = chalk_rust_ir::AssociatedTyValueBound { ty: ty.value.to_chalk(db) };
     let value = chalk_rust_ir::AssociatedTyValue {
-        impl_id: Impl::ImplBlock(impl_id.into()).to_chalk(db),
+        impl_id: Impl::ImplBlock(impl_id).to_chalk(db),
         associated_ty_id: assoc_ty.to_chalk(db),
         value: make_binders(value_bound, ty.num_binders),
     };
diff --git a/crates/ra_ide_db/src/change.rs b/crates/ra_ide_db/src/change.rs
index 4668784d3..7e9310005 100644
--- a/crates/ra_ide_db/src/change.rs
+++ b/crates/ra_ide_db/src/change.rs
@@ -44,7 +44,7 @@ impl fmt::Debug for AnalysisChange {
         if !self.libraries_added.is_empty() {
             d.field("libraries_added", &self.libraries_added.len());
         }
-        if !self.crate_graph.is_none() {
+        if self.crate_graph.is_some() {
             d.field("crate_graph", &self.crate_graph);
         }
         d.finish()
diff --git a/crates/ra_mbe/src/mbe_expander/matcher.rs b/crates/ra_mbe/src/mbe_expander/matcher.rs
index e36b5a412..2bdea11e1 100644
--- a/crates/ra_mbe/src/mbe_expander/matcher.rs
+++ b/crates/ra_mbe/src/mbe_expander/matcher.rs
@@ -101,7 +101,7 @@ fn match_subtree(
                         tt::Leaf::Literal(tt::Literal { text: lhs, .. }),
                         tt::Leaf::Literal(tt::Literal { text: rhs, .. }),
                     ) if lhs == rhs => (),
-                    _ => Err(ExpandError::UnexpectedToken)?,
+                    _ => return Err(ExpandError::UnexpectedToken),
                 }
             }
             Op::TokenTree(tt::TokenTree::Subtree(lhs)) => {
diff --git a/crates/ra_mbe/src/parser.rs b/crates/ra_mbe/src/parser.rs
index 50b8011a9..1cdebc216 100644
--- a/crates/ra_mbe/src/parser.rs
+++ b/crates/ra_mbe/src/parser.rs
@@ -100,7 +100,7 @@ fn next_op<'a>(
                     Op::Repeat { subtree, separator, kind }
                 }
                 tt::TokenTree::Leaf(leaf) => match leaf {
-                    tt::Leaf::Punct(..) => Err(ExpandError::UnexpectedToken)?,
+                    tt::Leaf::Punct(..) => return Err(ExpandError::UnexpectedToken),
                     tt::Leaf::Ident(ident) => {
                         let name = &ident.text;
                         let kind = eat_fragment_kind(src, mode)?;
@@ -147,15 +147,15 @@ fn parse_repeat(src: &mut TtIter) -> Result<(Option<Separator>, RepeatKind), Exp
     for tt in src {
         let tt = match tt {
             tt::TokenTree::Leaf(leaf) => leaf,
-            tt::TokenTree::Subtree(_) => Err(ExpandError::InvalidRepeat)?,
+            tt::TokenTree::Subtree(_) => return Err(ExpandError::InvalidRepeat),
         };
         let has_sep = match &separator {
-            Separator::Puncts(puncts) => puncts.len() != 0,
+            Separator::Puncts(puncts) => !puncts.is_empty(),
             _ => true,
         };
         match tt {
             tt::Leaf::Ident(_) | tt::Leaf::Literal(_) if has_sep => {
-                Err(ExpandError::InvalidRepeat)?
+                return Err(ExpandError::InvalidRepeat)
             }
             tt::Leaf::Ident(ident) => separator = Separator::Ident(ident.clone()),
             tt::Leaf::Literal(lit) => separator = Separator::Literal(lit.clone()),
@@ -168,11 +168,11 @@ fn parse_repeat(src: &mut TtIter) -> Result<(Option<Separator>, RepeatKind), Exp
                         match &mut separator {
                             Separator::Puncts(puncts) => {
                                 if puncts.len() == 3 {
-                                    Err(ExpandError::InvalidRepeat)?
+                                    return Err(ExpandError::InvalidRepeat);
                                 }
                                 puncts.push(punct.clone())
                             }
-                            _ => Err(ExpandError::InvalidRepeat)?,
+                            _ => return Err(ExpandError::InvalidRepeat),
                         }
                         continue;
                     }
diff --git a/crates/ra_mbe/src/subtree_source.rs b/crates/ra_mbe/src/subtree_source.rs
index c9f42b3dd..eb8b79e9a 100644
--- a/crates/ra_mbe/src/subtree_source.rs
+++ b/crates/ra_mbe/src/subtree_source.rs
@@ -124,7 +124,7 @@ fn convert_delim(d: Option<tt::DelimiterKind>, closing: bool) -> TtToken {
 
     let idx = closing as usize;
     let kind = kinds[idx];
-    let text = if texts.len() > 0 { &texts[idx..texts.len() - (1 - idx)] } else { "" };
+    let text = if !texts.is_empty() { &texts[idx..texts.len() - (1 - idx)] } else { "" };
     TtToken { kind, is_joint_to_next: false, text: SmolStr::new(text) }
 }
 
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index b72d2e9e6..b77b683b5 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -230,10 +230,8 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
     p.eat(T![async]);
     p.eat(T![move]);
     params::param_list_closure(p);
-    if opt_fn_ret_type(p) {
-        if !p.at(T!['{']) {
-            p.error("expected `{`");
-        }
+    if opt_fn_ret_type(p) && !p.at(T!['{']) {
+        p.error("expected `{`");
     }
 
     if p.at_ts(EXPR_FIRST) {
diff --git a/crates/ra_parser/src/grammar/paths.rs b/crates/ra_parser/src/grammar/paths.rs
index f5bf3d7ce..332acc1a0 100644
--- a/crates/ra_parser/src/grammar/paths.rs
+++ b/crates/ra_parser/src/grammar/paths.rs
@@ -94,7 +94,7 @@ fn path_segment(p: &mut Parser, mode: Mode, first: bool) {
 
 fn opt_path_type_args(p: &mut Parser, mode: Mode) {
     match mode {
-        Mode::Use => return,
+        Mode::Use => {}
         Mode::Type => {
             // test path_fn_trait_args
             // type F = Box<Fn(i32) -> ()>;
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index c267bc85f..660d85b42 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -214,7 +214,7 @@ impl Drop for Profiler {
                     let start = stack.starts.pop().unwrap();
                     let duration = start.elapsed();
                     let level = stack.starts.len();
-                    stack.messages.push(Message { level, duration, label: label });
+                    stack.messages.push(Message { level, duration, label });
                     if level == 0 {
                         let stdout = stderr();
                         let longer_than = stack.filter_data.longer_than;
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 22d226a74..34fd73bb7 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -164,7 +164,7 @@ impl CargoWorkspace {
             // FIXME: `NoDefaultFeatures` is mutual exclusive with `SomeFeatures`
             // https://github.com/oli-obk/cargo_metadata/issues/79
             meta.features(CargoOpt::NoDefaultFeatures);
-        } else if cargo_features.features.len() > 0 {
+        } else if !cargo_features.features.is_empty() {
             meta.features(CargoOpt::SomeFeatures(cargo_features.features.clone()));
         }
         if let Some(parent) = cargo_toml.parent() {
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 250255813..9e67d2498 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -409,7 +409,7 @@ fn find_cargo_toml(path: &Path) -> Result<PathBuf> {
         }
         curr = path.parent();
     }
-    Err(CargoTomlNotFoundError(path.to_path_buf()))?
+    Err(CargoTomlNotFoundError(path.to_path_buf()).into())
 }
 
 pub fn get_rustc_cfg_options() -> CfgOptions {
diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
index acf677e7d..21fca99a6 100644
--- a/crates/ra_syntax/src/algo.rs
+++ b/crates/ra_syntax/src/algo.rs
@@ -95,16 +95,17 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
         lhs: SyntaxElement,
         rhs: SyntaxElement,
     ) {
-        if lhs.kind() == rhs.kind() && lhs.text_range().len() == rhs.text_range().len() {
-            if match (&lhs, &rhs) {
+        if lhs.kind() == rhs.kind()
+            && lhs.text_range().len() == rhs.text_range().len()
+            && match (&lhs, &rhs) {
                 (NodeOrToken::Node(lhs), NodeOrToken::Node(rhs)) => {
                     lhs.green() == rhs.green() || lhs.text() == rhs.text()
                 }
                 (NodeOrToken::Token(lhs), NodeOrToken::Token(rhs)) => lhs.text() == rhs.text(),
                 _ => false,
-            } {
-                return;
             }
+        {
+            return;
         }
         if let (Some(lhs), Some(rhs)) = (lhs.as_node(), rhs.as_node()) {
             if lhs.children_with_tokens().count() == rhs.children_with_tokens().count() {
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 2e50a095c..77cceb382 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -30,7 +30,7 @@ pub enum ElseBranch {
 
 impl ast::IfExpr {
     pub fn then_branch(&self) -> Option<ast::BlockExpr> {
-        self.blocks().nth(0)
+        self.blocks().next()
     }
     pub fn else_branch(&self) -> Option<ElseBranch> {
         let res = match self.blocks().nth(1) {
@@ -208,7 +208,7 @@ impl ast::BinExpr {
     }
 
     pub fn lhs(&self) -> Option<ast::Expr> {
-        children(self).nth(0)
+        children(self).next()
     }
 
     pub fn rhs(&self) -> Option<ast::Expr> {
@@ -271,7 +271,7 @@ impl ast::RangeExpr {
 
 impl ast::IndexExpr {
     pub fn base(&self) -> Option<ast::Expr> {
-        children(self).nth(0)
+        children(self).next()
     }
     pub fn index(&self) -> Option<ast::Expr> {
         children(self).nth(1)
@@ -287,7 +287,7 @@ impl ast::ArrayExpr {
     pub fn kind(&self) -> ArrayExprKind {
         if self.is_repeat() {
             ArrayExprKind::Repeat {
-                initializer: children(self).nth(0),
+                initializer: children(self).next(),
                 repeat: children(self).nth(1),
             }
         } else {
@@ -328,10 +328,10 @@ impl ast::Literal {
     }
 
     pub fn kind(&self) -> LiteralKind {
-        const INT_SUFFIXES: [&'static str; 12] = [
+        const INT_SUFFIXES: [&str; 12] = [
             "u64", "u32", "u16", "u8", "usize", "isize", "i64", "i32", "i16", "i8", "u128", "i128",
         ];
-        const FLOAT_SUFFIXES: [&'static str; 2] = ["f32", "f64"];
+        const FLOAT_SUFFIXES: [&str; 2] = ["f32", "f64"];
 
         let token = self.token();
 
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 89d1403e7..7c20fcc10 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -152,7 +152,7 @@ pub fn match_arm_list(arms: impl IntoIterator<Item = ast::MatchArm>) -> ast::Mat
             format!("    {}{}\n", arm.syntax(), comma)
         })
         .collect::<String>();
-    return from_text(&format!("{}", arms_str));
+    return from_text(&arms_str);
 
     fn from_text(text: &str) -> ast::MatchArmList {
         ast_from_text(&format!("fn f() {{ match () {{\n{}}} }}", text))
diff --git a/crates/ra_syntax/src/parsing/text_token_source.rs b/crates/ra_syntax/src/parsing/text_token_source.rs
index e793f93a4..e2433913c 100644
--- a/crates/ra_syntax/src/parsing/text_token_source.rs
+++ b/crates/ra_syntax/src/parsing/text_token_source.rs
@@ -48,7 +48,7 @@ impl<'t> TokenSource for TextTokenSource<'t> {
 
     fn is_keyword(&self, kw: &str) -> bool {
         let pos = self.curr.1;
-        if !(pos < self.tokens.len()) {
+        if pos >= self.tokens.len() {
             return false;
         }
         let range = TextRange::offset_len(self.start_offsets[pos], self.tokens[pos].len);
diff --git a/crates/rust-analyzer/src/bin/main.rs b/crates/rust-analyzer/src/bin/main.rs
index 69e709a25..dd15b3458 100644
--- a/crates/rust-analyzer/src/bin/main.rs
+++ b/crates/rust-analyzer/src/bin/main.rs
@@ -4,7 +4,7 @@
 mod args;
 
 use lsp_server::Connection;
-use ra_prof;
+
 use rust_analyzer::{cli, from_json, show_message, Result, ServerConfig};
 
 use crate::args::HelpPrinted;
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index 99ab6e443..4d59db1ee 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -130,7 +130,7 @@ pub fn analysis_stats(
             write!(msg, " ({:?} {})", path, syntax_range).unwrap();
         }
         if verbosity.is_spammy() {
-            bar.println(format!("{}", msg));
+            bar.println(msg.to_string());
         }
         bar.set_message(&msg);
         let f_id = FunctionId::from(f);
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index dc16a234d..71917a62e 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -206,17 +206,17 @@ pub fn main_loop(
             let event = select! {
                 recv(&connection.receiver) -> msg => match msg {
                     Ok(msg) => Event::Msg(msg),
-                    Err(RecvError) => Err("client exited without shutdown")?,
+                    Err(RecvError) => return Err("client exited without shutdown".into()),
                 },
                 recv(task_receiver) -> task => Event::Task(task.unwrap()),
                 recv(world_state.task_receiver) -> task => match task {
                     Ok(task) => Event::Vfs(task),
-                    Err(RecvError) => Err("vfs died")?,
+                    Err(RecvError) => return Err("vfs died".into()),
                 },
                 recv(libdata_receiver) -> data => Event::Lib(data.unwrap()),
                 recv(world_state.check_watcher.task_recv) -> task => match task {
                     Ok(task) => Event::CheckWatcher(task),
-                    Err(RecvError) => Err("check watcher died")?,
+                    Err(RecvError) => return Err("check watcher died".into()),
                 }
             };
             if let Event::Msg(Message::Request(req)) = &event {
diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/heavy_tests/main.rs
index 3af63d9cf..970185dec 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/main.rs
@@ -17,7 +17,7 @@ use test_utils::skip_slow_tests;
 
 use crate::support::{project, Project};
 
-const PROFILE: &'static str = "";
+const PROFILE: &str = "";
 // const PROFILE: &'static str = "*@3>100";
 
 #[test]
diff --git a/crates/rust-analyzer/tests/heavy_tests/support.rs b/crates/rust-analyzer/tests/heavy_tests/support.rs
index 5b90b3218..e28ae61fe 100644
--- a/crates/rust-analyzer/tests/heavy_tests/support.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/support.rs
@@ -52,7 +52,7 @@ impl<'a> Project<'a> {
         let tmp_dir = self.tmp_dir.unwrap_or_else(|| TempDir::new().unwrap());
         static INIT: Once = Once::new();
         INIT.call_once(|| {
-            let _ = env_logger::builder().is_test(true).try_init().unwrap();
+            env_logger::builder().is_test(true).try_init().unwrap();
             ra_prof::set_filter(if crate::PROFILE.is_empty() {
                 ra_prof::Filter::disabled()
             } else {
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index 336c594a6..e6e8d7110 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -279,7 +279,7 @@ pub fn find_mismatch<'a>(expected: &'a Value, actual: &'a Value) -> Option<(&'a
                 return Some((expected, actual));
             }
 
-            l.values().zip(r.values()).filter_map(|(l, r)| find_mismatch(l, r)).nth(0)
+            l.values().zip(r.values()).filter_map(|(l, r)| find_mismatch(l, r)).next()
         }
         (&Null, &Null) => None,
         // magic string literal "{...}" acts as wildcard for any sub-JSON