64 files changed, 382 insertions, 237 deletions

diff --git a/crates/ra_assists/src/ast_editor.rs b/crates/ra_assists/src/ast_editor.rs
index cabb3d862..de0529b32 100644
--- a/crates/ra_assists/src/ast_editor.rs
+++ b/crates/ra_assists/src/ast_editor.rs
@@ -212,21 +212,17 @@ impl AstEditor<ast::FnDef> {
     }
 
     pub fn strip_attrs_and_docs(&mut self) {
-        loop {
-            if let Some(start) = self
-                .ast()
-                .syntax()
-                .children_with_tokens()
-                .find(|it| it.kind() == ATTR || it.kind() == COMMENT)
-            {
-                let end = match start.next_sibling_or_token() {
-                    Some(el) if el.kind() == WHITESPACE => el,
-                    Some(_) | None => start,
-                };
-                self.ast = self.replace_children(RangeInclusive::new(start, end), iter::empty());
-            } else {
-                break;
-            }
+        while let Some(start) = self
+            .ast()
+            .syntax()
+            .children_with_tokens()
+            .find(|it| it.kind() == ATTR || it.kind() == COMMENT)
+        {
+            let end = match start.next_sibling_or_token() {
+                Some(el) if el.kind() == WHITESPACE => el,
+                Some(_) | None => start,
+            };
+            self.ast = self.replace_children(RangeInclusive::new(start, end), iter::empty());
         }
     }
 }
diff --git a/crates/ra_assists/src/auto_import.rs b/crates/ra_assists/src/auto_import.rs
index 1566cf179..9617beb5c 100644
--- a/crates/ra_assists/src/auto_import.rs
+++ b/crates/ra_assists/src/auto_import.rs
@@ -334,7 +334,7 @@ fn best_action_for_target<'b, 'a: 'b>(
         .filter_map(ast::UseItem::use_tree)
         .map(|u| walk_use_tree_for_best_action(&mut storage, None, u, target))
         .fold(None, |best, a| {
-            best.and_then(|best| Some(*ImportAction::better(&best, &a))).or(Some(a))
+            best.and_then(|best| Some(*ImportAction::better(&best, &a))).or_else(|| Some(a))
         });
 
     match best_action {
@@ -347,7 +347,7 @@ fn best_action_for_target<'b, 'a: 'b>(
             let anchor = container
                 .children()
                 .find(|n| n.range().start() < anchor.range().start())
-                .or(Some(anchor));
+                .or_else(|| Some(anchor));
 
             return ImportAction::add_new_use(anchor, false);
         }
diff --git a/crates/ra_assists/src/change_visibility.rs b/crates/ra_assists/src/change_visibility.rs
index 620f534b5..4eb24d27f 100644
--- a/crates/ra_assists/src/change_visibility.rs
+++ b/crates/ra_assists/src/change_visibility.rs
@@ -59,7 +59,7 @@ fn vis_offset(node: &SyntaxNode) -> TextUnit {
         })
         .next()
         .map(|it| it.range().start())
-        .unwrap_or(node.range().start())
+        .unwrap_or_else(|| node.range().start())
 }
 
 fn change_vis(mut ctx: AssistCtx<impl HirDatabase>, vis: &ast::Visibility) -> Option<Assist> {
diff --git a/crates/ra_assists/src/introduce_variable.rs b/crates/ra_assists/src/introduce_variable.rs
index fb7333c8c..28467d341 100644
--- a/crates/ra_assists/src/introduce_variable.rs
+++ b/crates/ra_assists/src/introduce_variable.rs
@@ -57,9 +57,9 @@ pub(crate) fn introduce_variable(mut ctx: AssistCtx<impl HirDatabase>) -> Option
             if text.starts_with("\r\n") {
                 buf.push_str("\r\n");
                 buf.push_str(text.trim_start_matches("\r\n"));
-            } else if text.starts_with("\n") {
+            } else if text.starts_with('\n') {
                 buf.push_str("\n");
-                buf.push_str(text.trim_start_matches("\n"));
+                buf.push_str(text.trim_start_matches('\n'));
             } else {
                 buf.push_str(text);
             }
diff --git a/crates/ra_batch/src/lib.rs b/crates/ra_batch/src/lib.rs
index a4a8462de..a445dcb4d 100644
--- a/crates/ra_batch/src/lib.rs
+++ b/crates/ra_batch/src/lib.rs
@@ -34,10 +34,10 @@ impl salsa::Database for BatchDatabase {
 }
 
 fn vfs_file_to_id(f: ra_vfs::VfsFile) -> FileId {
-    FileId(f.0.into())
+    FileId(f.0)
 }
 fn vfs_root_to_id(r: ra_vfs::VfsRoot) -> SourceRootId {
-    SourceRootId(r.0.into())
+    SourceRootId(r.0)
 }
 
 impl BatchDatabase {
diff --git a/crates/ra_cli/src/analysis_stats.rs b/crates/ra_cli/src/analysis_stats.rs
index b481ace9e..8bb524ce3 100644
--- a/crates/ra_cli/src/analysis_stats.rs
+++ b/crates/ra_cli/src/analysis_stats.rs
@@ -31,18 +31,16 @@ pub fn run(verbose: bool, path: &str, only: Option<&str>) -> Result<()> {
 
             for decl in module.declarations(&db) {
                 num_decls += 1;
-                match decl {
-                    ModuleDef::Function(f) => funcs.push(f),
-                    _ => {}
+                if let ModuleDef::Function(f) = decl {
+                    funcs.push(f);
                 }
             }
 
             for impl_block in module.impl_blocks(&db) {
                 for item in impl_block.items(&db) {
                     num_decls += 1;
-                    match item {
-                        ImplItem::Method(f) => funcs.push(f),
-                        _ => {}
+                    if let ImplItem::Method(f) = item {
+                        funcs.push(f);
                     }
                 }
             }
diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index 45a12dd4d..38ff1d6f6 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -36,7 +36,7 @@ impl AdtDef {
 
 impl Struct {
     pub(crate) fn variant_data(&self, db: &impl DefDatabase) -> Arc<VariantData> {
-        db.struct_data((*self).into()).variant_data.clone()
+        db.struct_data(*self).variant_data.clone()
     }
 }
 
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 9c02b3995..6ee6bd627 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -281,9 +281,8 @@ impl Module {
 
         for impl_block in self.impl_blocks(db) {
             for item in impl_block.items(db) {
-                match item {
-                    crate::ImplItem::Method(f) => f.diagnostics(db, sink),
-                    _ => (),
+                if let crate::ImplItem::Method(f) = item {
+                    f.diagnostics(db, sink);
                 }
             }
         }
diff --git a/crates/ra_hir/src/diagnostics.rs b/crates/ra_hir/src/diagnostics.rs
index 4b7b2dbee..2557ef18e 100644
--- a/crates/ra_hir/src/diagnostics.rs
+++ b/crates/ra_hir/src/diagnostics.rs
@@ -87,7 +87,7 @@ impl Diagnostic for NoSuchField {
     fn syntax_node_ptr(&self) -> SyntaxNodePtr {
         self.field.into()
     }
-    fn as_any(&self) -> &(Any + Send + 'static) {
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
         self
     }
 }
@@ -109,7 +109,7 @@ impl Diagnostic for UnresolvedModule {
     fn syntax_node_ptr(&self) -> SyntaxNodePtr {
         self.decl.into()
     }
-    fn as_any(&self) -> &(Any + Send + 'static) {
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
         self
     }
 }
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 51913d37b..9d9769859 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -6,7 +6,7 @@ use rustc_hash::FxHashMap;
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use ra_syntax::{
     SyntaxNodePtr, AstPtr, AstNode,
-    ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind,ArrayExprKind, TypeAscriptionOwner},
+    ast::{self, TryBlockBodyOwner, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind,ArrayExprKind, TypeAscriptionOwner},
 };
 
 use crate::{
@@ -216,6 +216,9 @@ pub enum Expr {
     Try {
         expr: ExprId,
     },
+    TryBlock {
+        body: ExprId,
+    },
     Cast {
         expr: ExprId,
         type_ref: TypeRef,
@@ -299,6 +302,7 @@ impl Expr {
                     f(*expr);
                 }
             }
+            Expr::TryBlock { body } => f(*body),
             Expr::Loop { body } => f(*body),
             Expr::While { condition, body } => {
                 f(*condition);
@@ -578,6 +582,10 @@ where
                     self.alloc_expr(Expr::If { condition, then_branch, else_branch }, syntax_ptr)
                 }
             }
+            ast::ExprKind::TryBlockExpr(e) => {
+                let body = self.collect_block_opt(e.try_body());
+                self.alloc_expr(Expr::TryBlock { body }, syntax_ptr)
+            }
             ast::ExprKind::BlockExpr(e) => self.collect_block_opt(e.block()),
             ast::ExprKind::LoopExpr(e) => {
                 let body = self.collect_block_opt(e.loop_body());
diff --git a/crates/ra_hir/src/expr/validation.rs b/crates/ra_hir/src/expr/validation.rs
index 2816144a7..a1b2641da 100644
--- a/crates/ra_hir/src/expr/validation.rs
+++ b/crates/ra_hir/src/expr/validation.rs
@@ -31,11 +31,8 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
     pub(crate) fn validate_body(&mut self, db: &impl HirDatabase) {
         let body = self.func.body(db);
         for e in body.exprs() {
-            match e {
-                (id, Expr::StructLit { path, fields, spread }) => {
-                    self.validate_struct_literal(id, path, fields, spread, db)
-                }
-                _ => (),
+            if let (id, Expr::StructLit { path, fields, spread }) = e {
+                self.validate_struct_literal(id, path, fields, spread, db);
             }
         }
     }
@@ -44,7 +41,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         &mut self,
         id: ExprId,
         _path: &Option<Path>,
-        fields: &Vec<StructLitField>,
+        fields: &[StructLitField],
         spread: &Option<ExprId>,
         db: &impl HirDatabase,
     ) {
@@ -57,7 +54,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             _ => return,
         };
 
-        let lit_fields: FxHashSet<_> = fields.into_iter().map(|f| &f.name).collect();
+        let lit_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
         let missed_fields: Vec<Name> = struct_def
             .fields(db)
             .iter()
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index ba90e67e9..a0d3b33fe 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -202,7 +202,6 @@ impl ModuleImplBlocks {
         };
 
         let (file_id, module_source) = m.module.definition_source(db);
-        let file_id: HirFileId = file_id.into();
         let node = match &module_source {
             ModuleSource::SourceFile(node) => node.syntax(),
             ModuleSource::Module(node) => {
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
index 4cacaeba4..684fbc068 100644
--- a/crates/ra_hir/src/lang_item.rs
+++ b/crates/ra_hir/src/lang_item.rs
@@ -95,7 +95,7 @@ impl LangItems {
                 .nth(0);
             if let Some(lang_item_name) = lang_item_name {
                 let imp = ImplBlock::from_id(*module, impl_id);
-                self.items.entry(lang_item_name).or_insert(LangItemTarget::ImplBlock(imp));
+                self.items.entry(lang_item_name).or_insert_with(|| LangItemTarget::ImplBlock(imp));
             }
         }
 
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index d649aa820..8b798d6c9 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -332,7 +332,8 @@ impl CrateDefMap {
         let name = path.expand_macro_expr()?;
         // search local first
         // FIXME: Remove public_macros check when we have a correct local_macors implementation
-        let local = self.public_macros.get(&name).or(self.local_macros.get(&name)).map(|it| *it);
+        let local =
+            self.public_macros.get(&name).or_else(|| self.local_macros.get(&name)).map(|it| *it);
         if local.is_some() {
             return local;
         }
@@ -405,7 +406,7 @@ impl CrateDefMap {
         };
 
         for (i, segment) in segments {
-            let curr = match curr_per_ns.as_ref().left().map_or(None, |m| m.as_ref().take_types()) {
+            let curr = match curr_per_ns.as_ref().left().and_then(|m| m.as_ref().take_types()) {
                 Some(r) => r,
                 None => {
                     // we still have path segments left, but the path so far
@@ -421,10 +422,8 @@ impl CrateDefMap {
             curr_per_ns = match curr {
                 ModuleDef::Module(module) => {
                     if module.krate != self.krate {
-                        let path = Path {
-                            segments: path.segments[i..].iter().cloned().collect(),
-                            kind: PathKind::Self_,
-                        };
+                        let path =
+                            Path { segments: path.segments[i..].to_vec(), kind: PathKind::Self_ };
                         log::debug!("resolving {:?} in other crate", path);
                         let defp_map = db.crate_def_map(module.krate);
                         let (def, s) =
@@ -468,7 +467,7 @@ impl CrateDefMap {
                     );
 
                     return ResolvePathResult::with(
-                        Either::Left(PerNs::types((*s).into())),
+                        Either::Left(PerNs::types(*s)),
                         ReachedFixedPoint::Yes,
                         Some(i),
                     );
@@ -479,8 +478,10 @@ impl CrateDefMap {
     }
 
     fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> ItemOrMacro {
-        let from_crate_root =
-            self[self.root].scope.get_item_or_macro(name).unwrap_or(Either::Left(PerNs::none()));
+        let from_crate_root = self[self.root]
+            .scope
+            .get_item_or_macro(name)
+            .unwrap_or_else(|| Either::Left(PerNs::none()));
         let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
 
         or(from_crate_root, Either::Left(from_extern_prelude))
@@ -505,8 +506,10 @@ impl CrateDefMap {
         //  - current module / scope
         //  - extern prelude
         //  - std prelude
-        let from_scope =
-            self[module].scope.get_item_or_macro(name).unwrap_or(Either::Left(PerNs::none()));;
+        let from_scope = self[module]
+            .scope
+            .get_item_or_macro(name)
+            .unwrap_or_else(|| Either::Left(PerNs::none()));;
         let from_extern_prelude =
             self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it));
         let from_prelude = self.resolve_in_prelude(db, name);
@@ -525,7 +528,7 @@ impl CrateDefMap {
             } else {
                 db.crate_def_map(prelude.krate)[prelude.module_id].scope.get_item_or_macro(name)
             };
-            resolution.unwrap_or(Either::Left(PerNs::none()))
+            resolution.unwrap_or_else(|| Either::Left(PerNs::none()))
         } else {
             Either::Left(PerNs::none())
         }
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index 693c3fe8e..3bfef799d 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -556,7 +556,7 @@ where
 
     fn define_def(&mut self, def: &raw::DefData) {
         let module = Module { krate: self.def_collector.def_map.krate, module_id: self.module_id };
-        let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id.into());
+        let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id);
 
         macro_rules! def {
             ($kind:ident, $ast_id:ident) => {
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index 21935dbb9..a0afe282c 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir/src/nameres/raw.rs
@@ -69,7 +69,7 @@ impl RawItems {
     ) -> (Arc<RawItems>, Arc<ImportSourceMap>) {
         let mut collector = RawItemsCollector {
             raw_items: RawItems::default(),
-            source_ast_id_map: db.ast_id_map(file_id.into()),
+            source_ast_id_map: db.ast_id_map(file_id),
             source_map: ImportSourceMap::default(),
         };
         if let Some(node) = db.parse_or_expand(file_id) {
diff --git a/crates/ra_hir/src/path.rs b/crates/ra_hir/src/path.rs
index 1b129c752..67afd5027 100644
--- a/crates/ra_hir/src/path.rs
+++ b/crates/ra_hir/src/path.rs
@@ -116,7 +116,7 @@ impl Path {
 
     /// `true` if this path is just a standalone `self`
     pub fn is_self(&self) -> bool {
-        self.kind == PathKind::Self_ && self.segments.len() == 0
+        self.kind == PathKind::Self_ && self.segments.is_empty()
     }
 
     /// If this path is a single identifier, like `foo`, return its name.
@@ -140,7 +140,7 @@ impl GenericArgs {
             args.push(GenericArg::Type(type_ref));
         }
         // lifetimes and assoc type args ignored for now
-        if args.len() > 0 {
+        if !args.is_empty() {
             Some(GenericArgs { args })
         } else {
             None
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 75ed2de6c..6a5799622 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -48,8 +48,8 @@ pub fn module_from_declaration(
 pub fn module_from_position(db: &impl HirDatabase, position: FilePosition) -> Option<Module> {
     let file = db.parse(position.file_id).tree;
     match find_node_at_offset::<ast::Module>(file.syntax(), position.offset) {
-        Some(m) if !m.has_semi() => module_from_inline(db, position.file_id.into(), m),
-        _ => module_from_file_id(db, position.file_id.into()),
+        Some(m) if !m.has_semi() => module_from_inline(db, position.file_id, m),
+        _ => module_from_file_id(db, position.file_id),
     }
 }
 
@@ -72,9 +72,9 @@ pub fn module_from_child_node(
     child: &SyntaxNode,
 ) -> Option<Module> {
     if let Some(m) = child.ancestors().filter_map(ast::Module::cast).find(|it| !it.has_semi()) {
-        module_from_inline(db, file_id.into(), m)
+        module_from_inline(db, file_id, m)
     } else {
-        module_from_file_id(db, file_id.into())
+        module_from_file_id(db, file_id)
     }
 }
 
@@ -99,14 +99,12 @@ pub fn struct_from_module(
     struct_def: &ast::StructDef,
 ) -> Struct {
     let (file_id, _) = module.definition_source(db);
-    let file_id = file_id.into();
     let ctx = LocationCtx::new(db, module, file_id);
     Struct { id: ctx.to_def(struct_def) }
 }
 
 pub fn enum_from_module(db: &impl HirDatabase, module: Module, enum_def: &ast::EnumDef) -> Enum {
     let (file_id, _) = module.definition_source(db);
-    let file_id = file_id.into();
     let ctx = LocationCtx::new(db, module, file_id);
     Enum { id: ctx.to_def(enum_def) }
 }
@@ -117,7 +115,6 @@ pub fn trait_from_module(
     trait_def: &ast::TraitDef,
 ) -> Trait {
     let (file_id, _) = module.definition_source(db);
-    let file_id = file_id.into();
     let ctx = LocationCtx::new(db, module, file_id);
     Trait { id: ctx.to_def(trait_def) }
 }
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
index 2a7c2b791..967654e97 100644
--- a/crates/ra_hir/src/traits.rs
+++ b/crates/ra_hir/src/traits.rs
@@ -77,13 +77,10 @@ impl TraitItemsIndex {
     pub(crate) fn trait_items_index(db: &impl DefDatabase, module: Module) -> TraitItemsIndex {
         let mut index = TraitItemsIndex { traits_by_def: FxHashMap::default() };
         for decl in module.declarations(db) {
-            match decl {
-                crate::ModuleDef::Trait(tr) => {
-                    for item in tr.trait_data(db).items() {
-                        index.traits_by_def.insert(*item, tr);
-                    }
+            if let crate::ModuleDef::Trait(tr) = decl {
+                for item in tr.trait_data(db).items() {
+                    index.traits_by_def.insert(*item, tr);
                 }
-                _ => {}
             }
         }
         index
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 76d34c12b..4a37e0268 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -451,7 +451,7 @@ impl Ty {
     /// Substitutes `Ty::Bound` vars (as opposed to type parameters).
     pub fn subst_bound_vars(self, substs: &Substs) -> Ty {
         self.fold(&mut |ty| match ty {
-            Ty::Bound(idx) => substs.get(idx as usize).cloned().unwrap_or(Ty::Bound(idx)),
+            Ty::Bound(idx) => substs.get(idx as usize).cloned().unwrap_or_else(|| Ty::Bound(idx)),
             ty => ty,
         })
     }
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index e8ae33ead..6cc5dbc6f 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -462,7 +462,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let mut resolved =
             if remaining_index.is_none() { def.take_values()? } else { def.take_types()? };
 
-        let remaining_index = remaining_index.unwrap_or(path.segments.len());
+        let remaining_index = remaining_index.unwrap_or_else(|| path.segments.len());
         let mut actual_def_ty: Option<Ty> = None;
 
         let krate = resolver.krate()?;
@@ -539,7 +539,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
             })?;
 
-            resolved = Resolution::Def(item.into());
+            resolved = Resolution::Def(item);
         }
 
         match resolved {
@@ -762,7 +762,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     _ => &Ty::Unknown,
                 };
                 let subty = self.infer_pat(*pat, expectation, default_bm);
-                Ty::apply_one(TypeCtor::Ref(*mutability), subty.into())
+                Ty::apply_one(TypeCtor::Ref(*mutability), subty)
             }
             Pat::TupleStruct { path: ref p, args: ref subpats } => {
                 self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
@@ -790,7 +790,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 let bound_ty = match mode {
                     BindingMode::Ref(mutability) => {
-                        Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone().into())
+                        Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone())
                     }
                     BindingMode::Move => inner_ty.clone(),
                 };
@@ -848,28 +848,23 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
-        match callable_ty {
-            Ty::Apply(a_ty) => match a_ty.ctor {
-                TypeCtor::FnDef(def) => {
-                    // add obligation for trait implementation, if this is a trait method
-                    // FIXME also register obligations from where clauses from the trait or impl and method
-                    match def {
-                        CallableDef::Function(f) => {
-                            if let Some(trait_) = f.parent_trait(self.db) {
-                                // construct a TraitDef
-                                let substs = a_ty.parameters.prefix(
-                                    trait_.generic_params(self.db).count_params_including_parent(),
-                                );
-                                self.obligations
-                                    .push(Obligation::Trait(TraitRef { trait_, substs }));
-                            }
+        if let Ty::Apply(a_ty) = callable_ty {
+            if let TypeCtor::FnDef(def) = a_ty.ctor {
+                // add obligation for trait implementation, if this is a trait method
+                // FIXME also register obligations from where clauses from the trait or impl and method
+                match def {
+                    CallableDef::Function(f) => {
+                        if let Some(trait_) = f.parent_trait(self.db) {
+                            // construct a TraitDef
+                            let substs = a_ty.parameters.prefix(
+                                trait_.generic_params(self.db).count_params_including_parent(),
+                            );
+                            self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
                         }
-                        CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {}
                     }
+                    CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {}
                 }
-                _ => {}
-            },
-            _ => {}
+            }
         }
     }
 
@@ -951,6 +946,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 then_ty
             }
             Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
+            Expr::TryBlock { body } => {
+                let _inner = self.infer_expr(*body, expected);
+                // FIXME should be std::result::Result<{inner}, _>
+                Ty::Unknown
+            }
             Expr::Loop { body } => {
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
                 // FIXME handle break with value
@@ -1049,7 +1049,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::StructLit { path, fields, spread } => {
                 let (ty, def_id) = self.resolve_variant(path.as_ref());
                 let substs = ty.substs().unwrap_or_else(Substs::empty);
-                for (field_idx, field) in fields.into_iter().enumerate() {
+                for (field_idx, field) in fields.iter().enumerate() {
                     let field_ty = def_id
                         .and_then(|it| match it.field(self.db, &field.name) {
                             Some(field) => Some(field),
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 34817a5ec..646e58aa9 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -192,23 +192,20 @@ fn iterate_trait_method_candidates<T>(
         // iteration
         let mut known_implemented = false;
         for item in data.items() {
-            match item {
-                &TraitItem::Function(m) => {
-                    let sig = m.signature(db);
-                    if name.map_or(true, |name| sig.name() == name) && sig.has_self_param() {
-                        if !known_implemented {
-                            let trait_ref = canonical_trait_ref(db, t, ty.clone());
-                            if db.implements(krate, trait_ref).is_none() {
-                                continue 'traits;
-                            }
-                        }
-                        known_implemented = true;
-                        if let Some(result) = callback(&ty.value, m) {
-                            return Some(result);
+            if let TraitItem::Function(m) = *item {
+                let sig = m.signature(db);
+                if name.map_or(true, |name| sig.name() == name) && sig.has_self_param() {
+                    if !known_implemented {
+                        let trait_ref = canonical_trait_ref(db, t, ty.clone());
+                        if db.implements(krate, trait_ref).is_none() {
+                            continue 'traits;
                         }
                     }
+                    known_implemented = true;
+                    if let Some(result) = callback(&ty.value, m) {
+                        return Some(result);
+                    }
                 }
-                _ => {}
             }
         }
     }
@@ -230,16 +227,13 @@ fn iterate_inherent_methods<T>(
 
     for impl_block in impls.lookup_impl_blocks(&ty.value) {
         for item in impl_block.items(db) {
-            match item {
-                ImplItem::Method(f) => {
-                    let sig = f.signature(db);
-                    if name.map_or(true, |name| sig.name() == name) && sig.has_self_param() {
-                        if let Some(result) = callback(&ty.value, f) {
-                            return Some(result);
-                        }
+            if let ImplItem::Method(f) = item {
+                let sig = f.signature(db);
+                if name.map_or(true, |name| sig.name() == name) && sig.has_self_param() {
+                    if let Some(result) = callback(&ty.value, f) {
+                        return Some(result);
                     }
                 }
-                _ => {}
             }
         }
     }
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 78440b258..1e4806db0 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -211,13 +211,10 @@ fn convert_where_clauses(
             // anyway), otherwise Chalk can easily get into slow situations
             return vec![pred.clone().subst(substs).to_chalk(db)];
         }
-        match pred {
-            GenericPredicate::Implemented(trait_ref) => {
-                if blacklisted_trait(db, trait_ref.trait_) {
-                    continue;
-                }
+        if let GenericPredicate::Implemented(trait_ref) = pred {
+            if blacklisted_trait(db, trait_ref.trait_) {
+                continue;
             }
-            _ => {}
         }
         result.push(pred.clone().subst(substs).to_chalk(db));
     }
diff --git a/crates/ra_ide_api/src/call_info.rs b/crates/ra_ide_api/src/call_info.rs
index 5d43282fd..bd08e183d 100644
--- a/crates/ra_ide_api/src/call_info.rs
+++ b/crates/ra_ide_api/src/call_info.rs
@@ -21,8 +21,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
     let function = match calling_node {
         FnCallNode::CallExpr(expr) => {
             //FIXME: apply subst
-            let (callable_def, _subst) =
-                analyzer.type_of(db, expr.expr()?.into())?.as_callable()?;
+            let (callable_def, _subst) = analyzer.type_of(db, expr.expr()?)?.as_callable()?;
             match callable_def {
                 hir::CallableDef::Function(it) => it,
                 //FIXME: handle other callables
@@ -64,7 +63,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<Cal
 
             // If we are in a method account for `self`
             if has_self {
-                param = param + 1;
+                param += 1;
             }
 
             call_info.active_parameter = Some(param);
diff --git a/crates/ra_ide_api/src/completion/complete_dot.rs b/crates/ra_ide_api/src/completion/complete_dot.rs
index 5bf289c63..0822a0e7e 100644
--- a/crates/ra_ide_api/src/completion/complete_dot.rs
+++ b/crates/ra_ide_api/src/completion/complete_dot.rs
@@ -16,8 +16,8 @@ pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
 
 fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty) {
     for receiver in receiver.autoderef(ctx.db) {
-        match receiver {
-            Ty::Apply(a_ty) => match a_ty.ctor {
+        if let Ty::Apply(a_ty) = receiver {
+            match a_ty.ctor {
                 TypeCtor::Adt(AdtDef::Struct(s)) => {
                     for field in s.fields(ctx.db) {
                         acc.add_field(ctx, field, &a_ty.parameters);
@@ -30,8 +30,7 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: Ty)
                     }
                 }
                 _ => {}
-            },
-            _ => {}
+            }
         };
     }
 }
diff --git a/crates/ra_ide_api/src/completion/complete_pattern.rs b/crates/ra_ide_api/src/completion/complete_pattern.rs
index 74833a756..6655a05a7 100644
--- a/crates/ra_ide_api/src/completion/complete_pattern.rs
+++ b/crates/ra_ide_api/src/completion/complete_pattern.rs
@@ -10,7 +10,7 @@ pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
     let names = ctx.analyzer.all_names(ctx.db);
     for (name, res) in names.into_iter() {
         let r = res.as_ref();
-        let def = match r.take_types().or(r.take_values()) {
+        let def = match r.take_types().or_else(|| r.take_values()) {
             Some(hir::Resolution::Def(def)) => def,
             _ => continue,
         };
diff --git a/crates/ra_ide_api/src/completion/complete_scope.rs b/crates/ra_ide_api/src/completion/complete_scope.rs
index 2473e58b4..0f8cfaae8 100644
--- a/crates/ra_ide_api/src/completion/complete_scope.rs
+++ b/crates/ra_ide_api/src/completion/complete_scope.rs
@@ -49,7 +49,7 @@ pub(super) fn complete_scope(acc: &mut Completions, ctx: &CompletionContext) {
     }
 }
 
-fn build_import_label(name: &str, path: &Vec<SmolStr>) -> String {
+fn build_import_label(name: &str, path: &[SmolStr]) -> String {
     let mut buf = String::with_capacity(64);
     buf.push_str(name);
     buf.push_str(" (");
@@ -58,7 +58,7 @@ fn build_import_label(name: &str, path: &Vec<SmolStr>) -> String {
     buf
 }
 
-fn fmt_import_path(path: &Vec<SmolStr>, buf: &mut String) {
+fn fmt_import_path(path: &[SmolStr], buf: &mut String) {
     let mut segments = path.iter();
     if let Some(s) = segments.next() {
         buf.push_str(&s);
diff --git a/crates/ra_ide_api/src/diagnostics.rs b/crates/ra_ide_api/src/diagnostics.rs
index a2a8c1e4f..35b3d77df 100644
--- a/crates/ra_ide_api/src/diagnostics.rs
+++ b/crates/ra_ide_api/src/diagnostics.rs
@@ -109,7 +109,7 @@ fn check_unnecessary_braces_in_use_statement(
 
         acc.push(Diagnostic {
             range,
-            message: format!("Unnecessary braces in use statement"),
+            message: "Unnecessary braces in use statement".to_string(),
             severity: Severity::WeakWarning,
             fix: Some(SourceChange::source_file_edit(
                 "Remove unnecessary braces",
@@ -155,7 +155,7 @@ fn check_struct_shorthand_initialization(
 
                 acc.push(Diagnostic {
                     range: named_field.syntax().range(),
-                    message: format!("Shorthand struct initialization"),
+                    message: "Shorthand struct initialization".to_string(),
                     severity: Severity::WeakWarning,
                     fix: Some(SourceChange::source_file_edit(
                         "use struct shorthand initialization",
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index 00c445310..a713b762c 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -95,7 +95,7 @@ fn extend_single_word_in_comment_or_string(
     }
 
     let start_idx = before.rfind(non_word_char)? as u32;
-    let end_idx = after.find(non_word_char).unwrap_or(after.len()) as u32;
+    let end_idx = after.find(non_word_char).unwrap_or_else(|| after.len()) as u32;
 
     let from: TextUnit = (start_idx + 1).into();
     let to: TextUnit = (cursor_position + end_idx).into();
diff --git a/crates/ra_ide_api/src/folding_ranges.rs b/crates/ra_ide_api/src/folding_ranges.rs
index b50bbee38..4400ff232 100644
--- a/crates/ra_ide_api/src/folding_ranges.rs
+++ b/crates/ra_ide_api/src/folding_ranges.rs
@@ -205,7 +205,7 @@ mod tests {
             "The amount of fold kinds is different than the expected amount"
         );
         for ((fold, range), fold_kind) in
-            folds.into_iter().zip(ranges.into_iter()).zip(fold_kinds.into_iter())
+            folds.iter().zip(ranges.into_iter()).zip(fold_kinds.iter())
         {
             assert_eq!(fold.range.start(), range.start());
             assert_eq!(fold.range.end(), range.end());
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 9c35db2a4..f56965ef5 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -18,6 +18,12 @@ pub struct HoverResult {
     exact: bool,
 }
 
+impl Default for HoverResult {
+    fn default() -> Self {
+        HoverResult::new()
+    }
+}
+
 impl HoverResult {
     pub fn new() -> HoverResult {
         HoverResult {
diff --git a/crates/ra_ide_api/src/line_index.rs b/crates/ra_ide_api/src/line_index.rs
index fd33d6767..087dfafed 100644
--- a/crates/ra_ide_api/src/line_index.rs
+++ b/crates/ra_ide_api/src/line_index.rs
@@ -41,7 +41,7 @@ impl LineIndex {
                 newlines.push(curr_row);
 
                 // Save any utf-16 characters seen in the previous line
-                if utf16_chars.len() > 0 {
+                if !utf16_chars.is_empty() {
                     utf16_lines.insert(line, utf16_chars);
                     utf16_chars = Vec::new();
                 }
@@ -61,7 +61,7 @@ impl LineIndex {
         }
 
         // Save any utf-16 characters seen in the last line
-        if utf16_chars.len() > 0 {
+        if !utf16_chars.is_empty() {
             utf16_lines.insert(line, utf16_chars);
         }
 
diff --git a/crates/ra_ide_api/src/line_index_utils.rs b/crates/ra_ide_api/src/line_index_utils.rs
index 799a920ad..a03467011 100644
--- a/crates/ra_ide_api/src/line_index_utils.rs
+++ b/crates/ra_ide_api/src/line_index_utils.rs
@@ -133,9 +133,9 @@ impl<'a> Edits<'a> {
     }
 
     fn next_steps(&mut self, step: &Step) -> NextSteps {
-        let step_pos = match step {
-            &Step::Newline(n) => n,
-            &Step::Utf16Char(r) => r.end(),
+        let step_pos = match *step {
+            Step::Newline(n) => n,
+            Step::Utf16Char(r) => r.end(),
         };
         let res = match &mut self.current {
             Some(edit) => {
@@ -181,9 +181,9 @@ impl<'a> Edits<'a> {
         if self.acc_diff == 0 {
             x.clone()
         } else {
-            match x {
-                &Step::Newline(n) => Step::Newline(self.translate(n)),
-                &Step::Utf16Char(r) => Step::Utf16Char(self.translate_range(r)),
+            match *x {
+                Step::Newline(n) => Step::Newline(self.translate(n)),
+                Step::Utf16Char(r) => Step::Utf16Char(self.translate_range(r)),
             }
         }
     }
diff --git a/crates/ra_ide_api/src/typing.rs b/crates/ra_ide_api/src/typing.rs
index 63bc0cf88..3e35d8352 100644
--- a/crates/ra_ide_api/src/typing.rs
+++ b/crates/ra_ide_api/src/typing.rs
@@ -110,7 +110,7 @@ pub(crate) fn on_dot_typed(db: &RootDatabase, position: FilePosition) -> Option<
     let mut edit = TextEditBuilder::default();
     edit.replace(
         TextRange::from_to(position.offset - current_indent_len, position.offset),
-        target_indent.into(),
+        target_indent,
     );
 
     let res = SourceChange::source_file_edit_from("reindent dot", position.file_id, edit.finish())
diff --git a/crates/ra_lsp_server/src/cargo_target_spec.rs b/crates/ra_lsp_server/src/cargo_target_spec.rs
index 742361155..082ac8609 100644
--- a/crates/ra_lsp_server/src/cargo_target_spec.rs
+++ b/crates/ra_lsp_server/src/cargo_target_spec.rs
@@ -64,7 +64,7 @@ impl CargoTargetSpec {
             None => return Ok(None),
         };
         let file_id = world.analysis().crate_root(crate_id)?;
-        let path = world.vfs.read().file2path(ra_vfs::VfsFile(file_id.0.into()));
+        let path = world.vfs.read().file2path(ra_vfs::VfsFile(file_id.0));
         let res = world.workspaces.iter().find_map(|ws| match ws {
             project_model::ProjectWorkspace::Cargo { cargo, .. } => {
                 let tgt = cargo.target_by_root(&path)?;
diff --git a/crates/ra_lsp_server/src/main.rs b/crates/ra_lsp_server/src/main.rs
index b0b70df5c..a0df32dde 100644
--- a/crates/ra_lsp_server/src/main.rs
+++ b/crates/ra_lsp_server/src/main.rs
@@ -49,7 +49,7 @@ fn main_inner() -> Result<()> {
         let opts = params
             .initialization_options
             .and_then(|v| InitializationOptions::deserialize(v).ok())
-            .unwrap_or(InitializationOptions::default());
+            .unwrap_or_default();
 
         ra_lsp_server::main_loop(workspace_roots, opts, r, s)
     })?;
diff --git a/crates/ra_lsp_server/src/main_loop.rs b/crates/ra_lsp_server/src/main_loop.rs
index 6080a3a4e..090fb9b1b 100644
--- a/crates/ra_lsp_server/src/main_loop.rs
+++ b/crates/ra_lsp_server/src/main_loop.rs
@@ -384,7 +384,7 @@ fn on_notification(
             if let Some(file_id) =
                 state.vfs.write().add_file_overlay(&path, params.text_document.text)
             {
-                subs.add_sub(FileId(file_id.0.into()));
+                subs.add_sub(FileId(file_id.0));
             }
             return Ok(());
         }
@@ -406,7 +406,7 @@ fn on_notification(
             let uri = params.text_document.uri;
             let path = uri.to_file_path().map_err(|()| format_err!("invalid uri: {}", uri))?;
             if let Some(file_id) = state.vfs.write().remove_file_overlay(path.as_path()) {
-                subs.remove_sub(FileId(file_id.0.into()));
+                subs.remove_sub(FileId(file_id.0));
             }
             let params = req::PublishDiagnosticsParams { uri, diagnostics: Vec::new() };
             let not = RawNotification::new::<req::PublishDiagnostics>(&params);
diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index e0d2f6306..cd8df4fdb 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -60,14 +60,14 @@ impl WorldState {
         for r in vfs_roots {
             let vfs_root_path = vfs.root2path(r);
             let is_local = folder_roots.iter().any(|it| vfs_root_path.starts_with(it));
-            change.add_root(SourceRootId(r.0.into()), is_local);
+            change.add_root(SourceRootId(r.0), is_local);
         }
 
         // Create crate graph from all the workspaces
         let mut crate_graph = CrateGraph::default();
         let mut load = |path: &std::path::Path| {
             let vfs_file = vfs.load(path);
-            vfs_file.map(|f| FileId(f.0.into()))
+            vfs_file.map(|f| FileId(f.0))
         };
         for ws in workspaces.iter() {
             crate_graph.extend(ws.to_crate_graph(&mut load));
@@ -105,29 +105,24 @@ impl WorldState {
                     if is_local {
                         self.roots_to_scan -= 1;
                         for (file, path, text) in files {
-                            change.add_file(
-                                SourceRootId(root.0.into()),
-                                FileId(file.0.into()),
-                                path,
-                                text,
-                            );
+                            change.add_file(SourceRootId(root.0), FileId(file.0), path, text);
                         }
                     } else {
                         let files = files
                             .into_iter()
-                            .map(|(vfsfile, path, text)| (FileId(vfsfile.0.into()), path, text))
+                            .map(|(vfsfile, path, text)| (FileId(vfsfile.0), path, text))
                             .collect();
-                        libs.push((SourceRootId(root.0.into()), files));
+                        libs.push((SourceRootId(root.0), files));
                     }
                 }
                 VfsChange::AddFile { root, file, path, text } => {
-                    change.add_file(SourceRootId(root.0.into()), FileId(file.0.into()), path, text);
+                    change.add_file(SourceRootId(root.0), FileId(file.0), path, text);
                 }
                 VfsChange::RemoveFile { root, file, path } => {
-                    change.remove_file(SourceRootId(root.0.into()), FileId(file.0.into()), path)
+                    change.remove_file(SourceRootId(root.0), FileId(file.0), path)
                 }
                 VfsChange::ChangeFile { file, text } => {
-                    change.change_file(FileId(file.0.into()), text);
+                    change.change_file(FileId(file.0), text);
                 }
             }
         }
@@ -178,18 +173,18 @@ impl WorldSnapshot {
                 message: "Rust file outside current workspace is not supported yet.".to_string(),
             })
         })?;
-        Ok(FileId(file.0.into()))
+        Ok(FileId(file.0))
     }
 
     pub fn file_id_to_uri(&self, id: FileId) -> Result<Url> {
-        let path = self.vfs.read().file2path(VfsFile(id.0.into()));
+        let path = self.vfs.read().file2path(VfsFile(id.0));
         let url = Url::from_file_path(&path)
             .map_err(|_| format_err!("can't convert path to url: {}", path.display()))?;
         Ok(url)
     }
 
     pub fn path_to_uri(&self, root: SourceRootId, path: &RelativePathBuf) -> Result<Url> {
-        let base = self.vfs.read().root2path(VfsRoot(root.0.into()));
+        let base = self.vfs.read().root2path(VfsRoot(root.0));
         let path = path.to_path(base);
         let url = Url::from_file_path(&path)
             .map_err(|_| format_err!("can't convert path to url: {}", path.display()))?;
@@ -212,7 +207,7 @@ impl WorldSnapshot {
     }
 
     pub fn workspace_root_for(&self, file_id: FileId) -> Option<&Path> {
-        let path = self.vfs.read().file2path(VfsFile(file_id.0.into()));
+        let path = self.vfs.read().file2path(VfsFile(file_id.0));
         self.workspaces.iter().find_map(|ws| ws.workspace_root_for(&path))
     }
 }
diff --git a/crates/ra_lsp_server/tests/heavy_tests/support.rs b/crates/ra_lsp_server/tests/heavy_tests/support.rs
index f952a03a3..75912afdd 100644
--- a/crates/ra_lsp_server/tests/heavy_tests/support.rs
+++ b/crates/ra_lsp_server/tests/heavy_tests/support.rs
@@ -94,14 +94,9 @@ impl Server {
         let worker = Worker::<RawMessage, RawMessage>::spawn(
             "test server",
             128,
-            move |mut msg_receiver, mut msg_sender| {
-                main_loop(
-                    roots,
-                    InitializationOptions::default(),
-                    &mut msg_receiver,
-                    &mut msg_sender,
-                )
-                .unwrap()
+            move |msg_receiver, msg_sender| {
+                main_loop(roots, InitializationOptions::default(), &msg_receiver, &msg_sender)
+                    .unwrap()
             },
         );
         let res = Server { req_id: Cell::new(1), dir, messages: Default::default(), worker };
@@ -141,15 +136,14 @@ impl Server {
         R::Params: Serialize,
     {
         let actual = self.send_request::<R>(params);
-        match find_mismatch(&expected_resp, &actual) {
-            Some((expected_part, actual_part)) => panic!(
+        if let Some((expected_part, actual_part)) = find_mismatch(&expected_resp, &actual) {
+            panic!(
                 "JSON mismatch\nExpected:\n{}\nWas:\n{}\nExpected part:\n{}\nActual part:\n{}\n",
                 to_string_pretty(&expected_resp).unwrap(),
                 to_string_pretty(&actual).unwrap(),
                 to_string_pretty(expected_part).unwrap(),
                 to_string_pretty(actual_part).unwrap(),
-            ),
-            None => {}
+            );
         }
     }
 
diff --git a/crates/ra_mbe/src/mbe_expander.rs b/crates/ra_mbe/src/mbe_expander.rs
index a0bd0c5f8..55a6ecf58 100644
--- a/crates/ra_mbe/src/mbe_expander.rs
+++ b/crates/ra_mbe/src/mbe_expander.rs
@@ -105,17 +105,15 @@ impl Bindings {
     }
 
     fn get(&self, name: &SmolStr, nesting: &[usize]) -> Result<&tt::TokenTree, ExpandError> {
-        let mut b = self
-            .inner
-            .get(name)
-            .ok_or(ExpandError::BindingError(format!("could not find binding `{}`", name)))?;
+        let mut b = self.inner.get(name).ok_or_else(|| {
+            ExpandError::BindingError(format!("could not find binding `{}`", name))
+        })?;
         for &idx in nesting.iter() {
             b = match b {
                 Binding::Simple(_) => break,
-                Binding::Nested(bs) => bs.get(idx).ok_or(ExpandError::BindingError(format!(
-                    "could not find nested binding `{}`",
-                    name
-                )))?,
+                Binding::Nested(bs) => bs.get(idx).ok_or_else(|| {
+                    ExpandError::BindingError(format!("could not find nested binding `{}`", name))
+                })?,
                 Binding::Empty => {
                     return Err(ExpandError::BindingError(format!(
                         "could not find empty binding `{}`",
@@ -206,48 +204,48 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
                         "path" => {
                             let path =
                                 input.eat_path().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(path.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(path));
                         }
                         "expr" => {
                             let expr =
                                 input.eat_expr().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(expr.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(expr));
                         }
                         "ty" => {
                             let ty = input.eat_ty().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(ty.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(ty));
                         }
                         "pat" => {
                             let pat = input.eat_pat().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(pat.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(pat));
                         }
                         "stmt" => {
                             let pat = input.eat_stmt().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(pat.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(pat));
                         }
                         "block" => {
                             let block =
                                 input.eat_block().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(block.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(block));
                         }
                         "meta" => {
                             let meta =
                                 input.eat_meta().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(meta.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(meta));
                         }
                         "tt" => {
                             let token = input.eat().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(token.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(token));
                         }
                         "item" => {
                             let item =
                                 input.eat_item().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(item.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(item));
                         }
                         "lifetime" => {
                             let lifetime =
                                 input.eat_lifetime().ok_or(ExpandError::UnexpectedToken)?.clone();
-                            res.inner.insert(text.clone(), Binding::Simple(lifetime.into()));
+                            res.inner.insert(text.clone(), Binding::Simple(lifetime));
                         }
                         "literal" => {
                             let literal =
@@ -262,7 +260,7 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
                             // `vis` is optional
                             if let Some(vis) = input.try_eat_vis() {
                                 let vis = vis.clone();
-                                res.inner.insert(text.clone(), Binding::Simple(vis.into()));
+                                res.inner.insert(text.clone(), Binding::Simple(vis));
                             } else {
                                 res.push_optional(&text);
                             }
@@ -452,7 +450,7 @@ fn expand_tt(
 
                 let idx = ctx.nesting.pop().unwrap();
                 ctx.nesting.push(idx + 1);
-                token_trees.push(reduce_single_token(t).into());
+                token_trees.push(reduce_single_token(t));
 
                 if let Some(ref sep) = repeat.separator {
                     match sep {
diff --git a/crates/ra_mbe/src/mbe_parser.rs b/crates/ra_mbe/src/mbe_parser.rs
index d8fe293c7..dca16b537 100644
--- a/crates/ra_mbe/src/mbe_parser.rs
+++ b/crates/ra_mbe/src/mbe_parser.rs
@@ -125,8 +125,8 @@ fn parse_repeat(p: &mut TtCursor, transcriber: bool) -> Result<crate::Repeat, Pa
         }
     }
 
-    let sep = p.eat_seperator().ok_or(ParseError::Expected(String::from("separator")))?;
-    let rep = p.eat_punct().ok_or(ParseError::Expected(String::from("repeat")))?;
+    let sep = p.eat_seperator().ok_or_else(|| ParseError::Expected(String::from("separator")))?;
+    let rep = p.eat_punct().ok_or_else(|| ParseError::Expected(String::from("repeat")))?;
 
     mk_repeat(rep.char, subtree, Some(sep))
 }
diff --git a/crates/ra_mbe/src/syntax_bridge.rs b/crates/ra_mbe/src/syntax_bridge.rs
index 0edb6f9a2..cb039ca37 100644
--- a/crates/ra_mbe/src/syntax_bridge.rs
+++ b/crates/ra_mbe/src/syntax_bridge.rs
@@ -47,7 +47,7 @@ pub fn syntax_node_to_token_tree(node: &SyntaxNode) -> Option<(tt::Subtree, Toke
 
 fn token_tree_to_syntax_node<F>(tt: &tt::Subtree, f: F) -> Result<TreeArc<SyntaxNode>, ExpandError>
 where
-    F: Fn(&mut ra_parser::TokenSource, &mut ra_parser::TreeSink),
+    F: Fn(&mut dyn ra_parser::TokenSource, &mut dyn ra_parser::TreeSink),
 {
     let tokens = [tt.clone().into()];
     let buffer = TokenBuffer::new(&tokens);
@@ -155,9 +155,10 @@ fn convert_doc_comment<'a>(token: &ra_syntax::SyntaxToken<'a>) -> Option<Vec<tt:
     if let ast::CommentPlacement::Inner = doc {
         token_trees.push(mk_punct('!'));
     }
-    token_trees.push(tt::TokenTree::from(tt::Subtree::from(
-        tt::Subtree { delimiter: tt::Delimiter::Bracket, token_trees: meta_tkns }.into(),
-    )));
+    token_trees.push(tt::TokenTree::from(tt::Subtree {
+        delimiter: tt::Delimiter::Bracket,
+        token_trees: meta_tkns,
+    }));
 
     return Some(token_trees);
 
@@ -292,7 +293,7 @@ fn delim_to_str(d: tt::Delimiter, closing: bool) -> SmolStr {
     };
 
     let idx = closing as usize;
-    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 { "" };
     text.into()
 }
 
diff --git a/crates/ra_parser/src/grammar.rs b/crates/ra_parser/src/grammar.rs
index cf603eba1..5997636d6 100644
--- a/crates/ra_parser/src/grammar.rs
+++ b/crates/ra_parser/src/grammar.rs
@@ -87,10 +87,8 @@ pub(crate) fn pattern(p: &mut Parser) {
 }
 
 pub(crate) fn stmt(p: &mut Parser, with_semi: bool) {
-    let with_semi = match with_semi {
-        true => expressions::StmtWithSemi::Yes,
-        false => expressions::StmtWithSemi::No,
-    };
+    let with_semi =
+        if with_semi { expressions::StmtWithSemi::Yes } else { expressions::StmtWithSemi::No };
 
     expressions::stmt(p, with_semi)
 }
diff --git a/crates/ra_parser/src/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index bb6c78b5f..99e32c4e8 100644
--- a/crates/ra_parser/src/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
@@ -454,6 +454,7 @@ fn method_call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
 //     x.1i32;
 //     x.0x01;
 // }
+#[allow(clippy::if_same_then_else)]
 fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
     assert!(p.at(T![.]));
     let m = lhs.precede(p);
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index 8b1a1de49..725fb99f6 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -52,6 +52,7 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         CONTINUE_KW,
         LIFETIME,
         ASYNC_KW,
+        TRY_KW,
     ]);
 
 const EXPR_RECOVERY_SET: TokenSet = token_set![LET_KW];
@@ -75,6 +76,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
         T![loop] => loop_expr(p, None),
         T![for] => for_expr(p, None),
         T![while] => while_expr(p, None),
+        T![try] => try_block_expr(p, None),
         LIFETIME if la == T![:] => {
             let m = p.start();
             label(p);
@@ -116,7 +118,9 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
         }
     };
     let blocklike = match done.kind() {
-        IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR => BlockLike::Block,
+        IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR | TRY_BLOCK_EXPR => {
+            BlockLike::Block
+        }
         _ => BlockLike::NotBlock,
     };
     Some((done, blocklike))
@@ -491,3 +495,15 @@ fn break_expr(p: &mut Parser, r: Restrictions) -> CompletedMarker {
     }
     m.complete(p, BREAK_EXPR)
 }
+
+// test try_block_expr
+// fn foo() {
+//     let _ = try {};
+// }
+fn try_block_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+    assert!(p.at(T![try]));
+    let m = m.unwrap_or_else(|| p.start());
+    p.bump();
+    block(p);
+    m.complete(p, TRY_EXPR)
+}
diff --git a/crates/ra_parser/src/syntax_kind/generated.rs b/crates/ra_parser/src/syntax_kind/generated.rs
index d7926bd91..2c021f3e9 100644
--- a/crates/ra_parser/src/syntax_kind/generated.rs
+++ b/crates/ra_parser/src/syntax_kind/generated.rs
@@ -103,6 +103,7 @@ pub enum SyntaxKind {
     LET_KW,
     MOVE_KW,
     RETURN_KW,
+    TRY_KW,
     AUTO_KW,
     DEFAULT_KW,
     UNION_KW,
@@ -184,6 +185,7 @@ pub enum SyntaxKind {
     STRUCT_LIT,
     NAMED_FIELD_LIST,
     NAMED_FIELD,
+    TRY_BLOCK_EXPR,
     CALL_EXPR,
     INDEX_EXPR,
     METHOD_CALL_EXPR,
@@ -331,6 +333,7 @@ macro_rules! T {
     (let) => { $crate::SyntaxKind::LET_KW };
     (move) => { $crate::SyntaxKind::MOVE_KW };
     (return) => { $crate::SyntaxKind::RETURN_KW };
+    (try) => { $crate::SyntaxKind::TRY_KW };
     (auto) => { $crate::SyntaxKind::AUTO_KW };
     (default) => { $crate::SyntaxKind::DEFAULT_KW };
     (union) => { $crate::SyntaxKind::UNION_KW };
@@ -388,6 +391,7 @@ impl SyntaxKind {
             | LET_KW
             | MOVE_KW
             | RETURN_KW
+            | TRY_KW
             | AUTO_KW
             | DEFAULT_KW
             | UNION_KW
@@ -559,6 +563,7 @@ impl SyntaxKind {
             LET_KW => &SyntaxInfo { name: "LET_KW" },
             MOVE_KW => &SyntaxInfo { name: "MOVE_KW" },
             RETURN_KW => &SyntaxInfo { name: "RETURN_KW" },
+            TRY_KW => &SyntaxInfo { name: "TRY_KW" },
             AUTO_KW => &SyntaxInfo { name: "AUTO_KW" },
             DEFAULT_KW => &SyntaxInfo { name: "DEFAULT_KW" },
             UNION_KW => &SyntaxInfo { name: "UNION_KW" },
@@ -640,6 +645,7 @@ impl SyntaxKind {
             STRUCT_LIT => &SyntaxInfo { name: "STRUCT_LIT" },
             NAMED_FIELD_LIST => &SyntaxInfo { name: "NAMED_FIELD_LIST" },
             NAMED_FIELD => &SyntaxInfo { name: "NAMED_FIELD" },
+            TRY_BLOCK_EXPR => &SyntaxInfo { name: "TRY_BLOCK_EXPR" },
             CALL_EXPR => &SyntaxInfo { name: "CALL_EXPR" },
             INDEX_EXPR => &SyntaxInfo { name: "INDEX_EXPR" },
             METHOD_CALL_EXPR => &SyntaxInfo { name: "METHOD_CALL_EXPR" },
@@ -734,6 +740,7 @@ impl SyntaxKind {
             "let" => LET_KW,
             "move" => MOVE_KW,
             "return" => RETURN_KW,
+            "try" => TRY_KW,
             _ => return None,
         };
         Some(kw)
diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index efcce3d65..d55af18f5 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -8,3 +8,4 @@ publish = false
 [dependencies]
 once_cell = "0.2.0"
 itertools = "0.8.0"
+backtrace = "0.3.28"
diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index e681b8e0b..de67b4031 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -225,6 +225,36 @@ fn print(lvl: usize, msgs: &[Message], out: &mut impl Write, longer_than: Durati
     }
 }
 
+/// Prints backtrace to stderr, useful for debugging.
+pub fn print_backtrace() {
+    let bt = backtrace::Backtrace::new();
+    eprintln!("{:?}", bt);
+}
+
+thread_local!(static IN_SCOPE: RefCell<bool> = RefCell::new(false));
+
+/// Allows to check if the current code is withing some dynamic scope, can be
+/// useful during debugging to figure out why a function is called.
+pub struct Scope {
+    prev: bool,
+}
+
+impl Scope {
+    pub fn enter() -> Scope {
+        let prev = IN_SCOPE.with(|slot| std::mem::replace(&mut *slot.borrow_mut(), true));
+        Scope { prev }
+    }
+    pub fn is_active() -> bool {
+        IN_SCOPE.with(|slot| *slot.borrow())
+    }
+}
+
+impl Drop for Scope {
+    fn drop(&mut self) {
+        IN_SCOPE.with(|slot| *slot.borrow_mut() = self.prev);
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 71976071f..5a1657788 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -137,7 +137,7 @@ impl CargoWorkspace {
         for meta_pkg in meta.packages {
             let is_member = ws_members.contains(&meta_pkg.id);
             let pkg = packages.alloc(PackageData {
-                name: meta_pkg.name.into(),
+                name: meta_pkg.name,
                 manifest: meta_pkg.manifest_path.clone(),
                 targets: Vec::new(),
                 is_member,
@@ -149,7 +149,7 @@ impl CargoWorkspace {
             for meta_tgt in meta_pkg.targets {
                 let tgt = targets.alloc(TargetData {
                     pkg,
-                    name: meta_tgt.name.into(),
+                    name: meta_tgt.name,
                     root: meta_tgt.src_path.clone(),
                     kind: TargetKind::new(meta_tgt.kind.as_slice()),
                 });
@@ -160,8 +160,7 @@ impl CargoWorkspace {
         for node in resolve.nodes {
             let source = pkg_by_id[&node.id];
             for dep_node in node.deps {
-                let dep =
-                    PackageDependency { name: dep_node.name.into(), pkg: pkg_by_id[&dep_node.pkg] };
+                let dep = PackageDependency { name: dep_node.name, pkg: pkg_by_id[&dep_node.pkg] };
                 packages[source].dependencies.push(dep);
             }
         }
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 63eb7041e..4ae7f685c 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -70,7 +70,7 @@ impl ProjectRoot {
             })
         };
 
-        let hidden = dir_path.components().any(|c| c.as_str().starts_with("."));
+        let hidden = dir_path.components().any(|c| c.as_str().starts_with('.'));
 
         !is_ignored && !hidden
     }
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index e4c99784c..930b2d9fa 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -78,7 +78,7 @@ impl ast::Attr {
         if attr.kind() == IDENT {
             let key = attr.as_token()?.text().clone();
             let val_node = tt_node.children_with_tokens().find(|t| t.kind() == STRING)?;
-            let val = val_node.as_token()?.text().trim_start_matches("\"").trim_end_matches("\"");
+            let val = val_node.as_token()?.text().trim_start_matches('"').trim_end_matches('"');
             Some((key, SmolStr::new(val)))
         } else {
             None
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index e73fe22e9..1d888e709 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -713,6 +713,7 @@ pub enum ExprKind<'a> {
     MethodCallExpr(&'a MethodCallExpr),
     FieldExpr(&'a FieldExpr),
     TryExpr(&'a TryExpr),
+    TryBlockExpr(&'a TryBlockExpr),
     CastExpr(&'a CastExpr),
     RefExpr(&'a RefExpr),
     PrefixExpr(&'a PrefixExpr),
@@ -826,6 +827,11 @@ impl<'a> From<&'a TryExpr> for &'a Expr {
         Expr::cast(&n.syntax).unwrap()
     }
 }
+impl<'a> From<&'a TryBlockExpr> for &'a Expr {
+    fn from(n: &'a TryBlockExpr) -> &'a Expr {
+        Expr::cast(&n.syntax).unwrap()
+    }
+}
 impl<'a> From<&'a CastExpr> for &'a Expr {
     fn from(n: &'a CastExpr) -> &'a Expr {
         Expr::cast(&n.syntax).unwrap()
@@ -887,6 +893,7 @@ impl AstNode for Expr {
             | METHOD_CALL_EXPR
             | FIELD_EXPR
             | TRY_EXPR
+            | TRY_BLOCK_EXPR
             | CAST_EXPR
             | REF_EXPR
             | PREFIX_EXPR
@@ -929,6 +936,7 @@ impl Expr {
             METHOD_CALL_EXPR => ExprKind::MethodCallExpr(MethodCallExpr::cast(&self.syntax).unwrap()),
             FIELD_EXPR => ExprKind::FieldExpr(FieldExpr::cast(&self.syntax).unwrap()),
             TRY_EXPR => ExprKind::TryExpr(TryExpr::cast(&self.syntax).unwrap()),
+            TRY_BLOCK_EXPR => ExprKind::TryBlockExpr(TryBlockExpr::cast(&self.syntax).unwrap()),
             CAST_EXPR => ExprKind::CastExpr(CastExpr::cast(&self.syntax).unwrap()),
             REF_EXPR => ExprKind::RefExpr(RefExpr::cast(&self.syntax).unwrap()),
             PREFIX_EXPR => ExprKind::PrefixExpr(PrefixExpr::cast(&self.syntax).unwrap()),
@@ -3672,6 +3680,35 @@ impl TraitDef {
     }
 }
 
+// TryBlockExpr
+#[derive(Debug, PartialEq, Eq, Hash)]
+#[repr(transparent)]
+pub struct TryBlockExpr {
+    pub(crate) syntax: SyntaxNode,
+}
+unsafe impl TransparentNewType for TryBlockExpr {
+    type Repr = rowan::SyntaxNode;
+}
+
+impl AstNode for TryBlockExpr {
+    fn cast(syntax: &SyntaxNode) -> Option<&Self> {
+        match syntax.kind() {
+            TRY_BLOCK_EXPR => Some(TryBlockExpr::from_repr(syntax.into_repr())),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
+
+impl ToOwned for TryBlockExpr {
+    type Owned = TreeArc<TryBlockExpr>;
+    fn to_owned(&self) -> TreeArc<TryBlockExpr> { TreeArc::cast(self.syntax.to_owned()) }
+}
+
+
+impl ast::TryBlockBodyOwner for TryBlockExpr {}
+impl TryBlockExpr {}
+
 // TryExpr
 #[derive(Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index 1c90cf148..433485400 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -33,6 +33,12 @@ pub trait LoopBodyOwner: AstNode {
     }
 }
 
+pub trait TryBlockBodyOwner: AstNode {
+    fn try_body(&self) -> Option<&ast::Block> {
+        child_opt(self)
+    }
+}
+
 pub trait ArgListOwner: AstNode {
     fn arg_list(&self) -> Option<&ast::ArgList> {
         child_opt(self)
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index b8665bbc8..1c2714307 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -95,6 +95,7 @@ Grammar(
         "let",
         "move",
         "return",
+        "try",
     ],
     contextual_keywords: [
         "auto",
@@ -189,6 +190,7 @@ Grammar(
         "STRUCT_LIT",
         "NAMED_FIELD_LIST",
         "NAMED_FIELD",
+        "TRY_BLOCK_EXPR",
 
         // postfix
         "CALL_EXPR",
@@ -417,6 +419,9 @@ Grammar(
         "LoopExpr": (
             traits: ["LoopBodyOwner"],
         ),
+        "TryBlockExpr": (
+            traits: ["TryBlockBodyOwner"],
+        ),
         "ForExpr": (
             traits: ["LoopBodyOwner"],
             options: [
@@ -499,6 +504,7 @@ Grammar(
                 "MethodCallExpr",
                 "FieldExpr",
                 "TryExpr",
+                "TryBlockExpr",
                 "CastExpr",
                 "RefExpr",
                 "PrefixExpr",
diff --git a/crates/ra_syntax/src/parsing/lexer/numbers.rs b/crates/ra_syntax/src/parsing/lexer/numbers.rs
index 7f6abe1d5..874fb8b32 100644
--- a/crates/ra_syntax/src/parsing/lexer/numbers.rs
+++ b/crates/ra_syntax/src/parsing/lexer/numbers.rs
@@ -16,7 +16,7 @@ pub(crate) fn scan_number(c: char, ptr: &mut Ptr) -> SyntaxKind {
                 ptr.bump();
                 scan_digits(ptr, true);
             }
-            '0'...'9' | '_' | '.' | 'e' | 'E' => {
+            '0'..='9' | '_' | '.' | 'e' | 'E' => {
                 scan_digits(ptr, true);
             }
             _ => return INT_NUMBER,
@@ -47,10 +47,10 @@ pub(crate) fn scan_number(c: char, ptr: &mut Ptr) -> SyntaxKind {
 fn scan_digits(ptr: &mut Ptr, allow_hex: bool) {
     while let Some(c) = ptr.current() {
         match c {
-            '_' | '0'...'9' => {
+            '_' | '0'..='9' => {
                 ptr.bump();
             }
-            'a'...'f' | 'A'...'F' if allow_hex => {
+            'a'..='f' | 'A'..='F' if allow_hex => {
                 ptr.bump();
             }
             _ => return,
diff --git a/crates/ra_syntax/src/validation/unescape.rs b/crates/ra_syntax/src/validation/unescape.rs
index 2086046b6..91dbcfae8 100644
--- a/crates/ra_syntax/src/validation/unescape.rs
+++ b/crates/ra_syntax/src/validation/unescape.rs
@@ -255,7 +255,7 @@ where
         let first_non_space = str
             .bytes()
             .position(|b| b != b' ' && b != b'\t' && b != b'\n' && b != b'\r')
-            .unwrap_or(str.len());
+            .unwrap_or_else(|| str.len());
         *chars = str[first_non_space..].chars()
     }
 }
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.rs b/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.rs
new file mode 100644
index 000000000..0f1b41eb6
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.rs
@@ -0,0 +1,3 @@
+fn foo() {
+    let _ = try {};
+}
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.txt
new file mode 100644
index 000000000..53f49b9b5
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0130_try_block_expr.txt
@@ -0,0 +1,31 @@
+SOURCE_FILE@[0; 33)
+  FN_DEF@[0; 32)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 6)
+      IDENT@[3; 6) "foo"
+    PARAM_LIST@[6; 8)
+      L_PAREN@[6; 7) "("
+      R_PAREN@[7; 8) ")"
+    WHITESPACE@[8; 9) " "
+    BLOCK@[9; 32)
+      L_CURLY@[9; 10) "{"
+      WHITESPACE@[10; 15) "\n    "
+      LET_STMT@[15; 30)
+        LET_KW@[15; 18) "let"
+        WHITESPACE@[18; 19) " "
+        PLACEHOLDER_PAT@[19; 20)
+          UNDERSCORE@[19; 20) "_"
+        WHITESPACE@[20; 21) " "
+        EQ@[21; 22) "="
+        WHITESPACE@[22; 23) " "
+        TRY_EXPR@[23; 29)
+          TRY_KW@[23; 26) "try"
+          WHITESPACE@[26; 27) " "
+          BLOCK@[27; 29)
+            L_CURLY@[27; 28) "{"
+            R_CURLY@[28; 29) "}"
+        SEMI@[29; 30) ";"
+      WHITESPACE@[30; 31) "\n"
+      R_CURLY@[31; 32) "}"
+  WHITESPACE@[32; 33) "\n"
diff --git a/crates/ra_text_edit/src/test_utils.rs b/crates/ra_text_edit/src/test_utils.rs
index 9e21b24f6..2dc0e71af 100644
--- a/crates/ra_text_edit/src/test_utils.rs
+++ b/crates/ra_text_edit/src/test_utils.rs
@@ -42,8 +42,8 @@ pub fn arb_text_edit(text: &str) -> BoxedStrategy<TextEdit> {
         .prop_flat_map(|cuts| {
             let strategies: Vec<_> = cuts
                 .chunks(2)
-                .map(|chunk| match chunk {
-                    &[from, to] => {
+                .map(|chunk| match *chunk {
+                    [from, to] => {
                         let range = TextRange::from_to(from, to);
                         Just(AtomTextEdit::delete(range))
                             .boxed()
@@ -54,7 +54,7 @@ pub fn arb_text_edit(text: &str) -> BoxedStrategy<TextEdit> {
                             )
                             .boxed()
                     }
-                    &[x] => arb_text().prop_map(move |text| AtomTextEdit::insert(x, text)).boxed(),
+                    [x] => arb_text().prop_map(move |text| AtomTextEdit::insert(x, text)).boxed(),
                     _ => unreachable!(),
                 })
                 .collect();
diff --git a/crates/ra_tt/src/buffer.rs b/crates/ra_tt/src/buffer.rs
index 995c9f90b..5659aeae8 100644
--- a/crates/ra_tt/src/buffer.rs
+++ b/crates/ra_tt/src/buffer.rs
@@ -179,6 +179,6 @@ impl<'a> Cursor<'a> {
     /// Check whether it is a top level
     pub fn is_root(&self) -> bool {
         let entry_id = self.ptr.0;
-        return entry_id.0 == 0;
+        entry_id.0 == 0
     }
 }
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index 7f55779cf..8bb3b3937 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -318,7 +318,7 @@ pub fn project_dir() -> PathBuf {
 /// so this should always be correct.
 pub fn read_text(path: &Path) -> String {
     fs::read_to_string(path)
-        .expect(&format!("File at {:?} should be valid", path))
+        .unwrap_or_else(|_| panic!("File at {:?} should be valid", path))
         .replace("\r\n", "\n")
 }
 
diff --git a/crates/thread_worker/src/lib.rs b/crates/thread_worker/src/lib.rs
index d67e44e38..d8d0d9bf2 100644
--- a/crates/thread_worker/src/lib.rs
+++ b/crates/thread_worker/src/lib.rs
@@ -19,13 +19,10 @@ impl Drop for ScopedThread {
         log::info!(".. {} terminated with {}", name, if res.is_ok() { "ok" } else { "err" });
 
         // escalate panic, but avoid aborting the process
-        match res {
-            Err(e) => {
-                if !thread::panicking() {
-                    panic!(e)
-                }
+        if let Err(e) = res {
+            if !thread::panicking() {
+                panic!(e)
             }
-            _ => (),
         }
     }
 }
diff --git a/crates/tools/src/lib.rs b/crates/tools/src/lib.rs
index 11b52ccb7..2446fdf28 100644
--- a/crates/tools/src/lib.rs
+++ b/crates/tools/src/lib.rs
@@ -133,6 +133,40 @@ pub fn install_format_hook() -> Result<()> {
     Ok(())
 }
 
+pub fn run_clippy() -> Result<()> {
+    match Command::new("rustup")
+        .args(&["run", TOOLCHAIN, "--", "cargo", "clippy", "--version"])
+        .stderr(Stdio::null())
+        .stdout(Stdio::null())
+        .status()
+    {
+        Ok(status) if status.success() => (),
+        _ => install_clippy()?,
+    };
+
+    let allowed_lints = [
+        "clippy::collapsible_if",
+        "clippy::map_clone", // FIXME: remove when Iterator::copied stabilizes (1.36.0)
+        "clippy::needless_pass_by_value",
+        "clippy::nonminimal_bool",
+        "clippy::redundant_pattern_matching",
+    ];
+    run(
+        &format!(
+            "rustup run {} -- cargo clippy --all-features --all-targets -- -A {}",
+            TOOLCHAIN,
+            allowed_lints.join(" -A ")
+        ),
+        ".",
+    )?;
+    Ok(())
+}
+
+pub fn install_clippy() -> Result<()> {
+    run(&format!("rustup install {}", TOOLCHAIN), ".")?;
+    run(&format!("rustup component add clippy --toolchain {}", TOOLCHAIN), ".")
+}
+
 pub fn run_fuzzer() -> Result<()> {
     match Command::new("cargo")
         .args(&["fuzz", "--help"])
diff --git a/crates/tools/src/main.rs b/crates/tools/src/main.rs
index 0c3339685..8027ff833 100644
--- a/crates/tools/src/main.rs
+++ b/crates/tools/src/main.rs
@@ -3,7 +3,7 @@ use core::str;
 use failure::bail;
 use tools::{
     generate, gen_tests, install_format_hook, run, run_with_output, run_rustfmt,
-    Overwrite, Result, run_fuzzer,
+    Overwrite, Result, run_fuzzer, run_clippy,
 };
 use std::{path::{PathBuf}, env};
 
@@ -16,6 +16,7 @@ fn main() -> Result<()> {
         .subcommand(SubCommand::with_name("format"))
         .subcommand(SubCommand::with_name("format-hook"))
         .subcommand(SubCommand::with_name("fuzz-tests"))
+        .subcommand(SubCommand::with_name("lint"))
         .get_matches();
     match matches.subcommand_name().expect("Subcommand must be specified") {
         "install-code" => {
@@ -28,6 +29,7 @@ fn main() -> Result<()> {
         "gen-syntax" => generate(Overwrite)?,
         "format" => run_rustfmt(Overwrite)?,
         "format-hook" => install_format_hook()?,
+        "lint" => run_clippy()?,
         "fuzz-tests" => run_fuzzer()?,
         _ => unreachable!(),
     }
@@ -82,7 +84,7 @@ fn fix_path_for_mac() -> Result<()> {
 
         [ROOT_DIR, &home_dir]
             .iter()
-            .map(|dir| String::from(dir.clone()) + COMMON_APP_PATH)
+            .map(|dir| String::from(*dir) + COMMON_APP_PATH)
             .map(PathBuf::from)
             .filter(|path| path.exists())
             .collect()