Merge #1374

1374: Implement `cargo lint` and fix some clippy errors r=alanhdu a=alanhdu

This creates a `cargo lint` command that runs clippy with certain lints disabled. I've also gone ahead and fixed some of the lint errors, although there are many more still to go.

cc #848 

Co-authored-by: Alan Du <[email protected]>

15 files changed, 73 insertions, 95 deletions

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/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..905fe9f0e 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(_) => {}
                 }
-                _ => {}
-            },
-            _ => {}
+            }
         }
     }
 
@@ -1049,7 +1044,7 @@ 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));
     }