19 files changed, 66 insertions, 80 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index b7eabaabb..88490fea9 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -219,8 +219,7 @@ impl Crate {
         let doc_url = doc_attr_q.tt_values().map(|tt| {
             let name = tt.token_trees.iter()
                 .skip_while(|tt| !matches!(tt, TokenTree::Leaf(Leaf::Ident(Ident{text: ref ident, ..})) if ident == "html_root_url"))
-                .skip(2)
-                .next();
+                .nth(2);
 
             match name {
                 Some(TokenTree::Leaf(Leaf::Literal(Literal{ref text, ..}))) => Some(text),
@@ -1846,7 +1845,7 @@ impl TypeParam {
 
     pub fn trait_bounds(self, db: &dyn HirDatabase) -> Vec<Trait> {
         db.generic_predicates_for_param(self.id)
-            .into_iter()
+            .iter()
             .filter_map(|pred| match &pred.skip_binders().skip_binders() {
                 hir_ty::WhereClause::Implemented(trait_ref) => {
                     Some(Trait::from(trait_ref.hir_trait_id()))
@@ -1951,7 +1950,7 @@ impl Impl {
             all.extend(
                 db.inherent_impls_in_crate(id)
                     .for_self_ty(&ty)
-                    .into_iter()
+                    .iter()
                     .cloned()
                     .map(Self::from)
                     .filter(filter),
@@ -2232,8 +2231,8 @@ impl Type {
     }
 
     pub fn is_packed(&self, db: &dyn HirDatabase) -> bool {
-        let adt_id = match self.ty.kind(&Interner) {
-            &TyKind::Adt(hir_ty::AdtId(adt_id), ..) => adt_id,
+        let adt_id = match *self.ty.kind(&Interner) {
+            TyKind::Adt(hir_ty::AdtId(adt_id), ..) => adt_id,
             _ => return false,
         };
 
@@ -2287,9 +2286,9 @@ impl Type {
     }
 
     pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
-        let (variant_id, substs) = match self.ty.kind(&Interner) {
-            &TyKind::Adt(hir_ty::AdtId(AdtId::StructId(s)), ref substs) => (s.into(), substs),
-            &TyKind::Adt(hir_ty::AdtId(AdtId::UnionId(u)), ref substs) => (u.into(), substs),
+        let (variant_id, substs) = match *self.ty.kind(&Interner) {
+            TyKind::Adt(hir_ty::AdtId(AdtId::StructId(s)), ref substs) => (s.into(), substs),
+            TyKind::Adt(hir_ty::AdtId(AdtId::UnionId(u)), ref substs) => (u.into(), substs),
             _ => return Vec::new(),
         };
 
@@ -2488,20 +2487,17 @@ impl Type {
             cb: &mut impl FnMut(Type),
         ) {
             for pred in bounds {
-                match pred.skip_binders() {
-                    WhereClause::Implemented(trait_ref) => {
-                        cb(type_.clone());
-                        // skip the self type. it's likely the type we just got the bounds from
-                        for ty in trait_ref
-                            .substitution
-                            .iter(&Interner)
-                            .skip(1)
-                            .filter_map(|a| a.ty(&Interner))
-                        {
-                            walk_type(db, &type_.derived(ty.clone()), cb);
-                        }
+                if let WhereClause::Implemented(trait_ref) = pred.skip_binders() {
+                    cb(type_.clone());
+                    // skip the self type. it's likely the type we just got the bounds from
+                    for ty in trait_ref
+                        .substitution
+                        .iter(&Interner)
+                        .skip(1)
+                        .filter_map(|a| a.ty(&Interner))
+                    {
+                        walk_type(db, &type_.derived(ty.clone()), cb);
                     }
-                    _ => (),
                 }
             }
         }
@@ -2514,7 +2510,7 @@ impl Type {
                     walk_substs(db, type_, substs, cb);
                 }
                 TyKind::AssociatedType(_, substs) => {
-                    if let Some(_) = ty.associated_type_parent_trait(db) {
+                    if ty.associated_type_parent_trait(db).is_some() {
                         cb(type_.derived(ty.clone()));
                     }
                     walk_substs(db, type_, substs, cb);
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index bed4c4994..f6e6cdbe2 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -690,9 +690,7 @@ impl ExprCollector<'_> {
                 }
             }
             ast::Stmt::Item(item) => {
-                if self.check_cfg(&item).is_none() {
-                    return;
-                }
+                self.check_cfg(&item);
             }
         }
     }
@@ -717,7 +715,8 @@ impl ExprCollector<'_> {
         block.statements().for_each(|s| self.collect_stmt(s));
         block.tail_expr().and_then(|e| {
             let expr = self.maybe_collect_expr(e)?;
-            Some(self.statements_in_scope.push(Statement::Expr { expr, has_semi: false }))
+            self.statements_in_scope.push(Statement::Expr { expr, has_semi: false });
+            Some(())
         });
 
         let mut tail = None;
diff --git a/crates/hir_def/src/body/tests.rs b/crates/hir_def/src/body/tests.rs
index 27d837d47..673a75386 100644
--- a/crates/hir_def/src/body/tests.rs
+++ b/crates/hir_def/src/body/tests.rs
@@ -15,12 +15,9 @@ fn lower(ra_fixture: &str) -> Arc<Body> {
     let mut fn_def = None;
     'outer: for (_, module) in def_map.modules() {
         for decl in module.scope.declarations() {
-            match decl {
-                ModuleDefId::FunctionId(it) => {
-                    fn_def = Some(it);
-                    break 'outer;
-                }
-                _ => {}
+            if let ModuleDefId::FunctionId(it) = decl {
+                fn_def = Some(it);
+                break 'outer;
             }
         }
     }
diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index 0f04b2bae..096ac7968 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -104,7 +104,7 @@ impl GenericParams {
     ) -> Interned<GenericParams> {
         let _p = profile::span("generic_params_query");
 
-        let generics = match def {
+        match def {
             GenericDefId::FunctionId(id) => {
                 let id = id.lookup(db).id;
                 let tree = id.item_tree(db);
@@ -150,8 +150,7 @@ impl GenericParams {
             GenericDefId::EnumVariantId(_) | GenericDefId::ConstId(_) => {
                 Interned::new(GenericParams::default())
             }
-        };
-        generics
+        }
     }
 
     fn new(db: &dyn DefDatabase, def: GenericDefId) -> (GenericParams, InFile<SourceMap>) {
diff --git a/crates/hir_def/src/item_scope.rs b/crates/hir_def/src/item_scope.rs
index 08407ebfa..567ae5660 100644
--- a/crates/hir_def/src/item_scope.rs
+++ b/crates/hir_def/src/item_scope.rs
@@ -241,10 +241,8 @@ impl ItemScope {
         check_changed!(changed, (self / def).values, glob_imports[lookup], def_import_type);
         check_changed!(changed, (self / def).macros, glob_imports[lookup], def_import_type);
 
-        if def.is_none() {
-            if self.unresolved.insert(lookup.1) {
-                changed = true;
-            }
+        if def.is_none() && self.unresolved.insert(lookup.1) {
+            changed = true;
         }
 
         changed
diff --git a/crates/hir_def/src/item_tree/pretty.rs b/crates/hir_def/src/item_tree/pretty.rs
index e63bc8232..8b12e5a67 100644
--- a/crates/hir_def/src/item_tree/pretty.rs
+++ b/crates/hir_def/src/item_tree/pretty.rs
@@ -30,16 +30,16 @@ pub(super) fn print_item_tree(tree: &ItemTree) -> String {
 
 macro_rules! w {
     ($dst:expr, $($arg:tt)*) => {
-        drop(write!($dst, $($arg)*))
+        { let _ = write!($dst, $($arg)*); }
     };
 }
 
 macro_rules! wln {
     ($dst:expr) => {
-        drop(writeln!($dst))
+        { let _ = writeln!($dst); }
     };
     ($dst:expr, $($arg:tt)*) => {
-        drop(writeln!($dst, $($arg)*))
+        { let _ = writeln!($dst, $($arg)*); }
     };
 }
 
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index ebfcc26c4..9e6aa9607 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -367,10 +367,7 @@ impl DefMap {
     pub fn containing_module(&self, local_mod: LocalModuleId) -> Option<ModuleId> {
         match &self[local_mod].parent {
             Some(parent) => Some(self.module_id(*parent)),
-            None => match &self.block {
-                Some(block) => Some(block.parent),
-                None => None,
-            },
+            None => self.block.as_ref().map(|block| block.parent),
         }
     }
 
diff --git a/crates/hir_def/src/nameres/path_resolution.rs b/crates/hir_def/src/nameres/path_resolution.rs
index 629bc7952..229f57d77 100644
--- a/crates/hir_def/src/nameres/path_resolution.rs
+++ b/crates/hir_def/src/nameres/path_resolution.rs
@@ -55,7 +55,7 @@ impl ResolvePathResult {
         segment_index: Option<usize>,
         krate: Option<CrateId>,
     ) -> ResolvePathResult {
-        ResolvePathResult { resolved_def, reached_fixedpoint, segment_index, krate }
+        ResolvePathResult { resolved_def, segment_index, reached_fixedpoint, krate }
     }
 }
 
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index 4cdb5913d..667092cd2 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -209,7 +209,7 @@ impl Path {
 
     pub fn is_self_type(&self) -> bool {
         self.type_anchor.is_none()
-            && self.generic_args == &[None]
+            && self.generic_args == [None]
             && self.mod_path.as_ident() == Some(&name!(Self))
     }
 }
diff --git a/crates/hir_def/src/resolver.rs b/crates/hir_def/src/resolver.rs
index 49c573087..a11439c3b 100644
--- a/crates/hir_def/src/resolver.rs
+++ b/crates/hir_def/src/resolver.rs
@@ -388,9 +388,9 @@ impl Resolver {
         self.module_scope().map(|t| t.0.krate())
     }
 
-    pub fn where_predicates_in_scope<'a>(
-        &'a self,
-    ) -> impl Iterator<Item = &'a crate::generics::WherePredicate> + 'a {
+    pub fn where_predicates_in_scope(
+        &self,
+    ) -> impl Iterator<Item = &crate::generics::WherePredicate> {
         self.scopes
             .iter()
             .rev()
@@ -464,16 +464,16 @@ impl Scope {
             &Scope::GenericParams { ref params, def: parent } => {
                 for (local_id, param) in params.types.iter() {
                     if let Some(ref name) = param.name {
-                        let id = TypeParamId { local_id, parent };
+                        let id = TypeParamId { parent, local_id };
                         f(name.clone(), ScopeDef::GenericParam(id.into()))
                     }
                 }
                 for (local_id, param) in params.consts.iter() {
-                    let id = ConstParamId { local_id, parent };
+                    let id = ConstParamId { parent, local_id };
                     f(param.name.clone(), ScopeDef::GenericParam(id.into()))
                 }
                 for (local_id, param) in params.lifetimes.iter() {
-                    let id = LifetimeParamId { local_id, parent };
+                    let id = LifetimeParamId { parent, local_id };
                     f(param.name.clone(), ScopeDef::GenericParam(id.into()))
                 }
             }
diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
index 4c83a2efe..f556bc751 100644
--- a/crates/hir_expand/src/builtin_macro.rs
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -420,7 +420,7 @@ fn parse_string(tt: &tt::Subtree) -> Result<String, mbe::ExpandError> {
             tt::TokenTree::Leaf(tt::Leaf::Literal(it)) => unquote_str(it),
             _ => None,
         })
-        .ok_or_else(|| mbe::ExpandError::ConversionError)
+        .ok_or(mbe::ExpandError::ConversionError)
 }
 
 fn include_expand(
@@ -432,9 +432,8 @@ fn include_expand(
         let path = parse_string(tt)?;
         let file_id = relative_file(db, arg_id, &path, false)?;
 
-        let subtree = parse_to_token_tree(&db.file_text(file_id))
-            .ok_or_else(|| mbe::ExpandError::ConversionError)?
-            .0;
+        let subtree =
+            parse_to_token_tree(&db.file_text(file_id)).ok_or(mbe::ExpandError::ConversionError)?.0;
         Ok((subtree, file_id))
     })();
 
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 584ddcf9f..66601f4df 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -128,7 +128,7 @@ pub fn expand_eager_macro(
         }),
         kind: MacroCallKind::FnLike { ast_id: call_id, fragment: FragmentKind::Expr },
     });
-    let arg_file_id: MacroCallId = arg_id;
+    let arg_file_id = arg_id;
 
     let parsed_args =
         diagnostic_sink.result(mbe::token_tree_to_syntax_node(&parsed_args, FragmentKind::Expr))?.0;
@@ -177,7 +177,7 @@ fn lazy_expand(
     let ast_id = db.ast_id_map(macro_call.file_id).ast_id(&macro_call.value);
 
     let fragment = crate::to_fragment_kind(&macro_call.value);
-    let id: MacroCallId = def.as_lazy_macro(
+    let id = def.as_lazy_macro(
         db,
         krate,
         MacroCallKind::FnLike { ast_id: macro_call.with_value(ast_id), fragment },
@@ -207,7 +207,7 @@ fn eager_macro_recur(
             .option_with(|| macro_resolver(child.path()?), || err("failed to resolve macro"))?;
         let insert = match def.kind {
             MacroDefKind::BuiltInEager(..) => {
-                let id: MacroCallId = expand_eager_macro(
+                let id = expand_eager_macro(
                     db,
                     krate,
                     curr.with_value(child.clone()),
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs
index b4f2fe9a4..0d694b1a7 100644
--- a/crates/mbe/src/expander/matcher.rs
+++ b/crates/mbe/src/expander/matcher.rs
@@ -645,7 +645,7 @@ fn match_loop(pattern: &MetaTemplate, src: &tt::Subtree) -> Match {
                     None if match_res.err.is_none() => {
                         bindings_builder.push_optional(&mut item.bindings, name);
                     }
-                    _ => {}
+                    None => {}
                 }
                 if let Some(err) = match_res.err {
                     res.add_err(err);
@@ -756,7 +756,7 @@ impl<'a> TtIter<'a> {
         let ok = match separator {
             Separator::Ident(lhs) if idx == 0 => match fork.expect_ident_or_underscore() {
                 Ok(rhs) => rhs.text == lhs.text,
-                _ => false,
+                Err(_) => false,
             },
             Separator::Literal(lhs) if idx == 0 => match fork.expect_literal() {
                 Ok(rhs) => match rhs {
@@ -764,11 +764,11 @@ impl<'a> TtIter<'a> {
                     tt::Leaf::Ident(rhs) => rhs.text == lhs.text,
                     tt::Leaf::Punct(_) => false,
                 },
-                _ => false,
+                Err(_) => false,
             },
             Separator::Puncts(lhss) if idx < lhss.len() => match fork.expect_punct() {
                 Ok(rhs) => rhs.char == lhss[idx].char,
-                _ => false,
+                Err(_) => false,
             },
             _ => false,
         };
diff --git a/crates/mbe/src/expander/transcriber.rs b/crates/mbe/src/expander/transcriber.rs
index 49a137577..4894e2a0c 100644
--- a/crates/mbe/src/expander/transcriber.rs
+++ b/crates/mbe/src/expander/transcriber.rs
@@ -241,6 +241,6 @@ fn push_fragment(buf: &mut Vec<tt::TokenTree>, fragment: Fragment) {
 fn push_subtree(buf: &mut Vec<tt::TokenTree>, tt: tt::Subtree) {
     match tt.delimiter {
         None => buf.extend(tt.token_trees),
-        _ => buf.push(tt.into()),
+        Some(_) => buf.push(tt.into()),
     }
 }
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index 8c8528aaf..fcc596756 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -135,7 +135,7 @@ impl Shift {
 
     /// Shift given TokenTree token id
     fn shift_all(self, tt: &mut tt::Subtree) {
-        for t in tt.token_trees.iter_mut() {
+        for t in &mut tt.token_trees {
             match t {
                 tt::TokenTree::Leaf(leaf) => match leaf {
                     tt::Leaf::Ident(ident) => ident.id = self.shift(ident.id),
@@ -188,7 +188,7 @@ impl MacroRules {
             }
         }
 
-        for rule in rules.iter() {
+        for rule in &rules {
             validate(&rule.lhs)?;
         }
 
@@ -241,7 +241,7 @@ impl MacroDef {
             }
             rules.push(rule);
         }
-        for rule in rules.iter() {
+        for rule in &rules {
             validate(&rule.lhs)?;
         }
 
@@ -268,7 +268,7 @@ impl MacroDef {
 }
 
 impl Rule {
-    fn parse(src: &mut TtIter, expect_arrow: bool) -> Result<Rule, ParseError> {
+    fn parse(src: &mut TtIter, expect_arrow: bool) -> Result<Self, ParseError> {
         let lhs = src
             .expect_subtree()
             .map_err(|()| ParseError::Expected("expected subtree".to_string()))?;
@@ -356,7 +356,7 @@ impl<T> ExpandResult<T> {
     }
 
     pub fn result(self) -> Result<T, ExpandError> {
-        self.err.map(Err).unwrap_or(Ok(self.value))
+        self.err.map_or(Ok(self.value), Err)
     }
 }
 
diff --git a/crates/mbe/src/subtree_source.rs b/crates/mbe/src/subtree_source.rs
index ee80807ad..ffc2a6017 100644
--- a/crates/mbe/src/subtree_source.rs
+++ b/crates/mbe/src/subtree_source.rs
@@ -115,7 +115,7 @@ impl<'a> TokenSource for SubtreeTokenSource {
     fn is_keyword(&self, kw: &str) -> bool {
         match self.cached.get(self.curr.1) {
             Some(t) => t.text == *kw,
-            _ => false,
+            None => false,
         }
     }
 }
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index cdc22425d..7526bd8e6 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -283,7 +283,7 @@ trait TokenConvertor {
                 let (id, idx) = self.id_alloc().open_delim(range);
                 subtree.delimiter = Some(tt::Delimiter { id, kind });
 
-                while self.peek().map(|it| it.kind() != closed).unwrap_or(false) {
+                while self.peek().map_or(false, |it| it.kind() != closed) {
                     self.collect_leaf(&mut subtree.token_trees);
                 }
                 let last_range = match self.bump() {
diff --git a/crates/mbe/src/tt_iter.rs b/crates/mbe/src/tt_iter.rs
index 5a4eca7bf..65da83476 100644
--- a/crates/mbe/src/tt_iter.rs
+++ b/crates/mbe/src/tt_iter.rs
@@ -121,10 +121,11 @@ impl<'a> TtIter<'a> {
 
         parser::parse_fragment(&mut src, &mut sink, fragment_kind);
 
-        let mut err = None;
-        if !sink.cursor.is_root() || sink.error {
-            err = Some(err!("expected {:?}", fragment_kind));
-        }
+        let mut err = if !sink.cursor.is_root() || sink.error {
+            Some(err!("expected {:?}", fragment_kind))
+        } else {
+            None
+        };
 
         let mut curr = buffer.begin();
         let mut res = vec![];
diff --git a/crates/proc_macro_srv/src/rustc_server.rs b/crates/proc_macro_srv/src/rustc_server.rs
index 65ca3eb6c..e252e89a5 100644
--- a/crates/proc_macro_srv/src/rustc_server.rs
+++ b/crates/proc_macro_srv/src/rustc_server.rs
@@ -248,7 +248,7 @@ pub mod token_stream {
             token_trees: subtree
                 .token_trees
                 .into_iter()
-                .map(|t| token_tree_replace_token_ids_with_unspecified(t))
+                .map(token_tree_replace_token_ids_with_unspecified)
                 .collect(),
         }
     }
@@ -457,7 +457,7 @@ impl server::Group for Rustc {
     }
 
     fn span(&mut self, group: &Self::Group) -> Self::Span {
-        group.delimiter.map(|it| it.id).unwrap_or_else(|| tt::TokenId::unspecified())
+        group.delimiter.map(|it| it.id).unwrap_or_else(tt::TokenId::unspecified)
     }
 
     fn set_span(&mut self, _group: &mut Self::Group, _span: Self::Span) {