18 files changed, 543 insertions, 283 deletions

diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
index 664894d1f..26b3c813a 100644
--- a/crates/ra_syntax/src/algo.rs
+++ b/crates/ra_syntax/src/algo.rs
@@ -41,6 +41,10 @@ pub fn find_node_at_offset<N: AstNode>(syntax: &SyntaxNode, offset: TextSize) ->
     ancestors_at_offset(syntax, offset).find_map(N::cast)
 }
 
+pub fn find_node_at_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
+    find_covering_element(syntax, range).ancestors().find_map(N::cast)
+}
+
 /// Skip to next non `trivia` token
 pub fn skip_trivia_token(mut token: SyntaxToken, direction: Direction) -> Option<SyntaxToken> {
     while token.kind().is_trivia() {
@@ -290,6 +294,11 @@ impl<'a> SyntaxRewriter<'a> {
         N::cast(self.rewrite(node.syntax())).unwrap()
     }
 
+    /// Returns a node that encompasses all replacements to be done by this rewriter.
+    ///
+    /// Passing the returned node to `rewrite` will apply all replacements queued up in `self`.
+    ///
+    /// Returns `None` when there are no replacements.
     pub fn rewrite_root(&self) -> Option<SyntaxNode> {
         assert!(self.f.is_none());
         self.replacements
@@ -298,6 +307,9 @@ impl<'a> SyntaxRewriter<'a> {
                 SyntaxElement::Node(it) => it.clone(),
                 SyntaxElement::Token(it) => it.parent(),
             })
+            // If we only have one replacement, we must return its parent node, since `rewrite` does
+            // not replace the node passed to it.
+            .map(|it| it.parent().unwrap_or(it))
             .fold1(|a, b| least_common_ancestor(&a, &b).unwrap())
     }
 
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 1876afe95..9d02aeef3 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -75,7 +75,7 @@ impl<N> AstChildren<N> {
 impl<N: AstNode> Iterator for AstChildren<N> {
     type Item = N;
     fn next(&mut self) -> Option<N> {
-        self.inner.by_ref().find_map(N::cast)
+        self.inner.find_map(N::cast)
     }
 }
 
@@ -285,6 +285,8 @@ where
     let pred = predicates.next().unwrap();
     let mut bounds = pred.type_bound_list().unwrap().bounds();
 
+    assert!(pred.for_token().is_none());
+    assert!(pred.type_param_list().is_none());
     assert_eq!("T", pred.type_ref().unwrap().syntax().text().to_string());
     assert_bound("Clone", bounds.next());
     assert_bound("Copy", bounds.next());
@@ -322,6 +324,8 @@ where
     let pred = predicates.next().unwrap();
     let mut bounds = pred.type_bound_list().unwrap().bounds();
 
-    assert_eq!("for<'a> F", pred.type_ref().unwrap().syntax().text().to_string());
+    assert!(pred.for_token().is_some());
+    assert_eq!("<'a>", pred.type_param_list().unwrap().syntax().text().to_string());
+    assert_eq!("F", pred.type_ref().unwrap().syntax().text().to_string());
     assert_bound("Fn(&'a str)", bounds.next());
 }
diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 29eb3fcb9..abc7a646c 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -189,6 +189,21 @@ impl ast::RecordFieldList {
     }
 }
 
+impl ast::TypeAliasDef {
+    #[must_use]
+    pub fn remove_bounds(&self) -> ast::TypeAliasDef {
+        let colon = match self.colon_token() {
+            Some(it) => it,
+            None => return self.clone(),
+        };
+        let end = match self.type_bound_list() {
+            Some(it) => it.syntax().clone().into(),
+            None => colon.clone().into(),
+        };
+        self.replace_children(colon.into()..=end, iter::empty())
+    }
+}
+
 impl ast::TypeParam {
     #[must_use]
     pub fn remove_bounds(&self) -> ast::TypeParam {
@@ -299,12 +314,8 @@ impl ast::UseTree {
             Some(it) => it,
             None => return self.clone(),
         };
-        let use_tree = make::use_tree(
-            suffix.clone(),
-            self.use_tree_list(),
-            self.alias(),
-            self.star_token().is_some(),
-        );
+        let use_tree =
+            make::use_tree(suffix, self.use_tree_list(), self.alias(), self.star_token().is_some());
         let nested = make::use_tree_list(iter::once(use_tree));
         return make::use_tree(prefix.clone(), Some(nested), None, false);
 
@@ -579,12 +590,17 @@ pub trait AstNodeEdit: AstNode + Clone + Sized {
         rewriter.rewrite_ast(self)
     }
     #[must_use]
-    fn indent(&self, indent: IndentLevel) -> Self {
-        Self::cast(indent.increase_indent(self.syntax().clone())).unwrap()
+    fn indent(&self, level: IndentLevel) -> Self {
+        Self::cast(level.increase_indent(self.syntax().clone())).unwrap()
+    }
+    #[must_use]
+    fn dedent(&self, level: IndentLevel) -> Self {
+        Self::cast(level.decrease_indent(self.syntax().clone())).unwrap()
     }
     #[must_use]
-    fn dedent(&self, indent: IndentLevel) -> Self {
-        Self::cast(indent.decrease_indent(self.syntax().clone())).unwrap()
+    fn reset_indent(&self) -> Self {
+        let level = IndentLevel::from_node(self.syntax());
+        self.dedent(level)
     }
 }
 
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 7771d6759..db5438d68 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -399,10 +399,7 @@ impl ast::BlockExpr {
             Some(it) => it,
             None => return true,
         };
-        match parent.kind() {
-            FN_DEF | IF_EXPR | WHILE_EXPR | LOOP_EXPR | EFFECT_EXPR => false,
-            _ => true,
-        }
+        !matches!(parent.kind(), FN_DEF | IF_EXPR | WHILE_EXPR | LOOP_EXPR | EFFECT_EXPR)
     }
 }
 
diff --git a/crates/ra_syntax/src/ast/extensions.rs b/crates/ra_syntax/src/ast/extensions.rs
index 98c38d009..662c6f73e 100644
--- a/crates/ra_syntax/src/ast/extensions.rs
+++ b/crates/ra_syntax/src/ast/extensions.rs
@@ -459,16 +459,16 @@ impl ast::RangePat {
 
 impl ast::TokenTree {
     pub fn left_delimiter_token(&self) -> Option<SyntaxToken> {
-        self.syntax().first_child_or_token()?.into_token().filter(|it| match it.kind() {
-            T!['{'] | T!['('] | T!['['] => true,
-            _ => false,
-        })
+        self.syntax()
+            .first_child_or_token()?
+            .into_token()
+            .filter(|it| matches!(it.kind(), T!['{'] | T!['('] | T!['[']))
     }
 
     pub fn right_delimiter_token(&self) -> Option<SyntaxToken> {
-        self.syntax().last_child_or_token()?.into_token().filter(|it| match it.kind() {
-            T!['}'] | T![')'] | T![']'] => true,
-            _ => false,
-        })
+        self.syntax()
+            .last_child_or_token()?
+            .into_token()
+            .filter(|it| matches!(it.kind(), T!['}'] | T![')'] | T![']']))
     }
 }
diff --git a/crates/ra_syntax/src/ast/generated/nodes.rs b/crates/ra_syntax/src/ast/generated/nodes.rs
index cb430ca01..58141da11 100644
--- a/crates/ra_syntax/src/ast/generated/nodes.rs
+++ b/crates/ra_syntax/src/ast/generated/nodes.rs
@@ -2052,6 +2052,8 @@ pub struct WherePred {
 }
 impl ast::TypeBoundsOwner for WherePred {}
 impl WherePred {
+    pub fn for_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![for]) }
+    pub fn type_param_list(&self) -> Option<TypeParamList> { support::child(&self.syntax) }
     pub fn lifetime_token(&self) -> Option<SyntaxToken> {
         support::token(&self.syntax, T![lifetime])
     }
@@ -4849,687 +4851,687 @@ impl AstNode for FieldDefList {
     }
 }
 impl std::fmt::Display for NominalDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for GenericParam {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for GenericArg {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeRef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ModuleItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for AssocItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ExternItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Expr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Pat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordInnerPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for AttrInput {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Stmt {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for FieldDefList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for SourceFile {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for FnDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RetType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for StructDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for UnionDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordFieldDefList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordFieldDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TupleFieldDefList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TupleFieldDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for EnumDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for EnumVariantList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for EnumVariant {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TraitDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Module {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ItemList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ConstDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for StaticDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeAliasDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ImplDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ParenType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TupleType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for NeverType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PathType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PointerType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ArrayType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for SliceType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ReferenceType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PlaceholderType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for FnPointerType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ForType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ImplTraitType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for DynTraitType {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TupleExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ArrayExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ParenExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PathExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LambdaExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for IfExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LoopExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for EffectExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ForExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for WhileExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ContinueExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BreakExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Label {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BlockExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ReturnExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for CallExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MethodCallExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for IndexExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for FieldExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for AwaitExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TryExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for CastExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RefExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PrefixExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BoxExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RangeExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BinExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Literal {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MatchExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MatchArmList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MatchArm {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MatchGuard {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordLit {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordFieldList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordField {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for OrPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ParenPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RefPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BoxPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for BindPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PlaceholderPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for DotDotPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PathPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for SlicePat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RangePat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LiteralPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MacroPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordFieldPatList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for RecordFieldPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TupleStructPat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TuplePat {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Visibility {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Name {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for NameRef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MacroCall {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Attr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TokenTree {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeParamList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeParam {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ConstParam {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LifetimeParam {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeBound {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeBoundList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for WherePred {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for WhereClause {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Abi {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ExprStmt {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LetStmt {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Condition {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ParamList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for SelfParam {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Param {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for UseItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for UseTree {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Alias {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for UseTreeList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ExternCrateItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ArgList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for Path {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for PathSegment {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeArgList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for TypeArg {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for AssocTypeArg {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for LifetimeArg {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ConstArg {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MacroItems {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MacroStmts {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ExternItemList {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for ExternBlock {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MetaItem {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
 impl std::fmt::Display for MacroDef {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
diff --git a/crates/ra_syntax/src/ast/generated/tokens.rs b/crates/ra_syntax/src/ast/generated/tokens.rs
index f91befaac..abadd0b61 100644
--- a/crates/ra_syntax/src/ast/generated/tokens.rs
+++ b/crates/ra_syntax/src/ast/generated/tokens.rs
@@ -11,7 +11,7 @@ pub struct Whitespace {
     pub(crate) syntax: SyntaxToken,
 }
 impl std::fmt::Display for Whitespace {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(&self.syntax, f)
     }
 }
@@ -32,7 +32,7 @@ pub struct Comment {
     pub(crate) syntax: SyntaxToken,
 }
 impl std::fmt::Display for Comment {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(&self.syntax, f)
     }
 }
@@ -53,7 +53,7 @@ pub struct String {
     pub(crate) syntax: SyntaxToken,
 }
 impl std::fmt::Display for String {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(&self.syntax, f)
     }
 }
@@ -74,7 +74,7 @@ pub struct RawString {
     pub(crate) syntax: SyntaxToken,
 }
 impl std::fmt::Display for RawString {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(&self.syntax, f)
     }
 }
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index da0eb0926..192c610f1 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -75,6 +75,10 @@ pub fn record_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordF
     }
 }
 
+pub fn record_field_def(name: ast::NameRef, ty: ast::TypeRef) -> ast::RecordFieldDef {
+    ast_from_text(&format!("struct S {{ {}: {}, }}", name, ty))
+}
+
 pub fn block_expr(
     stmts: impl IntoIterator<Item = ast::Stmt>,
     tail_expr: Option<ast::Expr>,
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
index 3cd6d99c3..045f69133 100644
--- a/crates/ra_syntax/src/ast/tokens.rs
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -1,6 +1,9 @@
 //! There are many AstNodes, but only a few tokens, so we hand-write them here.
 
-use std::convert::{TryFrom, TryInto};
+use std::{
+    borrow::Cow,
+    convert::{TryFrom, TryInto},
+};
 
 use crate::{
     ast::{AstToken, Comment, RawString, String, Whitespace},
@@ -84,7 +87,7 @@ impl Whitespace {
 }
 
 pub struct QuoteOffsets {
-    pub quotes: [TextRange; 2],
+    pub quotes: (TextRange, TextRange),
     pub contents: TextRange,
 }
 
@@ -103,7 +106,7 @@ impl QuoteOffsets {
         let end = TextSize::of(literal);
 
         let res = QuoteOffsets {
-            quotes: [TextRange::new(start, left_quote), TextRange::new(right_quote, end)],
+            quotes: (TextRange::new(start, left_quote), TextRange::new(right_quote, end)),
             contents: TextRange::new(left_quote, right_quote),
         };
         Some(res)
@@ -116,17 +119,17 @@ pub trait HasQuotes: AstToken {
         let offsets = QuoteOffsets::new(text)?;
         let o = self.syntax().text_range().start();
         let offsets = QuoteOffsets {
-            quotes: [offsets.quotes[0] + o, offsets.quotes[1] + o],
+            quotes: (offsets.quotes.0 + o, offsets.quotes.1 + o),
             contents: offsets.contents + o,
         };
         Some(offsets)
     }
     fn open_quote_text_range(&self) -> Option<TextRange> {
-        self.quote_offsets().map(|it| it.quotes[0])
+        self.quote_offsets().map(|it| it.quotes.0)
     }
 
     fn close_quote_text_range(&self) -> Option<TextRange> {
-        self.quote_offsets().map(|it| it.quotes[1])
+        self.quote_offsets().map(|it| it.quotes.1)
     }
 
     fn text_range_between_quotes(&self) -> Option<TextRange> {
@@ -138,11 +141,11 @@ impl HasQuotes for String {}
 impl HasQuotes for RawString {}
 
 pub trait HasStringValue: HasQuotes {
-    fn value(&self) -> Option<std::string::String>;
+    fn value(&self) -> Option<Cow<'_, str>>;
 }
 
 impl HasStringValue for String {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
 
@@ -156,15 +159,17 @@ impl HasStringValue for String {
         if has_error {
             return None;
         }
-        Some(buf)
+        // FIXME: don't actually allocate for borrowed case
+        let res = if buf == text { Cow::Borrowed(text) } else { Cow::Owned(buf) };
+        Some(res)
     }
 }
 
 impl HasStringValue for RawString {
-    fn value(&self) -> Option<std::string::String> {
+    fn value(&self) -> Option<Cow<'_, str>> {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
-        Some(text.to_string())
+        Some(Cow::Borrowed(text))
     }
 }
 
@@ -335,16 +340,26 @@ pub trait HasFormatSpecifier: AstToken {
                             }
                             c if c == '_' || c.is_alphabetic() => {
                                 read_identifier(&mut chars, &mut callback);
-                                if chars.peek().and_then(|next| next.1.as_ref().ok()).copied()
-                                    != Some('$')
-                                {
-                                    continue;
-                                }
-                                skip_char_and_emit(
-                                    &mut chars,
-                                    FormatSpecifier::DollarSign,
-                                    &mut callback,
-                                );
+                                // can be either width (indicated by dollar sign, or type in which case
+                                // the next sign has to be `}`)
+                                let next =
+                                    chars.peek().and_then(|next| next.1.as_ref().ok()).copied();
+                                match next {
+                                    Some('$') => skip_char_and_emit(
+                                        &mut chars,
+                                        FormatSpecifier::DollarSign,
+                                        &mut callback,
+                                    ),
+                                    Some('}') => {
+                                        skip_char_and_emit(
+                                            &mut chars,
+                                            FormatSpecifier::Close,
+                                            &mut callback,
+                                        );
+                                        continue;
+                                    }
+                                    _ => continue,
+                                };
                             }
                             _ => {}
                         }
@@ -416,17 +431,11 @@ pub trait HasFormatSpecifier: AstToken {
                         }
                     }
 
-                    let mut cloned = chars.clone().take(2);
-                    let first = cloned.next().and_then(|next| next.1.as_ref().ok()).copied();
-                    let second = cloned.next().and_then(|next| next.1.as_ref().ok()).copied();
-                    if first != Some('}') {
-                        continue;
-                    }
-                    if second == Some('}') {
-                        // Escaped format end specifier, `}}`
+                    if let Some((_, Ok('}'))) = chars.peek() {
+                        skip_char_and_emit(&mut chars, FormatSpecifier::Close, &mut callback);
+                    } else {
                         continue;
                     }
-                    skip_char_and_emit(&mut chars, FormatSpecifier::Close, &mut callback);
                 }
                 _ => {
                     while let Some((_, Ok(next_char))) = chars.peek() {
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index bfc05e08b..a8f2454fd 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -83,13 +83,22 @@ pub trait DocCommentsOwner: AstNode {
         CommentIter { iter: self.syntax().children_with_tokens() }
     }
 
+    fn doc_comment_text(&self) -> Option<String> {
+        self.doc_comments().doc_comment_text()
+    }
+}
+
+impl CommentIter {
+    pub fn from_syntax_node(syntax_node: &ast::SyntaxNode) -> CommentIter {
+        CommentIter { iter: syntax_node.children_with_tokens() }
+    }
+
     /// Returns the textual content of a doc comment block as a single string.
     /// That is, strips leading `///` (+ optional 1 character of whitespace),
     /// trailing `*/`, trailing whitespace and then joins the lines.
-    fn doc_comment_text(&self) -> Option<String> {
+    pub fn doc_comment_text(self) -> Option<String> {
         let mut has_comments = false;
         let docs = self
-            .doc_comments()
             .filter(|comment| comment.kind().doc.is_some())
             .map(|comment| {
                 has_comments = true;
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index 61e686da5..9b7664576 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -51,7 +51,8 @@ pub use crate::{
     ptr::{AstPtr, SyntaxNodePtr},
     syntax_error::SyntaxError,
     syntax_node::{
-        Direction, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken, SyntaxTreeBuilder,
+        Direction, NodeOrToken, SyntaxElement, SyntaxElementChildren, SyntaxNode,
+        SyntaxNodeChildren, SyntaxToken, SyntaxTreeBuilder,
     },
 };
 pub use ra_parser::{SyntaxKind, T};
@@ -167,6 +168,41 @@ impl SourceFile {
     }
 }
 
+impl ast::Path {
+    /// Returns `text`, parsed as a path, but only if it has no errors.
+    pub fn parse(text: &str) -> Result<Self, ()> {
+        parsing::parse_text_fragment(text, ra_parser::FragmentKind::Path)
+    }
+}
+
+impl ast::Pat {
+    /// Returns `text`, parsed as a pattern, but only if it has no errors.
+    pub fn parse(text: &str) -> Result<Self, ()> {
+        parsing::parse_text_fragment(text, ra_parser::FragmentKind::Pattern)
+    }
+}
+
+impl ast::Expr {
+    /// Returns `text`, parsed as an expression, but only if it has no errors.
+    pub fn parse(text: &str) -> Result<Self, ()> {
+        parsing::parse_text_fragment(text, ra_parser::FragmentKind::Expr)
+    }
+}
+
+impl ast::ModuleItem {
+    /// Returns `text`, parsed as an item, but only if it has no errors.
+    pub fn parse(text: &str) -> Result<Self, ()> {
+        parsing::parse_text_fragment(text, ra_parser::FragmentKind::Item)
+    }
+}
+
+impl ast::TypeRef {
+    /// Returns `text`, parsed as an type reference, but only if it has no errors.
+    pub fn parse(text: &str) -> Result<Self, ()> {
+        parsing::parse_text_fragment(text, ra_parser::FragmentKind::Type)
+    }
+}
+
 /// Matches a `SyntaxNode` against an `ast` type.
 ///
 /// # Example:
diff --git a/crates/ra_syntax/src/parsing.rs b/crates/ra_syntax/src/parsing.rs
index e5eb80850..0ed3c20ef 100644
--- a/crates/ra_syntax/src/parsing.rs
+++ b/crates/ra_syntax/src/parsing.rs
@@ -6,13 +6,14 @@ mod text_token_source;
 mod text_tree_sink;
 mod reparsing;
 
-use crate::{syntax_node::GreenNode, SyntaxError};
+use crate::{syntax_node::GreenNode, AstNode, SyntaxError, SyntaxNode};
 use text_token_source::TextTokenSource;
 use text_tree_sink::TextTreeSink;
 
 pub use lexer::*;
 
 pub(crate) use self::reparsing::incremental_reparse;
+use ra_parser::SyntaxKind;
 
 pub(crate) fn parse_text(text: &str) -> (GreenNode, Vec<SyntaxError>) {
     let (tokens, lexer_errors) = tokenize(&text);
@@ -27,3 +28,32 @@ pub(crate) fn parse_text(text: &str) -> (GreenNode, Vec<SyntaxError>) {
 
     (tree, parser_errors)
 }
+
+/// Returns `text` parsed as a `T` provided there are no parse errors.
+pub(crate) fn parse_text_fragment<T: AstNode>(
+    text: &str,
+    fragment_kind: ra_parser::FragmentKind,
+) -> Result<T, ()> {
+    let (tokens, lexer_errors) = tokenize(&text);
+    if !lexer_errors.is_empty() {
+        return Err(());
+    }
+
+    let mut token_source = TextTokenSource::new(text, &tokens);
+    let mut tree_sink = TextTreeSink::new(text, &tokens);
+
+    // TextTreeSink assumes that there's at least some root node to which it can attach errors and
+    // tokens. We arbitrarily give it a SourceFile.
+    use ra_parser::TreeSink;
+    tree_sink.start_node(SyntaxKind::SOURCE_FILE);
+    ra_parser::parse_fragment(&mut token_source, &mut tree_sink, fragment_kind);
+    tree_sink.finish_node();
+
+    let (tree, parser_errors) = tree_sink.finish();
+    use ra_parser::TokenSource;
+    if !parser_errors.is_empty() || token_source.current().kind != SyntaxKind::EOF {
+        return Err(());
+    }
+
+    SyntaxNode::new_root(tree).first_child().and_then(T::cast).ok_or(())
+}
diff --git a/crates/ra_syntax/src/parsing/lexer.rs b/crates/ra_syntax/src/parsing/lexer.rs
index 1a5a6dc06..fa3be1016 100644
--- a/crates/ra_syntax/src/parsing/lexer.rs
+++ b/crates/ra_syntax/src/parsing/lexer.rs
@@ -1,6 +1,8 @@
 //! Lexer analyzes raw input string and produces lexemes (tokens).
 //! It is just a bridge to `rustc_lexer`.
 
+use rustc_lexer::{LiteralKind as LK, RawStrError};
+
 use std::convert::TryInto;
 
 use crate::{
@@ -180,8 +182,6 @@ fn rustc_token_kind_to_syntax_kind(
     return (syntax_kind, None);
 
     fn match_literal_kind(kind: &rustc_lexer::LiteralKind) -> (SyntaxKind, Option<&'static str>) {
-        use rustc_lexer::{LexRawStrError, LiteralKind as LK};
-
         #[rustfmt::skip]
         let syntax_kind = match *kind {
             LK::Int { empty_int: false, .. } => INT_NUMBER,
@@ -215,27 +215,27 @@ fn rustc_token_kind_to_syntax_kind(
                 return (BYTE_STRING, Some("Missing trailing `\"` symbol to terminate the byte string literal"))
             }
 
-            LK::RawStr(str) => match str.validate() {
-                Ok(_) => RAW_STRING,
-                Err(LexRawStrError::InvalidStarter) => return (RAW_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw string literal")),
-                Err(LexRawStrError::NoTerminator { expected, found, .. }) => if expected == found {
+            LK::RawStr { err, .. } => match err {
+                None => RAW_STRING,
+                Some(RawStrError::InvalidStarter { .. }) => return (RAW_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw string literal")),
+                Some(RawStrError::NoTerminator { expected, found, .. }) => if expected == found {
                     return (RAW_STRING, Some("Missing trailing `\"` to terminate the raw string literal"))
                 } else {
                     return (RAW_STRING, Some("Missing trailing `\"` with `#` symbols to terminate the raw string literal"))
 
                 },
-                Err(LexRawStrError::TooManyDelimiters { .. }) => return (RAW_STRING, Some("Too many `#` symbols: raw strings may be delimited by up to 65535 `#` symbols")),
+                Some(RawStrError::TooManyDelimiters { .. }) => return (RAW_STRING, Some("Too many `#` symbols: raw strings may be delimited by up to 65535 `#` symbols")),
             },
-            LK::RawByteStr(str) => match str.validate() {
-                Ok(_) => RAW_BYTE_STRING,
-                Err(LexRawStrError::InvalidStarter) => return (RAW_BYTE_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw byte string literal")),
-                Err(LexRawStrError::NoTerminator { expected, found, .. }) => if expected == found {
+            LK::RawByteStr { err, .. } => match err {
+                None => RAW_BYTE_STRING,
+                Some(RawStrError::InvalidStarter { .. }) => return (RAW_BYTE_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw byte string literal")),
+                Some(RawStrError::NoTerminator { expected, found, .. }) => if expected == found {
                     return (RAW_BYTE_STRING, Some("Missing trailing `\"` to terminate the raw byte string literal"))
                 } else {
                     return (RAW_BYTE_STRING, Some("Missing trailing `\"` with `#` symbols to terminate the raw byte string literal"))
 
                 },
-                Err(LexRawStrError::TooManyDelimiters { .. }) => return (RAW_BYTE_STRING, Some("Too many `#` symbols: raw byte strings may be delimited by up to 65535 `#` symbols")),
+                Some(RawStrError::TooManyDelimiters { .. }) => return (RAW_BYTE_STRING, Some("Too many `#` symbols: raw byte strings may be delimited by up to 65535 `#` symbols")),
             },
         };
 
diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index edbc190f8..ed5a42ea3 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -120,10 +120,7 @@ fn get_text_after_edit(element: SyntaxElement, edit: &Indel) -> String {
 }
 
 fn is_contextual_kw(text: &str) -> bool {
-    match text {
-        "auto" | "default" | "union" => true,
-        _ => false,
-    }
+    matches!(text, "auto" | "default" | "union")
 }
 
 fn find_reparsable_node(node: &SyntaxNode, range: TextRange) -> Option<(SyntaxNode, Reparser)> {
diff --git a/crates/ra_syntax/src/parsing/text_token_source.rs b/crates/ra_syntax/src/parsing/text_token_source.rs
index 7ddc2c2c3..97aa3e795 100644
--- a/crates/ra_syntax/src/parsing/text_token_source.rs
+++ b/crates/ra_syntax/src/parsing/text_token_source.rs
@@ -1,40 +1,35 @@
-//! FIXME: write short doc here
+//! See `TextTokenSource` docs.
 
-use ra_parser::Token as PToken;
 use ra_parser::TokenSource;
 
 use crate::{parsing::lexer::Token, SyntaxKind::EOF, TextRange, TextSize};
 
+/// Implementation of `ra_parser::TokenSource` that takes tokens from source code text.
 pub(crate) struct TextTokenSource<'t> {
     text: &'t str,
-    /// start position of each token(expect whitespace and comment)
+    /// token and its start position (non-whitespace/comment tokens)
     /// ```non-rust
     ///  struct Foo;
-    /// ^------^---
-    /// |      |  ^-
-    /// 0      7  10
+    ///  ^------^--^-
+    ///  |      |    \________
+    ///  |      \____         \
+    ///  |           \         |
+    ///  (struct, 0) (Foo, 7) (;, 10)
     /// ```
-    /// (token, start_offset): `[(struct, 0), (Foo, 7), (;, 10)]`
-    start_offsets: Vec<TextSize>,
-    /// non-whitespace/comment tokens
-    /// ```non-rust
-    /// struct Foo {}
-    /// ^^^^^^ ^^^ ^^
-    /// ```
-    /// tokens: `[struct, Foo, {, }]`
-    tokens: Vec<Token>,
+    /// `[(struct, 0), (Foo, 7), (;, 10)]`
+    token_offset_pairs: Vec<(Token, TextSize)>,
 
     /// Current token and position
-    curr: (PToken, usize),
+    curr: (ra_parser::Token, usize),
 }
 
 impl<'t> TokenSource for TextTokenSource<'t> {
-    fn current(&self) -> PToken {
+    fn current(&self) -> ra_parser::Token {
         self.curr.0
     }
 
-    fn lookahead_nth(&self, n: usize) -> PToken {
-        mk_token(self.curr.1 + n, &self.start_offsets, &self.tokens)
+    fn lookahead_nth(&self, n: usize) -> ra_parser::Token {
+        mk_token(self.curr.1 + n, &self.token_offset_pairs)
     }
 
     fn bump(&mut self) {
@@ -43,45 +38,47 @@ impl<'t> TokenSource for TextTokenSource<'t> {
         }
 
         let pos = self.curr.1 + 1;
-        self.curr = (mk_token(pos, &self.start_offsets, &self.tokens), pos);
+        self.curr = (mk_token(pos, &self.token_offset_pairs), pos);
     }
 
     fn is_keyword(&self, kw: &str) -> bool {
-        let pos = self.curr.1;
-        if pos >= self.tokens.len() {
-            return false;
-        }
-        let range = TextRange::at(self.start_offsets[pos], self.tokens[pos].len);
-        self.text[range] == *kw
+        self.token_offset_pairs
+            .get(self.curr.1)
+            .map(|(token, offset)| &self.text[TextRange::at(*offset, token.len)] == kw)
+            .unwrap_or(false)
     }
 }
 
-fn mk_token(pos: usize, start_offsets: &[TextSize], tokens: &[Token]) -> PToken {
-    let kind = tokens.get(pos).map(|t| t.kind).unwrap_or(EOF);
-    let is_jointed_to_next = if pos + 1 < start_offsets.len() {
-        start_offsets[pos] + tokens[pos].len == start_offsets[pos + 1]
-    } else {
-        false
+fn mk_token(pos: usize, token_offset_pairs: &[(Token, TextSize)]) -> ra_parser::Token {
+    let (kind, is_jointed_to_next) = match token_offset_pairs.get(pos) {
+        Some((token, offset)) => (
+            token.kind,
+            token_offset_pairs
+                .get(pos + 1)
+                .map(|(_, next_offset)| offset + token.len == *next_offset)
+                .unwrap_or(false),
+        ),
+        None => (EOF, false),
     };
-
-    PToken { kind, is_jointed_to_next }
+    ra_parser::Token { kind, is_jointed_to_next }
 }
 
 impl<'t> TextTokenSource<'t> {
     /// Generate input from tokens(expect comment and whitespace).
     pub fn new(text: &'t str, raw_tokens: &'t [Token]) -> TextTokenSource<'t> {
-        let mut tokens = Vec::new();
-        let mut start_offsets = Vec::new();
-        let mut len = 0.into();
-        for &token in raw_tokens.iter() {
-            if !token.kind.is_trivia() {
-                tokens.push(token);
-                start_offsets.push(len);
-            }
-            len += token.len;
-        }
+        let token_offset_pairs: Vec<_> = raw_tokens
+            .iter()
+            .filter_map({
+                let mut len = 0.into();
+                move |token| {
+                    let pair = if token.kind.is_trivia() { None } else { Some((*token, len)) };
+                    len += token.len;
+                    pair
+                }
+            })
+            .collect();
 
-        let first = mk_token(0, &start_offsets, &tokens);
-        TextTokenSource { text, start_offsets, tokens, curr: (first, 0) }
+        let first = mk_token(0, &token_offset_pairs);
+        TextTokenSource { text, token_offset_pairs, curr: (first, 0) }
     }
 }
diff --git a/crates/ra_syntax/src/parsing/text_tree_sink.rs b/crates/ra_syntax/src/parsing/text_tree_sink.rs
index 22aed1db1..c6b30a02a 100644
--- a/crates/ra_syntax/src/parsing/text_tree_sink.rs
+++ b/crates/ra_syntax/src/parsing/text_tree_sink.rs
@@ -160,7 +160,10 @@ fn n_attached_trivias<'a>(
                             if let Some((peek_kind, peek_text)) =
                                 trivias.peek().map(|(_, pair)| pair)
                             {
-                                if *peek_kind == COMMENT && peek_text.starts_with("///") {
+                                if *peek_kind == COMMENT
+                                    && peek_text.starts_with("///")
+                                    && !peek_text.starts_with("////")
+                                {
                                     continue;
                                 }
                             }
diff --git a/crates/ra_syntax/src/syntax_node.rs b/crates/ra_syntax/src/syntax_node.rs
index e566af7e8..9650b8781 100644
--- a/crates/ra_syntax/src/syntax_node.rs
+++ b/crates/ra_syntax/src/syntax_node.rs
@@ -48,11 +48,11 @@ impl SyntaxTreeBuilder {
 
     pub fn finish(self) -> Parse<SyntaxNode> {
         let (green, errors) = self.finish_raw();
-        let node = SyntaxNode::new_root(green);
         if cfg!(debug_assertions) {
+            let node = SyntaxNode::new_root(green.clone());
             crate::validation::validate_block_structure(&node);
         }
-        Parse::new(node.green().clone(), errors)
+        Parse::new(green, errors)
     }
 
     pub fn token(&mut self, kind: SyntaxKind, text: SmolStr) {
diff --git a/crates/ra_syntax/src/tests.rs b/crates/ra_syntax/src/tests.rs
index aee57db62..8447dcad7 100644
--- a/crates/ra_syntax/src/tests.rs
+++ b/crates/ra_syntax/src/tests.rs
@@ -1,9 +1,12 @@
 use std::{
     fmt::Write,
-    path::{Component, Path, PathBuf},
+    fs,
+    path::{Path, PathBuf},
 };
 
-use test_utils::{collect_rust_files, dir_tests, project_dir, read_text};
+use expect::expect_file;
+use rayon::prelude::*;
+use test_utils::project_dir;
 
 use crate::{fuzz, tokenize, SourceFile, SyntaxError, TextRange, TextSize, Token};
 
@@ -55,6 +58,51 @@ fn parser_tests() {
 }
 
 #[test]
+fn expr_parser_tests() {
+    fragment_parser_dir_test(
+        &["parser/fragments/expr/ok"],
+        &["parser/fragments/expr/err"],
+        crate::ast::Expr::parse,
+    );
+}
+
+#[test]
+fn path_parser_tests() {
+    fragment_parser_dir_test(
+        &["parser/fragments/path/ok"],
+        &["parser/fragments/path/err"],
+        crate::ast::Path::parse,
+    );
+}
+
+#[test]
+fn pattern_parser_tests() {
+    fragment_parser_dir_test(
+        &["parser/fragments/pattern/ok"],
+        &["parser/fragments/pattern/err"],
+        crate::ast::Pat::parse,
+    );
+}
+
+#[test]
+fn item_parser_tests() {
+    fragment_parser_dir_test(
+        &["parser/fragments/item/ok"],
+        &["parser/fragments/item/err"],
+        crate::ast::ModuleItem::parse,
+    );
+}
+
+#[test]
+fn type_parser_tests() {
+    fragment_parser_dir_test(
+        &["parser/fragments/type/ok"],
+        &["parser/fragments/type/err"],
+        crate::ast::TypeRef::parse,
+    );
+}
+
+#[test]
 fn parser_fuzz_tests() {
     for (_, text) in collect_rust_files(&test_data_dir(), &["parser/fuzz-failures"]) {
         fuzz::check_parser(&text)
@@ -74,33 +122,43 @@ fn reparse_fuzz_tests() {
 /// FIXME: Use this as a benchmark
 #[test]
 fn self_hosting_parsing() {
-    use std::ffi::OsStr;
     let dir = project_dir().join("crates");
-    let mut count = 0;
-    for entry in walkdir::WalkDir::new(dir)
+    let files = walkdir::WalkDir::new(dir)
         .into_iter()
         .filter_entry(|entry| {
-            !entry.path().components().any(|component| {
-                // Get all files which are not in the crates/ra_syntax/test_data folder
-                component == Component::Normal(OsStr::new("test_data"))
-            })
+            // Get all files which are not in the crates/ra_syntax/test_data folder
+            !entry.path().components().any(|component| component.as_os_str() == "test_data")
         })
         .map(|e| e.unwrap())
         .filter(|entry| {
             // Get all `.rs ` files
-            !entry.path().is_dir() && (entry.path().extension() == Some(OsStr::new("rs")))
+            !entry.path().is_dir() && (entry.path().extension().unwrap_or_default() == "rs")
         })
-    {
-        count += 1;
-        let text = read_text(entry.path());
-        if let Err(errors) = SourceFile::parse(&text).ok() {
-            panic!("Parsing errors:\n{:?}\n{}\n", errors, entry.path().display());
-        }
-    }
+        .map(|entry| entry.into_path())
+        .collect::<Vec<_>>();
     assert!(
-        count > 30,
+        files.len() > 100,
         "self_hosting_parsing found too few files - is it running in the right directory?"
-    )
+    );
+
+    let errors = files
+        .into_par_iter()
+        .filter_map(|file| {
+            let text = read_text(&file);
+            match SourceFile::parse(&text).ok() {
+                Ok(_) => None,
+                Err(err) => Some((file, err)),
+            }
+        })
+        .collect::<Vec<_>>();
+
+    if !errors.is_empty() {
+        let errors = errors
+            .into_iter()
+            .map(|(path, err)| format!("{}: {:?}\n", path.display(), err))
+            .collect::<String>();
+        panic!("Parsing errors:\n{}\n", errors);
+    }
 }
 
 fn test_data_dir() -> PathBuf {
@@ -134,3 +192,89 @@ fn dump_tokens_and_errors(tokens: &[Token], errors: &[SyntaxError], text: &str)
     }
     acc
 }
+
+fn fragment_parser_dir_test<T, F>(ok_paths: &[&str], err_paths: &[&str], f: F)
+where
+    T: crate::AstNode,
+    F: Fn(&str) -> Result<T, ()>,
+{
+    dir_tests(&test_data_dir(), ok_paths, "rast", |text, path| {
+        if let Ok(node) = f(text) {
+            format!("{:#?}", crate::ast::AstNode::syntax(&node))
+        } else {
+            panic!("Failed to parse '{:?}'", path);
+        }
+    });
+    dir_tests(&test_data_dir(), err_paths, "rast", |text, path| {
+        if let Ok(_) = f(text) {
+            panic!("'{:?}' successfully parsed when it should have errored", path);
+        } else {
+            "ERROR\n".to_owned()
+        }
+    });
+}
+
+/// Calls callback `f` with input code and file paths for each `.rs` file in `test_data_dir`
+/// subdirectories defined by `paths`.
+///
+/// If the content of the matching output file differs from the output of `f()`
+/// the test will fail.
+///
+/// If there is no matching output file it will be created and filled with the
+/// output of `f()`, but the test will fail.
+fn dir_tests<F>(test_data_dir: &Path, paths: &[&str], outfile_extension: &str, f: F)
+where
+    F: Fn(&str, &Path) -> String,
+{
+    for (path, input_code) in collect_rust_files(test_data_dir, paths) {
+        let actual = f(&input_code, &path);
+        let path = path.with_extension(outfile_extension);
+        expect_file![path].assert_eq(&actual)
+    }
+}
+
+/// Collects all `.rs` files from `dir` subdirectories defined by `paths`.
+fn collect_rust_files(root_dir: &Path, paths: &[&str]) -> Vec<(PathBuf, String)> {
+    paths
+        .iter()
+        .flat_map(|path| {
+            let path = root_dir.to_owned().join(path);
+            rust_files_in_dir(&path).into_iter()
+        })
+        .map(|path| {
+            let text = read_text(&path);
+            (path, text)
+        })
+        .collect()
+}
+
+/// Collects paths to all `.rs` files from `dir` in a sorted `Vec<PathBuf>`.
+fn rust_files_in_dir(dir: &Path) -> Vec<PathBuf> {
+    let mut acc = Vec::new();
+    for file in fs::read_dir(&dir).unwrap() {
+        let file = file.unwrap();
+        let path = file.path();
+        if path.extension().unwrap_or_default() == "rs" {
+            acc.push(path);
+        }
+    }
+    acc.sort();
+    acc
+}
+
+/// Read file and normalize newlines.
+///
+/// `rustc` seems to always normalize `\r\n` newlines to `\n`:
+///
+/// ```
+/// let s = "
+/// ";
+/// assert_eq!(s.as_bytes(), &[10]);
+/// ```
+///
+/// so this should always be correct.
+fn read_text(path: &Path) -> String {
+    fs::read_to_string(path)
+        .unwrap_or_else(|_| panic!("File at {:?} should be valid", path))
+        .replace("\r\n", "\n")
+}