16 files changed, 238 insertions, 150 deletions

diff --git a/crates/ra_assists/src/assists/add_new.rs b/crates/ra_assists/src/assists/add_new.rs
index d340cac8f..b2f946fac 100644
--- a/crates/ra_assists/src/assists/add_new.rs
+++ b/crates/ra_assists/src/assists/add_new.rs
@@ -139,43 +139,40 @@ fn find_struct_impl(
 
     let struct_ty = {
         let src = InFile { file_id: ctx.frange.file_id.into(), value: strukt.clone() };
-        hir::Struct::from_source(db, src).unwrap().ty(db)
+        hir::Struct::from_source(db, src)?.ty(db)
     };
 
-    let mut found_new_fn = false;
-
-    let block = module.descendants().filter_map(ast::ImplBlock::cast).find(|impl_blk| {
-        if found_new_fn {
-            return false;
-        }
-
+    let block = module.descendants().filter_map(ast::ImplBlock::cast).find_map(|impl_blk| {
         let src = InFile { file_id: ctx.frange.file_id.into(), value: impl_blk.clone() };
-        let blk = hir::ImplBlock::from_source(db, src).unwrap();
+        let blk = hir::ImplBlock::from_source(db, src)?;
 
         let same_ty = blk.target_ty(db) == struct_ty;
         let not_trait_impl = blk.target_trait(db).is_none();
 
         if !(same_ty && not_trait_impl) {
-            return false;
+            None
+        } else {
+            Some(impl_blk)
         }
-
-        found_new_fn = has_new_fn(impl_blk);
-        true
     });
 
-    if found_new_fn {
-        None
-    } else {
-        Some(block)
+    if let Some(ref impl_blk) = block {
+        if has_new_fn(impl_blk) {
+            return None;
+        }
     }
+
+    Some(block)
 }
 
 fn has_new_fn(imp: &ast::ImplBlock) -> bool {
     if let Some(il) = imp.item_list() {
         for item in il.impl_items() {
             if let ast::ImplItem::FnDef(f) = item {
-                if f.name().unwrap().text().eq_ignore_ascii_case("new") {
-                    return true;
+                if let Some(name) = f.name() {
+                    if name.text().eq_ignore_ascii_case("new") {
+                        return true;
+                    }
                 }
             }
         }
diff --git a/crates/ra_hir_def/src/path.rs b/crates/ra_hir_def/src/path.rs
index ec9d13e82..50f0cad94 100644
--- a/crates/ra_hir_def/src/path.rs
+++ b/crates/ra_hir_def/src/path.rs
@@ -342,6 +342,14 @@ pub mod known {
         )
     }
 
+    pub fn std_ops_neg() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::NEG_TYPE])
+    }
+
+    pub fn std_ops_not() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::NOT_TYPE])
+    }
+
     pub fn std_result_result() -> Path {
         Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::RESULT, name::RESULT_TYPE])
     }
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index 4f2f702c0..9e68dd98d 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -152,6 +152,8 @@ pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeInclusive")
 pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeToInclusive");
 pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(b"RangeTo");
 pub const RANGE_TYPE: Name = Name::new_inline_ascii(b"Range");
+pub const NEG_TYPE: Name = Name::new_inline_ascii(b"Neg");
+pub const NOT_TYPE: Name = Name::new_inline_ascii(b"Not");
 
 // Builtin Macros
 pub const FILE_MACRO: Name = Name::new_inline_ascii(b"file");
diff --git a/crates/ra_hir_expand/src/quote.rs b/crates/ra_hir_expand/src/quote.rs
index 4f698ff13..aa8a5f23f 100644
--- a/crates/ra_hir_expand/src/quote.rs
+++ b/crates/ra_hir_expand/src/quote.rs
@@ -16,7 +16,7 @@ macro_rules! __quote {
         {
             let children = $crate::__quote!($($tt)*);
             let subtree = tt::Subtree {
-                delimiter: tt::Delimiter::$delim,
+                delimiter: Some(tt::Delimiter::$delim),
                 token_trees: $crate::quote::IntoTt::to_tokens(children),
             };
             subtree
@@ -124,7 +124,7 @@ pub(crate) trait IntoTt {
 
 impl IntoTt for Vec<tt::TokenTree> {
     fn to_subtree(self) -> tt::Subtree {
-        tt::Subtree { delimiter: tt::Delimiter::None, token_trees: self }
+        tt::Subtree { delimiter: None, token_trees: self }
     }
 
     fn to_tokens(self) -> Vec<tt::TokenTree> {
@@ -254,7 +254,8 @@ mod tests {
         let fields =
             fields.iter().map(|it| quote!(#it: self.#it.clone(), ).token_trees.clone()).flatten();
 
-        let list = tt::Subtree { delimiter: tt::Delimiter::Brace, token_trees: fields.collect() };
+        let list =
+            tt::Subtree { delimiter: Some(tt::Delimiter::Brace), token_trees: fields.collect() };
 
         let quoted = quote! {
             impl Clone for #struct_name {
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index d16f1eb46..a1201b3e4 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -36,8 +36,8 @@ use ra_prof::profile;
 use super::{
     primitive::{FloatTy, IntTy},
     traits::{Guidance, Obligation, ProjectionPredicate, Solution},
-    ApplicationTy, InEnvironment, ProjectionTy, TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk,
-    Uncertain,
+    ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor,
+    TypeWalk, Uncertain,
 };
 use crate::{db::HirDatabase, infer::diagnostics::InferenceDiagnostic};
 
@@ -338,6 +338,24 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         self.table.resolve_ty_shallow(ty)
     }
 
+    fn resolve_associated_type(&mut self, inner_ty: Ty, assoc_ty: Option<TypeAliasId>) -> Ty {
+        match assoc_ty {
+            Some(res_assoc_ty) => {
+                let ty = self.table.new_type_var();
+                let projection = ProjectionPredicate {
+                    ty: ty.clone(),
+                    projection_ty: ProjectionTy {
+                        associated_ty: res_assoc_ty,
+                        parameters: Substs::single(inner_ty),
+                    },
+                };
+                self.obligations.push(Obligation::Projection(projection));
+                self.resolve_ty_as_possible(ty)
+            }
+            None => Ty::Unknown,
+        }
+    }
+
     /// Recurses through the given type, normalizing associated types mentioned
     /// in it by replacing them by type variables and registering obligations to
     /// resolve later. This should be done once for every type we get from some
@@ -415,6 +433,18 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         self.db.trait_data(trait_).associated_type_by_name(&name::OK_TYPE)
     }
 
+    fn resolve_ops_neg_output(&self) -> Option<TypeAliasId> {
+        let path = known::std_ops_neg();
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name::OUTPUT_TYPE)
+    }
+
+    fn resolve_ops_not_output(&self) -> Option<TypeAliasId> {
+        let path = known::std_ops_not();
+        let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
+        self.db.trait_data(trait_).associated_type_by_name(&name::OUTPUT_TYPE)
+    }
+
     fn resolve_future_future_output(&self) -> Option<TypeAliasId> {
         let path = known::std_future_future();
         let trait_ = self.resolver.resolve_known_trait(self.db, &path)?;
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 2c296987c..f8c00a7b4 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -19,8 +19,8 @@ use crate::{
     method_resolution, op,
     traits::InEnvironment,
     utils::{generics, variant_data, Generics},
-    CallableDef, InferTy, IntTy, Mutability, Obligation, ProjectionPredicate, ProjectionTy, Substs,
-    TraitRef, Ty, TypeCtor, TypeWalk, Uncertain,
+    ApplicationTy, CallableDef, InferTy, IntTy, Mutability, Obligation, Substs, TraitRef, Ty,
+    TypeCtor, TypeWalk, Uncertain,
 };
 
 use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
@@ -95,21 +95,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::For { iterable, body, pat } => {
                 let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
 
-                let pat_ty = match self.resolve_into_iter_item() {
-                    Some(into_iter_item_alias) => {
-                        let pat_ty = self.table.new_type_var();
-                        let projection = ProjectionPredicate {
-                            ty: pat_ty.clone(),
-                            projection_ty: ProjectionTy {
-                                associated_ty: into_iter_item_alias,
-                                parameters: Substs::single(iterable_ty),
-                            },
-                        };
-                        self.obligations.push(Obligation::Projection(projection));
-                        self.resolve_ty_as_possible(pat_ty)
-                    }
-                    None => Ty::Unknown,
-                };
+                let pat_ty =
+                    self.resolve_associated_type(iterable_ty, self.resolve_into_iter_item());
 
                 self.infer_pat(*pat, &pat_ty, BindingMode::default());
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
@@ -284,40 +271,13 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             }
             Expr::Await { expr } => {
                 let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
-                let ty = match self.resolve_future_future_output() {
-                    Some(future_future_output_alias) => {
-                        let ty = self.table.new_type_var();
-                        let projection = ProjectionPredicate {
-                            ty: ty.clone(),
-                            projection_ty: ProjectionTy {
-                                associated_ty: future_future_output_alias,
-                                parameters: Substs::single(inner_ty),
-                            },
-                        };
-                        self.obligations.push(Obligation::Projection(projection));
-                        self.resolve_ty_as_possible(ty)
-                    }
-                    None => Ty::Unknown,
-                };
+                let ty =
+                    self.resolve_associated_type(inner_ty, self.resolve_future_future_output());
                 ty
             }
             Expr::Try { expr } => {
                 let inner_ty = self.infer_expr_inner(*expr, &Expectation::none());
-                let ty = match self.resolve_ops_try_ok() {
-                    Some(ops_try_ok_alias) => {
-                        let ty = self.table.new_type_var();
-                        let projection = ProjectionPredicate {
-                            ty: ty.clone(),
-                            projection_ty: ProjectionTy {
-                                associated_ty: ops_try_ok_alias,
-                                parameters: Substs::single(inner_ty),
-                            },
-                        };
-                        self.obligations.push(Obligation::Projection(projection));
-                        self.resolve_ty_as_possible(ty)
-                    }
-                    None => Ty::Unknown,
-                };
+                let ty = self.resolve_associated_type(inner_ty, self.resolve_ops_try_ok());
                 ty
             }
             Expr::Cast { expr, type_ref } => {
@@ -372,31 +332,36 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     },
                     UnaryOp::Neg => {
                         match &inner_ty {
-                            Ty::Apply(a_ty) => match a_ty.ctor {
-                                TypeCtor::Int(Uncertain::Unknown)
-                                | TypeCtor::Int(Uncertain::Known(IntTy {
-                                    signedness: Signedness::Signed,
-                                    ..
-                                }))
-                                | TypeCtor::Float(..) => inner_ty,
-                                _ => Ty::Unknown,
-                            },
-                            Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => {
-                                inner_ty
-                            }
-                            // FIXME: resolve ops::Neg trait
-                            _ => Ty::Unknown,
+                            // Fast path for builtins
+                            Ty::Apply(ApplicationTy {
+                                ctor:
+                                    TypeCtor::Int(Uncertain::Known(IntTy {
+                                        signedness: Signedness::Signed,
+                                        ..
+                                    })),
+                                ..
+                            })
+                            | Ty::Apply(ApplicationTy {
+                                ctor: TypeCtor::Int(Uncertain::Unknown),
+                                ..
+                            })
+                            | Ty::Apply(ApplicationTy { ctor: TypeCtor::Float(_), .. })
+                            | Ty::Infer(InferTy::IntVar(..))
+                            | Ty::Infer(InferTy::FloatVar(..)) => inner_ty,
+                            // Otherwise we resolve via the std::ops::Neg trait
+                            _ => self
+                                .resolve_associated_type(inner_ty, self.resolve_ops_neg_output()),
                         }
                     }
                     UnaryOp::Not => {
                         match &inner_ty {
-                            Ty::Apply(a_ty) => match a_ty.ctor {
-                                TypeCtor::Bool | TypeCtor::Int(_) => inner_ty,
-                                _ => Ty::Unknown,
-                            },
-                            Ty::Infer(InferTy::IntVar(..)) => inner_ty,
-                            // FIXME: resolve ops::Not trait for inner_ty
-                            _ => Ty::Unknown,
+                            // Fast path for builtins
+                            Ty::Apply(ApplicationTy { ctor: TypeCtor::Bool, .. })
+                            | Ty::Apply(ApplicationTy { ctor: TypeCtor::Int(_), .. })
+                            | Ty::Infer(InferTy::IntVar(..)) => inner_ty,
+                            // Otherwise we resolve via the std::ops::Not trait
+                            _ => self
+                                .resolve_associated_type(inner_ty, self.resolve_ops_not_output()),
                         }
                     }
                 }
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 93c5f9a15..6139adb72 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -116,6 +116,70 @@ mod collections {
 }
 
 #[test]
+fn infer_ops_neg() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+struct Bar;
+struct Foo;
+
+impl std::ops::Neg for Bar {
+    type Output = Foo;
+}
+
+fn test() {
+    let a = Bar;
+    let b = -a;
+    b<|>;
+}
+
+//- /std.rs crate:std
+
+#[prelude_import] use ops::*;
+mod ops {
+    pub trait Neg {
+        type Output;
+    }
+}
+"#,
+    );
+    assert_eq!("Foo", type_at_pos(&db, pos));
+}
+
+#[test]
+fn infer_ops_not() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs crate:main deps:std
+
+struct Bar;
+struct Foo;
+
+impl std::ops::Not for Bar {
+    type Output = Foo;
+}
+
+fn test() {
+    let a = Bar;
+    let b = !a;
+    b<|>;
+}
+
+//- /std.rs crate:std
+
+#[prelude_import] use ops::*;
+mod ops {
+    pub trait Not {
+        type Output;
+    }
+}
+"#,
+    );
+    assert_eq!("Foo", type_at_pos(&db, pos));
+}
+
+#[test]
 fn infer_from_bound_1() {
     assert_snapshot!(
         infer(r#"
diff --git a/crates/ra_ide/src/expand.rs b/crates/ra_ide/src/expand.rs
index 216d5cfec..661628ae4 100644
--- a/crates/ra_ide/src/expand.rs
+++ b/crates/ra_ide/src/expand.rs
@@ -3,7 +3,7 @@ use std::iter::successors;
 
 use hir::InFile;
 use ra_db::FileId;
-use ra_syntax::{ast, AstNode, SyntaxNode, SyntaxToken};
+use ra_syntax::{ast, AstNode, SyntaxNode, SyntaxToken, TextRange};
 
 use crate::{db::RootDatabase, FileRange};
 
@@ -17,26 +17,45 @@ pub(crate) fn original_range(db: &RootDatabase, node: InFile<&SyntaxNode>) -> Fi
         }
         Some(it) => it,
     };
-    // FIXME: the following completely wrong.
-    //
-    // *First*, we should try to map first and last tokens of node, and, if that
-    // fails, return the range of the overall macro expansions.
-    //
-    // *Second*, we should handle recurside macro expansions
-
-    let token = node
-        .value
-        .descendants_with_tokens()
-        .filter_map(|it| it.into_token())
-        .find_map(|it| expansion.map_token_up(node.with_value(&it)));
-
-    match token {
-        Some(it) => {
-            FileRange { file_id: it.file_id.original_file(db), range: it.value.text_range() }
+    // FIXME: We should handle recurside macro expansions
+
+    let range = node.value.descendants_with_tokens().find_map(|it| {
+        match it.as_token() {
+            // FIXME: Remove this branch after all `tt::TokenTree`s have a proper `TokenId`,
+            // and return the range of the overall macro expansions if mapping first and last tokens fails.
+            Some(token) => {
+                let token = expansion.map_token_up(node.with_value(&token))?;
+                Some(token.with_value(token.value.text_range()))
+            }
+            None => {
+                // Try to map first and last tokens of node, and, if success, return the union range of mapped tokens
+                let n = it.into_node()?;
+                let first = expansion.map_token_up(node.with_value(&n.first_token()?))?;
+                let last = expansion.map_token_up(node.with_value(&n.last_token()?))?;
+
+                // FIXME: Is is possible ?
+                if first.file_id != last.file_id {
+                    return None;
+                }
+
+                // FIXME: Add union method in TextRange
+                let range = union_range(first.value.text_range(), last.value.text_range());
+                Some(first.with_value(range))
+            }
         }
+    });
+
+    return match range {
+        Some(it) => FileRange { file_id: it.file_id.original_file(db), range: it.value },
         None => {
             FileRange { file_id: node.file_id.original_file(db), range: node.value.text_range() }
         }
+    };
+
+    fn union_range(a: TextRange, b: TextRange) -> TextRange {
+        let start = a.start().min(b.start());
+        let end = a.end().max(b.end());
+        TextRange::from_to(start, end)
     }
 }
 
diff --git a/crates/ra_lsp_server/src/conv.rs b/crates/ra_lsp_server/src/conv.rs
index b13093cfe..5561f6270 100644
--- a/crates/ra_lsp_server/src/conv.rs
+++ b/crates/ra_lsp_server/src/conv.rs
@@ -130,6 +130,11 @@ impl ConvWith<(&LineIndex, LineEndings)> for CompletionItem {
             deprecated: Some(self.deprecated()),
             ..Default::default()
         };
+
+        if self.deprecated() {
+            res.tags = Some(vec![lsp_types::CompletionItemTag::Deprecated])
+        }
+
         res.insert_text_format = Some(match self.insert_text_format() {
             InsertTextFormat::Snippet => lsp_types::InsertTextFormat::Snippet,
             InsertTextFormat::PlainText => lsp_types::InsertTextFormat::PlainText,
diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index bbddebe67..0d2d43bef 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -159,14 +159,14 @@ impl Rule {
             .expect_subtree()
             .map_err(|()| ParseError::Expected("expected subtree".to_string()))?
             .clone();
-        lhs.delimiter = tt::Delimiter::None;
+        lhs.delimiter = None;
         src.expect_char('=').map_err(|()| ParseError::Expected("expected `=`".to_string()))?;
         src.expect_char('>').map_err(|()| ParseError::Expected("expected `>`".to_string()))?;
         let mut rhs = src
             .expect_subtree()
             .map_err(|()| ParseError::Expected("expected subtree".to_string()))?
             .clone();
-        rhs.delimiter = tt::Delimiter::None;
+        rhs.delimiter = None;
         Ok(crate::Rule { lhs, rhs })
     }
 }
diff --git a/crates/ra_mbe/src/mbe_expander/matcher.rs b/crates/ra_mbe/src/mbe_expander/matcher.rs
index 33b9d483d..3f5136478 100644
--- a/crates/ra_mbe/src/mbe_expander/matcher.rs
+++ b/crates/ra_mbe/src/mbe_expander/matcher.rs
@@ -16,7 +16,7 @@ impl Bindings {
     fn push_optional(&mut self, name: &SmolStr) {
         // FIXME: Do we have a better way to represent an empty token ?
         // Insert an empty subtree for empty token
-        let tt = tt::Subtree { delimiter: tt::Delimiter::None, token_trees: vec![] }.into();
+        let tt = tt::Subtree::default().into();
         self.inner.insert(name.clone(), Binding::Fragment(Fragment::Tokens(tt)));
     }
 
@@ -65,7 +65,7 @@ macro_rules! bail {
 }
 
 pub(super) fn match_(pattern: &tt::Subtree, src: &tt::Subtree) -> Result<Bindings, ExpandError> {
-    assert!(pattern.delimiter == tt::Delimiter::None);
+    assert!(pattern.delimiter == None);
 
     let mut res = Bindings::default();
     let mut src = TtIter::new(src);
@@ -210,7 +210,7 @@ impl<'a> TtIter<'a> {
             0 => Err(()),
             1 => Ok(res[0].clone()),
             _ => Ok(tt::TokenTree::Subtree(tt::Subtree {
-                delimiter: tt::Delimiter::None,
+                delimiter: None,
                 token_trees: res.into_iter().cloned().collect(),
             })),
         }
diff --git a/crates/ra_mbe/src/mbe_expander/transcriber.rs b/crates/ra_mbe/src/mbe_expander/transcriber.rs
index ed094d5bb..f7636db11 100644
--- a/crates/ra_mbe/src/mbe_expander/transcriber.rs
+++ b/crates/ra_mbe/src/mbe_expander/transcriber.rs
@@ -50,7 +50,7 @@ pub(super) fn transcribe(
     template: &tt::Subtree,
     bindings: &Bindings,
 ) -> Result<tt::Subtree, ExpandError> {
-    assert!(template.delimiter == tt::Delimiter::None);
+    assert!(template.delimiter == None);
     let mut ctx = ExpandCtx { bindings: &bindings, nesting: Vec::new(), var_expanded: false };
     expand_subtree(&mut ctx, template)
 }
@@ -106,7 +106,7 @@ fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> Result<Fragment, ExpandError>
         // ```
         // We just treat it a normal tokens
         let tt = tt::Subtree {
-            delimiter: tt::Delimiter::None,
+            delimiter: None,
             token_trees: vec![
                 tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone }).into(),
                 tt::Leaf::from(tt::Ident { text: v.clone(), id: tt::TokenId::unspecified() })
@@ -147,7 +147,7 @@ fn expand_repeat(
     ctx.var_expanded = false;
 
     while let Ok(mut t) = expand_subtree(ctx, template) {
-        t.delimiter = tt::Delimiter::None;
+        t.delimiter = None;
         // if no var expanded in the child, we count it as a fail
         if !ctx.var_expanded {
             break;
@@ -212,7 +212,7 @@ fn expand_repeat(
 
     // Check if it is a single token subtree without any delimiter
     // e.g {Delimiter:None> ['>'] /Delimiter:None>}
-    let tt = tt::Subtree { delimiter: tt::Delimiter::None, token_trees: buf }.into();
+    let tt = tt::Subtree { delimiter: None, token_trees: buf }.into();
     Ok(Fragment::Tokens(tt))
 }
 
@@ -225,7 +225,7 @@ fn push_fragment(buf: &mut Vec<tt::TokenTree>, fragment: Fragment) {
 
 fn push_subtree(buf: &mut Vec<tt::TokenTree>, tt: tt::Subtree) {
     match tt.delimiter {
-        tt::Delimiter::None => buf.extend(tt.token_trees),
+        None => buf.extend(tt.token_trees),
         _ => buf.push(tt.into()),
     }
 }
diff --git a/crates/ra_mbe/src/subtree_source.rs b/crates/ra_mbe/src/subtree_source.rs
index 7ef45f6dc..061e9f20b 100644
--- a/crates/ra_mbe/src/subtree_source.rs
+++ b/crates/ra_mbe/src/subtree_source.rs
@@ -114,12 +114,12 @@ impl<'a> TokenSource for SubtreeTokenSource<'a> {
     }
 }
 
-fn convert_delim(d: tt::Delimiter, closing: bool) -> TtToken {
+fn convert_delim(d: Option<tt::Delimiter>, closing: bool) -> TtToken {
     let (kinds, texts) = match d {
-        tt::Delimiter::Parenthesis => ([T!['('], T![')']], "()"),
-        tt::Delimiter::Brace => ([T!['{'], T!['}']], "{}"),
-        tt::Delimiter::Bracket => ([T!['['], T![']']], "[]"),
-        tt::Delimiter::None => ([L_DOLLAR, R_DOLLAR], ""),
+        Some(tt::Delimiter::Parenthesis) => ([T!['('], T![')']], "()"),
+        Some(tt::Delimiter::Brace) => ([T!['{'], T!['}']], "{}"),
+        Some(tt::Delimiter::Bracket) => ([T!['['], T![']']], "[]"),
+        None => ([L_DOLLAR, R_DOLLAR], ""),
     };
 
     let idx = closing as usize;
diff --git a/crates/ra_mbe/src/syntax_bridge.rs b/crates/ra_mbe/src/syntax_bridge.rs
index 66c1f0337..b8e2cfc1d 100644
--- a/crates/ra_mbe/src/syntax_bridge.rs
+++ b/crates/ra_mbe/src/syntax_bridge.rs
@@ -51,7 +51,7 @@ pub fn token_tree_to_syntax_node(
 ) -> Result<(Parse<SyntaxNode>, TokenMap), ExpandError> {
     let tmp;
     let tokens = match tt {
-        tt::Subtree { delimiter: tt::Delimiter::None, token_trees } => token_trees.as_slice(),
+        tt::Subtree { delimiter: None, token_trees } => token_trees.as_slice(),
         _ => {
             tmp = [tt.clone().into()];
             &tmp[..]
@@ -121,7 +121,7 @@ fn convert_doc_comment(token: &ra_syntax::SyntaxToken) -> Option<Vec<tt::TokenTr
         token_trees.push(mk_punct('!'));
     }
     token_trees.push(tt::TokenTree::from(tt::Subtree {
-        delimiter: tt::Delimiter::Bracket,
+        delimiter: Some(tt::Delimiter::Bracket),
         token_trees: meta_tkns,
     }));
 
@@ -156,7 +156,7 @@ impl Convertor {
     fn go(&mut self, tt: &SyntaxNode) -> Option<tt::Subtree> {
         // This tree is empty
         if tt.first_child_or_token().is_none() {
-            return Some(tt::Subtree { token_trees: vec![], delimiter: tt::Delimiter::None });
+            return Some(tt::Subtree { token_trees: vec![], delimiter: None });
         }
 
         let first_child = tt.first_child_or_token()?;
@@ -173,7 +173,7 @@ impl Convertor {
         .last()
         .unwrap();
         if first_child.kind().is_trivia() {
-            return Some(tt::Subtree { token_trees: vec![], delimiter: tt::Delimiter::None });
+            return Some(tt::Subtree { token_trees: vec![], delimiter: None });
         }
 
         let last_child = successors(Some(last_child), |it| {
@@ -187,10 +187,10 @@ impl Convertor {
         .unwrap();
 
         let (delimiter, skip_first) = match (first_child.kind(), last_child.kind()) {
-            (T!['('], T![')']) => (tt::Delimiter::Parenthesis, true),
-            (T!['{'], T!['}']) => (tt::Delimiter::Brace, true),
-            (T!['['], T![']']) => (tt::Delimiter::Bracket, true),
-            _ => (tt::Delimiter::None, false),
+            (T!['('], T![')']) => (Some(tt::Delimiter::Parenthesis), true),
+            (T!['{'], T!['}']) => (Some(tt::Delimiter::Brace), true),
+            (T!['['], T![']']) => (Some(tt::Delimiter::Bracket), true),
+            _ => (None, false),
         };
 
         let mut token_trees = Vec::new();
@@ -246,9 +246,7 @@ impl Convertor {
                 }
                 NodeOrToken::Node(node) => {
                     let child_subtree = self.go(&node)?;
-                    if child_subtree.delimiter == tt::Delimiter::None
-                        && node.kind() != SyntaxKind::TOKEN_TREE
-                    {
+                    if child_subtree.delimiter.is_none() && node.kind() != SyntaxKind::TOKEN_TREE {
                         token_trees.extend(child_subtree.token_trees);
                     } else {
                         token_trees.push(child_subtree.into());
@@ -299,16 +297,16 @@ impl<'a> TtTreeSink<'a> {
     }
 }
 
-fn delim_to_str(d: tt::Delimiter, closing: bool) -> SmolStr {
+fn delim_to_str(d: Option<tt::Delimiter>, closing: bool) -> SmolStr {
     let texts = match d {
-        tt::Delimiter::Parenthesis => "()",
-        tt::Delimiter::Brace => "{}",
-        tt::Delimiter::Bracket => "[]",
-        tt::Delimiter::None => "",
+        Some(tt::Delimiter::Parenthesis) => "()",
+        Some(tt::Delimiter::Brace) => "{}",
+        Some(tt::Delimiter::Bracket) => "[]",
+        None => return "".into(),
     };
 
     let idx = closing as usize;
-    let text = if !texts.is_empty() { &texts[idx..texts.len() - (1 - idx)] } else { "" };
+    let text = &texts[idx..texts.len() - (1 - idx)];
     text.into()
 }
 
@@ -497,7 +495,7 @@ mod tests {
         let token_tree = ast::TokenTree::cast(token_tree).unwrap();
         let tt = ast_to_token_tree(&token_tree).unwrap().0;
 
-        assert_eq!(tt.delimiter, tt::Delimiter::Brace);
+        assert_eq!(tt.delimiter, Some(tt::Delimiter::Brace));
     }
 
     #[test]
diff --git a/crates/ra_mbe/src/tests.rs b/crates/ra_mbe/src/tests.rs
index 0109a4d98..148cc2625 100644
--- a/crates/ra_mbe/src/tests.rs
+++ b/crates/ra_mbe/src/tests.rs
@@ -1463,7 +1463,7 @@ pub(crate) fn assert_expansion(
         let wrapped = ast::SourceFile::parse(&wrapped);
         let wrapped = wrapped.tree().syntax().descendants().find_map(ast::TokenTree::cast).unwrap();
         let mut wrapped = ast_to_token_tree(&wrapped).unwrap().0;
-        wrapped.delimiter = tt::Delimiter::None;
+        wrapped.delimiter = None;
         wrapped
     };
     let (expanded_tree, expected_tree) = match kind {
diff --git a/crates/ra_tt/src/lib.rs b/crates/ra_tt/src/lib.rs
index 4c00b8f30..e7bfd5fd2 100644
--- a/crates/ra_tt/src/lib.rs
+++ b/crates/ra_tt/src/lib.rs
@@ -48,9 +48,9 @@ pub enum Leaf {
 }
 impl_froms!(Leaf: Literal, Punct, Ident);
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Default)]
 pub struct Subtree {
-    pub delimiter: Delimiter,
+    pub delimiter: Option<Delimiter>,
     pub token_trees: Vec<TokenTree>,
 }
 
@@ -59,7 +59,6 @@ pub enum Delimiter {
     Parenthesis,
     Brace,
     Bracket,
-    None,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -97,10 +96,10 @@ impl fmt::Display for TokenTree {
 impl fmt::Display for Subtree {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let (l, r) = match self.delimiter {
-            Delimiter::Parenthesis => ("(", ")"),
-            Delimiter::Brace => ("{", "}"),
-            Delimiter::Bracket => ("[", "]"),
-            Delimiter::None => ("", ""),
+            Some(Delimiter::Parenthesis) => ("(", ")"),
+            Some(Delimiter::Brace) => ("{", "}"),
+            Some(Delimiter::Bracket) => ("[", "]"),
+            None => ("", ""),
         };
         f.write_str(l)?;
         let mut needs_space = false;