72 files changed, 3238 insertions, 973 deletions
diff --git a/crates/flycheck/Cargo.toml b/crates/flycheck/Cargo.toml
index 1d19c7886..2a1a21b28 100644
--- a/crates/flycheck/Cargo.toml
+++ b/crates/flycheck/Cargo.toml
@@ -12,9 +12,9 @@ doctest = false
 [dependencies]
 crossbeam-channel = "0.5.0"
 log = "0.4.8"
-cargo_metadata = "0.12.2"
+cargo_metadata = "0.13"
 serde_json = "1.0.48"
 jod-thread = "0.1.1"
 toolchain = { path = "../toolchain", version = "0.0.0" }
-stdx = { path = "../stdx", version = "0.0.0"  }
+stdx = { path = "../stdx", version = "0.0.0" }
diff --git a/crates/flycheck/src/lib.rs b/crates/flycheck/src/lib.rs
index e04208006..e2a59497a 100644
--- a/crates/flycheck/src/lib.rs
+++ b/crates/flycheck/src/lib.rs
@@ -194,7 +194,7 @@ impl FlycheckActor {
                    cargo_metadata::Message::BuildScriptExecuted(_)
                    | cargo_metadata::Message::BuildFinished(_)
                    | cargo_metadata::Message::TextLine(_)
-                    | cargo_metadata::Message::Unknown => {}
+                    | _ => {}
                },
            }
        }
@@ -329,8 +329,7 @@ impl CargoActor {
            // Skip certain kinds of messages to only spend time on what's useful
            match &message {
                cargo_metadata::Message::CompilerArtifact(artifact) if artifact.fresh => (),
-                cargo_metadata::Message::BuildScriptExecuted(_)
+                cargo_metadata::Message::BuildScriptExecuted(_) => (),
-                | cargo_metadata::Message::Unknown => (),
                _ => self.sender.send(message).unwrap(),
            }
        }
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 00b0dc082..7656db974 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -14,7 +14,7 @@ use hir_def::{
    per_ns::PerNs,
    resolver::{HasResolver, Resolver},
    src::HasSource as _,
-    type_ref::{Mutability, TypeRef},
+    type_ref::TypeRef,
    AdtId, AssocContainerId, AssocItemId, AssocItemLoc, AttrDefId, ConstId, ConstParamId,
    DefWithBodyId, EnumId, FunctionId, GenericDefId, HasModule, ImplId, LifetimeParamId,
    LocalEnumVariantId, LocalFieldId, Lookup, ModuleId, StaticId, StructId, TraitId, TypeAliasId,
@@ -32,8 +32,8 @@ use hir_ty::{
    method_resolution,
    traits::{FnTrait, Solution, SolutionVariables},
    AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, DebruijnIndex, GenericPredicate,
-    InEnvironment, Obligation, ProjectionPredicate, ProjectionTy, Scalar, Substs, TraitEnvironment,
+    InEnvironment, Mutability, Obligation, ProjectionPredicate, ProjectionTy, Scalar, Substs,
-    Ty, TyDefId, TyVariableKind,
+    TraitEnvironment, Ty, TyDefId, TyVariableKind,
 };
 use rustc_hash::FxHashSet;
 use stdx::{format_to, impl_from};
@@ -836,7 +836,7 @@ pub enum Access {
 impl From<Mutability> for Access {
    fn from(mutability: Mutability) -> Access {
        match mutability {
-            Mutability::Shared => Access::Shared,
+            Mutability::Not => Access::Shared,
            Mutability::Mut => Access::Exclusive,
        }
    }
@@ -865,7 +865,10 @@ impl SelfParam {
            .params
            .first()
            .map(|param| match *param {
-                TypeRef::Reference(.., mutability) => mutability.into(),
+                TypeRef::Reference(.., mutability) => match mutability {
+                    hir_def::type_ref::Mutability::Shared => Access::Shared,
+                    hir_def::type_ref::Mutability::Mut => Access::Exclusive,
+                },
                _ => Access::Owned,
            })
            .unwrap_or(Access::Owned)
@@ -1697,7 +1700,7 @@ impl Type {
    pub fn is_packed(&self, db: &dyn HirDatabase) -> bool {
        let adt_id = match self.ty.value {
-            Ty::Adt(adt_id, ..) => adt_id,
+            Ty::Adt(hir_ty::AdtId(adt_id), ..) => adt_id,
            _ => return false,
        };
@@ -1725,8 +1728,8 @@ impl Type {
    pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
        let (variant_id, substs) = match self.ty.value {
-            Ty::Adt(AdtId::StructId(s), ref substs) => (s.into(), substs),
+            Ty::Adt(hir_ty::AdtId(AdtId::StructId(s)), ref substs) => (s.into(), substs),
-            Ty::Adt(AdtId::UnionId(u), ref substs) => (u.into(), substs),
+            Ty::Adt(hir_ty::AdtId(AdtId::UnionId(u)), ref substs) => (u.into(), substs),
            _ => return Vec::new(),
        };
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 769945c47..69fcdab07 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -33,11 +33,11 @@ mod has_source;
 pub use crate::{
    attrs::{HasAttrs, Namespace},
    code_model::{
-        Access, Adt, AsAssocItem, AssocItem, AssocItemContainer, Callable, CallableKind, Const,
+        Access, Adt, AsAssocItem, AssocItem, AssocItemContainer, BuiltinType, Callable,
-        ConstParam, Crate, CrateDependency, DefWithBody, Enum, Field, FieldSource, Function,
+        CallableKind, Const, ConstParam, Crate, CrateDependency, DefWithBody, Enum, Field,
-        GenericDef, GenericParam, HasVisibility, Impl, Label, LifetimeParam, Local, MacroDef,
+        FieldSource, Function, GenericDef, GenericParam, HasVisibility, Impl, Label, LifetimeParam,
-        Module, ModuleDef, ScopeDef, Static, Struct, Trait, Type, TypeAlias, TypeParam, Union,
+        Local, MacroDef, Module, ModuleDef, ScopeDef, Static, Struct, Trait, Type, TypeAlias,
-        Variant, VariantDef,
+        TypeParam, Union, Variant, VariantDef,
    },
    has_source::HasSource,
    semantics::{PathResolution, Semantics, SemanticsScope},
@@ -47,7 +47,6 @@ pub use hir_def::{
    adt::StructKind,
    attr::{Attrs, Documentation},
    body::scope::ExprScopes,
-    builtin_type::BuiltinType,
    find_path::PrefixKind,
    import_map,
    item_scope::ItemInNs,
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index fe4c3fa28..24ffa6c3a 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -367,7 +367,7 @@ fn inner_attributes(
            // Excerpt from the reference:
            // Block expressions accept outer and inner attributes, but only when they are the outer
            // expression of an expression statement or the final expression of another block expression.
-            ast::BlockExpr(it) => return None,
+            ast::BlockExpr(_it) => return None,
            _ => return None,
        }
    };
diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs
index 5e2a711b8..3a98ffbaa 100644
--- a/crates/hir_def/src/find_path.rs
+++ b/crates/hir_def/src/find_path.rs
@@ -1,5 +1,7 @@
 //! An algorithm to find a path to refer to a certain item.
+use std::iter;
 use hir_expand::name::{known, AsName, Name};
 use rustc_hash::FxHashSet;
 use test_utils::mark;
@@ -95,7 +97,7 @@ fn find_path_inner(
    item: ItemInNs,
    from: ModuleId,
    max_len: usize,
-    prefixed: Option<PrefixKind>,
+    mut prefixed: Option<PrefixKind>,
 ) -> Option<ModPath> {
    if max_len == 0 {
        return None;
@@ -114,8 +116,9 @@ fn find_path_inner(
    }
    // - if the item is the crate root, return `crate`
-    let root = def_map.module_id(def_map.root());
+    let root = def_map.crate_root(db);
    if item == ItemInNs::Types(ModuleDefId::ModuleId(root)) && def_map.block_id().is_none() {
+        // FIXME: the `block_id()` check should be unnecessary, but affects the result
        return Some(ModPath::from_segments(PathKind::Crate, Vec::new()));
    }
@@ -165,7 +168,7 @@ fn find_path_inner(
    // - otherwise, look for modules containing (reexporting) it and import it from one of those
-    let crate_root = def_map.module_id(def_map.root());
+    let crate_root = def_map.crate_root(db);
    let crate_attrs = db.attrs(crate_root.into());
    let prefer_no_std = crate_attrs.by_key("no_std").exists();
    let mut best_path = None;
@@ -228,12 +231,16 @@ fn find_path_inner(
        }
    }
-    if let Some(mut prefix) = prefixed.map(PrefixKind::prefix) {
+    // If the item is declared inside a block expression, don't use a prefix, as we don't handle
-        if matches!(prefix, PathKind::Crate | PathKind::Super(0)) && def_map.block_id().is_some() {
+    // that correctly (FIXME).
-            // Inner items cannot be referred to via `crate::` or `self::` paths.
+    if let Some(item_module) = item.as_module_def_id().and_then(|did| did.module(db)) {
-            prefix = PathKind::Plain;
+        if item_module.def_map(db).block_id().is_some() && prefixed.is_some() {
+            mark::hit!(prefixed_in_block_expression);
+            prefixed = Some(PrefixKind::Plain);
        }
+    }
+    if let Some(prefix) = prefixed.map(PrefixKind::prefix) {
        best_path.or_else(|| {
            scope_name.map(|scope_name| ModPath::from_segments(prefix, vec![scope_name]))
        })
@@ -285,12 +292,12 @@ fn find_local_import_locations(
    let data = &def_map[from.local_id];
    let mut worklist =
        data.children.values().map(|child| def_map.module_id(*child)).collect::<Vec<_>>();
-    let mut parent = data.parent;
+    for ancestor in iter::successors(from.containing_module(db), |m| m.containing_module(db)) {
-    while let Some(p) = parent {
+        worklist.push(ancestor);
-        worklist.push(def_map.module_id(p));
-        parent = def_map[p].parent;
    }
+    let def_map = def_map.crate_root(db).def_map(db);
    let mut seen: FxHashSet<_> = FxHashSet::default();
    let mut locations = Vec::new();
@@ -301,7 +308,14 @@ fn find_local_import_locations(
        let ext_def_map;
        let data = if module.krate == from.krate {
-            &def_map[module.local_id]
+            if module.block.is_some() {
+                // Re-query the block's DefMap
+                ext_def_map = module.def_map(db);
+                &ext_def_map[module.local_id]
+            } else {
+                // Reuse the root DefMap
+                &def_map[module.local_id]
+            }
        } else {
            // The crate might reexport a module defined in another crate.
            ext_def_map = module.def_map(db);
@@ -828,6 +842,7 @@ mod tests {
    #[test]
    fn inner_items_from_inner_module() {
+        mark::check!(prefixed_in_block_expression);
        check_found_path(
            r#"
            fn main() {
@@ -847,26 +862,22 @@ mod tests {
    }
    #[test]
-    #[ignore]
+    fn outer_items_with_inner_items_present() {
-    fn inner_items_from_parent_module() {
-        // FIXME: ItemTree currently associates all inner items with `main`. Luckily, this sort of
-        // code is very rare, so this isn't terrible.
-        // To fix it, we should probably build dedicated `ItemTree`s for inner items, and not store
-        // them in the file's main ItemTree. This would also allow us to stop parsing function
-        // bodies when we only want to compute the crate's main DefMap.
        check_found_path(
            r#"
+            mod module {
+                pub struct CompleteMe;
+            }
            fn main() {
-                struct Struct {}
+                fn inner() {}
-                mod module {
+                $0
-                    $0
-                }
            }
-        "#,
+            "#,
-            "super::Struct",
+            "module::CompleteMe",
-            "super::Struct",
+            "module::CompleteMe",
-            "super::Struct",
+            "crate::module::CompleteMe",
-            "super::Struct",
+            "self::module::CompleteMe",
-        );
+        )
    }
 }
diff --git a/crates/hir_def/src/item_scope.rs b/crates/hir_def/src/item_scope.rs
index ee46c3330..4e5daa2ff 100644
--- a/crates/hir_def/src/item_scope.rs
+++ b/crates/hir_def/src/item_scope.rs
@@ -12,8 +12,8 @@ use stdx::format_to;
 use test_utils::mark;
 use crate::{
-    db::DefDatabase, per_ns::PerNs, visibility::Visibility, AdtId, BuiltinType, HasModule, ImplId,
+    db::DefDatabase, per_ns::PerNs, visibility::Visibility, AdtId, BuiltinType, ImplId,
-    LocalModuleId, Lookup, MacroDefId, ModuleDefId, ModuleId, TraitId,
+    LocalModuleId, MacroDefId, ModuleDefId, ModuleId, TraitId,
 };
 #[derive(Copy, Clone)]
@@ -375,19 +375,9 @@ impl ItemInNs {
    /// Returns the crate defining this item (or `None` if `self` is built-in).
    pub fn krate(&self, db: &dyn DefDatabase) -> Option<CrateId> {
-        Some(match self {
+        match self {
-            ItemInNs::Types(did) | ItemInNs::Values(did) => match did {
+            ItemInNs::Types(did) | ItemInNs::Values(did) => did.module(db).map(|m| m.krate),
-                ModuleDefId::ModuleId(id) => id.krate,
+            ItemInNs::Macros(id) => Some(id.krate),
-                ModuleDefId::FunctionId(id) => id.lookup(db).module(db).krate,
+        }
-                ModuleDefId::AdtId(id) => id.module(db).krate,
-                ModuleDefId::EnumVariantId(id) => id.parent.lookup(db).container.module(db).krate,
-                ModuleDefId::ConstId(id) => id.lookup(db).container.module(db).krate,
-                ModuleDefId::StaticId(id) => id.lookup(db).container.module(db).krate,
-                ModuleDefId::TraitId(id) => id.lookup(db).container.module(db).krate,
-                ModuleDefId::TypeAliasId(id) => id.lookup(db).module(db).krate,
-                ModuleDefId::BuiltinType(_) => return None,
-            },
-            ItemInNs::Macros(id) => return Some(id.krate),
-        })
    }
 }
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 6802bc250..4498d94bb 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -97,6 +97,10 @@ impl ModuleId {
    pub fn krate(&self) -> CrateId {
        self.krate
    }
+    pub fn containing_module(&self, db: &dyn db::DefDatabase) -> Option<ModuleId> {
+        self.def_map(db).containing_module(self.local_id)
+    }
 }
 /// An ID of a module, **local** to a specific crate
@@ -529,6 +533,25 @@ impl HasModule for StaticLoc {
    }
 }
+impl ModuleDefId {
+    /// Returns the module containing `self` (or `self`, if `self` is itself a module).
+    ///
+    /// Returns `None` if `self` refers to a primitive type.
+    pub fn module(&self, db: &dyn db::DefDatabase) -> Option<ModuleId> {
+        Some(match self {
+            ModuleDefId::ModuleId(id) => *id,
+            ModuleDefId::FunctionId(id) => id.lookup(db).module(db),
+            ModuleDefId::AdtId(id) => id.module(db),
+            ModuleDefId::EnumVariantId(id) => id.parent.lookup(db).container.module(db),
+            ModuleDefId::ConstId(id) => id.lookup(db).container.module(db),
+            ModuleDefId::StaticId(id) => id.lookup(db).container.module(db),
+            ModuleDefId::TraitId(id) => id.lookup(db).container.module(db),
+            ModuleDefId::TypeAliasId(id) => id.lookup(db).module(db),
+            ModuleDefId::BuiltinType(_) => return None,
+        })
+    }
+}
 impl AttrDefId {
    pub fn krate(&self, db: &dyn db::DefDatabase) -> CrateId {
        match self {
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index 6a3456f2e..003d668ca 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -343,6 +343,18 @@ impl DefMap {
        Some(self.block?.parent)
    }
+    /// Returns the module containing `local_mod`, either the parent `mod`, or the module containing
+    /// the block, if `self` corresponds to a block expression.
+    pub fn containing_module(&self, local_mod: LocalModuleId) -> Option<ModuleId> {
+        match &self[local_mod].parent {
+            Some(parent) => Some(self.module_id(*parent)),
+            None => match &self.block {
+                Some(block) => Some(block.parent),
+                None => None,
+            },
+        }
+    }
    // FIXME: this can use some more human-readable format (ideally, an IR
    // even), as this should be a great debugging aid.
    pub fn dump(&self, db: &dyn DefDatabase) -> String {
diff --git a/crates/hir_def/src/path/lower.rs b/crates/hir_def/src/path/lower.rs
index a469546c1..505493a74 100644
--- a/crates/hir_def/src/path/lower.rs
+++ b/crates/hir_def/src/path/lower.rs
@@ -101,8 +101,12 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
                break;
            }
            ast::PathSegmentKind::SelfKw => {
-                kind = PathKind::Super(0);
+                // don't break out if `self` is the last segment of a path, this mean we got an
-                break;
+                // use tree like `foo::{self}` which we want to resolve as `foo`
+                if !segments.is_empty() {
+                    kind = PathKind::Super(0);
+                    break;
+                }
            }
            ast::PathSegmentKind::SuperKw => {
                let nested_super_count = if let PathKind::Super(n) = kind { n } else { 0 };
@@ -117,6 +121,11 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
    segments.reverse();
    generic_args.reverse();
+    if segments.is_empty() && kind == PathKind::Plain && type_anchor.is_none() {
+        // plain empty paths don't exist, this means we got a single `self` segment as our path
+        kind = PathKind::Super(0);
+    }
    // handle local_inner_macros :
    // Basically, even in rustc it is quite hacky:
    // https://github.com/rust-lang/rust/blob/614f273e9388ddd7804d5cbc80b8865068a3744e/src/librustc_resolve/macros.rs#L456
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index 6ef9d1e7e..d1302d749 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -17,9 +17,9 @@ ena = "0.14.0"
 log = "0.4.8"
 rustc-hash = "1.1.0"
 scoped-tls = "1"
-chalk-solve = { version = "0.58", default-features = false }
+chalk-solve = { version = "0.59", default-features = false }
-chalk-ir = "0.58"
+chalk-ir = "0.59"
-chalk-recursive = "0.58"
+chalk-recursive = "0.59"
 la-arena = { version = "0.2.0", path = "../../lib/arena" }
 stdx = { path = "../stdx", version = "0.0.0" }
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 66a88e2b6..2751cd304 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -2,9 +2,7 @@
 use std::sync::Arc;
-use hir_def::{
+use hir_def::{expr::Statement, path::path, resolver::HasResolver, AssocItemId, DefWithBodyId};
-    expr::Statement, path::path, resolver::HasResolver, AdtId, AssocItemId, DefWithBodyId,
-};
 use hir_expand::{diagnostics::DiagnosticSink, name};
 use rustc_hash::FxHashSet;
 use syntax::{ast, AstPtr};
@@ -17,7 +15,7 @@ use crate::{
        MissingPatFields, RemoveThisSemicolon,
    },
    utils::variant_data,
-    InferenceResult, Ty,
+    AdtId, InferenceResult, Ty,
 };
 pub(crate) use hir_def::{
@@ -382,10 +380,14 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
        };
        let (params, required) = match mismatch.expected {
-            Ty::Adt(AdtId::EnumId(enum_id), ref parameters) if enum_id == core_result_enum => {
+            Ty::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref parameters)
+                if enum_id == core_result_enum =>
+            {
                (parameters, "Ok".to_string())
            }
-            Ty::Adt(AdtId::EnumId(enum_id), ref parameters) if enum_id == core_option_enum => {
+            Ty::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ref parameters)
+                if enum_id == core_option_enum =>
+            {
                (parameters, "Some".to_string())
            }
            _ => return,
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index 86fee0050..04d39c571 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -222,12 +222,12 @@ use hir_def::{
    adt::VariantData,
    body::Body,
    expr::{Expr, Literal, Pat, PatId},
-    AdtId, EnumVariantId, StructId, VariantId,
+    EnumVariantId, StructId, VariantId,
 };
 use la_arena::Idx;
 use smallvec::{smallvec, SmallVec};
-use crate::{db::HirDatabase, InferenceResult, Ty};
+use crate::{db::HirDatabase, AdtId, InferenceResult, Ty};
 #[derive(Debug, Clone, Copy)]
 /// Either a pattern from the source code being analyzed, represented as
@@ -627,7 +627,7 @@ pub(super) fn is_useful(
    // - `!` type
    // In those cases, no match arm is useful.
    match cx.infer[cx.match_expr].strip_references() {
-        Ty::Adt(AdtId::EnumId(enum_id), ..) => {
+        Ty::Adt(AdtId(hir_def::AdtId::EnumId(enum_id)), ..) => {
            if cx.db.enum_data(*enum_id).variants.is_empty() {
                return Ok(Usefulness::NotUseful);
            }
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index f3a4333cb..a0882a2a1 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -2,18 +2,20 @@
 use std::{borrow::Cow, fmt};
-use crate::{
-    db::HirDatabase, primitive, utils::generics, AliasTy, CallableDefId, CallableSig,
-    GenericPredicate, Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs,
-    TraitRef, Ty,
-};
 use arrayvec::ArrayVec;
+use chalk_ir::Mutability;
 use hir_def::{
-    db::DefDatabase, find_path, generics::TypeParamProvenance, item_scope::ItemInNs, AdtId,
+    db::DefDatabase, find_path, generics::TypeParamProvenance, item_scope::ItemInNs,
    AssocContainerId, HasModule, Lookup, ModuleId, TraitId,
 };
 use hir_expand::name::Name;
+use crate::{
+    db::HirDatabase, primitive, utils::generics, AdtId, AliasTy, CallableDefId, CallableSig,
+    GenericPredicate, Lifetime, Obligation, OpaqueTy, OpaqueTyId, ProjectionTy, Scalar, Substs,
+    TraitRef, Ty,
+};
 pub struct HirFormatter<'a> {
    pub db: &'a dyn HirDatabase,
    fmt: &'a mut dyn fmt::Write,
@@ -291,9 +293,23 @@ impl HirDisplay for Ty {
                    t.into_displayable(f.db, f.max_size, f.omit_verbose_types, f.display_target);
                if matches!(self, Ty::Raw(..)) {
-                    write!(f, "*{}", m.as_keyword_for_ptr())?;
+                    write!(
+                        f,
+                        "*{}",
+                        match m {
+                            Mutability::Not => "const ",
+                            Mutability::Mut => "mut ",
+                        }
+                    )?;
                } else {
-                    write!(f, "&{}", m.as_keyword_for_ref())?;
+                    write!(
+                        f,
+                        "&{}",
+                        match m {
+                            Mutability::Not => "",
+                            Mutability::Mut => "mut ",
+                        }
+                    )?;
                }
                let datas;
@@ -385,13 +401,13 @@ impl HirDisplay for Ty {
                    write!(f, " -> {}", ret_display)?;
                }
            }
-            Ty::Adt(def_id, parameters) => {
+            Ty::Adt(AdtId(def_id), parameters) => {
                match f.display_target {
                    DisplayTarget::Diagnostics | DisplayTarget::Test => {
                        let name = match *def_id {
-                            AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
+                            hir_def::AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
-                            AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
+                            hir_def::AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
-                            AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
+                            hir_def::AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
                        };
                        write!(f, "{}", name)?;
                    }
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 18a4f5e8a..4d771a91e 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -18,6 +18,7 @@ use std::mem;
 use std::ops::Index;
 use std::sync::Arc;
+use chalk_ir::Mutability;
 use hir_def::{
    body::Body,
    data::{ConstData, FunctionData, StaticData},
@@ -25,7 +26,7 @@ use hir_def::{
    lang_item::LangItemTarget,
    path::{path, Path},
    resolver::{HasResolver, Resolver, TypeNs},
-    type_ref::{Mutability, TypeRef},
+    type_ref::TypeRef,
    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, FunctionId, Lookup, TraitId,
    TypeAliasId, VariantId,
 };
@@ -87,7 +88,7 @@ impl BindingMode {
    fn convert(annotation: BindingAnnotation) -> BindingMode {
        match annotation {
            BindingAnnotation::Unannotated | BindingAnnotation::Mutable => BindingMode::Move,
-            BindingAnnotation::Ref => BindingMode::Ref(Mutability::Shared),
+            BindingAnnotation::Ref => BindingMode::Ref(Mutability::Not),
            BindingAnnotation::RefMut => BindingMode::Ref(Mutability::Mut),
        }
    }
diff --git a/crates/hir_ty/src/infer/coerce.rs b/crates/hir_ty/src/infer/coerce.rs
index c33d8c61e..cf0a3add4 100644
--- a/crates/hir_ty/src/infer/coerce.rs
+++ b/crates/hir_ty/src/infer/coerce.rs
@@ -4,8 +4,8 @@
 //!
 //! See: https://doc.rust-lang.org/nomicon/coercions.html
-use chalk_ir::TyVariableKind;
+use chalk_ir::{Mutability, TyVariableKind};
-use hir_def::{lang_item::LangItemTarget, type_ref::Mutability};
+use hir_def::lang_item::LangItemTarget;
 use test_utils::mark;
 use crate::{autoderef, traits::Solution, Obligation, Substs, TraitRef, Ty};
@@ -73,20 +73,20 @@ impl<'a> InferenceContext<'a> {
        match (&mut from_ty, to_ty) {
            // `*mut T` -> `*const T`
            // `&mut T` -> `&T`
-            (Ty::Raw(m1, ..), Ty::Raw(m2 @ Mutability::Shared, ..))
+            (Ty::Raw(m1, ..), Ty::Raw(m2 @ Mutability::Not, ..))
-            | (Ty::Ref(m1, ..), Ty::Ref(m2 @ Mutability::Shared, ..)) => {
+            | (Ty::Ref(m1, ..), Ty::Ref(m2 @ Mutability::Not, ..)) => {
                *m1 = *m2;
            }
            // `&T` -> `*const T`
            // `&mut T` -> `*mut T`/`*const T`
-            (Ty::Ref(.., substs), &Ty::Raw(m2 @ Mutability::Shared, ..))
+            (Ty::Ref(.., substs), &Ty::Raw(m2 @ Mutability::Not, ..))
            | (Ty::Ref(Mutability::Mut, substs), &Ty::Raw(m2, ..)) => {
                from_ty = Ty::Raw(m2, substs.clone());
            }
            // Illegal mutability conversion
-            (Ty::Raw(Mutability::Shared, ..), Ty::Raw(Mutability::Mut, ..))
+            (Ty::Raw(Mutability::Not, ..), Ty::Raw(Mutability::Mut, ..))
-            | (Ty::Ref(Mutability::Shared, ..), Ty::Ref(Mutability::Mut, ..)) => return false,
+            | (Ty::Ref(Mutability::Not, ..), Ty::Ref(Mutability::Mut, ..)) => return false,
            // `{function_type}` -> `fn()`
            (Ty::FnDef(..), Ty::Function { .. }) => match from_ty.callable_sig(self.db) {
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 7852b3d23..ec2c13154 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -3,23 +3,25 @@
 use std::iter::{repeat, repeat_with};
 use std::{mem, sync::Arc};
-use chalk_ir::TyVariableKind;
+use chalk_ir::{Mutability, TyVariableKind};
 use hir_def::{
    expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
    path::{GenericArg, GenericArgs},
    resolver::resolver_for_expr,
-    AdtId, AssocContainerId, FieldId, Lookup,
+    AssocContainerId, FieldId, Lookup,
 };
 use hir_expand::name::{name, Name};
 use syntax::ast::RangeOp;
 use test_utils::mark;
 use crate::{
-    autoderef, method_resolution, op,
+    autoderef,
+    lower::lower_to_chalk_mutability,
+    method_resolution, op,
    primitive::{self, UintTy},
    traits::{FnTrait, InEnvironment},
    utils::{generics, variant_data, Generics},
-    Binders, CallableDefId, FnPointer, FnSig, Mutability, Obligation, OpaqueTyId, Rawness, Scalar,
+    AdtId, Binders, CallableDefId, FnPointer, FnSig, Obligation, OpaqueTyId, Rawness, Scalar,
    Substs, TraitRef, Ty,
 };
@@ -427,14 +429,14 @@ impl<'a> InferenceContext<'a> {
                    Ty::Tuple(_, substs) => {
                        name.as_tuple_index().and_then(|idx| substs.0.get(idx).cloned())
                    }
-                    Ty::Adt(AdtId::StructId(s), parameters) => {
+                    Ty::Adt(AdtId(hir_def::AdtId::StructId(s)), parameters) => {
                        self.db.struct_data(s).variant_data.field(name).map(|local_id| {
                            let field = FieldId { parent: s.into(), local_id };
                            self.write_field_resolution(tgt_expr, field);
                            self.db.field_types(s.into())[field.local_id].clone().subst(&parameters)
                        })
                    }
-                    Ty::Adt(AdtId::UnionId(u), parameters) => {
+                    Ty::Adt(AdtId(hir_def::AdtId::UnionId(u)), parameters) => {
                        self.db.union_data(u).variant_data.field(name).map(|local_id| {
                            let field = FieldId { parent: u.into(), local_id };
                            self.write_field_resolution(tgt_expr, field);
@@ -462,10 +464,11 @@ impl<'a> InferenceContext<'a> {
                cast_ty
            }
            Expr::Ref { expr, rawness, mutability } => {
+                let mutability = lower_to_chalk_mutability(*mutability);
                let expectation = if let Some((exp_inner, exp_rawness, exp_mutability)) =
                    &expected.ty.as_reference_or_ptr()
                {
-                    if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
+                    if *exp_mutability == Mutability::Mut && mutability == Mutability::Not {
                        // FIXME: throw type error - expected mut reference but found shared ref,
                        // which cannot be coerced
                    }
@@ -479,8 +482,8 @@ impl<'a> InferenceContext<'a> {
                };
                let inner_ty = self.infer_expr_inner(*expr, &expectation);
                match rawness {
-                    Rawness::RawPtr => Ty::Raw(*mutability, Substs::single(inner_ty)),
+                    Rawness::RawPtr => Ty::Raw(mutability, Substs::single(inner_ty)),
-                    Rawness::Ref => Ty::Ref(*mutability, Substs::single(inner_ty)),
+                    Rawness::Ref => Ty::Ref(mutability, Substs::single(inner_ty)),
                }
            }
            Expr::Box { expr } => {
@@ -495,7 +498,7 @@ impl<'a> InferenceContext<'a> {
                        _ => (),
                    }
                    sb = sb.fill(repeat_with(|| self.table.new_type_var()));
-                    Ty::Adt(box_, sb.build())
+                    Ty::adt_ty(box_, sb.build())
                } else {
                    Ty::Unknown
                }
@@ -583,31 +586,31 @@ impl<'a> InferenceContext<'a> {
                let rhs_ty = rhs.map(|e| self.infer_expr(e, &rhs_expect));
                match (range_type, lhs_ty, rhs_ty) {
                    (RangeOp::Exclusive, None, None) => match self.resolve_range_full() {
-                        Some(adt) => Ty::Adt(adt, Substs::empty()),
+                        Some(adt) => Ty::adt_ty(adt, Substs::empty()),
                        None => Ty::Unknown,
                    },
                    (RangeOp::Exclusive, None, Some(ty)) => match self.resolve_range_to() {
-                        Some(adt) => Ty::Adt(adt, Substs::single(ty)),
+                        Some(adt) => Ty::adt_ty(adt, Substs::single(ty)),
                        None => Ty::Unknown,
                    },
                    (RangeOp::Inclusive, None, Some(ty)) => {
                        match self.resolve_range_to_inclusive() {
-                            Some(adt) => Ty::Adt(adt, Substs::single(ty)),
+                            Some(adt) => Ty::adt_ty(adt, Substs::single(ty)),
                            None => Ty::Unknown,
                        }
                    }
                    (RangeOp::Exclusive, Some(_), Some(ty)) => match self.resolve_range() {
-                        Some(adt) => Ty::Adt(adt, Substs::single(ty)),
+                        Some(adt) => Ty::adt_ty(adt, Substs::single(ty)),
                        None => Ty::Unknown,
                    },
                    (RangeOp::Inclusive, Some(_), Some(ty)) => {
                        match self.resolve_range_inclusive() {
-                            Some(adt) => Ty::Adt(adt, Substs::single(ty)),
+                            Some(adt) => Ty::adt_ty(adt, Substs::single(ty)),
                            None => Ty::Unknown,
                        }
                    }
                    (RangeOp::Exclusive, Some(ty), None) => match self.resolve_range_from() {
-                        Some(adt) => Ty::Adt(adt, Substs::single(ty)),
+                        Some(adt) => Ty::adt_ty(adt, Substs::single(ty)),
                        None => Ty::Unknown,
                    },
                    (RangeOp::Inclusive, _, None) => Ty::Unknown,
@@ -684,11 +687,11 @@ impl<'a> InferenceContext<'a> {
            }
            Expr::Literal(lit) => match lit {
                Literal::Bool(..) => Ty::Scalar(Scalar::Bool),
-                Literal::String(..) => Ty::Ref(Mutability::Shared, Substs::single(Ty::Str)),
+                Literal::String(..) => Ty::Ref(Mutability::Not, Substs::single(Ty::Str)),
                Literal::ByteString(..) => {
                    let byte_type = Ty::Scalar(Scalar::Uint(UintTy::U8));
                    let array_type = Ty::Array(Substs::single(byte_type));
-                    Ty::Ref(Mutability::Shared, Substs::single(array_type))
+                    Ty::Ref(Mutability::Not, Substs::single(array_type))
                }
                Literal::Char(..) => Ty::Scalar(Scalar::Char),
                Literal::Int(_v, ty) => match ty {
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index a318e47f3..987793e2e 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -3,17 +3,17 @@
 use std::iter::repeat;
 use std::sync::Arc;
+use chalk_ir::Mutability;
 use hir_def::{
    expr::{BindingAnnotation, Expr, Literal, Pat, PatId, RecordFieldPat},
    path::Path,
-    type_ref::Mutability,
    FieldId,
 };
 use hir_expand::name::Name;
 use test_utils::mark;
 use super::{BindingMode, Expectation, InferenceContext};
-use crate::{utils::variant_data, Substs, Ty};
+use crate::{lower::lower_to_chalk_mutability, utils::variant_data, Substs, Ty};
 impl<'a> InferenceContext<'a> {
    fn infer_tuple_struct_pat(
@@ -103,7 +103,7 @@ impl<'a> InferenceContext<'a> {
                expected = inner;
                default_bm = match default_bm {
                    BindingMode::Move => BindingMode::Ref(mutability),
-                    BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared),
+                    BindingMode::Ref(Mutability::Not) => BindingMode::Ref(Mutability::Not),
                    BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
                }
            }
@@ -152,9 +152,10 @@ impl<'a> InferenceContext<'a> {
                }
            }
            Pat::Ref { pat, mutability } => {
+                let mutability = lower_to_chalk_mutability(*mutability);
                let expectation = match expected.as_reference() {
                    Some((inner_ty, exp_mut)) => {
-                        if *mutability != exp_mut {
+                        if mutability != exp_mut {
                            // FIXME: emit type error?
                        }
                        inner_ty
@@ -162,7 +163,7 @@ impl<'a> InferenceContext<'a> {
                    _ => &Ty::Unknown,
                };
                let subty = self.infer_pat(*pat, expectation, default_bm);
-                Ty::Ref(*mutability, Substs::single(subty))
+                Ty::Ref(mutability, Substs::single(subty))
            }
            Pat::TupleStruct { path: p, args: subpats, ellipsis } => self.infer_tuple_struct_pat(
                p.as_ref(),
@@ -236,7 +237,7 @@ impl<'a> InferenceContext<'a> {
                    };
                    let inner_ty = self.infer_pat(*inner, inner_expected, default_bm);
-                    Ty::Adt(box_adt, Substs::single(inner_ty))
+                    Ty::adt_ty(box_adt, Substs::single(inner_ty))
                }
                None => Ty::Unknown,
            },
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index 9bcaf6fa7..e77f24e4e 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -27,11 +27,9 @@ use std::{iter, mem, ops::Deref, sync::Arc};
 use base_db::salsa;
 use hir_def::{
-    builtin_type::BuiltinType,
+    builtin_type::BuiltinType, expr::ExprId, type_ref::Rawness, AssocContainerId, DefWithBodyId,
-    expr::ExprId,
+    FunctionId, GenericDefId, HasModule, LifetimeParamId, Lookup, TraitId, TypeAliasId,
-    type_ref::{Mutability, Rawness},
+    TypeParamId,
-    AdtId, AssocContainerId, DefWithBodyId, FunctionId, GenericDefId, HasModule, LifetimeParamId,
-    Lookup, TraitId, TypeAliasId, TypeParamId,
 };
 use itertools::Itertools;
@@ -49,7 +47,9 @@ pub use lower::{
 };
 pub use traits::{InEnvironment, Obligation, ProjectionPredicate, TraitEnvironment};
-pub use chalk_ir::{BoundVar, DebruijnIndex, Scalar, TyVariableKind};
+pub use chalk_ir::{AdtId, BoundVar, DebruijnIndex, Mutability, Scalar, TyVariableKind};
+pub(crate) use crate::traits::chalk::Interner;
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Lifetime {
@@ -133,7 +133,7 @@ pub enum AliasTy {
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Ty {
    /// Structures, enumerations and unions.
-    Adt(AdtId, Substs),
+    Adt(AdtId<Interner>, Substs),
    /// Represents an associated item like `Iterator::Item`.  This is used
    /// when we have tried to normalize a projection like `T::Item` but
@@ -604,6 +604,10 @@ impl Ty {
        Ty::Tuple(0, Substs::empty())
    }
+    pub fn adt_ty(adt: hir_def::AdtId, substs: Substs) -> Ty {
+        Ty::Adt(AdtId(adt), substs)
+    }
    pub fn fn_ptr(sig: CallableSig) -> Self {
        Ty::Function(FnPointer {
            num_args: sig.params().len(),
@@ -652,9 +656,9 @@ impl Ty {
        t
    }
-    pub fn as_adt(&self) -> Option<(AdtId, &Substs)> {
+    pub fn as_adt(&self) -> Option<(hir_def::AdtId, &Substs)> {
        match self {
-            Ty::Adt(adt_def, parameters) => Some((*adt_def, parameters)),
+            Ty::Adt(AdtId(adt), parameters) => Some((*adt, parameters)),
            _ => None,
        }
    }
@@ -668,7 +672,7 @@ impl Ty {
    pub fn as_generic_def(&self) -> Option<GenericDefId> {
        match *self {
-            Ty::Adt(adt, ..) => Some(adt.into()),
+            Ty::Adt(AdtId(adt), ..) => Some(adt.into()),
            Ty::FnDef(callable, ..) => Some(callable.into()),
            Ty::AssociatedType(type_alias, ..) => Some(type_alias.into()),
            Ty::ForeignType(type_alias, ..) => Some(type_alias.into()),
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index ca06c9fe2..5fe5b8ad1 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -8,6 +8,7 @@
 use std::{iter, sync::Arc};
 use base_db::CrateId;
+use chalk_ir::Mutability;
 use hir_def::{
    adt::StructKind,
    builtin_type::BuiltinType,
@@ -157,7 +158,7 @@ impl Ty {
            }
            TypeRef::RawPtr(inner, mutability) => {
                let inner_ty = Ty::from_hir(ctx, inner);
-                Ty::Raw(*mutability, Substs::single(inner_ty))
+                Ty::Raw(lower_to_chalk_mutability(*mutability), Substs::single(inner_ty))
            }
            TypeRef::Array(inner) => {
                let inner_ty = Ty::from_hir(ctx, inner);
@@ -169,7 +170,7 @@ impl Ty {
            }
            TypeRef::Reference(inner, _, mutability) => {
                let inner_ty = Ty::from_hir(ctx, inner);
-                Ty::Ref(*mutability, Substs::single(inner_ty))
+                Ty::Ref(lower_to_chalk_mutability(*mutability), Substs::single(inner_ty))
            }
            TypeRef::Placeholder => Ty::Unknown,
            TypeRef::Fn(params, is_varargs) => {
@@ -1099,7 +1100,7 @@ fn type_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -
 fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
    let generics = generics(db.upcast(), adt.into());
    let substs = Substs::bound_vars(&generics, DebruijnIndex::INNERMOST);
-    Binders::new(substs.len(), Ty::Adt(adt, substs))
+    Binders::new(substs.len(), Ty::adt_ty(adt, substs))
 }
 fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
@@ -1259,3 +1260,10 @@ pub(crate) fn return_type_impl_traits(
        Some(Arc::new(Binders::new(num_binders, return_type_impl_traits)))
    }
 }
+pub(crate) fn lower_to_chalk_mutability(m: hir_def::type_ref::Mutability) -> Mutability {
+    match m {
+        hir_def::type_ref::Mutability::Shared => Mutability::Not,
+        hir_def::type_ref::Mutability::Mut => Mutability::Mut,
+    }
+}
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index dd5109d4e..dfcf346fb 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -6,9 +6,10 @@ use std::{iter, sync::Arc};
 use arrayvec::ArrayVec;
 use base_db::CrateId;
+use chalk_ir::Mutability;
 use hir_def::{
-    lang_item::LangItemTarget, type_ref::Mutability, AdtId, AssocContainerId, AssocItemId,
+    lang_item::LangItemTarget, AssocContainerId, AssocItemId, FunctionId, GenericDefId, HasModule,
-    FunctionId, GenericDefId, HasModule, ImplId, Lookup, ModuleId, TraitId, TypeAliasId,
+    ImplId, Lookup, ModuleId, TraitId, TypeAliasId,
 };
 use hir_expand::name::Name;
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -18,8 +19,8 @@ use crate::{
    db::HirDatabase,
    primitive::{self, FloatTy, IntTy, UintTy},
    utils::all_super_traits,
-    Canonical, DebruijnIndex, FnPointer, FnSig, InEnvironment, Scalar, Substs, TraitEnvironment,
+    AdtId, Canonical, DebruijnIndex, FnPointer, FnSig, InEnvironment, Scalar, Substs,
-    TraitRef, Ty, TypeWalk,
+    TraitEnvironment, TraitRef, Ty, TypeWalk,
 };
 /// This is used as a key for indexing impls.
@@ -31,7 +32,7 @@ pub enum TyFingerprint {
    Never,
    RawPtr(Mutability),
    Scalar(Scalar),
-    Adt(AdtId),
+    Adt(hir_def::AdtId),
    Dyn(TraitId),
    Tuple(usize),
    ForeignType(TypeAliasId),
@@ -49,7 +50,7 @@ impl TyFingerprint {
            &Ty::Slice(..) => TyFingerprint::Slice,
            &Ty::Array(..) => TyFingerprint::Array,
            &Ty::Scalar(scalar) => TyFingerprint::Scalar(scalar),
-            &Ty::Adt(adt, _) => TyFingerprint::Adt(adt),
+            &Ty::Adt(AdtId(adt), _) => TyFingerprint::Adt(adt),
            &Ty::Tuple(cardinality, _) => TyFingerprint::Tuple(cardinality),
            &Ty::Raw(mutability, ..) => TyFingerprint::RawPtr(mutability),
            &Ty::ForeignType(alias_id, ..) => TyFingerprint::ForeignType(alias_id),
@@ -230,7 +231,7 @@ impl Ty {
        let mod_to_crate_ids = |module: ModuleId| Some(std::iter::once(module.krate()).collect());
        let lang_item_targets = match self {
-            Ty::Adt(def_id, _) => {
+            Ty::Adt(AdtId(def_id), _) => {
                return mod_to_crate_ids(def_id.module(db.upcast()));
            }
            Ty::ForeignType(type_alias_id) => {
@@ -251,7 +252,7 @@ impl Ty {
            }
            Ty::Str => lang_item_crate!("str_alloc", "str"),
            Ty::Slice(_) => lang_item_crate!("slice_alloc", "slice"),
-            Ty::Raw(Mutability::Shared, _) => lang_item_crate!("const_ptr"),
+            Ty::Raw(Mutability::Not, _) => lang_item_crate!("const_ptr"),
            Ty::Raw(Mutability::Mut, _) => lang_item_crate!("mut_ptr"),
            Ty::Dyn(_) => {
                return self.dyn_trait().and_then(|trait_| {
@@ -429,7 +430,7 @@ fn iterate_method_candidates_with_autoref(
    }
    let refed = Canonical {
        kinds: deref_chain[0].kinds.clone(),
-        value: Ty::Ref(Mutability::Shared, Substs::single(deref_chain[0].value.clone())),
+        value: Ty::Ref(Mutability::Not, Substs::single(deref_chain[0].value.clone())),
    };
    if iterate_method_candidates_by_receiver(
        &refed,
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index e513fa8f4..4378a9723 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -315,9 +315,8 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
        let id = from_chalk(self.db, trait_id);
        self.db.trait_data(id).name.to_string()
    }
-    fn adt_name(&self, adt_id: chalk_ir::AdtId<Interner>) -> String {
+    fn adt_name(&self, chalk_ir::AdtId(adt_id): AdtId) -> String {
-        let id = from_chalk(self.db, adt_id);
+        match adt_id {
-        match id {
            hir_def::AdtId::StructId(id) => self.db.struct_data(id).name.to_string(),
            hir_def::AdtId::EnumId(id) => self.db.enum_data(id).name.to_string(),
            hir_def::AdtId::UnionId(id) => self.db.union_data(id).name.to_string(),
@@ -488,8 +487,8 @@ pub(crate) fn struct_datum_query(
    struct_id: AdtId,
 ) -> Arc<StructDatum> {
    debug!("struct_datum {:?}", struct_id);
-    let adt_id = from_chalk(db, struct_id);
+    let type_ctor = Ty::Adt(struct_id, Substs::empty());
-    let type_ctor = Ty::Adt(adt_id, Substs::empty());
+    let chalk_ir::AdtId(adt_id) = struct_id;
    debug!("struct {:?} = {:?}", struct_id, type_ctor);
    let num_params = generics(db.upcast(), adt_id.into()).len();
    let upstream = adt_id.module(db.upcast()).krate() != krate;
@@ -684,10 +683,9 @@ pub(crate) fn fn_def_variance_query(
 pub(crate) fn adt_variance_query(
    db: &dyn HirDatabase,
    _krate: CrateId,
-    adt_id: AdtId,
+    chalk_ir::AdtId(adt_id): AdtId,
 ) -> Variances {
-    let adt: crate::AdtId = from_chalk(db, adt_id);
+    let generic_params = generics(db.upcast(), adt_id.into());
-    let generic_params = generics(db.upcast(), adt.into());
    Variances::from_iter(
        &Interner,
        std::iter::repeat(chalk_ir::Variance::Invariant).take(generic_params.len()),
diff --git a/crates/hir_ty/src/traits/chalk/mapping.rs b/crates/hir_ty/src/traits/chalk/mapping.rs
index 6e6055d80..3a08b67e9 100644
--- a/crates/hir_ty/src/traits/chalk/mapping.rs
+++ b/crates/hir_ty/src/traits/chalk/mapping.rs
@@ -10,7 +10,7 @@ use chalk_ir::{
 use chalk_solve::rust_ir;
 use base_db::salsa::InternKey;
-use hir_def::{type_ref::Mutability, AssocContainerId, GenericDefId, Lookup, TypeAliasId};
+use hir_def::{AssocContainerId, GenericDefId, Lookup, TypeAliasId};
 use crate::{
    db::HirDatabase,
@@ -65,7 +65,7 @@ impl ToChalk for Ty {
            }
            Ty::Raw(mutability, substs) => {
                let ty = substs[0].clone().to_chalk(db);
-                chalk_ir::TyKind::Raw(mutability.to_chalk(db), ty).intern(&Interner)
+                chalk_ir::TyKind::Raw(mutability, ty).intern(&Interner)
            }
            Ty::Slice(substs) => {
                chalk_ir::TyKind::Slice(substs[0].clone().to_chalk(db)).intern(&Interner)
@@ -86,7 +86,7 @@ impl ToChalk for Ty {
            Ty::Adt(adt_id, substs) => {
                let substitution = substs.to_chalk(db);
-                chalk_ir::TyKind::Adt(chalk_ir::AdtId(adt_id), substitution).intern(&Interner)
+                chalk_ir::TyKind::Adt(adt_id, substitution).intern(&Interner)
            }
            Ty::Alias(AliasTy::Projection(proj_ty)) => {
                let associated_ty_id = TypeAliasAsAssocType(proj_ty.associated_ty).to_chalk(db);
@@ -183,7 +183,7 @@ impl ToChalk for Ty {
                Ty::Dyn(predicates)
            }
-            chalk_ir::TyKind::Adt(struct_id, subst) => Ty::Adt(struct_id.0, from_chalk(db, subst)),
+            chalk_ir::TyKind::Adt(adt_id, subst) => Ty::Adt(adt_id, from_chalk(db, subst)),
            chalk_ir::TyKind::AssociatedType(type_id, subst) => Ty::AssociatedType(
                from_chalk::<TypeAliasAsAssocType, _>(db, type_id).0,
                from_chalk(db, subst),
@@ -198,11 +198,11 @@ impl ToChalk for Ty {
                Ty::Tuple(cardinality, from_chalk(db, subst))
            }
            chalk_ir::TyKind::Raw(mutability, ty) => {
-                Ty::Raw(from_chalk(db, mutability), Substs::single(from_chalk(db, ty)))
+                Ty::Raw(mutability, Substs::single(from_chalk(db, ty)))
            }
            chalk_ir::TyKind::Slice(ty) => Ty::Slice(Substs::single(from_chalk(db, ty))),
            chalk_ir::TyKind::Ref(mutability, _lifetime, ty) => {
-                Ty::Ref(from_chalk(db, mutability), Substs::single(from_chalk(db, ty)))
+                Ty::Ref(mutability, Substs::single(from_chalk(db, ty)))
            }
            chalk_ir::TyKind::Str => Ty::Str,
            chalk_ir::TyKind::Never => Ty::Never,
@@ -230,12 +230,12 @@ impl ToChalk for Ty {
 /// fake lifetime here, because Chalks built-in logic may expect it to be there.
 fn ref_to_chalk(
    db: &dyn HirDatabase,
-    mutability: Mutability,
+    mutability: chalk_ir::Mutability,
    subst: Substs,
 ) -> chalk_ir::Ty<Interner> {
    let arg = subst[0].clone().to_chalk(db);
    let lifetime = LifetimeData::Static.intern(&Interner);
-    chalk_ir::TyKind::Ref(mutability.to_chalk(db), lifetime, arg).intern(&Interner)
+    chalk_ir::TyKind::Ref(mutability, lifetime, arg).intern(&Interner)
 }
 /// We currently don't model constants, but Chalk does. So, we have to insert a
@@ -313,22 +313,6 @@ impl ToChalk for OpaqueTyId {
    }
 }
-impl ToChalk for Mutability {
-    type Chalk = chalk_ir::Mutability;
-    fn to_chalk(self, _db: &dyn HirDatabase) -> Self::Chalk {
-        match self {
-            Mutability::Shared => chalk_ir::Mutability::Not,
-            Mutability::Mut => chalk_ir::Mutability::Mut,
-        }
-    }
-    fn from_chalk(_db: &dyn HirDatabase, chalk: Self::Chalk) -> Self {
-        match chalk {
-            chalk_ir::Mutability::Mut => Mutability::Mut,
-            chalk_ir::Mutability::Not => Mutability::Shared,
-        }
-    }
-}
 impl ToChalk for hir_def::ImplId {
    type Chalk = ImplId;
@@ -341,18 +325,6 @@ impl ToChalk for hir_def::ImplId {
    }
 }
-impl ToChalk for hir_def::AdtId {
-    type Chalk = AdtId;
-    fn to_chalk(self, _db: &dyn HirDatabase) -> Self::Chalk {
-        chalk_ir::AdtId(self.into())
-    }
-    fn from_chalk(_db: &dyn HirDatabase, id: AdtId) -> Self {
-        id.0
-    }
-}
 impl ToChalk for CallableDefId {
    type Chalk = FnDefId;
diff --git a/crates/ide/src/folding_ranges.rs b/crates/ide/src/folding_ranges.rs
index 45170dd29..4b1b24562 100644
--- a/crates/ide/src/folding_ranges.rs
+++ b/crates/ide/src/folding_ranges.rs
@@ -6,7 +6,7 @@ use syntax::{
    ast::{self, AstNode, AstToken, VisibilityOwner},
    Direction, NodeOrToken, SourceFile,
    SyntaxKind::{self, *},
-    SyntaxNode, TextRange,
+    SyntaxNode, TextRange, TextSize,
 };
 #[derive(Debug, PartialEq, Eq)]
@@ -16,6 +16,7 @@ pub enum FoldKind {
    Mods,
    Block,
    ArgList,
+    Region,
 }
 #[derive(Debug)]
@@ -29,6 +30,8 @@ pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
    let mut visited_comments = FxHashSet::default();
    let mut visited_imports = FxHashSet::default();
    let mut visited_mods = FxHashSet::default();
+    // regions can be nested, here is a LIFO buffer
+    let mut regions_starts: Vec<TextSize> = vec![];
    for element in file.syntax().descendants_with_tokens() {
        // Fold items that span multiple lines
@@ -48,10 +51,25 @@ pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
                // Fold groups of comments
                if let Some(comment) = ast::Comment::cast(token) {
                    if !visited_comments.contains(&comment) {
-                        if let Some(range) =
+                        // regions are not real comments
-                            contiguous_range_for_comment(comment, &mut visited_comments)
+                        if comment.text().trim().starts_with("// region:") {
-                        {
+                            regions_starts.push(comment.syntax().text_range().start());
-                            res.push(Fold { range, kind: FoldKind::Comment })
+                        } else if comment.text().trim().starts_with("// endregion") {
+                            if let Some(region) = regions_starts.pop() {
+                                res.push(Fold {
+                                    range: TextRange::new(
+                                        region,
+                                        comment.syntax().text_range().end(),
+                                    ),
+                                    kind: FoldKind::Region,
+                                })
+                            }
+                        } else {
+                            if let Some(range) =
+                                contiguous_range_for_comment(comment, &mut visited_comments)
+                            {
+                                res.push(Fold { range, kind: FoldKind::Comment })
+                            }
                        }
                    }
                }
@@ -175,9 +193,16 @@ fn contiguous_range_for_comment(
                }
                if let Some(c) = ast::Comment::cast(token) {
                    if c.kind() == group_kind {
-                        visited.insert(c.clone());
+                        // regions are not real comments
-                        last = c;
+                        if c.text().trim().starts_with("// region:")
-                        continue;
+                            || c.text().trim().starts_with("// endregion")
+                        {
+                            break;
+                        } else {
+                            visited.insert(c.clone());
+                            last = c;
+                            continue;
+                        }
                    }
                }
                // The comment group ends because either:
@@ -224,6 +249,7 @@ mod tests {
                FoldKind::Mods => "mods",
                FoldKind::Block => "block",
                FoldKind::ArgList => "arglist",
+                FoldKind::Region => "region",
            };
            assert_eq!(kind, &attr.unwrap());
        }
@@ -418,4 +444,17 @@ fn foo<fold arglist>(
 "#,
        )
    }
+    #[test]
+    fn fold_region() {
+        check(
+            r#"
+// 1. some normal comment
+<fold region>// region: test
+// 2. some normal comment
+calling_function(x,y);
+// endregion: test</fold>
+"#,
+        )
+    }
 }
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index 9a605b09d..a9454cfa3 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -5,6 +5,7 @@ use hir::{
 use ide_db::{
    base_db::SourceDatabase,
    defs::{Definition, NameClass, NameRefClass},
+    helpers::FamousDefs,
    RootDatabase,
 };
 use itertools::Itertools;
@@ -107,16 +108,14 @@ pub(crate) fn hover(
        }
    };
    if let Some(definition) = definition {
-        if let Some(markup) = hover_for_definition(db, definition) {
+        let famous_defs = match &definition {
-            let markup = markup.as_str();
+            Definition::ModuleDef(ModuleDef::BuiltinType(_)) => {
-            let markup = if !markdown {
+                Some(FamousDefs(&sema, sema.scope(&node).krate()))
-                remove_markdown(markup)
+            }
-            } else if links_in_hover {
+            _ => None,
-                rewrite_links(db, markup, &definition)
+        };
-            } else {
+        if let Some(markup) = hover_for_definition(db, definition, famous_defs.as_ref()) {
-                remove_links(markup)
+            res.markup = process_markup(sema.db, definition, &markup, links_in_hover, markdown);
-            };
-            res.markup = Markup::from(markup);
            if let Some(action) = show_implementations_action(db, definition) {
                res.actions.push(action);
            }
@@ -138,6 +137,9 @@ pub(crate) fn hover(
        // don't highlight the entire parent node on comment hover
        return None;
    }
+    if let res @ Some(_) = hover_for_keyword(&sema, links_in_hover, markdown, &token) {
+        return res;
+    }
    let node = token
        .ancestors()
@@ -272,6 +274,24 @@ fn hover_markup(
    }
 }
+fn process_markup(
+    db: &RootDatabase,
+    def: Definition,
+    markup: &Markup,
+    links_in_hover: bool,
+    markdown: bool,
+) -> Markup {
+    let markup = markup.as_str();
+    let markup = if !markdown {
+        remove_markdown(markup)
+    } else if links_in_hover {
+        rewrite_links(db, markup, &def)
+    } else {
+        remove_links(markup)
+    };
+    Markup::from(markup)
+}
 fn definition_owner_name(db: &RootDatabase, def: &Definition) -> Option<String> {
    match def {
        Definition::Field(f) => Some(f.parent_def(db).name(db)),
@@ -304,7 +324,11 @@ fn definition_mod_path(db: &RootDatabase, def: &Definition) -> Option<String> {
    def.module(db).map(|module| render_path(db, module, definition_owner_name(db, def)))
 }
-fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
+fn hover_for_definition(
+    db: &RootDatabase,
+    def: Definition,
+    famous_defs: Option<&FamousDefs>,
+) -> Option<Markup> {
    let mod_path = definition_mod_path(db, &def);
    return match def {
        Definition::Macro(it) => {
@@ -339,7 +363,9 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
            ModuleDef::Static(it) => from_def_source(db, it, mod_path),
            ModuleDef::Trait(it) => from_def_source(db, it, mod_path),
            ModuleDef::TypeAlias(it) => from_def_source(db, it, mod_path),
-            ModuleDef::BuiltinType(it) => Some(Markup::fenced_block(&it.name())),
+            ModuleDef::BuiltinType(it) => famous_defs
+                .and_then(|fd| hover_for_builtin(fd, it))
+                .or_else(|| Some(Markup::fenced_block(&it.name()))),
        },
        Definition::Local(it) => Some(Markup::fenced_block(&it.ty(db).display(db))),
        Definition::SelfType(impl_def) => {
@@ -380,11 +406,52 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
    }
 }
+fn hover_for_keyword(
+    sema: &Semantics<RootDatabase>,
+    links_in_hover: bool,
+    markdown: bool,
+    token: &SyntaxToken,
+) -> Option<RangeInfo<HoverResult>> {
+    if !token.kind().is_keyword() {
+        return None;
+    }
+    let famous_defs = FamousDefs(&sema, sema.scope(&token.parent()).krate());
+    // std exposes {}_keyword modules with docstrings on the root to document keywords
+    let keyword_mod = format!("{}_keyword", token.text());
+    let doc_owner = find_std_module(&famous_defs, &keyword_mod)?;
+    let docs = doc_owner.attrs(sema.db).docs()?;
+    let markup = process_markup(
+        sema.db,
+        Definition::ModuleDef(doc_owner.into()),
+        &hover_markup(Some(docs.into()), Some(token.text().into()), None)?,
+        links_in_hover,
+        markdown,
+    );
+    Some(RangeInfo::new(token.text_range(), HoverResult { markup, actions: Default::default() }))
+}
+fn hover_for_builtin(famous_defs: &FamousDefs, builtin: hir::BuiltinType) -> Option<Markup> {
+    // std exposes prim_{} modules with docstrings on the root to document the builtins
+    let primitive_mod = format!("prim_{}", builtin.name());
+    let doc_owner = find_std_module(famous_defs, &primitive_mod)?;
+    let docs = doc_owner.attrs(famous_defs.0.db).docs()?;
+    hover_markup(Some(docs.into()), Some(builtin.name().to_string()), None)
+}
+fn find_std_module(famous_defs: &FamousDefs, name: &str) -> Option<hir::Module> {
+    let db = famous_defs.0.db;
+    let std_crate = famous_defs.std()?;
+    let std_root_module = std_crate.root_module(db);
+    std_root_module
+        .children(db)
+        .find(|module| module.name(db).map_or(false, |module| module.to_string() == name))
+}
 fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
    return tokens.max_by_key(priority);
    fn priority(n: &SyntaxToken) -> usize {
        match n.kind() {
-            IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] => 3,
+            IDENT | INT_NUMBER | LIFETIME_IDENT | T![self] | T![super] | T![crate] => 3,
            T!['('] | T![')'] => 2,
            kind if kind.is_trivia() => 0,
            _ => 1,
@@ -3496,4 +3563,75 @@ mod foo$0;
            "#]],
        );
    }
+    #[test]
+    fn hover_self_in_use() {
+        check(
+            r#"
+//! This should not appear
+mod foo {
+    /// But this should appear
+    pub mod bar {}
+}
+use foo::bar::{self$0};
+"#,
+            expect![[r#"
+                *self*
+                ```rust
+                test::foo
+                ```
+                ```rust
+                pub mod bar
+                ```
+                ---
+                But this should appear
+            "#]],
+        )
+    }
+    #[test]
+    fn hover_keyword() {
+        let ra_fixture = r#"//- /main.rs crate:main deps:std
+fn f() { retur$0n; }"#;
+        let fixture = format!("{}\n{}", ra_fixture, FamousDefs::FIXTURE);
+        check(
+            &fixture,
+            expect![[r#"
+                *return*
+                ```rust
+                return
+                ```
+                ---
+                Docs for return_keyword
+            "#]],
+        );
+    }
+    #[test]
+    fn hover_builtin() {
+        let ra_fixture = r#"//- /main.rs crate:main deps:std
+cosnt _: &str$0 = ""; }"#;
+        let fixture = format!("{}\n{}", ra_fixture, FamousDefs::FIXTURE);
+        check(
+            &fixture,
+            expect![[r#"
+                *str*
+                ```rust
+                str
+                ```
+                ---
+                Docs for prim_str
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/join_lines.rs b/crates/ide/src/join_lines.rs
index 2c077ed1f..7fcae13e0 100644
--- a/crates/ide/src/join_lines.rs
+++ b/crates/ide/src/join_lines.rs
@@ -7,6 +7,7 @@ use syntax::{
    SyntaxKind::{self, USE_TREE, WHITESPACE},
    SyntaxNode, SyntaxToken, TextRange, TextSize, T,
 };
+use test_utils::mark;
 use text_edit::{TextEdit, TextEditBuilder};
 // Feature: Join Lines
@@ -44,9 +45,9 @@ pub(crate) fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
        let text = token.text();
        for (pos, _) in text[range].bytes().enumerate().filter(|&(_, b)| b == b'\n') {
            let pos: TextSize = (pos as u32).into();
-            let off = token.text_range().start() + range.start() + pos;
+            let offset = token.text_range().start() + range.start() + pos;
-            if !edit.invalidates_offset(off) {
+            if !edit.invalidates_offset(offset) {
-                remove_newline(&mut edit, &token, off);
+                remove_newline(&mut edit, &token, offset);
            }
        }
    }
@@ -56,14 +57,25 @@ pub(crate) fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
 fn remove_newline(edit: &mut TextEditBuilder, token: &SyntaxToken, offset: TextSize) {
    if token.kind() != WHITESPACE || token.text().bytes().filter(|&b| b == b'\n').count() != 1 {
-        // The node is either the first or the last in the file
+        let mut string_open_quote = false;
-        let suff = &token.text()[TextRange::new(
+        if let Some(string) = ast::String::cast(token.clone()) {
-            offset - token.text_range().start() + TextSize::of('\n'),
+            if let Some(range) = string.open_quote_text_range() {
-            TextSize::of(token.text()),
+                mark::hit!(join_string_literal);
-        )];
+                string_open_quote = range.end() == offset;
-        let spaces = suff.bytes().take_while(|&b| b == b' ').count();
+            }
+        }
-        edit.replace(TextRange::at(offset, ((spaces + 1) as u32).into()), " ".to_string());
+        let n_spaces_after_line_break = {
+            let suff = &token.text()[TextRange::new(
+                offset - token.text_range().start() + TextSize::of('\n'),
+                TextSize::of(token.text()),
+            )];
+            suff.bytes().take_while(|&b| b == b' ').count()
+        };
+        let range = TextRange::at(offset, ((n_spaces_after_line_break + 1) as u32).into());
+        let replace_with = if string_open_quote { "" } else { " " };
+        edit.replace(range, replace_with.to_string());
        return;
    }
@@ -194,7 +206,7 @@ fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
 #[cfg(test)]
 mod tests {
    use syntax::SourceFile;
-    use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range};
+    use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range, mark};
    use super::*;
@@ -771,4 +783,42 @@ fn foo() {
        ",
        );
    }
+    #[test]
+    fn join_string_literal() {
+        mark::check!(join_string_literal);
+        check_join_lines(
+            r#"
+fn main() {
+    $0"
+hello
+";
+}
+"#,
+            r#"
+fn main() {
+    $0"hello
+";
+}
+"#,
+        );
+        check_join_lines(
+            r#"
+fn main() {
+    "
+$0hello
+world
+";
+}
+"#,
+            r#"
+fn main() {
+    "
+$0hello world
+";
+}
+"#,
+        );
+    }
 }
diff --git a/crates/ide/src/references/rename.rs b/crates/ide/src/references/rename.rs
index 22ddeeae3..1919639a3 100644
--- a/crates/ide/src/references/rename.rs
+++ b/crates/ide/src/references/rename.rs
@@ -88,6 +88,8 @@ pub(crate) fn rename_with_semantics(
    let def = find_definition(sema, syntax, position)?;
    match def {
        Definition::ModuleDef(ModuleDef::Module(module)) => rename_mod(&sema, module, new_name),
+        Definition::SelfType(_) => bail!("Cannot rename `Self`"),
+        Definition::ModuleDef(ModuleDef::BuiltinType(_)) => bail!("Cannot rename builtin type"),
        def => rename_reference(sema, def, new_name),
    }
 }
@@ -122,7 +124,7 @@ fn check_identifier(new_name: &str) -> RenameResult<IdentifierKind> {
                Ok(IdentifierKind::Lifetime)
            }
            (SyntaxKind::LIFETIME_IDENT, _) => {
-                bail!("Invalid name `{0}`: Cannot rename lifetime to {0}", new_name)
+                bail!("Invalid name `{}`: not a lifetime identifier", new_name)
            }
            (_, Some(syntax_error)) => bail!("Invalid name `{}`: {}", new_name, syntax_error),
            (_, None) => bail!("Invalid name `{}`: not an identifier", new_name),
@@ -162,119 +164,6 @@ fn find_definition(
    .ok_or_else(|| format_err!("No references found at position"))
 }
-fn source_edit_from_references(
-    _sema: &Semantics<RootDatabase>,
-    file_id: FileId,
-    references: &[FileReference],
-    def: Definition,
-    new_name: &str,
-) -> (FileId, TextEdit) {
-    let mut edit = TextEdit::builder();
-    for reference in references {
-        let (range, replacement) = match &reference.name {
-            // if the ranges differ then the node is inside a macro call, we can't really attempt
-            // to make special rewrites like shorthand syntax and such, so just rename the node in
-            // the macro input
-            ast::NameLike::NameRef(name_ref)
-                if name_ref.syntax().text_range() == reference.range =>
-            {
-                source_edit_from_name_ref(name_ref, new_name, def)
-            }
-            ast::NameLike::Name(name) if name.syntax().text_range() == reference.range => {
-                source_edit_from_name(name, new_name)
-            }
-            _ => None,
-        }
-        .unwrap_or_else(|| (reference.range, new_name.to_string()));
-        edit.replace(range, replacement);
-    }
-    (file_id, edit.finish())
-}
-fn source_edit_from_name(name: &ast::Name, new_name: &str) -> Option<(TextRange, String)> {
-    if let Some(_) = ast::RecordPatField::for_field_name(name) {
-        if let Some(ident_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
-            return Some((
-                TextRange::empty(ident_pat.syntax().text_range().start()),
-                format!("{}: ", new_name),
-            ));
-        }
-    }
-    None
-}
-fn source_edit_from_name_ref(
-    name_ref: &ast::NameRef,
-    new_name: &str,
-    def: Definition,
-) -> Option<(TextRange, String)> {
-    if let Some(record_field) = ast::RecordExprField::for_name_ref(name_ref) {
-        let rcf_name_ref = record_field.name_ref();
-        let rcf_expr = record_field.expr();
-        match (rcf_name_ref, rcf_expr.and_then(|it| it.name_ref())) {
-            // field: init-expr, check if we can use a field init shorthand
-            (Some(field_name), Some(init)) => {
-                if field_name == *name_ref {
-                    if init.text() == new_name {
-                        mark::hit!(test_rename_field_put_init_shorthand);
-                        // same names, we can use a shorthand here instead.
-                        // we do not want to erase attributes hence this range start
-                        let s = field_name.syntax().text_range().start();
-                        let e = record_field.syntax().text_range().end();
-                        return Some((TextRange::new(s, e), new_name.to_owned()));
-                    }
-                } else if init == *name_ref {
-                    if field_name.text() == new_name {
-                        mark::hit!(test_rename_local_put_init_shorthand);
-                        // same names, we can use a shorthand here instead.
-                        // we do not want to erase attributes hence this range start
-                        let s = field_name.syntax().text_range().start();
-                        let e = record_field.syntax().text_range().end();
-                        return Some((TextRange::new(s, e), new_name.to_owned()));
-                    }
-                }
-                None
-            }
-            // init shorthand
-            // FIXME: instead of splitting the shorthand, recursively trigger a rename of the
-            // other name https://github.com/rust-analyzer/rust-analyzer/issues/6547
-            (None, Some(_)) if matches!(def, Definition::Field(_)) => {
-                mark::hit!(test_rename_field_in_field_shorthand);
-                let s = name_ref.syntax().text_range().start();
-                Some((TextRange::empty(s), format!("{}: ", new_name)))
-            }
-            (None, Some(_)) if matches!(def, Definition::Local(_)) => {
-                mark::hit!(test_rename_local_in_field_shorthand);
-                let s = name_ref.syntax().text_range().end();
-                Some((TextRange::empty(s), format!(": {}", new_name)))
-            }
-            _ => None,
-        }
-    } else if let Some(record_field) = ast::RecordPatField::for_field_name_ref(name_ref) {
-        let rcf_name_ref = record_field.name_ref();
-        let rcf_pat = record_field.pat();
-        match (rcf_name_ref, rcf_pat) {
-            // field: rename
-            (Some(field_name), Some(ast::Pat::IdentPat(pat))) if field_name == *name_ref => {
-                // field name is being renamed
-                if pat.name().map_or(false, |it| it.text() == new_name) {
-                    mark::hit!(test_rename_field_put_init_shorthand_pat);
-                    // same names, we can use a shorthand here instead/
-                    // we do not want to erase attributes hence this range start
-                    let s = field_name.syntax().text_range().start();
-                    let e = record_field.syntax().text_range().end();
-                    Some((TextRange::new(s, e), pat.to_string()))
-                } else {
-                    None
-                }
-            }
-            _ => None,
-        }
-    } else {
-        None
-    }
-}
 fn rename_mod(
    sema: &Semantics<RootDatabase>,
    module: Module,
@@ -308,18 +197,75 @@ fn rename_mod(
                TextEdit::replace(name.syntax().text_range(), new_name.to_string()),
            ),
            _ => unreachable!(),
-        };
+        }
    }
    let def = Definition::ModuleDef(ModuleDef::Module(module));
    let usages = def.usages(sema).all();
    let ref_edits = usages.iter().map(|(&file_id, references)| {
-        source_edit_from_references(sema, file_id, references, def, new_name)
+        (file_id, source_edit_from_references(references, def, new_name))
    });
    source_change.extend(ref_edits);
    Ok(source_change)
 }
+fn rename_reference(
+    sema: &Semantics<RootDatabase>,
+    def: Definition,
+    new_name: &str,
+) -> RenameResult<SourceChange> {
+    let ident_kind = check_identifier(new_name)?;
+    let def_is_lbl_or_lt = matches!(
+        def,
+        Definition::GenericParam(hir::GenericParam::LifetimeParam(_)) | Definition::Label(_)
+    );
+    match (ident_kind, def) {
+        (IdentifierKind::ToSelf, _)
+        | (IdentifierKind::Underscore, _)
+        | (IdentifierKind::Ident, _)
+            if def_is_lbl_or_lt =>
+        {
+            mark::hit!(rename_not_a_lifetime_ident_ref);
+            bail!("Invalid name `{}`: not a lifetime identifier", new_name)
+        }
+        (IdentifierKind::Lifetime, _) if def_is_lbl_or_lt => mark::hit!(rename_lifetime),
+        (IdentifierKind::Lifetime, _) => {
+            mark::hit!(rename_not_an_ident_ref);
+            bail!("Invalid name `{}`: not an identifier", new_name)
+        }
+        (IdentifierKind::ToSelf, Definition::Local(local)) if local.is_self(sema.db) => {
+            // no-op
+            mark::hit!(rename_self_to_self);
+            return Ok(SourceChange::default());
+        }
+        (ident_kind, Definition::Local(local)) if local.is_self(sema.db) => {
+            mark::hit!(rename_self_to_param);
+            return rename_self_to_param(sema, local, new_name, ident_kind);
+        }
+        (IdentifierKind::ToSelf, Definition::Local(local)) => {
+            mark::hit!(rename_to_self);
+            return rename_to_self(sema, local);
+        }
+        (IdentifierKind::ToSelf, _) => bail!("Invalid name `{}`: not an identifier", new_name),
+        (IdentifierKind::Ident, _) | (IdentifierKind::Underscore, _) => mark::hit!(rename_ident),
+    }
+    let usages = def.usages(sema).all();
+    if !usages.is_empty() && ident_kind == IdentifierKind::Underscore {
+        mark::hit!(rename_underscore_multiple);
+        bail!("Cannot rename reference to `_` as it is being referenced multiple times");
+    }
+    let mut source_change = SourceChange::default();
+    source_change.extend(usages.iter().map(|(&file_id, references)| {
+        (file_id, source_edit_from_references(&references, def, new_name))
+    }));
+    let (file_id, edit) = source_edit_from_def(sema, def, new_name)?;
+    source_change.insert_source_edit(file_id, edit);
+    Ok(source_change)
+}
 fn rename_to_self(sema: &Semantics<RootDatabase>, local: hir::Local) -> RenameResult<SourceChange> {
    if never!(local.is_self(sema.db)) {
        bail!("rename_to_self invoked on self");
@@ -384,7 +330,7 @@ fn rename_to_self(sema: &Semantics<RootDatabase>, local: hir::Local) -> RenameRe
    let usages = def.usages(sema).all();
    let mut source_change = SourceChange::default();
    source_change.extend(usages.iter().map(|(&file_id, references)| {
-        source_edit_from_references(sema, file_id, references, def, "self")
+        (file_id, source_edit_from_references(references, def, "self"))
    }));
    source_change.insert_source_edit(
        file_id.original_file(sema.db),
@@ -394,29 +340,6 @@ fn rename_to_self(sema: &Semantics<RootDatabase>, local: hir::Local) -> RenameRe
    Ok(source_change)
 }
-fn text_edit_from_self_param(self_param: &ast::SelfParam, new_name: &str) -> Option<TextEdit> {
-    fn target_type_name(impl_def: &ast::Impl) -> Option<String> {
-        if let Some(ast::Type::PathType(p)) = impl_def.self_ty() {
-            return Some(p.path()?.segment()?.name_ref()?.text().to_string());
-        }
-        None
-    }
-    let impl_def = self_param.syntax().ancestors().find_map(|it| ast::Impl::cast(it))?;
-    let type_name = target_type_name(&impl_def)?;
-    let mut replacement_text = String::from(new_name);
-    replacement_text.push_str(": ");
-    match (self_param.amp_token(), self_param.mut_token()) {
-        (None, None) => (),
-        (Some(_), None) => replacement_text.push('&'),
-        (_, Some(_)) => replacement_text.push_str("&mut "),
-    };
-    replacement_text.push_str(type_name.as_str());
-    Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
-}
 fn rename_self_to_param(
    sema: &Semantics<RootDatabase>,
    local: hir::Local,
@@ -441,66 +364,143 @@ fn rename_self_to_param(
    let mut source_change = SourceChange::default();
    source_change.insert_source_edit(file_id.original_file(sema.db), edit);
    source_change.extend(usages.iter().map(|(&file_id, references)| {
-        source_edit_from_references(sema, file_id, &references, def, new_name)
+        (file_id, source_edit_from_references(&references, def, new_name))
    }));
    Ok(source_change)
 }
-fn rename_reference(
+fn text_edit_from_self_param(self_param: &ast::SelfParam, new_name: &str) -> Option<TextEdit> {
-    sema: &Semantics<RootDatabase>,
+    fn target_type_name(impl_def: &ast::Impl) -> Option<String> {
+        if let Some(ast::Type::PathType(p)) = impl_def.self_ty() {
+            return Some(p.path()?.segment()?.name_ref()?.text().to_string());
+        }
+        None
+    }
+    let impl_def = self_param.syntax().ancestors().find_map(|it| ast::Impl::cast(it))?;
+    let type_name = target_type_name(&impl_def)?;
+    let mut replacement_text = String::from(new_name);
+    replacement_text.push_str(": ");
+    match (self_param.amp_token(), self_param.mut_token()) {
+        (Some(_), None) => replacement_text.push('&'),
+        (Some(_), Some(_)) => replacement_text.push_str("&mut "),
+        (_, _) => (),
+    };
+    replacement_text.push_str(type_name.as_str());
+    Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
+}
+fn source_edit_from_references(
+    references: &[FileReference],
    def: Definition,
    new_name: &str,
-) -> RenameResult<SourceChange> {
+) -> TextEdit {
-    let ident_kind = check_identifier(new_name)?;
+    let mut edit = TextEdit::builder();
+    for reference in references {
-    let def_is_lbl_or_lt = matches!(
+        let (range, replacement) = match &reference.name {
-        def,
+            // if the ranges differ then the node is inside a macro call, we can't really attempt
-        Definition::GenericParam(hir::GenericParam::LifetimeParam(_)) | Definition::Label(_)
+            // to make special rewrites like shorthand syntax and such, so just rename the node in
-    );
+            // the macro input
-    match (ident_kind, def) {
+            ast::NameLike::NameRef(name_ref)
-        (IdentifierKind::ToSelf, _)
+                if name_ref.syntax().text_range() == reference.range =>
-        | (IdentifierKind::Underscore, _)
+            {
-        | (IdentifierKind::Ident, _)
+                source_edit_from_name_ref(name_ref, new_name, def)
-            if def_is_lbl_or_lt =>
+            }
-        {
+            ast::NameLike::Name(name) if name.syntax().text_range() == reference.range => {
-            mark::hit!(rename_not_a_lifetime_ident_ref);
+                source_edit_from_name(name, new_name)
-            bail!("Invalid name `{}`: not a lifetime identifier", new_name)
+            }
-        }
+            _ => None,
-        (IdentifierKind::Lifetime, _) if def_is_lbl_or_lt => mark::hit!(rename_lifetime),
-        (IdentifierKind::Lifetime, _) => {
-            mark::hit!(rename_not_an_ident_ref);
-            bail!("Invalid name `{}`: not an identifier", new_name)
-        }
-        (IdentifierKind::ToSelf, Definition::Local(local)) if local.is_self(sema.db) => {
-            // no-op
-            mark::hit!(rename_self_to_self);
-            return Ok(SourceChange::default());
-        }
-        (ident_kind, Definition::Local(local)) if local.is_self(sema.db) => {
-            mark::hit!(rename_self_to_param);
-            return rename_self_to_param(sema, local, new_name, ident_kind);
-        }
-        (IdentifierKind::ToSelf, Definition::Local(local)) => {
-            mark::hit!(rename_to_self);
-            return rename_to_self(sema, local);
        }
-        (IdentifierKind::ToSelf, _) => bail!("Invalid name `{}`: not an identifier", new_name),
+        .unwrap_or_else(|| (reference.range, new_name.to_string()));
-        (IdentifierKind::Ident, _) | (IdentifierKind::Underscore, _) => mark::hit!(rename_ident),
+        edit.replace(range, replacement);
    }
+    edit.finish()
+}
-    let usages = def.usages(sema).all();
+fn source_edit_from_name(name: &ast::Name, new_name: &str) -> Option<(TextRange, String)> {
-    if !usages.is_empty() && ident_kind == IdentifierKind::Underscore {
+    if let Some(_) = ast::RecordPatField::for_field_name(name) {
-        mark::hit!(rename_underscore_multiple);
+        if let Some(ident_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
-        bail!("Cannot rename reference to `_` as it is being referenced multiple times");
+            return Some((
+                TextRange::empty(ident_pat.syntax().text_range().start()),
+                [new_name, ": "].concat(),
+            ));
+        }
    }
-    let mut source_change = SourceChange::default();
+    None
-    source_change.extend(usages.iter().map(|(&file_id, references)| {
+}
-        source_edit_from_references(sema, file_id, &references, def, new_name)
-    }));
-    let (file_id, edit) = source_edit_from_def(sema, def, new_name)?;
+fn source_edit_from_name_ref(
-    source_change.insert_source_edit(file_id, edit);
+    name_ref: &ast::NameRef,
-    Ok(source_change)
+    new_name: &str,
+    def: Definition,
+) -> Option<(TextRange, String)> {
+    if let Some(record_field) = ast::RecordExprField::for_name_ref(name_ref) {
+        let rcf_name_ref = record_field.name_ref();
+        let rcf_expr = record_field.expr();
+        match (rcf_name_ref, rcf_expr.and_then(|it| it.name_ref())) {
+            // field: init-expr, check if we can use a field init shorthand
+            (Some(field_name), Some(init)) => {
+                if field_name == *name_ref {
+                    if init.text() == new_name {
+                        mark::hit!(test_rename_field_put_init_shorthand);
+                        // same names, we can use a shorthand here instead.
+                        // we do not want to erase attributes hence this range start
+                        let s = field_name.syntax().text_range().start();
+                        let e = record_field.syntax().text_range().end();
+                        return Some((TextRange::new(s, e), new_name.to_owned()));
+                    }
+                } else if init == *name_ref {
+                    if field_name.text() == new_name {
+                        mark::hit!(test_rename_local_put_init_shorthand);
+                        // same names, we can use a shorthand here instead.
+                        // we do not want to erase attributes hence this range start
+                        let s = field_name.syntax().text_range().start();
+                        let e = record_field.syntax().text_range().end();
+                        return Some((TextRange::new(s, e), new_name.to_owned()));
+                    }
+                }
+                None
+            }
+            // init shorthand
+            // FIXME: instead of splitting the shorthand, recursively trigger a rename of the
+            // other name https://github.com/rust-analyzer/rust-analyzer/issues/6547
+            (None, Some(_)) if matches!(def, Definition::Field(_)) => {
+                mark::hit!(test_rename_field_in_field_shorthand);
+                let s = name_ref.syntax().text_range().start();
+                Some((TextRange::empty(s), format!("{}: ", new_name)))
+            }
+            (None, Some(_)) if matches!(def, Definition::Local(_)) => {
+                mark::hit!(test_rename_local_in_field_shorthand);
+                let s = name_ref.syntax().text_range().end();
+                Some((TextRange::empty(s), format!(": {}", new_name)))
+            }
+            _ => None,
+        }
+    } else if let Some(record_field) = ast::RecordPatField::for_field_name_ref(name_ref) {
+        let rcf_name_ref = record_field.name_ref();
+        let rcf_pat = record_field.pat();
+        match (rcf_name_ref, rcf_pat) {
+            // field: rename
+            (Some(field_name), Some(ast::Pat::IdentPat(pat))) if field_name == *name_ref => {
+                // field name is being renamed
+                if pat.name().map_or(false, |it| it.text() == new_name) {
+                    mark::hit!(test_rename_field_put_init_shorthand_pat);
+                    // same names, we can use a shorthand here instead/
+                    // we do not want to erase attributes hence this range start
+                    let s = field_name.syntax().text_range().start();
+                    let e = record_field.syntax().text_range().end();
+                    Some((TextRange::new(s, e), pat.to_string()))
+                } else {
+                    None
+                }
+            }
+            _ => None,
+        }
+    } else {
+        None
+    }
 }
 fn source_edit_from_def(
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index 1e7baed20..65f60891e 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -189,7 +189,7 @@ pub(crate) fn doc_owner_to_def(
 ) -> Option<Definition> {
    let res: hir::ModuleDef = match_ast! {
        match item {
-            ast::SourceFile(it) => sema.scope(&item).module()?.into(),
+            ast::SourceFile(_it) => sema.scope(&item).module()?.into(),
            ast::Fn(it) => sema.to_def(&it)?.into(),
            ast::Struct(it) => sema.to_def(&it)?.into(),
            ast::Enum(it) => sema.to_def(&it)?.into(),
diff --git a/crates/ide_assists/src/handlers/add_turbo_fish.rs b/crates/ide_assists/src/handlers/add_turbo_fish.rs
index 8e9ea4fad..a08b55ebb 100644
--- a/crates/ide_assists/src/handlers/add_turbo_fish.rs
+++ b/crates/ide_assists/src/handlers/add_turbo_fish.rs
@@ -31,6 +31,7 @@ pub(crate) fn add_turbo_fish(acc: &mut Assists, ctx: &AssistContext) -> Option<(
            return None;
        }
        mark::hit!(add_turbo_fish_after_call);
+        mark::hit!(add_type_ascription_after_call);
        arg_list.l_paren_token()?.prev_token().filter(|it| it.kind() == SyntaxKind::IDENT)
    })?;
    let next_token = ident.next_token()?;
@@ -52,6 +53,24 @@ pub(crate) fn add_turbo_fish(acc: &mut Assists, ctx: &AssistContext) -> Option<(
        mark::hit!(add_turbo_fish_non_generic);
        return None;
    }
+    if let Some(let_stmt) = ctx.find_node_at_offset::<ast::LetStmt>() {
+        if let_stmt.colon_token().is_none() {
+            let type_pos = let_stmt.pat()?.syntax().last_token()?.text_range().end();
+            acc.add(
+                AssistId("add_type_ascription", AssistKind::RefactorRewrite),
+                "Add `: _` before assignment operator",
+                ident.text_range(),
+                |builder| match ctx.config.snippet_cap {
+                    Some(cap) => builder.insert_snippet(cap, type_pos, ": ${0:_}"),
+                    None => builder.insert(type_pos, ": _"),
+                },
+            )?
+        } else {
+            mark::hit!(add_type_ascription_already_typed);
+        }
+    }
    acc.add(
        AssistId("add_turbo_fish", AssistKind::RefactorRewrite),
        "Add `::<>`",
@@ -65,7 +84,7 @@ pub(crate) fn add_turbo_fish(acc: &mut Assists, ctx: &AssistContext) -> Option<(
 #[cfg(test)]
 mod tests {
-    use crate::tests::{check_assist, check_assist_not_applicable};
+    use crate::tests::{check_assist, check_assist_by_label, check_assist_not_applicable};
    use super::*;
    use test_utils::mark;
@@ -161,4 +180,91 @@ fn main() {
 "#,
        );
    }
+    #[test]
+    fn add_type_ascription_function() {
+        check_assist_by_label(
+            add_turbo_fish,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x = make$0();
+}
+"#,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x: ${0:_} = make();
+}
+"#,
+            "Add `: _` before assignment operator",
+        );
+    }
+    #[test]
+    fn add_type_ascription_after_call() {
+        mark::check!(add_type_ascription_after_call);
+        check_assist_by_label(
+            add_turbo_fish,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x = make()$0;
+}
+"#,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x: ${0:_} = make();
+}
+"#,
+            "Add `: _` before assignment operator",
+        );
+    }
+    #[test]
+    fn add_type_ascription_method() {
+        check_assist_by_label(
+            add_turbo_fish,
+            r#"
+struct S;
+impl S {
+    fn make<T>(&self) -> T {}
+}
+fn main() {
+    let x = S.make$0();
+}
+"#,
+            r#"
+struct S;
+impl S {
+    fn make<T>(&self) -> T {}
+}
+fn main() {
+    let x: ${0:_} = S.make();
+}
+"#,
+            "Add `: _` before assignment operator",
+        );
+    }
+    #[test]
+    fn add_type_ascription_already_typed() {
+        mark::check!(add_type_ascription_already_typed);
+        check_assist(
+            add_turbo_fish,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x: () = make$0();
+}
+"#,
+            r#"
+fn make<T>() -> T {}
+fn main() {
+    let x: () = make::<${0:_}>();
+}
+"#,
+        );
+    }
 }
diff --git a/crates/ide_assists/src/handlers/apply_demorgan.rs b/crates/ide_assists/src/handlers/apply_demorgan.rs
index 6997ea048..128b1eb56 100644
--- a/crates/ide_assists/src/handlers/apply_demorgan.rs
+++ b/crates/ide_assists/src/handlers/apply_demorgan.rs
@@ -1,4 +1,5 @@
 use syntax::ast::{self, AstNode};
+use test_utils::mark;
 use crate::{utils::invert_boolean_expression, AssistContext, AssistId, AssistKind, Assists};
@@ -43,9 +44,36 @@ pub(crate) fn apply_demorgan(acc: &mut Assists, ctx: &AssistContext) -> Option<(
        "Apply De Morgan's law",
        op_range,
        |edit| {
+            let paren_expr = expr.syntax().parent().and_then(|parent| ast::ParenExpr::cast(parent));
+            let neg_expr = paren_expr
+                .clone()
+                .and_then(|paren_expr| paren_expr.syntax().parent())
+                .and_then(|parent| ast::PrefixExpr::cast(parent))
+                .and_then(|prefix_expr| {
+                    if prefix_expr.op_kind().unwrap() == ast::PrefixOp::Not {
+                        Some(prefix_expr)
+                    } else {
+                        None
+                    }
+                });
            edit.replace(op_range, opposite_op);
-            edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text()));
-            edit.replace(rhs_range, format!("{})", not_rhs.syntax().text()));
+            if let Some(paren_expr) = paren_expr {
+                edit.replace(lhs_range, not_lhs.syntax().text());
+                edit.replace(rhs_range, not_rhs.syntax().text());
+                if let Some(neg_expr) = neg_expr {
+                    mark::hit!(demorgan_double_negation);
+                    edit.replace(neg_expr.op_token().unwrap().text_range(), "");
+                } else {
+                    mark::hit!(demorgan_double_parens);
+                    edit.replace(paren_expr.l_paren_token().unwrap().text_range(), "!(");
+                }
+            } else {
+                edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text()));
+                edit.replace(rhs_range, format!("{})", not_rhs.syntax().text()));
+            }
        },
    )
 }
@@ -62,6 +90,7 @@ fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
 #[cfg(test)]
 mod tests {
    use ide_db::helpers::FamousDefs;
+    use test_utils::mark;
    use super::*;
@@ -156,4 +185,16 @@ fn f() {
    fn demorgan_doesnt_apply_with_cursor_not_on_op() {
        check_assist_not_applicable(apply_demorgan, "fn f() { $0 !x || !x }")
    }
+    #[test]
+    fn demorgan_doesnt_double_negation() {
+        mark::check!(demorgan_double_negation);
+        check_assist(apply_demorgan, "fn f() { !(x ||$0 x) }", "fn f() { (!x && !x) }")
+    }
+    #[test]
+    fn demorgan_doesnt_double_parens() {
+        mark::check!(demorgan_double_parens);
+        check_assist(apply_demorgan, "fn f() { (x ||$0 x) }", "fn f() { !(!x && !x) }")
+    }
 }
diff --git a/crates/ide_assists/src/handlers/convert_comment_block.rs b/crates/ide_assists/src/handlers/convert_comment_block.rs
new file mode 100644
index 000000000..cdc45fc42
--- /dev/null
+++ b/crates/ide_assists/src/handlers/convert_comment_block.rs
@@ -0,0 +1,419 @@
+use itertools::Itertools;
+use std::convert::identity;
+use syntax::{
+    ast::{
+        self,
+        edit::IndentLevel,
+        Comment, CommentKind,
+        CommentPlacement::{Inner, Outer},
+        CommentShape::{self, Block, Line},
+        Whitespace,
+    },
+    AstToken, Direction, SyntaxElement, TextRange,
+};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+/// Assist: line_to_block
+///
+/// Converts comments between block and single-line form
+///
+/// ```
+///    // Multi-line
+///    // comment
+/// ```
+/// ->
+/// ```
+///   /**
+///   Multi-line
+///   comment
+///   */
+/// ```
+pub(crate) fn convert_comment_block(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    if let Some(comment) = ctx.find_token_at_offset::<ast::Comment>() {
+        // Only allow comments which are alone on their line
+        if let Some(prev) = comment.syntax().prev_token() {
+            if Whitespace::cast(prev).filter(|w| w.text().contains('\n')).is_none() {
+                return None;
+            }
+        }
+        return match comment.kind().shape {
+            ast::CommentShape::Block => block_to_line(acc, comment),
+            ast::CommentShape::Line => line_to_block(acc, comment),
+        };
+    }
+    return None;
+}
+fn block_to_line(acc: &mut Assists, comment: ast::Comment) -> Option<()> {
+    let target = comment.syntax().text_range();
+    acc.add(
+        AssistId("block_to_line", AssistKind::RefactorRewrite),
+        "Replace block comment with line comments",
+        target,
+        |edit| {
+            let indentation = IndentLevel::from_token(comment.syntax());
+            let line_prefix =
+                comment_kind_prefix(CommentKind { shape: CommentShape::Line, ..comment.kind() });
+            let text = comment.text();
+            let text = &text[comment.prefix().len()..(text.len() - "*/".len())].trim();
+            let lines = text.lines().peekable();
+            let indent_spaces = indentation.to_string();
+            let output = lines
+                .map(|l| l.trim_start_matches(&indent_spaces))
+                .map(|l| {
+                    // Don't introduce trailing whitespace
+                    if l.is_empty() {
+                        line_prefix.to_string()
+                    } else {
+                        format!("{} {}", line_prefix, l.trim_start_matches(&indent_spaces))
+                    }
+                })
+                .join(&format!("\n{}", indent_spaces));
+            edit.replace(target, output)
+        },
+    )
+}
+fn line_to_block(acc: &mut Assists, comment: ast::Comment) -> Option<()> {
+    // Find all the comments we'll be collapsing into a block
+    let comments = relevant_line_comments(&comment);
+    // Establish the target of our edit based on the comments we found
+    let target = TextRange::new(
+        comments[0].syntax().text_range().start(),
+        comments.last().unwrap().syntax().text_range().end(),
+    );
+    acc.add(
+        AssistId("line_to_block", AssistKind::RefactorRewrite),
+        "Replace line comments with a single block comment",
+        target,
+        |edit| {
+            // We pick a single indentation level for the whole block comment based on the
+            // comment where the assist was invoked. This will be prepended to the
+            // contents of each line comment when they're put into the block comment.
+            let indentation = IndentLevel::from_token(&comment.syntax());
+            let block_comment_body =
+                comments.into_iter().map(|c| line_comment_text(indentation, c)).join("\n");
+            let block_prefix =
+                comment_kind_prefix(CommentKind { shape: CommentShape::Block, ..comment.kind() });
+            let output =
+                format!("{}\n{}\n{}*/", block_prefix, block_comment_body, indentation.to_string());
+            edit.replace(target, output)
+        },
+    )
+}
+/// The line -> block assist can  be invoked from anywhere within a sequence of line comments.
+/// relevant_line_comments crawls backwards and forwards finding the complete sequence of comments that will
+/// be joined.
+fn relevant_line_comments(comment: &ast::Comment) -> Vec<Comment> {
+    // The prefix identifies the kind of comment we're dealing with
+    let prefix = comment.prefix();
+    let same_prefix = |c: &ast::Comment| c.prefix() == prefix;
+    // These tokens are allowed to exist between comments
+    let skippable = |not: &SyntaxElement| {
+        not.clone()
+            .into_token()
+            .and_then(Whitespace::cast)
+            .map(|w| !w.spans_multiple_lines())
+            .unwrap_or(false)
+    };
+    // Find all preceding comments (in reverse order) that have the same prefix
+    let prev_comments = comment
+        .syntax()
+        .siblings_with_tokens(Direction::Prev)
+        .filter(|s| !skippable(s))
+        .map(|not| not.into_token().and_then(Comment::cast).filter(same_prefix))
+        .take_while(|opt_com| opt_com.is_some())
+        .filter_map(identity)
+        .skip(1); // skip the first element so we don't duplicate it in next_comments
+    let next_comments = comment
+        .syntax()
+        .siblings_with_tokens(Direction::Next)
+        .filter(|s| !skippable(s))
+        .map(|not| not.into_token().and_then(Comment::cast).filter(same_prefix))
+        .take_while(|opt_com| opt_com.is_some())
+        .filter_map(identity);
+    let mut comments: Vec<_> = prev_comments.collect();
+    comments.reverse();
+    comments.extend(next_comments);
+    comments
+}
+// Line comments usually begin with a single space character following the prefix as seen here:
+//^
+// But comments can also include indented text:
+//    > Hello there
+//
+// We handle this by stripping *AT MOST* one space character from the start of the line
+// This has its own problems because it can cause alignment issues:
+//
+//              /*
+// a      ----> a
+//b       ----> b
+//              */
+//
+// But since such comments aren't idiomatic we're okay with this.
+fn line_comment_text(indentation: IndentLevel, comm: ast::Comment) -> String {
+    let contents_without_prefix = comm.text().strip_prefix(comm.prefix()).unwrap();
+    let contents = contents_without_prefix.strip_prefix(' ').unwrap_or(contents_without_prefix);
+    // Don't add the indentation if the line is empty
+    if contents.is_empty() {
+        contents.to_owned()
+    } else {
+        indentation.to_string() + &contents
+    }
+}
+fn comment_kind_prefix(ck: ast::CommentKind) -> &'static str {
+    match (ck.shape, ck.doc) {
+        (Line, Some(Inner)) => "//!",
+        (Line, Some(Outer)) => "///",
+        (Line, None) => "//",
+        (Block, Some(Inner)) => "/*!",
+        (Block, Some(Outer)) => "/**",
+        (Block, None) => "/*",
+    }
+}
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+    use super::*;
+    #[test]
+    fn single_line_to_block() {
+        check_assist(
+            convert_comment_block,
+            r#"
+// line$0 comment
+fn main() {
+    foo();
+}
+"#,
+            r#"
+/*
+line comment
+*/
+fn main() {
+    foo();
+}
+"#,
+        );
+    }
+    #[test]
+    fn single_line_to_block_indented() {
+        check_assist(
+            convert_comment_block,
+            r#"
+fn main() {
+    // line$0 comment
+    foo();
+}
+"#,
+            r#"
+fn main() {
+    /*
+    line comment
+    */
+    foo();
+}
+"#,
+        );
+    }
+    #[test]
+    fn multiline_to_block() {
+        check_assist(
+            convert_comment_block,
+            r#"
+fn main() {
+    // above
+    // line$0 comment
+    //
+    // below
+    foo();
+}
+"#,
+            r#"
+fn main() {
+    /*
+    above
+    line comment
+    below
+    */
+    foo();
+}
+"#,
+        );
+    }
+    #[test]
+    fn end_of_line_to_block() {
+        check_assist_not_applicable(
+            convert_comment_block,
+            r#"
+fn main() {
+    foo(); // end-of-line$0 comment
+}
+"#,
+        );
+    }
+    #[test]
+    fn single_line_different_kinds() {
+        check_assist(
+            convert_comment_block,
+            r#"
+fn main() {
+    /// different prefix
+    // line$0 comment
+    // below
+    foo();
+}
+"#,
+            r#"
+fn main() {
+    /// different prefix
+    /*
+    line comment
+    below
+    */
+    foo();
+}
+"#,
+        );
+    }
+    #[test]
+    fn single_line_separate_chunks() {
+        check_assist(
+            convert_comment_block,
+            r#"
+fn main() {
+    // different chunk
+    // line$0 comment
+    // below
+    foo();
+}
+"#,
+            r#"
+fn main() {
+    // different chunk
+    /*
+    line comment
+    below
+    */
+    foo();
+}
+"#,
+        );
+    }
+    #[test]
+    fn doc_block_comment_to_lines() {
+        check_assist(
+            convert_comment_block,
+            r#"
+/**
+ hi$0 there
+*/
+"#,
+            r#"
+/// hi there
+"#,
+        );
+    }
+    #[test]
+    fn block_comment_to_lines() {
+        check_assist(
+            convert_comment_block,
+            r#"
+/*
+ hi$0 there
+*/
+"#,
+            r#"
+// hi there
+"#,
+        );
+    }
+    #[test]
+    fn inner_doc_block_to_lines() {
+        check_assist(
+            convert_comment_block,
+            r#"
+/*!
+ hi$0 there
+*/
+"#,
+            r#"
+//! hi there
+"#,
+        );
+    }
+    #[test]
+    fn block_to_lines_indent() {
+        check_assist(
+            convert_comment_block,
+            r#"
+fn main() {
+    /*!
+    hi$0 there
+    ```
+      code_sample
+    ```
+    */
+}
+"#,
+            r#"
+fn main() {
+    //! hi there
+    //!
+    //! ```
+    //!   code_sample
+    //! ```
+}
+"#,
+        );
+    }
+    #[test]
+    fn end_of_line_block_to_line() {
+        check_assist_not_applicable(
+            convert_comment_block,
+            r#"
+fn main() {
+    foo(); /* end-of-line$0 comment */
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide_assists/src/handlers/extract_variable.rs b/crates/ide_assists/src/handlers/extract_variable.rs
index 98f3dc6ca..312ac7ac4 100644
--- a/crates/ide_assists/src/handlers/extract_variable.rs
+++ b/crates/ide_assists/src/handlers/extract_variable.rs
@@ -8,7 +8,7 @@ use syntax::{
 };
 use test_utils::mark;
-use crate::{AssistContext, AssistId, AssistKind, Assists};
+use crate::{utils::suggest_name, AssistContext, AssistId, AssistKind, Assists};
 // Assist: extract_variable
 //
@@ -54,7 +54,7 @@ pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option
            let var_name = match &field_shorthand {
                Some(it) => it.to_string(),
-                None => "var_name".to_string(),
+                None => suggest_name::variable(&to_extract, &ctx.sema),
            };
            let expr_range = match &field_shorthand {
                Some(it) => it.syntax().text_range().cover(to_extract.syntax().text_range()),
@@ -274,8 +274,8 @@ fn foo() {
 "#,
            r#"
 fn foo() {
-    let $0var_name = bar(1 + 1);
+    let $0bar = bar(1 + 1);
-    var_name
+    bar
 }
 "#,
        )
@@ -401,8 +401,8 @@ fn main() {
 ",
            "
 fn main() {
-    let $0var_name = bar.foo();
+    let $0foo = bar.foo();
-    let v = var_name;
+    let v = foo;
 }
 ",
        );
@@ -557,6 +557,202 @@ fn main() {
    }
    #[test]
+    fn extract_var_name_from_type() {
+        check_assist(
+            extract_variable,
+            r#"
+struct Test(i32);
+fn foo() -> Test {
+    $0{ Test(10) }$0
+}
+"#,
+            r#"
+struct Test(i32);
+fn foo() -> Test {
+    let $0test = { Test(10) };
+    test
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_name_from_parameter() {
+        check_assist(
+            extract_variable,
+            r#"
+fn bar(test: u32, size: u32)
+fn foo() {
+    bar(1, $01+1$0);
+}
+"#,
+            r#"
+fn bar(test: u32, size: u32)
+fn foo() {
+    let $0size = 1+1;
+    bar(1, size);
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_parameter_name_has_precedence_over_type() {
+        check_assist(
+            extract_variable,
+            r#"
+struct TextSize(u32);
+fn bar(test: u32, size: TextSize)
+fn foo() {
+    bar(1, $0{ TextSize(1+1) }$0);
+}
+"#,
+            r#"
+struct TextSize(u32);
+fn bar(test: u32, size: TextSize)
+fn foo() {
+    let $0size = { TextSize(1+1) };
+    bar(1, size);
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_name_from_function() {
+        check_assist(
+            extract_variable,
+            r#"
+fn is_required(test: u32, size: u32) -> bool
+fn foo() -> bool {
+    $0is_required(1, 2)$0
+}
+"#,
+            r#"
+fn is_required(test: u32, size: u32) -> bool
+fn foo() -> bool {
+    let $0is_required = is_required(1, 2);
+    is_required
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_name_from_method() {
+        check_assist(
+            extract_variable,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32) -> u32 { n }
+}
+fn foo() -> u32 {
+    $0S.bar(1)$0
+}
+"#,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32) -> u32 { n }
+}
+fn foo() -> u32 {
+    let $0bar = S.bar(1);
+    bar
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_name_from_method_param() {
+        check_assist(
+            extract_variable,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32, size: u32) { n }
+}
+fn foo() {
+    S.bar($01 + 1$0, 2)
+}
+"#,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32, size: u32) { n }
+}
+fn foo() {
+    let $0n = 1 + 1;
+    S.bar(n, 2)
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_name_from_ufcs_method_param() {
+        check_assist(
+            extract_variable,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32, size: u32) { n }
+}
+fn foo() {
+    S::bar(&S, $01 + 1$0, 2)
+}
+"#,
+            r#"
+struct S;
+impl S {
+    fn bar(&self, n: u32, size: u32) { n }
+}
+fn foo() {
+    let $0n = 1 + 1;
+    S::bar(&S, n, 2)
+}
+"#,
+        )
+    }
+    #[test]
+    fn extract_var_parameter_name_has_precedence_over_function() {
+        check_assist(
+            extract_variable,
+            r#"
+fn bar(test: u32, size: u32)
+fn foo() {
+    bar(1, $0symbol_size(1, 2)$0);
+}
+"#,
+            r#"
+fn bar(test: u32, size: u32)
+fn foo() {
+    let $0size = symbol_size(1, 2);
+    bar(1, size);
+}
+"#,
+        )
+    }
+    #[test]
    fn test_extract_var_for_return_not_applicable() {
        check_assist_not_applicable(extract_variable, "fn foo() { $0return$0; } ");
    }
diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index 53542d433..9c8148462 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -115,6 +115,7 @@ mod handlers {
    mod auto_import;
    mod change_visibility;
    mod convert_integer_literal;
+    mod convert_comment_block;
    mod early_return;
    mod expand_glob_import;
    mod extract_function;
@@ -178,6 +179,7 @@ mod handlers {
            auto_import::auto_import,
            change_visibility::change_visibility,
            convert_integer_literal::convert_integer_literal,
+            convert_comment_block::convert_comment_block,
            early_return::convert_to_guarded_return,
            expand_glob_import::expand_glob_import,
            extract_struct_from_enum_variant::extract_struct_from_enum_variant,
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index 880ab6fe3..62f959082 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -1,5 +1,7 @@
 //! Assorted functions shared by several assists.
+pub(crate) mod suggest_name;
 use std::ops;
 use ast::TypeBoundsOwner;
diff --git a/crates/ide_assists/src/utils/suggest_name.rs b/crates/ide_assists/src/utils/suggest_name.rs
new file mode 100644
index 000000000..533624c1f
--- /dev/null
+++ b/crates/ide_assists/src/utils/suggest_name.rs
@@ -0,0 +1,729 @@
+//! This module contains functions to suggest names for expressions, functions and other items
+use hir::Semantics;
+use ide_db::RootDatabase;
+use itertools::Itertools;
+use stdx::to_lower_snake_case;
+use syntax::{
+    ast::{self, NameOwner},
+    match_ast, AstNode,
+};
+/// Trait names, that will be ignored when in `impl Trait` and `dyn Trait`
+const USELESS_TRAITS: &[&str] = &["Send", "Sync", "Copy", "Clone", "Eq", "PartialEq"];
+/// Identifier names that won't be suggested, ever
+///
+/// **NOTE**: they all must be snake lower case
+const USELESS_NAMES: &[&str] =
+    &["new", "default", "option", "some", "none", "ok", "err", "str", "string"];
+/// Generic types replaced by their first argument
+///
+/// # Examples
+/// `Option<Name>` -> `Name`
+/// `Result<User, Error>` -> `User`
+const WRAPPER_TYPES: &[&str] = &["Box", "Option", "Result"];
+/// Prefixes to strip from methods names
+///
+/// # Examples
+/// `vec.as_slice()` -> `slice`
+/// `args.into_config()` -> `config`
+/// `bytes.to_vec()` -> `vec`
+const USELESS_METHOD_PREFIXES: &[&str] = &["into_", "as_", "to_"];
+/// Useless methods that are stripped from expression
+///
+/// # Examples
+/// `var.name().to_string()` -> `var.name()`
+const USELESS_METHODS: &[&str] = &[
+    "to_string",
+    "as_str",
+    "to_owned",
+    "as_ref",
+    "clone",
+    "cloned",
+    "expect",
+    "expect_none",
+    "unwrap",
+    "unwrap_none",
+    "unwrap_or",
+    "unwrap_or_default",
+    "unwrap_or_else",
+    "unwrap_unchecked",
+    "iter",
+    "into_iter",
+    "iter_mut",
+];
+/// Suggest name of variable for given expression
+///
+/// **NOTE**: it is caller's responsibility to guarantee uniqueness of the name.
+/// I.e. it doesn't look for names in scope.
+///
+/// # Current implementation
+///
+/// In current implementation, the function tries to get the name from
+/// the following sources:
+///
+/// * if expr is an argument to function/method, use paramter name
+/// * if expr is a function/method call, use function name
+/// * expression type name if it exists (E.g. `()`, `fn() -> ()` or `!` do not have names)
+/// * fallback: `var_name`
+///
+/// It also applies heuristics to filter out less informative names
+///
+/// Currently it sticks to the first name found.
+pub(crate) fn variable(expr: &ast::Expr, sema: &Semantics<'_, RootDatabase>) -> String {
+    // `from_param` does not benifit from stripping
+    // it need the largest context possible
+    // so we check firstmost
+    if let Some(name) = from_param(expr, sema) {
+        return name;
+    }
+    let mut next_expr = Some(expr.clone());
+    while let Some(expr) = next_expr {
+        let name = from_call(&expr).or_else(|| from_type(&expr, sema));
+        if let Some(name) = name {
+            return name;
+        }
+        match expr {
+            ast::Expr::RefExpr(inner) => next_expr = inner.expr(),
+            ast::Expr::BoxExpr(inner) => next_expr = inner.expr(),
+            ast::Expr::AwaitExpr(inner) => next_expr = inner.expr(),
+            // ast::Expr::BlockExpr(block) => expr = block.tail_expr(),
+            ast::Expr::CastExpr(inner) => next_expr = inner.expr(),
+            ast::Expr::MethodCallExpr(method) if is_useless_method(&method) => {
+                next_expr = method.receiver();
+            }
+            ast::Expr::ParenExpr(inner) => next_expr = inner.expr(),
+            ast::Expr::TryExpr(inner) => next_expr = inner.expr(),
+            ast::Expr::PrefixExpr(prefix) if prefix.op_kind() == Some(ast::PrefixOp::Deref) => {
+                next_expr = prefix.expr()
+            }
+            _ => break,
+        }
+    }
+    "var_name".to_string()
+}
+fn normalize(name: &str) -> Option<String> {
+    let name = to_lower_snake_case(name);
+    if USELESS_NAMES.contains(&name.as_str()) {
+        return None;
+    }
+    if !is_valid_name(&name) {
+        return None;
+    }
+    Some(name)
+}
+fn is_valid_name(name: &str) -> bool {
+    match syntax::lex_single_syntax_kind(name) {
+        Some((syntax::SyntaxKind::IDENT, _error)) => true,
+        _ => false,
+    }
+}
+fn is_useless_method(method: &ast::MethodCallExpr) -> bool {
+    let ident = method.name_ref().and_then(|it| it.ident_token());
+    if let Some(ident) = ident {
+        USELESS_METHODS.contains(&ident.text())
+    } else {
+        false
+    }
+}
+fn from_call(expr: &ast::Expr) -> Option<String> {
+    from_func_call(expr).or_else(|| from_method_call(expr))
+}
+fn from_func_call(expr: &ast::Expr) -> Option<String> {
+    let call = match expr {
+        ast::Expr::CallExpr(call) => call,
+        _ => return None,
+    };
+    let func = match call.expr()? {
+        ast::Expr::PathExpr(path) => path,
+        _ => return None,
+    };
+    let ident = func.path()?.segment()?.name_ref()?.ident_token()?;
+    normalize(ident.text())
+}
+fn from_method_call(expr: &ast::Expr) -> Option<String> {
+    let method = match expr {
+        ast::Expr::MethodCallExpr(call) => call,
+        _ => return None,
+    };
+    let ident = method.name_ref()?.ident_token()?;
+    let mut name = ident.text();
+    if USELESS_METHODS.contains(&name) {
+        return None;
+    }
+    for prefix in USELESS_METHOD_PREFIXES {
+        if let Some(suffix) = name.strip_prefix(prefix) {
+            name = suffix;
+            break;
+        }
+    }
+    normalize(&name)
+}
+fn from_param(expr: &ast::Expr, sema: &Semantics<'_, RootDatabase>) -> Option<String> {
+    let arg_list = expr.syntax().parent().and_then(ast::ArgList::cast)?;
+    let args_parent = arg_list.syntax().parent()?;
+    let func = match_ast! {
+        match args_parent {
+            ast::CallExpr(call) => {
+                let func = call.expr()?;
+                let func_ty = sema.type_of_expr(&func)?;
+                func_ty.as_callable(sema.db)?
+            },
+            ast::MethodCallExpr(method) => sema.resolve_method_call_as_callable(&method)?,
+            _ => return None,
+        }
+    };
+    let (idx, _) = arg_list.args().find_position(|it| it == expr).unwrap();
+    let (pat, _) = func.params(sema.db).into_iter().nth(idx)?;
+    let pat = match pat? {
+        either::Either::Right(pat) => pat,
+        _ => return None,
+    };
+    let name = var_name_from_pat(&pat)?;
+    normalize(&name.to_string())
+}
+fn var_name_from_pat(pat: &ast::Pat) -> Option<ast::Name> {
+    match pat {
+        ast::Pat::IdentPat(var) => var.name(),
+        ast::Pat::RefPat(ref_pat) => var_name_from_pat(&ref_pat.pat()?),
+        ast::Pat::BoxPat(box_pat) => var_name_from_pat(&box_pat.pat()?),
+        _ => None,
+    }
+}
+fn from_type(expr: &ast::Expr, sema: &Semantics<'_, RootDatabase>) -> Option<String> {
+    let ty = sema.type_of_expr(expr)?;
+    let ty = ty.remove_ref().unwrap_or(ty);
+    name_of_type(&ty, sema.db)
+}
+fn name_of_type(ty: &hir::Type, db: &RootDatabase) -> Option<String> {
+    let name = if let Some(adt) = ty.as_adt() {
+        let name = adt.name(db).to_string();
+        if WRAPPER_TYPES.contains(&name.as_str()) {
+            let inner_ty = ty.type_parameters().next()?;
+            return name_of_type(&inner_ty, db);
+        }
+        name
+    } else if let Some(trait_) = ty.as_dyn_trait() {
+        trait_name(&trait_, db)?
+    } else if let Some(traits) = ty.as_impl_traits(db) {
+        let mut iter = traits.into_iter().filter_map(|t| trait_name(&t, db));
+        let name = iter.next()?;
+        if iter.next().is_some() {
+            return None;
+        }
+        name
+    } else {
+        return None;
+    };
+    normalize(&name)
+}
+fn trait_name(trait_: &hir::Trait, db: &RootDatabase) -> Option<String> {
+    let name = trait_.name(db).to_string();
+    if USELESS_TRAITS.contains(&name.as_str()) {
+        return None;
+    }
+    Some(name)
+}
+#[cfg(test)]
+mod tests {
+    use ide_db::base_db::{fixture::WithFixture, FileRange};
+    use super::*;
+    #[track_caller]
+    fn check(ra_fixture: &str, expected: &str) {
+        let (db, file_id, range_or_offset) = RootDatabase::with_range_or_offset(ra_fixture);
+        let frange = FileRange { file_id, range: range_or_offset.into() };
+        let sema = Semantics::new(&db);
+        let source_file = sema.parse(frange.file_id);
+        let element = source_file.syntax().covering_element(frange.range);
+        let expr =
+            element.ancestors().find_map(ast::Expr::cast).expect("selection is not an expression");
+        assert_eq!(
+            expr.syntax().text_range(),
+            frange.range,
+            "selection is not an expression(yet contained in one)"
+        );
+        let name = variable(&expr, &sema);
+        assert_eq!(&name, expected);
+    }
+    #[test]
+    fn no_args() {
+        check(r#"fn foo() { $0bar()$0 }"#, "bar");
+        check(r#"fn foo() { $0bar.frobnicate()$0 }"#, "frobnicate");
+    }
+    #[test]
+    fn single_arg() {
+        check(r#"fn foo() { $0bar(1)$0 }"#, "bar");
+    }
+    #[test]
+    fn many_args() {
+        check(r#"fn foo() { $0bar(1, 2, 3)$0 }"#, "bar");
+    }
+    #[test]
+    fn path() {
+        check(r#"fn foo() { $0i32::bar(1, 2, 3)$0 }"#, "bar");
+    }
+    #[test]
+    fn generic_params() {
+        check(r#"fn foo() { $0bar::<i32>(1, 2, 3)$0 }"#, "bar");
+        check(r#"fn foo() { $0bar.frobnicate::<i32, u32>()$0 }"#, "frobnicate");
+    }
+    #[test]
+    fn to_name() {
+        check(
+            r#"
+struct Args;
+struct Config;
+impl Args {
+    fn to_config(&self) -> Config {}
+}
+fn foo() {
+    $0Args.to_config()$0;
+}
+"#,
+            "config",
+        );
+    }
+    #[test]
+    fn plain_func() {
+        check(
+            r#"
+fn bar(n: i32, m: u32);
+fn foo() { bar($01$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn mut_param() {
+        check(
+            r#"
+fn bar(mut n: i32, m: u32);
+fn foo() { bar($01$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn func_does_not_exist() {
+        check(r#"fn foo() { bar($01$0, 2) }"#, "var_name");
+    }
+    #[test]
+    fn unnamed_param() {
+        check(
+            r#"
+fn bar(_: i32, m: u32);
+fn foo() { bar($01$0, 2) }
+"#,
+            "var_name",
+        );
+    }
+    #[test]
+    fn tuple_pat() {
+        check(
+            r#"
+fn bar((n, k): (i32, i32), m: u32);
+fn foo() {
+    bar($0(1, 2)$0, 3)
+}
+"#,
+            "var_name",
+        );
+    }
+    #[test]
+    fn ref_pat() {
+        check(
+            r#"
+fn bar(&n: &i32, m: u32);
+fn foo() { bar($0&1$0, 3) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn box_pat() {
+        check(
+            r#"
+fn bar(box n: &i32, m: u32);
+fn foo() { bar($01$0, 3) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn param_out_of_index() {
+        check(
+            r#"
+fn bar(n: i32, m: u32);
+fn foo() { bar(1, 2, $03$0) }
+"#,
+            "var_name",
+        );
+    }
+    #[test]
+    fn generic_param_resolved() {
+        check(
+            r#"
+fn bar<T>(n: T, m: u32);
+fn foo() { bar($01$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn generic_param_unresolved() {
+        check(
+            r#"
+fn bar<T>(n: T, m: u32);
+fn foo<T>(x: T) { bar($0x$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn method() {
+        check(
+            r#"
+struct S;
+impl S { fn bar(&self, n: i32, m: u32); }
+fn foo() { S.bar($01$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn method_ufcs() {
+        check(
+            r#"
+struct S;
+impl S { fn bar(&self, n: i32, m: u32); }
+fn foo() { S::bar(&S, $01$0, 2) }
+"#,
+            "n",
+        );
+    }
+    #[test]
+    fn method_self() {
+        check(
+            r#"
+struct S;
+impl S { fn bar(&self, n: i32, m: u32); }
+fn foo() { S::bar($0&S$0, 1, 2) }
+"#,
+            "s",
+        );
+    }
+    #[test]
+    fn method_self_named() {
+        check(
+            r#"
+struct S;
+impl S { fn bar(strukt: &Self, n: i32, m: u32); }
+fn foo() { S::bar($0&S$0, 1, 2) }
+"#,
+            "strukt",
+        );
+    }
+    #[test]
+    fn i32() {
+        check(r#"fn foo() { let _: i32 = $01$0; }"#, "var_name");
+    }
+    #[test]
+    fn u64() {
+        check(r#"fn foo() { let _: u64 = $01$0; }"#, "var_name");
+    }
+    #[test]
+    fn bool() {
+        check(r#"fn foo() { let _: bool = $0true$0; }"#, "var_name");
+    }
+    #[test]
+    fn struct_unit() {
+        check(
+            r#"
+struct Seed;
+fn foo() { let _ = $0Seed$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn struct_unit_to_snake() {
+        check(
+            r#"
+struct SeedState;
+fn foo() { let _ = $0SeedState$0; }
+"#,
+            "seed_state",
+        );
+    }
+    #[test]
+    fn struct_single_arg() {
+        check(
+            r#"
+struct Seed(u32);
+fn foo() { let _ = $0Seed(0)$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn struct_with_fields() {
+        check(
+            r#"
+struct Seed { value: u32 }
+fn foo() { let _ = $0Seed { value: 0 }$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn enum_() {
+        check(
+            r#"
+enum Kind { A, B }
+fn foo() { let _ = $0Kind::A$0; }
+"#,
+            "kind",
+        );
+    }
+    #[test]
+    fn enum_generic_resolved() {
+        check(
+            r#"
+enum Kind<T> { A { x: T }, B }
+fn foo() { let _ = $0Kind::A { x:1 }$0; }
+"#,
+            "kind",
+        );
+    }
+    #[test]
+    fn enum_generic_unresolved() {
+        check(
+            r#"
+enum Kind<T> { A { x: T }, B }
+fn foo<T>(x: T) { let _ = $0Kind::A { x }$0; }
+"#,
+            "kind",
+        );
+    }
+    #[test]
+    fn dyn_trait() {
+        check(
+            r#"
+trait DynHandler {}
+fn bar() -> dyn DynHandler {}
+fn foo() { $0(bar())$0; }
+"#,
+            "dyn_handler",
+        );
+    }
+    #[test]
+    fn impl_trait() {
+        check(
+            r#"
+trait StaticHandler {}
+fn bar() -> impl StaticHandler {}
+fn foo() { $0(bar())$0; }
+"#,
+            "static_handler",
+        );
+    }
+    #[test]
+    fn impl_trait_plus_clone() {
+        check(
+            r#"
+trait StaticHandler {}
+trait Clone {}
+fn bar() -> impl StaticHandler + Clone {}
+fn foo() { $0(bar())$0; }
+"#,
+            "static_handler",
+        );
+    }
+    #[test]
+    fn impl_trait_plus_lifetime() {
+        check(
+            r#"
+trait StaticHandler {}
+trait Clone {}
+fn bar<'a>(&'a i32) -> impl StaticHandler + 'a {}
+fn foo() { $0(bar(&1))$0; }
+"#,
+            "static_handler",
+        );
+    }
+    #[test]
+    fn impl_trait_plus_trait() {
+        check(
+            r#"
+trait Handler {}
+trait StaticHandler {}
+fn bar() -> impl StaticHandler + Handler {}
+fn foo() { $0(bar())$0; }
+"#,
+            "bar",
+        );
+    }
+    #[test]
+    fn ref_value() {
+        check(
+            r#"
+struct Seed;
+fn bar() -> &Seed {}
+fn foo() { $0(bar())$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn box_value() {
+        check(
+            r#"
+struct Box<T>(*const T);
+struct Seed;
+fn bar() -> Box<Seed> {}
+fn foo() { $0(bar())$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn box_generic() {
+        check(
+            r#"
+struct Box<T>(*const T);
+fn bar<T>() -> Box<T> {}
+fn foo<T>() { $0(bar::<T>())$0; }
+"#,
+            "bar",
+        );
+    }
+    #[test]
+    fn option_value() {
+        check(
+            r#"
+enum Option<T> { Some(T) }
+struct Seed;
+fn bar() -> Option<Seed> {}
+fn foo() { $0(bar())$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn result_value() {
+        check(
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+struct Seed;
+struct Error;
+fn bar() -> Result<Seed, Error> {}
+fn foo() { $0(bar())$0; }
+"#,
+            "seed",
+        );
+    }
+    #[test]
+    fn ref_call() {
+        check(
+            r#"
+fn foo() { $0&bar(1, 3)$0 }
+"#,
+            "bar",
+        );
+    }
+    #[test]
+    fn name_to_string() {
+        check(
+            r#"
+fn foo() { $0function.name().to_string()$0 }
+"#,
+            "name",
+        );
+    }
+    #[test]
+    fn nested_useless_method() {
+        check(
+            r#"
+fn foo() { $0function.name().as_ref().unwrap().to_string()$0 }
+"#,
+            "name",
+        );
+    }
+}
diff --git a/crates/ide_completion/src/completions/attribute.rs b/crates/ide_completion/src/completions/attribute.rs
index 3a5bc4381..cb05e85fc 100644
--- a/crates/ide_completion/src/completions/attribute.rs
+++ b/crates/ide_completion/src/completions/attribute.rs
@@ -39,7 +39,8 @@ pub(crate) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext)
 }
 fn complete_attribute_start(acc: &mut Completions, ctx: &CompletionContext, attribute: &ast::Attr) {
-    for attr_completion in ATTRIBUTES {
+    let is_inner = attribute.kind() == ast::AttrKind::Inner;
+    for attr_completion in ATTRIBUTES.iter().filter(|compl| is_inner || !compl.prefer_inner) {
        let mut item = CompletionItem::new(
            CompletionKind::Attribute,
            ctx.source_range(),
diff --git a/crates/ide_completion/src/completions/fn_param.rs b/crates/ide_completion/src/completions/fn_param.rs
index 38e33a93e..1bcc8727f 100644
--- a/crates/ide_completion/src/completions/fn_param.rs
+++ b/crates/ide_completion/src/completions/fn_param.rs
@@ -25,9 +25,12 @@ pub(crate) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
            return;
        }
        func.param_list().into_iter().flat_map(|it| it.params()).for_each(|param| {
-            let text = param.syntax().text().to_string();
+            if let Some(pat) = param.pat() {
-            params.entry(text).or_insert(param);
+                let text = param.syntax().text().to_string();
-        })
+                let lookup = pat.syntax().text().to_string();
+                params.entry(text).or_insert(lookup);
+            }
+        });
    };
    for node in ctx.token.parent().ancestors() {
@@ -50,18 +53,12 @@ pub(crate) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
        };
    }
-    params
+    params.into_iter().for_each(|(label, lookup)| {
-        .into_iter()
+        CompletionItem::new(CompletionKind::Magic, ctx.source_range(), label)
-        .filter_map(|(label, param)| {
+            .kind(CompletionItemKind::Binding)
-            let lookup = param.pat()?.syntax().text().to_string();
+            .lookup_by(lookup)
-            Some((label, lookup))
+            .add_to(acc)
-        })
+    });
-        .for_each(|(label, lookup)| {
-            CompletionItem::new(CompletionKind::Magic, ctx.source_range(), label)
-                .kind(CompletionItemKind::Binding)
-                .lookup_by(lookup)
-                .add_to(acc)
-        });
 }
 #[cfg(test)]
diff --git a/crates/ide_completion/src/completions/keyword.rs b/crates/ide_completion/src/completions/keyword.rs
index eb81f9765..03c6dd454 100644
--- a/crates/ide_completion/src/completions/keyword.rs
+++ b/crates/ide_completion/src/completions/keyword.rs
@@ -1,5 +1,7 @@
 //! Completes keywords.
+use std::iter;
 use syntax::SyntaxKind;
 use test_utils::mark;
@@ -19,10 +21,14 @@ pub(crate) fn complete_use_tree_keyword(acc: &mut Completions, ctx: &CompletionC
        CompletionItem::new(CompletionKind::Keyword, source_range, "self")
            .kind(CompletionItemKind::Keyword)
            .add_to(acc);
-        CompletionItem::new(CompletionKind::Keyword, source_range, "super::")
+        if iter::successors(ctx.path_qual.clone(), |p| p.qualifier())
-            .kind(CompletionItemKind::Keyword)
+            .all(|p| p.segment().and_then(|s| s.super_token()).is_some())
-            .insert_text("super::")
+        {
-            .add_to(acc);
+            CompletionItem::new(CompletionKind::Keyword, source_range, "super::")
+                .kind(CompletionItemKind::Keyword)
+                .insert_text("super::")
+                .add_to(acc);
+        }
    }
    // Suggest .await syntax for types that implement Future trait
@@ -85,6 +91,7 @@ pub(crate) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionConte
    if ctx.is_expr {
        add_keyword(ctx, acc, "match", "match $0 {}");
        add_keyword(ctx, acc, "while", "while $0 {}");
+        add_keyword(ctx, acc, "while let", "while let $1 = $0 {}");
        add_keyword(ctx, acc, "loop", "loop {$0}");
        add_keyword(ctx, acc, "if", "if $0 {}");
        add_keyword(ctx, acc, "if let", "if let $1 = $0 {}");
@@ -204,9 +211,17 @@ mod tests {
            "#]],
        );
+        // FIXME: `self` shouldn't be shown here and the check below
        check(
            r"use a::$0",
            expect![[r#"
+            kw self
+        "#]],
+        );
+        check(
+            r"use super::$0",
+            expect![[r#"
                kw self
                kw super::
            "#]],
@@ -215,9 +230,8 @@ mod tests {
        check(
            r"use a::{b, $0}",
            expect![[r#"
-                kw self
+            kw self
-                kw super::
+        "#]],
-            "#]],
        );
    }
@@ -256,6 +270,7 @@ mod tests {
                kw trait
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -283,6 +298,7 @@ mod tests {
                kw trait
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -310,6 +326,7 @@ mod tests {
                kw trait
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -344,6 +361,7 @@ fn quux() -> i32 {
            expect![[r#"
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -393,6 +411,7 @@ fn quux() -> i32 {
                kw trait
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -552,6 +571,7 @@ pub mod future {
            expect![[r#"
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
@@ -611,6 +631,7 @@ fn foo() {
            expect![[r#"
                kw match
                kw while
+                kw while let
                kw loop
                kw if
                kw if let
diff --git a/crates/ide_completion/src/completions/qualified_path.rs b/crates/ide_completion/src/completions/qualified_path.rs
index 2afa6979e..72fb757b1 100644
--- a/crates/ide_completion/src/completions/qualified_path.rs
+++ b/crates/ide_completion/src/completions/qualified_path.rs
@@ -81,9 +81,7 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                        return None;
                    }
                    match item {
-                        hir::AssocItem::Function(func) => {
+                        hir::AssocItem::Function(func) => acc.add_function(ctx, func, None),
-                            acc.add_function(ctx, func, None);
-                        }
                        hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
                        hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
                    }
@@ -110,9 +108,7 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                    continue;
                }
                match item {
-                    hir::AssocItem::Function(func) => {
+                    hir::AssocItem::Function(func) => acc.add_function(ctx, func, None),
-                        acc.add_function(ctx, func, None);
-                    }
                    hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
                    hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
                }
@@ -143,9 +139,7 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                    // them.
                    if seen.insert(item) {
                        match item {
-                            hir::AssocItem::Function(func) => {
+                            hir::AssocItem::Function(func) => acc.add_function(ctx, func, None),
-                                acc.add_function(ctx, func, None);
-                            }
                            hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
                            hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
                        }
diff --git a/crates/ide_db/src/helpers.rs b/crates/ide_db/src/helpers.rs
index f9de8ce0e..3ff77400b 100644
--- a/crates/ide_db/src/helpers.rs
+++ b/crates/ide_db/src/helpers.rs
@@ -41,6 +41,10 @@ pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Cr
 impl FamousDefs<'_, '_> {
    pub const FIXTURE: &'static str = include_str!("helpers/famous_defs_fixture.rs");
+    pub fn std(&self) -> Option<Crate> {
+        self.find_crate("std")
+    }
    pub fn core(&self) -> Option<Crate> {
        self.find_crate("core")
    }
diff --git a/crates/ide_db/src/helpers/famous_defs_fixture.rs b/crates/ide_db/src/helpers/famous_defs_fixture.rs
index bb4e9666b..d3464ae17 100644
--- a/crates/ide_db/src/helpers/famous_defs_fixture.rs
+++ b/crates/ide_db/src/helpers/famous_defs_fixture.rs
@@ -129,3 +129,11 @@ pub mod prelude {
 }
 #[prelude_import]
 pub use prelude::*;
+//- /libstd.rs crate:std deps:core
+//! Signatures of traits, types and functions from the std lib for use in tests.
+/// Docs for return_keyword
+mod return_keyword {}
+/// Docs for prim_str
+mod prim_str {}
diff --git a/crates/mbe/Cargo.toml b/crates/mbe/Cargo.toml
index bbee2e32c..bb2656a80 100644
--- a/crates/mbe/Cargo.toml
+++ b/crates/mbe/Cargo.toml
@@ -18,9 +18,7 @@ syntax = { path = "../syntax", version = "0.0.0" }
 parser = { path = "../parser", version = "0.0.0" }
 tt = { path = "../tt", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
+stdx = { path = "../stdx", version = "0.0.0" }
-# FIXME: Paper over a bug in cargo-worspaces which block publishing
+[dev-dependencies]
-# https://github.com/pksunkara/cargo-workspaces/issues/39
+profile = { path = "../profile" }
-# [dev-dependencies]
-profile = { path = "../profile", version = "0.0.0" }
diff --git a/crates/mbe/src/benchmark.rs b/crates/mbe/src/benchmark.rs
index 6d81be880..503ad1355 100644
--- a/crates/mbe/src/benchmark.rs
+++ b/crates/mbe/src/benchmark.rs
@@ -40,18 +40,12 @@ fn benchmark_expand_macro_rules() {
            .into_iter()
            .map(|(id, tt)| {
                let res = rules[&id].expand(&tt);
-                if res.err.is_some() {
+                assert!(res.err.is_none());
-                    // FIXME:
-                    // Currently `invocation_fixtures` will generate some correct invocations but
-                    // cannot be expanded by mbe. We ignore errors here.
-                    // See: https://github.com/rust-analyzer/rust-analyzer/issues/4777
-                    eprintln!("err from {} {:?}", id, res.err);
-                }
                res.value.token_trees.len()
            })
            .sum()
    };
-    assert_eq!(hash, 66995);
+    assert_eq!(hash, 69413);
 }
 fn macro_rules_fixtures() -> FxHashMap<String, MacroRules> {
@@ -77,7 +71,7 @@ fn macro_rules_fixtures_tt() -> FxHashMap<String, tt::Subtree> {
        .collect()
 }
-// Generate random invocation fixtures from rules
+/// Generate random invocation fixtures from rules
 fn invocation_fixtures(rules: &FxHashMap<String, MacroRules>) -> Vec<(String, tt::Subtree)> {
    let mut seed = 123456789;
    let mut res = Vec::new();
@@ -86,11 +80,31 @@ fn invocation_fixtures(rules: &FxHashMap<String, MacroRules>) -> Vec<(String, tt
        for rule in &it.rules {
            // Generate twice
            for _ in 0..2 {
-                let mut subtree = tt::Subtree::default();
+                // The input are generated by filling the `Op` randomly.
-                for op in rule.lhs.iter() {
+                // However, there are some cases generated are ambiguous for expanding, for example:
-                    collect_from_op(op, &mut subtree, &mut seed);
+                // ```rust
+                // macro_rules! m {
+                //    ($($t:ident),* as $ty:ident) => {}
+                // }
+                // m!(as u32);  // error: local ambiguity: multiple parsing options: built-in NTs ident ('t') or 1 other option.
+                // ```
+                //
+                // So we just skip any error cases and try again
+                let mut try_cnt = 0;
+                loop {
+                    let mut subtree = tt::Subtree::default();
+                    for op in rule.lhs.iter() {
+                        collect_from_op(op, &mut subtree, &mut seed);
+                    }
+                    if it.expand(&subtree).err.is_none() {
+                        res.push((name.clone(), subtree));
+                        break;
+                    }
+                    try_cnt += 1;
+                    if try_cnt > 100 {
+                        panic!("invocaton fixture {} cannot be generated.\n", name);
+                    }
                }
-                res.push((name.clone(), subtree));
            }
        }
    }
diff --git a/crates/mbe/src/expander.rs b/crates/mbe/src/expander.rs
index e7e14b3cc..2efff8f52 100644
--- a/crates/mbe/src/expander.rs
+++ b/crates/mbe/src/expander.rs
@@ -5,7 +5,7 @@
 mod matcher;
 mod transcriber;
-use rustc_hash::FxHashMap;
+use smallvec::SmallVec;
 use syntax::SmolStr;
 use crate::{ExpandError, ExpandResult};
@@ -28,10 +28,10 @@ pub(crate) fn expand_rules(
                return ExpandResult::ok(value);
            }
        }
-        // Use the rule if we matched more tokens, or had fewer errors
+        // Use the rule if we matched more tokens, or bound variables count
        if let Some((prev_match, _)) = &match_ {
-            if (new_match.unmatched_tts, new_match.err_count)
+            if (new_match.unmatched_tts, -(new_match.bound_count as i32))
-                < (prev_match.unmatched_tts, prev_match.err_count)
+                < (prev_match.unmatched_tts, -(prev_match.bound_count as i32))
            {
                match_ = Some((new_match, rule));
            }
@@ -94,19 +94,19 @@ pub(crate) fn expand_rules(
 /// In other words, `Bindings` is a *multi* mapping from `SmolStr` to
 /// `tt::TokenTree`, where the index to select a particular `TokenTree` among
 /// many is not a plain `usize`, but an `&[usize]`.
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Clone, PartialEq, Eq)]
 struct Bindings {
-    inner: FxHashMap<SmolStr, Binding>,
+    inner: SmallVec<[(SmolStr, Binding); 4]>,
 }
-#[derive(Debug)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 enum Binding {
    Fragment(Fragment),
    Nested(Vec<Binding>),
    Empty,
 }
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 enum Fragment {
    /// token fragments are just copy-pasted into the output
    Tokens(tt::TokenTree),
diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs
index e3bd4c09a..9d3d28055 100644
--- a/crates/mbe/src/expander/matcher.rs
+++ b/crates/mbe/src/expander/matcher.rs
@@ -1,14 +1,74 @@
-//! FIXME: write short doc here
+//! An NFA-based parser, which is porting from rustc mbe parsing code
+//!
+//! See https://github.com/rust-lang/rust/blob/70b18bc2cbac4712020019f5bf57c00905373205/compiler/rustc_expand/src/mbe/macro_parser.rs
+//! Here is a quick intro to how the parser works, copied from rustc:
+//!
+//! A 'position' is a dot in the middle of a matcher, usually represented as a
+//! dot. For example `· a $( a )* a b` is a position, as is `a $( · a )* a b`.
+//!
+//! The parser walks through the input a character at a time, maintaining a list
+//! of threads consistent with the current position in the input string: `cur_items`.
+//!
+//! As it processes them, it fills up `eof_items` with threads that would be valid if
+//! the macro invocation is now over, `bb_items` with threads that are waiting on
+//! a Rust non-terminal like `$e:expr`, and `next_items` with threads that are waiting
+//! on a particular token. Most of the logic concerns moving the · through the
+//! repetitions indicated by Kleene stars. The rules for moving the · without
+//! consuming any input are called epsilon transitions. It only advances or calls
+//! out to the real Rust parser when no `cur_items` threads remain.
+//!
+//! Example:
+//!
+//! ```text, ignore
+//! Start parsing a a a a b against [· a $( a )* a b].
+//!
+//! Remaining input: a a a a b
+//! next: [· a $( a )* a b]
+//!
+//! - - - Advance over an a. - - -
+//!
+//! Remaining input: a a a b
+//! cur: [a · $( a )* a b]
+//! Descend/Skip (first item).
+//! next: [a $( · a )* a b]  [a $( a )* · a b].
+//!
+//! - - - Advance over an a. - - -
+//!
+//! Remaining input: a a b
+//! cur: [a $( a · )* a b]  [a $( a )* a · b]
+//! Follow epsilon transition: Finish/Repeat (first item)
+//! next: [a $( a )* · a b]  [a $( · a )* a b]  [a $( a )* a · b]
+//!
+//! - - - Advance over an a. - - - (this looks exactly like the last step)
+//!
+//! Remaining input: a b
+//! cur: [a $( a · )* a b]  [a $( a )* a · b]
+//! Follow epsilon transition: Finish/Repeat (first item)
+//! next: [a $( a )* · a b]  [a $( · a )* a b]  [a $( a )* a · b]
+//!
+//! - - - Advance over an a. - - - (this looks exactly like the last step)
+//!
+//! Remaining input: b
+//! cur: [a $( a · )* a b]  [a $( a )* a · b]
+//! Follow epsilon transition: Finish/Repeat (first item)
+//! next: [a $( a )* · a b]  [a $( · a )* a b]  [a $( a )* a · b]
+//!
+//! - - - Advance over a b. - - -
+//!
+//! Remaining input: ''
+//! eof: [a $( a )* a b ·]
+//! ```
 use crate::{
    expander::{Binding, Bindings, Fragment},
-    parser::{Op, RepeatKind, Separator},
+    parser::{Op, OpDelimited, OpDelimitedIter, RepeatKind, Separator},
    tt_iter::TtIter,
    ExpandError, MetaTemplate,
 };
 use super::ExpandResult;
 use parser::FragmentKind::*;
+use smallvec::{smallvec, SmallVec};
 use syntax::SmolStr;
 impl Bindings {
@@ -16,19 +76,19 @@ impl Bindings {
        // FIXME: Do we have a better way to represent an empty token ?
        // Insert an empty subtree for empty token
        let tt = tt::Subtree::default().into();
-        self.inner.insert(name.clone(), Binding::Fragment(Fragment::Tokens(tt)));
+        self.inner.push((name.clone(), Binding::Fragment(Fragment::Tokens(tt))));
    }
    fn push_empty(&mut self, name: &SmolStr) {
-        self.inner.insert(name.clone(), Binding::Empty);
+        self.inner.push((name.clone(), Binding::Empty));
    }
    fn push_nested(&mut self, idx: usize, nested: Bindings) -> Result<(), ExpandError> {
        for (key, value) in nested.inner {
-            if !self.inner.contains_key(&key) {
+            if self.get_mut(&key).is_none() {
-                self.inner.insert(key.clone(), Binding::Nested(Vec::new()));
+                self.inner.push((key.clone(), Binding::Nested(Vec::new())));
            }
-            match self.inner.get_mut(&key) {
+            match self.get_mut(&key) {
                Some(Binding::Nested(it)) => {
                    // insert empty nested bindings before this one
                    while it.len() < idx {
@@ -46,6 +106,14 @@ impl Bindings {
        }
        Ok(())
    }
+    fn get_mut(&mut self, name: &str) -> Option<&mut Binding> {
+        self.inner.iter_mut().find_map(|(n, b)| if n == name { Some(b) } else { None })
+    }
+    fn bindings(&self) -> impl Iterator<Item = &Binding> {
+        self.inner.iter().map(|(_, b)| b)
+    }
 }
 macro_rules! err {
@@ -57,7 +125,7 @@ macro_rules! err {
    };
 }
-#[derive(Debug, Default)]
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub(super) struct Match {
    pub(super) bindings: Bindings,
    /// We currently just keep the first error and count the rest to compare matches.
@@ -65,6 +133,8 @@ pub(super) struct Match {
    pub(super) err_count: usize,
    /// How many top-level token trees were left to match.
    pub(super) unmatched_tts: usize,
+    /// The number of bound variables
+    pub(super) bound_count: usize,
 }
 impl Match {
@@ -76,72 +146,373 @@ impl Match {
 }
 /// Matching errors are added to the `Match`.
-pub(super) fn match_(pattern: &MetaTemplate, src: &tt::Subtree) -> Match {
+pub(super) fn match_(pattern: &MetaTemplate, input: &tt::Subtree) -> Match {
-    let mut res = Match::default();
+    let mut res = match_loop(pattern, &input);
-    let mut src = TtIter::new(src);
+    res.bound_count = count(res.bindings.bindings());
+    return res;
+    fn count<'a>(bindings: impl Iterator<Item = &'a Binding>) -> usize {
+        bindings
+            .map(|it| match it {
+                Binding::Fragment(_) => 1,
+                Binding::Empty => 1,
+                Binding::Nested(it) => count(it.iter()),
+            })
+            .sum()
+    }
+}
-    match_tokens(&mut res, pattern, &mut src);
+#[derive(Debug, Clone)]
+struct MatchState<'t> {
+    /// The position of the "dot" in this matcher
+    dot: OpDelimitedIter<'t>,
-    if src.len() > 0 {
+    /// Token subtree stack
-        res.unmatched_tts += src.len();
+    /// When matching against matchers with nested delimited submatchers (e.g., `pat ( pat ( .. )
-        res.add_err(err!("leftover tokens"));
+    /// pat ) pat`), we need to keep track of the matchers we are descending into. This stack does
-    }
+    /// that where the bottom of the stack is the outermost matcher.
+    stack: SmallVec<[OpDelimitedIter<'t>; 4]>,
+    /// The "parent" matcher position if we are in a repetition. That is, the matcher position just
+    /// before we enter the repetition.
+    up: Option<Box<MatchState<'t>>>,
+    /// The separator if we are in a repetition.
+    sep: Option<Separator>,
+    /// The KleeneOp of this sequence if we are in a repetition.
+    sep_kind: Option<RepeatKind>,
-    res
+    /// Number of tokens of seperator parsed
+    sep_parsed: Option<usize>,
+    /// Matched meta variables bindings
+    bindings: SmallVec<[Bindings; 4]>,
+    /// Cached result of meta variable parsing
+    meta_result: Option<(TtIter<'t>, ExpandResult<Option<Fragment>>)>,
+    /// Is error occuried in this state, will `poised` to "parent"
+    is_error: bool,
 }
-fn match_tokens(res: &mut Match, pattern: &MetaTemplate, src: &mut TtIter) {
+/// Process the matcher positions of `cur_items` until it is empty. In the process, this will
-    for op in pattern.iter() {
+/// produce more items in `next_items`, `eof_items`, and `bb_items`.
-        match op {
+///
-            Op::Leaf(lhs) => {
+/// For more info about the how this happens, see the module-level doc comments and the inline
-                if let Err(err) = match_leaf(lhs, src) {
+/// comments of this function.
-                    res.add_err(err);
+///
-                    continue;
+/// # Parameters
+///
+/// - `src`: the current token of the parser.
+/// - `stack`: the "parent" frames of the token tree
+/// - `res`: the match result to store errors
+/// - `cur_items`: the set of current items to be processed. This should be empty by the end of a
+///   successful execution of this function.
+/// - `next_items`: the set of newly generated items. These are used to replenish `cur_items` in
+///   the function `parse`.
+/// - `eof_items`: the set of items that would be valid if this was the EOF.
+/// - `bb_items`: the set of items that are waiting for the black-box parser.
+/// - `error_items`: the set of items in errors, used for error-resilient parsing
+fn match_loop_inner<'t>(
+    src: TtIter<'t>,
+    stack: &[TtIter<'t>],
+    res: &mut Match,
+    cur_items: &mut SmallVec<[MatchState<'t>; 1]>,
+    bb_items: &mut SmallVec<[MatchState<'t>; 1]>,
+    next_items: &mut Vec<MatchState<'t>>,
+    eof_items: &mut SmallVec<[MatchState<'t>; 1]>,
+    error_items: &mut SmallVec<[MatchState<'t>; 1]>,
+) {
+    macro_rules! try_push {
+        ($items: expr, $it:expr) => {
+            if $it.is_error {
+                error_items.push($it);
+            } else {
+                $items.push($it);
+            }
+        };
+    }
+    while let Some(mut item) = cur_items.pop() {
+        while item.dot.is_eof() {
+            match item.stack.pop() {
+                Some(frame) => {
+                    item.dot = frame;
+                    item.dot.next();
                }
+                None => break,
            }
-            Op::Subtree { tokens, delimiter: delim } => {
+        }
-                let rhs = match src.expect_subtree() {
+        let op = match item.dot.peek() {
-                    Ok(s) => s,
+            None => {
-                    Err(()) => {
+                // We are at or past the end of the matcher of `item`.
-                        res.add_err(err!("expected subtree"));
+                if item.up.is_some() {
-                        continue;
+                    if item.sep_parsed.is_none() {
+                        // Get the `up` matcher
+                        let mut new_pos = *item.up.clone().unwrap();
+                        // Add matches from this repetition to the `matches` of `up`
+                        if let Some(bindings) = new_pos.bindings.last_mut() {
+                            for (i, b) in item.bindings.iter_mut().enumerate() {
+                                bindings.push_nested(i, b.clone()).unwrap();
+                            }
+                        }
+                        // Move the "dot" past the repetition in `up`
+                        new_pos.dot.next();
+                        new_pos.is_error = new_pos.is_error || item.is_error;
+                        cur_items.push(new_pos);
+                    }
+                    // Check if we need a separator.
+                    // We check the separator one by one
+                    let sep_idx = *item.sep_parsed.as_ref().unwrap_or(&0);
+                    let sep_len = item.sep.as_ref().map_or(0, Separator::tt_count);
+                    if item.sep.is_some() && sep_idx != sep_len {
+                        let sep = item.sep.as_ref().unwrap();
+                        if src.clone().expect_separator(&sep, sep_idx) {
+                            item.dot.next();
+                            item.sep_parsed = Some(sep_idx + 1);
+                            try_push!(next_items, item);
+                        }
+                    }
+                    // We don't need a separator. Move the "dot" back to the beginning of the matcher
+                    // and try to match again UNLESS we are only allowed to have _one_ repetition.
+                    else if item.sep_kind != Some(RepeatKind::ZeroOrOne) {
+                        item.dot = item.dot.reset();
+                        item.sep_parsed = None;
+                        item.bindings.push(Bindings::default());
+                        cur_items.push(item);
+                    }
+                } else {
+                    // If we are not in a repetition, then being at the end of a matcher means that we have
+                    // reached the potential end of the input.
+                    try_push!(eof_items, item);
+                }
+                continue;
+            }
+            Some(it) => it,
+        };
+        // We are in the middle of a matcher.
+        match op {
+            OpDelimited::Op(Op::Repeat { tokens, kind, separator }) => {
+                if matches!(kind, RepeatKind::ZeroOrMore | RepeatKind::ZeroOrOne) {
+                    let mut new_item = item.clone();
+                    new_item.dot.next();
+                    let mut vars = Vec::new();
+                    let bindings = new_item.bindings.last_mut().unwrap();
+                    collect_vars(&mut vars, tokens);
+                    for var in vars {
+                        bindings.push_empty(&var);
                    }
-                };
+                    cur_items.push(new_item);
-                if delim.map(|it| it.kind) != rhs.delimiter_kind() {
-                    res.add_err(err!("mismatched delimiter"));
-                    continue;
                }
-                let mut src = TtIter::new(rhs);
+                cur_items.push(MatchState {
-                match_tokens(res, tokens, &mut src);
+                    dot: tokens.iter_delimited(None),
-                if src.len() > 0 {
+                    stack: Default::default(),
-                    res.add_err(err!("leftover tokens"));
+                    up: Some(Box::new(item)),
+                    sep: separator.clone(),
+                    sep_kind: Some(*kind),
+                    sep_parsed: None,
+                    bindings: smallvec![Bindings::default()],
+                    meta_result: None,
+                    is_error: false,
+                })
+            }
+            OpDelimited::Op(Op::Subtree { tokens, delimiter }) => {
+                if let Ok(subtree) = src.clone().expect_subtree() {
+                    if subtree.delimiter_kind() == delimiter.map(|it| it.kind) {
+                        item.stack.push(item.dot);
+                        item.dot = tokens.iter_delimited(delimiter.as_ref());
+                        cur_items.push(item);
+                    }
                }
            }
-            Op::Var { name, kind, .. } => {
+            OpDelimited::Op(Op::Var { kind, name, .. }) => {
-                let kind = match kind {
+                if let Some(kind) = kind {
-                    Some(k) => k,
+                    let mut fork = src.clone();
-                    None => {
+                    let match_res = match_meta_var(kind.as_str(), &mut fork);
-                        res.add_err(ExpandError::UnexpectedToken);
+                    match match_res.err {
-                        continue;
+                        None => {
+                            // Some meta variables are optional (e.g. vis)
+                            if match_res.value.is_some() {
+                                item.meta_result = Some((fork, match_res));
+                                try_push!(bb_items, item);
+                            } else {
+                                item.bindings.last_mut().unwrap().push_optional(name);
+                                item.dot.next();
+                                cur_items.push(item);
+                            }
+                        }
+                        Some(err) => {
+                            res.add_err(err);
+                            match match_res.value {
+                                Some(fragment) => {
+                                    item.bindings
+                                        .last_mut()
+                                        .unwrap()
+                                        .inner
+                                        .push((name.clone(), Binding::Fragment(fragment)));
+                                }
+                                _ => {}
+                            }
+                            item.is_error = true;
+                            error_items.push(item);
+                        }
                    }
-                };
+                }
-                let ExpandResult { value: matched, err: match_err } =
+            }
-                    match_meta_var(kind.as_str(), src);
+            OpDelimited::Op(Op::Leaf(leaf)) => {
-                match matched {
+                if let Err(err) = match_leaf(&leaf, &mut src.clone()) {
+                    res.add_err(err);
+                    item.is_error = true;
+                } else {
+                    item.dot.next();
+                }
+                try_push!(next_items, item);
+            }
+            OpDelimited::Open => {
+                if matches!(src.clone().next(), Some(tt::TokenTree::Subtree(..))) {
+                    item.dot.next();
+                    try_push!(next_items, item);
+                }
+            }
+            OpDelimited::Close => {
+                let is_delim_closed = src.peek_n(0).is_none() && !stack.is_empty();
+                if is_delim_closed {
+                    item.dot.next();
+                    try_push!(next_items, item);
+                }
+            }
+        }
+    }
+}
+fn match_loop(pattern: &MetaTemplate, src: &tt::Subtree) -> Match {
+    let mut src = TtIter::new(src);
+    let mut stack: SmallVec<[TtIter; 1]> = SmallVec::new();
+    let mut res = Match::default();
+    let mut error_reover_item = None;
+    let mut cur_items = smallvec![MatchState {
+        dot: pattern.iter_delimited(None),
+        stack: Default::default(),
+        up: None,
+        sep: None,
+        sep_kind: None,
+        sep_parsed: None,
+        bindings: smallvec![Bindings::default()],
+        is_error: false,
+        meta_result: None,
+    }];
+    let mut next_items = vec![];
+    loop {
+        let mut bb_items = SmallVec::new();
+        let mut eof_items = SmallVec::new();
+        let mut error_items = SmallVec::new();
+        stdx::always!(next_items.is_empty());
+        match_loop_inner(
+            src.clone(),
+            &stack,
+            &mut res,
+            &mut cur_items,
+            &mut bb_items,
+            &mut next_items,
+            &mut eof_items,
+            &mut error_items,
+        );
+        stdx::always!(cur_items.is_empty());
+        if error_items.len() > 0 {
+            error_reover_item = error_items.pop();
+        } else if eof_items.len() > 0 {
+            error_reover_item = Some(eof_items[0].clone());
+        }
+        // We need to do some post processing after the `match_loop_inner`.
+        // If we reached the EOF, check that there is EXACTLY ONE possible matcher. Otherwise,
+        // either the parse is ambiguous (which should never happen) or there is a syntax error.
+        if src.peek_n(0).is_none() && stack.is_empty() {
+            if eof_items.len() == 1 {
+                // remove all errors, because it is the correct answer !
+                res = Match::default();
+                res.bindings = eof_items[0].bindings[0].clone();
+            } else {
+                // Error recovery
+                if error_reover_item.is_some() {
+                    res.bindings = error_reover_item.unwrap().bindings[0].clone();
+                }
+                res.add_err(ExpandError::UnexpectedToken);
+            }
+            return res;
+        }
+        // If there are no possible next positions AND we aren't waiting for the black-box parser,
+        // then there is a syntax error.
+        //
+        // Another possibility is that we need to call out to parse some rust nonterminal
+        // (black-box) parser. However, if there is not EXACTLY ONE of these, something is wrong.
+        if (bb_items.is_empty() && next_items.is_empty())
+            || (!bb_items.is_empty() && !next_items.is_empty())
+            || bb_items.len() > 1
+        {
+            res.unmatched_tts += src.len();
+            while let Some(it) = stack.pop() {
+                src = it;
+                res.unmatched_tts += src.len();
+            }
+            res.add_err(err!("leftover tokens"));
+            if let Some(mut error_reover_item) = error_reover_item {
+                res.bindings = error_reover_item.bindings.remove(0);
+            }
+            return res;
+        }
+        // Dump all possible `next_items` into `cur_items` for the next iteration.
+        else if !next_items.is_empty() {
+            // Now process the next token
+            cur_items.extend(next_items.drain(..));
+            match src.next() {
+                Some(tt::TokenTree::Subtree(subtree)) => {
+                    stack.push(src.clone());
+                    src = TtIter::new(subtree);
+                }
+                None if !stack.is_empty() => src = stack.pop().unwrap(),
+                _ => (),
+            }
+        }
+        // Finally, we have the case where we need to call the black-box parser to get some
+        // nonterminal.
+        else {
+            stdx::always!(bb_items.len() == 1);
+            let mut item = bb_items.pop().unwrap();
+            if let Some(OpDelimited::Op(Op::Var { name, .. })) = item.dot.peek() {
+                let (iter, match_res) = item.meta_result.take().unwrap();
+                let bindings = item.bindings.last_mut().unwrap();
+                match match_res.value {
                    Some(fragment) => {
-                        res.bindings.inner.insert(name.clone(), Binding::Fragment(fragment));
+                        bindings.inner.push((name.clone(), Binding::Fragment(fragment)));
                    }
-                    None if match_err.is_none() => res.bindings.push_optional(name),
+                    None if match_res.err.is_none() => bindings.push_optional(name),
                    _ => {}
                }
-                if let Some(err) = match_err {
+                if let Some(err) = match_res.err {
                    res.add_err(err);
                }
+                src = iter.clone();
+                item.dot.next();
+            } else {
+                unreachable!()
            }
-            Op::Repeat { tokens: subtree, kind, separator } => {
+            cur_items.push(item);
-                match_repeat(res, subtree, *kind, separator, src);
-            }
        }
+        stdx::always!(!cur_items.is_empty());
    }
 }
@@ -173,73 +544,6 @@ fn match_leaf(lhs: &tt::Leaf, src: &mut TtIter) -> Result<(), ExpandError> {
    Ok(())
 }
-fn match_repeat(
-    res: &mut Match,
-    pattern: &MetaTemplate,
-    kind: RepeatKind,
-    separator: &Option<Separator>,
-    src: &mut TtIter,
-) {
-    // Dirty hack to make macro-expansion terminate.
-    // This should be replaced by a proper macro-by-example implementation
-    let mut limit = 65536;
-    let mut counter = 0;
-    for i in 0.. {
-        let mut fork = src.clone();
-        if let Some(separator) = &separator {
-            if i != 0 && !fork.eat_separator(separator) {
-                break;
-            }
-        }
-        let mut nested = Match::default();
-        match_tokens(&mut nested, pattern, &mut fork);
-        if nested.err.is_none() {
-            limit -= 1;
-            if limit == 0 {
-                log::warn!(
-                    "match_lhs exceeded repeat pattern limit => {:#?}\n{:#?}\n{:#?}\n{:#?}",
-                    pattern,
-                    src,
-                    kind,
-                    separator
-                );
-                break;
-            }
-            *src = fork;
-            if let Err(err) = res.bindings.push_nested(counter, nested.bindings) {
-                res.add_err(err);
-            }
-            counter += 1;
-            if counter == 1 {
-                if let RepeatKind::ZeroOrOne = kind {
-                    break;
-                }
-            }
-        } else {
-            break;
-        }
-    }
-    match (kind, counter) {
-        (RepeatKind::OneOrMore, 0) => {
-            res.add_err(ExpandError::UnexpectedToken);
-        }
-        (_, 0) => {
-            // Collect all empty variables in subtrees
-            let mut vars = Vec::new();
-            collect_vars(&mut vars, pattern);
-            for var in vars {
-                res.bindings.push_empty(&var)
-            }
-        }
-        _ => (),
-    }
-}
 fn match_meta_var(kind: &str, input: &mut TtIter) -> ExpandResult<Option<Fragment>> {
    let fragment = match kind {
        "path" => Path,
@@ -303,14 +607,14 @@ fn collect_vars(buf: &mut Vec<SmolStr>, pattern: &MetaTemplate) {
 }
 impl<'a> TtIter<'a> {
-    fn eat_separator(&mut self, separator: &Separator) -> bool {
+    fn expect_separator(&mut self, separator: &Separator, idx: usize) -> bool {
        let mut fork = self.clone();
        let ok = match separator {
-            Separator::Ident(lhs) => match fork.expect_ident() {
+            Separator::Ident(lhs) if idx == 0 => match fork.expect_ident() {
                Ok(rhs) => rhs.text == lhs.text,
                _ => false,
            },
-            Separator::Literal(lhs) => match fork.expect_literal() {
+            Separator::Literal(lhs) if idx == 0 => match fork.expect_literal() {
                Ok(rhs) => match rhs {
                    tt::Leaf::Literal(rhs) => rhs.text == lhs.text,
                    tt::Leaf::Ident(rhs) => rhs.text == lhs.text,
@@ -318,10 +622,11 @@ impl<'a> TtIter<'a> {
                },
                _ => false,
            },
-            Separator::Puncts(lhss) => lhss.iter().all(|lhs| match fork.expect_punct() {
+            Separator::Puncts(lhss) if idx < lhss.len() => match fork.expect_punct() {
-                Ok(rhs) => rhs.char == lhs.char,
+                Ok(rhs) => rhs.char == lhss[idx].char,
                _ => false,
-            }),
+            },
+            _ => false,
        };
        if ok {
            *self = fork;
diff --git a/crates/mbe/src/expander/transcriber.rs b/crates/mbe/src/expander/transcriber.rs
index 78368a33e..ad9953a7d 100644
--- a/crates/mbe/src/expander/transcriber.rs
+++ b/crates/mbe/src/expander/transcriber.rs
@@ -13,13 +13,17 @@ use crate::{
 impl Bindings {
    fn contains(&self, name: &str) -> bool {
-        self.inner.contains_key(name)
+        self.inner.iter().any(|(n, _)| n == name)
    }
    fn get(&self, name: &str, nesting: &mut [NestingState]) -> Result<&Fragment, ExpandError> {
-        let mut b = self.inner.get(name).ok_or_else(|| {
+        let mut b: &Binding = self
-            ExpandError::BindingError(format!("could not find binding `{}`", name))
+            .inner
-        })?;
+            .iter()
+            .find_map(|(n, b)| if n == name { Some(b) } else { None })
+            .ok_or_else(|| {
+                ExpandError::BindingError(format!("could not find binding `{}`", name))
+            })?;
        for nesting_state in nesting.iter_mut() {
            nesting_state.hit = true;
            b = match b {
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index 4c298f85f..f3d2da55a 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -21,7 +21,7 @@ use test_utils::mark;
 pub use tt::{Delimiter, DelimiterKind, Punct};
 use crate::{
-    parser::{parse_pattern, parse_template, Op},
+    parser::{parse_pattern, parse_template, MetaTemplate, Op},
    tt_iter::TtIter,
 };
@@ -94,15 +94,6 @@ struct Rule {
    rhs: MetaTemplate,
 }
-#[derive(Clone, Debug, PartialEq, Eq)]
-struct MetaTemplate(Vec<Op>);
-impl<'a> MetaTemplate {
-    fn iter(&self) -> impl Iterator<Item = &Op> {
-        self.0.iter()
-    }
-}
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 struct Shift(u32);
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index f891ec29c..8671322e1 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -5,7 +5,75 @@ use smallvec::SmallVec;
 use syntax::SmolStr;
 use tt::Delimiter;
-use crate::{tt_iter::TtIter, MetaTemplate, ParseError};
+use crate::{tt_iter::TtIter, ParseError};
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct MetaTemplate(pub(crate) Vec<Op>);
+#[derive(Debug, Clone, Copy)]
+pub(crate) enum OpDelimited<'a> {
+    Op(&'a Op),
+    Open,
+    Close,
+}
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct OpDelimitedIter<'a> {
+    inner: &'a Vec<Op>,
+    delimited: Option<&'a Delimiter>,
+    idx: usize,
+}
+impl<'a> OpDelimitedIter<'a> {
+    pub(crate) fn is_eof(&self) -> bool {
+        let len = self.inner.len() + if self.delimited.is_some() { 2 } else { 0 };
+        self.idx >= len
+    }
+    pub(crate) fn peek(&self) -> Option<OpDelimited<'a>> {
+        match self.delimited {
+            None => self.inner.get(self.idx).map(OpDelimited::Op),
+            Some(_) => match self.idx {
+                0 => Some(OpDelimited::Open),
+                i if i == self.inner.len() + 1 => Some(OpDelimited::Close),
+                i => self.inner.get(i - 1).map(OpDelimited::Op),
+            },
+        }
+    }
+    pub(crate) fn reset(&self) -> Self {
+        Self { inner: &self.inner, idx: 0, delimited: self.delimited }
+    }
+}
+impl<'a> Iterator for OpDelimitedIter<'a> {
+    type Item = OpDelimited<'a>;
+    fn next(&mut self) -> Option<Self::Item> {
+        let res = self.peek();
+        self.idx += 1;
+        res
+    }
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.inner.len() + if self.delimited.is_some() { 2 } else { 0 };
+        let remain = len.checked_sub(self.idx).unwrap_or(0);
+        (remain, Some(remain))
+    }
+}
+impl<'a> MetaTemplate {
+    pub(crate) fn iter(&self) -> impl Iterator<Item = &Op> {
+        self.0.iter()
+    }
+    pub(crate) fn iter_delimited(
+        &'a self,
+        delimited: Option<&'a Delimiter>,
+    ) -> OpDelimitedIter<'a> {
+        OpDelimitedIter { inner: &self.0, idx: 0, delimited }
+    }
+}
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) enum Op {
@@ -47,6 +115,16 @@ impl PartialEq for Separator {
    }
 }
+impl Separator {
+    pub(crate) fn tt_count(&self) -> usize {
+        match self {
+            Separator::Literal(_) => 1,
+            Separator::Ident(_) => 1,
+            Separator::Puncts(it) => it.len(),
+        }
+    }
+}
 pub(crate) fn parse_template(template: &tt::Subtree) -> Result<Vec<Op>, ParseError> {
    parse_inner(&template, Mode::Template).into_iter().collect()
 }
diff --git a/crates/mbe/src/tests.rs b/crates/mbe/src/tests.rs
index f1eadcd1e..5c641ebf2 100644
--- a/crates/mbe/src/tests.rs
+++ b/crates/mbe/src/tests.rs
@@ -457,6 +457,17 @@ fn test_match_group_with_multichar_sep() {
 }
 #[test]
+fn test_match_group_with_multichar_sep2() {
+    parse_macro(
+        r#"
+        macro_rules! foo {
+            (fn $name:ident {$($i:literal)&&*} ) => ( fn $name() -> bool { $($i)&&*} );
+        }"#,
+    )
+    .assert_expand_items("foo! (fn baz {true && true} );", "fn baz () -> bool {true &&true}");
+}
+#[test]
 fn test_match_group_zero_match() {
    parse_macro(
        r#"
@@ -1267,6 +1278,18 @@ macro_rules! m {
    .is_some());
 }
+#[test]
+fn test_match_is_not_greedy() {
+    parse_macro(
+        r#"
+macro_rules! foo {
+    ($($i:ident $(,)*),*) => {};
+}
+"#,
+    )
+    .assert_expand_items(r#"foo!(a,b);"#, r#""#);
+}
 // The following tests are based on real world situations
 #[test]
 fn test_vec() {
diff --git a/crates/proc_macro_srv/Cargo.toml b/crates/proc_macro_srv/Cargo.toml
index 6c8c28980..4c1b3036a 100644
--- a/crates/proc_macro_srv/Cargo.toml
+++ b/crates/proc_macro_srv/Cargo.toml
@@ -20,7 +20,7 @@ proc_macro_api = { path = "../proc_macro_api", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
 [dev-dependencies]
-cargo_metadata = "0.12.2"
+cargo_metadata = "0.13"
 # used as proc macro test targets
 serde_derive = "1.0.106"
diff --git a/crates/proc_macro_srv/src/rustc_server.rs b/crates/proc_macro_srv/src/rustc_server.rs
index a8504f762..952b4a97f 100644
--- a/crates/proc_macro_srv/src/rustc_server.rs
+++ b/crates/proc_macro_srv/src/rustc_server.rs
@@ -14,7 +14,6 @@ use std::collections::HashMap;
 use std::hash::Hash;
 use std::iter::FromIterator;
 use std::ops::Bound;
-use std::str::FromStr;
 use std::{ascii, vec::IntoIter};
 type Group = tt::Subtree;
@@ -278,6 +277,42 @@ impl server::FreeFunctions for Rustc {
    }
 }
+fn subtree_replace_token_ids_with_unspecified(subtree: tt::Subtree) -> tt::Subtree {
+    tt::Subtree {
+        delimiter: subtree.delimiter.map(|d| tt::Delimiter { id: tt::TokenId::unspecified(), ..d }),
+        token_trees: subtree
+            .token_trees
+            .into_iter()
+            .map(|t| token_tree_replace_token_ids_with_unspecified(t))
+            .collect(),
+    }
+}
+fn token_tree_replace_token_ids_with_unspecified(tt: tt::TokenTree) -> tt::TokenTree {
+    match tt {
+        tt::TokenTree::Leaf(leaf) => {
+            tt::TokenTree::Leaf(leaf_replace_token_ids_with_unspecified(leaf))
+        }
+        tt::TokenTree::Subtree(subtree) => {
+            tt::TokenTree::Subtree(subtree_replace_token_ids_with_unspecified(subtree))
+        }
+    }
+}
+fn leaf_replace_token_ids_with_unspecified(leaf: tt::Leaf) -> tt::Leaf {
+    match leaf {
+        tt::Leaf::Literal(lit) => {
+            tt::Leaf::Literal(tt::Literal { id: tt::TokenId::unspecified(), ..lit })
+        }
+        tt::Leaf::Punct(punct) => {
+            tt::Leaf::Punct(tt::Punct { id: tt::TokenId::unspecified(), ..punct })
+        }
+        tt::Leaf::Ident(ident) => {
+            tt::Leaf::Ident(tt::Ident { id: tt::TokenId::unspecified(), ..ident })
+        }
+    }
+}
 impl server::TokenStream for Rustc {
    fn new(&mut self) -> Self::TokenStream {
        Self::TokenStream::new()
@@ -287,7 +322,8 @@ impl server::TokenStream for Rustc {
        stream.is_empty()
    }
    fn from_str(&mut self, src: &str) -> Self::TokenStream {
-        Self::TokenStream::from_str(src).expect("cannot parse string")
+        let (subtree, _) = mbe::parse_to_token_tree(src).expect("cannot parse string");
+        TokenStream::with_subtree(subtree_replace_token_ids_with_unspecified(subtree))
    }
    fn to_string(&mut self, stream: &Self::TokenStream) -> String {
        stream.to_string()
diff --git a/crates/proc_macro_srv/src/tests/utils.rs b/crates/proc_macro_srv/src/tests/utils.rs
index 196abb8fc..22813052d 100644
--- a/crates/proc_macro_srv/src/tests/utils.rs
+++ b/crates/proc_macro_srv/src/tests/utils.rs
@@ -8,6 +8,7 @@ use test_utils::assert_eq_text;
 mod fixtures {
    use cargo_metadata::Message;
+    use std::path::PathBuf;
    use std::process::Command;
    // Use current project metadata to get the proc-macro dylib path
@@ -24,7 +25,7 @@ mod fixtures {
                    if artifact.target.kind.contains(&"proc-macro".to_string()) {
                        let repr = format!("{} {}", crate_name, version);
                        if artifact.package_id.repr.starts_with(&repr) {
-                            return artifact.filenames[0].clone();
+                            return PathBuf::from(&artifact.filenames[0]);
                        }
                    }
                }
diff --git a/crates/project_model/Cargo.toml b/crates/project_model/Cargo.toml
index 293cb5bfe..fe3258332 100644
--- a/crates/project_model/Cargo.toml
+++ b/crates/project_model/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 log = "0.4.8"
 rustc-hash = "1.1.0"
-cargo_metadata = "0.12.2"
+cargo_metadata = "0.13"
 serde = { version = "1.0.106", features = ["derive"] }
 serde_json = "1.0.48"
 anyhow = "1.0.26"
@@ -22,7 +22,7 @@ la-arena = { version = "0.2.0", path = "../../lib/arena" }
 cfg = { path = "../cfg", version = "0.0.0" }
 base_db = { path = "../base_db", version = "0.0.0" }
 toolchain = { path = "../toolchain", version = "0.0.0" }
-proc_macro_api =  { path = "../proc_macro_api", version = "0.0.0" }
+proc_macro_api = { path = "../proc_macro_api", version = "0.0.0" }
-paths =  { path = "../paths", version = "0.0.0" }
+paths = { path = "../paths", version = "0.0.0" }
-stdx =  { path = "../stdx", version = "0.0.0" }
+stdx = { path = "../stdx", version = "0.0.0" }
-profile =  { path = "../profile", version = "0.0.0" }
+profile = { path = "../profile", version = "0.0.0" }
diff --git a/crates/project_model/src/build_data.rs b/crates/project_model/src/build_data.rs
index 295b5f8ef..728a258ea 100644
--- a/crates/project_model/src/build_data.rs
+++ b/crates/project_model/src/build_data.rs
@@ -1,14 +1,14 @@
 //! Handles build script specific information
 use std::{
-    ffi::OsStr,
    io::BufReader,
-    path::{Path, PathBuf},
+    path::PathBuf,
    process::{Command, Stdio},
    sync::Arc,
 };
 use anyhow::Result;
+use cargo_metadata::camino::Utf8Path;
 use cargo_metadata::{BuildScript, Message};
 use itertools::Itertools;
 use paths::{AbsPath, AbsPathBuf};
@@ -162,8 +162,8 @@ fn collect_from_workspace(
                    let res = res.entry(package_id.repr.clone()).or_default();
                    // cargo_metadata crate returns default (empty) path for
                    // older cargos, which is not absolute, so work around that.
-                    if out_dir != PathBuf::default() {
+                    if !out_dir.as_str().is_empty() {
-                        let out_dir = AbsPathBuf::assert(out_dir);
+                        let out_dir = AbsPathBuf::assert(PathBuf::from(out_dir.into_os_string()));
                        res.out_dir = Some(out_dir);
                        res.cfgs = cfgs;
                    }
@@ -178,7 +178,7 @@ fn collect_from_workspace(
                        // Skip rmeta file
                        if let Some(filename) = message.filenames.iter().find(|name| is_dylib(name))
                        {
-                            let filename = AbsPathBuf::assert(filename.clone());
+                            let filename = AbsPathBuf::assert(PathBuf::from(&filename));
                            let res = res.entry(package_id.repr.clone()).or_default();
                            res.proc_macro_dylib_path = Some(filename);
                        }
@@ -187,9 +187,9 @@ fn collect_from_workspace(
                Message::CompilerMessage(message) => {
                    progress(message.target.name.clone());
                }
-                Message::Unknown => (),
                Message::BuildFinished(_) => {}
                Message::TextLine(_) => {}
+                _ => {}
            }
        }
    }
@@ -209,8 +209,8 @@ fn collect_from_workspace(
 }
 // FIXME: File a better way to know if it is a dylib
-fn is_dylib(path: &Path) -> bool {
+fn is_dylib(path: &Utf8Path) -> bool {
-    match path.extension().and_then(OsStr::to_str).map(|it| it.to_string().to_lowercase()) {
+    match path.extension().map(|e| e.to_string().to_lowercase()) {
        None => false,
        Some(ext) => matches!(ext.as_str(), "dll" | "dylib" | "so"),
    }
@@ -227,9 +227,7 @@ fn inject_cargo_env(package: &cargo_metadata::Package, build_data: &mut BuildDat
    let mut manifest_dir = package.manifest_path.clone();
    manifest_dir.pop();
-    if let Some(cargo_manifest_dir) = manifest_dir.to_str() {
+    env.push(("CARGO_MANIFEST_DIR".into(), manifest_dir.into_string()));
-        env.push(("CARGO_MANIFEST_DIR".into(), cargo_manifest_dir.into()));
-    }
    // Not always right, but works for common cases.
    env.push(("CARGO".into(), "cargo".into()));
@@ -251,7 +249,6 @@ fn inject_cargo_env(package: &cargo_metadata::Package, build_data: &mut BuildDat
    env.push(("CARGO_PKG_REPOSITORY".into(), package.repository.clone().unwrap_or_default()));
    env.push(("CARGO_PKG_LICENSE".into(), package.license.clone().unwrap_or_default()));
-    let license_file =
+    let license_file = package.license_file.as_ref().map(|buf| buf.to_string()).unwrap_or_default();
-        package.license_file.as_ref().map(|buf| buf.display().to_string()).unwrap_or_default();
    env.push(("CARGO_PKG_LICENSE_FILE".into(), license_file));
 }
diff --git a/crates/project_model/src/cargo_workspace.rs b/crates/project_model/src/cargo_workspace.rs
index 1d8d34a0b..f7241b711 100644
--- a/crates/project_model/src/cargo_workspace.rs
+++ b/crates/project_model/src/cargo_workspace.rs
@@ -1,5 +1,6 @@
 //! FIXME: write short doc here
+use std::path::PathBuf;
 use std::{convert::TryInto, ops, process::Command, sync::Arc};
 use anyhow::{Context, Result};
@@ -249,11 +250,12 @@ impl CargoWorkspace {
            let edition = edition
                .parse::<Edition>()
                .with_context(|| format!("Failed to parse edition {}", edition))?;
            let pkg = packages.alloc(PackageData {
                id: id.repr.clone(),
                name: name.clone(),
                version: version.to_string(),
-                manifest: AbsPathBuf::assert(manifest_path.clone()),
+                manifest: AbsPathBuf::assert(PathBuf::from(&manifest_path)),
                targets: Vec::new(),
                is_member,
                edition,
@@ -268,7 +270,7 @@ impl CargoWorkspace {
                let tgt = targets.alloc(TargetData {
                    package: pkg,
                    name: meta_tgt.name.clone(),
-                    root: AbsPathBuf::assert(meta_tgt.src_path.clone()),
+                    root: AbsPathBuf::assert(PathBuf::from(&meta_tgt.src_path)),
                    kind: TargetKind::new(meta_tgt.kind.as_slice()),
                    is_proc_macro,
                });
@@ -305,7 +307,8 @@ impl CargoWorkspace {
            packages[source].active_features.extend(node.features);
        }
-        let workspace_root = AbsPathBuf::assert(meta.workspace_root);
+        let workspace_root =
+            AbsPathBuf::assert(PathBuf::from(meta.workspace_root.into_os_string()));
        let build_data_config = BuildDataConfig::new(
            cargo_toml.to_path_buf(),
            config.clone(),
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index b881cc229..8789f0852 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -24,7 +24,7 @@ jod-thread = "0.1.0"
 log = "0.4.8"
 lsp-types = { version = "0.88.0", features = ["proposed"] }
 parking_lot = "0.11.0"
-pico-args = "0.4.0"
+xflags = "0.1.2"
 oorandom = "11.1.2"
 rustc-hash = "1.1.0"
 serde = { version = "1.0.106", features = ["derive"] }
diff --git a/crates/rust-analyzer/src/bin/args.rs b/crates/rust-analyzer/src/bin/args.rs
deleted file mode 100644
index 164d94a30..000000000
--- a/crates/rust-analyzer/src/bin/args.rs
+++ /dev/null
@@ -1,274 +0,0 @@
-//! Command like parsing for rust-analyzer.
-//!
-//! If run started args, we run the LSP server loop. With a subcommand, we do a
-//! one-time batch processing.
-use std::{env, path::PathBuf};
-use anyhow::{bail, format_err, Result};
-use ide_ssr::{SsrPattern, SsrRule};
-use pico_args::Arguments;
-use rust_analyzer::cli::{AnalysisStatsCmd, BenchCmd, BenchWhat, Position, Verbosity};
-use vfs::AbsPathBuf;
-pub(crate) struct Args {
-    pub(crate) verbosity: Verbosity,
-    pub(crate) log_file: Option<PathBuf>,
-    pub(crate) no_buffering: bool,
-    pub(crate) command: Command,
-    #[allow(unused)]
-    pub(crate) wait_dbg: bool,
-}
-pub(crate) enum Command {
-    Parse { no_dump: bool },
-    Symbols,
-    Highlight { rainbow: bool },
-    AnalysisStats(AnalysisStatsCmd),
-    Bench(BenchCmd),
-    Diagnostics { path: PathBuf, load_output_dirs: bool, with_proc_macro: bool },
-    Ssr { rules: Vec<SsrRule> },
-    StructuredSearch { debug_snippet: Option<String>, patterns: Vec<SsrPattern> },
-    ProcMacro,
-    RunServer,
-    PrintConfigSchema,
-    Version,
-    Help,
-}
-const HELP: &str = "\
-rust-analyzer
-USAGE:
-    rust-analyzer [FLAGS] [COMMAND] [COMMAND_OPTIONS]
-FLAGS:
-    --version         Print version
-    -h, --help        Print this help
-    -v,  --verbose
-    -vv, --spammy
-    -q,  --quiet      Set verbosity
-    --print-config-schema
-                      Dump a LSP config JSON schema
-    --log-file <PATH> Log to the specified file instead of stderr
-    --no-log-buffering
-                      Flush log records to the file immediately
-    --wait-dbg        Wait until a debugger is attached to.
-                      The flag is valid for debug builds only
-ENVIRONMENTAL VARIABLES:
-    RA_LOG            Set log filter in env_logger format
-    RA_PROFILE        Enable hierarchical profiler
-    RA_WAIT_DBG       If set acts like a --wait-dbg flag
-COMMANDS:
-not specified         Launch LSP server
-parse < main.rs       Parse tree
-    --no-dump         Suppress printing
-symbols < main.rs     Parse input an print the list of symbols
-highlight < main.rs   Highlight input as html
-    --rainbow         Enable rainbow highlighting of identifiers
-analysis-stats <PATH> Batch typecheck project and print summary statistics
-    <PATH>            Directory with Cargo.toml
-    --randomize       Randomize order in which crates, modules, and items are processed
-    --parallel        Run type inference in parallel
-    --memory-usage    Collect memory usage statistics
-    -o, --only <PATH> Only analyze items matching this path
-    --with-deps       Also analyze all dependencies
-    --load-output-dirs
-                      Load OUT_DIR values by running `cargo check` before analysis
-    --with-proc-macro Use proc-macro-srv for proc-macro expanding
-analysis-bench <PATH> Benchmark specific analysis operation
-    <PATH>            Directory with Cargo.toml
-    --highlight <PATH>
-                      Compute syntax highlighting for this file
-    --complete <PATH:LINE:COLUMN>
-                      Compute completions at this location
-    --goto-def <PATH:LINE:COLUMN>
-                      Compute goto definition at this location
-    --memory-usage    Collect memory usage statistics
-    --load-output-dirs
-                      Load OUT_DIR values by running `cargo check` before analysis
-    --with-proc-macro Use proc-macro-srv for proc-macro expanding
-diagnostics <PATH>
-    <PATH>            Directory with Cargo.toml
-    --load-output-dirs
-                      Load OUT_DIR values by running `cargo check` before analysis
-    --with-proc-macro Use proc-macro-srv for proc-macro expanding
-ssr [RULE...]
-    <RULE>            A structured search replace rule (`$a.foo($b) ==> bar($a, $b)`)
-search [PATTERN..]
-    <PATTERN>         A structured search replace pattern (`$a.foo($b)`)
-    --debug <snippet> Prints debug information for any nodes with source exactly
-                      equal to <snippet>
-";
-impl Args {
-    pub(crate) fn parse() -> Result<Args> {
-        let mut matches = Arguments::from_env();
-        if matches.contains("--version") {
-            finish_args(matches)?;
-            return Ok(Args {
-                verbosity: Verbosity::Normal,
-                log_file: None,
-                command: Command::Version,
-                no_buffering: false,
-                wait_dbg: false,
-            });
-        }
-        let verbosity = match (
-            matches.contains(["-vv", "--spammy"]),
-            matches.contains(["-v", "--verbose"]),
-            matches.contains(["-q", "--quiet"]),
-        ) {
-            (true, _, true) => bail!("Invalid flags: -q conflicts with -vv"),
-            (true, _, false) => Verbosity::Spammy,
-            (false, false, false) => Verbosity::Normal,
-            (false, false, true) => Verbosity::Quiet,
-            (false, true, false) => Verbosity::Verbose,
-            (false, true, true) => bail!("Invalid flags: -q conflicts with -v"),
-        };
-        let log_file = matches.opt_value_from_str("--log-file")?;
-        let no_buffering = matches.contains("--no-log-buffering");
-        let wait_dbg = matches.contains("--wait-dbg");
-        if matches.contains(["-h", "--help"]) {
-            eprintln!("{}", HELP);
-            return Ok(Args {
-                verbosity,
-                log_file: None,
-                command: Command::Help,
-                no_buffering,
-                wait_dbg,
-            });
-        }
-        if matches.contains("--print-config-schema") {
-            return Ok(Args {
-                verbosity,
-                log_file,
-                command: Command::PrintConfigSchema,
-                no_buffering,
-                wait_dbg,
-            });
-        }
-        let subcommand = match matches.subcommand()? {
-            Some(it) => it,
-            None => {
-                finish_args(matches)?;
-                return Ok(Args {
-                    verbosity,
-                    log_file,
-                    command: Command::RunServer,
-                    no_buffering,
-                    wait_dbg,
-                });
-            }
-        };
-        let command = match subcommand.as_str() {
-            "parse" => Command::Parse { no_dump: matches.contains("--no-dump") },
-            "symbols" => Command::Symbols,
-            "highlight" => Command::Highlight { rainbow: matches.contains("--rainbow") },
-            "analysis-stats" => Command::AnalysisStats(AnalysisStatsCmd {
-                randomize: matches.contains("--randomize"),
-                parallel: matches.contains("--parallel"),
-                memory_usage: matches.contains("--memory-usage"),
-                only: matches.opt_value_from_str(["-o", "--only"])?,
-                with_deps: matches.contains("--with-deps"),
-                load_output_dirs: matches.contains("--load-output-dirs"),
-                with_proc_macro: matches.contains("--with-proc-macro"),
-                path: matches
-                    .opt_free_from_str()?
-                    .ok_or_else(|| format_err!("expected positional argument"))?,
-            }),
-            "analysis-bench" => Command::Bench(BenchCmd {
-                what: {
-                    let highlight_path: Option<String> =
-                        matches.opt_value_from_str("--highlight")?;
-                    let complete_path: Option<Position> =
-                        matches.opt_value_from_str("--complete")?;
-                    let goto_def_path: Option<Position> =
-                        matches.opt_value_from_str("--goto-def")?;
-                    match (highlight_path, complete_path, goto_def_path) {
-                            (Some(path), None, None) => {
-                                let path = env::current_dir().unwrap().join(path);
-                                BenchWhat::Highlight { path: AbsPathBuf::assert(path) }
-                            }
-                            (None, Some(position), None) => BenchWhat::Complete(position),
-                            (None, None, Some(position)) => BenchWhat::GotoDef(position),
-                            _ => panic!(
-                                "exactly one of  `--highlight`, `--complete` or `--goto-def` must be set"
-                            ),
-                        }
-                },
-                memory_usage: matches.contains("--memory-usage"),
-                load_output_dirs: matches.contains("--load-output-dirs"),
-                with_proc_macro: matches.contains("--with-proc-macro"),
-                path: matches
-                    .opt_free_from_str()?
-                    .ok_or_else(|| format_err!("expected positional argument"))?,
-            }),
-            "diagnostics" => Command::Diagnostics {
-                load_output_dirs: matches.contains("--load-output-dirs"),
-                with_proc_macro: matches.contains("--with-proc-macro"),
-                path: matches
-                    .opt_free_from_str()?
-                    .ok_or_else(|| format_err!("expected positional argument"))?,
-            },
-            "proc-macro" => Command::ProcMacro,
-            "ssr" => Command::Ssr {
-                rules: {
-                    let mut acc = Vec::new();
-                    while let Some(rule) = matches.opt_free_from_str()? {
-                        acc.push(rule);
-                    }
-                    acc
-                },
-            },
-            "search" => Command::StructuredSearch {
-                debug_snippet: matches.opt_value_from_str("--debug")?,
-                patterns: {
-                    let mut acc = Vec::new();
-                    while let Some(rule) = matches.opt_free_from_str()? {
-                        acc.push(rule);
-                    }
-                    acc
-                },
-            },
-            _ => {
-                eprintln!("{}", HELP);
-                return Ok(Args {
-                    verbosity,
-                    log_file: None,
-                    command: Command::Help,
-                    no_buffering,
-                    wait_dbg,
-                });
-            }
-        };
-        finish_args(matches)?;
-        Ok(Args { verbosity, log_file, command, no_buffering, wait_dbg })
-    }
-}
-fn finish_args(args: Arguments) -> Result<()> {
-    if !args.finish().is_empty() {
-        bail!("Unused arguments.");
-    }
-    Ok(())
-}
diff --git a/crates/rust-analyzer/src/bin/flags.rs b/crates/rust-analyzer/src/bin/flags.rs
new file mode 100644
index 000000000..244912d26
--- /dev/null
+++ b/crates/rust-analyzer/src/bin/flags.rs
@@ -0,0 +1,251 @@
+//! Grammar for the command-line arguments.
+#![allow(unreachable_pub)]
+use std::{env, path::PathBuf};
+use ide_ssr::{SsrPattern, SsrRule};
+use rust_analyzer::cli::{BenchWhat, Position, Verbosity};
+use vfs::AbsPathBuf;
+xflags::args_parser! {
+    /// LSP server for the Rust programming language.
+    cmd rust-analyzer {
+        /// Verbosity level, can be repeated multiple times.
+        repeated -v, --verbose
+        /// Verbosity level.
+        optional -q, --quiet
+        /// Log to the specified file instead of stderr.
+        optional --log-file path: PathBuf
+        /// Flush log records to the file immediately.
+        optional --no-log-buffering
+        /// Wait until a debugger is attached to (requires debug build).
+        optional --wait-dbg
+        default cmd lsp-server {
+            /// Print version.
+            optional --version
+            /// Print help.
+            optional -h, --help
+            /// Dump a LSP config JSON schema.
+            optional --print-config-schema
+        }
+        /// Parse stdin.
+        cmd parse {
+            /// Suppress printing.
+            optional --no-dump
+        }
+        /// Parse stdin and print the list of symbols.
+        cmd symbols {}
+        /// Highlight stdin as html.
+        cmd highlight {
+            /// Enable rainbow highlighting of identifiers.
+            optional --rainbow
+        }
+        /// Batch typecheck project and print summary statistics
+        cmd analysis-stats
+            /// Directory with Cargo.toml.
+            required path: PathBuf
+        {
+            /// Randomize order in which crates, modules, and items are processed.
+            optional --randomize
+            /// Run type inference in parallel.
+            optional --parallel
+            /// Collect memory usage statistics.
+            optional --memory-usage
+            /// Only analyze items matching this path.
+            optional -o, --only path: String
+            /// Also analyze all dependencies.
+            optional --with-deps
+            /// Load OUT_DIR values by running `cargo check` before analysis.
+            optional --load-output-dirs
+            /// Use proc-macro-srv for proc-macro expanding.
+            optional --with-proc-macro
+        }
+        /// Benchmark specific analysis operation
+        cmd analysis-bench
+            /// Directory with Cargo.toml.
+            required path: PathBuf
+        {
+            /// Collect memory usage statistics.
+            optional --memory-usage
+            /// Compute syntax highlighting for this file
+            optional --highlight path: PathBuf
+            /// Compute completions at file:line:column location.
+            optional --complete location: Position
+            /// Compute goto definition at file:line:column location.
+            optional --goto-def location: Position
+            /// Load OUT_DIR values by running `cargo check` before analysis.
+            optional --load-output-dirs
+            /// Use proc-macro-srv for proc-macro expanding.
+            optional --with-proc-macro
+        }
+        cmd diagnostics
+            /// Directory with Cargo.toml.
+            required path: PathBuf
+        {
+            /// Load OUT_DIR values by running `cargo check` before analysis.
+            optional --load-output-dirs
+            /// Use proc-macro-srv for proc-macro expanding.
+            optional --with-proc-macro
+        }
+        cmd ssr
+            /// A structured search replace rule (`$a.foo($b) ==> bar($a, $b)`)
+            repeated rule: SsrRule
+        {}
+        cmd search
+            /// A structured search replace pattern (`$a.foo($b)`)
+            repeated pattern: SsrPattern
+        {
+            /// Prints debug information for any nodes with source exactly equal to snippet.
+            optional --debug snippet: String
+        }
+        cmd proc-macro {}
+    }
+}
+// generated start
+// The following code is generated by `xflags` macro.
+// Run `env XFLAGS_DUMP= cargo build` to regenerate.
+#[derive(Debug)]
+pub struct RustAnalyzer {
+    pub verbose: u32,
+    pub quiet: bool,
+    pub log_file: Option<PathBuf>,
+    pub no_log_buffering: bool,
+    pub wait_dbg: bool,
+    pub subcommand: RustAnalyzerCmd,
+}
+#[derive(Debug)]
+pub enum RustAnalyzerCmd {
+    LspServer(LspServer),
+    Parse(Parse),
+    Symbols(Symbols),
+    Highlight(Highlight),
+    AnalysisStats(AnalysisStats),
+    AnalysisBench(AnalysisBench),
+    Diagnostics(Diagnostics),
+    Ssr(Ssr),
+    Search(Search),
+    ProcMacro(ProcMacro),
+}
+#[derive(Debug)]
+pub struct LspServer {
+    pub version: bool,
+    pub help: bool,
+    pub print_config_schema: bool,
+}
+#[derive(Debug)]
+pub struct Parse {
+    pub no_dump: bool,
+}
+#[derive(Debug)]
+pub struct Symbols {}
+#[derive(Debug)]
+pub struct Highlight {
+    pub rainbow: bool,
+}
+#[derive(Debug)]
+pub struct AnalysisStats {
+    pub path: PathBuf,
+    pub randomize: bool,
+    pub parallel: bool,
+    pub memory_usage: bool,
+    pub only: Option<String>,
+    pub with_deps: bool,
+    pub load_output_dirs: bool,
+    pub with_proc_macro: bool,
+}
+#[derive(Debug)]
+pub struct AnalysisBench {
+    pub path: PathBuf,
+    pub memory_usage: bool,
+    pub highlight: Option<PathBuf>,
+    pub complete: Option<Position>,
+    pub goto_def: Option<Position>,
+    pub load_output_dirs: bool,
+    pub with_proc_macro: bool,
+}
+#[derive(Debug)]
+pub struct Diagnostics {
+    pub path: PathBuf,
+    pub load_output_dirs: bool,
+    pub with_proc_macro: bool,
+}
+#[derive(Debug)]
+pub struct Ssr {
+    pub rule: Vec<SsrRule>,
+}
+#[derive(Debug)]
+pub struct Search {
+    pub pattern: Vec<SsrPattern>,
+    pub debug: Option<String>,
+}
+#[derive(Debug)]
+pub struct ProcMacro {}
+impl RustAnalyzer {
+    pub const HELP: &'static str = Self::_HELP;
+    pub fn from_env() -> xflags::Result<Self> {
+        let mut p = xflags::rt::Parser::new_from_env();
+        Self::_parse(&mut p)
+    }
+}
+// generated end
+impl RustAnalyzer {
+    pub(crate) fn verbosity(&self) -> Verbosity {
+        if self.quiet {
+            return Verbosity::Quiet;
+        }
+        match self.verbose {
+            0 => Verbosity::Normal,
+            1 => Verbosity::Verbose,
+            _ => Verbosity::Spammy,
+        }
+    }
+}
+impl AnalysisBench {
+    pub(crate) fn what(&self) -> BenchWhat {
+        match (&self.highlight, &self.complete, &self.goto_def) {
+            (Some(path), None, None) => {
+                let path = env::current_dir().unwrap().join(path);
+                BenchWhat::Highlight { path: AbsPathBuf::assert(path) }
+            }
+            (None, Some(position), None) => BenchWhat::Complete(position.clone()),
+            (None, None, Some(position)) => BenchWhat::GotoDef(position.clone()),
+            _ => panic!("exactly one of  `--highlight`, `--complete` or `--goto-def` must be set"),
+        }
+    }
+}
diff --git a/crates/rust-analyzer/src/bin/main.rs b/crates/rust-analyzer/src/bin/main.rs
index 89482b952..288847980 100644
--- a/crates/rust-analyzer/src/bin/main.rs
+++ b/crates/rust-analyzer/src/bin/main.rs
@@ -1,14 +1,20 @@
 //! Driver for rust-analyzer.
 //!
 //! Based on cli flags, either spawns an LSP server, or runs a batch analysis
-mod args;
+mod flags;
 mod logger;
-use std::{convert::TryFrom, env, fs, path::PathBuf, process};
+use std::{convert::TryFrom, env, fs, path::Path, process};
 use lsp_server::Connection;
 use project_model::ProjectManifest;
-use rust_analyzer::{cli, config::Config, from_json, lsp_ext::supports_utf8, Result};
+use rust_analyzer::{
+    cli::{self, AnalysisStatsCmd, BenchCmd},
+    config::Config,
+    from_json,
+    lsp_ext::supports_utf8,
+    Result,
+};
 use vfs::AbsPathBuf;
 #[cfg(all(feature = "mimalloc"))]
@@ -28,10 +34,10 @@ fn main() {
 }
 fn try_main() -> Result<()> {
-    let args = args::Args::parse()?;
+    let flags = flags::RustAnalyzer::from_env()?;
    #[cfg(debug_assertions)]
-    if args.wait_dbg || env::var("RA_WAIT_DBG").is_ok() {
+    if flags.wait_dbg || env::var("RA_WAIT_DBG").is_ok() {
        #[allow(unused_mut)]
        let mut d = 4;
        while d == 4 {
@@ -39,35 +45,62 @@ fn try_main() -> Result<()> {
        }
    }
-    setup_logging(args.log_file, args.no_buffering)?;
+    setup_logging(flags.log_file.as_deref(), flags.no_log_buffering)?;
-    match args.command {
+    let verbosity = flags.verbosity();
-        args::Command::RunServer => run_server()?,
-        args::Command::PrintConfigSchema => {
+    match flags.subcommand {
-            println!("{:#}", Config::json_schema());
+        flags::RustAnalyzerCmd::LspServer(cmd) => {
+            if cmd.print_config_schema {
+                println!("{:#}", Config::json_schema());
+                return Ok(());
+            }
+            if cmd.version {
+                println!("rust-analyzer {}", env!("REV"));
+                return Ok(());
+            }
+            if cmd.help {
+                println!("{}", flags::RustAnalyzer::HELP);
+                return Ok(());
+            }
+            run_server()?
        }
-        args::Command::ProcMacro => proc_macro_srv::cli::run()?,
+        flags::RustAnalyzerCmd::ProcMacro(_) => proc_macro_srv::cli::run()?,
+        flags::RustAnalyzerCmd::Parse(cmd) => cli::parse(cmd.no_dump)?,
-        args::Command::Parse { no_dump } => cli::parse(no_dump)?,
+        flags::RustAnalyzerCmd::Symbols(_) => cli::symbols()?,
-        args::Command::Symbols => cli::symbols()?,
+        flags::RustAnalyzerCmd::Highlight(cmd) => cli::highlight(cmd.rainbow)?,
-        args::Command::Highlight { rainbow } => cli::highlight(rainbow)?,
+        flags::RustAnalyzerCmd::AnalysisStats(cmd) => AnalysisStatsCmd {
-        args::Command::AnalysisStats(cmd) => cmd.run(args.verbosity)?,
+            randomize: cmd.randomize,
-        args::Command::Bench(cmd) => cmd.run(args.verbosity)?,
+            parallel: cmd.parallel,
-        args::Command::Diagnostics { path, load_output_dirs, with_proc_macro } => {
+            memory_usage: cmd.memory_usage,
-            cli::diagnostics(path.as_ref(), load_output_dirs, with_proc_macro)?
+            only: cmd.only,
+            with_deps: cmd.with_deps,
+            path: cmd.path,
+            load_output_dirs: cmd.load_output_dirs,
+            with_proc_macro: cmd.with_proc_macro,
        }
-        args::Command::Ssr { rules } => {
+        .run(verbosity)?,
-            cli::apply_ssr_rules(rules)?;
+        flags::RustAnalyzerCmd::AnalysisBench(cmd) => {
+            let what = cmd.what();
+            BenchCmd {
+                memory_usage: cmd.memory_usage,
+                path: cmd.path,
+                load_output_dirs: cmd.load_output_dirs,
+                with_proc_macro: cmd.with_proc_macro,
+                what,
+            }
+            .run(verbosity)?
        }
-        args::Command::StructuredSearch { patterns, debug_snippet } => {
-            cli::search_for_patterns(patterns, debug_snippet)?;
+        flags::RustAnalyzerCmd::Diagnostics(cmd) => {
+            cli::diagnostics(&cmd.path, cmd.load_output_dirs, cmd.with_proc_macro)?
        }
-        args::Command::Version => println!("rust-analyzer {}", env!("REV")),
+        flags::RustAnalyzerCmd::Ssr(cmd) => cli::apply_ssr_rules(cmd.rule)?,
-        args::Command::Help => {}
+        flags::RustAnalyzerCmd::Search(cmd) => cli::search_for_patterns(cmd.pattern, cmd.debug)?,
    }
    Ok(())
 }
-fn setup_logging(log_file: Option<PathBuf>, no_buffering: bool) -> Result<()> {
+fn setup_logging(log_file: Option<&Path>, no_buffering: bool) -> Result<()> {
    env::set_var("RUST_BACKTRACE", "short");
    let log_file = match log_file {
diff --git a/crates/rust-analyzer/src/cli/analysis_bench.rs b/crates/rust-analyzer/src/cli/analysis_bench.rs
index 8991f3bdb..3bd7e678d 100644
--- a/crates/rust-analyzer/src/cli/analysis_bench.rs
+++ b/crates/rust-analyzer/src/cli/analysis_bench.rs
@@ -35,6 +35,7 @@ pub enum BenchWhat {
    GotoDef(Position),
 }
+#[derive(Debug, Clone)]
 pub struct Position {
    pub path: AbsPathBuf,
    pub line: u32,
@@ -68,7 +69,7 @@ impl BenchCmd {
            load_out_dirs_from_check: self.load_output_dirs,
            with_proc_macro: self.with_proc_macro,
        };
-        let (mut host, vfs) =
+        let (mut host, vfs, _proc_macro) =
            load_workspace_at(&self.path, &cargo_config, &load_cargo_config, &|_| {})?;
        eprintln!("{:?}\n", start.elapsed());
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index 9072d8944..ad0759bda 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -64,7 +64,7 @@ impl AnalysisStatsCmd {
            load_out_dirs_from_check: self.load_output_dirs,
            with_proc_macro: self.with_proc_macro,
        };
-        let (host, vfs) =
+        let (host, vfs, _proc_macro) =
            load_workspace_at(&self.path, &cargo_config, &load_cargo_config, &|_| {})?;
        let db = host.raw_database();
        eprintln!("{:<20} {}", "Database loaded:", db_load_sw.elapsed());
diff --git a/crates/rust-analyzer/src/cli/diagnostics.rs b/crates/rust-analyzer/src/cli/diagnostics.rs
index 876f6c44f..8b985716b 100644
--- a/crates/rust-analyzer/src/cli/diagnostics.rs
+++ b/crates/rust-analyzer/src/cli/diagnostics.rs
@@ -35,7 +35,8 @@ pub fn diagnostics(
 ) -> Result<()> {
    let cargo_config = Default::default();
    let load_cargo_config = LoadCargoConfig { load_out_dirs_from_check, with_proc_macro };
-    let (host, _vfs) = load_workspace_at(path, &cargo_config, &load_cargo_config, &|_| {})?;
+    let (host, _vfs, _proc_macro) =
+        load_workspace_at(path, &cargo_config, &load_cargo_config, &|_| {})?;
    let db = host.raw_database();
    let analysis = host.analysis();
diff --git a/crates/rust-analyzer/src/cli/load_cargo.rs b/crates/rust-analyzer/src/cli/load_cargo.rs
index 23442afac..310c36904 100644
--- a/crates/rust-analyzer/src/cli/load_cargo.rs
+++ b/crates/rust-analyzer/src/cli/load_cargo.rs
@@ -23,7 +23,7 @@ pub fn load_workspace_at(
    cargo_config: &CargoConfig,
    load_config: &LoadCargoConfig,
    progress: &dyn Fn(String),
-) -> Result<(AnalysisHost, vfs::Vfs)> {
+) -> Result<(AnalysisHost, vfs::Vfs, Option<ProcMacroClient>)> {
    let root = AbsPathBuf::assert(std::env::current_dir()?.join(root));
    let root = ProjectManifest::discover_single(&root)?;
    let workspace = ProjectWorkspace::load(root, cargo_config, progress)?;
@@ -35,7 +35,7 @@ pub fn load_workspace(
    ws: ProjectWorkspace,
    config: &LoadCargoConfig,
    progress: &dyn Fn(String),
-) -> Result<(AnalysisHost, vfs::Vfs)> {
+) -> Result<(AnalysisHost, vfs::Vfs, Option<ProcMacroClient>)> {
    let (sender, receiver) = unbounded();
    let mut vfs = vfs::Vfs::default();
    let mut loader = {
@@ -80,7 +80,7 @@ pub fn load_workspace(
    log::debug!("crate graph: {:?}", crate_graph);
    let host =
        load_crate_graph(crate_graph, project_folders.source_root_config, &mut vfs, &receiver);
-    Ok((host, vfs))
+    Ok((host, vfs, proc_macro_client))
 }
 fn load_crate_graph(
@@ -138,7 +138,8 @@ mod tests {
        let cargo_config = Default::default();
        let load_cargo_config =
            LoadCargoConfig { load_out_dirs_from_check: false, with_proc_macro: false };
-        let (host, _vfs) = load_workspace_at(path, &cargo_config, &load_cargo_config, &|_| {})?;
+        let (host, _vfs, _proc_macro) =
+            load_workspace_at(path, &cargo_config, &load_cargo_config, &|_| {})?;
        let n_crates = Crate::all(host.raw_database()).len();
        // RA has quite a few crates, but the exact count doesn't matter
diff --git a/crates/rust-analyzer/src/cli/ssr.rs b/crates/rust-analyzer/src/cli/ssr.rs
index 71a8f8fb9..79f426fff 100644
--- a/crates/rust-analyzer/src/cli/ssr.rs
+++ b/crates/rust-analyzer/src/cli/ssr.rs
@@ -11,7 +11,7 @@ pub fn apply_ssr_rules(rules: Vec<SsrRule>) -> Result<()> {
    let cargo_config = Default::default();
    let load_cargo_config =
        LoadCargoConfig { load_out_dirs_from_check: true, with_proc_macro: true };
-    let (host, vfs) =
+    let (host, vfs, _proc_macro) =
        load_workspace_at(&std::env::current_dir()?, &cargo_config, &load_cargo_config, &|_| {})?;
    let db = host.raw_database();
    let mut match_finder = MatchFinder::at_first_file(db)?;
@@ -38,7 +38,7 @@ pub fn search_for_patterns(patterns: Vec<SsrPattern>, debug_snippet: Option<Stri
    let cargo_config = Default::default();
    let load_cargo_config =
        LoadCargoConfig { load_out_dirs_from_check: true, with_proc_macro: true };
-    let (host, _vfs) =
+    let (host, _vfs, _proc_macro) =
        load_workspace_at(&std::env::current_dir()?, &cargo_config, &load_cargo_config, &|_| {})?;
    let db = host.raw_database();
    let mut match_finder = MatchFinder::at_first_file(db)?;
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 556fc2eeb..367136702 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -46,8 +46,8 @@ config_data! {
        cargo_allFeatures: bool          = "false",
        /// List of features to activate.
        cargo_features: Vec<String>      = "[]",
-        /// Run `cargo check` on startup to get the correct value for package
+        /// Run build scripts (`build.rs`) for more precise code analysis.
-        /// OUT_DIRs.
+        cargo_runBuildScripts |
        cargo_loadOutDirsFromCheck: bool = "false",
        /// Do not activate the `default` feature.
        cargo_noDefaultFeatures: bool    = "false",
@@ -167,8 +167,7 @@ config_data! {
        /// Whether to show `can't find Cargo.toml` error message.
        notifications_cargoTomlNotFound: bool      = "true",
-        /// Enable Proc macro support, `#rust-analyzer.cargo.loadOutDirsFromCheck#` must be
+        /// Enable support for procedural macros, implies `#rust-analyzer.cargo.runBuildScripts#`.
-        /// enabled.
        procMacro_enable: bool                     = "false",
        /// Internal config, path to proc-macro server executable (typically,
        /// this is rust-analyzer itself, but we override this in tests).
@@ -480,8 +479,8 @@ impl Config {
    pub fn cargo_autoreload(&self) -> bool {
        self.data.cargo_autoreload
    }
-    pub fn load_out_dirs_from_check(&self) -> bool {
+    pub fn run_build_scripts(&self) -> bool {
-        self.data.cargo_loadOutDirsFromCheck
+        self.data.cargo_runBuildScripts || self.data.procMacro_enable
    }
    pub fn cargo(&self) -> CargoConfig {
        let rustc_source = self.data.rustcSource.as_ref().map(|rustc_src| {
diff --git a/crates/rust-analyzer/src/diagnostics/to_proto.rs b/crates/rust-analyzer/src/diagnostics/to_proto.rs
index 0ed87fe3e..0ad832c0e 100644
--- a/crates/rust-analyzer/src/diagnostics/to_proto.rs
+++ b/crates/rust-analyzer/src/diagnostics/to_proto.rs
@@ -29,7 +29,7 @@ fn diagnostic_severity(
        },
        DiagnosticLevel::Note => lsp_types::DiagnosticSeverity::Information,
        DiagnosticLevel::Help => lsp_types::DiagnosticSeverity::Hint,
-        DiagnosticLevel::Unknown => return None,
+        _ => return None,
    };
    Some(res)
 }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 2829d5970..f0cb309e4 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -312,7 +312,7 @@ impl GlobalState {
                                } else {
                                    assert_eq!(n_done, n_total);
                                    new_status = Status::Ready {
-                                        partial: self.config.load_out_dirs_from_check()
+                                        partial: self.config.run_build_scripts()
                                            && self.workspace_build_data.is_none()
                                            || config_version < self.vfs_config_version,
                                    };
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index c07efa330..aa8504c3d 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -337,7 +337,7 @@ impl GlobalState {
        };
        change.set_crate_graph(crate_graph);
-        if self.config.load_out_dirs_from_check() && workspace_build_data.is_none() {
+        if self.config.run_build_scripts() && workspace_build_data.is_none() {
            let mut collector = BuildDataCollector::default();
            for ws in &workspaces {
                ws.collect_build_data_configs(&mut collector);
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 70cb7fbab..c1ca88df6 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -474,7 +474,7 @@ pub(crate) fn folding_range(
    let kind = match fold.kind {
        FoldKind::Comment => Some(lsp_types::FoldingRangeKind::Comment),
        FoldKind::Imports => Some(lsp_types::FoldingRangeKind::Imports),
-        FoldKind::Mods | FoldKind::Block | FoldKind::ArgList => None,
+        FoldKind::Mods | FoldKind::Block | FoldKind::ArgList | FoldKind::Region => None,
    };
    let range = range(line_index, fold.range);
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index d836c5d1a..9ee3a8586 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 itertools = "0.10.0"
 rowan = "0.12.2"
-rustc_lexer = { version = "708.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer = { version = "709.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 arrayvec = "0.5.1"
 once_cell = "1.3.1"
diff --git a/crates/syntax/src/ast/edit.rs b/crates/syntax/src/ast/edit.rs
index 824ebf41c..0b3b76d4a 100644
--- a/crates/syntax/src/ast/edit.rs
+++ b/crates/syntax/src/ast/edit.rs
@@ -595,11 +595,14 @@ impl ops::Add<u8> for IndentLevel {
 impl IndentLevel {
    pub fn from_node(node: &SyntaxNode) -> IndentLevel {
-        let first_token = match node.first_token() {
+        match node.first_token() {
-            Some(it) => it,
+            Some(it) => Self::from_token(&it),
            None => return IndentLevel(0),
-        };
+        }
-        for ws in prev_tokens(first_token).filter_map(ast::Whitespace::cast) {
+    }
+    pub fn from_token(token: &SyntaxToken) -> IndentLevel {
+        for ws in prev_tokens(token.clone()).filter_map(ast::Whitespace::cast) {
            let text = ws.syntax().text();
            if let Some(pos) = text.rfind('\n') {
                let level = text[pos + 1..].chars().count() / 4;
diff --git a/crates/syntax/src/ast/token_ext.rs b/crates/syntax/src/ast/token_ext.rs
index 044e3e5e8..977eb8181 100644
--- a/crates/syntax/src/ast/token_ext.rs
+++ b/crates/syntax/src/ast/token_ext.rs
@@ -85,8 +85,9 @@ pub enum CommentPlacement {
 }
 impl CommentKind {
-    const BY_PREFIX: [(&'static str, CommentKind); 8] = [
+    const BY_PREFIX: [(&'static str, CommentKind); 9] = [
        ("/**/", CommentKind { shape: CommentShape::Block, doc: None }),
+        ("/***", CommentKind { shape: CommentShape::Block, doc: None }),
        ("////", CommentKind { shape: CommentShape::Line, doc: None }),
        ("///", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Outer) }),
        ("//!", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Inner) }),