40 files changed, 712 insertions, 568 deletions

diff --git a/Cargo.lock b/Cargo.lock
index e40c12a92..ca0311595 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1867,6 +1867,7 @@ name = "vfs"
 version = "0.0.0"
 dependencies = [
  "fst",
+ "indexmap",
  "paths",
  "rustc-hash",
 ]
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index dfc1d8a0c..8d00f7401 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -59,7 +59,7 @@ use hir_ty::{
     traits::FnTrait,
     AliasEq, AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, CanonicalVarKinds, Cast,
     DebruijnIndex, InEnvironment, Interner, QuantifiedWhereClause, Scalar, Solution,
-    SolutionVariables, Substitution, TraitEnvironment, Ty, TyBuilder, TyDefId, TyKind,
+    SolutionVariables, Substitution, TraitEnvironment, Ty, TyBuilder, TyDefId, TyExt, TyKind,
     TyVariableKind, WhereClause,
 };
 use itertools::Itertools;
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index 4ce1c2080..c013e78d9 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -161,14 +161,15 @@ impl SourceAnalyzer {
         db: &dyn HirDatabase,
         field: &ast::RecordExprField,
     ) -> Option<(Field, Option<Local>)> {
-        let expr_id =
-            self.body_source_map.as_ref()?.node_field(InFile::new(self.file_id, field))?;
+        let record_expr = ast::RecordExpr::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
+        let expr = ast::Expr::from(record_expr);
+        let expr_id = self.body_source_map.as_ref()?.node_expr(InFile::new(self.file_id, &expr))?;
 
+        let local_name = field.field_name()?.as_name();
         let local = if field.name_ref().is_some() {
             None
         } else {
-            let local_name = field.field_name()?.as_name();
-            let path = ModPath::from_segments(PathKind::Plain, once(local_name));
+            let path = ModPath::from_segments(PathKind::Plain, once(local_name.clone()));
             match self.resolver.resolve_path_in_value_ns_fully(db.upcast(), &path) {
                 Some(ValueNs::LocalBinding(pat_id)) => {
                     Some(Local { pat_id, parent: self.resolver.body_owner()? })
@@ -176,8 +177,10 @@ impl SourceAnalyzer {
                 _ => None,
             }
         };
-        let struct_field = self.infer.as_ref()?.record_field_resolution(expr_id)?;
-        Some((struct_field.into(), local))
+        let variant = self.infer.as_ref()?.variant_resolution_for_expr(expr_id)?;
+        let variant_data = variant.variant_data(db.upcast());
+        let field = FieldId { parent: variant, local_id: variant_data.field(&local_name)? };
+        Some((field.into(), local))
     }
 
     pub(crate) fn resolve_record_pat_field(
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 63e89a1f4..bfb75a8a5 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -30,6 +30,7 @@ use crate::{
         LabelId, Literal, LogicOp, MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField,
         Statement,
     },
+    intern::Interned,
     item_scope::BuiltinShadowMode,
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
@@ -322,8 +323,10 @@ impl ExprCollector<'_> {
                     Vec::new()
                 };
                 let method_name = e.name_ref().map(|nr| nr.as_name()).unwrap_or_else(Name::missing);
-                let generic_args =
-                    e.generic_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx(), it));
+                let generic_args = e
+                    .generic_arg_list()
+                    .and_then(|it| GenericArgs::from_ast(&self.ctx(), it))
+                    .map(Box::new);
                 self.alloc_expr(
                     Expr::MethodCall { receiver, method_name, args, generic_args },
                     syntax_ptr,
@@ -385,7 +388,7 @@ impl ExprCollector<'_> {
                 self.alloc_expr(Expr::Yield { expr }, syntax_ptr)
             }
             ast::Expr::RecordExpr(e) => {
-                let path = e.path().and_then(|path| self.expander.parse_path(path));
+                let path = e.path().and_then(|path| self.expander.parse_path(path)).map(Box::new);
                 let record_lit = if let Some(nfl) = e.record_expr_field_list() {
                     let fields = nfl
                         .fields()
@@ -430,7 +433,7 @@ impl ExprCollector<'_> {
             }
             ast::Expr::CastExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let type_ref = TypeRef::from_ast_opt(&self.ctx(), e.ty());
+                let type_ref = Interned::new(TypeRef::from_ast_opt(&self.ctx(), e.ty()));
                 self.alloc_expr(Expr::Cast { expr, type_ref }, syntax_ptr)
             }
             ast::Expr::RefExpr(e) => {
@@ -464,13 +467,16 @@ impl ExprCollector<'_> {
                 if let Some(pl) = e.param_list() {
                     for param in pl.params() {
                         let pat = self.collect_pat_opt(param.pat());
-                        let type_ref = param.ty().map(|it| TypeRef::from_ast(&self.ctx(), it));
+                        let type_ref =
+                            param.ty().map(|it| Interned::new(TypeRef::from_ast(&self.ctx(), it)));
                         args.push(pat);
                         arg_types.push(type_ref);
                     }
                 }
-                let ret_type =
-                    e.ret_type().and_then(|r| r.ty()).map(|it| TypeRef::from_ast(&self.ctx(), it));
+                let ret_type = e
+                    .ret_type()
+                    .and_then(|r| r.ty())
+                    .map(|it| Interned::new(TypeRef::from_ast(&self.ctx(), it)));
                 let body = self.collect_expr_opt(e.body());
                 self.alloc_expr(Expr::Lambda { args, arg_types, ret_type, body }, syntax_ptr)
             }
@@ -625,7 +631,8 @@ impl ExprCollector<'_> {
                     return;
                 }
                 let pat = self.collect_pat_opt(stmt.pat());
-                let type_ref = stmt.ty().map(|it| TypeRef::from_ast(&self.ctx(), it));
+                let type_ref =
+                    stmt.ty().map(|it| Interned::new(TypeRef::from_ast(&self.ctx(), it)));
                 let initializer = stmt.initializer().map(|e| self.collect_expr(e));
                 self.statements_in_scope.push(Statement::Let { pat, type_ref, initializer });
             }
@@ -755,7 +762,7 @@ impl ExprCollector<'_> {
                 }
             }
             ast::Pat::TupleStructPat(p) => {
-                let path = p.path().and_then(|path| self.expander.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path)).map(Box::new);
                 let (args, ellipsis) = self.collect_tuple_pat(p.fields());
                 Pat::TupleStruct { path, args, ellipsis }
             }
@@ -765,7 +772,7 @@ impl ExprCollector<'_> {
                 Pat::Ref { pat, mutability }
             }
             ast::Pat::PathPat(p) => {
-                let path = p.path().and_then(|path| self.expander.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path)).map(Box::new);
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
             ast::Pat::OrPat(p) => {
@@ -779,7 +786,7 @@ impl ExprCollector<'_> {
             }
             ast::Pat::WildcardPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
-                let path = p.path().and_then(|path| self.expander.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path)).map(Box::new);
                 let args: Vec<_> = p
                     .record_pat_field_list()
                     .expect("every struct should have a field list")
diff --git a/crates/hir_def/src/expr.rs b/crates/hir_def/src/expr.rs
index 6c7376fad..b4ad984bd 100644
--- a/crates/hir_def/src/expr.rs
+++ b/crates/hir_def/src/expr.rs
@@ -18,6 +18,7 @@ use syntax::ast::RangeOp;
 
 use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt, BuiltinUint},
+    intern::Interned,
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
     BlockId,
@@ -86,7 +87,7 @@ pub enum Expr {
         receiver: ExprId,
         method_name: Name,
         args: Vec<ExprId>,
-        generic_args: Option<GenericArgs>,
+        generic_args: Option<Box<GenericArgs>>,
     },
     Match {
         expr: ExprId,
@@ -106,7 +107,7 @@ pub enum Expr {
         expr: Option<ExprId>,
     },
     RecordLit {
-        path: Option<Path>,
+        path: Option<Box<Path>>,
         fields: Vec<RecordLitField>,
         spread: Option<ExprId>,
     },
@@ -131,7 +132,7 @@ pub enum Expr {
     },
     Cast {
         expr: ExprId,
-        type_ref: TypeRef,
+        type_ref: Interned<TypeRef>,
     },
     Ref {
         expr: ExprId,
@@ -161,8 +162,8 @@ pub enum Expr {
     },
     Lambda {
         args: Vec<PatId>,
-        arg_types: Vec<Option<TypeRef>>,
-        ret_type: Option<TypeRef>,
+        arg_types: Vec<Option<Interned<TypeRef>>>,
+        ret_type: Option<Interned<TypeRef>>,
         body: ExprId,
     },
     Tuple {
@@ -240,7 +241,7 @@ pub struct RecordLitField {
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Statement {
-    Let { pat: PatId, type_ref: Option<TypeRef>, initializer: Option<ExprId> },
+    Let { pat: PatId, type_ref: Option<Interned<TypeRef>>, initializer: Option<ExprId> },
     Expr(ExprId),
 }
 
@@ -412,13 +413,13 @@ pub enum Pat {
     Wild,
     Tuple { args: Vec<PatId>, ellipsis: Option<usize> },
     Or(Vec<PatId>),
-    Record { path: Option<Path>, args: Vec<RecordFieldPat>, ellipsis: bool },
+    Record { path: Option<Box<Path>>, args: Vec<RecordFieldPat>, ellipsis: bool },
     Range { start: ExprId, end: ExprId },
     Slice { prefix: Vec<PatId>, slice: Option<PatId>, suffix: Vec<PatId> },
-    Path(Path),
+    Path(Box<Path>),
     Lit(ExprId),
     Bind { mode: BindingAnnotation, name: Name, subpat: Option<PatId> },
-    TupleStruct { path: Option<Path>, args: Vec<PatId>, ellipsis: Option<usize> },
+    TupleStruct { path: Option<Box<Path>>, args: Vec<PatId>, ellipsis: Option<usize> },
     Ref { pat: PatId, mutability: Mutability },
     Box { inner: PatId },
     ConstBlock(ExprId),
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index be9a5e1a0..abd6c553f 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -56,6 +56,7 @@ use std::{
     sync::Arc,
 };
 
+use adt::VariantData;
 use base_db::{impl_intern_key, salsa, CrateId};
 use hir_expand::{
     ast_id_map::FileAstId,
@@ -442,6 +443,18 @@ pub enum VariantId {
 }
 impl_from!(EnumVariantId, StructId, UnionId for VariantId);
 
+impl VariantId {
+    pub fn variant_data(self, db: &dyn db::DefDatabase) -> Arc<VariantData> {
+        match self {
+            VariantId::StructId(it) => db.struct_data(it).variant_data.clone(),
+            VariantId::UnionId(it) => db.union_data(it).variant_data.clone(),
+            VariantId::EnumVariantId(it) => {
+                db.enum_data(it.parent).variants[it.local_id].variant_data.clone()
+            }
+        }
+    }
+}
+
 trait Intern {
     type ID;
     fn intern(self, db: &dyn db::DefDatabase) -> Self::ID;
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index f9c8328f0..b528ff8ba 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -289,6 +289,12 @@ impl From<Name> for Path {
     }
 }
 
+impl From<Name> for Box<Path> {
+    fn from(name: Name) -> Box<Path> {
+        Box::new(Path::from(name))
+    }
+}
+
 impl From<Name> for ModPath {
     fn from(name: Name) -> ModPath {
         ModPath::from_segments(PathKind::Plain, iter::once(name))
diff --git a/crates/hir_ty/src/builder.rs b/crates/hir_ty/src/builder.rs
index 791915fe0..09512d1ce 100644
--- a/crates/hir_ty/src/builder.rs
+++ b/crates/hir_ty/src/builder.rs
@@ -13,7 +13,7 @@ use smallvec::SmallVec;
 use crate::{
     db::HirDatabase, primitive, to_assoc_type_id, to_chalk_trait_id, utils::generics, Binders,
     CallableSig, FnPointer, FnSig, FnSubst, GenericArg, Interner, ProjectionTy, Substitution,
-    TraitRef, Ty, TyDefId, TyKind, TypeWalk, ValueTyDefId,
+    TraitRef, Ty, TyDefId, TyExt, TyKind, TypeWalk, ValueTyDefId,
 };
 
 /// This is a builder for `Ty` or anything that needs a `Substitution`.
diff --git a/crates/hir_ty/src/chalk_ext.rs b/crates/hir_ty/src/chalk_ext.rs
index 0f4cb43e9..8e8a1aa48 100644
--- a/crates/hir_ty/src/chalk_ext.rs
+++ b/crates/hir_ty/src/chalk_ext.rs
@@ -1,20 +1,243 @@
 //! Various extensions traits for Chalk types.
 
-use hir_def::{AssocContainerId, Lookup, TraitId};
+use chalk_ir::Mutability;
+use hir_def::{
+    type_ref::Rawness, AssocContainerId, FunctionId, GenericDefId, HasModule, Lookup, TraitId,
+};
 
 use crate::{
-    db::HirDatabase, from_assoc_type_id, to_chalk_trait_id, Interner, ProjectionTy, TraitRef, Ty,
-    TyKind,
+    db::HirDatabase, from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id,
+    from_placeholder_idx, to_chalk_trait_id, AdtId, AliasEq, AliasTy, Binders, CallableDefId,
+    CallableSig, ImplTraitId, Interner, Lifetime, ProjectionTy, QuantifiedWhereClause,
+    Substitution, TraitRef, Ty, TyBuilder, TyKind, WhereClause,
 };
 
 pub trait TyExt {
     fn is_unit(&self) -> bool;
+    fn is_never(&self) -> bool;
+    fn is_unknown(&self) -> bool;
+
+    fn as_adt(&self) -> Option<(hir_def::AdtId, &Substitution)>;
+    fn as_tuple(&self) -> Option<&Substitution>;
+    fn as_fn_def(&self, db: &dyn HirDatabase) -> Option<FunctionId>;
+    fn as_reference(&self) -> Option<(&Ty, Lifetime, Mutability)>;
+    fn as_reference_or_ptr(&self) -> Option<(&Ty, Rawness, Mutability)>;
+    fn as_generic_def(&self, db: &dyn HirDatabase) -> Option<GenericDefId>;
+
+    fn callable_def(&self, db: &dyn HirDatabase) -> Option<CallableDefId>;
+    fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig>;
+
+    fn strip_references(&self) -> &Ty;
+
+    /// If this is a `dyn Trait`, returns that trait.
+    fn dyn_trait(&self) -> Option<TraitId>;
+
+    fn impl_trait_bounds(&self, db: &dyn HirDatabase) -> Option<Vec<QuantifiedWhereClause>>;
+    fn associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<TraitId>;
 }
 
 impl TyExt for Ty {
     fn is_unit(&self) -> bool {
         matches!(self.kind(&Interner), TyKind::Tuple(0, _))
     }
+
+    fn is_never(&self) -> bool {
+        matches!(self.kind(&Interner), TyKind::Never)
+    }
+
+    fn is_unknown(&self) -> bool {
+        matches!(self.kind(&Interner), TyKind::Error)
+    }
+
+    fn as_adt(&self) -> Option<(hir_def::AdtId, &Substitution)> {
+        match self.kind(&Interner) {
+            TyKind::Adt(AdtId(adt), parameters) => Some((*adt, parameters)),
+            _ => None,
+        }
+    }
+
+    fn as_tuple(&self) -> Option<&Substitution> {
+        match self.kind(&Interner) {
+            TyKind::Tuple(_, substs) => Some(substs),
+            _ => None,
+        }
+    }
+
+    fn as_fn_def(&self, db: &dyn HirDatabase) -> Option<FunctionId> {
+        if let Some(CallableDefId::FunctionId(func)) = self.callable_def(db) {
+            Some(func)
+        } else {
+            None
+        }
+    }
+    fn as_reference(&self) -> Option<(&Ty, Lifetime, Mutability)> {
+        match self.kind(&Interner) {
+            TyKind::Ref(mutability, lifetime, ty) => Some((ty, *lifetime, *mutability)),
+            _ => None,
+        }
+    }
+
+    fn as_reference_or_ptr(&self) -> Option<(&Ty, Rawness, Mutability)> {
+        match self.kind(&Interner) {
+            TyKind::Ref(mutability, _, ty) => Some((ty, Rawness::Ref, *mutability)),
+            TyKind::Raw(mutability, ty) => Some((ty, Rawness::RawPtr, *mutability)),
+            _ => None,
+        }
+    }
+
+    fn as_generic_def(&self, db: &dyn HirDatabase) -> Option<GenericDefId> {
+        match *self.kind(&Interner) {
+            TyKind::Adt(AdtId(adt), ..) => Some(adt.into()),
+            TyKind::FnDef(callable, ..) => {
+                Some(db.lookup_intern_callable_def(callable.into()).into())
+            }
+            TyKind::AssociatedType(type_alias, ..) => Some(from_assoc_type_id(type_alias).into()),
+            TyKind::Foreign(type_alias, ..) => Some(from_foreign_def_id(type_alias).into()),
+            _ => None,
+        }
+    }
+
+    fn callable_def(&self, db: &dyn HirDatabase) -> Option<CallableDefId> {
+        match self.kind(&Interner) {
+            &TyKind::FnDef(def, ..) => Some(db.lookup_intern_callable_def(def.into())),
+            _ => None,
+        }
+    }
+
+    fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig> {
+        match self.kind(&Interner) {
+            TyKind::Function(fn_ptr) => Some(CallableSig::from_fn_ptr(fn_ptr)),
+            TyKind::FnDef(def, parameters) => {
+                let callable_def = db.lookup_intern_callable_def((*def).into());
+                let sig = db.callable_item_signature(callable_def);
+                Some(sig.substitute(&Interner, &parameters))
+            }
+            TyKind::Closure(.., substs) => {
+                let sig_param = substs.at(&Interner, 0).assert_ty_ref(&Interner);
+                sig_param.callable_sig(db)
+            }
+            _ => None,
+        }
+    }
+
+    fn dyn_trait(&self) -> Option<TraitId> {
+        let trait_ref = match self.kind(&Interner) {
+            TyKind::Dyn(dyn_ty) => dyn_ty.bounds.skip_binders().interned().get(0).and_then(|b| {
+                match b.skip_binders() {
+                    WhereClause::Implemented(trait_ref) => Some(trait_ref),
+                    _ => None,
+                }
+            }),
+            _ => None,
+        }?;
+        Some(from_chalk_trait_id(trait_ref.trait_id))
+    }
+
+    fn strip_references(&self) -> &Ty {
+        let mut t: &Ty = self;
+        while let TyKind::Ref(_mutability, _lifetime, ty) = t.kind(&Interner) {
+            t = ty;
+        }
+        t
+    }
+
+    fn impl_trait_bounds(&self, db: &dyn HirDatabase) -> Option<Vec<QuantifiedWhereClause>> {
+        match self.kind(&Interner) {
+            TyKind::OpaqueType(opaque_ty_id, ..) => {
+                match db.lookup_intern_impl_trait_id((*opaque_ty_id).into()) {
+                    ImplTraitId::AsyncBlockTypeImplTrait(def, _expr) => {
+                        let krate = def.module(db.upcast()).krate();
+                        if let Some(future_trait) = db
+                            .lang_item(krate, "future_trait".into())
+                            .and_then(|item| item.as_trait())
+                        {
+                            // This is only used by type walking.
+                            // Parameters will be walked outside, and projection predicate is not used.
+                            // So just provide the Future trait.
+                            let impl_bound = Binders::empty(
+                                &Interner,
+                                WhereClause::Implemented(TraitRef {
+                                    trait_id: to_chalk_trait_id(future_trait),
+                                    substitution: Substitution::empty(&Interner),
+                                }),
+                            );
+                            Some(vec![impl_bound])
+                        } else {
+                            None
+                        }
+                    }
+                    ImplTraitId::ReturnTypeImplTrait(..) => None,
+                }
+            }
+            TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
+                let predicates = match db.lookup_intern_impl_trait_id(opaque_ty.opaque_ty_id.into())
+                {
+                    ImplTraitId::ReturnTypeImplTrait(func, idx) => {
+                        db.return_type_impl_traits(func).map(|it| {
+                            let data = (*it)
+                                .as_ref()
+                                .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
+                            data.substitute(&Interner, &opaque_ty.substitution)
+                        })
+                    }
+                    // It always has an parameter for Future::Output type.
+                    ImplTraitId::AsyncBlockTypeImplTrait(..) => unreachable!(),
+                };
+
+                predicates.map(|it| it.into_value_and_skipped_binders().0)
+            }
+            TyKind::Placeholder(idx) => {
+                let id = from_placeholder_idx(db, *idx);
+                let generic_params = db.generic_params(id.parent);
+                let param_data = &generic_params.types[id.local_id];
+                match param_data.provenance {
+                    hir_def::generics::TypeParamProvenance::ArgumentImplTrait => {
+                        let substs = TyBuilder::type_params_subst(db, id.parent);
+                        let predicates = db
+                            .generic_predicates(id.parent)
+                            .into_iter()
+                            .map(|pred| pred.clone().substitute(&Interner, &substs))
+                            .filter(|wc| match &wc.skip_binders() {
+                                WhereClause::Implemented(tr) => {
+                                    tr.self_type_parameter(&Interner) == self
+                                }
+                                WhereClause::AliasEq(AliasEq {
+                                    alias: AliasTy::Projection(proj),
+                                    ty: _,
+                                }) => proj.self_type_parameter(&Interner) == self,
+                                _ => false,
+                            })
+                            .collect::<Vec<_>>();
+
+                        Some(predicates)
+                    }
+                    _ => None,
+                }
+            }
+            _ => None,
+        }
+    }
+
+    fn associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<TraitId> {
+        match self.kind(&Interner) {
+            TyKind::AssociatedType(id, ..) => {
+                match from_assoc_type_id(*id).lookup(db.upcast()).container {
+                    AssocContainerId::TraitId(trait_id) => Some(trait_id),
+                    _ => None,
+                }
+            }
+            TyKind::Alias(AliasTy::Projection(projection_ty)) => {
+                match from_assoc_type_id(projection_ty.associated_ty_id)
+                    .lookup(db.upcast())
+                    .container
+                {
+                    AssocContainerId::TraitId(trait_id) => Some(trait_id),
+                    _ => None,
+                }
+            }
+            _ => None,
+        }
+    }
 }
 
 pub trait ProjectionTyExt {
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index d7bf9fdf7..79602c3dd 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -14,7 +14,6 @@ use crate::{
         MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
         MissingPatFields, RemoveThisSemicolon,
     },
-    utils::variant_data,
     AdtId, InferenceResult, Interner, TyExt, TyKind,
 };
 
@@ -104,7 +103,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
             let root = source_ptr.file_syntax(db.upcast());
             if let ast::Expr::RecordExpr(record_expr) = &source_ptr.value.to_node(&root) {
                 if let Some(_) = record_expr.record_expr_field_list() {
-                    let variant_data = variant_data(db.upcast(), variant_def);
+                    let variant_data = variant_def.variant_data(db.upcast());
                     let missed_fields = missed_fields
                         .into_iter()
                         .map(|idx| variant_data.fields()[idx].name.clone())
@@ -135,7 +134,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 let root = source_ptr.file_syntax(db.upcast());
                 if let ast::Pat::RecordPat(record_pat) = expr.to_node(&root) {
                     if let Some(_) = record_pat.record_pat_field_list() {
-                        let variant_data = variant_data(db.upcast(), variant_def);
+                        let variant_data = variant_def.variant_data(db.upcast());
                         let missed_fields = missed_fields
                             .into_iter()
                             .map(|idx| variant_data.fields()[idx].name.clone())
@@ -453,7 +452,7 @@ pub fn record_literal_missing_fields(
         return None;
     }
 
-    let variant_data = variant_data(db.upcast(), variant_def);
+    let variant_data = variant_def.variant_data(db.upcast());
 
     let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
     let missed_fields: Vec<LocalFieldId> = variant_data
@@ -483,7 +482,7 @@ pub fn record_pattern_missing_fields(
         return None;
     }
 
-    let variant_data = variant_data(db.upcast(), variant_def);
+    let variant_data = variant_def.variant_data(db.upcast());
 
     let specified_fields: FxHashSet<_> = fields.iter().map(|f| &f.name).collect();
     let missed_fields: Vec<LocalFieldId> = variant_data
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index 34291578a..e9762622f 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -227,7 +227,7 @@ use hir_def::{
 use la_arena::Idx;
 use smallvec::{smallvec, SmallVec};
 
-use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, TyKind};
+use crate::{db::HirDatabase, AdtId, InferenceResult, Interner, TyExt, TyKind};
 
 #[derive(Debug, Clone, Copy)]
 /// Either a pattern from the source code being analyzed, represented as
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index b5efe9df5..ed97dc0e3 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -11,7 +11,9 @@ use hir_def::{
 };
 use hir_expand::diagnostics::DiagnosticSink;
 
-use crate::{db::HirDatabase, diagnostics::MissingUnsafe, InferenceResult, Interner, TyKind};
+use crate::{
+    db::HirDatabase, diagnostics::MissingUnsafe, InferenceResult, Interner, TyExt, TyKind,
+};
 
 pub(super) struct UnsafeValidator<'a, 'b: 'a> {
     owner: DefWithBodyId,
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 1c3faf5cb..c63878e7a 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -42,7 +42,7 @@ use super::{
 };
 use crate::{
     db::HirDatabase, infer::diagnostics::InferenceDiagnostic, lower::ImplTraitLoweringMode,
-    to_assoc_type_id, AliasEq, AliasTy, Interner, TyBuilder, TyKind,
+    to_assoc_type_id, AliasEq, AliasTy, Interner, TyBuilder, TyExt, TyKind,
 };
 
 // This lint has a false positive here. See the link below for details.
@@ -131,8 +131,6 @@ pub struct InferenceResult {
     method_resolutions: FxHashMap<ExprId, FunctionId>,
     /// For each field access expr, records the field it resolves to.
     field_resolutions: FxHashMap<ExprId, FieldId>,
-    /// For each field in record literal, records the field it resolves to.
-    record_field_resolutions: FxHashMap<ExprId, FieldId>,
     record_pat_field_resolutions: FxHashMap<PatId, FieldId>,
     /// For each struct literal, records the variant it resolves to.
     variant_resolutions: FxHashMap<ExprOrPatId, VariantId>,
@@ -153,9 +151,6 @@ impl InferenceResult {
     pub fn field_resolution(&self, expr: ExprId) -> Option<FieldId> {
         self.field_resolutions.get(&expr).copied()
     }
-    pub fn record_field_resolution(&self, expr: ExprId) -> Option<FieldId> {
-        self.record_field_resolutions.get(&expr).copied()
-    }
     pub fn record_pat_field_resolution(&self, pat: PatId) -> Option<FieldId> {
         self.record_pat_field_resolutions.get(&pat).copied()
     }
diff --git a/crates/hir_ty/src/infer/coerce.rs b/crates/hir_ty/src/infer/coerce.rs
index d6c48870a..159a53a63 100644
--- a/crates/hir_ty/src/infer/coerce.rs
+++ b/crates/hir_ty/src/infer/coerce.rs
@@ -7,7 +7,7 @@
 use chalk_ir::{cast::Cast, Mutability, TyVariableKind};
 use hir_def::lang_item::LangItemTarget;
 
-use crate::{autoderef, Interner, Solution, Ty, TyBuilder, TyKind};
+use crate::{autoderef, Interner, Solution, Ty, TyBuilder, TyExt, TyKind};
 
 use super::{InEnvironment, InferenceContext};
 
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 53d94fd0d..9ab0fa212 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -21,9 +21,10 @@ use crate::{
     primitive::{self, UintTy},
     static_lifetime, to_chalk_trait_id,
     traits::{chalk::from_chalk, FnTrait},
-    utils::{generics, variant_data, Generics},
+    utils::{generics, Generics},
     AdtId, Binders, CallableDefId, FnPointer, FnSig, FnSubst, InEnvironment, Interner,
-    ProjectionTyExt, Rawness, Scalar, Substitution, TraitRef, Ty, TyBuilder, TyKind, TypeWalk,
+    ProjectionTyExt, Rawness, Scalar, Substitution, TraitRef, Ty, TyBuilder, TyExt, TyKind,
+    TypeWalk,
 };
 
 use super::{
@@ -317,7 +318,13 @@ impl<'a> InferenceContext<'a> {
                 self.normalize_associated_types_in(ret_ty)
             }
             Expr::MethodCall { receiver, args, method_name, generic_args } => self
-                .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
+                .infer_method_call(
+                    tgt_expr,
+                    *receiver,
+                    &args,
+                    &method_name,
+                    generic_args.as_deref(),
+                ),
             Expr::Match { expr, arms } => {
                 let input_ty = self.infer_expr(*expr, &Expectation::none());
 
@@ -398,7 +405,7 @@ impl<'a> InferenceContext<'a> {
                 TyKind::Never.intern(&Interner)
             }
             Expr::RecordLit { path, fields, spread } => {
-                let (ty, def_id) = self.resolve_variant(path.as_ref());
+                let (ty, def_id) = self.resolve_variant(path.as_deref());
                 if let Some(variant) = def_id {
                     self.write_variant_resolution(tgt_expr.into(), variant);
                 }
@@ -407,7 +414,7 @@ impl<'a> InferenceContext<'a> {
 
                 let substs = ty.substs().cloned().unwrap_or_else(|| Substitution::empty(&Interner));
                 let field_types = def_id.map(|it| self.db.field_types(it)).unwrap_or_default();
-                let variant_data = def_id.map(|it| variant_data(self.db.upcast(), it));
+                let variant_data = def_id.map(|it| it.variant_data(self.db.upcast()));
                 for field in fields.iter() {
                     let field_def =
                         variant_data.as_ref().and_then(|it| match it.field(&field.name) {
@@ -419,9 +426,6 @@ impl<'a> InferenceContext<'a> {
                                 None
                             }
                         });
-                    if let Some(field_def) = field_def {
-                        self.result.record_field_resolutions.insert(field.expr, field_def);
-                    }
                     let field_ty = field_def.map_or(self.err_ty(), |it| {
                         field_types[it.local_id].clone().substitute(&Interner, &substs)
                     });
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index c1d7a6b76..942f70edf 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -13,8 +13,8 @@ use hir_expand::name::Name;
 
 use super::{BindingMode, Expectation, InferenceContext};
 use crate::{
-    lower::lower_to_chalk_mutability, static_lifetime, utils::variant_data, Interner, Substitution,
-    Ty, TyBuilder, TyKind,
+    lower::lower_to_chalk_mutability, static_lifetime, Interner, Substitution, Ty, TyBuilder,
+    TyExt, TyKind,
 };
 
 impl<'a> InferenceContext<'a> {
@@ -28,7 +28,7 @@ impl<'a> InferenceContext<'a> {
         ellipsis: Option<usize>,
     ) -> Ty {
         let (ty, def) = self.resolve_variant(path);
-        let var_data = def.map(|it| variant_data(self.db.upcast(), it));
+        let var_data = def.map(|it| it.variant_data(self.db.upcast()));
         if let Some(variant) = def {
             self.write_variant_resolution(id.into(), variant);
         }
@@ -68,7 +68,7 @@ impl<'a> InferenceContext<'a> {
         id: PatId,
     ) -> Ty {
         let (ty, def) = self.resolve_variant(path);
-        let var_data = def.map(|it| variant_data(self.db.upcast(), it));
+        let var_data = def.map(|it| it.variant_data(self.db.upcast()));
         if let Some(variant) = def {
             self.write_variant_resolution(id.into(), variant);
         }
@@ -174,7 +174,7 @@ impl<'a> InferenceContext<'a> {
                 TyKind::Ref(mutability, static_lifetime(), subty).intern(&Interner)
             }
             Pat::TupleStruct { path: p, args: subpats, ellipsis } => self.infer_tuple_struct_pat(
-                p.as_ref(),
+                p.as_deref(),
                 subpats,
                 expected,
                 default_bm,
@@ -182,7 +182,7 @@ impl<'a> InferenceContext<'a> {
                 *ellipsis,
             ),
             Pat::Record { path: p, args: fields, ellipsis: _ } => {
-                self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
+                self.infer_record_pat(p.as_deref(), fields, expected, default_bm, pat)
             }
             Pat::Path(path) => {
                 // FIXME use correct resolver for the surrounding expression
diff --git a/crates/hir_ty/src/infer/path.rs b/crates/hir_ty/src/infer/path.rs
index 14f705173..b19d67bb1 100644
--- a/crates/hir_ty/src/infer/path.rs
+++ b/crates/hir_ty/src/infer/path.rs
@@ -10,7 +10,9 @@ use hir_def::{
 };
 use hir_expand::name::Name;
 
-use crate::{method_resolution, Interner, Substitution, Ty, TyBuilder, TyKind, ValueTyDefId};
+use crate::{
+    method_resolution, Interner, Substitution, Ty, TyBuilder, TyExt, TyKind, ValueTyDefId,
+};
 
 use super::{ExprOrPatId, InferenceContext, TraitRef};
 
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index a2a5bcc07..f5b658cba 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -30,13 +30,11 @@ mod test_db;
 
 use std::sync::Arc;
 
-use chalk_ir::UintTy;
-use itertools::Itertools;
-
 use base_db::salsa;
+use chalk_ir::UintTy;
 use hir_def::{
-    expr::ExprId, type_ref::Rawness, AssocContainerId, ConstParamId, FunctionId, GenericDefId,
-    HasModule, LifetimeParamId, Lookup, TraitId, TypeAliasId, TypeParamId,
+    expr::ExprId, type_ref::Rawness, ConstParamId, LifetimeParamId, TraitId, TypeAliasId,
+    TypeParamId,
 };
 
 use crate::{db::HirDatabase, display::HirDisplay, utils::generics};
@@ -171,65 +169,6 @@ impl CallableSig {
 }
 
 impl Ty {
-    pub fn as_reference(&self) -> Option<(&Ty, Lifetime, Mutability)> {
-        match self.kind(&Interner) {
-            TyKind::Ref(mutability, lifetime, ty) => Some((ty, *lifetime, *mutability)),
-            _ => None,
-        }
-    }
-
-    pub fn as_reference_or_ptr(&self) -> Option<(&Ty, Rawness, Mutability)> {
-        match self.kind(&Interner) {
-            TyKind::Ref(mutability, _, ty) => Some((ty, Rawness::Ref, *mutability)),
-            TyKind::Raw(mutability, ty) => Some((ty, Rawness::RawPtr, *mutability)),
-            _ => None,
-        }
-    }
-
-    pub fn strip_references(&self) -> &Ty {
-        let mut t: &Ty = self;
-
-        while let TyKind::Ref(_mutability, _lifetime, ty) = t.kind(&Interner) {
-            t = ty;
-        }
-
-        t
-    }
-
-    pub fn as_adt(&self) -> Option<(hir_def::AdtId, &Substitution)> {
-        match self.kind(&Interner) {
-            TyKind::Adt(AdtId(adt), parameters) => Some((*adt, parameters)),
-            _ => None,
-        }
-    }
-
-    pub fn as_tuple(&self) -> Option<&Substitution> {
-        match self.kind(&Interner) {
-            TyKind::Tuple(_, substs) => Some(substs),
-            _ => None,
-        }
-    }
-
-    pub fn as_generic_def(&self, db: &dyn HirDatabase) -> Option<GenericDefId> {
-        match *self.kind(&Interner) {
-            TyKind::Adt(AdtId(adt), ..) => Some(adt.into()),
-            TyKind::FnDef(callable, ..) => {
-                Some(db.lookup_intern_callable_def(callable.into()).into())
-            }
-            TyKind::AssociatedType(type_alias, ..) => Some(from_assoc_type_id(type_alias).into()),
-            TyKind::Foreign(type_alias, ..) => Some(from_foreign_def_id(type_alias).into()),
-            _ => None,
-        }
-    }
-
-    pub fn is_never(&self) -> bool {
-        matches!(self.kind(&Interner), TyKind::Never)
-    }
-
-    pub fn is_unknown(&self) -> bool {
-        matches!(self.kind(&Interner), TyKind::Error)
-    }
-
     pub fn equals_ctor(&self, other: &Ty) -> bool {
         match (self.kind(&Interner), other.kind(&Interner)) {
             (TyKind::Adt(adt, ..), TyKind::Adt(adt2, ..)) => adt == adt2,
@@ -260,24 +199,6 @@ impl Ty {
         }
     }
 
-    /// If this is a `dyn Trait` type, this returns the `Trait` part.
-    fn dyn_trait_ref(&self) -> Option<&TraitRef> {
-        match self.kind(&Interner) {
-            TyKind::Dyn(dyn_ty) => dyn_ty.bounds.skip_binders().interned().get(0).and_then(|b| {
-                match b.skip_binders() {
-                    WhereClause::Implemented(trait_ref) => Some(trait_ref),
-                    _ => None,
-                }
-            }),
-            _ => None,
-        }
-    }
-
-    /// If this is a `dyn Trait`, returns that trait.
-    pub fn dyn_trait(&self) -> Option<TraitId> {
-        self.dyn_trait_ref().map(|it| it.trait_id).map(from_chalk_trait_id)
-    }
-
     fn builtin_deref(&self) -> Option<Ty> {
         match self.kind(&Interner) {
             TyKind::Ref(.., ty) => Some(ty.clone()),
@@ -286,37 +207,6 @@ impl Ty {
         }
     }
 
-    pub fn callable_def(&self, db: &dyn HirDatabase) -> Option<CallableDefId> {
-        match self.kind(&Interner) {
-            &TyKind::FnDef(def, ..) => Some(db.lookup_intern_callable_def(def.into())),
-            _ => None,
-        }
-    }
-
-    pub fn as_fn_def(&self, db: &dyn HirDatabase) -> Option<FunctionId> {
-        if let Some(CallableDefId::FunctionId(func)) = self.callable_def(db) {
-            Some(func)
-        } else {
-            None
-        }
-    }
-
-    pub fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig> {
-        match self.kind(&Interner) {
-            TyKind::Function(fn_ptr) => Some(CallableSig::from_fn_ptr(fn_ptr)),
-            TyKind::FnDef(def, parameters) => {
-                let callable_def = db.lookup_intern_callable_def((*def).into());
-                let sig = db.callable_item_signature(callable_def);
-                Some(sig.substitute(&Interner, &parameters))
-            }
-            TyKind::Closure(.., substs) => {
-                let sig_param = substs.at(&Interner, 0).assert_ty_ref(&Interner);
-                sig_param.callable_sig(db)
-            }
-            _ => None,
-        }
-    }
-
     /// Returns the type parameters of this type if it has some (i.e. is an ADT
     /// or function); so if `self` is `Option<u32>`, this returns the `u32`.
     pub fn substs(&self) -> Option<&Substitution> {
@@ -344,104 +234,6 @@ impl Ty {
             _ => None,
         }
     }
-
-    pub fn impl_trait_bounds(&self, db: &dyn HirDatabase) -> Option<Vec<QuantifiedWhereClause>> {
-        match self.kind(&Interner) {
-            TyKind::OpaqueType(opaque_ty_id, ..) => {
-                match db.lookup_intern_impl_trait_id((*opaque_ty_id).into()) {
-                    ImplTraitId::AsyncBlockTypeImplTrait(def, _expr) => {
-                        let krate = def.module(db.upcast()).krate();
-                        if let Some(future_trait) = db
-                            .lang_item(krate, "future_trait".into())
-                            .and_then(|item| item.as_trait())
-                        {
-                            // This is only used by type walking.
-                            // Parameters will be walked outside, and projection predicate is not used.
-                            // So just provide the Future trait.
-                            let impl_bound = Binders::empty(
-                                &Interner,
-                                WhereClause::Implemented(TraitRef {
-                                    trait_id: to_chalk_trait_id(future_trait),
-                                    substitution: Substitution::empty(&Interner),
-                                }),
-                            );
-                            Some(vec![impl_bound])
-                        } else {
-                            None
-                        }
-                    }
-                    ImplTraitId::ReturnTypeImplTrait(..) => None,
-                }
-            }
-            TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
-                let predicates = match db.lookup_intern_impl_trait_id(opaque_ty.opaque_ty_id.into())
-                {
-                    ImplTraitId::ReturnTypeImplTrait(func, idx) => {
-                        db.return_type_impl_traits(func).map(|it| {
-                            let data = (*it)
-                                .as_ref()
-                                .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
-                            data.substitute(&Interner, &opaque_ty.substitution)
-                        })
-                    }
-                    // It always has an parameter for Future::Output type.
-                    ImplTraitId::AsyncBlockTypeImplTrait(..) => unreachable!(),
-                };
-
-                predicates.map(|it| it.into_value_and_skipped_binders().0)
-            }
-            TyKind::Placeholder(idx) => {
-                let id = from_placeholder_idx(db, *idx);
-                let generic_params = db.generic_params(id.parent);
-                let param_data = &generic_params.types[id.local_id];
-                match param_data.provenance {
-                    hir_def::generics::TypeParamProvenance::ArgumentImplTrait => {
-                        let substs = TyBuilder::type_params_subst(db, id.parent);
-                        let predicates = db
-                            .generic_predicates(id.parent)
-                            .into_iter()
-                            .map(|pred| pred.clone().substitute(&Interner, &substs))
-                            .filter(|wc| match &wc.skip_binders() {
-                                WhereClause::Implemented(tr) => {
-                                    tr.self_type_parameter(&Interner) == self
-                                }
-                                WhereClause::AliasEq(AliasEq {
-                                    alias: AliasTy::Projection(proj),
-                                    ty: _,
-                                }) => proj.self_type_parameter(&Interner) == self,
-                                _ => false,
-                            })
-                            .collect_vec();
-
-                        Some(predicates)
-                    }
-                    _ => None,
-                }
-            }
-            _ => None,
-        }
-    }
-
-    pub fn associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<TraitId> {
-        match self.kind(&Interner) {
-            TyKind::AssociatedType(id, ..) => {
-                match from_assoc_type_id(*id).lookup(db.upcast()).container {
-                    AssocContainerId::TraitId(trait_id) => Some(trait_id),
-                    _ => None,
-                }
-            }
-            TyKind::Alias(AliasTy::Projection(projection_ty)) => {
-                match from_assoc_type_id(projection_ty.associated_ty_id)
-                    .lookup(db.upcast())
-                    .container
-                {
-                    AssocContainerId::TraitId(trait_id) => Some(trait_id),
-                    _ => None,
-                }
-            }
-            _ => None,
-        }
-    }
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 8be1bcddb..4ca6aa538 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -30,8 +30,7 @@ use crate::{
     dummy_usize_const, static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
     traits::chalk::{Interner, ToChalk},
     utils::{
-        all_super_trait_refs, associated_type_by_name_including_super_traits, generics,
-        variant_data, Generics,
+        all_super_trait_refs, associated_type_by_name_including_super_traits, generics, Generics,
     },
     AliasEq, AliasTy, Binders, BoundVar, CallableSig, DebruijnIndex, DynTy, FnPointer, FnSig,
     FnSubst, ImplTraitId, OpaqueTy, PolyFnSig, ProjectionTy, QuantifiedWhereClause,
@@ -879,7 +878,7 @@ pub(crate) fn field_types_query(
     db: &dyn HirDatabase,
     variant_id: VariantId,
 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
-    let var_data = variant_data(db.upcast(), variant_id);
+    let var_data = variant_id.variant_data(db.upcast());
     let (resolver, def): (_, GenericDefId) = match variant_id {
         VariantId::StructId(it) => (it.resolver(db.upcast()), it.into()),
         VariantId::UnionId(it) => (it.resolver(db.upcast()), it.into()),
diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs
index 5042bfbca..ee725fd46 100644
--- a/crates/hir_ty/src/method_resolution.rs
+++ b/crates/hir_ty/src/method_resolution.rs
@@ -22,7 +22,7 @@ use crate::{
     static_lifetime,
     utils::all_super_traits,
     AdtId, Canonical, CanonicalVarKinds, DebruijnIndex, FnPointer, FnSig, ForeignDefId,
-    InEnvironment, Interner, Scalar, Substitution, TraitEnvironment, Ty, TyBuilder, TyKind,
+    InEnvironment, Interner, Scalar, Substitution, TraitEnvironment, Ty, TyBuilder, TyExt, TyKind,
     TypeWalk,
 };
 
diff --git a/crates/hir_ty/src/traits/chalk.rs b/crates/hir_ty/src/traits/chalk.rs
index 5a8b5cd86..f03b92422 100644
--- a/crates/hir_ty/src/traits/chalk.rs
+++ b/crates/hir_ty/src/traits/chalk.rs
@@ -22,7 +22,7 @@ use crate::{
     to_assoc_type_id, to_chalk_trait_id,
     utils::generics,
     AliasEq, AliasTy, BoundVar, CallableDefId, DebruijnIndex, FnDefId, ProjectionTy, Substitution,
-    TraitRef, Ty, TyBuilder, TyKind, WhereClause,
+    TraitRef, Ty, TyBuilder, TyExt, TyKind, WhereClause,
 };
 use mapping::{
     convert_where_clauses, generic_predicate_to_inline_bound, make_binders, TypeAliasAsValue,
diff --git a/crates/hir_ty/src/utils.rs b/crates/hir_ty/src/utils.rs
index d11708299..0a424f607 100644
--- a/crates/hir_ty/src/utils.rs
+++ b/crates/hir_ty/src/utils.rs
@@ -4,7 +4,6 @@ use std::sync::Arc;
 
 use chalk_ir::{BoundVar, DebruijnIndex};
 use hir_def::{
-    adt::VariantData,
     db::DefDatabase,
     generics::{
         GenericParams, TypeParamData, TypeParamProvenance, WherePredicate, WherePredicateTypeTarget,
@@ -13,7 +12,7 @@ use hir_def::{
     path::Path,
     resolver::{HasResolver, TypeNs},
     type_ref::TypeRef,
-    AssocContainerId, GenericDefId, Lookup, TraitId, TypeAliasId, TypeParamId, VariantId,
+    AssocContainerId, GenericDefId, Lookup, TraitId, TypeAliasId, TypeParamId,
 };
 use hir_expand::name::{name, Name};
 
@@ -136,16 +135,6 @@ pub(super) fn associated_type_by_name_including_super_traits(
     })
 }
 
-pub(super) fn variant_data(db: &dyn DefDatabase, var: VariantId) -> Arc<VariantData> {
-    match var {
-        VariantId::StructId(it) => db.struct_data(it).variant_data.clone(),
-        VariantId::UnionId(it) => db.union_data(it).variant_data.clone(),
-        VariantId::EnumVariantId(it) => {
-            db.enum_data(it.parent).variants[it.local_id].variant_data.clone()
-        }
-    }
-}
-
 /// Helper for mutating `Arc<[T]>` (i.e. `Arc::make_mut` for Arc slices).
 /// The underlying values are cloned if there are other strong references.
 pub(crate) fn make_mut_slice<T: Clone>(a: &mut Arc<[T]>) -> &mut [T] {
diff --git a/crates/paths/src/lib.rs b/crates/paths/src/lib.rs
index 22011cb33..f09ad37e3 100644
--- a/crates/paths/src/lib.rs
+++ b/crates/paths/src/lib.rs
@@ -1,6 +1,7 @@
 //! Thin wrappers around `std::path`, distinguishing between absolute and
 //! relative paths.
 use std::{
+    borrow::Borrow,
     convert::{TryFrom, TryInto},
     ops,
     path::{Component, Path, PathBuf},
@@ -35,6 +36,12 @@ impl AsRef<AbsPath> for AbsPathBuf {
     }
 }
 
+impl Borrow<AbsPath> for AbsPathBuf {
+    fn borrow(&self) -> &AbsPath {
+        self.as_path()
+    }
+}
+
 impl TryFrom<PathBuf> for AbsPathBuf {
     type Error = PathBuf;
     fn try_from(path_buf: PathBuf) -> Result<AbsPathBuf, PathBuf> {
diff --git a/crates/project_model/src/build_data.rs b/crates/project_model/src/build_data.rs
index f7050be4e..0d4d39fef 100644
--- a/crates/project_model/src/build_data.rs
+++ b/crates/project_model/src/build_data.rs
@@ -13,12 +13,12 @@ use cargo_metadata::{BuildScript, Message};
 use itertools::Itertools;
 use paths::{AbsPath, AbsPathBuf};
 use rustc_hash::FxHashMap;
-use stdx::JodChild;
+use stdx::{format_to, JodChild};
 
 use crate::{cfg_flag::CfgFlag, CargoConfig};
 
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
-pub(crate) struct BuildData {
+pub(crate) struct PackageBuildData {
     /// List of config flags defined by this package's build script
     pub(crate) cfgs: Vec<CfgFlag>,
     /// List of cargo-related environment variables with their value
@@ -32,6 +32,17 @@ pub(crate) struct BuildData {
     pub(crate) proc_macro_dylib_path: Option<AbsPathBuf>,
 }
 
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
+pub(crate) struct WorkspaceBuildData {
+    per_package: FxHashMap<String, PackageBuildData>,
+    error: Option<String>,
+}
+
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
+pub struct BuildDataResult {
+    per_workspace: FxHashMap<AbsPathBuf, WorkspaceBuildData>,
+}
+
 #[derive(Clone, Debug)]
 pub(crate) struct BuildDataConfig {
     cargo_toml: AbsPathBuf,
@@ -52,13 +63,6 @@ pub struct BuildDataCollector {
     configs: FxHashMap<AbsPathBuf, BuildDataConfig>,
 }
 
-#[derive(Debug, Default, PartialEq, Eq)]
-pub struct BuildDataResult {
-    data: FxHashMap<AbsPathBuf, BuildDataMap>,
-}
-
-pub(crate) type BuildDataMap = FxHashMap<String, BuildData>;
-
 impl BuildDataCollector {
     pub(crate) fn add_config(&mut self, workspace_root: &AbsPath, config: BuildDataConfig) {
         self.configs.insert(workspace_root.to_path_buf(), config);
@@ -67,7 +71,7 @@ impl BuildDataCollector {
     pub fn collect(&mut self, progress: &dyn Fn(String)) -> Result<BuildDataResult> {
         let mut res = BuildDataResult::default();
         for (path, config) in self.configs.iter() {
-            res.data.insert(
+            res.per_workspace.insert(
                 path.clone(),
                 collect_from_workspace(
                     &config.cargo_toml,
@@ -81,9 +85,28 @@ impl BuildDataCollector {
     }
 }
 
+impl WorkspaceBuildData {
+    pub(crate) fn get(&self, package_id: &str) -> Option<&PackageBuildData> {
+        self.per_package.get(package_id)
+    }
+}
+
 impl BuildDataResult {
-    pub(crate) fn get(&self, root: &AbsPath) -> Option<&BuildDataMap> {
-        self.data.get(&root.to_path_buf())
+    pub(crate) fn get(&self, workspace_root: &AbsPath) -> Option<&WorkspaceBuildData> {
+        self.per_workspace.get(workspace_root)
+    }
+    pub fn error(&self) -> Option<String> {
+        let mut buf = String::new();
+        for (_workspace_root, build_data) in &self.per_workspace {
+            if let Some(err) = &build_data.error {
+                format_to!(buf, "cargo check failed:\n{}", err);
+            }
+        }
+        if buf.is_empty() {
+            return None;
+        }
+
+        Some(buf)
     }
 }
 
@@ -102,7 +125,7 @@ fn collect_from_workspace(
     cargo_features: &CargoConfig,
     packages: &Vec<cargo_metadata::Package>,
     progress: &dyn Fn(String),
-) -> Result<BuildDataMap> {
+) -> Result<WorkspaceBuildData> {
     let mut cmd = Command::new(toolchain::cargo());
     cmd.args(&["check", "--workspace", "--message-format=json", "--manifest-path"])
         .arg(cargo_toml.as_ref());
@@ -130,13 +153,13 @@ fn collect_from_workspace(
         }
     }
 
-    cmd.stdout(Stdio::piped()).stderr(Stdio::null()).stdin(Stdio::null());
+    cmd.stdout(Stdio::piped()).stderr(Stdio::piped()).stdin(Stdio::null());
 
     let mut child = cmd.spawn().map(JodChild)?;
     let child_stdout = child.stdout.take().unwrap();
     let stdout = BufReader::new(child_stdout);
 
-    let mut res = BuildDataMap::default();
+    let mut res = WorkspaceBuildData::default();
     for message in cargo_metadata::Message::parse_stream(stdout).flatten() {
         match message {
             Message::BuildScriptExecuted(BuildScript {
@@ -154,16 +177,17 @@ fn collect_from_workspace(
                     }
                     acc
                 };
-                let res = res.entry(package_id.repr.clone()).or_default();
+                let package_build_data =
+                    res.per_package.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.as_str().is_empty() {
                     let out_dir = AbsPathBuf::assert(PathBuf::from(out_dir.into_os_string()));
-                    res.out_dir = Some(out_dir);
-                    res.cfgs = cfgs;
+                    package_build_data.out_dir = Some(out_dir);
+                    package_build_data.cfgs = cfgs;
                 }
 
-                res.envs = env;
+                package_build_data.envs = env;
             }
             Message::CompilerArtifact(message) => {
                 progress(format!("metadata {}", message.target.name));
@@ -173,8 +197,9 @@ fn collect_from_workspace(
                     // Skip rmeta file
                     if let Some(filename) = message.filenames.iter().find(|name| is_dylib(name)) {
                         let filename = AbsPathBuf::assert(PathBuf::from(&filename));
-                        let res = res.entry(package_id.repr.clone()).or_default();
-                        res.proc_macro_dylib_path = Some(filename);
+                        let package_build_data =
+                            res.per_package.entry(package_id.repr.clone()).or_default();
+                        package_build_data.proc_macro_dylib_path = Some(filename);
                     }
                 }
             }
@@ -188,16 +213,25 @@ fn collect_from_workspace(
     }
 
     for package in packages {
-        let build_data = res.entry(package.id.repr.clone()).or_default();
-        inject_cargo_env(package, build_data);
-        if let Some(out_dir) = &build_data.out_dir {
+        let package_build_data = res.per_package.entry(package.id.repr.clone()).or_default();
+        inject_cargo_env(package, package_build_data);
+        if let Some(out_dir) = &package_build_data.out_dir {
             // NOTE: cargo and rustc seem to hide non-UTF-8 strings from env! and option_env!()
             if let Some(out_dir) = out_dir.to_str().map(|s| s.to_owned()) {
-                build_data.envs.push(("OUT_DIR".to_string(), out_dir));
+                package_build_data.envs.push(("OUT_DIR".to_string(), out_dir));
             }
         }
     }
 
+    let output = child.into_inner().wait_with_output()?;
+    if !output.status.success() {
+        let mut stderr = String::from_utf8(output.stderr).unwrap_or_default();
+        if stderr.is_empty() {
+            stderr = "cargo check failed".to_string();
+        }
+        res.error = Some(stderr)
+    }
+
     Ok(res)
 }
 
@@ -212,7 +246,7 @@ fn is_dylib(path: &Utf8Path) -> bool {
 /// Recreates the compile-time environment variables that Cargo sets.
 ///
 /// Should be synced with <https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates>
-fn inject_cargo_env(package: &cargo_metadata::Package, build_data: &mut BuildData) {
+fn inject_cargo_env(package: &cargo_metadata::Package, build_data: &mut PackageBuildData) {
     let env = &mut build_data.envs;
 
     // FIXME: Missing variables:
diff --git a/crates/project_model/src/workspace.rs b/crates/project_model/src/workspace.rs
index 1b53fcc30..2fcd0f8fa 100644
--- a/crates/project_model/src/workspace.rs
+++ b/crates/project_model/src/workspace.rs
@@ -12,7 +12,7 @@ use proc_macro_api::ProcMacroClient;
 use rustc_hash::{FxHashMap, FxHashSet};
 
 use crate::{
-    build_data::{BuildData, BuildDataMap, BuildDataResult},
+    build_data::{BuildDataResult, PackageBuildData, WorkspaceBuildData},
     cargo_workspace,
     cfg_flag::CfgFlag,
     rustc_cfg,
@@ -354,10 +354,10 @@ fn cargo_to_crate_graph(
     proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
     load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
     cargo: &CargoWorkspace,
-    build_data_map: Option<&BuildDataMap>,
+    build_data_map: Option<&WorkspaceBuildData>,
     sysroot: &Sysroot,
     rustc: &Option<CargoWorkspace>,
-    rustc_build_data_map: Option<&BuildDataMap>,
+    rustc_build_data_map: Option<&WorkspaceBuildData>,
 ) -> CrateGraph {
     let _p = profile::span("cargo_to_crate_graph");
     let mut crate_graph = CrateGraph::default();
@@ -464,7 +464,7 @@ fn handle_rustc_crates(
     rustc_workspace: &CargoWorkspace,
     load: &mut dyn FnMut(&AbsPath) -> Option<FileId>,
     crate_graph: &mut CrateGraph,
-    rustc_build_data_map: Option<&FxHashMap<String, BuildData>>,
+    rustc_build_data_map: Option<&WorkspaceBuildData>,
     cfg_options: &CfgOptions,
     proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
     pkg_to_lib_crate: &mut FxHashMap<la_arena::Idx<crate::PackageData>, CrateId>,
@@ -555,7 +555,7 @@ fn handle_rustc_crates(
 fn add_target_crate_root(
     crate_graph: &mut CrateGraph,
     pkg: &cargo_workspace::PackageData,
-    build_data: Option<&BuildData>,
+    build_data: Option<&PackageBuildData>,
     cfg_options: &CfgOptions,
     proc_macro_loader: &dyn Fn(&Path) -> Vec<ProcMacro>,
     file_id: FileId,
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index 18fd7ea74..fe9f273b0 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -12,7 +12,7 @@ use hir::{
     AssocItem, Crate, Function, HasSource, HirDisplay, ModuleDef,
 };
 use hir_def::FunctionId;
-use hir_ty::TypeWalk;
+use hir_ty::{TyExt, TypeWalk};
 use ide::{AnalysisHost, RootDatabase};
 use ide_db::base_db::{
     salsa::{self, ParallelDatabase},
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index cda272fd4..e012b4452 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -445,8 +445,8 @@ impl Config {
     pub fn hover_actions(&self) -> bool {
         self.experimental("hoverActions")
     }
-    pub fn status_notification(&self) -> bool {
-        self.experimental("statusNotification")
+    pub fn server_status_notification(&self) -> bool {
+        self.experimental("serverStatusNotification")
     }
 
     pub fn publish_diagnostics(&self) -> bool {
diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index 8679c8599..adeb7a97e 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -23,6 +23,7 @@ use crate::{
     document::DocumentData,
     from_proto,
     line_index::{LineEndings, LineIndex},
+    lsp_ext,
     main_loop::Task,
     op_queue::OpQueue,
     reload::SourceRootConfig,
@@ -32,20 +33,6 @@ use crate::{
     Result,
 };
 
-#[derive(Eq, PartialEq, Copy, Clone)]
-pub(crate) enum Status {
-    Loading,
-    Ready { partial: bool },
-    Invalid,
-    NeedsReload,
-}
-
-impl Default for Status {
-    fn default() -> Self {
-        Status::Loading
-    }
-}
-
 // Enforces drop order
 pub(crate) struct Handle<H, C> {
     pub(crate) handle: H,
@@ -67,26 +54,36 @@ pub(crate) struct GlobalState {
     req_queue: ReqQueue,
     pub(crate) task_pool: Handle<TaskPool<Task>, Receiver<Task>>,
     pub(crate) loader: Handle<Box<dyn vfs::loader::Handle>, Receiver<vfs::loader::Message>>,
-    pub(crate) vfs_config_version: u32,
-    pub(crate) flycheck: Vec<FlycheckHandle>,
-    pub(crate) flycheck_sender: Sender<flycheck::Message>,
-    pub(crate) flycheck_receiver: Receiver<flycheck::Message>,
     pub(crate) config: Arc<Config>,
     pub(crate) analysis_host: AnalysisHost,
     pub(crate) diagnostics: DiagnosticCollection,
     pub(crate) mem_docs: FxHashMap<VfsPath, DocumentData>,
     pub(crate) semantic_tokens_cache: Arc<Mutex<FxHashMap<Url, SemanticTokens>>>,
-    pub(crate) vfs: Arc<RwLock<(vfs::Vfs, FxHashMap<FileId, LineEndings>)>>,
     pub(crate) shutdown_requested: bool,
-    pub(crate) status: Status,
+    pub(crate) last_reported_status: Option<lsp_ext::ServerStatusParams>,
     pub(crate) source_root_config: SourceRootConfig,
     pub(crate) proc_macro_client: Option<ProcMacroClient>,
 
-    pub(crate) workspaces: Arc<Vec<ProjectWorkspace>>,
-    pub(crate) fetch_workspaces_queue: OpQueue<(), ()>,
+    pub(crate) flycheck: Vec<FlycheckHandle>,
+    pub(crate) flycheck_sender: Sender<flycheck::Message>,
+    pub(crate) flycheck_receiver: Receiver<flycheck::Message>,
 
+    pub(crate) vfs: Arc<RwLock<(vfs::Vfs, FxHashMap<FileId, LineEndings>)>>,
+    pub(crate) vfs_config_version: u32,
+    pub(crate) vfs_progress_config_version: u32,
+    pub(crate) vfs_progress_n_total: usize,
+    pub(crate) vfs_progress_n_done: usize,
+
+    /// For both `workspaces` and `workspace_build_data`, the field stores the
+    /// data we actually use, while the `OpQueue` stores the result of the last
+    /// fetch.
+    ///
+    /// If the fetch (partially) fails, we do not update the values.
+    pub(crate) workspaces: Arc<Vec<ProjectWorkspace>>,
+    pub(crate) fetch_workspaces_queue: OpQueue<(), Vec<anyhow::Result<ProjectWorkspace>>>,
     pub(crate) workspace_build_data: Option<BuildDataResult>,
-    pub(crate) fetch_build_data_queue: OpQueue<BuildDataCollector, ()>,
+    pub(crate) fetch_build_data_queue:
+        OpQueue<BuildDataCollector, Option<anyhow::Result<BuildDataResult>>>,
 
     latest_requests: Arc<RwLock<LatestRequests>>,
 }
@@ -124,25 +121,32 @@ impl GlobalState {
         GlobalState {
             sender,
             req_queue: ReqQueue::default(),
-            vfs_config_version: 0,
             task_pool,
             loader,
-            flycheck: Vec::new(),
-            flycheck_sender,
-            flycheck_receiver,
             config: Arc::new(config),
             analysis_host,
             diagnostics: Default::default(),
             mem_docs: FxHashMap::default(),
             semantic_tokens_cache: Arc::new(Default::default()),
-            vfs: Arc::new(RwLock::new((vfs::Vfs::default(), FxHashMap::default()))),
             shutdown_requested: false,
-            status: Status::default(),
+            last_reported_status: None,
             source_root_config: SourceRootConfig::default(),
             proc_macro_client: None,
+
+            flycheck: Vec::new(),
+            flycheck_sender,
+            flycheck_receiver,
+
+            vfs: Arc::new(RwLock::new((vfs::Vfs::default(), FxHashMap::default()))),
+            vfs_config_version: 0,
+            vfs_progress_config_version: 0,
+            vfs_progress_n_total: 0,
+            vfs_progress_n_done: 0,
+
             workspaces: Arc::new(Vec::new()),
             fetch_workspaces_queue: OpQueue::default(),
             workspace_build_data: None,
+
             fetch_build_data_queue: OpQueue::default(),
             latest_requests: Default::default(),
         }
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index 0e1fec209..81a6f22f1 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -241,26 +241,26 @@ pub struct SsrParams {
     pub selections: Vec<lsp_types::Range>,
 }
 
-pub enum StatusNotification {}
+pub enum ServerStatusNotification {}
 
-#[derive(Serialize, Deserialize)]
-#[serde(rename_all = "camelCase")]
-pub enum Status {
-    Loading,
-    ReadyPartial,
-    Ready,
-    NeedsReload,
-    Invalid,
+impl Notification for ServerStatusNotification {
+    type Params = ServerStatusParams;
+    const METHOD: &'static str = "experimental/serverStatus";
 }
 
-#[derive(Deserialize, Serialize)]
-pub struct StatusParams {
-    pub status: Status,
+#[derive(Deserialize, Serialize, PartialEq, Eq, Clone)]
+pub struct ServerStatusParams {
+    pub health: Health,
+    pub quiescent: bool,
+    pub message: Option<String>,
 }
 
-impl Notification for StatusNotification {
-    type Params = StatusParams;
-    const METHOD: &'static str = "rust-analyzer/status";
+#[derive(Serialize, Deserialize, Clone, Copy, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub enum Health {
+    Ok,
+    Warning,
+    Error,
 }
 
 pub enum CodeActionRequest {}
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index e88f16cc1..a5655116b 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -2,6 +2,7 @@
 //! requests/replies and notifications back to the client.
 use std::{
     env, fmt,
+    sync::Arc,
     time::{Duration, Instant},
 };
 
@@ -12,6 +13,7 @@ use ide::{Canceled, FileId};
 use ide_db::base_db::VfsPath;
 use lsp_server::{Connection, Notification, Request, Response};
 use lsp_types::notification::Notification as _;
+use project_model::BuildDataCollector;
 use vfs::ChangeKind;
 
 use crate::{
@@ -19,7 +21,7 @@ use crate::{
     dispatch::{NotificationDispatcher, RequestDispatcher},
     document::DocumentData,
     from_proto,
-    global_state::{file_id_to_url, url_to_file_id, GlobalState, Status},
+    global_state::{file_id_to_url, url_to_file_id, GlobalState},
     handlers, lsp_ext,
     lsp_utils::{apply_document_changes, is_canceled, notification_is, Progress},
     reload::{BuildDataProgress, ProjectWorkspaceProgress},
@@ -187,7 +189,7 @@ impl GlobalState {
             log::info!("task queue len: {}", task_queue_len);
         }
 
-        let mut new_status = self.status;
+        let was_quiescent = self.is_quiescent();
         match event {
             Event::Lsp(msg) => match msg {
                 lsp_server::Message::Request(req) => self.on_request(loop_start, req)?,
@@ -227,11 +229,24 @@ impl GlobalState {
                                     (Progress::Report, Some(msg))
                                 }
                                 ProjectWorkspaceProgress::End(workspaces) => {
-                                    self.fetch_workspaces_completed();
-                                    self.switch_workspaces(workspaces, None);
+                                    self.fetch_workspaces_completed(workspaces);
+
+                                    let old = Arc::clone(&self.workspaces);
+                                    self.switch_workspaces();
+                                    let workspaces_updated = !Arc::ptr_eq(&old, &self.workspaces);
+
+                                    if self.config.run_build_scripts() && workspaces_updated {
+                                        let mut collector = BuildDataCollector::default();
+                                        for ws in self.workspaces.iter() {
+                                            ws.collect_build_data_configs(&mut collector);
+                                        }
+                                        self.fetch_build_data_request(collector)
+                                    }
+
                                     (Progress::End, None)
                                 }
                             };
+
                             self.report_progress("fetching", state, msg, None);
                         }
                         Task::FetchBuildData(progress) => {
@@ -240,19 +255,21 @@ impl GlobalState {
                                 BuildDataProgress::Report(msg) => {
                                     (Some(Progress::Report), Some(msg))
                                 }
-                                BuildDataProgress::End(collector) => {
-                                    self.fetch_build_data_completed();
-                                    let workspaces =
-                                        (*self.workspaces).clone().into_iter().map(Ok).collect();
-                                    self.switch_workspaces(workspaces, Some(collector));
+                                BuildDataProgress::End(build_data_result) => {
+                                    self.fetch_build_data_completed(build_data_result);
+
+                                    self.switch_workspaces();
+
                                     (Some(Progress::End), None)
                                 }
                             };
+
                             if let Some(state) = state {
                                 self.report_progress("loading", state, msg, None);
                             }
                         }
                     }
+
                     // Coalesce multiple task events into one loop turn
                     task = match self.task_pool.receiver.try_recv() {
                         Ok(task) => task,
@@ -298,30 +315,25 @@ impl GlobalState {
                         }
                         vfs::loader::Message::Progress { n_total, n_done, config_version } => {
                             always!(config_version <= self.vfs_config_version);
-                            if n_total == 0 {
-                                new_status = Status::Invalid;
+
+                            self.vfs_progress_config_version = config_version;
+                            self.vfs_progress_n_total = n_total;
+                            self.vfs_progress_n_done = n_done;
+
+                            let state = if n_done == 0 {
+                                Progress::Begin
+                            } else if n_done < n_total {
+                                Progress::Report
                             } else {
-                                let state = if n_done == 0 {
-                                    new_status = Status::Loading;
-                                    Progress::Begin
-                                } else if n_done < n_total {
-                                    Progress::Report
-                                } else {
-                                    assert_eq!(n_done, n_total);
-                                    new_status = Status::Ready {
-                                        partial: self.config.run_build_scripts()
-                                            && self.workspace_build_data.is_none()
-                                            || config_version < self.vfs_config_version,
-                                    };
-                                    Progress::End
-                                };
-                                self.report_progress(
-                                    "roots scanned",
-                                    state,
-                                    Some(format!("{}/{}", n_done, n_total)),
-                                    Some(Progress::fraction(n_done, n_total)),
-                                )
-                            }
+                                assert_eq!(n_done, n_total);
+                                Progress::End
+                            };
+                            self.report_progress(
+                                "roots scanned",
+                                state,
+                                Some(format!("{}/{}", n_done, n_total)),
+                                Some(Progress::fraction(n_done, n_total)),
+                            )
                         }
                     }
                     // Coalesce many VFS event into a single loop turn
@@ -397,18 +409,14 @@ impl GlobalState {
         }
 
         let state_changed = self.process_changes();
-        let prev_status = self.status;
-        if prev_status != new_status {
-            self.transition(new_status);
-        }
-        let is_ready = matches!(self.status, Status::Ready { .. });
-        if prev_status == Status::Loading && is_ready {
+
+        if self.is_quiescent() && !was_quiescent {
             for flycheck in &self.flycheck {
                 flycheck.update();
             }
         }
 
-        if is_ready && (state_changed || prev_status == Status::Loading) {
+        if self.is_quiescent() && (!was_quiescent || state_changed) {
             self.update_file_notifications_on_threadpool();
 
             // Refresh semantic tokens if the client supports it.
@@ -437,9 +445,13 @@ impl GlobalState {
             }
         }
 
-        self.fetch_workspaces_if_needed();
+        if self.config.cargo_autoreload() {
+            self.fetch_workspaces_if_needed();
+        }
         self.fetch_build_data_if_needed();
 
+        self.report_new_status_if_needed();
+
         let loop_duration = loop_start.elapsed();
         if loop_duration > Duration::from_millis(100) {
             log::warn!("overly long loop turn: {:?}", loop_duration);
@@ -466,7 +478,8 @@ impl GlobalState {
             return Ok(());
         }
 
-        if self.status == Status::Loading && req.method != "shutdown" {
+        // Avoid flashing a bunch of unresolved references during initial load.
+        if self.workspaces.is_empty() && !self.is_quiescent() {
             self.respond(lsp_server::Response::new_err(
                 req.id,
                 // FIXME: i32 should impl From<ErrorCode> (from() guarantees lossless conversion)
@@ -477,7 +490,11 @@ impl GlobalState {
         }
 
         RequestDispatcher { req: Some(req), global_state: self }
-            .on_sync::<lsp_ext::ReloadWorkspace>(|s, ()| Ok(s.fetch_workspaces_request()))?
+            .on_sync::<lsp_ext::ReloadWorkspace>(|s, ()| {
+                s.fetch_workspaces_request();
+                s.fetch_workspaces_if_needed();
+                Ok(())
+            })?
             .on_sync::<lsp_ext::JoinLines>(|s, p| handlers::handle_join_lines(s.snapshot(), p))?
             .on_sync::<lsp_ext::OnEnter>(|s, p| handlers::handle_on_enter(s.snapshot(), p))?
             .on_sync::<lsp_types::request::Shutdown>(|s, ()| {
diff --git a/crates/rust-analyzer/src/op_queue.rs b/crates/rust-analyzer/src/op_queue.rs
index f71b718bc..1d612a933 100644
--- a/crates/rust-analyzer/src/op_queue.rs
+++ b/crates/rust-analyzer/src/op_queue.rs
@@ -2,27 +2,27 @@
 //! at a time.
 
 pub(crate) struct OpQueue<Args, Output> {
-    op_scheduled: Option<Args>,
+    op_requested: Option<Args>,
     op_in_progress: bool,
     last_op_result: Output,
 }
 
 impl<Args, Output: Default> Default for OpQueue<Args, Output> {
     fn default() -> Self {
-        Self { op_scheduled: None, op_in_progress: false, last_op_result: Default::default() }
+        Self { op_requested: None, op_in_progress: false, last_op_result: Default::default() }
     }
 }
 
 impl<Args, Output> OpQueue<Args, Output> {
     pub(crate) fn request_op(&mut self, data: Args) {
-        self.op_scheduled = Some(data);
+        self.op_requested = Some(data);
     }
     pub(crate) fn should_start_op(&mut self) -> Option<Args> {
         if self.op_in_progress {
             return None;
         }
-        self.op_in_progress = self.op_scheduled.is_some();
-        self.op_scheduled.take()
+        self.op_in_progress = self.op_requested.is_some();
+        self.op_requested.take()
     }
     pub(crate) fn op_completed(&mut self, result: Output) {
         assert!(self.op_in_progress);
@@ -34,4 +34,10 @@ impl<Args, Output> OpQueue<Args, Output> {
     pub(crate) fn last_op_result(&self) -> &Output {
         &self.last_op_result
     }
+    pub(crate) fn op_in_progress(&self) -> bool {
+        self.op_in_progress
+    }
+    pub(crate) fn op_requested(&self) -> bool {
+        self.op_requested.is_some()
+    }
 }
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index d12f891bb..d0cc1b61a 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -9,11 +9,10 @@ use vfs::{file_set::FileSetConfig, AbsPath, AbsPathBuf, ChangeKind};
 
 use crate::{
     config::{Config, FilesWatcher, LinkedProject},
-    global_state::{GlobalState, Status},
+    global_state::GlobalState,
     lsp_ext,
     main_loop::Task,
 };
-use lsp_ext::StatusParams;
 
 #[derive(Debug)]
 pub(crate) enum ProjectWorkspaceProgress {
@@ -30,6 +29,13 @@ pub(crate) enum BuildDataProgress {
 }
 
 impl GlobalState {
+    pub(crate) fn is_quiescent(&self) -> bool {
+        !(self.fetch_workspaces_queue.op_in_progress()
+            || self.fetch_build_data_queue.op_in_progress()
+            || self.vfs_progress_config_version < self.vfs_config_version
+            || self.vfs_progress_n_done < self.vfs_progress_n_total)
+    }
+
     pub(crate) fn update_configuration(&mut self, config: Config) {
         let _p = profile::span("GlobalState::update_configuration");
         let old_config = mem::replace(&mut self.config, Arc::new(config));
@@ -46,25 +52,17 @@ impl GlobalState {
         if !changes.iter().any(|(path, kind)| is_interesting(path, *kind)) {
             return;
         }
-        match self.status {
-            Status::Loading | Status::NeedsReload => return,
-            Status::Ready { .. } | Status::Invalid => (),
-        }
         log::info!(
-            "Reloading workspace because of the following changes: {}",
+            "Requesting workspace reload because of the following changes: {}",
             itertools::join(
                 changes
                     .iter()
                     .filter(|(path, kind)| is_interesting(path, *kind))
-                    .map(|(path, kind)| format!("{}/{:?}", path.display(), kind)),
+                    .map(|(path, kind)| format!("{}: {:?}", path.display(), kind)),
                 ", "
             )
         );
-        if self.config.cargo_autoreload() {
-            self.fetch_workspaces_request();
-        } else {
-            self.transition(Status::NeedsReload);
-        }
+        self.fetch_workspaces_request();
 
         fn is_interesting(path: &AbsPath, change_kind: ChangeKind) -> bool {
             const IMPLICIT_TARGET_FILES: &[&str] = &["build.rs", "src/main.rs", "src/lib.rs"];
@@ -101,46 +99,38 @@ impl GlobalState {
             false
         }
     }
-    pub(crate) fn transition(&mut self, new_status: Status) {
-        self.status = new_status;
-        if self.config.status_notification() {
-            let lsp_status = match new_status {
-                Status::Loading => lsp_ext::Status::Loading,
-                Status::Ready { partial: true } => lsp_ext::Status::ReadyPartial,
-                Status::Ready { partial: false } => lsp_ext::Status::Ready,
-                Status::Invalid => lsp_ext::Status::Invalid,
-                Status::NeedsReload => lsp_ext::Status::NeedsReload,
-            };
-            self.send_notification::<lsp_ext::StatusNotification>(StatusParams {
-                status: lsp_status,
-            });
+    pub(crate) fn report_new_status_if_needed(&mut self) {
+        if !self.config.server_status_notification() {
+            return;
         }
-    }
-
-    pub(crate) fn fetch_build_data_request(&mut self, build_data_collector: BuildDataCollector) {
-        self.fetch_build_data_queue.request_op(build_data_collector);
-    }
 
-    pub(crate) fn fetch_build_data_if_needed(&mut self) {
-        let mut build_data_collector = match self.fetch_build_data_queue.should_start_op() {
-            Some(it) => it,
-            None => return,
+        let mut status = lsp_ext::ServerStatusParams {
+            health: lsp_ext::Health::Ok,
+            quiescent: self.is_quiescent(),
+            message: None,
         };
-        self.task_pool.handle.spawn_with_sender(move |sender| {
-            sender.send(Task::FetchBuildData(BuildDataProgress::Begin)).unwrap();
 
-            let progress = {
-                let sender = sender.clone();
-                move |msg| {
-                    sender.send(Task::FetchBuildData(BuildDataProgress::Report(msg))).unwrap()
-                }
-            };
-            let res = build_data_collector.collect(&progress);
-            sender.send(Task::FetchBuildData(BuildDataProgress::End(res))).unwrap();
-        });
-    }
-    pub(crate) fn fetch_build_data_completed(&mut self) {
-        self.fetch_build_data_queue.op_completed(())
+        if let Some(error) = self.build_data_error() {
+            status.health = lsp_ext::Health::Warning;
+            status.message = Some(error)
+        }
+        if !self.config.cargo_autoreload()
+            && self.is_quiescent()
+            && self.fetch_workspaces_queue.op_requested()
+        {
+            status.health = lsp_ext::Health::Warning;
+            status.message = Some("Workspace reload required".to_string())
+        }
+
+        if let Some(error) = self.fetch_workspace_error() {
+            status.health = lsp_ext::Health::Error;
+            status.message = Some(error)
+        }
+
+        if self.last_reported_status.as_ref() != Some(&status) {
+            self.last_reported_status = Some(status.clone());
+            self.send_notification::<lsp_ext::ServerStatusNotification>(status);
+        }
     }
 
     pub(crate) fn fetch_workspaces_request(&mut self) {
@@ -194,54 +184,71 @@ impl GlobalState {
             }
         });
     }
-    pub(crate) fn fetch_workspaces_completed(&mut self) {
-        self.fetch_workspaces_queue.op_completed(())
+    pub(crate) fn fetch_workspaces_completed(
+        &mut self,
+        workspaces: Vec<anyhow::Result<ProjectWorkspace>>,
+    ) {
+        self.fetch_workspaces_queue.op_completed(workspaces)
+    }
+
+    pub(crate) fn fetch_build_data_request(&mut self, build_data_collector: BuildDataCollector) {
+        self.fetch_build_data_queue.request_op(build_data_collector);
     }
+    pub(crate) fn fetch_build_data_if_needed(&mut self) {
+        let mut build_data_collector = match self.fetch_build_data_queue.should_start_op() {
+            Some(it) => it,
+            None => return,
+        };
+        self.task_pool.handle.spawn_with_sender(move |sender| {
+            sender.send(Task::FetchBuildData(BuildDataProgress::Begin)).unwrap();
 
-    pub(crate) fn switch_workspaces(
+            let progress = {
+                let sender = sender.clone();
+                move |msg| {
+                    sender.send(Task::FetchBuildData(BuildDataProgress::Report(msg))).unwrap()
+                }
+            };
+            let res = build_data_collector.collect(&progress);
+            sender.send(Task::FetchBuildData(BuildDataProgress::End(res))).unwrap();
+        });
+    }
+    pub(crate) fn fetch_build_data_completed(
         &mut self,
-        workspaces: Vec<anyhow::Result<ProjectWorkspace>>,
-        workspace_build_data: Option<anyhow::Result<BuildDataResult>>,
+        build_data: anyhow::Result<BuildDataResult>,
     ) {
-        let _p = profile::span("GlobalState::switch_workspaces");
-        log::info!("will switch workspaces: {:?}", workspaces);
+        self.fetch_build_data_queue.op_completed(Some(build_data))
+    }
 
-        let mut has_errors = false;
-        let workspaces = workspaces
-            .into_iter()
-            .filter_map(|res| {
-                res.map_err(|err| {
-                    has_errors = true;
-                    log::error!("failed to load workspace: {:#}", err);
-                    if self.workspaces.is_empty() {
-                        self.show_message(
-                            lsp_types::MessageType::Error,
-                            format!("rust-analyzer failed to load workspace: {:#}", err),
-                        );
-                    }
-                })
-                .ok()
-            })
-            .collect::<Vec<_>>();
+    pub(crate) fn switch_workspaces(&mut self) {
+        let _p = profile::span("GlobalState::switch_workspaces");
+        log::info!("will switch workspaces");
 
-        let workspace_build_data = match workspace_build_data {
-            Some(Ok(it)) => Some(it),
-            Some(Err(err)) => {
-                log::error!("failed to fetch build data: {:#}", err);
-                self.show_message(
-                    lsp_types::MessageType::Error,
-                    format!("rust-analyzer failed to fetch build data: {:#}", err),
-                );
+        if let Some(error_message) = self.fetch_workspace_error() {
+            log::error!("failed to switch workspaces: {}", error_message);
+            self.show_message(lsp_types::MessageType::Error, error_message);
+            if !self.workspaces.is_empty() {
                 return;
             }
-            None => None,
-        };
+        }
 
-        if *self.workspaces == workspaces && self.workspace_build_data == workspace_build_data {
-            return;
+        if let Some(error_message) = self.build_data_error() {
+            log::error!("failed to switch build data: {}", error_message);
+            self.show_message(lsp_types::MessageType::Error, error_message);
         }
 
-        if !self.workspaces.is_empty() && has_errors {
+        let workspaces = self
+            .fetch_workspaces_queue
+            .last_op_result()
+            .iter()
+            .filter_map(|res| res.as_ref().ok().cloned())
+            .collect::<Vec<_>>();
+
+        let workspace_build_data = match self.fetch_build_data_queue.last_op_result() {
+            Some(Ok(it)) => Some(it.clone()),
+            None | Some(Err(_)) => None,
+        };
+
+        if *self.workspaces == workspaces && self.workspace_build_data == workspace_build_data {
             return;
         }
 
@@ -337,14 +344,6 @@ impl GlobalState {
         };
         change.set_crate_graph(crate_graph);
 
-        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);
-            }
-            self.fetch_build_data_request(collector)
-        }
-
         self.source_root_config = project_folders.source_root_config;
         self.workspaces = Arc::new(workspaces);
         self.workspace_build_data = workspace_build_data;
@@ -355,6 +354,32 @@ impl GlobalState {
         log::info!("did switch workspaces");
     }
 
+    fn fetch_workspace_error(&self) -> Option<String> {
+        let mut buf = String::new();
+
+        for ws in self.fetch_workspaces_queue.last_op_result() {
+            if let Err(err) = ws {
+                stdx::format_to!(buf, "rust-analyzer failed to load workspace: {:#}\n", err);
+            }
+        }
+
+        if buf.is_empty() {
+            return None;
+        }
+
+        Some(buf)
+    }
+
+    fn build_data_error(&self) -> Option<String> {
+        match self.fetch_build_data_queue.last_op_result() {
+            Some(Err(err)) => {
+                Some(format!("rust-analyzer failed to fetch build data: {:#}\n", err))
+            }
+            Some(Ok(data)) => data.error(),
+            None => None,
+        }
+    }
+
     fn reload_flycheck(&mut self) {
         let _p = profile::span("GlobalState::reload_flycheck");
         let config = match self.config.flycheck() {
diff --git a/crates/rust-analyzer/tests/rust-analyzer/support.rs b/crates/rust-analyzer/tests/rust-analyzer/support.rs
index 95bf26f01..8d68f1b7d 100644
--- a/crates/rust-analyzer/tests/rust-analyzer/support.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/support.rs
@@ -103,7 +103,7 @@ impl<'a> Project<'a> {
                     ..Default::default()
                 }),
                 experimental: Some(json!({
-                    "statusNotification": true,
+                    "serverStatusNotification": true,
                 })),
                 ..Default::default()
             },
@@ -213,13 +213,12 @@ impl Server {
     }
     pub(crate) fn wait_until_workspace_is_loaded(self) -> Server {
         self.wait_for_message_cond(1, &|msg: &Message| match msg {
-            Message::Notification(n) if n.method == "rust-analyzer/status" => {
+            Message::Notification(n) if n.method == "experimental/serverStatus" => {
                 let status = n
                     .clone()
-                    .extract::<lsp_ext::StatusParams>("rust-analyzer/status")
-                    .unwrap()
-                    .status;
-                matches!(status, lsp_ext::Status::Ready)
+                    .extract::<lsp_ext::ServerStatusParams>("experimental/serverStatus")
+                    .unwrap();
+                status.quiescent
             }
             _ => false,
         })
diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index d26be4853..b0a18d58d 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -178,6 +178,7 @@ where
     start..start + len
 }
 
+#[repr(transparent)]
 pub struct JodChild(pub process::Child);
 
 impl ops::Deref for JodChild {
@@ -200,6 +201,13 @@ impl Drop for JodChild {
     }
 }
 
+impl JodChild {
+    pub fn into_inner(self) -> process::Child {
+        // SAFETY: repr transparent
+        unsafe { std::mem::transmute::<JodChild, process::Child>(self) }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/crates/vfs/Cargo.toml b/crates/vfs/Cargo.toml
index c318a68f7..894944b18 100644
--- a/crates/vfs/Cargo.toml
+++ b/crates/vfs/Cargo.toml
@@ -14,3 +14,4 @@ rustc-hash = "1.0"
 fst = "0.4"
 
 paths = { path = "../paths", version = "0.0.0" }
+indexmap = "1.6.2"
diff --git a/crates/vfs/src/path_interner.rs b/crates/vfs/src/path_interner.rs
index 2189e5e25..6e049f0d4 100644
--- a/crates/vfs/src/path_interner.rs
+++ b/crates/vfs/src/path_interner.rs
@@ -1,15 +1,22 @@
 //! Maps paths to compact integer ids. We don't care about clearings paths which
 //! no longer exist -- the assumption is total size of paths we ever look at is
 //! not too big.
-use rustc_hash::FxHashMap;
+use std::hash::BuildHasherDefault;
+
+use indexmap::IndexSet;
+use rustc_hash::FxHasher;
 
 use crate::{FileId, VfsPath};
 
 /// Structure to map between [`VfsPath`] and [`FileId`].
-#[derive(Default)]
 pub(crate) struct PathInterner {
-    map: FxHashMap<VfsPath, FileId>,
-    vec: Vec<VfsPath>,
+    map: IndexSet<VfsPath, BuildHasherDefault<FxHasher>>,
+}
+
+impl Default for PathInterner {
+    fn default() -> Self {
+        Self { map: IndexSet::default() }
+    }
 }
 
 impl PathInterner {
@@ -17,7 +24,7 @@ impl PathInterner {
     ///
     /// If `path` does not exists in `self`, returns [`None`].
     pub(crate) fn get(&self, path: &VfsPath) -> Option<FileId> {
-        self.map.get(path).copied()
+        self.map.get_index_of(path).map(|i| FileId(i as u32))
     }
 
     /// Insert `path` in `self`.
@@ -25,13 +32,9 @@ impl PathInterner {
     /// - If `path` already exists in `self`, returns its associated id;
     /// - Else, returns a newly allocated id.
     pub(crate) fn intern(&mut self, path: VfsPath) -> FileId {
-        if let Some(id) = self.get(&path) {
-            return id;
-        }
-        let id = FileId(self.vec.len() as u32);
-        self.map.insert(path.clone(), id);
-        self.vec.push(path);
-        id
+        let (id, _added) = self.map.insert_full(path);
+        assert!(id < u32::MAX as usize);
+        FileId(id as u32)
     }
 
     /// Returns the path corresponding to `id`.
@@ -40,6 +43,6 @@ impl PathInterner {
     ///
     /// Panics if `id` does not exists in `self`.
     pub(crate) fn lookup(&self, id: FileId) -> &VfsPath {
-        &self.vec[id.0 as usize]
+        self.map.get_index(id.0 as usize).unwrap()
     }
 }
diff --git a/docs/dev/lsp-extensions.md b/docs/dev/lsp-extensions.md
index 73be59a82..989771ac6 100644
--- a/docs/dev/lsp-extensions.md
+++ b/docs/dev/lsp-extensions.md
@@ -1,5 +1,5 @@
 <!---
-lsp_ext.rs hash: e8a7502bd2b2c2f5
+lsp_ext.rs hash: faae991334a151d0
 
 If you need to change the above hash to make the test pass, please check if you
 need to adjust this doc as well and ping this  issue:
@@ -419,23 +419,37 @@ Returns internal status message, mostly for debugging purposes.
 
 Reloads project information (that is, re-executes `cargo metadata`).
 
-## Status Notification
+## Server Status
 
-**Experimental Client Capability:** `{ "statusNotification": boolean }`
+**Experimental Client Capability:** `{ "serverStatus": boolean }`
 
-**Method:** `rust-analyzer/status`
+**Method:** `experimental/serverStatus`
 
 **Notification:**
 
 ```typescript
-interface StatusParams {
-    status: "loading" | "readyPartial" | "ready" | "invalid" | "needsReload",
+interface ServerStatusParams {
+    /// `ok` means that the server is completely functional.
+    ///
+    /// `warning` means that the server is partially functional.
+    /// It can server requests, but some results might be wrong due to,
+    /// for example, some missing dependencies.
+    ///
+    /// `error` means that the server is not functional. For example,
+    /// there's a fatal build configuration problem.
+    health: "ok" | "warning" | "error",
+    /// Is there any pending background work which might change the status?
+    /// For example, are dependencies being downloaded?
+    quiescent: bool,
+    /// Explanatory message to show on hover.
+    message?: string,
 }
 ```
 
 This notification is sent from server to client.
-The client can use it to display persistent status to the user (in modline).
-For `needsReload` state, the client can provide a context-menu action to run `rust-analyzer/reloadWorkspace` request.
+The client can use it to display *persistent* status to the user (in modline).
+It is similar to the `showMessage`, but is intended for stares rather than point-in-time events.
+
 
 ## Syntax Tree
 
diff --git a/editors/code/src/client.ts b/editors/code/src/client.ts
index 0771ca3b6..116f41df6 100644
--- a/editors/code/src/client.ts
+++ b/editors/code/src/client.ts
@@ -159,7 +159,7 @@ class ExperimentalFeatures implements lc.StaticFeature {
         caps.snippetTextEdit = true;
         caps.codeActionGroup = true;
         caps.hoverActions = true;
-        caps.statusNotification = true;
+        caps.serverStatusNotification = true;
         capabilities.experimental = caps;
     }
     initialize(_capabilities: lc.ServerCapabilities<any>, _documentSelector: lc.DocumentSelector | undefined): void {
diff --git a/editors/code/src/ctx.ts b/editors/code/src/ctx.ts
index c07583cfa..bd023f803 100644
--- a/editors/code/src/ctx.ts
+++ b/editors/code/src/ctx.ts
@@ -5,7 +5,7 @@ import * as ra from './lsp_ext';
 import { Config } from './config';
 import { createClient } from './client';
 import { isRustEditor, RustEditor } from './util';
-import { Status } from './lsp_ext';
+import { ServerStatusParams } from './lsp_ext';
 
 export class Ctx {
     private constructor(
@@ -36,7 +36,7 @@ export class Ctx {
 
         res.pushCleanup(client.start());
         await client.onReady();
-        client.onNotification(ra.status, (params) => res.setStatus(params.status));
+        client.onNotification(ra.serverStatus, (params) => res.setServerStatus(params));
         return res;
     }
 
@@ -66,39 +66,28 @@ export class Ctx {
         return this.extCtx.subscriptions;
     }
 
-    setStatus(status: Status) {
-        switch (status) {
-            case "loading":
-                this.statusBar.text = "$(sync~spin) rust-analyzer";
-                this.statusBar.tooltip = "Loading the project";
-                this.statusBar.command = undefined;
+    setServerStatus(status: ServerStatusParams) {
+        this.statusBar.tooltip = status.message ?? "Ready";
+        let icon = "";
+        switch (status.health) {
+            case "ok":
                 this.statusBar.color = undefined;
                 break;
-            case "readyPartial":
-                this.statusBar.text = "rust-analyzer";
-                this.statusBar.tooltip = "Ready (Partial)";
-                this.statusBar.command = undefined;
-                this.statusBar.color = undefined;
-                break;
-            case "ready":
-                this.statusBar.text = "rust-analyzer";
-                this.statusBar.tooltip = "Ready";
-                this.statusBar.command = undefined;
-                this.statusBar.color = undefined;
-                break;
-            case "invalid":
-                this.statusBar.text = "$(error) rust-analyzer";
-                this.statusBar.tooltip = "Failed to load the project";
-                this.statusBar.command = undefined;
-                this.statusBar.color = new vscode.ThemeColor("notificationsErrorIcon.foreground");
-                break;
-            case "needsReload":
-                this.statusBar.text = "$(warning) rust-analyzer";
-                this.statusBar.tooltip = "Click to reload";
+            case "warning":
+                this.statusBar.tooltip += "\nClick to reload.";
                 this.statusBar.command = "rust-analyzer.reloadWorkspace";
                 this.statusBar.color = new vscode.ThemeColor("notificationsWarningIcon.foreground");
+                icon = "$(warning) ";
+                break;
+            case "error":
+                this.statusBar.tooltip += "\nClick to reload.";
+                this.statusBar.command = "rust-analyzer.reloadWorkspace";
+                this.statusBar.color = new vscode.ThemeColor("notificationsErrorIcon.foreground");
+                icon = "$(error) ";
                 break;
         }
+        if (!status.quiescent) icon = "$(sync~spin) ";
+        this.statusBar.text = `${icon} rust-analyzer`;
     }
 
     pushCleanup(d: Disposable) {
diff --git a/editors/code/src/lsp_ext.ts b/editors/code/src/lsp_ext.ts
index 00e128b8c..e453bb9e0 100644
--- a/editors/code/src/lsp_ext.ts
+++ b/editors/code/src/lsp_ext.ts
@@ -10,11 +10,12 @@ export interface AnalyzerStatusParams {
 export const analyzerStatus = new lc.RequestType<AnalyzerStatusParams, string, void>("rust-analyzer/analyzerStatus");
 export const memoryUsage = new lc.RequestType0<string, void>("rust-analyzer/memoryUsage");
 
-export type Status = "loading" | "ready" | "readyPartial" | "invalid" | "needsReload";
-export interface StatusParams {
-    status: Status;
+export interface ServerStatusParams {
+    health: "ok" | "warning" | "error";
+    quiescent: boolean;
+    message?: string;
 }
-export const status = new lc.NotificationType<StatusParams>("rust-analyzer/status");
+export const serverStatus = new lc.NotificationType<ServerStatusParams>("experimental/serverStatus");
 
 export const reloadWorkspace = new lc.RequestType0<null, void>("rust-analyzer/reloadWorkspace");