6 files changed, 149 insertions, 106 deletions

diff --git a/Cargo.lock b/Cargo.lock
index c06236692..007f05b4d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -114,7 +114,7 @@ checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 [[package]]
 name = "chalk-derive"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -125,7 +125,7 @@ dependencies = [
 [[package]]
 name = "chalk-engine"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "chalk-macros",
  "rustc-hash",
@@ -134,7 +134,7 @@ dependencies = [
 [[package]]
 name = "chalk-ir"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
@@ -144,7 +144,7 @@ dependencies = [
 [[package]]
 name = "chalk-macros"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "lazy_static",
 ]
@@ -152,7 +152,7 @@ dependencies = [
 [[package]]
 name = "chalk-rust-ir"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
@@ -163,14 +163,14 @@ dependencies = [
 [[package]]
 name = "chalk-solve"
 version = "0.10.1-dev"
-source = "git+https://github.com/rust-lang/chalk.git?rev=3e9c2503ae9c5277c2acb74624dc267876dd89b3#3e9c2503ae9c5277c2acb74624dc267876dd89b3"
+source = "git+https://github.com/rust-lang/chalk.git?rev=eaab84b394007d1bed15f5470409a6ea02900a96#eaab84b394007d1bed15f5470409a6ea02900a96"
 dependencies = [
  "chalk-derive",
  "chalk-engine",
  "chalk-ir",
  "chalk-macros",
  "chalk-rust-ir",
- "ena 0.13.1",
+ "ena",
  "itertools",
  "petgraph",
  "rustc-hash",
@@ -309,15 +309,6 @@ checksum = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 
 [[package]]
 name = "ena"
-version = "0.13.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8944dc8fa28ce4a38f778bd46bf7d923fe73eed5a439398507246c8e017e6f36"
-dependencies = [
- "log",
-]
-
-[[package]]
-name = "ena"
 version = "0.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7402b94a93c24e742487327a7cd839dc9d36fec9de9fb25b09f2dae459f36c3"
@@ -354,9 +345,9 @@ dependencies = [
 
 [[package]]
 name = "fixedbitset"
-version = "0.1.9"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86d4de0081402f5e88cdac65c8dcdcc73118c1a7a465e2a05f0da05843a8ea33"
+checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
 
 [[package]]
 name = "fnv"
@@ -658,9 +649,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-server"
-version = "0.3.1"
+version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5383e043329615624bbf45e1ba27bd75c176762b2592855c659bc28ac580a06b"
+checksum = "dccec31bfd027ac0dd288a78e19005fd89624d9099456e284b5241316a6c3072"
 dependencies = [
  "crossbeam-channel",
  "log",
@@ -814,12 +805,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b631f7e854af39a1739f401cf34a8a013dfe09eac4fa4dba91e9768bd28168d"
 
 [[package]]
-name = "ordermap"
-version = "0.3.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a86ed3f5f244b372d6b1a00b72ef7f8876d0bc6a78a4c9985c53614041512063"
-
-[[package]]
 name = "parking_lot"
 version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -873,12 +858,12 @@ checksum = "d4fd5641d01c8f18a23da7b6fe29298ff4b55afcccdf78973b24cf3175fee32e"
 
 [[package]]
 name = "petgraph"
-version = "0.4.13"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c3659d1ee90221741f65dd128d9998311b0e40c5d3c23a62445938214abce4f"
+checksum = "29c127eea4a29ec6c85d153c59dc1213f33ec74cead30fe4730aecc88cc1fd92"
 dependencies = [
  "fixedbitset",
- "ordermap",
+ "indexmap",
 ]
 
 [[package]]
@@ -1053,7 +1038,7 @@ dependencies = [
  "chalk-ir",
  "chalk-rust-ir",
  "chalk-solve",
- "ena 0.14.0",
+ "ena",
  "insta",
  "itertools",
  "log",
diff --git a/crates/ra_hir_ty/Cargo.toml b/crates/ra_hir_ty/Cargo.toml
index 5fc0ec5e3..b2de7fa34 100644
--- a/crates/ra_hir_ty/Cargo.toml
+++ b/crates/ra_hir_ty/Cargo.toml
@@ -27,9 +27,9 @@ test_utils = { path = "../test_utils" }
 
 scoped-tls = "1"
 
-chalk-solve =   { git = "https://github.com/rust-lang/chalk.git", rev = "3e9c2503ae9c5277c2acb74624dc267876dd89b3" }
-chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "3e9c2503ae9c5277c2acb74624dc267876dd89b3" }
-chalk-ir =      { git = "https://github.com/rust-lang/chalk.git", rev = "3e9c2503ae9c5277c2acb74624dc267876dd89b3" }
+chalk-solve =   { git = "https://github.com/rust-lang/chalk.git", rev = "eaab84b394007d1bed15f5470409a6ea02900a96" }
+chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "eaab84b394007d1bed15f5470409a6ea02900a96" }
+chalk-ir =      { git = "https://github.com/rust-lang/chalk.git", rev = "eaab84b394007d1bed15f5470409a6ea02900a96" }
 
 [dev-dependencies]
 insta = "0.16.0"
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index 5870618a0..c2d7abd17 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -4,7 +4,7 @@ use std::{fmt, sync::Arc};
 use log::debug;
 
 use chalk_ir::{
-    cast::Cast, fold::shift::Shift, interner::HasInterner, Goal, GoalData, Parameter,
+    cast::Cast, fold::shift::Shift, interner::HasInterner, GenericArg, Goal, GoalData,
     PlaceholderIndex, TypeName, UniverseIndex,
 };
 
@@ -26,24 +26,24 @@ pub(super) mod tls;
 pub struct Interner;
 
 impl chalk_ir::interner::Interner for Interner {
-    type InternedType = Box<chalk_ir::TyData<Self>>;
+    type InternedType = Box<chalk_ir::TyData<Self>>; // FIXME use Arc?
     type InternedLifetime = chalk_ir::LifetimeData<Self>;
-    type InternedParameter = chalk_ir::ParameterData<Self>;
+    type InternedConst = Arc<chalk_ir::ConstData<Self>>;
+    type InternedConcreteConst = ();
+    type InternedGenericArg = chalk_ir::GenericArgData<Self>;
     type InternedGoal = Arc<GoalData<Self>>;
     type InternedGoals = Vec<Goal<Self>>;
-    type InternedSubstitution = Vec<Parameter<Self>>;
+    type InternedSubstitution = Vec<GenericArg<Self>>;
     type InternedProgramClause = chalk_ir::ProgramClauseData<Self>;
     type InternedProgramClauses = Arc<[chalk_ir::ProgramClause<Self>]>;
     type InternedQuantifiedWhereClauses = Vec<chalk_ir::QuantifiedWhereClause<Self>>;
-    type InternedParameterKinds = Vec<chalk_ir::ParameterKind<()>>;
-    type InternedCanonicalVarKinds = Vec<chalk_ir::ParameterKind<UniverseIndex>>;
-    type Identifier = TypeAliasId;
+    type InternedVariableKinds = Vec<chalk_ir::VariableKind<Self>>;
+    type InternedCanonicalVarKinds = Vec<chalk_ir::CanonicalVarKind<Self>>;
     type DefId = InternId;
+    type InternedAdtId = InternId;
+    type Identifier = TypeAliasId;
 
-    fn debug_struct_id(
-        type_kind_id: StructId,
-        fmt: &mut fmt::Formatter<'_>,
-    ) -> Option<fmt::Result> {
+    fn debug_adt_id(type_kind_id: StructId, fmt: &mut fmt::Formatter<'_>) -> Option<fmt::Result> {
         tls::with_current_program(|prog| Some(prog?.debug_struct_id(type_kind_id, fmt)))
     }
 
@@ -94,11 +94,11 @@ impl chalk_ir::interner::Interner for Interner {
         tls::with_current_program(|prog| Some(prog?.debug_lifetime(lifetime, fmt)))
     }
 
-    fn debug_parameter(
-        parameter: &Parameter<Interner>,
+    fn debug_generic_arg(
+        parameter: &GenericArg<Interner>,
         fmt: &mut fmt::Formatter<'_>,
     ) -> Option<fmt::Result> {
-        tls::with_current_program(|prog| Some(prog?.debug_parameter(parameter, fmt)))
+        tls::with_current_program(|prog| Some(prog?.debug_generic_arg(parameter, fmt)))
     }
 
     fn debug_goal(goal: &Goal<Interner>, fmt: &mut fmt::Formatter<'_>) -> Option<fmt::Result> {
@@ -164,17 +164,32 @@ impl chalk_ir::interner::Interner for Interner {
         lifetime
     }
 
-    fn intern_parameter(
+    fn intern_const(&self, constant: chalk_ir::ConstData<Self>) -> Arc<chalk_ir::ConstData<Self>> {
+        Arc::new(constant)
+    }
+
+    fn const_data<'a>(
+        &self,
+        constant: &'a Arc<chalk_ir::ConstData<Self>>,
+    ) -> &'a chalk_ir::ConstData<Self> {
+        constant
+    }
+
+    fn const_eq(&self, _ty: &Box<chalk_ir::TyData<Self>>, _c1: &(), _c2: &()) -> bool {
+        true
+    }
+
+    fn intern_generic_arg(
         &self,
-        parameter: chalk_ir::ParameterData<Self>,
-    ) -> chalk_ir::ParameterData<Self> {
+        parameter: chalk_ir::GenericArgData<Self>,
+    ) -> chalk_ir::GenericArgData<Self> {
         parameter
     }
 
-    fn parameter_data<'a>(
+    fn generic_arg_data<'a>(
         &self,
-        parameter: &'a chalk_ir::ParameterData<Self>,
-    ) -> &'a chalk_ir::ParameterData<Self> {
+        parameter: &'a chalk_ir::GenericArgData<Self>,
+    ) -> &'a chalk_ir::GenericArgData<Self> {
         parameter
     }
 
@@ -199,15 +214,15 @@ impl chalk_ir::interner::Interner for Interner {
 
     fn intern_substitution<E>(
         &self,
-        data: impl IntoIterator<Item = Result<Parameter<Self>, E>>,
-    ) -> Result<Vec<Parameter<Self>>, E> {
+        data: impl IntoIterator<Item = Result<GenericArg<Self>, E>>,
+    ) -> Result<Vec<GenericArg<Self>>, E> {
         data.into_iter().collect()
     }
 
     fn substitution_data<'a>(
         &self,
-        substitution: &'a Vec<Parameter<Self>>,
-    ) -> &'a [Parameter<Self>] {
+        substitution: &'a Vec<GenericArg<Self>>,
+    ) -> &'a [GenericArg<Self>] {
         substitution
     }
 
@@ -253,23 +268,23 @@ impl chalk_ir::interner::Interner for Interner {
         clauses
     }
 
-    fn intern_parameter_kinds<E>(
+    fn intern_generic_arg_kinds<E>(
         &self,
-        data: impl IntoIterator<Item = Result<chalk_ir::ParameterKind<()>, E>>,
-    ) -> Result<Self::InternedParameterKinds, E> {
+        data: impl IntoIterator<Item = Result<chalk_ir::VariableKind<Self>, E>>,
+    ) -> Result<Self::InternedVariableKinds, E> {
         data.into_iter().collect()
     }
 
-    fn parameter_kinds_data<'a>(
+    fn variable_kinds_data<'a>(
         &self,
-        parameter_kinds: &'a Self::InternedParameterKinds,
-    ) -> &'a [chalk_ir::ParameterKind<()>] {
+        parameter_kinds: &'a Self::InternedVariableKinds,
+    ) -> &'a [chalk_ir::VariableKind<Self>] {
         &parameter_kinds
     }
 
     fn intern_canonical_var_kinds<E>(
         &self,
-        data: impl IntoIterator<Item = Result<chalk_ir::ParameterKind<UniverseIndex>, E>>,
+        data: impl IntoIterator<Item = Result<chalk_ir::CanonicalVarKind<Self>, E>>,
     ) -> Result<Self::InternedCanonicalVarKinds, E> {
         data.into_iter().collect()
     }
@@ -277,7 +292,7 @@ impl chalk_ir::interner::Interner for Interner {
     fn canonical_var_kinds_data<'a>(
         &self,
         canonical_var_kinds: &'a Self::InternedCanonicalVarKinds,
-    ) -> &'a [chalk_ir::ParameterKind<UniverseIndex>] {
+    ) -> &'a [chalk_ir::CanonicalVarKind<Self>] {
         &canonical_var_kinds
     }
 }
@@ -290,8 +305,8 @@ pub type AssocTypeId = chalk_ir::AssocTypeId<Interner>;
 pub type AssociatedTyDatum = chalk_rust_ir::AssociatedTyDatum<Interner>;
 pub type TraitId = chalk_ir::TraitId<Interner>;
 pub type TraitDatum = chalk_rust_ir::TraitDatum<Interner>;
-pub type StructId = chalk_ir::StructId<Interner>;
-pub type StructDatum = chalk_rust_ir::StructDatum<Interner>;
+pub type StructId = chalk_ir::AdtId<Interner>;
+pub type StructDatum = chalk_rust_ir::AdtDatum<Interner>;
 pub type ImplId = chalk_ir::ImplId<Interner>;
 pub type ImplDatum = chalk_rust_ir::ImplDatum<Interner>;
 pub type AssociatedTyValueId = chalk_rust_ir::AssociatedTyValueId<Interner>;
@@ -453,14 +468,14 @@ impl ToChalk for TypeCtor {
             _ => {
                 // other TypeCtors get interned and turned into a chalk StructId
                 let struct_id = db.intern_type_ctor(self).into();
-                TypeName::Struct(struct_id)
+                TypeName::Adt(struct_id)
             }
         }
     }
 
     fn from_chalk(db: &dyn HirDatabase, type_name: TypeName<Interner>) -> TypeCtor {
         match type_name {
-            TypeName::Struct(struct_id) => db.lookup_intern_type_ctor(struct_id.into()),
+            TypeName::Adt(struct_id) => db.lookup_intern_type_ctor(struct_id.into()),
             TypeName::AssociatedType(type_id) => TypeCtor::AssociatedType(from_chalk(db, type_id)),
             TypeName::OpaqueType(_) => unreachable!(),
 
@@ -471,6 +486,8 @@ impl ToChalk for TypeCtor {
             TypeName::Ref(_) => unreachable!(),
             TypeName::Str => unreachable!(),
 
+            TypeName::FnDef(_) => unreachable!(),
+
             TypeName::Error => {
                 // this should not be reached, since we don't represent TypeName::Error with TypeCtor
                 unreachable!()
@@ -622,7 +639,10 @@ where
     type Chalk = chalk_ir::Canonical<T::Chalk>;
 
     fn to_chalk(self, db: &dyn HirDatabase) -> chalk_ir::Canonical<T::Chalk> {
-        let parameter = chalk_ir::ParameterKind::Ty(chalk_ir::UniverseIndex::ROOT);
+        let parameter = chalk_ir::CanonicalVarKind::new(
+            chalk_ir::VariableKind::Ty,
+            chalk_ir::UniverseIndex::ROOT,
+        );
         let value = self.value.to_chalk(db);
         chalk_ir::Canonical {
             value,
@@ -738,9 +758,9 @@ where
     T: HasInterner<Interner = Interner>,
 {
     chalk_ir::Binders::new(
-        chalk_ir::ParameterKinds::from(
+        chalk_ir::VariableKinds::from(
             &Interner,
-            std::iter::repeat(chalk_ir::ParameterKind::Ty(())).take(num_vars),
+            std::iter::repeat(chalk_ir::VariableKind::Ty).take(num_vars),
         ),
         value,
     )
@@ -819,16 +839,25 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
     fn trait_datum(&self, trait_id: TraitId) -> Arc<TraitDatum> {
         self.db.trait_datum(self.krate, trait_id)
     }
-    fn struct_datum(&self, struct_id: StructId) -> Arc<StructDatum> {
+    fn adt_datum(&self, struct_id: StructId) -> Arc<StructDatum> {
         self.db.struct_datum(self.krate, struct_id)
     }
     fn impl_datum(&self, impl_id: ImplId) -> Arc<ImplDatum> {
         self.db.impl_datum(self.krate, impl_id)
     }
+
+    fn fn_def_datum(
+        &self,
+        _fn_def_id: chalk_ir::FnDefId<Interner>,
+    ) -> Arc<chalk_rust_ir::FnDefDatum<Interner>> {
+        // We don't yet provide any FnDefs to Chalk
+        unimplemented!()
+    }
+
     fn impls_for_trait(
         &self,
         trait_id: TraitId,
-        parameters: &[Parameter<Interner>],
+        parameters: &[GenericArg<Interner>],
     ) -> Vec<ImplId> {
         debug!("impls_for_trait {:?}", trait_id);
         let trait_: hir_def::TraitId = from_chalk(self.db, trait_id);
@@ -1000,7 +1029,7 @@ pub(crate) fn struct_datum_query(
     struct_id: StructId,
 ) -> Arc<StructDatum> {
     debug!("struct_datum {:?}", struct_id);
-    let type_ctor: TypeCtor = from_chalk(db, TypeName::Struct(struct_id));
+    let type_ctor: TypeCtor = from_chalk(db, TypeName::Adt(struct_id));
     debug!("struct {:?} = {:?}", struct_id, type_ctor);
     let num_params = type_ctor.num_ty_params(db);
     let upstream = type_ctor.krate(db) != Some(krate);
@@ -1012,12 +1041,12 @@ pub(crate) fn struct_datum_query(
             convert_where_clauses(db, generic_def, &bound_vars)
         })
         .unwrap_or_else(Vec::new);
-    let flags = chalk_rust_ir::StructFlags {
+    let flags = chalk_rust_ir::AdtFlags {
         upstream,
         // FIXME set fundamental flag correctly
         fundamental: false,
     };
-    let struct_datum_bound = chalk_rust_ir::StructDatumBound {
+    let struct_datum_bound = chalk_rust_ir::AdtDatumBound {
         fields: Vec::new(), // FIXME add fields (only relevant for auto traits)
         where_clauses,
     };
@@ -1153,7 +1182,7 @@ impl From<StructId> for crate::TypeCtorId {
 
 impl From<crate::TypeCtorId> for StructId {
     fn from(type_ctor_id: crate::TypeCtorId) -> Self {
-        chalk_ir::StructId(type_ctor_id.as_intern_id())
+        chalk_ir::AdtId(type_ctor_id.as_intern_id())
     }
 }
 
diff --git a/crates/ra_hir_ty/src/traits/chalk/tls.rs b/crates/ra_hir_ty/src/traits/chalk/tls.rs
index 4867cb17e..b7eb49d7b 100644
--- a/crates/ra_hir_ty/src/traits/chalk/tls.rs
+++ b/crates/ra_hir_ty/src/traits/chalk/tls.rs
@@ -1,7 +1,7 @@
 //! Implementation of Chalk debug helper functions using TLS.
 use std::fmt;
 
-use chalk_ir::{AliasTy, Goal, Goals, Lifetime, Parameter, ProgramClauseImplication, TypeName};
+use chalk_ir::{AliasTy, GenericArg, Goal, Goals, Lifetime, ProgramClauseImplication, TypeName};
 use itertools::Itertools;
 
 use super::{from_chalk, Interner};
@@ -18,7 +18,7 @@ impl DebugContext<'_> {
         id: super::StructId,
         f: &mut fmt::Formatter<'_>,
     ) -> Result<(), fmt::Error> {
-        let type_ctor: TypeCtor = from_chalk(self.0, TypeName::Struct(id));
+        let type_ctor: TypeCtor = from_chalk(self.0, TypeName::Adt(id));
         match type_ctor {
             TypeCtor::Bool => write!(f, "bool")?,
             TypeCtor::Char => write!(f, "char")?,
@@ -188,9 +188,9 @@ impl DebugContext<'_> {
         write!(fmt, "{:?}", lifetime.data(&Interner))
     }
 
-    pub fn debug_parameter(
+    pub fn debug_generic_arg(
         &self,
-        parameter: &Parameter<Interner>,
+        parameter: &GenericArg<Interner>,
         fmt: &mut fmt::Formatter<'_>,
     ) -> Result<(), fmt::Error> {
         write!(fmt, "{:?}", parameter.data(&Interner).inner_debug())
diff --git a/crates/rust-analyzer/src/bin/main.rs b/crates/rust-analyzer/src/bin/main.rs
index 09908458d..e82fd57de 100644
--- a/crates/rust-analyzer/src/bin/main.rs
+++ b/crates/rust-analyzer/src/bin/main.rs
@@ -74,12 +74,25 @@ fn run_server() -> Result<()> {
     log::info!("lifecycle: server started");
 
     let (connection, io_threads) = Connection::stdio();
-    let server_capabilities = serde_json::to_value(rust_analyzer::server_capabilities()).unwrap();
 
-    let initialize_params = connection.initialize(server_capabilities)?;
+    let (initialize_id, initialize_params) = connection.initialize_start()?;
     let initialize_params =
         from_json::<lsp_types::InitializeParams>("InitializeParams", initialize_params)?;
 
+    let server_capabilities = rust_analyzer::server_capabilities(&initialize_params.capabilities);
+
+    let initialize_result = lsp_types::InitializeResult {
+        capabilities: server_capabilities,
+        server_info: Some(lsp_types::ServerInfo {
+            name: String::from("rust-analyzer"),
+            version: Some(String::from(env!("REV"))),
+        }),
+    };
+
+    let initialize_result = serde_json::to_value(initialize_result).unwrap();
+
+    connection.initialize_finish(initialize_id, initialize_result)?;
+
     if let Some(client_info) = initialize_params.client_info {
         log::info!("Client '{}' {}", client_info.name, client_info.version.unwrap_or_default());
     }
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index 13af75469..780fc9317 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -2,19 +2,22 @@
 use std::env;
 
 use lsp_types::{
-    CallHierarchyServerCapability, CodeActionOptions, CodeActionProviderCapability,
-    CodeLensOptions, CompletionOptions, DocumentOnTypeFormattingOptions,
-    FoldingRangeProviderCapability, ImplementationProviderCapability, RenameOptions,
-    RenameProviderCapability, SaveOptions, SelectionRangeProviderCapability,
-    SemanticTokensDocumentProvider, SemanticTokensLegend, SemanticTokensOptions,
-    ServerCapabilities, SignatureHelpOptions, TextDocumentSyncCapability, TextDocumentSyncKind,
-    TextDocumentSyncOptions, TypeDefinitionProviderCapability, WorkDoneProgressOptions,
+    CallHierarchyServerCapability, ClientCapabilities, CodeActionOptions,
+    CodeActionProviderCapability, CodeLensOptions, CompletionOptions,
+    DocumentOnTypeFormattingOptions, FoldingRangeProviderCapability,
+    ImplementationProviderCapability, RenameOptions, RenameProviderCapability, SaveOptions,
+    SelectionRangeProviderCapability, SemanticTokensDocumentProvider, SemanticTokensLegend,
+    SemanticTokensOptions, ServerCapabilities, SignatureHelpOptions, TextDocumentSyncCapability,
+    TextDocumentSyncKind, TextDocumentSyncOptions, TypeDefinitionProviderCapability,
+    WorkDoneProgressOptions,
 };
 use serde_json::json;
 
 use crate::semantic_tokens;
 
-pub fn server_capabilities() -> ServerCapabilities {
+pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabilities {
+    let code_action_provider = code_action_capabilities(client_caps);
+
     ServerCapabilities {
         text_document_sync: Some(TextDocumentSyncCapability::Options(TextDocumentSyncOptions {
             open_close: Some(true),
@@ -46,20 +49,7 @@ pub fn server_capabilities() -> ServerCapabilities {
         document_highlight_provider: Some(true),
         document_symbol_provider: Some(true),
         workspace_symbol_provider: Some(true),
-        code_action_provider: Some(CodeActionProviderCapability::Options(CodeActionOptions {
-            // Advertise support for all built-in CodeActionKinds
-            code_action_kinds: Some(vec![
-                lsp_types::code_action_kind::EMPTY.to_string(),
-                lsp_types::code_action_kind::QUICKFIX.to_string(),
-                lsp_types::code_action_kind::REFACTOR.to_string(),
-                lsp_types::code_action_kind::REFACTOR_EXTRACT.to_string(),
-                lsp_types::code_action_kind::REFACTOR_INLINE.to_string(),
-                lsp_types::code_action_kind::REFACTOR_REWRITE.to_string(),
-                lsp_types::code_action_kind::SOURCE.to_string(),
-                lsp_types::code_action_kind::SOURCE_ORGANIZE_IMPORTS.to_string(),
-            ]),
-            work_done_progress_options: Default::default(),
-        })),
+        code_action_provider: Some(code_action_provider),
         code_lens_provider: Some(CodeLensOptions { resolve_provider: Some(true) }),
         document_formatting_provider: Some(true),
         document_range_formatting_provider: None,
@@ -98,3 +88,29 @@ pub fn server_capabilities() -> ServerCapabilities {
         })),
     }
 }
+
+fn code_action_capabilities(client_caps: &ClientCapabilities) -> CodeActionProviderCapability {
+    client_caps
+        .text_document
+        .as_ref()
+        .and_then(|it| it.code_action.as_ref())
+        .and_then(|it| it.code_action_literal_support.as_ref())
+        .map_or(CodeActionProviderCapability::Simple(true), |_| {
+            CodeActionProviderCapability::Options(CodeActionOptions {
+                // Advertise support for all built-in CodeActionKinds.
+                // Ideally we would base this off of the client capabilities
+                // but the client is supposed to fall back gracefully for unknown values.
+                code_action_kinds: Some(vec![
+                    lsp_types::code_action_kind::EMPTY.to_string(),
+                    lsp_types::code_action_kind::QUICKFIX.to_string(),
+                    lsp_types::code_action_kind::REFACTOR.to_string(),
+                    lsp_types::code_action_kind::REFACTOR_EXTRACT.to_string(),
+                    lsp_types::code_action_kind::REFACTOR_INLINE.to_string(),
+                    lsp_types::code_action_kind::REFACTOR_REWRITE.to_string(),
+                    lsp_types::code_action_kind::SOURCE.to_string(),
+                    lsp_types::code_action_kind::SOURCE_ORGANIZE_IMPORTS.to_string(),
+                ]),
+                work_done_progress_options: Default::default(),
+            })
+        })
+}