44 files changed, 1128 insertions, 710 deletions

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 5bc41533c..cb397ae14 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -14,6 +14,7 @@ jobs:
     env:
       RUSTFLAGS: -D warnings
       CARGO_INCREMENTAL: 0
+      RUN_SLOW_TESTS: 1
     steps:
 
       - name: Checkout repository
@@ -46,9 +47,10 @@ jobs:
 
       - name: Prepare build directory for cache
         run: |
-          find ./target/debug -maxdepth 1 -type f -delete && \
-          rm -fr ./target/debug/{deps,.fingerprint}/{*ra_*,*heavy_test*,*gen_lsp*,*thread_worker*} && \
-          rm -f  ./target/.rustc_info.json
+          find ./target/debug -maxdepth 1 -type f -delete \
+          && rm -fr ./target/debug/{deps,.fingerprint}/{*ra_*,*heavy_test*,*gen_lsp*,*thread_worker*} \
+          && rm -f  ./target/.rustc_info.json \
+          && rm ./target/.slow_tests_cookie
 
   type-script:
     name: TypeScript
diff --git a/Cargo.lock b/Cargo.lock
index 0e7594f80..a95f9139f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -14,6 +14,11 @@ version = "1.0.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "anymap"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "arrayvec"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -958,6 +963,7 @@ dependencies = [
 name = "ra_hir_def"
 version = "0.1.0"
 dependencies = [
+ "anymap 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1776,6 +1782,7 @@ dependencies = [
 [metadata]
 "checksum aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)" = "58fb5e95d83b38284460a5fda7d6470aa0b8844d283a0b614b8535e880800d2d"
 "checksum anyhow 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)" = "9267dff192e68f3399525901e709a48c1d3982c9c072fa32f2127a0cb0babf14"
+"checksum anymap 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)" = "33954243bd79057c2de7338850b85983a44588021f8a5fee574a8888c6de4344"
 "checksum arrayvec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cff77d8686867eceff3105329d4698d96c2391c176d5d03adc90c7389162b5b8"
 "checksum atty 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)" = "1803c647a3ec87095e7ae7acfca019e98de5ec9a7d01343f611cf3152ed71a90"
 "checksum autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "1d49d90015b3c36167a20fe2810c5cd875ad504b39cff3d4eae7977e6b7c1cb2"
diff --git a/crates/ra_assists/src/assists/add_new.rs b/crates/ra_assists/src/assists/add_new.rs
index f977547fb..d340cac8f 100644
--- a/crates/ra_assists/src/assists/add_new.rs
+++ b/crates/ra_assists/src/assists/add_new.rs
@@ -56,42 +56,39 @@ pub(crate) fn add_new(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
         let vis = vis.as_ref().map(String::as_str).unwrap_or("");
         write!(&mut buf, "    {}fn new(", vis).unwrap();
 
-        join(field_list.fields().map(|f| {
-            format!(
-                "{}: {}",
-                f.name().unwrap().syntax().text(),
-                f.ascribed_type().unwrap().syntax().text()
-            )
+        join(field_list.fields().filter_map(|f| {
+            Some(format!("{}: {}", f.name()?.syntax().text(), f.ascribed_type()?.syntax().text()))
         }))
         .separator(", ")
         .to_buf(&mut buf);
 
         buf.push_str(") -> Self { Self {");
 
-        join(field_list.fields().map(|f| f.name().unwrap().syntax().text()))
+        join(field_list.fields().filter_map(|f| Some(f.name()?.syntax().text())))
             .separator(", ")
             .surround_with(" ", " ")
             .to_buf(&mut buf);
 
         buf.push_str("} }");
 
-        let (start_offset, end_offset) = if let Some(impl_block) = impl_block {
-            buf.push('\n');
-            let start = impl_block
-                .syntax()
-                .descendants_with_tokens()
-                .find(|t| t.kind() == T!['{'])
-                .unwrap()
-                .text_range()
-                .end();
-
-            (start, TextUnit::from_usize(1))
-        } else {
-            buf = generate_impl_text(&strukt, &buf);
-            let start = strukt.syntax().text_range().end();
-
-            (start, TextUnit::from_usize(3))
-        };
+        let (start_offset, end_offset) = impl_block
+            .and_then(|impl_block| {
+                buf.push('\n');
+                let start = impl_block
+                    .syntax()
+                    .descendants_with_tokens()
+                    .find(|t| t.kind() == T!['{'])?
+                    .text_range()
+                    .end();
+
+                Some((start, TextUnit::from_usize(1)))
+            })
+            .unwrap_or_else(|| {
+                buf = generate_impl_text(&strukt, &buf);
+                let start = strukt.syntax().text_range().end();
+
+                (start, TextUnit::from_usize(3))
+            });
 
         edit.set_cursor(start_offset + TextUnit::of_str(&buf) - end_offset);
         edit.insert(start_offset, buf);
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 7706399ae..4578a0ba8 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -15,9 +15,9 @@ use hir_def::{
     per_ns::PerNs,
     resolver::HasResolver,
     type_ref::{Mutability, TypeRef},
-    AdtId, AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, FunctionId, GenericDefId,
-    HasModule, ImplId, LocalEnumVariantId, LocalImportId, LocalModuleId, LocalStructFieldId,
-    Lookup, ModuleId, StaticId, StructId, TraitId, TypeAliasId, UnionId,
+    AdtId, AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, FunctionId, HasModule, ImplId,
+    LocalEnumVariantId, LocalImportId, LocalModuleId, LocalStructFieldId, Lookup, ModuleId,
+    StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
 };
 use hir_expand::{
     diagnostics::DiagnosticSink,
@@ -856,9 +856,19 @@ impl Local {
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub struct GenericParam {
-    pub(crate) parent: GenericDefId,
-    pub(crate) idx: u32,
+pub struct TypeParam {
+    pub(crate) id: TypeParamId,
+}
+
+impl TypeParam {
+    pub fn name(self, db: &impl HirDatabase) -> Name {
+        let params = db.generic_params(self.id.parent);
+        params.types[self.id.local_id].name.clone()
+    }
+
+    pub fn module(self, db: &impl HirDatabase) -> Module {
+        self.id.parent.module(db).into()
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -1101,7 +1111,7 @@ impl HirDisplay for Type {
 pub enum ScopeDef {
     ModuleDef(ModuleDef),
     MacroDef(MacroDef),
-    GenericParam(GenericParam),
+    GenericParam(TypeParam),
     ImplSelfType(ImplBlock),
     AdtSelfType(Adt),
     Local(Local),
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index 78a454082..b09582f93 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -10,7 +10,7 @@ use ra_syntax::ast;
 
 use crate::{
     db::DefDatabase, Const, Enum, EnumVariant, FieldSource, Function, ImplBlock, Import, MacroDef,
-    Module, Static, Struct, StructField, Trait, TypeAlias, Union,
+    Module, Static, Struct, StructField, Trait, TypeAlias, TypeParam, Union,
 };
 
 pub use hir_expand::InFile;
@@ -129,3 +129,11 @@ impl HasSource for Import {
         src.with_value(ptr.map_left(|it| it.to_node(&root)).map_right(|it| it.to_node(&root)))
     }
 }
+
+impl HasSource for TypeParam {
+    type Ast = Either<ast::TraitDef, ast::TypeParam>;
+    fn source(self, db: &impl DefDatabase) -> InFile<Self::Ast> {
+        let child_source = self.id.parent.child_source(db);
+        child_source.map(|it| it[self.id.local_id].clone())
+    }
+}
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index 5cb222bd3..4acc038e4 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -1,9 +1,7 @@
 //! FIXME: write short doc here
-use either::Either;
-
 use hir_def::{
-    child_from_source::ChildFromSource, nameres::ModuleSource, AstItemDef, EnumVariantId, ImplId,
-    LocationCtx, ModuleId, TraitId, VariantId,
+    child_by_source::ChildBySource, dyn_map::DynMap, keys, nameres::ModuleSource, AstItemDef,
+    EnumVariantId, GenericDefId, LocationCtx, ModuleId, VariantId,
 };
 use hir_expand::{name::AsName, AstId, MacroDefId, MacroDefKind};
 use ra_syntax::{
@@ -14,7 +12,7 @@ use ra_syntax::{
 use crate::{
     db::{AstDatabase, DefDatabase, HirDatabase},
     Const, DefWithBody, Enum, EnumVariant, FieldSource, Function, ImplBlock, InFile, Local,
-    MacroDef, Module, Static, Struct, StructField, Trait, TypeAlias, Union,
+    MacroDef, Module, Static, Struct, StructField, Trait, TypeAlias, TypeParam, Union,
 };
 
 pub trait FromSource: Sized {
@@ -53,8 +51,9 @@ impl FromSource for Trait {
 impl FromSource for Function {
     type Ast = ast::FnDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: InFile<Self::Ast>) -> Option<Self> {
-        Container::find(db, src.as_ref().map(|it| it.syntax()))?
-            .child_from_source(db, src)
+        Container::find(db, src.as_ref().map(|it| it.syntax()))?.child_by_source(db)[keys::FUNCTION]
+            .get(&src)
+            .copied()
             .map(Function::from)
     }
 }
@@ -62,26 +61,29 @@ impl FromSource for Function {
 impl FromSource for Const {
     type Ast = ast::ConstDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: InFile<Self::Ast>) -> Option<Self> {
-        Container::find(db, src.as_ref().map(|it| it.syntax()))?
-            .child_from_source(db, src)
+        Container::find(db, src.as_ref().map(|it| it.syntax()))?.child_by_source(db)[keys::CONST]
+            .get(&src)
+            .copied()
             .map(Const::from)
     }
 }
 impl FromSource for Static {
     type Ast = ast::StaticDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: InFile<Self::Ast>) -> Option<Self> {
-        match Container::find(db, src.as_ref().map(|it| it.syntax()))? {
-            Container::Module(it) => it.id.child_from_source(db, src).map(Static::from),
-            Container::Trait(_) | Container::ImplBlock(_) => None,
-        }
+        Container::find(db, src.as_ref().map(|it| it.syntax()))?.child_by_source(db)[keys::STATIC]
+            .get(&src)
+            .copied()
+            .map(Static::from)
     }
 }
 
 impl FromSource for TypeAlias {
     type Ast = ast::TypeAliasDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: InFile<Self::Ast>) -> Option<Self> {
-        Container::find(db, src.as_ref().map(|it| it.syntax()))?
-            .child_from_source(db, src)
+        Container::find(db, src.as_ref().map(|it| it.syntax()))?.child_by_source(db)
+            [keys::TYPE_ALIAS]
+            .get(&src)
+            .copied()
             .map(TypeAlias::from)
     }
 }
@@ -116,32 +118,41 @@ impl FromSource for EnumVariant {
         let parent_enum = src.value.parent_enum();
         let src_enum = InFile { file_id: src.file_id, value: parent_enum };
         let parent_enum = Enum::from_source(db, src_enum)?;
-        parent_enum.id.child_from_source(db, src).map(EnumVariant::from)
+        parent_enum.id.child_by_source(db)[keys::ENUM_VARIANT]
+            .get(&src)
+            .copied()
+            .map(EnumVariant::from)
     }
 }
 
 impl FromSource for StructField {
     type Ast = FieldSource;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: InFile<Self::Ast>) -> Option<Self> {
+        let src = src.as_ref();
+
+        // FIXME this is buggy
         let variant_id: VariantId = match src.value {
-            FieldSource::Named(ref field) => {
+            FieldSource::Named(field) => {
                 let value = field.syntax().ancestors().find_map(ast::StructDef::cast)?;
                 let src = InFile { file_id: src.file_id, value };
                 let def = Struct::from_source(db, src)?;
                 def.id.into()
             }
-            FieldSource::Pos(ref field) => {
+            FieldSource::Pos(field) => {
                 let value = field.syntax().ancestors().find_map(ast::EnumVariant::cast)?;
                 let src = InFile { file_id: src.file_id, value };
                 let def = EnumVariant::from_source(db, src)?;
                 EnumVariantId::from(def).into()
             }
         };
-        let src = src.map(|field_source| match field_source {
-            FieldSource::Pos(it) => Either::Left(it),
-            FieldSource::Named(it) => Either::Right(it),
-        });
-        variant_id.child_from_source(db, src).map(StructField::from)
+
+        let dyn_map = variant_id.child_by_source(db);
+        match src.value {
+            FieldSource::Pos(it) => dyn_map[keys::TUPLE_FIELD].get(&src.with_value(it.clone())),
+            FieldSource::Named(it) => dyn_map[keys::RECORD_FIELD].get(&src.with_value(it.clone())),
+        }
+        .copied()
+        .map(StructField::from)
     }
 }
 
@@ -166,6 +177,28 @@ impl Local {
     }
 }
 
+impl TypeParam {
+    pub fn from_source(db: &impl HirDatabase, src: InFile<ast::TypeParam>) -> Option<Self> {
+        let file_id = src.file_id;
+        let parent: GenericDefId = src.value.syntax().ancestors().find_map(|it| {
+            let res = match_ast! {
+                match it {
+                    ast::FnDef(value) => { Function::from_source(db, InFile { value, file_id})?.id.into() },
+                    ast::StructDef(value) => { Struct::from_source(db, InFile { value, file_id})?.id.into() },
+                    ast::EnumDef(value) => { Enum::from_source(db, InFile { value, file_id})?.id.into() },
+                    ast::TraitDef(value) => { Trait::from_source(db, InFile { value, file_id})?.id.into() },
+                    ast::TypeAliasDef(value) => { TypeAlias::from_source(db, InFile { value, file_id})?.id.into() },
+                    ast::ImplBlock(value) => { ImplBlock::from_source(db, InFile { value, file_id})?.id.into() },
+                    _ => return None,
+                }
+            };
+            Some(res)
+        })?;
+        let &id = parent.child_by_source(db)[keys::TYPE_PARAM].get(&src)?;
+        Some(TypeParam { id })
+    }
+}
+
 impl Module {
     pub fn from_declaration(db: &impl DefDatabase, src: InFile<ast::Module>) -> Option<Self> {
         let parent_declaration = src.value.syntax().ancestors().skip(1).find_map(ast::Module::cast);
@@ -255,21 +288,12 @@ impl Container {
     }
 }
 
-impl<CHILD, SOURCE> ChildFromSource<CHILD, SOURCE> for Container
-where
-    TraitId: ChildFromSource<CHILD, SOURCE>,
-    ImplId: ChildFromSource<CHILD, SOURCE>,
-    ModuleId: ChildFromSource<CHILD, SOURCE>,
-{
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<SOURCE>,
-    ) -> Option<CHILD> {
+impl ChildBySource for Container {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
         match self {
-            Container::Trait(it) => it.id.child_from_source(db, child_source),
-            Container::ImplBlock(it) => it.id.child_from_source(db, child_source),
-            Container::Module(it) => it.id.child_from_source(db, child_source),
+            Container::Trait(it) => it.id.child_by_source(db),
+            Container::ImplBlock(it) => it.id.child_by_source(db),
+            Container::Module(it) => it.id.child_by_source(db),
         }
     }
 }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index f12e4ca3f..9eb34b5dc 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -42,9 +42,9 @@ pub mod from_source;
 pub use crate::{
     code_model::{
         src::HasSource, Adt, AssocItem, AttrDef, Const, Container, Crate, CrateDependency,
-        DefWithBody, Docs, Enum, EnumVariant, FieldSource, Function, GenericDef, GenericParam,
-        HasAttrs, ImplBlock, Import, Local, MacroDef, Module, ModuleDef, ScopeDef, Static, Struct,
-        StructField, Trait, Type, TypeAlias, Union, VariantDef,
+        DefWithBody, Docs, Enum, EnumVariant, FieldSource, Function, GenericDef, HasAttrs,
+        ImplBlock, Import, Local, MacroDef, Module, ModuleDef, ScopeDef, Static, Struct,
+        StructField, Trait, Type, TypeAlias, TypeParam, Union, VariantDef,
     },
     from_source::FromSource,
     source_binder::{PathResolution, ScopeEntryWithSyntax, SourceAnalyzer},
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 42c392513..c5a920688 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -21,7 +21,6 @@ use hir_def::{
 };
 use hir_expand::{
     hygiene::Hygiene, name::AsName, AstId, HirFileId, InFile, MacroCallId, MacroCallKind,
-    MacroFileKind,
 };
 use ra_syntax::{
     ast::{self, AstNode},
@@ -36,8 +35,8 @@ use crate::{
         method_resolution::{self, implements_trait},
         InEnvironment, TraitEnvironment, Ty,
     },
-    Adt, AssocItem, Const, DefWithBody, Enum, EnumVariant, FromSource, Function, GenericParam,
-    Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Type, TypeAlias,
+    Adt, AssocItem, Const, DefWithBody, Enum, EnumVariant, FromSource, Function, ImplBlock, Local,
+    MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Type, TypeAlias, TypeParam,
 };
 
 fn try_get_resolver_for_node(db: &impl HirDatabase, node: InFile<&SyntaxNode>) -> Option<Resolver> {
@@ -59,6 +58,10 @@ fn try_get_resolver_for_node(db: &impl HirDatabase, node: InFile<&SyntaxNode>) -
                 let src = node.with_value(it);
                 Some(Enum::from_source(db, src)?.id.resolver(db))
             },
+            ast::ImplBlock(it) => {
+                let src = node.with_value(it);
+                Some(ImplBlock::from_source(db, src)?.id.resolver(db))
+            },
             _ => match node.value.kind() {
                 FN_DEF | CONST_DEF | STATIC_DEF => {
                     let def = def_with_body_from_child_node(db, node)?;
@@ -76,12 +79,13 @@ fn def_with_body_from_child_node(
     db: &impl HirDatabase,
     child: InFile<&SyntaxNode>,
 ) -> Option<DefWithBody> {
-    child.value.ancestors().find_map(|node| {
+    child.cloned().ancestors_with_macros(db).find_map(|node| {
+        let n = &node.value;
         match_ast! {
-            match node {
-                ast::FnDef(def)  => { return Function::from_source(db, child.with_value(def)).map(DefWithBody::from); },
-                ast::ConstDef(def) => { return Const::from_source(db, child.with_value(def)).map(DefWithBody::from); },
-                ast::StaticDef(def) => { return Static::from_source(db, child.with_value(def)).map(DefWithBody::from); },
+            match n {
+                ast::FnDef(def)  => { return Function::from_source(db, node.with_value(def)).map(DefWithBody::from); },
+                ast::ConstDef(def) => { return Const::from_source(db, node.with_value(def)).map(DefWithBody::from); },
+                ast::StaticDef(def) => { return Static::from_source(db, node.with_value(def)).map(DefWithBody::from); },
                 _ => { None },
             }
         }
@@ -107,7 +111,7 @@ pub enum PathResolution {
     /// A local binding (only value namespace)
     Local(Local),
     /// A generic parameter
-    GenericParam(GenericParam),
+    TypeParam(TypeParam),
     SelfType(crate::ImplBlock),
     Macro(MacroDef),
     AssocItem(crate::AssocItem),
@@ -135,8 +139,8 @@ pub struct ReferenceDescriptor {
     pub name: String,
 }
 
+#[derive(Debug)]
 pub struct Expansion {
-    macro_file_kind: MacroFileKind,
     macro_call_id: MacroCallId,
 }
 
@@ -151,7 +155,7 @@ impl Expansion {
     }
 
     pub fn file_id(&self) -> HirFileId {
-        self.macro_call_id.as_file(self.macro_file_kind)
+        self.macro_call_id.as_file()
     }
 }
 
@@ -260,10 +264,7 @@ impl SourceAnalyzer {
     ) -> Option<PathResolution> {
         let types = self.resolver.resolve_path_in_type_ns_fully(db, &path).map(|ty| match ty {
             TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
-            TypeNs::GenericParam(idx) => PathResolution::GenericParam(GenericParam {
-                parent: self.resolver.generic_def().unwrap(),
-                idx,
-            }),
+            TypeNs::GenericParam(id) => PathResolution::TypeParam(TypeParam { id }),
             TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => {
                 PathResolution::Def(Adt::from(it).into())
             }
@@ -335,10 +336,7 @@ impl SourceAnalyzer {
                 resolver::ScopeDef::PerNs(it) => it.into(),
                 resolver::ScopeDef::ImplSelfType(it) => ScopeDef::ImplSelfType(it.into()),
                 resolver::ScopeDef::AdtSelfType(it) => ScopeDef::AdtSelfType(it.into()),
-                resolver::ScopeDef::GenericParam(idx) => {
-                    let parent = self.resolver.generic_def().unwrap();
-                    ScopeDef::GenericParam(GenericParam { parent, idx })
-                }
+                resolver::ScopeDef::GenericParam(id) => ScopeDef::GenericParam(TypeParam { id }),
                 resolver::ScopeDef::Local(pat_id) => {
                     let parent = self.resolver.body_owner().unwrap().into();
                     ScopeDef::Local(Local { parent, pat_id })
@@ -456,10 +454,7 @@ impl SourceAnalyzer {
             macro_call.file_id,
             db.ast_id_map(macro_call.file_id).ast_id(macro_call.value),
         );
-        Some(Expansion {
-            macro_call_id: def.as_call_id(db, MacroCallKind::FnLike(ast_id)),
-            macro_file_kind: to_macro_file_kind(macro_call.value),
-        })
+        Some(Expansion { macro_call_id: def.as_call_id(db, MacroCallKind::FnLike(ast_id)) })
     }
 }
 
@@ -543,35 +538,3 @@ fn adjust(
         })
         .map(|(_ptr, scope)| *scope)
 }
-
-/// Given a `ast::MacroCall`, return what `MacroKindFile` it belongs to.
-/// FIXME: Not completed
-fn to_macro_file_kind(macro_call: &ast::MacroCall) -> MacroFileKind {
-    let syn = macro_call.syntax();
-    let parent = match syn.parent() {
-        Some(it) => it,
-        None => {
-            // FIXME:
-            // If it is root, which means the parent HirFile
-            // MacroKindFile must be non-items
-            // return expr now.
-            return MacroFileKind::Expr;
-        }
-    };
-
-    match parent.kind() {
-        MACRO_ITEMS | SOURCE_FILE => MacroFileKind::Items,
-        LET_STMT => {
-            // FIXME: Handle Pattern
-            MacroFileKind::Expr
-        }
-        EXPR_STMT => MacroFileKind::Statements,
-        BLOCK => MacroFileKind::Statements,
-        ARG_LIST => MacroFileKind::Expr,
-        TRY_EXPR => MacroFileKind::Expr,
-        _ => {
-            // Unknown , Just guess it is `Items`
-            MacroFileKind::Items
-        }
-    }
-}
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index cf3a446fc..b1923bbf2 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -12,6 +12,7 @@ log = "0.4.5"
 once_cell = "1.0.1"
 rustc-hash = "1.0"
 either = "1.5"
+anymap = "0.12"
 
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index 7b385f3fd..b3bc336cf 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -6,9 +6,7 @@ pub mod scope;
 use std::{ops::Index, sync::Arc};
 
 use either::Either;
-use hir_expand::{
-    hygiene::Hygiene, AstId, HirFileId, InFile, MacroCallKind, MacroDefId, MacroFileKind,
-};
+use hir_expand::{hygiene::Hygiene, AstId, HirFileId, InFile, MacroCallKind, MacroDefId};
 use ra_arena::{map::ArenaMap, Arena};
 use ra_syntax::{ast, AstNode, AstPtr};
 use rustc_hash::FxHashMap;
@@ -49,7 +47,7 @@ impl Expander {
         if let Some(path) = macro_call.path().and_then(|path| self.parse_path(path)) {
             if let Some(def) = self.resolve_path_as_macro(db, &path) {
                 let call_id = def.as_call_id(db, MacroCallKind::FnLike(ast_id));
-                let file_id = call_id.as_file(MacroFileKind::Expr);
+                let file_id = call_id.as_file();
                 if let Some(node) = db.parse_or_expand(file_id) {
                     if let Some(expr) = ast::Expr::cast(node) {
                         log::debug!("macro expansion {:#?}", expr.syntax());
diff --git a/crates/ra_hir_def/src/child_by_source.rs b/crates/ra_hir_def/src/child_by_source.rs
new file mode 100644
index 000000000..a3574a9db
--- /dev/null
+++ b/crates/ra_hir_def/src/child_by_source.rs
@@ -0,0 +1,139 @@
+//! When *constructing* `hir`, we start at some parent syntax node and recursively
+//! lower the children.
+//!
+//! This modules allows one to go in the opposite direction: start with a syntax
+//! node for a *child*, and get its hir.
+
+use either::Either;
+
+use crate::{
+    db::DefDatabase,
+    dyn_map::DynMap,
+    keys,
+    src::{HasChildSource, HasSource},
+    AssocItemId, EnumId, EnumVariantId, ImplId, Lookup, ModuleDefId, ModuleId, StructFieldId,
+    TraitId, VariantId,
+};
+
+pub trait ChildBySource {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap;
+}
+
+impl ChildBySource for TraitId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+
+        let data = db.trait_data(*self);
+        for (_name, item) in data.items.iter() {
+            match *item {
+                AssocItemId::FunctionId(func) => {
+                    let src = func.lookup(db).source(db);
+                    res[keys::FUNCTION].insert(src, func)
+                }
+                AssocItemId::ConstId(konst) => {
+                    let src = konst.lookup(db).source(db);
+                    res[keys::CONST].insert(src, konst)
+                }
+                AssocItemId::TypeAliasId(ty) => {
+                    let src = ty.lookup(db).source(db);
+                    res[keys::TYPE_ALIAS].insert(src, ty)
+                }
+            }
+        }
+
+        res
+    }
+}
+
+impl ChildBySource for ImplId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+
+        let data = db.impl_data(*self);
+        for &item in data.items.iter() {
+            match item {
+                AssocItemId::FunctionId(func) => {
+                    let src = func.lookup(db).source(db);
+                    res[keys::FUNCTION].insert(src, func)
+                }
+                AssocItemId::ConstId(konst) => {
+                    let src = konst.lookup(db).source(db);
+                    res[keys::CONST].insert(src, konst)
+                }
+                AssocItemId::TypeAliasId(ty) => {
+                    let src = ty.lookup(db).source(db);
+                    res[keys::TYPE_ALIAS].insert(src, ty)
+                }
+            }
+        }
+
+        res
+    }
+}
+
+impl ChildBySource for ModuleId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+
+        let crate_def_map = db.crate_def_map(self.krate);
+        for item in crate_def_map[self.local_id].scope.declarations() {
+            match item {
+                ModuleDefId::FunctionId(func) => {
+                    let src = func.lookup(db).source(db);
+                    res[keys::FUNCTION].insert(src, func)
+                }
+                ModuleDefId::ConstId(konst) => {
+                    let src = konst.lookup(db).source(db);
+                    res[keys::CONST].insert(src, konst)
+                }
+                ModuleDefId::StaticId(statik) => {
+                    let src = statik.lookup(db).source(db);
+                    res[keys::STATIC].insert(src, statik)
+                }
+                ModuleDefId::TypeAliasId(ty) => {
+                    let src = ty.lookup(db).source(db);
+                    res[keys::TYPE_ALIAS].insert(src, ty)
+                }
+                _ => (),
+            }
+        }
+
+        res
+    }
+}
+
+impl ChildBySource for VariantId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+
+        let arena_map = self.child_source(db);
+        let arena_map = arena_map.as_ref();
+        for (local_id, source) in arena_map.value.iter() {
+            let id = StructFieldId { parent: *self, local_id };
+            match source {
+                Either::Left(source) => {
+                    res[keys::TUPLE_FIELD].insert(arena_map.with_value(source.clone()), id)
+                }
+                Either::Right(source) => {
+                    res[keys::RECORD_FIELD].insert(arena_map.with_value(source.clone()), id)
+                }
+            }
+        }
+        res
+    }
+}
+
+impl ChildBySource for EnumId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+
+        let arena_map = self.child_source(db);
+        let arena_map = arena_map.as_ref();
+        for (local_id, source) in arena_map.value.iter() {
+            let id = EnumVariantId { parent: *self, local_id };
+            res[keys::ENUM_VARIANT].insert(arena_map.with_value(source.clone()), id)
+        }
+
+        res
+    }
+}
diff --git a/crates/ra_hir_def/src/child_from_source.rs b/crates/ra_hir_def/src/child_from_source.rs
deleted file mode 100644
index 37d4b7870..000000000
--- a/crates/ra_hir_def/src/child_from_source.rs
+++ /dev/null
@@ -1,276 +0,0 @@
-//! When *constructing* `hir`, we start at some parent syntax node and recursively
-//! lower the children.
-//!
-//! This modules allows one to go in the opposite direction: start with a syntax
-//! node for a *child*, and get its hir.
-
-use either::Either;
-use hir_expand::InFile;
-use ra_syntax::{ast, AstNode, AstPtr};
-
-use crate::{
-    db::DefDatabase,
-    src::{HasChildSource, HasSource},
-    AssocItemId, ConstId, EnumId, EnumVariantId, FunctionId, ImplId, Lookup, ModuleDefId, ModuleId,
-    StaticId, StructFieldId, TraitId, TypeAliasId, VariantId,
-};
-
-pub trait ChildFromSource<CHILD, SOURCE> {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<SOURCE>,
-    ) -> Option<CHILD>;
-}
-
-impl ChildFromSource<FunctionId, ast::FnDef> for TraitId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::FnDef>,
-    ) -> Option<FunctionId> {
-        let data = db.trait_data(*self);
-        data.items
-            .iter()
-            .filter_map(|(_, item)| match item {
-                AssocItemId::FunctionId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<FunctionId, ast::FnDef> for ImplId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::FnDef>,
-    ) -> Option<FunctionId> {
-        let data = db.impl_data(*self);
-        data.items
-            .iter()
-            .filter_map(|item| match item {
-                AssocItemId::FunctionId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<FunctionId, ast::FnDef> for ModuleId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::FnDef>,
-    ) -> Option<FunctionId> {
-        let crate_def_map = db.crate_def_map(self.krate);
-        let res = crate_def_map[self.local_id]
-            .scope
-            .declarations()
-            .filter_map(|item| match item {
-                ModuleDefId::FunctionId(it) => Some(it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            });
-        res
-    }
-}
-
-impl ChildFromSource<ConstId, ast::ConstDef> for TraitId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::ConstDef>,
-    ) -> Option<ConstId> {
-        let data = db.trait_data(*self);
-        data.items
-            .iter()
-            .filter_map(|(_, item)| match item {
-                AssocItemId::ConstId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<ConstId, ast::ConstDef> for ImplId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::ConstDef>,
-    ) -> Option<ConstId> {
-        let data = db.impl_data(*self);
-        data.items
-            .iter()
-            .filter_map(|item| match item {
-                AssocItemId::ConstId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<ConstId, ast::ConstDef> for ModuleId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::ConstDef>,
-    ) -> Option<ConstId> {
-        let crate_def_map = db.crate_def_map(self.krate);
-        let res = crate_def_map[self.local_id]
-            .scope
-            .declarations()
-            .filter_map(|item| match item {
-                ModuleDefId::ConstId(it) => Some(it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            });
-        res
-    }
-}
-
-impl ChildFromSource<TypeAliasId, ast::TypeAliasDef> for TraitId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::TypeAliasDef>,
-    ) -> Option<TypeAliasId> {
-        let data = db.trait_data(*self);
-        data.items
-            .iter()
-            .filter_map(|(_, item)| match item {
-                AssocItemId::TypeAliasId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<TypeAliasId, ast::TypeAliasDef> for ImplId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::TypeAliasDef>,
-    ) -> Option<TypeAliasId> {
-        let data = db.impl_data(*self);
-        data.items
-            .iter()
-            .filter_map(|item| match item {
-                AssocItemId::TypeAliasId(it) => Some(*it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            })
-    }
-}
-
-impl ChildFromSource<TypeAliasId, ast::TypeAliasDef> for ModuleId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::TypeAliasDef>,
-    ) -> Option<TypeAliasId> {
-        let crate_def_map = db.crate_def_map(self.krate);
-        let res = crate_def_map[self.local_id]
-            .scope
-            .declarations()
-            .filter_map(|item| match item {
-                ModuleDefId::TypeAliasId(it) => Some(it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            });
-        res
-    }
-}
-
-impl ChildFromSource<StaticId, ast::StaticDef> for ModuleId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::StaticDef>,
-    ) -> Option<StaticId> {
-        let crate_def_map = db.crate_def_map(self.krate);
-        let res = crate_def_map[self.local_id]
-            .scope
-            .declarations()
-            .filter_map(|item| match item {
-                ModuleDefId::StaticId(it) => Some(it),
-                _ => None,
-            })
-            .find(|func| {
-                let source = func.lookup(db).source(db);
-                same_source(&source, &child_source)
-            });
-        res
-    }
-}
-
-impl ChildFromSource<StructFieldId, Either<ast::TupleFieldDef, ast::RecordFieldDef>> for VariantId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<Either<ast::TupleFieldDef, ast::RecordFieldDef>>,
-    ) -> Option<StructFieldId> {
-        let arena_map = self.child_source(db);
-        let (local_id, _) = arena_map.as_ref().value.iter().find(|(_local_id, source)| {
-            child_source.file_id == arena_map.file_id
-                && match (source, &child_source.value) {
-                    (Either::Left(a), Either::Left(b)) => AstPtr::new(a) == AstPtr::new(b),
-                    (Either::Right(a), Either::Right(b)) => AstPtr::new(a) == AstPtr::new(b),
-                    _ => false,
-                }
-        })?;
-        Some(StructFieldId { parent: *self, local_id })
-    }
-}
-
-impl ChildFromSource<EnumVariantId, ast::EnumVariant> for EnumId {
-    fn child_from_source(
-        &self,
-        db: &impl DefDatabase,
-        child_source: InFile<ast::EnumVariant>,
-    ) -> Option<EnumVariantId> {
-        let arena_map = self.child_source(db);
-        let (local_id, _) = arena_map.as_ref().value.iter().find(|(_local_id, source)| {
-            child_source.file_id == arena_map.file_id
-                && AstPtr::new(*source) == AstPtr::new(&child_source.value)
-        })?;
-        Some(EnumVariantId { parent: *self, local_id })
-    }
-}
-
-/// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
-/// equal if they point to exactly the same object.
-///
-/// In general, we do not guarantee that we have exactly one instance of a
-/// syntax tree for each file. We probably should add such guarantee, but, for
-/// the time being, we will use identity-less AstPtr comparison.
-fn same_source<N: AstNode>(s1: &InFile<N>, s2: &InFile<N>) -> bool {
-    s1.as_ref().map(AstPtr::new) == s2.as_ref().map(AstPtr::new)
-}
diff --git a/crates/ra_hir_def/src/dyn_map.rs b/crates/ra_hir_def/src/dyn_map.rs
new file mode 100644
index 000000000..6f269d7b0
--- /dev/null
+++ b/crates/ra_hir_def/src/dyn_map.rs
@@ -0,0 +1,108 @@
+//! This module defines a `DynMap` -- a container for heterogeneous maps.
+//!
+//! This means that `DynMap` stores a bunch of hash maps inside, and those maps
+//! can be of different types.
+//!
+//! It is used like this:
+//!
+//! ```
+//! // keys define submaps of a `DynMap`
+//! const STRING_TO_U32: Key<String, u32> = Key::new();
+//! const U32_TO_VEC: Key<u32, Vec<bool>> = Key::new();
+//!
+//! // Note: concrete type, no type params!
+//! let mut map = DynMap::new();
+//!
+//! // To access a specific map, index the `DynMap` by `Key`:
+//! map[STRING_TO_U32].insert("hello".to_string(), 92);
+//! let value = map[U32_TO_VEC].get(92);
+//! assert!(value.is_none());
+//! ```
+//!
+//! This is a work of fiction. Any similarities to Kotlin's `BindingContext` are
+//! a coincidence.
+use std::{
+    hash::Hash,
+    marker::PhantomData,
+    ops::{Index, IndexMut},
+};
+
+use anymap::Map;
+use rustc_hash::FxHashMap;
+
+pub struct Key<K, V, P = (K, V)> {
+    _phantom: PhantomData<(K, V, P)>,
+}
+
+impl<K, V, P> Key<K, V, P> {
+    pub(crate) const fn new() -> Key<K, V, P> {
+        Key { _phantom: PhantomData }
+    }
+}
+
+impl<K, V, P> Copy for Key<K, V, P> {}
+
+impl<K, V, P> Clone for Key<K, V, P> {
+    fn clone(&self) -> Key<K, V, P> {
+        *self
+    }
+}
+
+pub trait Policy {
+    type K;
+    type V;
+
+    fn insert(map: &mut DynMap, key: Self::K, value: Self::V);
+    fn get<'a>(map: &'a DynMap, key: &Self::K) -> Option<&'a Self::V>;
+}
+
+impl<K: Hash + Eq + 'static, V: 'static> Policy for (K, V) {
+    type K = K;
+    type V = V;
+    fn insert(map: &mut DynMap, key: K, value: V) {
+        map.map.entry::<FxHashMap<K, V>>().or_insert_with(Default::default).insert(key, value);
+    }
+    fn get<'a>(map: &'a DynMap, key: &K) -> Option<&'a V> {
+        map.map.get::<FxHashMap<K, V>>()?.get(key)
+    }
+}
+
+pub struct DynMap {
+    pub(crate) map: Map,
+}
+
+impl Default for DynMap {
+    fn default() -> Self {
+        DynMap { map: Map::new() }
+    }
+}
+
+#[repr(transparent)]
+pub struct KeyMap<KEY> {
+    map: DynMap,
+    _phantom: PhantomData<KEY>,
+}
+
+impl<P: Policy> KeyMap<Key<P::K, P::V, P>> {
+    pub fn insert(&mut self, key: P::K, value: P::V) {
+        P::insert(&mut self.map, key, value)
+    }
+    pub fn get(&self, key: &P::K) -> Option<&P::V> {
+        P::get(&self.map, key)
+    }
+}
+
+impl<P: Policy> Index<Key<P::K, P::V, P>> for DynMap {
+    type Output = KeyMap<Key<P::K, P::V, P>>;
+    fn index(&self, _key: Key<P::K, P::V, P>) -> &Self::Output {
+        // Safe due to `#[repr(transparent)]`.
+        unsafe { std::mem::transmute::<&DynMap, &KeyMap<Key<P::K, P::V, P>>>(self) }
+    }
+}
+
+impl<P: Policy> IndexMut<Key<P::K, P::V, P>> for DynMap {
+    fn index_mut(&mut self, _key: Key<P::K, P::V, P>) -> &mut Self::Output {
+        // Safe due to `#[repr(transparent)]`.
+        unsafe { std::mem::transmute::<&mut DynMap, &mut KeyMap<Key<P::K, P::V, P>>>(self) }
+    }
+}
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index 5f648ffc3..976cf72d0 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -4,21 +4,29 @@
 //! in rustc.
 use std::sync::Arc;
 
-use hir_expand::name::{self, AsName, Name};
+use either::Either;
+use hir_expand::{
+    name::{self, AsName, Name},
+    InFile,
+};
+use ra_arena::{map::ArenaMap, Arena};
+use ra_db::FileId;
 use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 
 use crate::{
+    child_by_source::ChildBySource,
     db::DefDatabase,
+    dyn_map::DynMap,
+    keys,
+    src::HasChildSource,
     src::HasSource,
     type_ref::{TypeBound, TypeRef},
-    AdtId, AstItemDef, ContainerId, GenericDefId, Lookup,
+    AdtId, AstItemDef, GenericDefId, LocalTypeParamId, Lookup, TypeParamId,
 };
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
 #[derive(Clone, PartialEq, Eq, Debug)]
-pub struct GenericParam {
-    // FIXME: give generic params proper IDs
-    pub idx: u32,
+pub struct TypeParamData {
     pub name: Name,
     pub default: Option<TypeRef>,
 }
@@ -26,8 +34,8 @@ pub struct GenericParam {
 /// Data about the generic parameters of a function, struct, impl, etc.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct GenericParams {
-    pub parent_params: Option<Arc<GenericParams>>,
-    pub params: Vec<GenericParam>,
+    pub types: Arena<LocalTypeParamId, TypeParamData>,
+    // lifetimes: Arena<LocalLifetimeParamId, LifetimeParamData>,
     pub where_predicates: Vec<WherePredicate>,
 }
 
@@ -41,63 +49,87 @@ pub struct WherePredicate {
     pub bound: TypeBound,
 }
 
+type SourceMap = ArenaMap<LocalTypeParamId, Either<ast::TraitDef, ast::TypeParam>>;
+
 impl GenericParams {
     pub(crate) fn generic_params_query(
         db: &impl DefDatabase,
         def: GenericDefId,
     ) -> Arc<GenericParams> {
-        let parent_generics = parent_generic_def(db, def).map(|it| db.generic_params(it));
-        Arc::new(GenericParams::new(db, def.into(), parent_generics))
+        let (params, _source_map) = GenericParams::new(db, def.into());
+        Arc::new(params)
     }
 
-    fn new(
-        db: &impl DefDatabase,
-        def: GenericDefId,
-        parent_params: Option<Arc<GenericParams>>,
-    ) -> GenericParams {
-        let mut generics =
-            GenericParams { params: Vec::new(), parent_params, where_predicates: Vec::new() };
-        let start = generics.parent_params.as_ref().map(|p| p.params.len()).unwrap_or(0) as u32;
+    fn new(db: &impl DefDatabase, def: GenericDefId) -> (GenericParams, InFile<SourceMap>) {
+        let mut generics = GenericParams { types: Arena::default(), where_predicates: Vec::new() };
+        let mut sm = ArenaMap::default();
         // FIXME: add `: Sized` bound for everything except for `Self` in traits
-        match def {
-            GenericDefId::FunctionId(it) => generics.fill(&it.lookup(db).source(db).value, start),
-            GenericDefId::AdtId(AdtId::StructId(it)) => generics.fill(&it.source(db).value, start),
-            GenericDefId::AdtId(AdtId::UnionId(it)) => generics.fill(&it.source(db).value, start),
-            GenericDefId::AdtId(AdtId::EnumId(it)) => generics.fill(&it.source(db).value, start),
+        let file_id = match def {
+            GenericDefId::FunctionId(it) => {
+                let src = it.lookup(db).source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
+            GenericDefId::AdtId(AdtId::StructId(it)) => {
+                let src = it.source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
+            GenericDefId::AdtId(AdtId::UnionId(it)) => {
+                let src = it.source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
+            GenericDefId::AdtId(AdtId::EnumId(it)) => {
+                let src = it.source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
             GenericDefId::TraitId(it) => {
+                let src = it.source(db);
+
                 // traits get the Self type as an implicit first type parameter
-                generics.params.push(GenericParam {
-                    idx: start,
-                    name: name::SELF_TYPE,
-                    default: None,
-                });
-                generics.fill(&it.source(db).value, start + 1);
+                let self_param_id =
+                    generics.types.alloc(TypeParamData { name: name::SELF_TYPE, default: None });
+                sm.insert(self_param_id, Either::Left(src.value.clone()));
                 // add super traits as bounds on Self
                 // i.e., trait Foo: Bar is equivalent to trait Foo where Self: Bar
                 let self_param = TypeRef::Path(name::SELF_TYPE.into());
-                generics.fill_bounds(&it.source(db).value, self_param);
+                generics.fill_bounds(&src.value, self_param);
+
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
+            GenericDefId::TypeAliasId(it) => {
+                let src = it.lookup(db).source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
             }
-            GenericDefId::TypeAliasId(it) => generics.fill(&it.lookup(db).source(db).value, start),
             // Note that we don't add `Self` here: in `impl`s, `Self` is not a
             // type-parameter, but rather is a type-alias for impl's target
             // type, so this is handled by the resolver.
-            GenericDefId::ImplId(it) => generics.fill(&it.source(db).value, start),
-            GenericDefId::EnumVariantId(_) | GenericDefId::ConstId(_) => {}
-        }
+            GenericDefId::ImplId(it) => {
+                let src = it.source(db);
+                generics.fill(&mut sm, &src.value);
+                src.file_id
+            }
+            // We won't be using this ID anyway
+            GenericDefId::EnumVariantId(_) | GenericDefId::ConstId(_) => FileId(!0).into(),
+        };
 
-        generics
+        (generics, InFile::new(file_id, sm))
     }
 
-    fn fill(&mut self, node: &impl TypeParamsOwner, start: u32) {
+    fn fill(&mut self, sm: &mut SourceMap, node: &dyn TypeParamsOwner) {
         if let Some(params) = node.type_param_list() {
-            self.fill_params(params, start)
+            self.fill_params(sm, params)
         }
         if let Some(where_clause) = node.where_clause() {
             self.fill_where_predicates(where_clause);
         }
     }
 
-    fn fill_bounds(&mut self, node: &impl ast::TypeBoundsOwner, type_ref: TypeRef) {
+    fn fill_bounds(&mut self, node: &dyn ast::TypeBoundsOwner, type_ref: TypeRef) {
         for bound in
             node.type_bound_list().iter().flat_map(|type_bound_list| type_bound_list.bounds())
         {
@@ -105,13 +137,14 @@ impl GenericParams {
         }
     }
 
-    fn fill_params(&mut self, params: ast::TypeParamList, start: u32) {
-        for (idx, type_param) in params.type_params().enumerate() {
+    fn fill_params(&mut self, sm: &mut SourceMap, params: ast::TypeParamList) {
+        for type_param in params.type_params() {
             let name = type_param.name().map_or_else(Name::missing, |it| it.as_name());
             // FIXME: Use `Path::from_src`
             let default = type_param.default_type().map(TypeRef::from_ast);
-            let param = GenericParam { idx: idx as u32 + start, name: name.clone(), default };
-            self.params.push(param);
+            let param = TypeParamData { name: name.clone(), default };
+            let param_id = self.types.alloc(param);
+            sm.insert(param_id, Either::Right(type_param.clone()));
 
             let type_ref = TypeRef::Path(name.into());
             self.fill_bounds(&type_param, type_ref);
@@ -140,45 +173,31 @@ impl GenericParams {
         self.where_predicates.push(WherePredicate { type_ref, bound });
     }
 
-    pub fn find_by_name(&self, name: &Name) -> Option<&GenericParam> {
-        self.params.iter().find(|p| &p.name == name)
-    }
-
-    pub fn count_parent_params(&self) -> usize {
-        self.parent_params.as_ref().map(|p| p.count_params_including_parent()).unwrap_or(0)
-    }
-
-    pub fn count_params_including_parent(&self) -> usize {
-        let parent_count = self.count_parent_params();
-        parent_count + self.params.len()
-    }
-
-    fn for_each_param<'a>(&'a self, f: &mut impl FnMut(&'a GenericParam)) {
-        if let Some(parent) = &self.parent_params {
-            parent.for_each_param(f);
-        }
-        self.params.iter().for_each(f);
+    pub fn find_by_name(&self, name: &Name) -> Option<LocalTypeParamId> {
+        self.types.iter().find_map(|(id, p)| if &p.name == name { Some(id) } else { None })
     }
+}
 
-    pub fn params_including_parent(&self) -> Vec<&GenericParam> {
-        let mut vec = Vec::with_capacity(self.count_params_including_parent());
-        self.for_each_param(&mut |p| vec.push(p));
-        vec
+impl HasChildSource for GenericDefId {
+    type ChildId = LocalTypeParamId;
+    type Value = Either<ast::TraitDef, ast::TypeParam>;
+    fn child_source(&self, db: &impl DefDatabase) -> InFile<SourceMap> {
+        let (_, sm) = GenericParams::new(db, *self);
+        sm
     }
 }
 
-fn parent_generic_def(db: &impl DefDatabase, def: GenericDefId) -> Option<GenericDefId> {
-    let container = match def {
-        GenericDefId::FunctionId(it) => it.lookup(db).container,
-        GenericDefId::TypeAliasId(it) => it.lookup(db).container,
-        GenericDefId::ConstId(it) => it.lookup(db).container,
-        GenericDefId::EnumVariantId(it) => return Some(it.parent.into()),
-        GenericDefId::AdtId(_) | GenericDefId::TraitId(_) | GenericDefId::ImplId(_) => return None,
-    };
-
-    match container {
-        ContainerId::ImplId(it) => Some(it.into()),
-        ContainerId::TraitId(it) => Some(it.into()),
-        ContainerId::ModuleId(_) => None,
+impl ChildBySource for GenericDefId {
+    fn child_by_source(&self, db: &impl DefDatabase) -> DynMap {
+        let mut res = DynMap::default();
+        let arena_map = self.child_source(db);
+        let arena_map = arena_map.as_ref();
+        for (local_id, src) in arena_map.value.iter() {
+            let id = TypeParamId { parent: *self, local_id };
+            if let Either::Right(type_param) = src {
+                res[keys::TYPE_PARAM].insert(arena_map.with_value(type_param.clone()), id)
+            }
+        }
+        res
     }
 }
diff --git a/crates/ra_hir_def/src/keys.rs b/crates/ra_hir_def/src/keys.rs
new file mode 100644
index 000000000..be702a4f8
--- /dev/null
+++ b/crates/ra_hir_def/src/keys.rs
@@ -0,0 +1,49 @@
+//! keys to be used with `DynMap`
+
+use std::marker::PhantomData;
+
+use hir_expand::InFile;
+use ra_syntax::{ast, AstNode, AstPtr};
+use rustc_hash::FxHashMap;
+
+use crate::{
+    dyn_map::{DynMap, Policy},
+    ConstId, EnumVariantId, FunctionId, StaticId, StructFieldId, TypeAliasId, TypeParamId,
+};
+
+type Key<K, V> = crate::dyn_map::Key<InFile<K>, V, AstPtrPolicy<K, V>>;
+
+pub const FUNCTION: Key<ast::FnDef, FunctionId> = Key::new();
+pub const CONST: Key<ast::ConstDef, ConstId> = Key::new();
+pub const STATIC: Key<ast::StaticDef, StaticId> = Key::new();
+pub const ENUM_VARIANT: Key<ast::EnumVariant, EnumVariantId> = Key::new();
+pub const TYPE_ALIAS: Key<ast::TypeAliasDef, TypeAliasId> = Key::new();
+pub const TUPLE_FIELD: Key<ast::TupleFieldDef, StructFieldId> = Key::new();
+pub const RECORD_FIELD: Key<ast::RecordFieldDef, StructFieldId> = Key::new();
+pub const TYPE_PARAM: Key<ast::TypeParam, TypeParamId> = Key::new();
+
+/// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
+/// equal if they point to exactly the same object.
+///
+/// In general, we do not guarantee that we have exactly one instance of a
+/// syntax tree for each file. We probably should add such guarantee, but, for
+/// the time being, we will use identity-less AstPtr comparison.
+pub struct AstPtrPolicy<AST, ID> {
+    _phantom: PhantomData<(AST, ID)>,
+}
+
+impl<AST: AstNode + 'static, ID: 'static> Policy for AstPtrPolicy<AST, ID> {
+    type K = InFile<AST>;
+    type V = ID;
+    fn insert(map: &mut DynMap, key: InFile<AST>, value: ID) {
+        let key = key.as_ref().map(AstPtr::new);
+        map.map
+            .entry::<FxHashMap<InFile<AstPtr<AST>>, ID>>()
+            .or_insert_with(Default::default)
+            .insert(key, value);
+    }
+    fn get<'a>(map: &'a DynMap, key: &InFile<AST>) -> Option<&'a ID> {
+        let key = key.as_ref().map(AstPtr::new);
+        map.map.get::<FxHashMap<InFile<AstPtr<AST>>, ID>>()?.get(&key)
+    }
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index e02622f62..569da4f28 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -16,6 +16,9 @@ pub mod builtin_type;
 pub mod diagnostics;
 pub mod per_ns;
 
+pub mod dyn_map;
+pub mod keys;
+
 pub mod adt;
 pub mod data;
 pub mod generics;
@@ -30,7 +33,7 @@ mod trace;
 pub mod nameres;
 
 pub mod src;
-pub mod child_from_source;
+pub mod child_by_source;
 
 #[cfg(test)]
 mod test_db;
@@ -315,6 +318,16 @@ macro_rules! impl_froms {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeParamId {
+    pub parent: GenericDefId,
+    pub local_id: LocalTypeParamId,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LocalTypeParamId(RawId);
+impl_arena_id!(LocalTypeParamId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum ContainerId {
     ModuleId(ModuleId),
     ImplId(ImplId),
@@ -512,6 +525,20 @@ impl HasModule for DefWithBodyId {
     }
 }
 
+impl HasModule for GenericDefId {
+    fn module(&self, db: &impl db::DefDatabase) -> ModuleId {
+        match self {
+            GenericDefId::FunctionId(it) => it.lookup(db).module(db),
+            GenericDefId::AdtId(it) => it.module(db),
+            GenericDefId::TraitId(it) => it.module(db),
+            GenericDefId::TypeAliasId(it) => it.lookup(db).module(db),
+            GenericDefId::ImplId(it) => it.module(db),
+            GenericDefId::EnumVariantId(it) => it.parent.module(db),
+            GenericDefId::ConstId(it) => it.lookup(db).module(db),
+        }
+    }
+}
+
 impl HasModule for StaticLoc {
     fn module(&self, _db: &impl db::DefDatabase) -> ModuleId {
         self.container
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 3b3f30eec..3ff071f9e 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -7,7 +7,7 @@ use hir_expand::{
     builtin_derive::find_builtin_derive,
     builtin_macro::find_builtin_macro,
     name::{self, AsName, Name},
-    HirFileId, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind, MacroFileKind,
+    HirFileId, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind,
 };
 use ra_cfg::CfgOptions;
 use ra_db::{CrateId, FileId};
@@ -624,7 +624,7 @@ where
         self.macro_stack_monitor.increase(macro_def_id);
 
         if !self.macro_stack_monitor.is_poison(macro_def_id) {
-            let file_id: HirFileId = macro_call_id.as_file(MacroFileKind::Items);
+            let file_id: HirFileId = macro_call_id.as_file();
             let raw_items = self.db.raw_items(file_id);
             let mod_dir = self.mod_dirs[&module_id].clone();
             ModCollector {
diff --git a/crates/ra_hir_def/src/per_ns.rs b/crates/ra_hir_def/src/per_ns.rs
index 00e866bf9..3a5105028 100644
--- a/crates/ra_hir_def/src/per_ns.rs
+++ b/crates/ra_hir_def/src/per_ns.rs
@@ -11,8 +11,6 @@ use crate::ModuleDefId;
 pub struct PerNs {
     pub types: Option<ModuleDefId>,
     pub values: Option<ModuleDefId>,
-    /// Since macros has different type, many methods simply ignore it.
-    /// We can only use special method like `get_macros` to access it.
     pub macros: Option<MacroDefId>,
 }
 
diff --git a/crates/ra_hir_def/src/resolver.rs b/crates/ra_hir_def/src/resolver.rs
index 7d4df222e..4c859e497 100644
--- a/crates/ra_hir_def/src/resolver.rs
+++ b/crates/ra_hir_def/src/resolver.rs
@@ -19,11 +19,12 @@ use crate::{
     per_ns::PerNs,
     AdtId, AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, EnumVariantId, FunctionId,
     GenericDefId, HasModule, ImplId, LocalModuleId, Lookup, ModuleDefId, ModuleId, StaticId,
-    StructId, TraitId, TypeAliasId,
+    StructId, TraitId, TypeAliasId, TypeParamId,
 };
 
 #[derive(Debug, Clone, Default)]
 pub struct Resolver {
+    // FIXME: all usages generally call `.rev`, so maybe reverse once in consturciton?
     scopes: Vec<Scope>,
 }
 
@@ -58,7 +59,7 @@ enum Scope {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum TypeNs {
     SelfType(ImplId),
-    GenericParam(u32),
+    GenericParam(TypeParamId),
     AdtId(AdtId),
     AdtSelfType(AdtId),
     // Yup, enum variants are added to the types ns, but any usage of variant as
@@ -152,10 +153,13 @@ impl Resolver {
                 Scope::ExprScope(_) => continue,
                 Scope::GenericParams { .. } | Scope::ImplBlockScope(_) if skip_to_mod => continue,
 
-                Scope::GenericParams { params, .. } => {
-                    if let Some(param) = params.find_by_name(first_name) {
+                Scope::GenericParams { params, def } => {
+                    if let Some(local_id) = params.find_by_name(first_name) {
                         let idx = if path.segments.len() == 1 { None } else { Some(1) };
-                        return Some((TypeNs::GenericParam(param.idx), idx));
+                        return Some((
+                            TypeNs::GenericParam(TypeParamId { local_id, parent: *def }),
+                            idx,
+                        ));
                     }
                 }
                 Scope::ImplBlockScope(impl_) => {
@@ -246,9 +250,9 @@ impl Resolver {
                 }
                 Scope::ExprScope(_) => continue,
 
-                Scope::GenericParams { params, .. } if n_segments > 1 => {
-                    if let Some(param) = params.find_by_name(first_name) {
-                        let ty = TypeNs::GenericParam(param.idx);
+                Scope::GenericParams { params, def } if n_segments > 1 => {
+                    if let Some(local_id) = params.find_by_name(first_name) {
+                        let ty = TypeNs::GenericParam(TypeParamId { local_id, parent: *def });
                         return Some(ResolveValueResult::Partial(ty, 1));
                     }
                 }
@@ -368,6 +372,7 @@ impl Resolver {
     ) -> impl Iterator<Item = &'a crate::generics::WherePredicate> + 'a {
         self.scopes
             .iter()
+            .rev()
             .filter_map(|scope| match scope {
                 Scope::GenericParams { params, .. } => Some(params),
                 _ => None,
@@ -376,14 +381,14 @@ impl Resolver {
     }
 
     pub fn generic_def(&self) -> Option<GenericDefId> {
-        self.scopes.iter().find_map(|scope| match scope {
+        self.scopes.iter().rev().find_map(|scope| match scope {
             Scope::GenericParams { def, .. } => Some(*def),
             _ => None,
         })
     }
 
     pub fn body_owner(&self) -> Option<DefWithBodyId> {
-        self.scopes.iter().find_map(|scope| match scope {
+        self.scopes.iter().rev().find_map(|scope| match scope {
             Scope::ExprScope(it) => Some(it.owner),
             _ => None,
         })
@@ -394,7 +399,7 @@ pub enum ScopeDef {
     PerNs(PerNs),
     ImplSelfType(ImplId),
     AdtSelfType(AdtId),
-    GenericParam(u32),
+    GenericParam(TypeParamId),
     Local(PatId),
 }
 
@@ -425,9 +430,12 @@ impl Scope {
                     });
                 }
             }
-            Scope::GenericParams { params, .. } => {
-                for param in params.params.iter() {
-                    f(param.name.clone(), ScopeDef::GenericParam(param.idx))
+            Scope::GenericParams { params, def } => {
+                for (local_id, param) in params.types.iter() {
+                    f(
+                        param.name.clone(),
+                        ScopeDef::GenericParam(TypeParamId { local_id, parent: *def }),
+                    )
                 }
             }
             Scope::ImplBlockScope(i) => {
@@ -473,7 +481,7 @@ impl Resolver {
 
     fn push_generic_params_scope(self, db: &impl DefDatabase, def: GenericDefId) -> Resolver {
         let params = db.generic_params(def);
-        if params.params.is_empty() {
+        if params.types.is_empty() {
             self
         } else {
             self.push_scope(Scope::GenericParams { def, params })
diff --git a/crates/ra_hir_expand/src/builtin_derive.rs b/crates/ra_hir_expand/src/builtin_derive.rs
index 78fa9b09a..574637602 100644
--- a/crates/ra_hir_expand/src/builtin_derive.rs
+++ b/crates/ra_hir_expand/src/builtin_derive.rs
@@ -208,7 +208,7 @@ fn partial_ord_expand(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{test_db::TestDB, AstId, MacroCallKind, MacroCallLoc, MacroFileKind};
+    use crate::{test_db::TestDB, AstId, MacroCallKind, MacroCallLoc};
     use ra_db::{fixture::WithFixture, SourceDatabase};
 
     fn expand_builtin_derive(s: &str, expander: BuiltinDeriveExpander) -> String {
@@ -229,7 +229,7 @@ mod tests {
         };
 
         let id = db.intern_macro(loc);
-        let parsed = db.parse_or_expand(id.as_file(MacroFileKind::Items)).unwrap();
+        let parsed = db.parse_or_expand(id.as_file()).unwrap();
 
         // FIXME text() for syntax nodes parsed from token tree looks weird
         // because there's no whitespace, see below
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 35f99b2bc..c7071fe85 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -2,8 +2,7 @@
 use crate::db::AstDatabase;
 use crate::{
     ast::{self, AstNode},
-    name, AstId, CrateId, HirFileId, MacroCallId, MacroDefId, MacroDefKind, MacroFileKind,
-    TextUnit,
+    name, AstId, CrateId, HirFileId, MacroCallId, MacroDefId, MacroDefKind, TextUnit,
 };
 
 use crate::quote;
@@ -49,7 +48,11 @@ register_builtin! {
     (COMPILE_ERROR_MACRO, CompileError) => compile_error_expand,
     (FILE_MACRO, File) => file_expand,
     (LINE_MACRO, Line) => line_expand,
-    (STRINGIFY_MACRO, Stringify) => stringify_expand
+    (STRINGIFY_MACRO, Stringify) => stringify_expand,
+    (FORMAT_ARGS_MACRO, FormatArgs) => format_args_expand,
+    // format_args_nl only differs in that it adds a newline in the end,
+    // so we use the same stub expansion for now
+    (FORMAT_ARGS_NL_MACRO, FormatArgsNl) => format_args_expand
 }
 
 fn to_line_number(db: &dyn AstDatabase, file: HirFileId, pos: TextUnit) -> usize {
@@ -86,7 +89,7 @@ fn line_expand(
     let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
     let arg_start = arg.text_range().start();
 
-    let file = id.as_file(MacroFileKind::Expr);
+    let file = id.as_file();
     let line_num = to_line_number(db, file, arg_start);
 
     let expanded = quote! {
@@ -154,7 +157,7 @@ fn column_expand(
     let _arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
     let col_start = macro_call.syntax().text_range().start();
 
-    let file = id.as_file(MacroFileKind::Expr);
+    let file = id.as_file();
     let col_num = to_col_number(db, file, col_start);
 
     let expanded = quote! {
@@ -200,6 +203,41 @@ fn compile_error_expand(
     Err(mbe::ExpandError::BindingError("Must be a string".into()))
 }
 
+fn format_args_expand(
+    _db: &dyn AstDatabase,
+    _id: MacroCallId,
+    tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    // We expand `format_args!("", arg1, arg2)` to
+    // `std::fmt::Arguments::new_v1(&[], &[&arg1, &arg2])`,
+    // which is still not really correct, but close enough for now
+    let mut args = Vec::new();
+    let mut current = Vec::new();
+    for tt in tt.token_trees.iter().cloned() {
+        match tt {
+            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                args.push(tt::Subtree { delimiter: tt::Delimiter::None, token_trees: current });
+                current = Vec::new();
+            }
+            _ => {
+                current.push(tt);
+            }
+        }
+    }
+    if !current.is_empty() {
+        args.push(tt::Subtree { delimiter: tt::Delimiter::None, token_trees: current });
+    }
+    if args.is_empty() {
+        return Err(mbe::ExpandError::NoMatchingRule);
+    }
+    let _format_string = args.remove(0);
+    let arg_tts = args.into_iter().flat_map(|arg| (quote! { & #arg , }).token_trees);
+    let expanded = quote! {
+        std::fmt::Arguments::new_v1(&[], &[##arg_tts])
+    };
+    Ok(expanded)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -230,7 +268,7 @@ mod tests {
         };
 
         let id = db.intern_macro(loc);
-        let parsed = db.parse_or_expand(id.as_file(MacroFileKind::Expr)).unwrap();
+        let parsed = db.parse_or_expand(id.as_file()).unwrap();
 
         parsed.text().to_string()
     }
@@ -307,4 +345,21 @@ mod tests {
 
         assert_eq!(expanded, r#"loop{"error!"}"#);
     }
+
+    #[test]
+    fn test_format_args_expand() {
+        let expanded = expand_builtin_macro(
+            r#"
+        #[rustc_builtin_macro]
+        macro_rules! format_args {
+            ($fmt:expr) => ({ /* compiler built-in */ });
+            ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+        }
+        format_args!("{} {:?}", arg1(a, b, c), arg2);
+"#,
+            BuiltinFnLikeExpander::FormatArgs,
+        );
+
+        assert_eq!(expanded, r#"std::fmt::Arguments::new_v1(&[] ,&[&arg1(a,b,c),&arg2,])"#);
+    }
 }
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index 99dabf3fb..4bdb41619 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -6,11 +6,11 @@ use mbe::MacroRules;
 use ra_db::{salsa, SourceDatabase};
 use ra_parser::FragmentKind;
 use ra_prof::profile;
-use ra_syntax::{AstNode, Parse, SyntaxNode};
+use ra_syntax::{AstNode, Parse, SyntaxKind::*, SyntaxNode};
 
 use crate::{
     ast_id_map::AstIdMap, BuiltinDeriveExpander, BuiltinFnLikeExpander, HirFileId, HirFileIdRepr,
-    MacroCallId, MacroCallLoc, MacroDefId, MacroDefKind, MacroFile, MacroFileKind,
+    MacroCallId, MacroCallLoc, MacroDefId, MacroDefKind, MacroFile,
 };
 
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -45,8 +45,8 @@ impl TokenExpander {
     pub fn map_id_up(&self, id: tt::TokenId) -> (tt::TokenId, mbe::Origin) {
         match self {
             TokenExpander::MacroRules(it) => it.map_id_up(id),
-            TokenExpander::Builtin(..) => (id, mbe::Origin::Def),
-            TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Def),
+            TokenExpander::Builtin(..) => (id, mbe::Origin::Call),
+            TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Call),
         }
     }
 }
@@ -155,11 +155,42 @@ pub(crate) fn parse_macro(
         })
         .ok()?;
 
-    let fragment_kind = match macro_file.macro_file_kind {
-        MacroFileKind::Items => FragmentKind::Items,
-        MacroFileKind::Expr => FragmentKind::Expr,
-        MacroFileKind::Statements => FragmentKind::Statements,
-    };
+    let fragment_kind = to_fragment_kind(db, macro_call_id);
+
     let (parse, rev_token_map) = mbe::token_tree_to_syntax_node(&tt, fragment_kind).ok()?;
     Some((parse, Arc::new(rev_token_map)))
 }
+
+/// Given a `MacroCallId`, return what `FragmentKind` it belongs to.
+/// FIXME: Not completed
+fn to_fragment_kind(db: &dyn AstDatabase, macro_call_id: MacroCallId) -> FragmentKind {
+    let syn = db.lookup_intern_macro(macro_call_id).kind.node(db).value;
+
+    let parent = match syn.parent() {
+        Some(it) => it,
+        None => {
+            // FIXME:
+            // If it is root, which means the parent HirFile
+            // MacroKindFile must be non-items
+            // return expr now.
+            return FragmentKind::Expr;
+        }
+    };
+
+    match parent.kind() {
+        MACRO_ITEMS | SOURCE_FILE => FragmentKind::Items,
+        LET_STMT => {
+            // FIXME: Handle Pattern
+            FragmentKind::Expr
+        }
+        EXPR_STMT => FragmentKind::Statements,
+        BLOCK => FragmentKind::Statements,
+        ARG_LIST => FragmentKind::Expr,
+        TRY_EXPR => FragmentKind::Expr,
+        TUPLE_EXPR => FragmentKind::Expr,
+        _ => {
+            // Unknown , Just guess it is `Items`
+            FragmentKind::Items
+        }
+    }
+}
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 59c69b91b..94e1e466a 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -76,6 +76,17 @@ impl HirFileId {
         }
     }
 
+    /// If this is a macro call, returns the syntax node of the call.
+    pub fn call_node(self, db: &dyn db::AstDatabase) -> Option<InFile<SyntaxNode>> {
+        match self.0 {
+            HirFileIdRepr::FileId(_) => None,
+            HirFileIdRepr::MacroFile(macro_file) => {
+                let loc = db.lookup_intern_macro(macro_file.macro_call_id);
+                Some(loc.kind.node(db))
+            }
+        }
+    }
+
     /// Return expansion information if it is a macro-expansion file
     pub fn expansion_info(self, db: &dyn db::AstDatabase) -> Option<ExpansionInfo> {
         match self.0 {
@@ -106,14 +117,6 @@ impl HirFileId {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct MacroFile {
     macro_call_id: MacroCallId,
-    macro_file_kind: MacroFileKind,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum MacroFileKind {
-    Items,
-    Expr,
-    Statements,
 }
 
 /// `MacroCallId` identifies a particular macro invocation, like
@@ -176,6 +179,13 @@ impl MacroCallKind {
         }
     }
 
+    pub fn node(&self, db: &dyn db::AstDatabase) -> InFile<SyntaxNode> {
+        match self {
+            MacroCallKind::FnLike(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
+            MacroCallKind::Attr(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
+        }
+    }
+
     pub fn arg(&self, db: &dyn db::AstDatabase) -> Option<SyntaxNode> {
         match self {
             MacroCallKind::FnLike(ast_id) => {
@@ -187,9 +197,8 @@ impl MacroCallKind {
 }
 
 impl MacroCallId {
-    pub fn as_file(self, kind: MacroFileKind) -> HirFileId {
-        let macro_file = MacroFile { macro_call_id: self, macro_file_kind: kind };
-        macro_file.into()
+    pub fn as_file(self) -> HirFileId {
+        MacroFile { macro_call_id: self }.into()
     }
 }
 
@@ -283,3 +292,24 @@ impl<T> InFile<T> {
         db.parse_or_expand(self.file_id).expect("source created from invalid file")
     }
 }
+
+impl<T: Clone> InFile<&T> {
+    pub fn cloned(&self) -> InFile<T> {
+        self.with_value(self.value.clone())
+    }
+}
+
+impl InFile<SyntaxNode> {
+    pub fn ancestors_with_macros<'a>(
+        self,
+        db: &'a impl crate::db::AstDatabase,
+    ) -> impl Iterator<Item = InFile<SyntaxNode>> + 'a {
+        std::iter::successors(Some(self), move |node| match node.value.parent() {
+            Some(parent) => Some(node.with_value(parent)),
+            None => {
+                let parent_node = node.file_id.call_node(db)?;
+                Some(parent_node)
+            }
+        })
+    }
+}
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index c5a191160..4f2f702c0 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -38,8 +38,8 @@ impl Name {
     }
 
     /// Shortcut to create inline plain text name
-    const fn new_inline_ascii(len: usize, text: &[u8]) -> Name {
-        Name::new_text(SmolStr::new_inline_from_ascii(len, text))
+    const fn new_inline_ascii(text: &[u8]) -> Name {
+        Name::new_text(SmolStr::new_inline_from_ascii(text.len(), text))
     }
 
     /// Resolve a name from the text of token.
@@ -105,68 +105,70 @@ impl AsName for ra_db::Dependency {
 }
 
 // Primitives
-pub const ISIZE: Name = Name::new_inline_ascii(5, b"isize");
-pub const I8: Name = Name::new_inline_ascii(2, b"i8");
-pub const I16: Name = Name::new_inline_ascii(3, b"i16");
-pub const I32: Name = Name::new_inline_ascii(3, b"i32");
-pub const I64: Name = Name::new_inline_ascii(3, b"i64");
-pub const I128: Name = Name::new_inline_ascii(4, b"i128");
-pub const USIZE: Name = Name::new_inline_ascii(5, b"usize");
-pub const U8: Name = Name::new_inline_ascii(2, b"u8");
-pub const U16: Name = Name::new_inline_ascii(3, b"u16");
-pub const U32: Name = Name::new_inline_ascii(3, b"u32");
-pub const U64: Name = Name::new_inline_ascii(3, b"u64");
-pub const U128: Name = Name::new_inline_ascii(4, b"u128");
-pub const F32: Name = Name::new_inline_ascii(3, b"f32");
-pub const F64: Name = Name::new_inline_ascii(3, b"f64");
-pub const BOOL: Name = Name::new_inline_ascii(4, b"bool");
-pub const CHAR: Name = Name::new_inline_ascii(4, b"char");
-pub const STR: Name = Name::new_inline_ascii(3, b"str");
+pub const ISIZE: Name = Name::new_inline_ascii(b"isize");
+pub const I8: Name = Name::new_inline_ascii(b"i8");
+pub const I16: Name = Name::new_inline_ascii(b"i16");
+pub const I32: Name = Name::new_inline_ascii(b"i32");
+pub const I64: Name = Name::new_inline_ascii(b"i64");
+pub const I128: Name = Name::new_inline_ascii(b"i128");
+pub const USIZE: Name = Name::new_inline_ascii(b"usize");
+pub const U8: Name = Name::new_inline_ascii(b"u8");
+pub const U16: Name = Name::new_inline_ascii(b"u16");
+pub const U32: Name = Name::new_inline_ascii(b"u32");
+pub const U64: Name = Name::new_inline_ascii(b"u64");
+pub const U128: Name = Name::new_inline_ascii(b"u128");
+pub const F32: Name = Name::new_inline_ascii(b"f32");
+pub const F64: Name = Name::new_inline_ascii(b"f64");
+pub const BOOL: Name = Name::new_inline_ascii(b"bool");
+pub const CHAR: Name = Name::new_inline_ascii(b"char");
+pub const STR: Name = Name::new_inline_ascii(b"str");
 
 // Special names
-pub const SELF_PARAM: Name = Name::new_inline_ascii(4, b"self");
-pub const SELF_TYPE: Name = Name::new_inline_ascii(4, b"Self");
-pub const MACRO_RULES: Name = Name::new_inline_ascii(11, b"macro_rules");
+pub const SELF_PARAM: Name = Name::new_inline_ascii(b"self");
+pub const SELF_TYPE: Name = Name::new_inline_ascii(b"Self");
+pub const MACRO_RULES: Name = Name::new_inline_ascii(b"macro_rules");
 
 // Components of known path (value or mod name)
-pub const STD: Name = Name::new_inline_ascii(3, b"std");
-pub const ITER: Name = Name::new_inline_ascii(4, b"iter");
-pub const OPS: Name = Name::new_inline_ascii(3, b"ops");
-pub const FUTURE: Name = Name::new_inline_ascii(6, b"future");
-pub const RESULT: Name = Name::new_inline_ascii(6, b"result");
-pub const BOXED: Name = Name::new_inline_ascii(5, b"boxed");
+pub const STD: Name = Name::new_inline_ascii(b"std");
+pub const ITER: Name = Name::new_inline_ascii(b"iter");
+pub const OPS: Name = Name::new_inline_ascii(b"ops");
+pub const FUTURE: Name = Name::new_inline_ascii(b"future");
+pub const RESULT: Name = Name::new_inline_ascii(b"result");
+pub const BOXED: Name = Name::new_inline_ascii(b"boxed");
 
 // Components of known path (type name)
-pub const INTO_ITERATOR_TYPE: Name = Name::new_inline_ascii(12, b"IntoIterator");
-pub const ITEM_TYPE: Name = Name::new_inline_ascii(4, b"Item");
-pub const TRY_TYPE: Name = Name::new_inline_ascii(3, b"Try");
-pub const OK_TYPE: Name = Name::new_inline_ascii(2, b"Ok");
-pub const FUTURE_TYPE: Name = Name::new_inline_ascii(6, b"Future");
-pub const RESULT_TYPE: Name = Name::new_inline_ascii(6, b"Result");
-pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(6, b"Output");
-pub const TARGET_TYPE: Name = Name::new_inline_ascii(6, b"Target");
-pub const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");
-pub const RANGE_FROM_TYPE: Name = Name::new_inline_ascii(9, b"RangeFrom");
-pub const RANGE_FULL_TYPE: Name = Name::new_inline_ascii(9, b"RangeFull");
-pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(14, b"RangeInclusive");
-pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(16, b"RangeToInclusive");
-pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(7, b"RangeTo");
-pub const RANGE_TYPE: Name = Name::new_inline_ascii(5, b"Range");
+pub const INTO_ITERATOR_TYPE: Name = Name::new_inline_ascii(b"IntoIterator");
+pub const ITEM_TYPE: Name = Name::new_inline_ascii(b"Item");
+pub const TRY_TYPE: Name = Name::new_inline_ascii(b"Try");
+pub const OK_TYPE: Name = Name::new_inline_ascii(b"Ok");
+pub const FUTURE_TYPE: Name = Name::new_inline_ascii(b"Future");
+pub const RESULT_TYPE: Name = Name::new_inline_ascii(b"Result");
+pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(b"Output");
+pub const TARGET_TYPE: Name = Name::new_inline_ascii(b"Target");
+pub const BOX_TYPE: Name = Name::new_inline_ascii(b"Box");
+pub const RANGE_FROM_TYPE: Name = Name::new_inline_ascii(b"RangeFrom");
+pub const RANGE_FULL_TYPE: Name = Name::new_inline_ascii(b"RangeFull");
+pub const RANGE_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeInclusive");
+pub const RANGE_TO_INCLUSIVE_TYPE: Name = Name::new_inline_ascii(b"RangeToInclusive");
+pub const RANGE_TO_TYPE: Name = Name::new_inline_ascii(b"RangeTo");
+pub const RANGE_TYPE: Name = Name::new_inline_ascii(b"Range");
 
 // Builtin Macros
-pub const FILE_MACRO: Name = Name::new_inline_ascii(4, b"file");
-pub const COLUMN_MACRO: Name = Name::new_inline_ascii(6, b"column");
-pub const COMPILE_ERROR_MACRO: Name = Name::new_inline_ascii(13, b"compile_error");
-pub const LINE_MACRO: Name = Name::new_inline_ascii(4, b"line");
-pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(9, b"stringify");
+pub const FILE_MACRO: Name = Name::new_inline_ascii(b"file");
+pub const COLUMN_MACRO: Name = Name::new_inline_ascii(b"column");
+pub const COMPILE_ERROR_MACRO: Name = Name::new_inline_ascii(b"compile_error");
+pub const LINE_MACRO: Name = Name::new_inline_ascii(b"line");
+pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(b"stringify");
+pub const FORMAT_ARGS_MACRO: Name = Name::new_inline_ascii(b"format_args");
+pub const FORMAT_ARGS_NL_MACRO: Name = Name::new_inline_ascii(b"format_args_nl");
 
 // Builtin derives
-pub const COPY_TRAIT: Name = Name::new_inline_ascii(4, b"Copy");
-pub const CLONE_TRAIT: Name = Name::new_inline_ascii(5, b"Clone");
-pub const DEFAULT_TRAIT: Name = Name::new_inline_ascii(7, b"Default");
-pub const DEBUG_TRAIT: Name = Name::new_inline_ascii(5, b"Debug");
-pub const HASH_TRAIT: Name = Name::new_inline_ascii(4, b"Hash");
-pub const ORD_TRAIT: Name = Name::new_inline_ascii(3, b"Ord");
-pub const PARTIAL_ORD_TRAIT: Name = Name::new_inline_ascii(10, b"PartialOrd");
-pub const EQ_TRAIT: Name = Name::new_inline_ascii(2, b"Eq");
-pub const PARTIAL_EQ_TRAIT: Name = Name::new_inline_ascii(9, b"PartialEq");
+pub const COPY_TRAIT: Name = Name::new_inline_ascii(b"Copy");
+pub const CLONE_TRAIT: Name = Name::new_inline_ascii(b"Clone");
+pub const DEFAULT_TRAIT: Name = Name::new_inline_ascii(b"Default");
+pub const DEBUG_TRAIT: Name = Name::new_inline_ascii(b"Debug");
+pub const HASH_TRAIT: Name = Name::new_inline_ascii(b"Hash");
+pub const ORD_TRAIT: Name = Name::new_inline_ascii(b"Ord");
+pub const PARTIAL_ORD_TRAIT: Name = Name::new_inline_ascii(b"PartialOrd");
+pub const EQ_TRAIT: Name = Name::new_inline_ascii(b"Eq");
+pub const PARTIAL_EQ_TRAIT: Name = Name::new_inline_ascii(b"PartialEq");
diff --git a/crates/ra_hir_ty/src/autoderef.rs b/crates/ra_hir_ty/src/autoderef.rs
index 9d1d4e48c..d557962b4 100644
--- a/crates/ra_hir_ty/src/autoderef.rs
+++ b/crates/ra_hir_ty/src/autoderef.rs
@@ -10,10 +10,10 @@ use hir_expand::name;
 use log::{info, warn};
 use ra_db::CrateId;
 
-use crate::db::HirDatabase;
-
-use super::{
+use crate::{
+    db::HirDatabase,
     traits::{InEnvironment, Solution},
+    utils::generics,
     Canonical, Substs, Ty, TypeWalk,
 };
 
@@ -54,8 +54,8 @@ fn deref_by_trait(
     };
     let target = db.trait_data(deref_trait).associated_type_by_name(&name::TARGET_TYPE)?;
 
-    let generic_params = db.generic_params(target.into());
-    if generic_params.count_params_including_parent() != 1 {
+    let generic_params = generics(db, target.into());
+    if generic_params.len() != 1 {
         // the Target type + Deref trait should only have one generic parameter,
         // namely Deref's Self type
         return None;
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index b8df27706..2c296987c 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -6,7 +6,6 @@ use std::sync::Arc;
 use hir_def::{
     builtin_type::Signedness,
     expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
-    generics::GenericParams,
     path::{GenericArg, GenericArgs},
     resolver::resolver_for_expr,
     AdtId, ContainerId, Lookup, StructFieldId,
@@ -15,7 +14,11 @@ use hir_expand::name::{self, Name};
 use ra_syntax::ast::RangeOp;
 
 use crate::{
-    autoderef, db::HirDatabase, method_resolution, op, traits::InEnvironment, utils::variant_data,
+    autoderef,
+    db::HirDatabase,
+    method_resolution, op,
+    traits::InEnvironment,
+    utils::{generics, variant_data, Generics},
     CallableDef, InferTy, IntTy, Mutability, Obligation, ProjectionPredicate, ProjectionTy, Substs,
     TraitRef, Ty, TypeCtor, TypeWalk, Uncertain,
 };
@@ -596,7 +599,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Some((ty, func)) => {
                 let ty = canonicalized_receiver.decanonicalize_ty(ty);
                 self.write_method_resolution(tgt_expr, func);
-                (ty, self.db.value_ty(func.into()), Some(self.db.generic_params(func.into())))
+                (ty, self.db.value_ty(func.into()), Some(generics(self.db, func.into())))
             }
             None => (receiver_ty, Ty::Unknown, None),
         };
@@ -653,16 +656,16 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
     fn substs_for_method_call(
         &mut self,
-        def_generics: Option<Arc<GenericParams>>,
+        def_generics: Option<Generics>,
         generic_args: Option<&GenericArgs>,
         receiver_ty: &Ty,
     ) -> Substs {
-        let (parent_param_count, param_count) =
-            def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
-        let mut substs = Vec::with_capacity(parent_param_count + param_count);
+        let (total_len, _parent_len, child_len) =
+            def_generics.as_ref().map_or((0, 0, 0), |g| g.len_split());
+        let mut substs = Vec::with_capacity(total_len);
         // Parent arguments are unknown, except for the receiver type
-        if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
-            for param in &parent_generics.params {
+        if let Some(parent_generics) = def_generics.as_ref().map(|p| p.iter_parent()) {
+            for (_id, param) in parent_generics {
                 if param.name == name::SELF_TYPE {
                     substs.push(receiver_ty.clone());
                 } else {
@@ -673,7 +676,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         // handle provided type arguments
         if let Some(generic_args) = generic_args {
             // if args are provided, it should be all of them, but we can't rely on that
-            for arg in generic_args.args.iter().take(param_count) {
+            for arg in generic_args.args.iter().take(child_len) {
                 match arg {
                     GenericArg::Type(type_ref) => {
                         let ty = self.make_ty(type_ref);
@@ -683,10 +686,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             }
         };
         let supplied_params = substs.len();
-        for _ in supplied_params..parent_param_count + param_count {
+        for _ in supplied_params..total_len {
             substs.push(Ty::Unknown);
         }
-        assert_eq!(substs.len(), parent_param_count + param_count);
+        assert_eq!(substs.len(), total_len);
         Substs(substs.into())
     }
 
@@ -705,11 +708,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     CallableDef::FunctionId(f) => {
                         if let ContainerId::TraitId(trait_) = f.lookup(self.db).container {
                             // construct a TraitDef
-                            let substs = a_ty.parameters.prefix(
-                                self.db
-                                    .generic_params(trait_.into())
-                                    .count_params_including_parent(),
-                            );
+                            let substs =
+                                a_ty.parameters.prefix(generics(self.db, trait_.into()).len());
                             self.obligations.push(Obligation::Trait(TraitRef {
                                 trait_: trait_.into(),
                                 substs,
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 3c1f738df..3ad913e55 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -44,8 +44,8 @@ use std::sync::Arc;
 use std::{fmt, iter, mem};
 
 use hir_def::{
-    expr::ExprId, generics::GenericParams, type_ref::Mutability, AdtId, ContainerId, DefWithBodyId,
-    GenericDefId, HasModule, Lookup, TraitId, TypeAliasId,
+    expr::ExprId, type_ref::Mutability, AdtId, ContainerId, DefWithBodyId, GenericDefId, HasModule,
+    Lookup, TraitId, TypeAliasId,
 };
 use hir_expand::name::Name;
 use ra_db::{impl_intern_key, salsa, CrateId};
@@ -53,7 +53,7 @@ use ra_db::{impl_intern_key, salsa, CrateId};
 use crate::{
     db::HirDatabase,
     primitive::{FloatTy, IntTy, Uncertain},
-    utils::make_mut_slice,
+    utils::{generics, make_mut_slice, Generics},
 };
 use display::{HirDisplay, HirFormatter};
 
@@ -166,16 +166,16 @@ impl TypeCtor {
             | TypeCtor::Closure { .. } // 1 param representing the signature of the closure
             => 1,
             TypeCtor::Adt(adt) => {
-                let generic_params = db.generic_params(AdtId::from(adt).into());
-                generic_params.count_params_including_parent()
+                let generic_params = generics(db, AdtId::from(adt).into());
+                generic_params.len()
             }
             TypeCtor::FnDef(callable) => {
-                let generic_params = db.generic_params(callable.into());
-                generic_params.count_params_including_parent()
+                let generic_params = generics(db, callable.into());
+                generic_params.len()
             }
             TypeCtor::AssociatedType(type_alias) => {
-                let generic_params = db.generic_params(type_alias.into());
-                generic_params.count_params_including_parent()
+                let generic_params = generics(db, type_alias.into());
+                generic_params.len()
             }
             TypeCtor::FnPtr { num_args } => num_args as usize + 1,
             TypeCtor::Tuple { cardinality } => cardinality as usize,
@@ -364,36 +364,26 @@ impl Substs {
     }
 
     /// Return Substs that replace each parameter by itself (i.e. `Ty::Param`).
-    pub fn identity(generic_params: &GenericParams) -> Substs {
+    pub(crate) fn identity(generic_params: &Generics) -> Substs {
         Substs(
-            generic_params
-                .params_including_parent()
-                .into_iter()
-                .map(|p| Ty::Param { idx: p.idx, name: p.name.clone() })
-                .collect(),
+            generic_params.iter().map(|(idx, p)| Ty::Param { idx, name: p.name.clone() }).collect(),
         )
     }
 
     /// Return Substs that replace each parameter by a bound variable.
-    pub fn bound_vars(generic_params: &GenericParams) -> Substs {
-        Substs(
-            generic_params
-                .params_including_parent()
-                .into_iter()
-                .map(|p| Ty::Bound(p.idx))
-                .collect(),
-        )
+    pub(crate) fn bound_vars(generic_params: &Generics) -> Substs {
+        Substs(generic_params.iter().map(|(idx, _p)| Ty::Bound(idx)).collect())
     }
 
     pub fn build_for_def(db: &impl HirDatabase, def: impl Into<GenericDefId>) -> SubstsBuilder {
         let def = def.into();
-        let params = db.generic_params(def);
-        let param_count = params.count_params_including_parent();
+        let params = generics(db, def);
+        let param_count = params.len();
         Substs::builder(param_count)
     }
 
-    pub fn build_for_generics(generic_params: &GenericParams) -> SubstsBuilder {
-        Substs::builder(generic_params.count_params_including_parent())
+    pub(crate) fn build_for_generics(generic_params: &Generics) -> SubstsBuilder {
+        Substs::builder(generic_params.len())
     }
 
     pub fn build_for_type_ctor(db: &impl HirDatabase, type_ctor: TypeCtor) -> SubstsBuilder {
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index 32569ac66..eab91229e 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -24,7 +24,7 @@ use crate::{
     db::HirDatabase,
     primitive::{FloatTy, IntTy},
     utils::{
-        all_super_traits, associated_type_by_name_including_super_traits, make_mut_slice,
+        all_super_traits, associated_type_by_name_including_super_traits, generics, make_mut_slice,
         variant_data,
     },
     FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitEnvironment, TraitRef,
@@ -111,7 +111,9 @@ impl Ty {
             Some((it, None)) => it,
             _ => return None,
         };
-        if let TypeNs::GenericParam(idx) = resolution {
+        if let TypeNs::GenericParam(param_id) = resolution {
+            let generics = generics(db, resolver.generic_def().expect("generics in scope"));
+            let idx = generics.param_idx(param_id);
             Some(idx)
         } else {
             None
@@ -174,9 +176,11 @@ impl Ty {
                     Ty::Dyn(Arc::new([GenericPredicate::Implemented(trait_ref)]))
                 };
             }
-            TypeNs::GenericParam(idx) => {
+            TypeNs::GenericParam(param_id) => {
+                let generics = generics(db, resolver.generic_def().expect("generics in scope"));
+                let idx = generics.param_idx(param_id);
                 // FIXME: maybe return name in resolution?
-                let name = resolved_segment.name.clone();
+                let name = generics.param_name(param_id);
                 Ty::Param { idx, name }
             }
             TypeNs::SelfType(impl_id) => db.impl_self_ty(impl_id).clone(),
@@ -315,11 +319,10 @@ pub(super) fn substs_from_path_segment(
     add_self_param: bool,
 ) -> Substs {
     let mut substs = Vec::new();
-    let def_generics = def_generic.map(|def| db.generic_params(def.into()));
+    let def_generics = def_generic.map(|def| generics(db, def.into()));
 
-    let (parent_param_count, param_count) =
-        def_generics.map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
-    substs.extend(iter::repeat(Ty::Unknown).take(parent_param_count));
+    let (total_len, parent_len, child_len) = def_generics.map_or((0, 0, 0), |g| g.len_split());
+    substs.extend(iter::repeat(Ty::Unknown).take(parent_len));
     if add_self_param {
         // FIXME this add_self_param argument is kind of a hack: Traits have the
         // Self type as an implicit first type parameter, but it can't be
@@ -330,8 +333,8 @@ pub(super) fn substs_from_path_segment(
     if let Some(generic_args) = &segment.args_and_bindings {
         // if args are provided, it should be all of them, but we can't rely on that
         let self_param_correction = if add_self_param { 1 } else { 0 };
-        let param_count = param_count - self_param_correction;
-        for arg in generic_args.args.iter().take(param_count) {
+        let child_len = child_len + self_param_correction;
+        for arg in generic_args.args.iter().take(child_len) {
             match arg {
                 GenericArg::Type(type_ref) => {
                     let ty = Ty::from_hir(db, resolver, type_ref);
@@ -342,10 +345,10 @@ pub(super) fn substs_from_path_segment(
     }
     // add placeholders for args that were not provided
     let supplied_params = substs.len();
-    for _ in supplied_params..parent_param_count + param_count {
+    for _ in supplied_params..total_len {
         substs.push(Ty::Unknown);
     }
-    assert_eq!(substs.len(), parent_param_count + param_count);
+    assert_eq!(substs.len(), total_len);
 
     // handle defaults
     if let Some(def_generic) = def_generic {
@@ -567,12 +570,11 @@ pub(crate) fn generic_predicates_query(
 /// Resolve the default type params from generics
 pub(crate) fn generic_defaults_query(db: &impl HirDatabase, def: GenericDefId) -> Substs {
     let resolver = def.resolver(db);
-    let generic_params = db.generic_params(def.into());
+    let generic_params = generics(db, def.into());
 
     let defaults = generic_params
-        .params_including_parent()
-        .into_iter()
-        .map(|p| p.default.as_ref().map_or(Ty::Unknown, |t| Ty::from_hir(db, &resolver, t)))
+        .iter()
+        .map(|(_idx, p)| p.default.as_ref().map_or(Ty::Unknown, |t| Ty::from_hir(db, &resolver, t)))
         .collect();
 
     Substs(defaults)
@@ -589,7 +591,7 @@ fn fn_sig_for_fn(db: &impl HirDatabase, def: FunctionId) -> FnSig {
 /// Build the declared type of a function. This should not need to look at the
 /// function body.
 fn type_for_fn(db: &impl HirDatabase, def: FunctionId) -> Ty {
-    let generics = db.generic_params(def.into());
+    let generics = generics(db, def.into());
     let substs = Substs::identity(&generics);
     Ty::apply(TypeCtor::FnDef(def.into()), substs)
 }
@@ -639,7 +641,7 @@ fn type_for_struct_constructor(db: &impl HirDatabase, def: StructId) -> Ty {
     if struct_data.variant_data.is_unit() {
         return type_for_adt(db, def.into()); // Unit struct
     }
-    let generics = db.generic_params(def.into());
+    let generics = generics(db, def.into());
     let substs = Substs::identity(&generics);
     Ty::apply(TypeCtor::FnDef(def.into()), substs)
 }
@@ -653,7 +655,7 @@ fn fn_sig_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariantId
         .iter()
         .map(|(_, field)| Ty::from_hir(db, &resolver, &field.type_ref))
         .collect::<Vec<_>>();
-    let generics = db.generic_params(def.parent.into());
+    let generics = generics(db, def.parent.into());
     let substs = Substs::identity(&generics);
     let ret = type_for_adt(db, def.parent.into()).subst(&substs);
     FnSig::from_params_and_return(params, ret)
@@ -666,18 +668,18 @@ fn type_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariantId)
     if var_data.is_unit() {
         return type_for_adt(db, def.parent.into()); // Unit variant
     }
-    let generics = db.generic_params(def.parent.into());
+    let generics = generics(db, def.parent.into());
     let substs = Substs::identity(&generics);
     Ty::apply(TypeCtor::FnDef(EnumVariantId::from(def).into()), substs)
 }
 
 fn type_for_adt(db: &impl HirDatabase, adt: AdtId) -> Ty {
-    let generics = db.generic_params(adt.into());
+    let generics = generics(db, adt.into());
     Ty::apply(TypeCtor::Adt(adt), Substs::identity(&generics))
 }
 
 fn type_for_type_alias(db: &impl HirDatabase, t: TypeAliasId) -> Ty {
-    let generics = db.generic_params(t.into());
+    let generics = generics(db, t.into());
     let resolver = t.resolver(db);
     let type_ref = &db.type_alias_data(t).type_ref;
     let substs = Substs::identity(&generics);
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index f1b67555f..d724ee122 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -11,8 +11,8 @@ use std::fmt::Write;
 use std::sync::Arc;
 
 use hir_def::{
-    body::BodySourceMap, child_from_source::ChildFromSource, db::DefDatabase, nameres::CrateDefMap,
-    AssocItemId, DefWithBodyId, LocalModuleId, Lookup, ModuleDefId,
+    body::BodySourceMap, child_by_source::ChildBySource, db::DefDatabase, keys,
+    nameres::CrateDefMap, AssocItemId, DefWithBodyId, LocalModuleId, Lookup, ModuleDefId,
 };
 use hir_expand::InFile;
 use insta::assert_snapshot;
@@ -33,7 +33,9 @@ fn type_at_pos(db: &TestDB, pos: FilePosition) -> String {
     let expr = algo::find_node_at_offset::<ast::Expr>(file.syntax(), pos.offset).unwrap();
     let fn_def = expr.syntax().ancestors().find_map(ast::FnDef::cast).unwrap();
     let module = db.module_for_file(pos.file_id);
-    let func = module.child_from_source(db, InFile::new(pos.file_id.into(), fn_def)).unwrap();
+    let func = *module.child_by_source(db)[keys::FUNCTION]
+        .get(&InFile::new(pos.file_id.into(), fn_def))
+        .unwrap();
 
     let (_body, source_map) = db.body_with_source_map(func.into());
     if let Some(expr_id) = source_map.node_expr(InFile::new(pos.file_id.into(), &expr)) {
diff --git a/crates/ra_hir_ty/src/traits/chalk.rs b/crates/ra_hir_ty/src/traits/chalk.rs
index e3f02fa15..1e7ff93d5 100644
--- a/crates/ra_hir_ty/src/traits/chalk.rs
+++ b/crates/ra_hir_ty/src/traits/chalk.rs
@@ -19,8 +19,8 @@ use ra_db::{
 
 use super::{builtin, AssocTyValue, Canonical, ChalkContext, Impl, Obligation};
 use crate::{
-    db::HirDatabase, display::HirDisplay, ApplicationTy, GenericPredicate, ProjectionTy, Substs,
-    TraitRef, Ty, TypeCtor, TypeWalk,
+    db::HirDatabase, display::HirDisplay, utils::generics, ApplicationTy, GenericPredicate,
+    ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
 };
 
 /// This represents a trait whose name we could not resolve.
@@ -547,7 +547,7 @@ pub(crate) fn associated_ty_data_query(
         ContainerId::TraitId(t) => t,
         _ => panic!("associated type not in trait"),
     };
-    let generic_params = db.generic_params(type_alias.into());
+    let generic_params = generics(db, type_alias.into());
     let bound_data = chalk_rust_ir::AssociatedTyDatumBound {
         // FIXME add bounds and where clauses
         bounds: vec![],
@@ -557,7 +557,7 @@ pub(crate) fn associated_ty_data_query(
         trait_id: trait_.to_chalk(db),
         id,
         name: lalrpop_intern::intern(&db.type_alias_data(type_alias).name.to_string()),
-        binders: make_binders(bound_data, generic_params.count_params_including_parent()),
+        binders: make_binders(bound_data, generic_params.len()),
     };
     Arc::new(datum)
 }
@@ -589,7 +589,7 @@ pub(crate) fn trait_datum_query(
     let trait_: TraitId = from_chalk(db, trait_id);
     let trait_data = db.trait_data(trait_);
     debug!("trait {:?} = {:?}", trait_id, trait_data.name);
-    let generic_params = db.generic_params(trait_.into());
+    let generic_params = generics(db, trait_.into());
     let bound_vars = Substs::bound_vars(&generic_params);
     let flags = chalk_rust_ir::TraitFlags {
         auto: trait_data.auto,
@@ -626,7 +626,7 @@ pub(crate) fn struct_datum_query(
     let where_clauses = type_ctor
         .as_generic_def()
         .map(|generic_def| {
-            let generic_params = db.generic_params(generic_def.into());
+            let generic_params = generics(db, generic_def.into());
             let bound_vars = Substs::bound_vars(&generic_params);
             convert_where_clauses(db, generic_def, &bound_vars)
         })
@@ -669,7 +669,7 @@ fn impl_block_datum(
     let trait_ref = db.impl_trait(impl_id)?;
     let impl_data = db.impl_data(impl_id);
 
-    let generic_params = db.generic_params(impl_id.into());
+    let generic_params = generics(db, impl_id.into());
     let bound_vars = Substs::bound_vars(&generic_params);
     let trait_ref = trait_ref.subst(&bound_vars);
     let trait_ = trait_ref.trait_;
@@ -767,7 +767,7 @@ fn type_alias_associated_ty_value(
         .trait_data(trait_ref.trait_)
         .associated_type_by_name(&type_alias_data.name)
         .expect("assoc ty value should not exist"); // validated when building the impl data as well
-    let generic_params = db.generic_params(impl_id.into());
+    let generic_params = generics(db, impl_id.into());
     let bound_vars = Substs::bound_vars(&generic_params);
     let ty = db.ty(type_alias.into()).subst(&bound_vars);
     let value_bound = chalk_rust_ir::AssociatedTyValueBound { ty: ty.to_chalk(db) };
diff --git a/crates/ra_hir_ty/src/utils.rs b/crates/ra_hir_ty/src/utils.rs
index e4ba890ef..aeb211a91 100644
--- a/crates/ra_hir_ty/src/utils.rs
+++ b/crates/ra_hir_ty/src/utils.rs
@@ -5,9 +5,10 @@ use std::sync::Arc;
 use hir_def::{
     adt::VariantData,
     db::DefDatabase,
+    generics::{GenericParams, TypeParamData},
     resolver::{HasResolver, TypeNs},
     type_ref::TypeRef,
-    TraitId, TypeAliasId, VariantId,
+    ContainerId, GenericDefId, Lookup, TraitId, TypeAliasId, TypeParamId, VariantId,
 };
 use hir_expand::name::{self, Name};
 
@@ -82,3 +83,81 @@ pub(crate) fn make_mut_slice<T: Clone>(a: &mut Arc<[T]>) -> &mut [T] {
     }
     Arc::get_mut(a).unwrap()
 }
+
+pub(crate) fn generics(db: &impl DefDatabase, def: GenericDefId) -> Generics {
+    let parent_generics = parent_generic_def(db, def).map(|def| Box::new(generics(db, def)));
+    Generics { def, params: db.generic_params(def), parent_generics }
+}
+
+pub(crate) struct Generics {
+    def: GenericDefId,
+    pub(crate) params: Arc<GenericParams>,
+    parent_generics: Option<Box<Generics>>,
+}
+
+impl Generics {
+    pub(crate) fn iter<'a>(&'a self) -> impl Iterator<Item = (u32, &'a TypeParamData)> + 'a {
+        self.parent_generics
+            .as_ref()
+            .into_iter()
+            .flat_map(|it| it.params.types.iter())
+            .chain(self.params.types.iter())
+            .enumerate()
+            .map(|(i, (_local_id, p))| (i as u32, p))
+    }
+
+    pub(crate) fn iter_parent<'a>(&'a self) -> impl Iterator<Item = (u32, &'a TypeParamData)> + 'a {
+        self.parent_generics
+            .as_ref()
+            .into_iter()
+            .flat_map(|it| it.params.types.iter())
+            .enumerate()
+            .map(|(i, (_local_id, p))| (i as u32, p))
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.len_split().0
+    }
+    /// (total, parents, child)
+    pub(crate) fn len_split(&self) -> (usize, usize, usize) {
+        let parent = self.parent_generics.as_ref().map_or(0, |p| p.len());
+        let child = self.params.types.len();
+        (parent + child, parent, child)
+    }
+    pub(crate) fn param_idx(&self, param: TypeParamId) -> u32 {
+        self.find_param(param).0
+    }
+    pub(crate) fn param_name(&self, param: TypeParamId) -> Name {
+        self.find_param(param).1.name.clone()
+    }
+    fn find_param(&self, param: TypeParamId) -> (u32, &TypeParamData) {
+        if param.parent == self.def {
+            let (idx, (_local_id, data)) = self
+                .params
+                .types
+                .iter()
+                .enumerate()
+                .find(|(_, (idx, _))| *idx == param.local_id)
+                .unwrap();
+            let (_total, parent_len, _child) = self.len_split();
+            return ((parent_len + idx) as u32, data);
+        }
+        self.parent_generics.as_ref().unwrap().find_param(param)
+    }
+}
+
+fn parent_generic_def(db: &impl DefDatabase, def: GenericDefId) -> Option<GenericDefId> {
+    let container = match def {
+        GenericDefId::FunctionId(it) => it.lookup(db).container,
+        GenericDefId::TypeAliasId(it) => it.lookup(db).container,
+        GenericDefId::ConstId(it) => it.lookup(db).container,
+        GenericDefId::EnumVariantId(it) => return Some(it.parent.into()),
+        GenericDefId::AdtId(_) | GenericDefId::TraitId(_) | GenericDefId::ImplId(_) => return None,
+    };
+
+    match container {
+        ContainerId::ImplId(it) => Some(it.into()),
+        ContainerId::TraitId(it) => Some(it.into()),
+        ContainerId::ModuleId(_) => None,
+    }
+}
diff --git a/crates/ra_ide/src/display/navigation_target.rs b/crates/ra_ide/src/display/navigation_target.rs
index add11fbc3..6a6b49afd 100644
--- a/crates/ra_ide/src/display/navigation_target.rs
+++ b/crates/ra_ide/src/display/navigation_target.rs
@@ -6,7 +6,7 @@ use ra_db::{FileId, SourceDatabase};
 use ra_syntax::{
     ast::{self, DocCommentsOwner, NameOwner},
     match_ast, AstNode, SmolStr,
-    SyntaxKind::{self, BIND_PAT},
+    SyntaxKind::{self, BIND_PAT, TYPE_PARAM},
     TextRange,
 };
 
@@ -351,6 +351,26 @@ impl ToNav for hir::Local {
     }
 }
 
+impl ToNav for hir::TypeParam {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        let range = match src.value {
+            Either::Left(it) => it.syntax().text_range(),
+            Either::Right(it) => it.syntax().text_range(),
+        };
+        NavigationTarget {
+            file_id: src.file_id.original_file(db),
+            name: self.name(db).to_string().into(),
+            kind: TYPE_PARAM,
+            full_range: range,
+            focus_range: None,
+            container_name: None,
+            description: None,
+            docs: None,
+        }
+    }
+}
+
 pub(crate) fn docs_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option<String> {
     let parse = db.parse(symbol.file_id);
     let node = symbol.ptr.to_node(parse.tree().syntax());
diff --git a/crates/ra_ide/src/goto_definition.rs b/crates/ra_ide/src/goto_definition.rs
index 76a741207..1b968134d 100644
--- a/crates/ra_ide/src/goto_definition.rs
+++ b/crates/ra_ide/src/goto_definition.rs
@@ -64,9 +64,11 @@ pub(crate) fn reference_definition(
 
     let name_kind = classify_name_ref(db, name_ref).map(|d| d.kind);
     match name_kind {
-        Some(Macro(mac)) => return Exact(mac.to_nav(db)),
-        Some(Field(field)) => return Exact(field.to_nav(db)),
-        Some(AssocItem(assoc)) => return Exact(assoc.to_nav(db)),
+        Some(Macro(it)) => return Exact(it.to_nav(db)),
+        Some(Field(it)) => return Exact(it.to_nav(db)),
+        Some(TypeParam(it)) => return Exact(it.to_nav(db)),
+        Some(AssocItem(it)) => return Exact(it.to_nav(db)),
+        Some(Local(it)) => return Exact(it.to_nav(db)),
         Some(Def(def)) => match NavigationTarget::from_def(db, def) {
             Some(nav) => return Exact(nav),
             None => return Approximate(vec![]),
@@ -77,10 +79,6 @@ pub(crate) fn reference_definition(
             // us to the actual type
             return Exact(imp.to_nav(db));
         }
-        Some(Local(local)) => return Exact(local.to_nav(db)),
-        Some(GenericParam(_)) => {
-            // FIXME: go to the generic param def
-        }
         None => {}
     };
 
@@ -689,8 +687,51 @@ mod tests {
                     fo<|>o();
                 }
             }
+            mod confuse_index { fn foo(); }
             ",
             "foo FN_DEF FileId(1) [52; 63) [55; 58)",
         );
     }
+
+    #[should_panic] // currently failing because of expr mapping problems
+    #[test]
+    fn goto_through_format() {
+        check_goto(
+            "
+            //- /lib.rs
+            #[macro_export]
+            macro_rules! format {
+                ($($arg:tt)*) => ($crate::fmt::format($crate::__export::format_args!($($arg)*)))
+            }
+            #[rustc_builtin_macro]
+            #[macro_export]
+            macro_rules! format_args {
+                ($fmt:expr) => ({ /* compiler built-in */ });
+                ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+            }
+            pub mod __export {
+                pub use crate::format_args;
+                fn foo() {} // for index confusion
+            }
+            fn foo() -> i8 {}
+            fn test() {
+                format!(\"{}\", fo<|>o())
+            }
+            ",
+            "foo FN_DEF FileId(1) [359; 376) [362; 365)",
+        );
+    }
+
+    #[test]
+    fn goto_for_type_param() {
+        check_goto(
+            "
+            //- /lib.rs
+            struct Foo<T> {
+                t: <|>T,
+            }
+            ",
+            "T TYPE_PARAM FileId(1) [11; 12)",
+        );
+    }
 }
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index d8185c688..d372ca758 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -138,7 +138,7 @@ fn hover_text_from_name_kind(
             *no_fallback = true;
             None
         }
-        GenericParam(_) | SelfType(_) => {
+        TypeParam(_) | SelfType(_) => {
             // FIXME: Hover for generic param
             None
         }
diff --git a/crates/ra_ide/src/inlay_hints.rs b/crates/ra_ide/src/inlay_hints.rs
index 59eced9d7..3730121af 100644
--- a/crates/ra_ide/src/inlay_hints.rs
+++ b/crates/ra_ide/src/inlay_hints.rs
@@ -122,18 +122,11 @@ fn get_leaf_pats(root_pat: ast::Pat) -> Vec<ast::Pat> {
 
     while let Some(maybe_leaf_pat) = pats_to_process.pop_front() {
         match &maybe_leaf_pat {
-            ast::Pat::BindPat(bind_pat) => {
-                if let Some(pat) = bind_pat.pat() {
-                    pats_to_process.push_back(pat);
-                } else {
-                    leaf_pats.push(maybe_leaf_pat);
-                }
-            }
-            ast::Pat::TuplePat(tuple_pat) => {
-                for arg_pat in tuple_pat.args() {
-                    pats_to_process.push_back(arg_pat);
-                }
-            }
+            ast::Pat::BindPat(bind_pat) => match bind_pat.pat() {
+                Some(pat) => pats_to_process.push_back(pat),
+                _ => leaf_pats.push(maybe_leaf_pat),
+            },
+            ast::Pat::TuplePat(tuple_pat) => pats_to_process.extend(tuple_pat.args()),
             ast::Pat::RecordPat(record_pat) => {
                 if let Some(pat_list) = record_pat.record_field_pat_list() {
                     pats_to_process.extend(
@@ -151,10 +144,9 @@ fn get_leaf_pats(root_pat: ast::Pat) -> Vec<ast::Pat> {
                 }
             }
             ast::Pat::TupleStructPat(tuple_struct_pat) => {
-                for arg_pat in tuple_struct_pat.args() {
-                    pats_to_process.push_back(arg_pat);
-                }
+                pats_to_process.extend(tuple_struct_pat.args())
             }
+            ast::Pat::RefPat(ref_pat) => pats_to_process.extend(ref_pat.pat()),
             _ => (),
         }
     }
@@ -163,9 +155,10 @@ fn get_leaf_pats(root_pat: ast::Pat) -> Vec<ast::Pat> {
 
 #[cfg(test)]
 mod tests {
-    use crate::mock_analysis::single_file;
     use insta::assert_debug_snapshot;
 
+    use crate::mock_analysis::single_file;
+
     #[test]
     fn let_statement() {
         let (analysis, file_id) = single_file(
@@ -202,6 +195,7 @@ fn main() {
 
     let test = (42, 'a');
     let (a, (b, c, (d, e), f)) = (2, (3, 4, (6.6, 7.7), 5));
+    let &x = &92;
 }"#,
         );
 
@@ -257,6 +251,11 @@ fn main() {
                 kind: TypeHint,
                 label: "f64",
             },
+            InlayHint {
+                range: [627; 628),
+                kind: TypeHint,
+                label: "i32",
+            },
         ]
         "###
         );
diff --git a/crates/ra_ide/src/references.rs b/crates/ra_ide/src/references.rs
index 3e7bfd872..e3ecde50d 100644
--- a/crates/ra_ide/src/references.rs
+++ b/crates/ra_ide/src/references.rs
@@ -85,7 +85,7 @@ pub(crate) fn find_all_refs(
         NameKind::Def(def) => NavigationTarget::from_def(db, def)?,
         NameKind::SelfType(imp) => imp.to_nav(db),
         NameKind::Local(local) => local.to_nav(db),
-        NameKind::GenericParam(_) => return None,
+        NameKind::TypeParam(_) => return None,
     };
 
     let search_scope = {
diff --git a/crates/ra_ide/src/references/classify.rs b/crates/ra_ide/src/references/classify.rs
index b716d32e5..c1f091ec0 100644
--- a/crates/ra_ide/src/references/classify.rs
+++ b/crates/ra_ide/src/references/classify.rs
@@ -110,6 +110,15 @@ pub(crate) fn classify_name(db: &RootDatabase, name: InFile<&ast::Name>) -> Opti
                     kind: NameKind::Macro(def),
                 })
             },
+            ast::TypeParam(it) => {
+                let src = name.with_value(it);
+                let def = hir::TypeParam::from_source(db, src)?;
+                Some(NameDefinition {
+                    visibility: None,
+                    container: def.module(db),
+                    kind: NameKind::TypeParam(def),
+                })
+            },
             _ => None,
         }
     }
@@ -168,9 +177,8 @@ pub(crate) fn classify_name_ref(
             let kind = NameKind::Local(local);
             Some(NameDefinition { kind, container, visibility: None })
         }
-        PathResolution::GenericParam(par) => {
-            // FIXME: get generic param def
-            let kind = NameKind::GenericParam(par);
+        PathResolution::TypeParam(par) => {
+            let kind = NameKind::TypeParam(par);
             Some(NameDefinition { kind, container, visibility })
         }
         PathResolution::Macro(def) => {
diff --git a/crates/ra_ide/src/references/name_definition.rs b/crates/ra_ide/src/references/name_definition.rs
index 10d3a2364..8c67c8863 100644
--- a/crates/ra_ide/src/references/name_definition.rs
+++ b/crates/ra_ide/src/references/name_definition.rs
@@ -4,8 +4,8 @@
 //! Note that the reference search is possible for not all of the classified items.
 
 use hir::{
-    Adt, AssocItem, GenericParam, HasSource, ImplBlock, Local, MacroDef, Module, ModuleDef,
-    StructField, VariantDef,
+    Adt, AssocItem, HasSource, ImplBlock, Local, MacroDef, Module, ModuleDef, StructField,
+    TypeParam, VariantDef,
 };
 use ra_syntax::{ast, ast::VisibilityOwner};
 
@@ -19,7 +19,7 @@ pub enum NameKind {
     Def(ModuleDef),
     SelfType(ImplBlock),
     Local(Local),
-    GenericParam(GenericParam),
+    TypeParam(TypeParam),
 }
 
 #[derive(PartialEq, Eq)]
diff --git a/crates/ra_ide/src/snapshots/highlighting.html b/crates/ra_ide/src/snapshots/highlighting.html
index b39c4d371..4166a8f90 100644
--- a/crates/ra_ide/src/snapshots/highlighting.html
+++ b/crates/ra_ide/src/snapshots/highlighting.html
@@ -9,6 +9,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .parameter          { color: #94BFF3; }
 .builtin            { color: #DD6718; }
 .text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
 .attribute          { color: #94BFF3; }
 .literal            { color: #BFEBBF; }
 .macro              { color: #94BFF3; }
@@ -45,4 +46,12 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword">let</span> <span class="variable">z</span> = &<span class="variable.mut">y</span>;
 
     <span class="variable.mut">y</span>;
+}
+
+<span class="keyword">enum</span> <span class="type">E</span>&lt;<span class="type">X</span>&gt; {
+    <span class="constant">V</span>(<span class="type">X</span>)
+}
+
+<span class="keyword">impl</span>&lt;<span class="type">X</span>&gt; <span class="type">E</span>&lt;<span class="type">X</span>&gt; {
+    <span class="keyword">fn</span> <span class="function">new</span>&lt;<span class="type">T</span>&gt;() -&gt; <span class="type">E</span>&lt;<span class="type">T</span>&gt; {}
 }</code></pre>
\ No newline at end of file
diff --git a/crates/ra_ide/src/snapshots/rainbow_highlighting.html b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
index 79f11ea80..9dfbc8047 100644
--- a/crates/ra_ide/src/snapshots/rainbow_highlighting.html
+++ b/crates/ra_ide/src/snapshots/rainbow_highlighting.html
@@ -9,6 +9,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .parameter          { color: #94BFF3; }
 .builtin            { color: #DD6718; }
 .text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
 .attribute          { color: #94BFF3; }
 .literal            { color: #BFEBBF; }
 .macro              { color: #94BFF3; }
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index e6a79541f..7ecb1a027 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -225,8 +225,7 @@ fn highlight_name(db: &RootDatabase, name_kind: NameKind) -> &'static str {
         Def(hir::ModuleDef::Trait(_)) => "type",
         Def(hir::ModuleDef::TypeAlias(_)) => "type",
         Def(hir::ModuleDef::BuiltinType(_)) => "type",
-        SelfType(_) => "type",
-        GenericParam(_) => "type",
+        SelfType(_) | TypeParam(_) => "type",
         Local(local) => {
             if local.is_mut(db) {
                 "variable.mut"
@@ -255,6 +254,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .parameter          { color: #94BFF3; }
 .builtin            { color: #DD6718; }
 .text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
 .attribute          { color: #94BFF3; }
 .literal            { color: #BFEBBF; }
 .macro              { color: #94BFF3; }
@@ -303,6 +303,14 @@ fn main() {
 
     y;
 }
+
+enum E<X> {
+    V(X)
+}
+
+impl<X> E<X> {
+    fn new<T>() -> E<T> {}
+}
 "#
             .trim(),
         );
diff --git a/crates/ra_lsp_server/tests/heavy_tests/main.rs b/crates/ra_lsp_server/tests/heavy_tests/main.rs
index fec50bd25..cfbf16ea5 100644
--- a/crates/ra_lsp_server/tests/heavy_tests/main.rs
+++ b/crates/ra_lsp_server/tests/heavy_tests/main.rs
@@ -12,6 +12,7 @@ use ra_lsp_server::req::{
 };
 use serde_json::json;
 use tempfile::TempDir;
+use test_utils::skip_slow_tests;
 
 use crate::support::{project, Project};
 
@@ -20,6 +21,10 @@ const PROFILE: &'static str = "";
 
 #[test]
 fn completes_items_from_standard_library() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let project_start = Instant::now();
     let server = Project::with_fixture(
         r#"
@@ -50,6 +55,10 @@ use std::collections::Spam;
 
 #[test]
 fn test_runnables_no_project() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let server = project(
         r"
 //- lib.rs
@@ -99,6 +108,10 @@ fn foo() {
 
 #[test]
 fn test_runnables_project() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let code = r#"
 //- foo/Cargo.toml
 [package]
@@ -170,6 +183,10 @@ fn main() {}
 
 #[test]
 fn test_format_document() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let server = project(
         r#"
 //- Cargo.toml
@@ -222,6 +239,10 @@ pub use std::collections::HashMap;
 
 #[test]
 fn test_format_document_2018() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let server = project(
         r#"
 //- Cargo.toml
@@ -277,8 +298,13 @@ pub use std::collections::HashMap;
         ]),
     );
 }
+
 #[test]
 fn test_missing_module_code_action() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let server = project(
         r#"
 //- Cargo.toml
@@ -337,6 +363,10 @@ fn main() {}
 
 #[test]
 fn test_missing_module_code_action_in_json_project() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let tmp_dir = TempDir::new().unwrap();
 
     let path = tmp_dir.path();
@@ -412,6 +442,10 @@ fn main() {{}}
 
 #[test]
 fn diagnostics_dont_block_typing() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let librs: String = (0..10).map(|i| format!("mod m{};", i)).collect();
     let libs: String = (0..10).map(|i| format!("//- src/m{}.rs\nfn foo() {{}}\n\n", i)).collect();
     let server = Project::with_fixture(&format!(
@@ -480,6 +514,10 @@ fn main() {{}}
 
 #[test]
 fn preserves_dos_line_endings() {
+    if skip_slow_tests() {
+        return;
+    }
+
     let server = Project::with_fixture(
         &"
 //- Cargo.toml
diff --git a/crates/ra_syntax/src/ptr.rs b/crates/ra_syntax/src/ptr.rs
index e049fce61..db6230aab 100644
--- a/crates/ra_syntax/src/ptr.rs
+++ b/crates/ra_syntax/src/ptr.rs
@@ -1,6 +1,10 @@
 //! FIXME: write short doc here
 
-use std::{iter::successors, marker::PhantomData};
+use std::{
+    hash::{Hash, Hasher},
+    iter::successors,
+    marker::PhantomData,
+};
 
 use crate::{AstNode, SyntaxKind, SyntaxNode, TextRange};
 
@@ -43,7 +47,7 @@ impl SyntaxNodePtr {
 }
 
 /// Like `SyntaxNodePtr`, but remembers the type of node
-#[derive(Debug, Hash)]
+#[derive(Debug)]
 pub struct AstPtr<N: AstNode> {
     raw: SyntaxNodePtr,
     _ty: PhantomData<fn() -> N>,
@@ -64,6 +68,12 @@ impl<N: AstNode> PartialEq for AstPtr<N> {
     }
 }
 
+impl<N: AstNode> Hash for AstPtr<N> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.raw.hash(state)
+    }
+}
+
 impl<N: AstNode> AstPtr<N> {
     pub fn new(node: &N) -> AstPtr<N> {
         AstPtr { raw: SyntaxNodePtr::new(node.syntax()), _ty: PhantomData }
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index 1244ea8cf..657ddf2a6 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -356,6 +356,17 @@ pub fn read_text(path: &Path) -> String {
         .replace("\r\n", "\n")
 }
 
+pub fn skip_slow_tests() -> bool {
+    let should_skip = std::env::var("CI").is_err() && std::env::var("RUN_SLOW_TESTS").is_err();
+    if should_skip {
+        eprintln!("ignoring slow test")
+    } else {
+        let path = project_dir().join("./target/.slow_tests_cookie");
+        fs::write(&path, ".").unwrap();
+    }
+    should_skip
+}
+
 const REWRITE: bool = false;
 
 fn assert_equal_text(expected: &str, actual: &str, path: &Path) {