113 files changed, 4034 insertions, 2169 deletions
diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
index e270c5d60..1908bdec9 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_ctx.rs
@@ -1,11 +1,11 @@
-//! FIXME: write short doc here
+//! This module defines `AssistCtx` -- the API surface that is exposed to assists.
 use hir::db::HirDatabase;
 use ra_db::FileRange;
 use ra_fmt::{leading_indent, reindent};
 use ra_syntax::{
    algo::{self, find_covering_element, find_node_at_offset},
-    AstNode, SourceFile, SyntaxElement, SyntaxNode, SyntaxToken, TextRange, TextUnit,
+    AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextUnit,
    TokenAtOffset,
 };
 use ra_text_edit::TextEditBuilder;
@@ -14,8 +14,8 @@ use crate::{AssistAction, AssistId, AssistLabel};
 #[derive(Clone, Debug)]
 pub(crate) enum Assist {
-    Unresolved(Vec<AssistLabel>),
+    Unresolved { label: AssistLabel },
-    Resolved(Vec<(AssistLabel, AssistAction)>),
+    Resolved { label: AssistLabel, action: AssistAction },
 }
 /// `AssistCtx` allows to apply an assist or check if it could be applied.
@@ -54,7 +54,6 @@ pub(crate) struct AssistCtx<'a, DB> {
    pub(crate) frange: FileRange,
    source_file: SourceFile,
    should_compute_edit: bool,
-    assist: Assist,
 }
 impl<'a, DB> Clone for AssistCtx<'a, DB> {
@@ -64,7 +63,6 @@ impl<'a, DB> Clone for AssistCtx<'a, DB> {
            frange: self.frange,
            source_file: self.source_file.clone(),
            should_compute_edit: self.should_compute_edit,
-            assist: self.assist.clone(),
        }
    }
 }
@@ -75,43 +73,41 @@ impl<'a, DB: HirDatabase> AssistCtx<'a, DB> {
        F: FnOnce(AssistCtx<DB>) -> T,
    {
        let parse = db.parse(frange.file_id);
-        let assist =
-            if should_compute_edit { Assist::Resolved(vec![]) } else { Assist::Unresolved(vec![]) };
-        let ctx = AssistCtx { db, frange, source_file: parse.tree(), should_compute_edit, assist };
+        let ctx = AssistCtx { db, frange, source_file: parse.tree(), should_compute_edit };
        f(ctx)
    }
-    pub(crate) fn add_action(
+    pub(crate) fn add_assist(
-        &mut self,
+        self,
        id: AssistId,
        label: impl Into<String>,
        f: impl FnOnce(&mut AssistBuilder),
-    ) -> &mut Self {
+    ) -> Option<Assist> {
        let label = AssistLabel { label: label.into(), id };
-        match &mut self.assist {
+        let assist = if self.should_compute_edit {
-            Assist::Unresolved(labels) => labels.push(label),
+            let action = {
-            Assist::Resolved(labels_actions) => {
+                let mut edit = AssistBuilder::default();
-                let action = {
+                f(&mut edit);
-                    let mut edit = AssistBuilder::default();
+                edit.build()
-                    f(&mut edit);
+            };
-                    edit.build()
+            Assist::Resolved { label, action }
-                };
+        } else {
-                labels_actions.push((label, action));
+            Assist::Unresolved { label }
-            }
+        };
-        }
-        self
-    }
-    pub(crate) fn build(self) -> Option<Assist> {
+        Some(assist)
-        Some(self.assist)
    }
    pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
        self.source_file.syntax().token_at_offset(self.frange.range.start())
    }
-    pub(crate) fn node_at_offset<N: AstNode>(&self) -> Option<N> {
+    pub(crate) fn find_token_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> {
+        self.token_at_offset().find(|it| it.kind() == kind)
+    }
+    pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> {
        find_node_at_offset(self.source_file.syntax(), self.frange.range.start())
    }
    pub(crate) fn covering_element(&self) -> SyntaxElement {
diff --git a/crates/ra_assists/src/assists/add_derive.rs b/crates/ra_assists/src/assists/add_derive.rs
index 77ecc33c9..764b17bd8 100644
--- a/crates/ra_assists/src/assists/add_derive.rs
+++ b/crates/ra_assists/src/assists/add_derive.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast::{self, AstNode, AttrsOwner},
@@ -9,10 +7,28 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn add_derive(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: add_derive
-    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+//
+// Adds a new `#[derive()]` clause to a struct or enum.
+//
+// ```
+// struct Point {
+//     x: u32,
+//     y: u32,<|>
+// }
+// ```
+// ->
+// ```
+// #[derive()]
+// struct Point {
+//     x: u32,
+//     y: u32,
+// }
+// ```
+pub(crate) fn add_derive(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
    let node_start = derive_insertion_offset(&nominal)?;
-    ctx.add_action(AssistId("add_derive"), "add `#[derive]`", |edit| {
+    ctx.add_assist(AssistId("add_derive"), "add `#[derive]`", |edit| {
        let derive_attr = nominal
            .attrs()
            .filter_map(|x| x.as_simple_call())
@@ -28,9 +44,7 @@ pub(crate) fn add_derive(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist>
        };
        edit.target(nominal.syntax().text_range());
        edit.set_cursor(offset)
-    });
+    })
-    ctx.build()
 }
 // Insert `derive` after doc comments.
diff --git a/crates/ra_assists/src/assists/add_explicit_type.rs b/crates/ra_assists/src/assists/add_explicit_type.rs
index 8c83dc987..ddda1a0f2 100644
--- a/crates/ra_assists/src/assists/add_explicit_type.rs
+++ b/crates/ra_assists/src/assists/add_explicit_type.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::{db::HirDatabase, HirDisplay, Ty};
 use ra_syntax::{
    ast::{self, AstNode, LetStmt, NameOwner},
@@ -8,9 +6,23 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
-/// Add explicit type assist.
+// Assist: add_explicit_type
-pub(crate) fn add_explicit_type(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+//
-    let stmt = ctx.node_at_offset::<LetStmt>()?;
+// Specify type for a let binding.
+//
+// ```
+// fn main() {
+//     let x<|> = 92;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let x: i32 = 92;
+// }
+// ```
+pub(crate) fn add_explicit_type(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let stmt = ctx.find_node_at_offset::<LetStmt>()?;
    let expr = stmt.initializer()?;
    let pat = stmt.pat()?;
    // Must be a binding
@@ -35,11 +47,10 @@ pub(crate) fn add_explicit_type(mut ctx: AssistCtx<impl HirDatabase>) -> Option<
        return None;
    }
-    ctx.add_action(AssistId("add_explicit_type"), "add explicit type", |edit| {
+    ctx.add_assist(AssistId("add_explicit_type"), "add explicit type", |edit| {
        edit.target(pat_range);
        edit.insert(name_range.end(), format!(": {}", ty.display(db)));
-    });
+    })
-    ctx.build()
 }
 /// Returns true if any type parameter is unknown
diff --git a/crates/ra_assists/src/assists/add_impl.rs b/crates/ra_assists/src/assists/add_impl.rs
index 94801fbc9..7da0cfd0d 100644
--- a/crates/ra_assists/src/assists/add_impl.rs
+++ b/crates/ra_assists/src/assists/add_impl.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use format_buf::format;
 use hir::db::HirDatabase;
 use join_to_string::join;
@@ -10,10 +8,29 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn add_impl(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: add_impl
-    let nominal = ctx.node_at_offset::<ast::NominalDef>()?;
+//
+// Adds a new inherent impl for a type.
+//
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,<|>
+// }
+// ```
+// ->
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,
+// }
+//
+// impl<T: Clone> Ctx<T> {
+//
+// }
+// ```
+pub(crate) fn add_impl(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
    let name = nominal.name()?;
-    ctx.add_action(AssistId("add_impl"), "add impl", |edit| {
+    ctx.add_assist(AssistId("add_impl"), "add impl", |edit| {
        edit.target(nominal.syntax().text_range());
        let type_params = nominal.type_param_list();
        let start_offset = nominal.syntax().text_range().end();
@@ -37,9 +54,7 @@ pub(crate) fn add_impl(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
        edit.set_cursor(start_offset + TextUnit::of_str(&buf));
        buf.push_str("\n}");
        edit.insert(start_offset, buf);
-    });
+    })
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/auto_import.rs b/crates/ra_assists/src/assists/add_import.rs
index 02c58e7c6..363ade016 100644
--- a/crates/ra_assists/src/assists/auto_import.rs
+++ b/crates/ra_assists/src/assists/add_import.rs
@@ -1,18 +1,81 @@
-//! FIXME: write short doc here
 use hir::{self, db::HirDatabase};
-use ra_text_edit::TextEditBuilder;
-use crate::{
-    assist_ctx::{Assist, AssistCtx},
-    AssistId,
-};
 use ra_syntax::{
    ast::{self, NameOwner},
    AstNode, Direction, SmolStr,
    SyntaxKind::{PATH, PATH_SEGMENT},
    SyntaxNode, TextRange, T,
 };
+use ra_text_edit::TextEditBuilder;
+use crate::{
+    assist_ctx::{Assist, AssistCtx},
+    AssistId,
+};
+/// This function produces sequence of text edits into edit
+/// to import the target path in the most appropriate scope given
+/// the cursor position
+pub fn auto_import_text_edit(
+    // Ideally the position of the cursor, used to
+    position: &SyntaxNode,
+    // The statement to use as anchor (last resort)
+    anchor: &SyntaxNode,
+    // The path to import as a sequence of strings
+    target: &[SmolStr],
+    edit: &mut TextEditBuilder,
+) {
+    let container = position.ancestors().find_map(|n| {
+        if let Some(module) = ast::Module::cast(n.clone()) {
+            return module.item_list().map(|it| it.syntax().clone());
+        }
+        ast::SourceFile::cast(n).map(|it| it.syntax().clone())
+    });
+    if let Some(container) = container {
+        let action = best_action_for_target(container, anchor.clone(), target);
+        make_assist(&action, target, edit);
+    }
+}
+// Assist: add_import
+//
+// Adds a use statement for a given fully-qualified path.
+//
+// ```
+// fn process(map: std::collections::<|>HashMap<String, String>) {}
+// ```
+// ->
+// ```
+// use std::collections::HashMap;
+//
+// fn process(map: HashMap<String, String>) {}
+// ```
+pub(crate) fn add_import(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let path: ast::Path = ctx.find_node_at_offset()?;
+    // We don't want to mess with use statements
+    if path.syntax().ancestors().find_map(ast::UseItem::cast).is_some() {
+        return None;
+    }
+    let hir_path = hir::Path::from_ast(path.clone())?;
+    let segments = collect_hir_path_segments(&hir_path)?;
+    if segments.len() < 2 {
+        return None;
+    }
+    let module = path.syntax().ancestors().find_map(ast::Module::cast);
+    let position = match module.and_then(|it| it.item_list()) {
+        Some(item_list) => item_list.syntax().clone(),
+        None => {
+            let current_file = path.syntax().ancestors().find_map(ast::SourceFile::cast)?;
+            current_file.syntax().clone()
+        }
+    };
+    ctx.add_assist(AssistId("add_import"), format!("import {}", fmt_segments(&segments)), |edit| {
+        apply_auto_import(&position, &path, &segments, edit.text_edit_builder());
+    })
+}
 fn collect_path_segments_raw(
    segments: &mut Vec<ast::PathSegment>,
@@ -61,9 +124,9 @@ fn fmt_segments_raw(segments: &[SmolStr], buf: &mut String) {
    }
 }
-// Returns the numeber of common segments.
+/// Returns the number of common segments.
 fn compare_path_segments(left: &[SmolStr], right: &[ast::PathSegment]) -> usize {
-    left.iter().zip(right).filter(|(l, r)| compare_path_segment(l, r)).count()
+    left.iter().zip(right).take_while(|(l, r)| compare_path_segment(l, r)).count()
 }
 fn compare_path_segment(a: &SmolStr, b: &ast::PathSegment) -> bool {
@@ -84,7 +147,7 @@ fn compare_path_segment_with_name(a: &SmolStr, b: &ast::Name) -> bool {
    a == b.text()
 }
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 enum ImportAction {
    Nothing,
    // Add a brand new use statement.
@@ -154,9 +217,17 @@ impl ImportAction {
            (
                ImportAction::AddNestedImport { common_segments: n, .. },
                ImportAction::AddInTreeList { common_segments: m, .. },
-            ) => n > m,
+            )
-            (
+            | (
+                ImportAction::AddInTreeList { common_segments: n, .. },
+                ImportAction::AddNestedImport { common_segments: m, .. },
+            )
+            | (
                ImportAction::AddInTreeList { common_segments: n, .. },
+                ImportAction::AddInTreeList { common_segments: m, .. },
+            )
+            | (
+                ImportAction::AddNestedImport { common_segments: n, .. },
                ImportAction::AddNestedImport { common_segments: m, .. },
            ) => n > m,
            (ImportAction::AddInTreeList { .. }, _) => true,
@@ -226,7 +297,7 @@ fn walk_use_tree_for_best_action(
        common if common == left.len() && left.len() == right.len() => {
            // e.g: target is std::fmt and we can have
            // 1- use std::fmt;
-            // 2- use std::fmt:{ ... }
+            // 2- use std::fmt::{ ... }
            if let Some(list) = tree_list {
                // In case 2 we need to add self to the nested list
                // unless it's already there
@@ -474,7 +545,7 @@ fn make_assist_add_nested_import(
        if add_colon_colon {
            buf.push_str("::");
        }
-        buf.push_str("{ ");
+        buf.push_str("{");
        if add_self {
            buf.push_str("self, ");
        }
@@ -505,7 +576,7 @@ fn apply_auto_import(
    }
 }
-pub fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
+fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
    let mut ps = Vec::<SmolStr>::with_capacity(10);
    match path.kind {
        hir::PathKind::Abs => ps.push("".into()),
@@ -521,87 +592,16 @@ pub fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
    Some(ps)
 }
-// This function produces sequence of text edits into edit
-// to import the target path in the most appropriate scope given
-// the cursor position
-pub fn auto_import_text_edit(
-    // Ideally the position of the cursor, used to
-    position: &SyntaxNode,
-    // The statement to use as anchor (last resort)
-    anchor: &SyntaxNode,
-    // The path to import as a sequence of strings
-    target: &[SmolStr],
-    edit: &mut TextEditBuilder,
-) {
-    let container = position.ancestors().find_map(|n| {
-        if let Some(module) = ast::Module::cast(n.clone()) {
-            return module.item_list().map(|it| it.syntax().clone());
-        }
-        ast::SourceFile::cast(n).map(|it| it.syntax().clone())
-    });
-    if let Some(container) = container {
-        let action = best_action_for_target(container, anchor.clone(), target);
-        make_assist(&action, target, edit);
-    }
-}
-pub(crate) fn auto_import(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
-    let path: ast::Path = ctx.node_at_offset()?;
-    // We don't want to mess with use statements
-    if path.syntax().ancestors().find_map(ast::UseItem::cast).is_some() {
-        return None;
-    }
-    let hir_path = hir::Path::from_ast(path.clone())?;
-    let segments = collect_hir_path_segments(&hir_path)?;
-    if segments.len() < 2 {
-        return None;
-    }
-    if let Some(module) = path.syntax().ancestors().find_map(ast::Module::cast) {
-        if let (Some(item_list), Some(name)) = (module.item_list(), module.name()) {
-            ctx.add_action(
-                AssistId("auto_import"),
-                format!("import {} in mod {}", fmt_segments(&segments), name.text()),
-                |edit| {
-                    apply_auto_import(
-                        item_list.syntax(),
-                        &path,
-                        &segments,
-                        edit.text_edit_builder(),
-                    );
-                },
-            );
-        }
-    } else {
-        let current_file = path.syntax().ancestors().find_map(ast::SourceFile::cast)?;
-        ctx.add_action(
-            AssistId("auto_import"),
-            format!("import {} in the current file", fmt_segments(&segments)),
-            |edit| {
-                apply_auto_import(
-                    current_file.syntax(),
-                    &path,
-                    &segments,
-                    edit.text_edit_builder(),
-                );
-            },
-        );
-    }
-    ctx.build()
-}
 #[cfg(test)]
 mod tests {
-    use super::*;
    use crate::helpers::{check_assist, check_assist_not_applicable};
+    use super::*;
    #[test]
    fn test_auto_import_add_use_no_anchor() {
        check_assist(
-            auto_import,
+            add_import,
            "
 std::fmt::Debug<|>
    ",
@@ -615,7 +615,7 @@ Debug<|>
    #[test]
    fn test_auto_import_add_use_no_anchor_with_item_below() {
        check_assist(
-            auto_import,
+            add_import,
            "
 std::fmt::Debug<|>
@@ -636,7 +636,7 @@ fn main() {
    #[test]
    fn test_auto_import_add_use_no_anchor_with_item_above() {
        check_assist(
-            auto_import,
+            add_import,
            "
 fn main() {
 }
@@ -657,7 +657,7 @@ Debug<|>
    #[test]
    fn test_auto_import_add_use_no_anchor_2seg() {
        check_assist(
-            auto_import,
+            add_import,
            "
 std::fmt<|>::Debug
    ",
@@ -672,7 +672,7 @@ fmt<|>::Debug
    #[test]
    fn test_auto_import_add_use() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use stdx;
@@ -692,7 +692,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_file_use_other_anchor() {
        check_assist(
-            auto_import,
+            add_import,
            "
 impl std::fmt::Debug<|> for Foo {
 }
@@ -709,7 +709,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_add_use_other_anchor_indent() {
        check_assist(
-            auto_import,
+            add_import,
            "
    impl std::fmt::Debug<|> for Foo {
    }
@@ -726,7 +726,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_split_different() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt;
@@ -734,7 +734,7 @@ impl std::io<|> for Foo {
 }
    ",
            "
-use std::{ io, fmt};
+use std::{io, fmt};
 impl io<|> for Foo {
 }
@@ -745,7 +745,7 @@ impl io<|> for Foo {
    #[test]
    fn test_auto_import_split_self_for_use() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt;
@@ -753,7 +753,7 @@ impl std::fmt::Debug<|> for Foo {
 }
    ",
            "
-use std::fmt::{ self, Debug, };
+use std::fmt::{self, Debug, };
 impl Debug<|> for Foo {
 }
@@ -764,7 +764,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_split_self_for_target() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::Debug;
@@ -772,7 +772,7 @@ impl std::fmt<|> for Foo {
 }
    ",
            "
-use std::fmt::{ self, Debug};
+use std::fmt::{self, Debug};
 impl fmt<|> for Foo {
 }
@@ -783,7 +783,7 @@ impl fmt<|> for Foo {
    #[test]
    fn test_auto_import_add_to_nested_self_nested() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::{Debug, nested::{Display}};
@@ -802,7 +802,7 @@ impl nested<|> for Foo {
    #[test]
    fn test_auto_import_add_to_nested_self_already_included() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::{Debug, nested::{self, Display}};
@@ -821,7 +821,7 @@ impl nested<|> for Foo {
    #[test]
    fn test_auto_import_add_to_nested_nested() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::{Debug, nested::{Display}};
@@ -840,7 +840,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_split_common_target_longer() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::Debug;
@@ -848,7 +848,7 @@ impl std::fmt::nested::Display<|> for Foo {
 }
 ",
            "
-use std::fmt::{ nested::Display, Debug};
+use std::fmt::{nested::Display, Debug};
 impl Display<|> for Foo {
 }
@@ -859,7 +859,7 @@ impl Display<|> for Foo {
    #[test]
    fn test_auto_import_split_common_use_longer() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt::nested::Debug;
@@ -867,7 +867,7 @@ impl std::fmt::Display<|> for Foo {
 }
 ",
            "
-use std::fmt::{ Display, nested::Debug};
+use std::fmt::{Display, nested::Debug};
 impl Display<|> for Foo {
 }
@@ -876,9 +876,32 @@ impl Display<|> for Foo {
    }
    #[test]
+    fn test_auto_import_use_nested_import() {
+        check_assist(
+            add_import,
+            "
+use crate::{
+    ty::{Substs, Ty},
+    AssocItem,
+};
+fn foo() { crate::ty::lower<|>::trait_env() }
+",
+            "
+use crate::{
+    ty::{Substs, Ty, lower},
+    AssocItem,
+};
+fn foo() { lower<|>::trait_env() }
+",
+        );
+    }
+    #[test]
    fn test_auto_import_alias() {
        check_assist(
-            auto_import,
+            add_import,
            "
 use std::fmt as foo;
@@ -897,7 +920,7 @@ impl Debug<|> for Foo {
    #[test]
    fn test_auto_import_not_applicable_one_segment() {
        check_assist_not_applicable(
-            auto_import,
+            add_import,
            "
 impl foo<|> for Foo {
 }
@@ -908,7 +931,7 @@ impl foo<|> for Foo {
    #[test]
    fn test_auto_import_not_applicable_in_use() {
        check_assist_not_applicable(
-            auto_import,
+            add_import,
            "
 use std::fmt<|>;
 ",
@@ -918,7 +941,7 @@ use std::fmt<|>;
    #[test]
    fn test_auto_import_add_use_no_anchor_in_mod_mod() {
        check_assist(
-            auto_import,
+            add_import,
            "
 mod foo {
    mod bar {
diff --git a/crates/ra_assists/src/assists/add_missing_impl_members.rs b/crates/ra_assists/src/assists/add_missing_impl_members.rs
index 565b96fb5..41de23921 100644
--- a/crates/ra_assists/src/assists/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/assists/add_missing_impl_members.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::{db::HirDatabase, HasSource};
 use ra_syntax::{
    ast::{self, edit, make, AstNode, NameOwner},
@@ -14,6 +12,34 @@ enum AddMissingImplMembersMode {
    NoDefaultMethods,
 }
+// Assist: add_impl_missing_members
+//
+// Adds scaffold for required impl members.
+//
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {<|>
+//
+// }
+// ```
+// ->
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     fn foo(&self) { unimplemented!() }
+//
+// }
+// ```
 pub(crate) fn add_missing_impl_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    add_missing_impl_members_inner(
        ctx,
@@ -23,6 +49,38 @@ pub(crate) fn add_missing_impl_members(ctx: AssistCtx<impl HirDatabase>) -> Opti
    )
 }
+// Assist: add_impl_default_members
+//
+// Adds scaffold for overriding default impl members.
+//
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     Type X = ();
+//     fn foo(&self) {}<|>
+//
+// }
+// ```
+// ->
+// ```
+// trait T {
+//     Type X;
+//     fn foo(&self);
+//     fn bar(&self) {}
+// }
+//
+// impl T for () {
+//     Type X = ();
+//     fn foo(&self) {}
+//     fn bar(&self) {}
+//
+// }
+// ```
 pub(crate) fn add_missing_default_members(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    add_missing_impl_members_inner(
        ctx,
@@ -33,12 +91,12 @@ pub(crate) fn add_missing_default_members(ctx: AssistCtx<impl HirDatabase>) -> O
 }
 fn add_missing_impl_members_inner(
-    mut ctx: AssistCtx<impl HirDatabase>,
+    ctx: AssistCtx<impl HirDatabase>,
    mode: AddMissingImplMembersMode,
    assist_id: &'static str,
    label: &'static str,
 ) -> Option<Assist> {
-    let impl_node = ctx.node_at_offset::<ast::ImplBlock>()?;
+    let impl_node = ctx.find_node_at_offset::<ast::ImplBlock>()?;
    let impl_item_list = impl_node.item_list()?;
    let trait_def = {
@@ -75,7 +133,7 @@ fn add_missing_impl_members_inner(
        return None;
    }
-    ctx.add_action(AssistId(assist_id), label, |edit| {
+    ctx.add_assist(AssistId(assist_id), label, |edit| {
        let n_existing_items = impl_item_list.impl_items().count();
        let items = missing_items
            .into_iter()
@@ -92,9 +150,7 @@ fn add_missing_impl_members_inner(
        edit.replace_ast(impl_item_list, new_impl_item_list);
        edit.set_cursor(cursor_position);
-    });
+    })
-    ctx.build()
 }
 fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
diff --git a/crates/ra_assists/src/assists/apply_demorgan.rs b/crates/ra_assists/src/assists/apply_demorgan.rs
index 5f2b0dd18..068da1774 100644
--- a/crates/ra_assists/src/assists/apply_demorgan.rs
+++ b/crates/ra_assists/src/assists/apply_demorgan.rs
@@ -1,20 +1,30 @@
-//! This contains the functions associated with the demorgan assist.
-//! This assist transforms boolean expressions of the form `!a || !b` into
-//! `!(a && b)`.
 use hir::db::HirDatabase;
 use ra_syntax::ast::{self, AstNode};
 use ra_syntax::SyntaxNode;
 use crate::{Assist, AssistCtx, AssistId};
-/// Assist for applying demorgan's law
+// Assist: apply_demorgan
-///
+//
-/// This transforms expressions of the form `!l || !r` into `!(l && r)`.
+// Apply [De Morgan's law](https://en.wikipedia.org/wiki/De_Morgan%27s_laws).
-/// This also works with `&&`. This assist can only be applied with the cursor
+// This transforms expressions of the form `!l || !r` into `!(l && r)`.
-/// on either `||` or `&&`, with both operands being a negation of some kind.
+// This also works with `&&`. This assist can only be applied with the cursor
-/// This means something of the form `!x` or `x != y`.
+// on either `||` or `&&`, with both operands being a negation of some kind.
-pub(crate) fn apply_demorgan(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// This means something of the form `!x` or `x != y`.
-    let expr = ctx.node_at_offset::<ast::BinExpr>()?;
+//
+// ```
+// fn main() {
+//     if x != 4 ||<|> !y {}
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     if !(x == 4 && y) {}
+// }
+// ```
+pub(crate) fn apply_demorgan(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
    let op = expr.op_kind()?;
    let op_range = expr.op_token()?.text_range();
    let opposite_op = opposite_logic_op(op)?;
@@ -29,13 +39,12 @@ pub(crate) fn apply_demorgan(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Ass
    let not_lhs = undo_negation(lhs)?;
    let not_rhs = undo_negation(rhs)?;
-    ctx.add_action(AssistId("apply_demorgan"), "apply demorgan's law", |edit| {
+    ctx.add_assist(AssistId("apply_demorgan"), "apply demorgan's law", |edit| {
        edit.target(op_range);
        edit.replace(op_range, opposite_op);
        edit.replace(lhs_range, format!("!({}", not_lhs));
        edit.replace(rhs_range, format!("{})", not_rhs));
-    });
+    })
-    ctx.build()
 }
 // Return the opposite text for a given logical operator, if it makes sense
diff --git a/crates/ra_assists/src/assists/change_visibility.rs b/crates/ra_assists/src/assists/change_visibility.rs
index df92c6b67..132c9dc1d 100644
--- a/crates/ra_assists/src/assists/change_visibility.rs
+++ b/crates/ra_assists/src/assists/change_visibility.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast::{self, NameOwner, VisibilityOwner},
@@ -13,14 +11,25 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
+// Assist: change_visibility
+//
+// Adds or changes existing visibility specifier.
+//
+// ```
+// <|>fn frobnicate() {}
+// ```
+// ->
+// ```
+// pub(crate) fn frobnicate() {}
+// ```
 pub(crate) fn change_visibility(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
-    if let Some(vis) = ctx.node_at_offset::<ast::Visibility>() {
+    if let Some(vis) = ctx.find_node_at_offset::<ast::Visibility>() {
        return change_vis(ctx, vis);
    }
    add_vis(ctx)
 }
-fn add_vis(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+fn add_vis(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    let item_keyword = ctx.token_at_offset().find(|leaf| match leaf.kind() {
        T![fn] | T![mod] | T![struct] | T![enum] | T![trait] => true,
        _ => false,
@@ -48,13 +57,11 @@ fn add_vis(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
        (vis_offset(field.syntax()), ident.text_range())
    };
-    ctx.add_action(AssistId("change_visibility"), "make pub(crate)", |edit| {
+    ctx.add_assist(AssistId("change_visibility"), "make pub(crate)", |edit| {
        edit.target(target);
        edit.insert(offset, "pub(crate) ");
        edit.set_cursor(offset);
-    });
+    })
-    ctx.build()
 }
 fn vis_offset(node: &SyntaxNode) -> TextUnit {
@@ -68,24 +75,20 @@ fn vis_offset(node: &SyntaxNode) -> TextUnit {
        .unwrap_or_else(|| node.text_range().start())
 }
-fn change_vis(mut ctx: AssistCtx<impl HirDatabase>, vis: ast::Visibility) -> Option<Assist> {
+fn change_vis(ctx: AssistCtx<impl HirDatabase>, vis: ast::Visibility) -> Option<Assist> {
    if vis.syntax().text() == "pub" {
-        ctx.add_action(AssistId("change_visibility"), "change to pub(crate)", |edit| {
+        return ctx.add_assist(AssistId("change_visibility"), "change to pub(crate)", |edit| {
            edit.target(vis.syntax().text_range());
            edit.replace(vis.syntax().text_range(), "pub(crate)");
            edit.set_cursor(vis.syntax().text_range().start())
        });
-        return ctx.build();
    }
    if vis.syntax().text() == "pub(crate)" {
-        ctx.add_action(AssistId("change_visibility"), "change to pub", |edit| {
+        return ctx.add_assist(AssistId("change_visibility"), "change to pub", |edit| {
            edit.target(vis.syntax().text_range());
            edit.replace(vis.syntax().text_range(), "pub");
            edit.set_cursor(vis.syntax().text_range().start());
        });
-        return ctx.build();
    }
    None
 }
diff --git a/crates/ra_assists/src/assists/early_return.rs b/crates/ra_assists/src/assists/early_return.rs
index f7d7e12e7..ad6c5695a 100644
--- a/crates/ra_assists/src/assists/early_return.rs
+++ b/crates/ra_assists/src/assists/early_return.rs
@@ -1,26 +1,3 @@
-//! Assist: `convert_to_guarded_return`
-//!
-//! Replace a large conditional with a guarded return.
-//!
-//! ```text
-//! fn <|>main() {
-//!     if cond {
-//!         foo();
-//!         bar();
-//!     }
-//! }
-//! ```
-//! ->
-//! ```text
-//! fn main() {
-//!     if !cond {
-//!         return;
-//!     }
-//!     foo();
-//!     bar();
-//! }
-//! ```
 use std::ops::RangeInclusive;
 use hir::db::HirDatabase;
@@ -36,8 +13,30 @@ use crate::{
    AssistId,
 };
-pub(crate) fn convert_to_guarded_return(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: convert_to_guarded_return
-    let if_expr: ast::IfExpr = ctx.node_at_offset()?;
+//
+// Replace a large conditional with a guarded return.
+//
+// ```
+// fn main() {
+//     <|>if cond {
+//         foo();
+//         bar();
+//     }
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     if !cond {
+//         return;
+//     }
+//     foo();
+//     bar();
+// }
+// ```
+pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
    let expr = if_expr.condition()?.expr()?;
    let then_block = if_expr.then_branch()?.block()?;
    if if_expr.else_branch().is_some() {
@@ -51,7 +50,7 @@ pub(crate) fn convert_to_guarded_return(mut ctx: AssistCtx<impl HirDatabase>) ->
    }
    // check for early return and continue
-    let first_in_then_block = then_block.syntax().first_child()?.clone();
+    let first_in_then_block = then_block.syntax().first_child()?;
    if ast::ReturnExpr::can_cast(first_in_then_block.kind())
        || ast::ContinueExpr::can_cast(first_in_then_block.kind())
        || first_in_then_block
@@ -76,7 +75,7 @@ pub(crate) fn convert_to_guarded_return(mut ctx: AssistCtx<impl HirDatabase>) ->
    then_block.syntax().last_child_or_token().filter(|t| t.kind() == R_CURLY)?;
    let cursor_position = ctx.frange.range.start();
-    ctx.add_action(AssistId("convert_to_guarded_return"), "convert to guarded return", |edit| {
+    ctx.add_assist(AssistId("convert_to_guarded_return"), "convert to guarded return", |edit| {
        let if_indent_level = IndentLevel::from_node(&if_expr.syntax());
        let new_if_expr =
            if_indent_level.increase_indent(make::if_expression(&expr, early_expression));
@@ -106,8 +105,7 @@ pub(crate) fn convert_to_guarded_return(mut ctx: AssistCtx<impl HirDatabase>) ->
        edit.target(if_expr.syntax().text_range());
        edit.replace_ast(parent_block, ast::Block::cast(new_block).unwrap());
        edit.set_cursor(cursor_position);
-    });
+    })
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/fill_match_arms.rs b/crates/ra_assists/src/assists/fill_match_arms.rs
index e3f30b5de..2b74f355c 100644
--- a/crates/ra_assists/src/assists/fill_match_arms.rs
+++ b/crates/ra_assists/src/assists/fill_match_arms.rs
@@ -7,8 +7,32 @@ use ra_syntax::ast::{self, edit::IndentLevel, make, AstNode, NameOwner};
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn fill_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: fill_match_arms
-    let match_expr = ctx.node_at_offset::<ast::MatchExpr>()?;
+//
+// Adds missing clauses to a `match` expression.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         <|>
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } => (),
+//         Action::Stop => (),
+//     }
+// }
+// ```
+pub(crate) fn fill_match_arms(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let match_expr = ctx.find_node_at_offset::<ast::MatchExpr>()?;
    let match_arm_list = match_expr.match_arm_list()?;
    // We already have some match arms, so we don't provide any assists.
@@ -29,7 +53,7 @@ pub(crate) fn fill_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<As
    };
    let variant_list = enum_def.variant_list()?;
-    ctx.add_action(AssistId("fill_match_arms"), "fill match arms", |edit| {
+    ctx.add_assist(AssistId("fill_match_arms"), "fill match arms", |edit| {
        let indent_level = IndentLevel::from_node(match_arm_list.syntax());
        let new_arm_list = {
@@ -43,9 +67,7 @@ pub(crate) fn fill_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<As
        edit.target(match_expr.syntax().text_range());
        edit.set_cursor(expr.syntax().text_range().start());
        edit.replace_ast(match_arm_list, new_arm_list);
-    });
+    })
-    ctx.build()
 }
 fn is_trivial(arm: &ast::MatchArm) -> bool {
@@ -130,7 +152,7 @@ mod tests {
                    A::Bs => (),
                    A::Cs(_) => (),
                    A::Ds(_, _) => (),
-                    A::Es{ x, y } => (),
+                    A::Es { x, y } => (),
                }
            }
            "#,
@@ -183,7 +205,7 @@ mod tests {
            fn foo(a: &mut A) {
                match <|>a {
-                    A::Es{ x, y } => (),
+                    A::Es { x, y } => (),
                }
            }
            "#,
diff --git a/crates/ra_assists/src/assists/flip_binexpr.rs b/crates/ra_assists/src/assists/flip_binexpr.rs
index c51035282..386045eb0 100644
--- a/crates/ra_assists/src/assists/flip_binexpr.rs
+++ b/crates/ra_assists/src/assists/flip_binexpr.rs
@@ -1,13 +1,25 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::ast::{AstNode, BinExpr, BinOp};
 use crate::{Assist, AssistCtx, AssistId};
-/// Flip binary expression assist.
+// Assist: flip_binexpr
-pub(crate) fn flip_binexpr(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+//
-    let expr = ctx.node_at_offset::<BinExpr>()?;
+// Flips operands of a binary expression.
+//
+// ```
+// fn main() {
+//     let _ = 90 +<|> 2;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let _ = 2 + 90;
+// }
+// ```
+pub(crate) fn flip_binexpr(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let expr = ctx.find_node_at_offset::<BinExpr>()?;
    let lhs = expr.lhs()?.syntax().clone();
    let rhs = expr.rhs()?.syntax().clone();
    let op_range = expr.op_token()?.text_range();
@@ -22,16 +34,14 @@ pub(crate) fn flip_binexpr(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assis
        return None;
    }
-    ctx.add_action(AssistId("flip_binexpr"), "flip binary expression", |edit| {
+    ctx.add_assist(AssistId("flip_binexpr"), "flip binary expression", |edit| {
        edit.target(op_range);
        if let FlipAction::FlipAndReplaceOp(new_op) = action {
            edit.replace(op_range, new_op);
        }
        edit.replace(lhs.text_range(), rhs.text());
        edit.replace(rhs.text_range(), lhs.text());
-    });
+    })
-    ctx.build()
 }
 enum FlipAction {
diff --git a/crates/ra_assists/src/assists/flip_comma.rs b/crates/ra_assists/src/assists/flip_comma.rs
index e31cc5e7d..9be1c1dc6 100644
--- a/crates/ra_assists/src/assists/flip_comma.rs
+++ b/crates/ra_assists/src/assists/flip_comma.rs
@@ -1,12 +1,25 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{algo::non_trivia_sibling, Direction, T};
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn flip_comma(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: flip_comma
-    let comma = ctx.token_at_offset().find(|leaf| leaf.kind() == T![,])?;
+//
+// Flips two comma-separated items.
+//
+// ```
+// fn main() {
+//     ((1, 2),<|> (3, 4));
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     ((3, 4), (1, 2));
+// }
+// ```
+pub(crate) fn flip_comma(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let comma = ctx.find_token_at_offset(T![,])?;
    let prev = non_trivia_sibling(comma.clone().into(), Direction::Prev)?;
    let next = non_trivia_sibling(comma.clone().into(), Direction::Next)?;
@@ -16,13 +29,11 @@ pub(crate) fn flip_comma(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist>
        return None;
    }
-    ctx.add_action(AssistId("flip_comma"), "flip comma", |edit| {
+    ctx.add_assist(AssistId("flip_comma"), "flip comma", |edit| {
        edit.target(comma.text_range());
        edit.replace(prev.text_range(), next.to_string());
        edit.replace(next.text_range(), prev.to_string());
-    });
+    })
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/flip_trait_bound.rs b/crates/ra_assists/src/assists/flip_trait_bound.rs
new file mode 100644
index 000000000..6017b39dd
--- /dev/null
+++ b/crates/ra_assists/src/assists/flip_trait_bound.rs
@@ -0,0 +1,117 @@
+use hir::db::HirDatabase;
+use ra_syntax::{
+    algo::non_trivia_sibling,
+    ast::{self, AstNode},
+    Direction, T,
+};
+use crate::{Assist, AssistCtx, AssistId};
+// Assist: flip_trait_bound
+//
+// Flips two trait bounds.
+//
+// ```
+// fn foo<T: Clone +<|> Copy>() { }
+// ```
+// ->
+// ```
+// fn foo<T: Copy + Clone>() { }
+// ```
+pub(crate) fn flip_trait_bound(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    // We want to replicate the behavior of `flip_binexpr` by only suggesting
+    // the assist when the cursor is on a `+`
+    let plus = ctx.find_token_at_offset(T![+])?;
+    // Make sure we're in a `TypeBoundList`
+    if ast::TypeBoundList::cast(plus.parent()).is_none() {
+        return None;
+    }
+    let (before, after) = (
+        non_trivia_sibling(plus.clone().into(), Direction::Prev)?,
+        non_trivia_sibling(plus.clone().into(), Direction::Next)?,
+    );
+    ctx.add_assist(AssistId("flip_trait_bound"), "flip trait bound", |edit| {
+        edit.target(plus.text_range());
+        edit.replace(before.text_range(), after.to_string());
+        edit.replace(after.text_range(), before.to_string());
+    })
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+    #[test]
+    fn flip_trait_bound_assist_available() {
+        check_assist_target(flip_trait_bound, "struct S<T> where T: A <|>+ B + C { }", "+")
+    }
+    #[test]
+    fn flip_trait_bound_not_applicable_for_single_trait_bound() {
+        check_assist_not_applicable(flip_trait_bound, "struct S<T> where T: <|>A { }")
+    }
+    #[test]
+    fn flip_trait_bound_works_for_struct() {
+        check_assist(
+            flip_trait_bound,
+            "struct S<T> where T: A <|>+ B { }",
+            "struct S<T> where T: B <|>+ A { }",
+        )
+    }
+    #[test]
+    fn flip_trait_bound_works_for_trait_impl() {
+        check_assist(
+            flip_trait_bound,
+            "impl X for S<T> where T: A +<|> B { }",
+            "impl X for S<T> where T: B +<|> A { }",
+        )
+    }
+    #[test]
+    fn flip_trait_bound_works_for_fn() {
+        check_assist(flip_trait_bound, "fn f<T: A <|>+ B>(t: T) { }", "fn f<T: B <|>+ A>(t: T) { }")
+    }
+    #[test]
+    fn flip_trait_bound_works_for_fn_where_clause() {
+        check_assist(
+            flip_trait_bound,
+            "fn f<T>(t: T) where T: A +<|> B { }",
+            "fn f<T>(t: T) where T: B +<|> A { }",
+        )
+    }
+    #[test]
+    fn flip_trait_bound_works_for_lifetime() {
+        check_assist(
+            flip_trait_bound,
+            "fn f<T>(t: T) where T: A <|>+ 'static { }",
+            "fn f<T>(t: T) where T: 'static <|>+ A { }",
+        )
+    }
+    #[test]
+    fn flip_trait_bound_works_for_complex_bounds() {
+        check_assist(
+            flip_trait_bound,
+            "struct S<T> where T: A<T> <|>+ b_mod::B<T> + C<T> { }",
+            "struct S<T> where T: b_mod::B<T> <|>+ A<T> + C<T> { }",
+        )
+    }
+    #[test]
+    fn flip_trait_bound_works_for_long_bounds() {
+        check_assist(
+            flip_trait_bound,
+            "struct S<T> where T: A + B + C + D + E + F +<|> G + H + I + J { }",
+            "struct S<T> where T: A + B + C + D + E + G +<|> F + H + I + J { }",
+        )
+    }
+}
diff --git a/crates/ra_assists/src/assists/inline_local_variable.rs b/crates/ra_assists/src/assists/inline_local_variable.rs
index 9bd64decc..a7fd9b6d2 100644
--- a/crates/ra_assists/src/assists/inline_local_variable.rs
+++ b/crates/ra_assists/src/assists/inline_local_variable.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast::{self, AstNode, AstToken},
@@ -9,8 +7,24 @@ use ra_syntax::{
 use crate::assist_ctx::AssistBuilder;
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn inline_local_varialbe(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: inline_local_variable
-    let let_stmt = ctx.node_at_offset::<ast::LetStmt>()?;
+//
+// Inlines local variable.
+//
+// ```
+// fn main() {
+//     let x<|> = 1 + 2;
+//     x * 4;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     (1 + 2) * 4;
+// }
+// ```
+pub(crate) fn inline_local_varialbe(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let let_stmt = ctx.find_node_at_offset::<ast::LetStmt>()?;
    let bind_pat = match let_stmt.pat()? {
        ast::Pat::BindPat(pat) => pat,
        _ => return None,
@@ -37,10 +51,8 @@ pub(crate) fn inline_local_varialbe(mut ctx: AssistCtx<impl HirDatabase>) -> Opt
    let mut wrap_in_parens = vec![true; refs.len()];
    for (i, desc) in refs.iter().enumerate() {
-        let usage_node = ctx
+        let usage_node =
-            .covering_node_for_range(desc.range)
+            ctx.covering_node_for_range(desc.range).ancestors().find_map(ast::PathExpr::cast)?;
-            .ancestors()
-            .find_map(|node| ast::PathExpr::cast(node))?;
        let usage_parent_option = usage_node.syntax().parent().and_then(ast::Expr::cast);
        let usage_parent = match usage_parent_option {
            Some(u) => u,
@@ -79,7 +91,7 @@ pub(crate) fn inline_local_varialbe(mut ctx: AssistCtx<impl HirDatabase>) -> Opt
    let init_str = initializer_expr.syntax().text().to_string();
    let init_in_paren = format!("({})", &init_str);
-    ctx.add_action(
+    ctx.add_assist(
        AssistId("inline_local_variable"),
        "inline local variable",
        move |edit: &mut AssistBuilder| {
@@ -93,9 +105,7 @@ pub(crate) fn inline_local_varialbe(mut ctx: AssistCtx<impl HirDatabase>) -> Opt
            }
            edit.set_cursor(delete_range.start())
        },
-    );
+    )
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/introduce_variable.rs b/crates/ra_assists/src/assists/introduce_variable.rs
index 43378c4b0..0623d4475 100644
--- a/crates/ra_assists/src/assists/introduce_variable.rs
+++ b/crates/ra_assists/src/assists/introduce_variable.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use format_buf::format;
 use hir::db::HirDatabase;
 use ra_syntax::{
@@ -14,7 +12,23 @@ use test_utils::tested_by;
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn introduce_variable(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: introduce_variable
+//
+// Extracts subexpression into a variable.
+//
+// ```
+// fn main() {
+//     <|>(1 + 2)<|> * 4;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let var_name = (1 + 2);
+//     var_name * 4;
+// }
+// ```
+pub(crate) fn introduce_variable(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
    if ctx.frange.range.is_empty() {
        return None;
    }
@@ -29,7 +43,7 @@ pub(crate) fn introduce_variable(mut ctx: AssistCtx<impl HirDatabase>) -> Option
    if indent.kind() != WHITESPACE {
        return None;
    }
-    ctx.add_action(AssistId("introduce_variable"), "introduce variable", move |edit| {
+    ctx.add_assist(AssistId("introduce_variable"), "introduce variable", move |edit| {
        let mut buf = String::new();
        let cursor_offset = if wrap_in_block {
@@ -74,9 +88,7 @@ pub(crate) fn introduce_variable(mut ctx: AssistCtx<impl HirDatabase>) -> Option
            }
        }
        edit.set_cursor(anchor_stmt.text_range().start() + cursor_offset);
-    });
+    })
-    ctx.build()
 }
 /// Check whether the node is a valid expression which can be extracted to a variable.
diff --git a/crates/ra_assists/src/assists/merge_match_arms.rs b/crates/ra_assists/src/assists/merge_match_arms.rs
index 17baa98f9..e9f2cae91 100644
--- a/crates/ra_assists/src/assists/merge_match_arms.rs
+++ b/crates/ra_assists/src/assists/merge_match_arms.rs
@@ -1,11 +1,33 @@
-//! FIXME: write short doc here
 use crate::{Assist, AssistCtx, AssistId, TextRange, TextUnit};
 use hir::db::HirDatabase;
 use ra_syntax::ast::{AstNode, MatchArm};
-pub(crate) fn merge_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: merge_match_arms
-    let current_arm = ctx.node_at_offset::<MatchArm>()?;
+//
+// Merges identical match arms.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         <|>Action::Move(..) => foo(),
+//         Action::Stop => foo(),
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move(..) | Action::Stop => foo(),
+//     }
+// }
+// ```
+pub(crate) fn merge_match_arms(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let current_arm = ctx.find_node_at_offset::<MatchArm>()?;
    // We check if the following match arm matches this one. We could, but don't,
    // compare to the previous match arm as well.
@@ -30,7 +52,7 @@ pub(crate) fn merge_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<A
    let cursor_to_end = current_arm.syntax().text_range().end() - ctx.frange.range.start();
-    ctx.add_action(AssistId("merge_match_arms"), "merge match arms", |edit| {
+    ctx.add_assist(AssistId("merge_match_arms"), "merge match arms", |edit| {
        fn contains_placeholder(a: &MatchArm) -> bool {
            a.pats().any(|x| match x {
                ra_syntax::ast::Pat::PlaceholderPat(..) => true,
@@ -58,9 +80,7 @@ pub(crate) fn merge_match_arms(mut ctx: AssistCtx<impl HirDatabase>) -> Option<A
        edit.target(current_arm.syntax().text_range());
        edit.replace(TextRange::from_to(start, end), arm);
        edit.set_cursor(start + offset);
-    });
+    })
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/move_bounds.rs b/crates/ra_assists/src/assists/move_bounds.rs
index d2444b6b9..3145d7625 100644
--- a/crates/ra_assists/src/assists/move_bounds.rs
+++ b/crates/ra_assists/src/assists/move_bounds.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast::{self, edit, make, AstNode, NameOwner, TypeBoundsOwner},
@@ -9,8 +7,23 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn move_bounds_to_where_clause(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: move_bounds_to_where_clause
-    let type_param_list = ctx.node_at_offset::<ast::TypeParamList>()?;
+//
+// Moves inline type bounds to a where clause.
+//
+// ```
+// fn apply<T, U, <|>F: FnOnce(T) -> U>(f: F, x: T) -> U {
+//     f(x)
+// }
+// ```
+// ->
+// ```
+// fn apply<T, U, F>(f: F, x: T) -> U where F: FnOnce(T) -> U {
+//     f(x)
+// }
+// ```
+pub(crate) fn move_bounds_to_where_clause(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let type_param_list = ctx.find_node_at_offset::<ast::TypeParamList>()?;
    let mut type_params = type_param_list.type_params();
    if type_params.all(|p| p.type_bound_list().is_none()) {
@@ -33,38 +46,30 @@ pub(crate) fn move_bounds_to_where_clause(mut ctx: AssistCtx<impl HirDatabase>)
        _ => return None,
    };
-    ctx.add_action(
+    ctx.add_assist(AssistId("move_bounds_to_where_clause"), "move_bounds_to_where_clause", |edit| {
-        AssistId("move_bounds_to_where_clause"),
+        let new_params = type_param_list
-        "move_bounds_to_where_clause",
+            .type_params()
-        |edit| {
+            .filter(|it| it.type_bound_list().is_some())
-            let new_params = type_param_list
+            .map(|type_param| {
-                .type_params()
+                let without_bounds = type_param.remove_bounds();
-                .filter(|it| it.type_bound_list().is_some())
+                (type_param, without_bounds)
-                .map(|type_param| {
+            });
-                    let without_bounds = type_param.remove_bounds();
-                    (type_param, without_bounds)
+        let new_type_param_list = edit::replace_descendants(&type_param_list, new_params);
-                });
+        edit.replace_ast(type_param_list.clone(), new_type_param_list);
-            let new_type_param_list = edit::replace_descendants(&type_param_list, new_params);
+        let where_clause = {
-            edit.replace_ast(type_param_list.clone(), new_type_param_list);
+            let predicates = type_param_list.type_params().filter_map(build_predicate);
+            make::where_clause(predicates)
-            let where_clause = {
+        };
-                let predicates = type_param_list.type_params().filter_map(build_predicate);
-                make::where_clause(predicates)
+        let to_insert = match anchor.prev_sibling_or_token() {
-            };
+            Some(ref elem) if elem.kind() == WHITESPACE => format!("{} ", where_clause.syntax()),
+            _ => format!(" {}", where_clause.syntax()),
-            let to_insert = match anchor.prev_sibling_or_token() {
+        };
-                Some(ref elem) if elem.kind() == WHITESPACE => {
+        edit.insert(anchor.text_range().start(), to_insert);
-                    format!("{} ", where_clause.syntax())
+        edit.target(type_param_list.syntax().text_range());
-                }
+    })
-                _ => format!(" {}", where_clause.syntax()),
-            };
-            edit.insert(anchor.text_range().start(), to_insert);
-            edit.target(type_param_list.syntax().text_range());
-        },
-    );
-    ctx.build()
 }
 fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
diff --git a/crates/ra_assists/src/assists/move_guard.rs b/crates/ra_assists/src/assists/move_guard.rs
index 51aea6334..b49ec6172 100644
--- a/crates/ra_assists/src/assists/move_guard.rs
+++ b/crates/ra_assists/src/assists/move_guard.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast,
@@ -9,8 +7,33 @@ use ra_syntax::{
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn move_guard_to_arm_body(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: move_guard_to_arm_body
-    let match_arm = ctx.node_at_offset::<MatchArm>()?;
+//
+// Moves match guard into match arm body.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } <|>if distance > 10 => foo(),
+//         _ => (),
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } => if distance > 10 { foo() },
+//         _ => (),
+//     }
+// }
+// ```
+pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let match_arm = ctx.find_node_at_offset::<MatchArm>()?;
    let guard = match_arm.guard()?;
    let space_before_guard = guard.syntax().prev_sibling_or_token();
@@ -18,7 +41,7 @@ pub(crate) fn move_guard_to_arm_body(mut ctx: AssistCtx<impl HirDatabase>) -> Op
    let arm_expr = match_arm.expr()?;
    let buf = format!("if {} {{ {} }}", guard_conditions.syntax().text(), arm_expr.syntax().text());
-    ctx.add_action(AssistId("move_guard_to_arm_body"), "move guard to arm body", |edit| {
+    ctx.add_assist(AssistId("move_guard_to_arm_body"), "move guard to arm body", |edit| {
        edit.target(guard.syntax().text_range());
        let offseting_amount = match space_before_guard.and_then(|it| it.into_token()) {
            Some(tok) => {
@@ -38,12 +61,36 @@ pub(crate) fn move_guard_to_arm_body(mut ctx: AssistCtx<impl HirDatabase>) -> Op
        edit.set_cursor(
            arm_expr.syntax().text_range().start() + TextUnit::from(3) - offseting_amount,
        );
-    });
+    })
-    ctx.build()
 }
-pub(crate) fn move_arm_cond_to_match_guard(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: move_arm_cond_to_match_guard
-    let match_arm: MatchArm = ctx.node_at_offset::<MatchArm>()?;
+//
+// Moves if expression from match arm body into a guard.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } => <|>if distance > 10 { foo() },
+//         _ => (),
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } if distance > 10 => foo(),
+//         _ => (),
+//     }
+// }
+// ```
+pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let match_arm: MatchArm = ctx.find_node_at_offset::<MatchArm>()?;
    let last_match_pat = match_arm.pats().last()?;
    let arm_body = match_arm.expr()?;
@@ -62,7 +109,7 @@ pub(crate) fn move_arm_cond_to_match_guard(mut ctx: AssistCtx<impl HirDatabase>)
    let buf = format!(" if {}", cond.syntax().text());
-    ctx.add_action(
+    ctx.add_assist(
        AssistId("move_arm_cond_to_match_guard"),
        "move condition to match guard",
        |edit| {
@@ -79,8 +126,7 @@ pub(crate) fn move_arm_cond_to_match_guard(mut ctx: AssistCtx<impl HirDatabase>)
            edit.insert(last_match_pat.syntax().text_range().end(), buf);
            edit.set_cursor(last_match_pat.syntax().text_range().end() + TextUnit::from(1));
        },
-    );
+    )
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/assists/raw_string.rs b/crates/ra_assists/src/assists/raw_string.rs
index 2d2e31e51..58f7157ae 100644
--- a/crates/ra_assists/src/assists/raw_string.rs
+++ b/crates/ra_assists/src/assists/raw_string.rs
@@ -1,17 +1,29 @@
-//! FIXME: write short doc here
 use hir::db::HirDatabase;
-use ra_syntax::{ast::AstNode, ast::Literal, TextRange, TextUnit};
+use ra_syntax::{
+    SyntaxKind::{RAW_STRING, STRING},
+    TextRange, TextUnit,
+};
 use rustc_lexer;
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn make_raw_string(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: make_raw_string
-    let literal = ctx.node_at_offset::<Literal>()?;
+//
-    if literal.token().kind() != ra_syntax::SyntaxKind::STRING {
+// Adds `r#` to a plain string literal.
-        return None;
+//
-    }
+// ```
-    let token = literal.token();
+// fn main() {
+//     "Hello,<|> World!";
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     r#"Hello, World!"#;
+// }
+// ```
+pub(crate) fn make_raw_string(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let token = ctx.find_token_at_offset(STRING)?;
    let text = token.text().as_str();
    let usual_string_range = find_usual_string_range(text)?;
    let start_of_inside = usual_string_range.start().to_usize() + 1;
@@ -29,97 +41,131 @@ pub(crate) fn make_raw_string(mut ctx: AssistCtx<impl HirDatabase>) -> Option<As
    if error.is_err() {
        return None;
    }
-    ctx.add_action(AssistId("make_raw_string"), "make raw string", |edit| {
+    ctx.add_assist(AssistId("make_raw_string"), "make raw string", |edit| {
-        edit.target(literal.syntax().text_range());
+        edit.target(token.text_range());
        let max_hash_streak = count_hashes(&unescaped);
        let mut hashes = String::with_capacity(max_hash_streak + 1);
        for _ in 0..hashes.capacity() {
            hashes.push('#');
        }
-        edit.replace(
+        edit.replace(token.text_range(), format!("r{}\"{}\"{}", hashes, unescaped, hashes));
-            literal.syntax().text_range(),
+    })
-            format!("r{}\"{}\"{}", hashes, unescaped, hashes),
-        );
-    });
-    ctx.build()
-}
-fn count_hashes(s: &str) -> usize {
-    let mut max_hash_streak = 0usize;
-    for idx in s.match_indices("\"#").map(|(i, _)| i) {
-        let (_, sub) = s.split_at(idx + 1);
-        let nb_hash = sub.chars().take_while(|c| *c == '#').count();
-        if nb_hash > max_hash_streak {
-            max_hash_streak = nb_hash;
-        }
-    }
-    max_hash_streak
-}
-fn find_usual_string_range(s: &str) -> Option<TextRange> {
-    Some(TextRange::from_to(
-        TextUnit::from(s.find('"')? as u32),
-        TextUnit::from(s.rfind('"')? as u32),
-    ))
 }
-pub(crate) fn make_usual_string(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: make_usual_string
-    let literal = ctx.node_at_offset::<Literal>()?;
+//
-    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
+// Turns a raw string into a plain string.
-        return None;
+//
-    }
+// ```
-    let token = literal.token();
+// fn main() {
+//     r#"Hello,<|> "World!""#;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     "Hello, \"World!\"";
+// }
+// ```
+pub(crate) fn make_usual_string(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let token = ctx.find_token_at_offset(RAW_STRING)?;
    let text = token.text().as_str();
    let usual_string_range = find_usual_string_range(text)?;
-    ctx.add_action(AssistId("make_usual_string"), "make usual string", |edit| {
+    ctx.add_assist(AssistId("make_usual_string"), "make usual string", |edit| {
-        edit.target(literal.syntax().text_range());
+        edit.target(token.text_range());
        // parse inside string to escape `"`
        let start_of_inside = usual_string_range.start().to_usize() + 1;
        let end_of_inside = usual_string_range.end().to_usize();
        let inside_str = &text[start_of_inside..end_of_inside];
        let escaped = inside_str.escape_default().to_string();
-        edit.replace(literal.syntax().text_range(), format!("\"{}\"", escaped));
+        edit.replace(token.text_range(), format!("\"{}\"", escaped));
-    });
+    })
-    ctx.build()
 }
-pub(crate) fn add_hash(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: add_hash
-    let literal = ctx.node_at_offset::<Literal>()?;
+//
-    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
+// Adds a hash to a raw string literal.
-        return None;
+//
-    }
+// ```
-    ctx.add_action(AssistId("add_hash"), "add hash to raw string", |edit| {
+// fn main() {
-        edit.target(literal.syntax().text_range());
+//     r#"Hello,<|> World!"#;
-        edit.insert(literal.syntax().text_range().start() + TextUnit::of_char('r'), "#");
+// }
-        edit.insert(literal.syntax().text_range().end(), "#");
+// ```
-    });
+// ->
-    ctx.build()
+// ```
+// fn main() {
+//     r##"Hello, World!"##;
+// }
+// ```
+pub(crate) fn add_hash(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let token = ctx.find_token_at_offset(RAW_STRING)?;
+    ctx.add_assist(AssistId("add_hash"), "add hash to raw string", |edit| {
+        edit.target(token.text_range());
+        edit.insert(token.text_range().start() + TextUnit::of_char('r'), "#");
+        edit.insert(token.text_range().end(), "#");
+    })
 }
-pub(crate) fn remove_hash(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: remove_hash
-    let literal = ctx.node_at_offset::<Literal>()?;
+//
-    if literal.token().kind() != ra_syntax::SyntaxKind::RAW_STRING {
+// Removes a hash from a raw string literal.
-        return None;
+//
-    }
+// ```
-    let token = literal.token();
+// fn main() {
+//     r#"Hello,<|> World!"#;
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     r"Hello, World!";
+// }
+// ```
+pub(crate) fn remove_hash(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let token = ctx.find_token_at_offset(RAW_STRING)?;
    let text = token.text().as_str();
    if text.starts_with("r\"") {
        // no hash to remove
        return None;
    }
-    ctx.add_action(AssistId("remove_hash"), "remove hash from raw string", |edit| {
+    ctx.add_assist(AssistId("remove_hash"), "remove hash from raw string", |edit| {
-        edit.target(literal.syntax().text_range());
+        edit.target(token.text_range());
        let result = &text[2..text.len() - 1];
-        let result = if result.starts_with("\"") {
+        let result = if result.starts_with('\"') {
            // no more hash, escape
            let internal_str = &result[1..result.len() - 1];
            format!("\"{}\"", internal_str.escape_default().to_string())
        } else {
            result.to_owned()
        };
-        edit.replace(literal.syntax().text_range(), format!("r{}", result));
+        edit.replace(token.text_range(), format!("r{}", result));
-    });
+    })
-    ctx.build()
+}
+fn count_hashes(s: &str) -> usize {
+    let mut max_hash_streak = 0usize;
+    for idx in s.match_indices("\"#").map(|(i, _)| i) {
+        let (_, sub) = s.split_at(idx + 1);
+        let nb_hash = sub.chars().take_while(|c| *c == '#').count();
+        if nb_hash > max_hash_streak {
+            max_hash_streak = nb_hash;
+        }
+    }
+    max_hash_streak
+}
+fn find_usual_string_range(s: &str) -> Option<TextRange> {
+    let left_quote = s.find('"')?;
+    let right_quote = s.rfind('"')?;
+    if left_quote == right_quote {
+        // `s` only contains one quote
+        None
+    } else {
+        Some(TextRange::from_to(
+            TextUnit::from(left_quote as u32),
+            TextUnit::from(right_quote as u32),
+        ))
+    }
 }
 #[cfg(test)]
@@ -159,6 +205,23 @@ string"#;
    }
    #[test]
+    fn make_raw_string_works_inside_macros() {
+        check_assist(
+            make_raw_string,
+            r#"
+            fn f() {
+                format!(<|>"x = {}", 92)
+            }
+            "#,
+            r##"
+            fn f() {
+                format!(<|>r#"x = {}"#, 92)
+            }
+            "##,
+        )
+    }
+    #[test]
    fn make_raw_string_hashes_inside_works() {
        check_assist(
            make_raw_string,
@@ -212,6 +275,30 @@ string"###;
    }
    #[test]
+    fn make_raw_string_not_works_on_partial_string() {
+        check_assist_not_applicable(
+            make_raw_string,
+            r#"
+            fn f() {
+                let s = "foo<|>
+            }
+            "#,
+        )
+    }
+    #[test]
+    fn make_usual_string_not_works_on_partial_string() {
+        check_assist_not_applicable(
+            make_usual_string,
+            r#"
+            fn main() {
+                let s = r#"bar<|>
+            }
+            "#,
+        )
+    }
+    #[test]
    fn add_hash_target() {
        check_assist_target(
            add_hash,
diff --git a/crates/ra_assists/src/assists/remove_dbg.rs b/crates/ra_assists/src/assists/remove_dbg.rs
index 1a7e2b305..aedf8747f 100644
--- a/crates/ra_assists/src/assists/remove_dbg.rs
+++ b/crates/ra_assists/src/assists/remove_dbg.rs
@@ -1,14 +1,28 @@
-//! FIXME: write short doc here
-use crate::{Assist, AssistCtx, AssistId};
 use hir::db::HirDatabase;
 use ra_syntax::{
    ast::{self, AstNode},
    TextUnit, T,
 };
-pub(crate) fn remove_dbg(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+use crate::{Assist, AssistCtx, AssistId};
-    let macro_call = ctx.node_at_offset::<ast::MacroCall>()?;
+// Assist: remove_dbg
+//
+// Removes `dbg!()` macro call.
+//
+// ```
+// fn main() {
+//     <|>dbg!(92);
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     92;
+// }
+// ```
+pub(crate) fn remove_dbg(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let macro_call = ctx.find_node_at_offset::<ast::MacroCall>()?;
    if !is_valid_macrocall(&macro_call, "dbg")? {
        return None;
@@ -44,13 +58,11 @@ pub(crate) fn remove_dbg(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist>
        text.slice(without_parens).to_string()
    };
-    ctx.add_action(AssistId("remove_dbg"), "remove dbg!()", |edit| {
+    ctx.add_assist(AssistId("remove_dbg"), "remove dbg!()", |edit| {
        edit.target(macro_call.syntax().text_range());
        edit.replace(macro_range, macro_content);
        edit.set_cursor(cursor_pos);
-    });
+    })
-    ctx.build()
 }
 /// Verifies that the given macro_call actually matches the given name
diff --git a/crates/ra_assists/src/assists/replace_if_let_with_match.rs b/crates/ra_assists/src/assists/replace_if_let_with_match.rs
index 749ff338a..dff84d865 100644
--- a/crates/ra_assists/src/assists/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/assists/replace_if_let_with_match.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use format_buf::format;
 use hir::db::HirDatabase;
 use ra_fmt::extract_trivial_expression;
@@ -7,8 +5,34 @@ use ra_syntax::{ast, AstNode};
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn replace_if_let_with_match(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: replace_if_let_with_match
-    let if_expr: ast::IfExpr = ctx.node_at_offset()?;
+//
+// Replaces `if let` with an else branch with a `match` expression.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     <|>if let Action::Move { distance } = action {
+//         foo(distance)
+//     } else {
+//         bar()
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } => foo(distance),
+//         _ => bar(),
+//     }
+// }
+// ```
+pub(crate) fn replace_if_let_with_match(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
    let cond = if_expr.condition()?;
    let pat = cond.pat()?;
    let expr = cond.expr()?;
@@ -18,14 +42,12 @@ pub(crate) fn replace_if_let_with_match(mut ctx: AssistCtx<impl HirDatabase>) ->
        ast::ElseBranch::IfExpr(_) => return None,
    };
-    ctx.add_action(AssistId("replace_if_let_with_match"), "replace with match", |edit| {
+    ctx.add_assist(AssistId("replace_if_let_with_match"), "replace with match", |edit| {
        let match_expr = build_match_expr(expr, pat, then_block, else_block);
        edit.target(if_expr.syntax().text_range());
        edit.replace_node_and_indent(if_expr.syntax(), match_expr);
        edit.set_cursor(if_expr.syntax().text_range().start())
-    });
+    })
-    ctx.build()
 }
 fn build_match_expr(
diff --git a/crates/ra_assists/src/assists/split_import.rs b/crates/ra_assists/src/assists/split_import.rs
index fe3e64af5..5f8d6b0be 100644
--- a/crates/ra_assists/src/assists/split_import.rs
+++ b/crates/ra_assists/src/assists/split_import.rs
@@ -1,5 +1,3 @@
-//! FIXME: write short doc here
 use std::iter::successors;
 use hir::db::HirDatabase;
@@ -7,8 +5,19 @@ use ra_syntax::{ast, AstNode, TextUnit, T};
 use crate::{Assist, AssistCtx, AssistId};
-pub(crate) fn split_import(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+// Assist: split_import
-    let colon_colon = ctx.token_at_offset().find(|leaf| leaf.kind() == T![::])?;
+//
+// Wraps the tail of import into braces.
+//
+// ```
+// use std::<|>collections::HashMap;
+// ```
+// ->
+// ```
+// use std::{collections::HashMap};
+// ```
+pub(crate) fn split_import(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let colon_colon = ctx.find_token_at_offset(T![::])?;
    let path = ast::Path::cast(colon_colon.parent())?;
    let top_path = successors(Some(path), |it| it.parent_path()).last()?;
@@ -23,14 +32,12 @@ pub(crate) fn split_import(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assis
        None => top_path.syntax().text_range().end(),
    };
-    ctx.add_action(AssistId("split_import"), "split import", |edit| {
+    ctx.add_assist(AssistId("split_import"), "split import", |edit| {
        edit.target(colon_colon.text_range());
        edit.insert(l_curly, "{");
        edit.insert(r_curly, "}");
        edit.set_cursor(l_curly + TextUnit::of_str("{"));
-    });
+    })
-    ctx.build()
 }
 #[cfg(test)]
diff --git a/crates/ra_assists/src/doc_tests.rs b/crates/ra_assists/src/doc_tests.rs
new file mode 100644
index 000000000..6e1e3de84
--- /dev/null
+++ b/crates/ra_assists/src/doc_tests.rs
@@ -0,0 +1,34 @@
+//! Each assist definition has a special comment, which specifies docs and
+//! example.
+//!
+//! We collect all the example and write the as tests in this module.
+mod generated;
+use hir::mock::MockDatabase;
+use ra_db::FileRange;
+use test_utils::{assert_eq_text, extract_range_or_offset};
+fn check(assist_id: &str, before: &str, after: &str) {
+    let (selection, before) = extract_range_or_offset(before);
+    let (db, _source_root, file_id) = MockDatabase::with_single_file(&before);
+    let frange = FileRange { file_id, range: selection.into() };
+    let (_assist_id, action) = crate::assists(&db, frange)
+        .into_iter()
+        .find(|(id, _)| id.id.0 == assist_id)
+        .unwrap_or_else(|| {
+            panic!(
+                "\n\nAssist is not applicable: {}\nAvailable assists: {}",
+                assist_id,
+                crate::assists(&db, frange)
+                    .into_iter()
+                    .map(|(id, _)| id.id.0)
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            )
+        });
+    let actual = action.edit.apply(&before);
+    assert_eq_text!(after, &actual);
+}
diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
new file mode 100644
index 000000000..1bee76f59
--- /dev/null
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -0,0 +1,526 @@
+//! Generated file, do not edit by hand, see `crate/ra_tools/src/codegen`
+use super::check;
+#[test]
+fn doctest_add_derive() {
+    check(
+        "add_derive",
+        r#####"
+struct Point {
+    x: u32,
+    y: u32,<|>
+}
+"#####,
+        r#####"
+#[derive()]
+struct Point {
+    x: u32,
+    y: u32,
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_explicit_type() {
+    check(
+        "add_explicit_type",
+        r#####"
+fn main() {
+    let x<|> = 92;
+}
+"#####,
+        r#####"
+fn main() {
+    let x: i32 = 92;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_hash() {
+    check(
+        "add_hash",
+        r#####"
+fn main() {
+    r#"Hello,<|> World!"#;
+}
+"#####,
+        r#####"
+fn main() {
+    r##"Hello, World!"##;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_impl() {
+    check(
+        "add_impl",
+        r#####"
+struct Ctx<T: Clone> {
+     data: T,<|>
+}
+"#####,
+        r#####"
+struct Ctx<T: Clone> {
+     data: T,
+}
+impl<T: Clone> Ctx<T> {
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_impl_default_members() {
+    check(
+        "add_impl_default_members",
+        r#####"
+trait T {
+    Type X;
+    fn foo(&self);
+    fn bar(&self) {}
+}
+impl T for () {
+    Type X = ();
+    fn foo(&self) {}<|>
+}
+"#####,
+        r#####"
+trait T {
+    Type X;
+    fn foo(&self);
+    fn bar(&self) {}
+}
+impl T for () {
+    Type X = ();
+    fn foo(&self) {}
+    fn bar(&self) {}
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_impl_missing_members() {
+    check(
+        "add_impl_missing_members",
+        r#####"
+trait T {
+    Type X;
+    fn foo(&self);
+    fn bar(&self) {}
+}
+impl T for () {<|>
+}
+"#####,
+        r#####"
+trait T {
+    Type X;
+    fn foo(&self);
+    fn bar(&self) {}
+}
+impl T for () {
+    fn foo(&self) { unimplemented!() }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_add_import() {
+    check(
+        "add_import",
+        r#####"
+fn process(map: std::collections::<|>HashMap<String, String>) {}
+"#####,
+        r#####"
+use std::collections::HashMap;
+fn process(map: HashMap<String, String>) {}
+"#####,
+    )
+}
+#[test]
+fn doctest_apply_demorgan() {
+    check(
+        "apply_demorgan",
+        r#####"
+fn main() {
+    if x != 4 ||<|> !y {}
+}
+"#####,
+        r#####"
+fn main() {
+    if !(x == 4 && y) {}
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_change_visibility() {
+    check(
+        "change_visibility",
+        r#####"
+<|>fn frobnicate() {}
+"#####,
+        r#####"
+pub(crate) fn frobnicate() {}
+"#####,
+    )
+}
+#[test]
+fn doctest_convert_to_guarded_return() {
+    check(
+        "convert_to_guarded_return",
+        r#####"
+fn main() {
+    <|>if cond {
+        foo();
+        bar();
+    }
+}
+"#####,
+        r#####"
+fn main() {
+    if !cond {
+        return;
+    }
+    foo();
+    bar();
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_fill_match_arms() {
+    check(
+        "fill_match_arms",
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        <|>
+    }
+}
+"#####,
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } => (),
+        Action::Stop => (),
+    }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_flip_binexpr() {
+    check(
+        "flip_binexpr",
+        r#####"
+fn main() {
+    let _ = 90 +<|> 2;
+}
+"#####,
+        r#####"
+fn main() {
+    let _ = 2 + 90;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_flip_comma() {
+    check(
+        "flip_comma",
+        r#####"
+fn main() {
+    ((1, 2),<|> (3, 4));
+}
+"#####,
+        r#####"
+fn main() {
+    ((3, 4), (1, 2));
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_flip_trait_bound() {
+    check(
+        "flip_trait_bound",
+        r#####"
+fn foo<T: Clone +<|> Copy>() { }
+"#####,
+        r#####"
+fn foo<T: Copy + Clone>() { }
+"#####,
+    )
+}
+#[test]
+fn doctest_inline_local_variable() {
+    check(
+        "inline_local_variable",
+        r#####"
+fn main() {
+    let x<|> = 1 + 2;
+    x * 4;
+}
+"#####,
+        r#####"
+fn main() {
+    (1 + 2) * 4;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_introduce_variable() {
+    check(
+        "introduce_variable",
+        r#####"
+fn main() {
+    <|>(1 + 2)<|> * 4;
+}
+"#####,
+        r#####"
+fn main() {
+    let var_name = (1 + 2);
+    var_name * 4;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_make_raw_string() {
+    check(
+        "make_raw_string",
+        r#####"
+fn main() {
+    "Hello,<|> World!";
+}
+"#####,
+        r#####"
+fn main() {
+    r#"Hello, World!"#;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_make_usual_string() {
+    check(
+        "make_usual_string",
+        r#####"
+fn main() {
+    r#"Hello,<|> "World!""#;
+}
+"#####,
+        r#####"
+fn main() {
+    "Hello, \"World!\"";
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_merge_match_arms() {
+    check(
+        "merge_match_arms",
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        <|>Action::Move(..) => foo(),
+        Action::Stop => foo(),
+    }
+}
+"#####,
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move(..) | Action::Stop => foo(),
+    }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_move_arm_cond_to_match_guard() {
+    check(
+        "move_arm_cond_to_match_guard",
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } => <|>if distance > 10 { foo() },
+        _ => (),
+    }
+}
+"#####,
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } if distance > 10 => foo(),
+        _ => (),
+    }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_move_bounds_to_where_clause() {
+    check(
+        "move_bounds_to_where_clause",
+        r#####"
+fn apply<T, U, <|>F: FnOnce(T) -> U>(f: F, x: T) -> U {
+    f(x)
+}
+"#####,
+        r#####"
+fn apply<T, U, F>(f: F, x: T) -> U where F: FnOnce(T) -> U {
+    f(x)
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_move_guard_to_arm_body() {
+    check(
+        "move_guard_to_arm_body",
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } <|>if distance > 10 => foo(),
+        _ => (),
+    }
+}
+"#####,
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } => if distance > 10 { foo() },
+        _ => (),
+    }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_remove_dbg() {
+    check(
+        "remove_dbg",
+        r#####"
+fn main() {
+    <|>dbg!(92);
+}
+"#####,
+        r#####"
+fn main() {
+    92;
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_remove_hash() {
+    check(
+        "remove_hash",
+        r#####"
+fn main() {
+    r#"Hello,<|> World!"#;
+}
+"#####,
+        r#####"
+fn main() {
+    r"Hello, World!";
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_replace_if_let_with_match() {
+    check(
+        "replace_if_let_with_match",
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    <|>if let Action::Move { distance } = action {
+        foo(distance)
+    } else {
+        bar()
+    }
+}
+"#####,
+        r#####"
+enum Action { Move { distance: u32 }, Stop }
+fn handle(action: Action) {
+    match action {
+        Action::Move { distance } => foo(distance),
+        _ => bar(),
+    }
+}
+"#####,
+    )
+}
+#[test]
+fn doctest_split_import() {
+    check(
+        "split_import",
+        r#####"
+use std::<|>collections::HashMap;
+"#####,
+        r#####"
+use std::{collections::HashMap};
+"#####,
+    )
+}
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index ab77b46a9..38599d4f1 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -7,15 +7,16 @@
 mod assist_ctx;
 mod marks;
+#[cfg(test)]
+mod doc_tests;
 use hir::db::HirDatabase;
-use itertools::Itertools;
 use ra_db::FileRange;
 use ra_syntax::{TextRange, TextUnit};
 use ra_text_edit::TextEdit;
 pub(crate) use crate::assist_ctx::{Assist, AssistCtx};
-pub use crate::assists::auto_import::auto_import_text_edit;
+pub use crate::assists::add_import::auto_import_text_edit;
 /// Unique identifier of the assist, should not be shown to the user
 /// directly.
@@ -36,7 +37,7 @@ pub struct AssistAction {
    pub target: Option<TextRange>,
 }
-/// Return all the assists eapplicable at the given position.
+/// Return all the assists applicable at the given position.
 ///
 /// Assists are returned in the "unresolved" state, that is only labels are
 /// returned, without actual edits.
@@ -49,10 +50,10 @@ where
            .iter()
            .filter_map(|f| f(ctx.clone()))
            .map(|a| match a {
-                Assist::Unresolved(labels) => labels,
+                Assist::Unresolved { label } => label,
-                Assist::Resolved(..) => unreachable!(),
+                Assist::Resolved { .. } => unreachable!(),
            })
-            .concat()
+            .collect()
    })
 }
@@ -71,10 +72,10 @@ where
            .iter()
            .filter_map(|f| f(ctx.clone()))
            .map(|a| match a {
-                Assist::Resolved(labels_actions) => labels_actions,
+                Assist::Resolved { label, action } => (label, action),
-                Assist::Unresolved(..) => unreachable!(),
+                Assist::Unresolved { .. } => unreachable!(),
            })
-            .concat();
+            .collect::<Vec<_>>();
        a.sort_by(|a, b| match (a.1.target, b.1.target) {
            (Some(a), Some(b)) => a.len().cmp(&b.len()),
            (Some(_), None) => Ordering::Less,
@@ -95,6 +96,7 @@ mod assists {
    mod apply_demorgan;
    mod flip_comma;
    mod flip_binexpr;
+    mod flip_trait_bound;
    mod change_visibility;
    mod fill_match_arms;
    mod merge_match_arms;
@@ -104,7 +106,7 @@ mod assists {
    mod replace_if_let_with_match;
    mod split_import;
    mod remove_dbg;
-    pub(crate) mod auto_import;
+    pub(crate) mod add_import;
    mod add_missing_impl_members;
    mod move_guard;
    mod move_bounds;
@@ -121,11 +123,12 @@ mod assists {
            merge_match_arms::merge_match_arms,
            flip_comma::flip_comma,
            flip_binexpr::flip_binexpr,
+            flip_trait_bound::flip_trait_bound,
            introduce_variable::introduce_variable,
            replace_if_let_with_match::replace_if_let_with_match,
            split_import::split_import,
            remove_dbg::remove_dbg,
-            auto_import::auto_import,
+            add_import::add_import,
            add_missing_impl_members::add_missing_impl_members,
            add_missing_impl_members::add_missing_default_members,
            inline_local_variable::inline_local_varialbe,
@@ -155,51 +158,17 @@ mod helpers {
        before: &str,
        after: &str,
    ) {
-        check_assist_nth_action(assist, before, after, 0)
-    }
-    pub(crate) fn check_assist_range(
-        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
-        before: &str,
-        after: &str,
-    ) {
-        check_assist_range_nth_action(assist, before, after, 0)
-    }
-    pub(crate) fn check_assist_target(
-        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
-        before: &str,
-        target: &str,
-    ) {
-        check_assist_target_nth_action(assist, before, target, 0)
-    }
-    pub(crate) fn check_assist_range_target(
-        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
-        before: &str,
-        target: &str,
-    ) {
-        check_assist_range_target_nth_action(assist, before, target, 0)
-    }
-    pub(crate) fn check_assist_nth_action(
-        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
-        before: &str,
-        after: &str,
-        index: usize,
-    ) {
        let (before_cursor_pos, before) = extract_offset(before);
        let (db, _source_root, file_id) = MockDatabase::with_single_file(&before);
        let frange =
            FileRange { file_id, range: TextRange::offset_len(before_cursor_pos, 0.into()) };
        let assist =
            AssistCtx::with_ctx(&db, frange, true, assist).expect("code action is not applicable");
-        let labels_actions = match assist {
+        let action = match assist {
-            Assist::Unresolved(_) => unreachable!(),
+            Assist::Unresolved { .. } => unreachable!(),
-            Assist::Resolved(labels_actions) => labels_actions,
+            Assist::Resolved { action, .. } => action,
        };
-        let (_, action) = labels_actions.get(index).expect("expect assist action at index");
        let actual = action.edit.apply(&before);
        let actual_cursor_pos = match action.cursor_position {
            None => action
@@ -212,23 +181,21 @@ mod helpers {
        assert_eq_text!(after, &actual);
    }
-    pub(crate) fn check_assist_range_nth_action(
+    pub(crate) fn check_assist_range(
        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
        before: &str,
        after: &str,
-        index: usize,
    ) {
        let (range, before) = extract_range(before);
        let (db, _source_root, file_id) = MockDatabase::with_single_file(&before);
        let frange = FileRange { file_id, range };
        let assist =
            AssistCtx::with_ctx(&db, frange, true, assist).expect("code action is not applicable");
-        let labels_actions = match assist {
+        let action = match assist {
-            Assist::Unresolved(_) => unreachable!(),
+            Assist::Unresolved { .. } => unreachable!(),
-            Assist::Resolved(labels_actions) => labels_actions,
+            Assist::Resolved { action, .. } => action,
        };
-        let (_, action) = labels_actions.get(index).expect("expect assist action at index");
        let mut actual = action.edit.apply(&before);
        if let Some(pos) = action.cursor_position {
            actual = add_cursor(&actual, pos);
@@ -236,11 +203,10 @@ mod helpers {
        assert_eq_text!(after, &actual);
    }
-    pub(crate) fn check_assist_target_nth_action(
+    pub(crate) fn check_assist_target(
        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
        before: &str,
        target: &str,
-        index: usize,
    ) {
        let (before_cursor_pos, before) = extract_offset(before);
        let (db, _source_root, file_id) = MockDatabase::with_single_file(&before);
@@ -248,33 +214,30 @@ mod helpers {
            FileRange { file_id, range: TextRange::offset_len(before_cursor_pos, 0.into()) };
        let assist =
            AssistCtx::with_ctx(&db, frange, true, assist).expect("code action is not applicable");
-        let labels_actions = match assist {
+        let action = match assist {
-            Assist::Unresolved(_) => unreachable!(),
+            Assist::Unresolved { .. } => unreachable!(),
-            Assist::Resolved(labels_actions) => labels_actions,
+            Assist::Resolved { action, .. } => action,
        };
-        let (_, action) = labels_actions.get(index).expect("expect assist action at index");
        let range = action.target.expect("expected target on action");
        assert_eq_text!(&before[range.start().to_usize()..range.end().to_usize()], target);
    }
-    pub(crate) fn check_assist_range_target_nth_action(
+    pub(crate) fn check_assist_range_target(
        assist: fn(AssistCtx<MockDatabase>) -> Option<Assist>,
        before: &str,
        target: &str,
-        index: usize,
    ) {
        let (range, before) = extract_range(before);
        let (db, _source_root, file_id) = MockDatabase::with_single_file(&before);
        let frange = FileRange { file_id, range };
        let assist =
            AssistCtx::with_ctx(&db, frange, true, assist).expect("code action is not applicable");
-        let labels_actions = match assist {
+        let action = match assist {
-            Assist::Unresolved(_) => unreachable!(),
+            Assist::Unresolved { .. } => unreachable!(),
-            Assist::Resolved(labels_actions) => labels_actions,
+            Assist::Resolved { action, .. } => action,
        };
-        let (_, action) = labels_actions.get(index).expect("expect assist action at index");
        let range = action.target.expect("expected target on action");
        assert_eq_text!(&before[range.start().to_usize()..range.end().to_usize()], target);
    }
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index fc5d6d396..0d1ab4843 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -134,10 +134,7 @@ impl<T: SourceDatabaseExt> FileLoader for FileLoaderDelegate<&'_ T> {
    ) -> Option<FileId> {
        let path = {
            let mut path = self.0.file_relative_path(anchor);
-            // Workaround for relative path API: turn `lib.rs` into ``.
+            assert!(path.pop());
-            if !path.pop() {
-                path = RelativePathBuf::default();
-            }
            path.push(relative_path);
            path.normalize()
        };
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index 54c09788a..5df371bc0 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -19,12 +19,14 @@ ra_cfg = { path = "../ra_cfg" }
 ra_db = { path = "../ra_db" }
 mbe = { path = "../ra_mbe", package = "ra_mbe" }
 tt = { path = "../ra_tt", package = "ra_tt" }
+hir_expand = { path = "../ra_hir_expand", package = "ra_hir_expand" }
+hir_def = { path = "../ra_hir_def", package = "ra_hir_def" }
 test_utils = { path = "../test_utils" }
 ra_prof = { path = "../ra_prof" }
-chalk-solve = { git = "https://github.com/rust-lang/chalk.git" }
+chalk-solve = { git = "https://github.com/rust-lang/chalk.git", rev = "8314f2fcec8582a58c24b638f1a259d4145a0809" }
-chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git" }
+chalk-rust-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "8314f2fcec8582a58c24b638f1a259d4145a0809" }
-chalk-ir = { git = "https://github.com/rust-lang/chalk.git" }
+chalk-ir = { git = "https://github.com/rust-lang/chalk.git", rev = "8314f2fcec8582a58c24b638f1a259d4145a0809" }
 lalrpop-intern = "0.15.1"
 [dev-dependencies]
diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index 3e9cd3c63..4fa2062bd 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -3,13 +3,14 @@
 use std::sync::Arc;
+use hir_def::{type_ref::TypeRef, LocalEnumVariantId};
+use hir_expand::name::AsName;
 use ra_arena::{impl_arena_id, Arena, RawId};
 use ra_syntax::ast::{self, NameOwner, StructKind, TypeAscriptionOwner};
 use crate::{
    db::{AstDatabase, DefDatabase, HirDatabase},
-    type_ref::TypeRef,
+    Enum, EnumVariant, FieldSource, HasSource, Module, Name, Source, Struct, StructField,
-    AsName, Enum, EnumVariant, FieldSource, HasSource, Module, Name, Source, Struct, StructField,
 };
 impl Struct {
@@ -67,7 +68,7 @@ impl EnumVariant {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct EnumData {
    pub(crate) name: Option<Name>,
-    pub(crate) variants: Arena<EnumVariantId, EnumVariantData>,
+    pub(crate) variants: Arena<LocalEnumVariantId, EnumVariantData>,
 }
 impl EnumData {
@@ -84,10 +85,6 @@ impl EnumData {
    }
 }
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub(crate) struct EnumVariantId(RawId);
-impl_arena_id!(EnumVariantId);
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub(crate) struct EnumVariantData {
    pub(crate) name: Option<Name>,
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 8eb3c577d..b32aa145e 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -5,11 +5,17 @@ pub(crate) mod docs;
 use std::sync::Arc;
-use ra_db::{CrateId, Edition, FileId};
+use hir_def::{
+    builtin_type::BuiltinType,
+    type_ref::{Mutability, TypeRef},
+    CrateModuleId, LocalEnumVariantId, ModuleId,
+};
+use hir_expand::name::{self, AsName};
+use ra_db::{CrateId, Edition};
 use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
 use crate::{
-    adt::{EnumVariantId, StructFieldId, VariantDef},
+    adt::{StructFieldId, VariantDef},
    db::{AstDatabase, DefDatabase, HirDatabase},
    diagnostics::DiagnosticSink,
    expr::{validation::ExprValidator, Body, BodySourceMap},
@@ -19,20 +25,11 @@ use crate::{
        TypeAliasId,
    },
    impl_block::ImplBlock,
-    name::{
+    nameres::{ImportId, ModuleScope, Namespace},
-        BOOL, CHAR, F32, F64, I128, I16, I32, I64, I8, ISIZE, SELF_TYPE, STR, U128, U16, U32, U64,
-        U8, USIZE,
-    },
-    nameres::{CrateModuleId, ImportId, ModuleScope, Namespace},
    resolve::{Resolver, Scope, TypeNs},
    traits::TraitData,
-    ty::{
+    ty::{InferenceResult, TraitRef},
-        primitive::{FloatBitness, FloatTy, IntBitness, IntTy, Signedness},
+    Either, HasSource, Name, Ty,
-        InferenceResult, TraitRef,
-    },
-    type_ref::Mutability,
-    type_ref::TypeRef,
-    AsName, AstId, Either, HasSource, Name, Ty,
 };
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -67,8 +64,7 @@ impl Crate {
    pub fn root_module(self, db: &impl DefDatabase) -> Option<Module> {
        let module_id = db.crate_def_map(self).root();
-        let module = Module { krate: self, module_id };
+        Some(Module::new(self, module_id))
-        Some(module)
    }
    pub fn edition(self, db: &impl DefDatabase) -> Edition {
@@ -83,43 +79,7 @@ impl Crate {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Module {
-    pub(crate) krate: Crate,
+    pub(crate) id: ModuleId,
-    pub(crate) module_id: CrateModuleId,
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum BuiltinType {
-    Char,
-    Bool,
-    Str,
-    Int(IntTy),
-    Float(FloatTy),
-}
-impl BuiltinType {
-    #[rustfmt::skip]
-    pub(crate) const ALL: &'static [(Name, BuiltinType)] = &[
-        (CHAR, BuiltinType::Char),
-        (BOOL, BuiltinType::Bool),
-        (STR, BuiltinType::Str),
-        (ISIZE, BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::Xsize })),
-        (I8,    BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::X8 })),
-        (I16,   BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::X16 })),
-        (I32,   BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::X32 })),
-        (I64,   BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::X64 })),
-        (I128,  BuiltinType::Int(IntTy { signedness: Signedness::Signed, bitness: IntBitness::X128 })),
-        (USIZE, BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::Xsize })),
-        (U8,    BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X8 })),
-        (U16,   BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X16 })),
-        (U32,   BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X32 })),
-        (U64,   BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X64 })),
-        (U128,  BuiltinType::Int(IntTy { signedness: Signedness::Unsigned, bitness: IntBitness::X128 })),
-        (F32, BuiltinType::Float(FloatTy { bitness: FloatBitness::X32 })),
-        (F64, BuiltinType::Float(FloatTy { bitness: FloatBitness::X64 })),
-    ];
 }
 /// The defs which can be visible in the module.
@@ -148,39 +108,19 @@ impl_froms!(
    BuiltinType
 );
-pub enum ModuleSource {
+pub use hir_def::ModuleSource;
-    SourceFile(ast::SourceFile),
-    Module(ast::Module),
-}
-impl ModuleSource {
+impl Module {
-    pub(crate) fn new(
+    pub(crate) fn new(krate: Crate, crate_module_id: CrateModuleId) -> Module {
-        db: &(impl DefDatabase + AstDatabase),
+        Module { id: ModuleId { krate: krate.crate_id, module_id: crate_module_id } }
-        file_id: Option<FileId>,
-        decl_id: Option<AstId<ast::Module>>,
-    ) -> ModuleSource {
-        match (file_id, decl_id) {
-            (Some(file_id), _) => {
-                let source_file = db.parse(file_id).tree();
-                ModuleSource::SourceFile(source_file)
-            }
-            (None, Some(item_id)) => {
-                let module = item_id.to_node(db);
-                assert!(module.item_list().is_some(), "expected inline module");
-                ModuleSource::Module(module)
-            }
-            (None, None) => panic!(),
-        }
    }
-}
-impl Module {
    /// Name of this module.
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let parent = def_map[self.module_id].parent?;
+        let parent = def_map[self.id.module_id].parent?;
        def_map[parent].children.iter().find_map(|(name, module_id)| {
-            if *module_id == self.module_id {
+            if *module_id == self.id.module_id {
                Some(name.clone())
            } else {
                None
@@ -200,29 +140,29 @@ impl Module {
    }
    /// Returns the crate this module is part of.
-    pub fn krate(self, _db: &impl DefDatabase) -> Option<Crate> {
+    pub fn krate(self) -> Crate {
-        Some(self.krate)
+        Crate { crate_id: self.id.krate }
    }
    /// Topmost parent of this module. Every module has a `crate_root`, but some
    /// might be missing `krate`. This can happen if a module's file is not included
    /// in the module tree of any target in `Cargo.toml`.
    pub fn crate_root(self, db: &impl DefDatabase) -> Module {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
        self.with_module_id(def_map.root())
    }
    /// Finds a child module with the specified name.
    pub fn child(self, db: &impl HirDatabase, name: &Name) -> Option<Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let child_id = def_map[self.module_id].children.get(name)?;
+        let child_id = def_map[self.id.module_id].children.get(name)?;
        Some(self.with_module_id(*child_id))
    }
    /// Iterates over all child modules.
    pub fn children(self, db: &impl DefDatabase) -> impl Iterator<Item = Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let children = def_map[self.module_id]
+        let children = def_map[self.id.module_id]
            .children
            .iter()
            .map(|(_, module_id)| self.with_module_id(*module_id))
@@ -232,8 +172,8 @@ impl Module {
    /// Finds a parent module.
    pub fn parent(self, db: &impl DefDatabase) -> Option<Module> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let parent_id = def_map[self.module_id].parent?;
+        let parent_id = def_map[self.id.module_id].parent?;
        Some(self.with_module_id(parent_id))
    }
@@ -249,11 +189,11 @@ impl Module {
    /// Returns a `ModuleScope`: a set of items, visible in this module.
    pub fn scope(self, db: &impl HirDatabase) -> ModuleScope {
-        db.crate_def_map(self.krate)[self.module_id].scope.clone()
+        db.crate_def_map(self.krate())[self.id.module_id].scope.clone()
    }
    pub fn diagnostics(self, db: &impl HirDatabase, sink: &mut DiagnosticSink) {
-        db.crate_def_map(self.krate).add_diagnostics(db, self.module_id, sink);
+        db.crate_def_map(self.krate()).add_diagnostics(db, self.id.module_id, sink);
        for decl in self.declarations(db) {
            match decl {
                crate::ModuleDef::Function(f) => f.diagnostics(db, sink),
@@ -277,13 +217,13 @@ impl Module {
    }
    pub(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        Resolver::default().push_module_scope(def_map, self.module_id)
+        Resolver::default().push_module_scope(def_map, self.id.module_id)
    }
    pub fn declarations(self, db: &impl DefDatabase) -> Vec<ModuleDef> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        def_map[self.module_id]
+        def_map[self.id.module_id]
            .scope
            .entries()
            .filter_map(|(_name, res)| if res.import.is_none() { Some(res.def) } else { None })
@@ -303,7 +243,7 @@ impl Module {
    }
    fn with_module_id(self, module_id: CrateModuleId) -> Module {
-        Module { module_id, krate: self.krate }
+        Module::new(self.krate(), module_id)
    }
 }
@@ -340,11 +280,11 @@ pub struct Struct {
 impl Struct {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -402,7 +342,7 @@ impl Union {
    }
    pub fn module(self, db: &impl HirDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn ty(self, db: &impl HirDatabase) -> Ty {
@@ -428,11 +368,11 @@ pub struct Enum {
 impl Enum {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -470,7 +410,7 @@ impl Enum {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct EnumVariant {
    pub(crate) parent: Enum,
-    pub(crate) id: EnumVariantId,
+    pub(crate) id: LocalEnumVariantId,
 }
 impl EnumVariant {
@@ -523,12 +463,14 @@ impl Adt {
    }
    pub fn krate(self, db: &impl HirDatabase) -> Option<Crate> {
-        match self {
+        Some(
-            Adt::Struct(s) => s.module(db),
+            match self {
-            Adt::Union(s) => s.module(db),
+                Adt::Struct(s) => s.module(db),
-            Adt::Enum(e) => e.module(db),
+                Adt::Union(s) => s.module(db),
-        }
+                Adt::Enum(e) => e.module(db),
-        .krate(db)
+            }
+            .krate(),
+        )
    }
    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
@@ -643,7 +585,7 @@ impl FnData {
                let self_type = if let Some(type_ref) = self_param.ascribed_type() {
                    TypeRef::from_ast(type_ref)
                } else {
-                    let self_type = TypeRef::Path(SELF_TYPE.into());
+                    let self_type = TypeRef::Path(name::SELF_TYPE.into());
                    match self_param.kind() {
                        ast::SelfParamKind::Owned => self_type,
                        ast::SelfParamKind::Ref => {
@@ -692,11 +634,11 @@ impl FnData {
 impl Function {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn name(self, db: &impl HirDatabase) -> Name {
@@ -770,11 +712,11 @@ pub struct Const {
 impl Const {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
@@ -867,11 +809,11 @@ pub struct Static {
 impl Static {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
@@ -896,7 +838,7 @@ pub struct Trait {
 impl Trait {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
@@ -917,9 +859,7 @@ impl Trait {
            .where_predicates
            .iter()
            .filter_map(|pred| match &pred.type_ref {
-                TypeRef::Path(p) if p.as_ident() == Some(&crate::name::SELF_TYPE) => {
+                TypeRef::Path(p) if p.as_ident() == Some(&name::SELF_TYPE) => pred.bound.as_path(),
-                    pred.bound.as_path()
-                }
                _ => None,
            })
            .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path) {
@@ -998,11 +938,11 @@ pub struct TypeAlias {
 impl TypeAlias {
    pub fn module(self, db: &impl DefDatabase) -> Module {
-        self.id.module(db)
+        Module { id: self.id.module(db) }
    }
    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
-        self.module(db).krate(db)
+        Some(self.module(db).krate())
    }
    /// The containing impl block, if this is a method.
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index fdae26906..5c7f61eef 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -1,9 +1,6 @@
 //! FIXME: write short doc here
-use ra_syntax::{
+use ra_syntax::ast::{self, AstNode};
-    ast::{self, AstNode},
-    SyntaxNode,
-};
 use crate::{
    db::{AstDatabase, DefDatabase, HirDatabase},
@@ -12,34 +9,21 @@ use crate::{
    ModuleSource, Static, Struct, StructField, Trait, TypeAlias, Union,
 };
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub use hir_def::Source;
-pub struct Source<T> {
-    pub file_id: HirFileId,
-    pub ast: T,
-}
 pub trait HasSource {
    type Ast;
    fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<Self::Ast>;
 }
-impl<T> Source<T> {
-    pub(crate) fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
-        Source { file_id: self.file_id, ast: f(self.ast) }
-    }
-    pub(crate) fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
-        db.parse_or_expand(self.file_id).expect("source created from invalid file")
-    }
-}
 /// NB: Module is !HasSource, because it has two source nodes at the same time:
 /// definition and declaration.
 impl Module {
    /// Returns a node which defines this module. That is, a file or a `mod foo {}` with items.
    pub fn definition_source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<ModuleSource> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let decl_id = def_map[self.module_id].declaration;
+        let decl_id = def_map[self.id.module_id].declaration;
-        let file_id = def_map[self.module_id].definition;
+        let file_id = def_map[self.id.module_id].definition;
        let ast = ModuleSource::new(db, file_id, decl_id);
        let file_id = file_id.map(HirFileId::from).unwrap_or_else(|| decl_id.unwrap().file_id());
        Source { file_id, ast }
@@ -51,8 +35,8 @@ impl Module {
        self,
        db: &(impl DefDatabase + AstDatabase),
    ) -> Option<Source<ast::Module>> {
-        let def_map = db.crate_def_map(self.krate);
+        let def_map = db.crate_def_map(self.krate());
-        let decl = def_map[self.module_id].declaration?;
+        let decl = def_map[self.id.module_id].declaration?;
        let ast = decl.to_node(db);
        Some(Source { file_id: decl.file_id(), ast })
    }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 489a3b19c..ebfd970eb 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -2,8 +2,8 @@
 use std::sync::Arc;
-use ra_db::{salsa, SourceDatabase};
+use ra_db::salsa;
-use ra_syntax::{ast, Parse, SmolStr, SyntaxNode};
+use ra_syntax::SmolStr;
 use crate::{
    adt::{EnumData, StructData},
@@ -12,81 +12,30 @@ use crate::{
    ids,
    impl_block::{ImplBlock, ImplSourceMap, ModuleImplBlocks},
    lang_item::{LangItemTarget, LangItems},
-    nameres::{CrateDefMap, ImportSourceMap, Namespace, RawItems},
+    nameres::{CrateDefMap, Namespace},
    traits::TraitData,
    ty::{
        method_resolution::CrateImplBlocks, traits::Impl, CallableDef, FnSig, GenericPredicate,
        InferenceResult, Substs, Ty, TypableDef, TypeCtor,
    },
    type_alias::TypeAliasData,
-    AstIdMap, Const, ConstData, Crate, DefWithBody, Enum, ErasedFileAstId, ExprScopes, FnData,
+    Const, ConstData, Crate, DefWithBody, Enum, ExprScopes, FnData, Function, Module, Static,
-    Function, HirFileId, MacroCallLoc, MacroDefId, Module, Static, Struct, StructField, Trait,
+    Struct, StructField, Trait, TypeAlias,
-    TypeAlias,
 };
-/// We store all interned things in the single QueryGroup.
+pub use hir_def::db::{
-///
+    DefDatabase2, DefDatabase2Storage, InternDatabase, InternDatabaseStorage, RawItemsQuery,
-/// This is done mainly to allow both "volatile" `AstDatabase` and "stable"
+    RawItemsWithSourceMapQuery,
-/// `DefDatabase` to access macros, without adding hard dependencies between the
+};
-/// two.
+pub use hir_expand::db::{
-#[salsa::query_group(InternDatabaseStorage)]
+    AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
-pub trait InternDatabase: SourceDatabase {
+    ParseMacroQuery,
-    #[salsa::interned]
+};
-    fn intern_macro(&self, macro_call: MacroCallLoc) -> ids::MacroCallId;
-    #[salsa::interned]
-    fn intern_function(&self, loc: ids::ItemLoc<ast::FnDef>) -> ids::FunctionId;
-    #[salsa::interned]
-    fn intern_struct(&self, loc: ids::ItemLoc<ast::StructDef>) -> ids::StructId;
-    #[salsa::interned]
-    fn intern_enum(&self, loc: ids::ItemLoc<ast::EnumDef>) -> ids::EnumId;
-    #[salsa::interned]
-    fn intern_const(&self, loc: ids::ItemLoc<ast::ConstDef>) -> ids::ConstId;
-    #[salsa::interned]
-    fn intern_static(&self, loc: ids::ItemLoc<ast::StaticDef>) -> ids::StaticId;
-    #[salsa::interned]
-    fn intern_trait(&self, loc: ids::ItemLoc<ast::TraitDef>) -> ids::TraitId;
-    #[salsa::interned]
-    fn intern_type_alias(&self, loc: ids::ItemLoc<ast::TypeAliasDef>) -> ids::TypeAliasId;
-    // Interned IDs for Chalk integration
-    #[salsa::interned]
-    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
-    #[salsa::interned]
-    fn intern_impl(&self, impl_: Impl) -> ids::GlobalImplId;
-}
-/// This database has access to source code, so queries here are not really
-/// incremental.
-#[salsa::query_group(AstDatabaseStorage)]
-pub trait AstDatabase: InternDatabase {
-    #[salsa::invoke(crate::source_id::AstIdMap::ast_id_map_query)]
-    fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;
-    #[salsa::transparent]
-    #[salsa::invoke(crate::source_id::AstIdMap::file_item_query)]
-    fn ast_id_to_node(&self, file_id: HirFileId, ast_id: ErasedFileAstId) -> SyntaxNode;
-    #[salsa::transparent]
-    #[salsa::invoke(crate::ids::HirFileId::parse_or_expand_query)]
-    fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode>;
-    #[salsa::invoke(crate::ids::HirFileId::parse_macro_query)]
-    fn parse_macro(&self, macro_file: ids::MacroFile) -> Option<Parse<SyntaxNode>>;
-    #[salsa::invoke(crate::ids::macro_def_query)]
-    fn macro_def(&self, macro_id: MacroDefId) -> Option<Arc<mbe::MacroRules>>;
-    #[salsa::invoke(crate::ids::macro_arg_query)]
-    fn macro_arg(&self, macro_call: ids::MacroCallId) -> Option<Arc<tt::Subtree>>;
-    #[salsa::invoke(crate::ids::macro_expand_query)]
-    fn macro_expand(&self, macro_call: ids::MacroCallId) -> Result<Arc<tt::Subtree>, String>;
-}
 // This database uses `AstDatabase` internally,
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
-pub trait DefDatabase: InternDatabase + HirDebugDatabase {
+pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
    #[salsa::invoke(crate::adt::StructData::struct_data_query)]
    fn struct_data(&self, s: Struct) -> Arc<StructData>;
@@ -99,15 +48,6 @@ pub trait DefDatabase: InternDatabase + HirDebugDatabase {
    #[salsa::invoke(crate::traits::TraitItemsIndex::trait_items_index)]
    fn trait_items_index(&self, module: Module) -> crate::traits::TraitItemsIndex;
-    #[salsa::invoke(RawItems::raw_items_with_source_map_query)]
-    fn raw_items_with_source_map(
-        &self,
-        file_id: HirFileId,
-    ) -> (Arc<RawItems>, Arc<ImportSourceMap>);
-    #[salsa::invoke(RawItems::raw_items_query)]
-    fn raw_items(&self, file_id: HirFileId) -> Arc<RawItems>;
    #[salsa::invoke(CrateDefMap::crate_def_map_query)]
    fn crate_def_map(&self, krate: Crate) -> Arc<CrateDefMap>;
@@ -202,6 +142,12 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
    #[salsa::invoke(crate::ty::traits::trait_solver_query)]
    fn trait_solver(&self, krate: Crate) -> crate::ty::traits::TraitSolver;
+    // Interned IDs for Chalk integration
+    #[salsa::interned]
+    fn intern_type_ctor(&self, type_ctor: TypeCtor) -> ids::TypeCtorId;
+    #[salsa::interned]
+    fn intern_impl(&self, impl_: Impl) -> ids::GlobalImplId;
    #[salsa::invoke(crate::ty::traits::chalk::associated_ty_data_query)]
    fn associated_ty_data(&self, id: chalk_ir::TypeId) -> Arc<chalk_rust_ir::AssociatedTyDatum>;
diff --git a/crates/ra_hir/src/debug.rs b/crates/ra_hir/src/debug.rs
index 48b69000b..4f3e922c3 100644
--- a/crates/ra_hir/src/debug.rs
+++ b/crates/ra_hir/src/debug.rs
@@ -36,12 +36,6 @@ impl Module {
    }
 }
-impl HirFileId {
-    pub fn debug(self, db: &impl HirDebugDatabase) -> impl fmt::Debug + '_ {
-        debug_fn(move |fmt| db.debug_hir_file_id(self, fmt))
-    }
-}
 pub trait HirDebugHelper: HirDatabase {
    fn crate_name(&self, _krate: CrateId) -> Option<String> {
        None
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index d238741ba..6e23197a4 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -6,15 +6,17 @@ pub(crate) mod validation;
 use std::{ops::Index, sync::Arc};
+use hir_def::{
+    path::GenericArgs,
+    type_ref::{Mutability, TypeRef},
+};
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
 use ra_syntax::{ast, AstPtr};
 use rustc_hash::FxHashMap;
 use crate::{
    db::HirDatabase,
-    path::GenericArgs,
    ty::primitive::{UncertainFloatTy, UncertainIntTy},
-    type_ref::{Mutability, TypeRef},
    DefWithBody, Either, HasSource, Name, Path, Resolver, Source,
 };
diff --git a/crates/ra_hir/src/expr/lower.rs b/crates/ra_hir/src/expr/lower.rs
index 50ea429ea..6463dd65e 100644
--- a/crates/ra_hir/src/expr/lower.rs
+++ b/crates/ra_hir/src/expr/lower.rs
@@ -1,5 +1,10 @@
 //! FIXME: write short doc here
+use hir_def::{path::GenericArgs, type_ref::TypeRef};
+use hir_expand::{
+    hygiene::Hygiene,
+    name::{self, AsName, Name},
+};
 use ra_arena::Arena;
 use ra_syntax::{
    ast::{
@@ -12,11 +17,8 @@ use test_utils::tested_by;
 use crate::{
    db::HirDatabase,
-    name::{AsName, Name, SELF_PARAM},
-    path::GenericArgs,
    ty::primitive::{FloatTy, IntTy, UncertainFloatTy, UncertainIntTy},
-    type_ref::TypeRef,
+    AstId, DefWithBody, Either, HirFileId, MacroCallLoc, MacroFileKind, Mutability, Path, Resolver,
-    DefWithBody, Either, HirFileId, MacroCallLoc, MacroFileKind, Mutability, Path, Resolver,
    Source,
 };
@@ -78,7 +80,7 @@ where
                let ptr = AstPtr::new(&self_param);
                let param_pat = self.alloc_pat(
                    Pat::Bind {
-                        name: SELF_PARAM,
+                        name: name::SELF_PARAM,
                        mode: BindingAnnotation::Unannotated,
                        subpat: None,
                    },
@@ -458,15 +460,14 @@ where
            ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
            ast::Expr::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
            ast::Expr::MacroCall(e) => {
-                let ast_id = self
+                let ast_id = AstId::new(
-                    .db
+                    self.current_file_id,
-                    .ast_id_map(self.current_file_id)
+                    self.db.ast_id_map(self.current_file_id).ast_id(&e),
-                    .ast_id(&e)
+                );
-                    .with_file_id(self.current_file_id);
                if let Some(path) = e.path().and_then(|path| self.parse_path(path)) {
                    if let Some(def) = self.resolver.resolve_path_as_macro(self.db, &path) {
-                        let call_id = MacroCallLoc { def: def.id, ast_id }.id(self.db);
+                        let call_id = self.db.intern_macro(MacroCallLoc { def: def.id, ast_id });
                        let file_id = call_id.as_file(MacroFileKind::Expr);
                        if let Some(node) = self.db.parse_or_expand(file_id) {
                            if let Some(expr) = ast::Expr::cast(node) {
@@ -596,7 +597,8 @@ where
    }
    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
-        Path::from_src(Source { ast: path, file_id: self.current_file_id }, self.db)
+        let hygiene = Hygiene::new(self.db, self.current_file_id);
+        Path::from_src(path, &hygiene)
    }
 }
diff --git a/crates/ra_hir/src/expr/validation.rs b/crates/ra_hir/src/expr/validation.rs
index 1aa853c3e..c685edda1 100644
--- a/crates/ra_hir/src/expr/validation.rs
+++ b/crates/ra_hir/src/expr/validation.rs
@@ -2,6 +2,7 @@
 use std::sync::Arc;
+use hir_def::path::known;
 use ra_syntax::ast;
 use rustc_hash::FxHashSet;
@@ -9,7 +10,6 @@ use crate::{
    db::HirDatabase,
    diagnostics::{DiagnosticSink, MissingFields, MissingOkInTailExpr},
    expr::AstPtr,
-    path::known,
    ty::{ApplicationTy, InferenceResult, Ty, TypeCtor},
    Adt, Function, Name, Path,
 };
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index f80d8eb5f..a9de01455 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -1,17 +1,12 @@
 //! FIXME: write short doc here
-use ra_db::{FileId, FilePosition};
+use hir_expand::name::AsName;
-use ra_syntax::{
+use ra_syntax::ast::{self, AstNode, NameOwner};
-    algo::find_node_at_offset,
-    ast::{self, AstNode, NameOwner},
-    SyntaxNode,
-};
 use crate::{
    db::{AstDatabase, DefDatabase, HirDatabase},
    ids::{AstItemDef, LocationCtx},
-    name::AsName,
+    AstId, Const, Crate, Enum, EnumVariant, FieldSource, Function, HasSource, ImplBlock, Module,
-    Const, Crate, Enum, EnumVariant, FieldSource, Function, HasSource, ImplBlock, Module,
    ModuleSource, Source, Static, Struct, StructField, Trait, TypeAlias, Union, VariantDef,
 };
@@ -129,41 +124,6 @@ impl FromSource for StructField {
    }
 }
-// FIXME: simplify it
-impl ModuleSource {
-    pub fn from_position(
-        db: &(impl DefDatabase + AstDatabase),
-        position: FilePosition,
-    ) -> ModuleSource {
-        let parse = db.parse(position.file_id);
-        match &find_node_at_offset::<ast::Module>(parse.tree().syntax(), position.offset) {
-            Some(m) if !m.has_semi() => ModuleSource::Module(m.clone()),
-            _ => {
-                let source_file = parse.tree();
-                ModuleSource::SourceFile(source_file)
-            }
-        }
-    }
-    pub fn from_child_node(
-        db: &(impl DefDatabase + AstDatabase),
-        file_id: FileId,
-        child: &SyntaxNode,
-    ) -> ModuleSource {
-        if let Some(m) = child.ancestors().filter_map(ast::Module::cast).find(|it| !it.has_semi()) {
-            ModuleSource::Module(m)
-        } else {
-            let source_file = db.parse(file_id).tree();
-            ModuleSource::SourceFile(source_file)
-        }
-    }
-    pub fn from_file_id(db: &(impl DefDatabase + AstDatabase), file_id: FileId) -> ModuleSource {
-        let source_file = db.parse(file_id).tree();
-        ModuleSource::SourceFile(source_file)
-    }
-}
 impl Module {
    pub fn from_declaration(db: &impl HirDatabase, src: Source<ast::Module>) -> Option<Self> {
        let src_parent = Source {
@@ -183,7 +143,7 @@ impl Module {
            ModuleSource::Module(ref module) => {
                assert!(!module.has_semi());
                let ast_id_map = db.ast_id_map(src.file_id);
-                let item_id = ast_id_map.ast_id(module).with_file_id(src.file_id);
+                let item_id = AstId::new(src.file_id, ast_id_map.ast_id(module));
                Some(item_id)
            }
            ModuleSource::SourceFile(_) => None,
@@ -195,7 +155,7 @@ impl Module {
            .find_map(|krate| {
                let def_map = db.crate_def_map(krate);
                let module_id = def_map.find_module_by_source(src.file_id, decl_id)?;
-                Some(Module { krate, module_id })
+                Some(Module::new(krate, module_id))
            })
    }
 }
@@ -208,6 +168,6 @@ where
    let module_src =
        crate::ModuleSource::from_child_node(db, src.file_id.original_file(db), &src.ast.syntax());
    let module = Module::from_definition(db, Source { file_id: src.file_id, ast: module_src })?;
-    let ctx = LocationCtx::new(db, module, src.file_id);
+    let ctx = LocationCtx::new(db, module.id, src.file_id);
    Some(DEF::from_ast(ctx, &src.ast))
 }
diff --git a/crates/ra_hir/src/generics.rs b/crates/ra_hir/src/generics.rs
index 4ce7551c3..52e1fbf29 100644
--- a/crates/ra_hir/src/generics.rs
+++ b/crates/ra_hir/src/generics.rs
@@ -5,15 +5,17 @@
 use std::sync::Arc;
+use hir_def::{
+    path::Path,
+    type_ref::{TypeBound, TypeRef},
+};
+use hir_expand::name::{self, AsName};
 use ra_syntax::ast::{self, DefaultTypeParamOwner, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 use crate::{
    db::{AstDatabase, DefDatabase, HirDatabase},
-    name::SELF_TYPE,
+    Adt, Const, Container, Enum, EnumVariant, Function, HasSource, ImplBlock, Name, Struct, Trait,
-    path::Path,
+    TypeAlias, Union,
-    type_ref::{TypeBound, TypeRef},
-    Adt, AsName, Const, Container, Enum, EnumVariant, Function, HasSource, ImplBlock, Name, Struct,
-    Trait, TypeAlias, Union,
 };
 /// Data about a generic parameter (to a function, struct, impl, ...).
@@ -94,11 +96,15 @@ impl GenericParams {
            GenericDef::Adt(Adt::Enum(it)) => generics.fill(&it.source(db).ast, start),
            GenericDef::Trait(it) => {
                // traits get the Self type as an implicit first type parameter
-                generics.params.push(GenericParam { idx: start, name: SELF_TYPE, default: None });
+                generics.params.push(GenericParam {
+                    idx: start,
+                    name: name::SELF_TYPE,
+                    default: None,
+                });
                generics.fill(&it.source(db).ast, start + 1);
                // 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(SELF_TYPE.into());
+                let self_param = TypeRef::Path(name::SELF_TYPE.into());
                generics.fill_bounds(&it.source(db).ast, self_param);
            }
            GenericDef::TypeAlias(it) => generics.fill(&it.source(db).ast, start),
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 499dcafea..fe083c0c6 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,168 +1,17 @@
-//! FIXME: write short doc here
+//! hir makes heavy use of ids: integer (u32) handlers to various things. You
+//! can think of id as a pointer (but without a lifetime) or a file descriptor
-use std::{
+//! (but for hir objects).
-    hash::{Hash, Hasher},
+//!
-    sync::Arc,
+//! This module defines a bunch of ids we are using. The most important ones are
-};
+//! probably `HirFileId` and `DefId`.
-use mbe::MacroRules;
+use ra_db::salsa;
-use ra_db::{salsa, FileId};
-use ra_prof::profile;
+pub use hir_def::{
-use ra_syntax::{ast, AstNode, Parse, SyntaxNode};
+    AstItemDef, ConstId, EnumId, FunctionId, ItemLoc, LocationCtx, StaticId, StructId, TraitId,
+    TypeAliasId,
-use crate::{
-    db::{AstDatabase, DefDatabase, InternDatabase},
-    AstId, Crate, FileAstId, Module, Source,
 };
+pub use hir_expand::{HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFile, MacroFileKind};
-/// hir makes heavy use of ids: integer (u32) handlers to various things. You
-/// can think of id as a pointer (but without a lifetime) or a file descriptor
-/// (but for hir objects).
-///
-/// This module defines a bunch of ids we are using. The most important ones are
-/// probably `HirFileId` and `DefId`.
-/// Input to the analyzer is a set of files, where each file is identified by
-/// `FileId` and contains source code. However, another source of source code in
-/// Rust are macros: each macro can be thought of as producing a "temporary
-/// file". To assign an id to such a file, we use the id of the macro call that
-/// produced the file. So, a `HirFileId` is either a `FileId` (source code
-/// written by user), or a `MacroCallId` (source code produced by macro).
-///
-/// What is a `MacroCallId`? Simplifying, it's a `HirFileId` of a file
-/// containing the call plus the offset of the macro call in the file. Note that
-/// this is a recursive definition! However, the size_of of `HirFileId` is
-/// finite (because everything bottoms out at the real `FileId`) and small
-/// (`MacroCallId` uses the location interner).
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct HirFileId(HirFileIdRepr);
-impl HirFileId {
-    /// For macro-expansion files, returns the file original source file the
-    /// expansion originated from.
-    pub fn original_file(self, db: &impl InternDatabase) -> FileId {
-        match self.0 {
-            HirFileIdRepr::File(file_id) => file_id,
-            HirFileIdRepr::Macro(macro_file) => {
-                let loc = macro_file.macro_call_id.loc(db);
-                loc.ast_id.file_id().original_file(db)
-            }
-        }
-    }
-    /// Get the crate which the macro lives in, if it is a macro file.
-    pub(crate) fn macro_crate(self, db: &impl AstDatabase) -> Option<Crate> {
-        match self.0 {
-            HirFileIdRepr::File(_) => None,
-            HirFileIdRepr::Macro(macro_file) => {
-                let loc = macro_file.macro_call_id.loc(db);
-                Some(loc.def.krate)
-            }
-        }
-    }
-    pub(crate) fn parse_or_expand_query(
-        db: &impl AstDatabase,
-        file_id: HirFileId,
-    ) -> Option<SyntaxNode> {
-        match file_id.0 {
-            HirFileIdRepr::File(file_id) => Some(db.parse(file_id).tree().syntax().clone()),
-            HirFileIdRepr::Macro(macro_file) => {
-                db.parse_macro(macro_file).map(|it| it.syntax_node())
-            }
-        }
-    }
-    pub(crate) fn parse_macro_query(
-        db: &impl AstDatabase,
-        macro_file: MacroFile,
-    ) -> Option<Parse<SyntaxNode>> {
-        let _p = profile("parse_macro_query");
-        let macro_call_id = macro_file.macro_call_id;
-        let tt = db
-            .macro_expand(macro_call_id)
-            .map_err(|err| {
-                // Note:
-                // The final goal we would like to make all parse_macro success,
-                // such that the following log will not call anyway.
-                log::warn!("fail on macro_parse: (reason: {})", err,);
-            })
-            .ok()?;
-        match macro_file.macro_file_kind {
-            MacroFileKind::Items => mbe::token_tree_to_items(&tt).ok().map(Parse::to_syntax),
-            MacroFileKind::Expr => mbe::token_tree_to_expr(&tt).ok().map(Parse::to_syntax),
-        }
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-enum HirFileIdRepr {
-    File(FileId),
-    Macro(MacroFile),
-}
-#[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(crate) enum MacroFileKind {
-    Items,
-    Expr,
-}
-impl From<FileId> for HirFileId {
-    fn from(file_id: FileId) -> HirFileId {
-        HirFileId(HirFileIdRepr::File(file_id))
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct MacroDefId {
-    pub(crate) ast_id: AstId<ast::MacroCall>,
-    pub(crate) krate: Crate,
-}
-pub(crate) fn macro_def_query(db: &impl AstDatabase, id: MacroDefId) -> Option<Arc<MacroRules>> {
-    let macro_call = id.ast_id.to_node(db);
-    let arg = macro_call.token_tree()?;
-    let (tt, _) = mbe::ast_to_token_tree(&arg).or_else(|| {
-        log::warn!("fail on macro_def to token tree: {:#?}", arg);
-        None
-    })?;
-    let rules = MacroRules::parse(&tt).ok().or_else(|| {
-        log::warn!("fail on macro_def parse: {:#?}", tt);
-        None
-    })?;
-    Some(Arc::new(rules))
-}
-pub(crate) fn macro_arg_query(db: &impl AstDatabase, id: MacroCallId) -> Option<Arc<tt::Subtree>> {
-    let loc = id.loc(db);
-    let macro_call = loc.ast_id.to_node(db);
-    let arg = macro_call.token_tree()?;
-    let (tt, _) = mbe::ast_to_token_tree(&arg)?;
-    Some(Arc::new(tt))
-}
-pub(crate) fn macro_expand_query(
-    db: &impl AstDatabase,
-    id: MacroCallId,
-) -> Result<Arc<tt::Subtree>, String> {
-    let loc = id.loc(db);
-    let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;
-    let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
-    let tt = macro_rules.expand(&macro_arg).map_err(|err| format!("{:?}", err))?;
-    // Set a hard limit for the expanded tt
-    let count = tt.count();
-    if count > 65536 {
-        return Err(format!("Total tokens count exceed limit : count = {}", count));
-    }
-    Ok(Arc::new(tt))
-}
 macro_rules! impl_intern_key {
    ($name:ident) => {
@@ -177,192 +26,6 @@ macro_rules! impl_intern_key {
    };
 }
-/// `MacroCallId` identifies a particular macro invocation, like
-/// `println!("Hello, {}", world)`.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct MacroCallId(salsa::InternId);
-impl_intern_key!(MacroCallId);
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct MacroCallLoc {
-    pub(crate) def: MacroDefId,
-    pub(crate) ast_id: AstId<ast::MacroCall>,
-}
-impl MacroCallId {
-    pub(crate) fn loc(self, db: &impl InternDatabase) -> MacroCallLoc {
-        db.lookup_intern_macro(self)
-    }
-    pub(crate) fn as_file(self, kind: MacroFileKind) -> HirFileId {
-        let macro_file = MacroFile { macro_call_id: self, macro_file_kind: kind };
-        HirFileId(HirFileIdRepr::Macro(macro_file))
-    }
-}
-impl MacroCallLoc {
-    pub(crate) fn id(self, db: &impl InternDatabase) -> MacroCallId {
-        db.intern_macro(self)
-    }
-}
-#[derive(Debug)]
-pub struct ItemLoc<N: AstNode> {
-    pub(crate) module: Module,
-    ast_id: AstId<N>,
-}
-impl<N: AstNode> PartialEq for ItemLoc<N> {
-    fn eq(&self, other: &Self) -> bool {
-        self.module == other.module && self.ast_id == other.ast_id
-    }
-}
-impl<N: AstNode> Eq for ItemLoc<N> {}
-impl<N: AstNode> Hash for ItemLoc<N> {
-    fn hash<H: Hasher>(&self, hasher: &mut H) {
-        self.module.hash(hasher);
-        self.ast_id.hash(hasher);
-    }
-}
-impl<N: AstNode> Clone for ItemLoc<N> {
-    fn clone(&self) -> ItemLoc<N> {
-        ItemLoc { module: self.module, ast_id: self.ast_id }
-    }
-}
-#[derive(Clone, Copy)]
-pub(crate) struct LocationCtx<DB> {
-    db: DB,
-    module: Module,
-    file_id: HirFileId,
-}
-impl<'a, DB: DefDatabase> LocationCtx<&'a DB> {
-    pub(crate) fn new(db: &'a DB, module: Module, file_id: HirFileId) -> LocationCtx<&'a DB> {
-        LocationCtx { db, module, file_id }
-    }
-}
-impl<'a, DB: DefDatabase + AstDatabase> LocationCtx<&'a DB> {
-    pub(crate) fn to_def<N, DEF>(self, ast: &N) -> DEF
-    where
-        N: AstNode,
-        DEF: AstItemDef<N>,
-    {
-        DEF::from_ast(self, ast)
-    }
-}
-pub(crate) trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<N>) -> Self;
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<N>;
-    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + DefDatabase)>, ast: &N) -> Self {
-        let items = ctx.db.ast_id_map(ctx.file_id);
-        let item_id = items.ast_id(ast);
-        Self::from_ast_id(ctx, item_id)
-    }
-    fn from_ast_id(ctx: LocationCtx<&impl DefDatabase>, ast_id: FileAstId<N>) -> Self {
-        let loc = ItemLoc { module: ctx.module, ast_id: ast_id.with_file_id(ctx.file_id) };
-        Self::intern(ctx.db, loc)
-    }
-    fn source(self, db: &(impl AstDatabase + DefDatabase)) -> Source<N> {
-        let loc = self.lookup_intern(db);
-        let ast = loc.ast_id.to_node(db);
-        Source { file_id: loc.ast_id.file_id(), ast }
-    }
-    fn module(self, db: &impl DefDatabase) -> Module {
-        let loc = self.lookup_intern(db);
-        loc.module
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct FunctionId(salsa::InternId);
-impl_intern_key!(FunctionId);
-impl AstItemDef<ast::FnDef> for FunctionId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
-        db.intern_function(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::FnDef> {
-        db.lookup_intern_function(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StructId(salsa::InternId);
-impl_intern_key!(StructId);
-impl AstItemDef<ast::StructDef> for StructId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
-        db.intern_struct(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::StructDef> {
-        db.lookup_intern_struct(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct EnumId(salsa::InternId);
-impl_intern_key!(EnumId);
-impl AstItemDef<ast::EnumDef> for EnumId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
-        db.intern_enum(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::EnumDef> {
-        db.lookup_intern_enum(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct ConstId(salsa::InternId);
-impl_intern_key!(ConstId);
-impl AstItemDef<ast::ConstDef> for ConstId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
-        db.intern_const(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::ConstDef> {
-        db.lookup_intern_const(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StaticId(salsa::InternId);
-impl_intern_key!(StaticId);
-impl AstItemDef<ast::StaticDef> for StaticId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
-        db.intern_static(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::StaticDef> {
-        db.lookup_intern_static(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TraitId(salsa::InternId);
-impl_intern_key!(TraitId);
-impl AstItemDef<ast::TraitDef> for TraitId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
-        db.intern_trait(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::TraitDef> {
-        db.lookup_intern_trait(self)
-    }
-}
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TypeAliasId(salsa::InternId);
-impl_intern_key!(TypeAliasId);
-impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
-    fn intern(db: &impl DefDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
-        db.intern_type_alias(loc)
-    }
-    fn lookup_intern(self, db: &impl DefDatabase) -> ItemLoc<ast::TypeAliasDef> {
-        db.lookup_intern_type_alias(self)
-    }
-}
 /// This exists just for Chalk, because Chalk just has a single `StructId` where
 /// we have different kinds of ADTs, primitive types and special type
 /// constructors like tuples and function pointers.
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 33ef87563..b1a014074 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -3,6 +3,8 @@
 use rustc_hash::FxHashMap;
 use std::sync::Arc;
+use hir_def::{attr::Attr, type_ref::TypeRef};
+use hir_expand::hygiene::Hygiene;
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
 use ra_cfg::CfgOptions;
 use ra_syntax::{
@@ -11,7 +13,6 @@ use ra_syntax::{
 };
 use crate::{
-    attr::Attr,
    code_model::{Module, ModuleSource},
    db::{AstDatabase, DefDatabase, HirDatabase},
    generics::HasGenericParams,
@@ -19,8 +20,7 @@ use crate::{
    ids::MacroCallLoc,
    resolve::Resolver,
    ty::Ty,
-    type_ref::TypeRef,
+    AssocItem, AstId, Const, Function, HasSource, HirFileId, MacroFileKind, Path, Source, TraitRef,
-    AssocItem, Const, Function, HasSource, HirFileId, MacroFileKind, Path, Source, TraitRef,
    TypeAlias,
 };
@@ -129,7 +129,7 @@ impl ImplData {
    ) -> Self {
        let target_trait = node.target_trait().map(TypeRef::from_ast);
        let target_type = TypeRef::from_ast_opt(node.target_type());
-        let ctx = LocationCtx::new(db, module, file_id);
+        let ctx = LocationCtx::new(db, module.id, file_id);
        let negative = node.is_negative();
        let items = if let Some(item_list) = node.item_list() {
            item_list
@@ -182,7 +182,7 @@ impl ModuleImplBlocks {
    ) -> (Arc<ModuleImplBlocks>, Arc<ImplSourceMap>) {
        let mut source_map = ImplSourceMap::default();
        let crate_graph = db.crate_graph();
-        let cfg_options = crate_graph.cfg_options(module.krate.crate_id());
+        let cfg_options = crate_graph.cfg_options(module.id.krate);
        let result = ModuleImplBlocks::collect(db, cfg_options, module, &mut source_map);
        (Arc::new(result), Arc::new(source_map))
@@ -228,10 +228,11 @@ impl ModuleImplBlocks {
        owner: &dyn ast::ModuleItemOwner,
        file_id: HirFileId,
    ) {
+        let hygiene = Hygiene::new(db, file_id);
        for item in owner.items_with_macros() {
            match item {
                ast::ItemOrMacro::Item(ast::ModuleItem::ImplBlock(impl_block_ast)) => {
-                    let attrs = Attr::from_attrs_owner(file_id, &impl_block_ast, db);
+                    let attrs = Attr::from_attrs_owner(&impl_block_ast, &hygiene);
                    if attrs.map_or(false, |attrs| {
                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
                    }) {
@@ -248,7 +249,7 @@ impl ModuleImplBlocks {
                }
                ast::ItemOrMacro::Item(_) => (),
                ast::ItemOrMacro::Macro(macro_call) => {
-                    let attrs = Attr::from_attrs_owner(file_id, &macro_call, db);
+                    let attrs = Attr::from_attrs_owner(&macro_call, &hygiene);
                    if attrs.map_or(false, |attrs| {
                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
                    }) {
@@ -256,14 +257,13 @@ impl ModuleImplBlocks {
                    }
                    //FIXME: we should really cut down on the boilerplate required to process a macro
-                    let ast_id = db.ast_id_map(file_id).ast_id(&macro_call).with_file_id(file_id);
+                    let ast_id = AstId::new(file_id, db.ast_id_map(file_id).ast_id(&macro_call));
-                    if let Some(path) = macro_call
+                    if let Some(path) =
-                        .path()
+                        macro_call.path().and_then(|path| Path::from_src(path, &hygiene))
-                        .and_then(|path| Path::from_src(Source { ast: path, file_id }, db))
                    {
                        if let Some(def) = self.module.resolver(db).resolve_path_as_macro(db, &path)
                        {
-                            let call_id = MacroCallLoc { def: def.id, ast_id }.id(db);
+                            let call_id = db.intern_macro(MacroCallLoc { def: def.id, ast_id });
                            let file_id = call_id.as_file(MacroFileKind::Items);
                            if let Some(item_list) =
                                db.parse_or_expand(file_id).and_then(ast::MacroItems::cast)
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
index 6c4e8ffbd..e1780ed38 100644
--- a/crates/ra_hir/src/lang_item.rs
+++ b/crates/ra_hir/src/lang_item.rs
@@ -22,14 +22,14 @@ pub enum LangItemTarget {
 impl LangItemTarget {
    pub(crate) fn krate(&self, db: &impl HirDatabase) -> Option<Crate> {
-        match self {
+        Some(match self {
-            LangItemTarget::Enum(e) => e.module(db).krate(db),
+            LangItemTarget::Enum(e) => e.module(db).krate(),
-            LangItemTarget::Function(f) => f.module(db).krate(db),
+            LangItemTarget::Function(f) => f.module(db).krate(),
-            LangItemTarget::ImplBlock(i) => i.module().krate(db),
+            LangItemTarget::ImplBlock(i) => i.module().krate(),
-            LangItemTarget::Static(s) => s.module(db).krate(db),
+            LangItemTarget::Static(s) => s.module(db).krate(),
-            LangItemTarget::Struct(s) => s.module(db).krate(db),
+            LangItemTarget::Struct(s) => s.module(db).krate(),
-            LangItemTarget::Trait(t) => t.module(db).krate(db),
+            LangItemTarget::Trait(t) => t.module(db).krate(),
-        }
+        })
    }
 }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index ca261e8f5..40f5562b4 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -26,25 +26,19 @@ macro_rules! impl_froms {
    }
 }
-mod either;
 pub mod debug;
 pub mod db;
 #[macro_use]
 pub mod mock;
-mod path;
 pub mod source_binder;
-mod source_id;
 mod ids;
-mod name;
 mod nameres;
 mod adt;
 mod traits;
 mod type_alias;
-mod type_ref;
 mod ty;
-mod attr;
 mod impl_block;
 mod expr;
 mod lang_item;
@@ -60,37 +54,35 @@ pub mod from_source;
 #[cfg(test)]
 mod marks;
-use crate::{
+use hir_expand::AstId;
-    ids::MacroFileKind,
-    name::AsName,
+use crate::{ids::MacroFileKind, resolve::Resolver};
-    resolve::Resolver,
-    source_id::{AstId, FileAstId},
-};
-pub use self::{
+pub use crate::{
    adt::VariantDef,
-    either::Either,
+    code_model::{
+        docs::{DocDef, Docs, Documentation},
+        src::{HasBodySource, HasSource, Source},
+        Adt, AssocItem, Const, ConstData, Container, Crate, CrateDependency, DefWithBody, Enum,
+        EnumVariant, FieldSource, FnData, Function, HasBody, MacroDef, Module, ModuleDef,
+        ModuleSource, Static, Struct, StructField, Trait, TypeAlias, Union,
+    },
    expr::ExprScopes,
    from_source::FromSource,
    generics::{GenericDef, GenericParam, GenericParams, HasGenericParams},
    ids::{HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFile},
    impl_block::ImplBlock,
-    name::Name,
    nameres::{ImportId, Namespace, PerNs},
-    path::{Path, PathKind},
    resolve::ScopeDef,
    source_binder::{PathResolution, ScopeEntryWithSyntax, SourceAnalyzer},
-    source_id::{AstIdMap, ErasedFileAstId},
    ty::{
        display::HirDisplay, ApplicationTy, CallableDef, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
    },
-    type_ref::Mutability,
 };
-pub use self::code_model::{
+pub use hir_def::{
-    docs::{DocDef, Docs, Documentation},
+    builtin_type::BuiltinType,
-    src::{HasBodySource, HasSource, Source},
+    path::{Path, PathKind},
-    Adt, AssocItem, BuiltinType, Const, ConstData, Container, Crate, CrateDependency, DefWithBody,
+    type_ref::Mutability,
-    Enum, EnumVariant, FieldSource, FnData, Function, HasBody, MacroDef, Module, ModuleDef,
-    ModuleSource, Static, Struct, StructField, Trait, TypeAlias, Union,
 };
+pub use hir_expand::{either::Either, name::Name};
diff --git a/crates/ra_hir/src/marks.rs b/crates/ra_hir/src/marks.rs
index 79af24b20..b423489a1 100644
--- a/crates/ra_hir/src/marks.rs
+++ b/crates/ra_hir/src/marks.rs
@@ -2,6 +2,7 @@
 test_utils::marks!(
    bogus_paths
+    // FIXME: restore this mark once hir is split
    name_res_works_for_broken_modules
    can_import_enum_variant
    type_var_cycles_resolve_completely
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 0b278deb3..35dfaf3ba 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -22,6 +22,7 @@ pub const WORKSPACE: SourceRootId = SourceRootId(0);
    db::InternDatabaseStorage,
    db::AstDatabaseStorage,
    db::DefDatabaseStorage,
+    db::DefDatabase2Storage,
    db::HirDatabaseStorage
 )]
 #[derive(Debug)]
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 67adcfa28..7ba031827 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -48,16 +48,15 @@
 //! on the result
 mod per_ns;
-mod raw;
 mod collector;
-mod mod_resolution;
 #[cfg(test)]
 mod tests;
 use std::sync::Arc;
+use hir_def::{builtin_type::BuiltinType, CrateModuleId};
 use once_cell::sync::Lazy;
-use ra_arena::{impl_arena_id, Arena, RawId};
+use ra_arena::Arena;
 use ra_db::{Edition, FileId};
 use ra_prof::profile;
 use ra_syntax::ast;
@@ -69,16 +68,12 @@ use crate::{
    diagnostics::DiagnosticSink,
    ids::MacroDefId,
    nameres::diagnostics::DefDiagnostic,
-    Adt, AstId, BuiltinType, Crate, HirFileId, MacroDef, Module, ModuleDef, Name, Path, PathKind,
+    Adt, AstId, Crate, HirFileId, MacroDef, Module, ModuleDef, Name, Path, PathKind, Trait,
-    Trait,
 };
-pub(crate) use self::raw::{ImportSourceMap, RawItems};
+pub use self::per_ns::{Namespace, PerNs};
-pub use self::{
+pub use hir_def::nameres::raw::ImportId;
-    per_ns::{Namespace, PerNs},
-    raw::ImportId,
-};
 /// Contains all top-level defs from a macro-expanded crate
 #[derive(Debug, PartialEq, Eq)]
@@ -115,13 +110,8 @@ impl std::ops::Index<CrateModuleId> for CrateDefMap {
    }
 }
-/// An ID of a module, **local** to a specific crate
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub(crate) struct CrateModuleId(RawId);
-impl_arena_id!(CrateModuleId);
 #[derive(Default, Debug, PartialEq, Eq)]
-pub(crate) struct ModuleData {
+pub struct ModuleData {
    pub(crate) parent: Option<CrateModuleId>,
    pub(crate) children: FxHashMap<Name, CrateModuleId>,
    pub(crate) scope: ModuleScope,
@@ -332,10 +322,11 @@ impl CrateDefMap {
    ) -> ResolvePathResult {
        let mut segments = path.segments.iter().enumerate();
        let mut curr_per_ns: PerNs = match path.kind {
-            PathKind::DollarCrate(krate) => {
+            PathKind::DollarCrate(crate_id) => {
+                let krate = Crate { crate_id };
                if krate == self.krate {
                    tested_by!(macro_dollar_crate_self);
-                    PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+                    PerNs::types(Module::new(self.krate, self.root).into())
                } else {
                    match krate.root_module(db) {
                        Some(module) => {
@@ -346,12 +337,8 @@ impl CrateDefMap {
                    }
                }
            }
-            PathKind::Crate => {
+            PathKind::Crate => PerNs::types(Module::new(self.krate, self.root).into()),
-                PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+            PathKind::Self_ => PerNs::types(Module::new(self.krate, original_module).into()),
-            }
-            PathKind::Self_ => {
-                PerNs::types(Module { krate: self.krate, module_id: original_module }.into())
-            }
            // plain import or absolute path in 2015: crate-relative with
            // fallback to extern prelude (with the simplification in
            // rust-lang/rust#57745)
@@ -377,7 +364,7 @@ impl CrateDefMap {
            }
            PathKind::Super => {
                if let Some(p) = self.modules[original_module].parent {
-                    PerNs::types(Module { krate: self.krate, module_id: p }.into())
+                    PerNs::types(Module::new(self.krate, p).into())
                } else {
                    log::debug!("super path in root module");
                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
@@ -419,12 +406,12 @@ impl CrateDefMap {
            curr_per_ns = match curr {
                ModuleDef::Module(module) => {
-                    if module.krate != self.krate {
+                    if module.krate() != self.krate {
                        let path =
                            Path { segments: path.segments[i..].to_vec(), kind: PathKind::Self_ };
                        log::debug!("resolving {:?} in other crate", path);
-                        let defp_map = db.crate_def_map(module.krate);
+                        let defp_map = db.crate_def_map(module.krate());
-                        let (def, s) = defp_map.resolve_path(db, module.module_id, &path);
+                        let (def, s) = defp_map.resolve_path(db, module.id.module_id, &path);
                        return ResolvePathResult::with(
                            def,
                            ReachedFixedPoint::Yes,
@@ -433,7 +420,7 @@ impl CrateDefMap {
                    }
                    // Since it is a qualified path here, it should not contains legacy macros
-                    match self[module.module_id].scope.get(&segment.name) {
+                    match self[module.id.module_id].scope.get(&segment.name) {
                        Some(res) => res.def,
                        _ => {
                            log::debug!("path segment {:?} not found", segment.name);
@@ -511,14 +498,14 @@ impl CrateDefMap {
    fn resolve_in_prelude(&self, db: &impl DefDatabase, name: &Name) -> PerNs {
        if let Some(prelude) = self.prelude {
            let keep;
-            let def_map = if prelude.krate == self.krate {
+            let def_map = if prelude.krate() == self.krate {
                self
            } else {
                // Extend lifetime
-                keep = db.crate_def_map(prelude.krate);
+                keep = db.crate_def_map(prelude.krate());
                &keep
            };
-            def_map[prelude.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
+            def_map[prelude.id.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
        } else {
            PerNs::none()
        }
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index b5fe16bfa..ee0a4c99f 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -1,5 +1,10 @@
 //! FIXME: write short doc here
+use hir_def::{
+    attr::Attr,
+    nameres::{mod_resolution::ModDir, raw},
+};
+use hir_expand::name;
 use ra_cfg::CfgOptions;
 use ra_db::FileId;
 use ra_syntax::{ast, SmolStr};
@@ -7,13 +12,11 @@ use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 use crate::{
-    attr::Attr,
    db::DefDatabase,
    ids::{AstItemDef, LocationCtx, MacroCallId, MacroCallLoc, MacroDefId, MacroFileKind},
-    name::MACRO_RULES,
    nameres::{
-        diagnostics::DefDiagnostic, mod_resolution::ModDir, raw, Crate, CrateDefMap, CrateModuleId,
+        diagnostics::DefDiagnostic, Crate, CrateDefMap, CrateModuleId, ModuleData, ModuleDef,
-        ModuleData, ModuleDef, PerNs, ReachedFixedPoint, Resolution, ResolveMode,
+        PerNs, ReachedFixedPoint, Resolution, ResolveMode,
    },
    Adt, AstId, Const, Enum, Function, HirFileId, MacroDef, Module, Name, Path, PathKind, Static,
    Struct, Trait, TypeAlias, Union,
@@ -212,7 +215,7 @@ where
        if let Some(ModuleDef::Module(m)) = res.take_types() {
            tested_by!(macro_rules_from_other_crates_are_visible_with_macro_use);
-            self.import_all_macros_exported(current_module_id, m.krate);
+            self.import_all_macros_exported(current_module_id, m.krate());
        }
    }
@@ -289,11 +292,11 @@ where
                    if import.is_prelude {
                        tested_by!(std_prelude);
                        self.def_map.prelude = Some(m);
-                    } else if m.krate != self.def_map.krate {
+                    } else if m.krate() != self.def_map.krate {
                        tested_by!(glob_across_crates);
                        // glob import from other crate => we can just import everything once
-                        let item_map = self.db.crate_def_map(m.krate);
+                        let item_map = self.db.crate_def_map(m.krate());
-                        let scope = &item_map[m.module_id].scope;
+                        let scope = &item_map[m.id.module_id].scope;
                        // Module scoped macros is included
                        let items = scope
@@ -307,7 +310,7 @@ where
                        // glob import from same crate => we do an initial
                        // import, and then need to propagate any further
                        // additions
-                        let scope = &self.def_map[m.module_id].scope;
+                        let scope = &self.def_map[m.id.module_id].scope;
                        // Module scoped macros is included
                        let items = scope
@@ -319,7 +322,7 @@ where
                        self.update(module_id, Some(import_id), &items);
                        // record the glob import in case we add further items
                        self.glob_imports
-                            .entry(m.module_id)
+                            .entry(m.id.module_id)
                            .or_default()
                            .push((module_id, import_id));
                    }
@@ -448,7 +451,7 @@ where
            );
            if let Some(def) = resolved_res.resolved_def.get_macros() {
-                let call_id = MacroCallLoc { def: def.id, ast_id: *ast_id }.id(self.db);
+                let call_id = self.db.intern_macro(MacroCallLoc { def: def.id, ast_id: *ast_id });
                resolved.push((*module_id, call_id, def.id));
                res = ReachedFixedPoint::No;
                return false;
@@ -523,9 +526,10 @@ where
        // Prelude module is always considered to be `#[macro_use]`.
        if let Some(prelude_module) = self.def_collector.def_map.prelude {
-            if prelude_module.krate != self.def_collector.def_map.krate {
+            if prelude_module.krate() != self.def_collector.def_map.krate {
                tested_by!(prelude_is_macro_use);
-                self.def_collector.import_all_macros_exported(self.module_id, prelude_module.krate);
+                self.def_collector
+                    .import_all_macros_exported(self.module_id, prelude_module.krate());
            }
        }
@@ -567,7 +571,7 @@ where
            // inline module, just recurse
            raw::ModuleData::Definition { name, items, ast_id } => {
                let module_id =
-                    self.push_child_module(name.clone(), ast_id.with_file_id(self.file_id), None);
+                    self.push_child_module(name.clone(), AstId::new(self.file_id, *ast_id), None);
                ModCollector {
                    def_collector: &mut *self.def_collector,
@@ -583,7 +587,7 @@ where
            }
            // out of line module, resolve, parse and recurse
            raw::ModuleData::Declaration { name, ast_id } => {
-                let ast_id = ast_id.with_file_id(self.file_id);
+                let ast_id = AstId::new(self.file_id, *ast_id);
                match self.mod_dir.resolve_declaration(
                    self.def_collector.db,
                    self.file_id,
@@ -631,9 +635,7 @@ where
        modules[res].scope.legacy_macros = modules[self.module_id].scope.legacy_macros.clone();
        modules[self.module_id].children.insert(name.clone(), res);
        let resolution = Resolution {
-            def: PerNs::types(
+            def: PerNs::types(Module::new(self.def_collector.def_map.krate, res).into()),
-                Module { krate: self.def_collector.def_map.krate, module_id: res }.into(),
-            ),
            import: None,
        };
        self.def_collector.update(self.module_id, None, &[(name, resolution)]);
@@ -641,8 +643,8 @@ where
    }
    fn define_def(&mut self, def: &raw::DefData) {
-        let module = Module { krate: self.def_collector.def_map.krate, module_id: self.module_id };
+        let module = Module::new(self.def_collector.def_map.krate, self.module_id);
-        let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id);
+        let ctx = LocationCtx::new(self.def_collector.db, module.id, self.file_id);
        macro_rules! def {
            ($kind:ident, $ast_id:ident) => {
@@ -671,28 +673,26 @@ where
    }
    fn collect_macro(&mut self, mac: &raw::MacroData) {
+        let ast_id = AstId::new(self.file_id, mac.ast_id);
        // Case 1: macro rules, define a macro in crate-global mutable scope
        if is_macro_rules(&mac.path) {
            if let Some(name) = &mac.name {
-                let macro_id = MacroDefId {
+                let macro_id =
-                    ast_id: mac.ast_id.with_file_id(self.file_id),
+                    MacroDefId { ast_id, krate: self.def_collector.def_map.krate.crate_id };
-                    krate: self.def_collector.def_map.krate,
-                };
                let macro_ = MacroDef { id: macro_id };
                self.def_collector.define_macro(self.module_id, name.clone(), macro_, mac.export);
            }
            return;
        }
-        let ast_id = mac.ast_id.with_file_id(self.file_id);
        // Case 2: try to resolve in legacy scope and expand macro_rules, triggering
        // recursive item collection.
        if let Some(macro_def) = mac.path.as_ident().and_then(|name| {
            self.def_collector.def_map[self.module_id].scope.get_legacy_macro(&name)
        }) {
            let def = macro_def.id;
-            let macro_call_id = MacroCallLoc { def, ast_id }.id(self.def_collector.db);
+            let macro_call_id = self.def_collector.db.intern_macro(MacroCallLoc { def, ast_id });
            self.def_collector.collect_macro_expansion(self.module_id, macro_call_id, def);
            return;
@@ -728,7 +728,7 @@ where
 }
 fn is_macro_rules(path: &Path) -> bool {
-    path.as_ident() == Some(&MACRO_RULES)
+    path.as_ident() == Some(&name::MACRO_RULES)
 }
 #[cfg(test)]
diff --git a/crates/ra_hir/src/nameres/tests/mod_resolution.rs b/crates/ra_hir/src/nameres/tests/mod_resolution.rs
index f569aacdc..abfe8b1c3 100644
--- a/crates/ra_hir/src/nameres/tests/mod_resolution.rs
+++ b/crates/ra_hir/src/nameres/tests/mod_resolution.rs
@@ -2,7 +2,7 @@ use super::*;
 #[test]
 fn name_res_works_for_broken_modules() {
-    covers!(name_res_works_for_broken_modules);
+    // covers!(name_res_works_for_broken_modules);
    let map = def_map(
        "
        //- /lib.rs
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index 3c797c0c3..75b24d386 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -1,6 +1,12 @@
 //! Name resolution.
 use std::sync::Arc;
+use hir_def::{
+    builtin_type::BuiltinType,
+    path::{Path, PathKind},
+    CrateModuleId,
+};
+use hir_expand::name::{self, Name};
 use rustc_hash::FxHashSet;
 use crate::{
@@ -12,11 +18,8 @@ use crate::{
    },
    generics::GenericParams,
    impl_block::ImplBlock,
-    name::{Name, SELF_PARAM, SELF_TYPE},
+    nameres::{CrateDefMap, PerNs},
-    nameres::{CrateDefMap, CrateModuleId, PerNs},
+    Adt, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, Static, Struct, Trait, TypeAlias,
-    path::{Path, PathKind},
-    Adt, BuiltinType, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, Static, Struct,
-    Trait, TypeAlias,
 };
 #[derive(Debug, Clone, Default)]
@@ -149,13 +152,13 @@ impl Resolver {
                    }
                }
                Scope::ImplBlockScope(impl_) => {
-                    if first_name == &SELF_TYPE {
+                    if first_name == &name::SELF_TYPE {
                        let idx = if path.segments.len() == 1 { None } else { Some(1) };
                        return Some((TypeNs::SelfType(*impl_), idx));
                    }
                }
                Scope::AdtScope(adt) => {
-                    if first_name == &SELF_TYPE {
+                    if first_name == &name::SELF_TYPE {
                        let idx = if path.segments.len() == 1 { None } else { Some(1) };
                        return Some((TypeNs::AdtSelfType(*adt), idx));
                    }
@@ -204,7 +207,7 @@ impl Resolver {
            return None;
        }
        let n_segments = path.segments.len();
-        let tmp = SELF_PARAM;
+        let tmp = name::SELF_PARAM;
        let first_name = if path.is_self() { &tmp } else { &path.segments.first()?.name };
        let skip_to_mod = path.kind != PathKind::Plain && !path.is_self();
        for scope in self.scopes.iter().rev() {
@@ -240,13 +243,13 @@ impl Resolver {
                Scope::GenericParams(_) => continue,
                Scope::ImplBlockScope(impl_) if n_segments > 1 => {
-                    if first_name == &SELF_TYPE {
+                    if first_name == &name::SELF_TYPE {
                        let ty = TypeNs::SelfType(*impl_);
                        return Some(ResolveValueResult::Partial(ty, 1));
                    }
                }
                Scope::AdtScope(adt) if n_segments > 1 => {
-                    if first_name == &SELF_TYPE {
+                    if first_name == &name::SELF_TYPE {
                        let ty = TypeNs::AdtSelfType(*adt);
                        return Some(ResolveValueResult::Partial(ty, 1));
                    }
@@ -330,8 +333,8 @@ impl Resolver {
        for scope in &self.scopes {
            if let Scope::ModuleScope(m) = scope {
                if let Some(prelude) = m.crate_def_map.prelude() {
-                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
-                    traits.extend(prelude_def_map[prelude.module_id].scope.traits());
+                    traits.extend(prelude_def_map[prelude.id.module_id].scope.traits());
                }
                traits.extend(m.crate_def_map[m.module_id].scope.traits());
            }
@@ -444,10 +447,12 @@ impl Scope {
                    f(name.clone(), ScopeDef::ModuleDef(*def));
                });
                if let Some(prelude) = m.crate_def_map.prelude() {
-                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    let prelude_def_map = db.crate_def_map(prelude.krate());
-                    prelude_def_map[prelude.module_id].scope.entries().for_each(|(name, res)| {
+                    prelude_def_map[prelude.id.module_id].scope.entries().for_each(
-                        f(name.clone(), res.def.into());
+                        |(name, res)| {
-                    });
+                            f(name.clone(), res.def.into());
+                        },
+                    );
                }
            }
            Scope::GenericParams(gp) => {
@@ -456,10 +461,10 @@ impl Scope {
                }
            }
            Scope::ImplBlockScope(i) => {
-                f(SELF_TYPE, ScopeDef::ImplSelfType(*i));
+                f(name::SELF_TYPE, ScopeDef::ImplSelfType(*i));
            }
            Scope::AdtScope(i) => {
-                f(SELF_TYPE, ScopeDef::AdtSelfType(*i));
+                f(name::SELF_TYPE, ScopeDef::AdtSelfType(*i));
            }
            Scope::ExprScope(e) => {
                e.expr_scopes.entries(e.scope_id).iter().for_each(|e| {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index a907d6a9f..152bc71bd 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -7,10 +7,12 @@
 //! purely for "IDE needs".
 use std::sync::Arc;
+use hir_def::path::known;
+use hir_expand::name::AsName;
 use ra_db::FileId;
 use ra_syntax::{
    ast::{self, AstNode},
-    AstPtr,
+    match_ast, AstPtr,
    SyntaxKind::*,
    SyntaxNode, SyntaxNodePtr, TextRange, TextUnit,
 };
@@ -24,11 +26,10 @@ use crate::{
        BodySourceMap,
    },
    ids::LocationCtx,
-    path::known,
    resolve::{ScopeDef, TypeNs, ValueNs},
    ty::method_resolution::implements_trait,
-    AsName, Const, DefWithBody, Either, Enum, FromSource, Function, HasBody, HirFileId, MacroDef,
+    Const, DefWithBody, Either, Enum, FromSource, Function, HasBody, HirFileId, MacroDef, Module,
-    Module, Name, Path, Resolver, Static, Struct, Ty,
+    Name, Path, Resolver, Static, Struct, Ty,
 };
 fn try_get_resolver_for_node(
@@ -36,24 +37,34 @@ fn try_get_resolver_for_node(
    file_id: FileId,
    node: &SyntaxNode,
 ) -> Option<Resolver> {
-    if let Some(module) = ast::Module::cast(node.clone()) {
+    match_ast! {
-        let src = crate::Source { file_id: file_id.into(), ast: module };
+        match node {
-        Some(crate::Module::from_declaration(db, src)?.resolver(db))
+            ast::Module(it) => {
-    } else if let Some(file) = ast::SourceFile::cast(node.clone()) {
+                let src = crate::Source { file_id: file_id.into(), ast: it };
-        let src =
+                Some(crate::Module::from_declaration(db, src)?.resolver(db))
-            crate::Source { file_id: file_id.into(), ast: crate::ModuleSource::SourceFile(file) };
+            },
-        Some(crate::Module::from_definition(db, src)?.resolver(db))
+             ast::SourceFile(it) => {
-    } else if let Some(s) = ast::StructDef::cast(node.clone()) {
+                let src =
-        let src = crate::Source { file_id: file_id.into(), ast: s };
+                    crate::Source { file_id: file_id.into(), ast: crate::ModuleSource::SourceFile(it) };
-        Some(Struct::from_source(db, src)?.resolver(db))
+                Some(crate::Module::from_definition(db, src)?.resolver(db))
-    } else if let Some(e) = ast::EnumDef::cast(node.clone()) {
+            },
-        let src = crate::Source { file_id: file_id.into(), ast: e };
+            ast::StructDef(it) => {
-        Some(Enum::from_source(db, src)?.resolver(db))
+                let src = crate::Source { file_id: file_id.into(), ast: it };
-    } else if node.kind() == FN_DEF || node.kind() == CONST_DEF || node.kind() == STATIC_DEF {
+                Some(Struct::from_source(db, src)?.resolver(db))
-        Some(def_with_body_from_child_node(db, file_id, node)?.resolver(db))
+            },
-    } else {
+            ast::EnumDef(it) => {
-        // FIXME add missing cases
+                let src = crate::Source { file_id: file_id.into(), ast: it };
-        None
+                Some(Enum::from_source(db, src)?.resolver(db))
+            },
+            _ => {
+                if node.kind() == FN_DEF || node.kind() == CONST_DEF || node.kind() == STATIC_DEF {
+                    Some(def_with_body_from_child_node(db, file_id, node)?.resolver(db))
+                } else {
+                    // FIXME add missing cases
+                    None
+                }
+            },
+        }
    }
 }
@@ -64,19 +75,17 @@ fn def_with_body_from_child_node(
 ) -> Option<DefWithBody> {
    let src = crate::ModuleSource::from_child_node(db, file_id, node);
    let module = Module::from_definition(db, crate::Source { file_id: file_id.into(), ast: src })?;
-    let ctx = LocationCtx::new(db, module, file_id.into());
+    let ctx = LocationCtx::new(db, module.id, file_id.into());
    node.ancestors().find_map(|node| {
-        if let Some(def) = ast::FnDef::cast(node.clone()) {
+        match_ast! {
-            return Some(Function { id: ctx.to_def(&def) }.into());
+            match node {
-        }
+                ast::FnDef(def)  => { Some(Function {id: ctx.to_def(&def) }.into()) },
-        if let Some(def) = ast::ConstDef::cast(node.clone()) {
+                ast::ConstDef(def) => { Some(Const { id: ctx.to_def(&def) }.into()) },
-            return Some(Const { id: ctx.to_def(&def) }.into());
+                ast::StaticDef(def) => { Some(Static { id: ctx.to_def(&def) }.into()) },
-        }
+                _ => { None },
-        if let Some(def) = ast::StaticDef::cast(node) {
+            }
-            return Some(Static { id: ctx.to_def(&def) }.into());
        }
-        None
    })
 }
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
index e39511518..1a45dacba 100644
--- a/crates/ra_hir/src/traits.rs
+++ b/crates/ra_hir/src/traits.rs
@@ -1,14 +1,15 @@
 //! HIR for trait definitions.
-use rustc_hash::FxHashMap;
 use std::sync::Arc;
+use hir_expand::name::AsName;
 use ra_syntax::ast::{self, NameOwner};
+use rustc_hash::FxHashMap;
 use crate::{
    db::{AstDatabase, DefDatabase},
    ids::LocationCtx,
-    name::AsName,
    AssocItem, Const, Function, HasSource, Module, Name, Trait, TypeAlias,
 };
@@ -27,7 +28,7 @@ impl TraitData {
        let src = tr.source(db);
        let name = src.ast.name().map(|n| n.as_name());
        let module = tr.module(db);
-        let ctx = LocationCtx::new(db, module, src.file_id);
+        let ctx = LocationCtx::new(db, module.id, src.file_id);
        let auto = src.ast.is_auto();
        let items = if let Some(item_list) = src.ast.item_list() {
            item_list
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index cc9746f6d..d2bfcdc7d 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -17,8 +17,8 @@ use std::sync::Arc;
 use std::{fmt, iter, mem};
 use crate::{
-    db::HirDatabase, expr::ExprId, type_ref::Mutability, util::make_mut_slice, Adt, Crate,
+    db::HirDatabase, expr::ExprId, util::make_mut_slice, Adt, Crate, DefWithBody, GenericParams,
-    DefWithBody, GenericParams, HasGenericParams, Name, Trait, TypeAlias,
+    HasGenericParams, Mutability, Name, Trait, TypeAlias,
 };
 use display::{HirDisplay, HirFormatter};
diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index 02492ca14..3645ee831 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -5,10 +5,11 @@
 use std::iter::successors;
+use hir_expand::name;
 use log::{info, warn};
 use super::{traits::Solution, Canonical, Substs, Ty, TypeWalk};
-use crate::{db::HirDatabase, name, HasGenericParams, Resolver};
+use crate::{db::HirDatabase, HasGenericParams, Resolver};
 const AUTODEREF_RECURSION_LIMIT: usize = 10;
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index ebaff998e..6694467a3 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -21,6 +21,11 @@ use std::sync::Arc;
 use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
 use rustc_hash::FxHashMap;
+use hir_def::{
+    path::known,
+    type_ref::{Mutability, TypeRef},
+};
+use hir_expand::name;
 use ra_arena::map::ArenaMap;
 use ra_prof::profile;
 use test_utils::tested_by;
@@ -37,11 +42,8 @@ use crate::{
    db::HirDatabase,
    diagnostics::DiagnosticSink,
    expr::{BindingAnnotation, Body, ExprId, PatId},
-    name,
-    path::known,
    resolve::{Resolver, TypeNs},
    ty::infer::diagnostics::InferenceDiagnostic,
-    type_ref::{Mutability, TypeRef},
    Adt, AssocItem, ConstData, DefWithBody, FnData, Function, HasBody, Path, StructField,
 };
diff --git a/crates/ra_hir/src/ty/infer/coerce.rs b/crates/ra_hir/src/ty/infer/coerce.rs
index 0429a9866..6ea135126 100644
--- a/crates/ra_hir/src/ty/infer/coerce.rs
+++ b/crates/ra_hir/src/ty/infer/coerce.rs
@@ -14,8 +14,7 @@ use crate::{
    lang_item::LangItemTarget,
    resolve::Resolver,
    ty::{autoderef, Substs, Ty, TypeCtor, TypeWalk},
-    type_ref::Mutability,
+    Adt, Mutability,
-    Adt,
 };
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
index f8807c742..fed52df39 100644
--- a/crates/ra_hir/src/ty/infer/expr.rs
+++ b/crates/ra_hir/src/ty/infer/expr.rs
@@ -3,14 +3,15 @@
 use std::iter::{repeat, repeat_with};
 use std::sync::Arc;
+use hir_def::path::{GenericArg, GenericArgs};
+use hir_expand::name;
 use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
 use crate::{
    db::HirDatabase,
    expr::{self, Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
    generics::{GenericParams, HasGenericParams},
-    name,
    nameres::Namespace,
-    path::{GenericArg, GenericArgs},
    ty::{
        autoderef, method_resolution, op, primitive, CallableDef, InferTy, Mutability, Obligation,
        ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
diff --git a/crates/ra_hir/src/ty/infer/path.rs b/crates/ra_hir/src/ty/infer/path.rs
index db979353a..77aa35ce1 100644
--- a/crates/ra_hir/src/ty/infer/path.rs
+++ b/crates/ra_hir/src/ty/infer/path.rs
@@ -1,5 +1,7 @@
 //! Path expression resolution.
+use hir_def::path::PathSegment;
 use super::{ExprOrPatId, InferenceContext, TraitRef};
 use crate::{
    db::HirDatabase,
@@ -131,7 +133,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
    fn resolve_trait_assoc_item(
        &mut self,
        trait_ref: TraitRef,
-        segment: &crate::path::PathSegment,
+        segment: &PathSegment,
        id: ExprOrPatId,
    ) -> Option<(ValueNs, Option<Substs>)> {
        let trait_ = trait_ref.trait_;
@@ -170,7 +172,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
    fn resolve_ty_assoc_item(
        &mut self,
        ty: Ty,
-        segment: &crate::path::PathSegment,
+        segment: &PathSegment,
        id: ExprOrPatId,
    ) -> Option<(ValueNs, Option<Substs>)> {
        if let Ty::Unknown = ty {
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 366556134..dd7cd979f 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -8,6 +8,12 @@
 use std::iter;
 use std::sync::Arc;
+use hir_def::{
+    builtin_type::BuiltinType,
+    path::{GenericArg, PathSegment},
+    type_ref::{TypeBound, TypeRef},
+};
 use super::{
    FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
    TypeWalk,
@@ -18,13 +24,14 @@ use crate::{
    generics::HasGenericParams,
    generics::{GenericDef, WherePredicate},
    nameres::Namespace,
-    path::{GenericArg, PathSegment},
    resolve::{Resolver, TypeNs},
-    ty::Adt,
+    ty::{
-    type_ref::{TypeBound, TypeRef},
+        primitive::{FloatTy, IntTy},
+        Adt,
+    },
    util::make_mut_slice,
-    BuiltinType, Const, Enum, EnumVariant, Function, ModuleDef, Path, Static, Struct, StructField,
+    Const, Enum, EnumVariant, Function, ModuleDef, Path, Static, Struct, StructField, Trait,
-    Trait, TypeAlias, Union,
+    TypeAlias, Union,
 };
 impl Ty {
@@ -640,8 +647,10 @@ fn type_for_builtin(def: BuiltinType) -> Ty {
        BuiltinType::Char => TypeCtor::Char,
        BuiltinType::Bool => TypeCtor::Bool,
        BuiltinType::Str => TypeCtor::Str,
-        BuiltinType::Int(ty) => TypeCtor::Int(ty.into()),
+        BuiltinType::Int { signedness, bitness } => {
-        BuiltinType::Float(ty) => TypeCtor::Float(ty.into()),
+            TypeCtor::Int(IntTy { signedness, bitness }.into())
+        }
+        BuiltinType::Float { bitness } => TypeCtor::Float(FloatTy { bitness }.into()),
    })
 }
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index ad2ab560d..eb69344f6 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -5,18 +5,17 @@
 use std::sync::Arc;
 use arrayvec::ArrayVec;
+use hir_def::CrateModuleId;
 use rustc_hash::FxHashMap;
 use super::{autoderef, lower, Canonical, InEnvironment, TraitEnvironment, TraitRef};
 use crate::{
    db::HirDatabase,
    impl_block::{ImplBlock, ImplId},
-    nameres::CrateModuleId,
    resolve::Resolver,
    ty::primitive::{FloatBitness, UncertainFloatTy, UncertainIntTy},
    ty::{Ty, TypeCtor},
-    type_ref::Mutability,
+    AssocItem, Crate, Function, Module, Mutability, Name, Trait,
-    AssocItem, Crate, Function, Module, Name, Trait,
 };
 /// This is used as a key for indexing impls.
@@ -50,7 +49,7 @@ impl CrateImplBlocks {
        let fingerprint = TyFingerprint::for_impl(ty);
        fingerprint.and_then(|f| self.impls.get(&f)).into_iter().flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -62,7 +61,7 @@ impl CrateImplBlocks {
    ) -> impl Iterator<Item = ImplBlock> + 'a {
        self.impls_by_trait.get(&tr).into_iter().flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -71,7 +70,7 @@ impl CrateImplBlocks {
    pub fn all_impls<'a>(&'a self) -> impl Iterator<Item = ImplBlock> + 'a {
        self.impls.values().chain(self.impls_by_trait.values()).flat_map(|i| i.iter()).map(
            move |(module_id, impl_id)| {
-                let module = Module { krate: self.krate, module_id: *module_id };
+                let module = Module::new(self.krate, *module_id);
                ImplBlock::from_id(module, *impl_id)
            },
        )
@@ -90,14 +89,14 @@ impl CrateImplBlocks {
                    self.impls_by_trait
                        .entry(tr.trait_)
                        .or_insert_with(Vec::new)
-                        .push((module.module_id, impl_id));
+                        .push((module.id.module_id, impl_id));
                }
            } else {
                if let Some(target_ty_fp) = TyFingerprint::for_impl(&target_ty) {
                    self.impls
                        .entry(target_ty_fp)
                        .or_insert_with(Vec::new)
-                        .push((module.module_id, impl_id));
+                        .push((module.id.module_id, impl_id));
                }
            }
        }
diff --git a/crates/ra_hir/src/ty/primitive.rs b/crates/ra_hir/src/ty/primitive.rs
index 8966f9d1d..1749752f1 100644
--- a/crates/ra_hir/src/ty/primitive.rs
+++ b/crates/ra_hir/src/ty/primitive.rs
@@ -2,27 +2,7 @@
 use std::fmt;
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub use hir_def::builtin_type::{FloatBitness, IntBitness, Signedness};
-pub enum Signedness {
-    Signed,
-    Unsigned,
-}
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub enum IntBitness {
-    Xsize,
-    X8,
-    X16,
-    X32,
-    X64,
-    X128,
-}
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub enum FloatBitness {
-    X32,
-    X64,
-}
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum UncertainIntTy {
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index 0cb5c3798..4f1eab150 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -1,7 +1,7 @@
 //! Trait solving using Chalk.
 use std::sync::{Arc, Mutex};
-use chalk_ir::cast::Cast;
+use chalk_ir::{cast::Cast, family::ChalkIr};
 use log::debug;
 use ra_db::salsa;
 use ra_prof::profile;
@@ -33,7 +33,7 @@ impl TraitSolver {
    fn solve(
        &self,
        db: &impl HirDatabase,
-        goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal>>,
+        goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal<ChalkIr>>>,
    ) -> Option<chalk_solve::Solution> {
        let context = ChalkContext { db, krate: self.krate };
        debug!("solve goal: {:?}", goal);
@@ -196,7 +196,7 @@ pub(crate) fn trait_solve_query(
 }
 fn solution_from_chalk(db: &impl HirDatabase, solution: chalk_solve::Solution) -> Solution {
-    let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution>| {
+    let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution<ChalkIr>>| {
        let value = subst
            .value
            .parameters
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 00aaf65d9..39ef92182 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -4,11 +4,13 @@ use std::sync::Arc;
 use log::debug;
 use chalk_ir::{
-    cast::Cast, Identifier, ImplId, Parameter, PlaceholderIndex, TypeId, TypeKindId, TypeName,
+    cast::Cast, family::ChalkIr, Identifier, ImplId, Parameter, PlaceholderIndex, TypeId,
-    UniverseIndex,
+    TypeKindId, TypeName, UniverseIndex,
 };
 use chalk_rust_ir::{AssociatedTyDatum, ImplDatum, StructDatum, TraitDatum};
+use hir_expand::name;
 use ra_db::salsa::{InternId, InternKey};
 use super::{Canonical, ChalkContext, Impl, Obligation};
@@ -38,8 +40,8 @@ where
 }
 impl ToChalk for Ty {
-    type Chalk = chalk_ir::Ty;
+    type Chalk = chalk_ir::Ty<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Ty {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Ty<ChalkIr> {
        match self {
            Ty::Apply(apply_ty) => {
                let name = match apply_ty.ctor {
@@ -62,21 +64,19 @@ impl ToChalk for Ty {
                chalk_ir::ProjectionTy { associated_ty_id, parameters }.cast()
            }
            Ty::Param { idx, .. } => {
-                PlaceholderIndex { ui: UniverseIndex::ROOT, idx: idx as usize }.to_ty()
+                PlaceholderIndex { ui: UniverseIndex::ROOT, idx: idx as usize }.to_ty::<ChalkIr>()
            }
            Ty::Bound(idx) => chalk_ir::Ty::BoundVar(idx as usize),
            Ty::Infer(_infer_ty) => panic!("uncanonicalized infer ty"),
-            // FIXME this is clearly incorrect, but probably not too incorrect
+            // FIXME use Chalk's Dyn/Opaque once the bugs with that are fixed
-            // and I'm not sure what to actually do with Ty::Unknown
-            // maybe an alternative would be `for<T> T`? (meaningless in rust, but expressible in chalk's Ty)
-            //
-            // FIXME also dyn and impl Trait are currently handled like Unknown because Chalk doesn't have them yet
            Ty::Unknown | Ty::Dyn(_) | Ty::Opaque(_) => {
-                PlaceholderIndex { ui: UniverseIndex::ROOT, idx: usize::max_value() }.to_ty()
+                let parameters = Vec::new();
+                let name = TypeName::Error;
+                chalk_ir::ApplicationTy { name, parameters }.cast()
            }
        }
    }
-    fn from_chalk(db: &impl HirDatabase, chalk: chalk_ir::Ty) -> Self {
+    fn from_chalk(db: &impl HirDatabase, chalk: chalk_ir::Ty<ChalkIr>) -> Self {
        match chalk {
            chalk_ir::Ty::Apply(apply_ty) => {
                // FIXME this is kind of hacky due to the fact that
@@ -92,6 +92,7 @@ impl ToChalk for Ty {
                        let parameters = from_chalk(db, apply_ty.parameters);
                        Ty::Apply(ApplicationTy { ctor, parameters })
                    }
+                    TypeName::Error => Ty::Unknown,
                    // FIXME handle TypeKindId::Trait/Type here
                    TypeName::TypeKindId(_) => unimplemented!(),
                    TypeName::Placeholder(idx) => {
@@ -108,18 +109,30 @@ impl ToChalk for Ty {
            chalk_ir::Ty::ForAll(_) => unimplemented!(),
            chalk_ir::Ty::BoundVar(idx) => Ty::Bound(idx as u32),
            chalk_ir::Ty::InferenceVar(_iv) => Ty::Unknown,
+            chalk_ir::Ty::Dyn(where_clauses) => {
+                assert_eq!(where_clauses.binders.len(), 1);
+                let predicates =
+                    where_clauses.value.into_iter().map(|c| from_chalk(db, c)).collect();
+                Ty::Dyn(predicates)
+            }
+            chalk_ir::Ty::Opaque(where_clauses) => {
+                assert_eq!(where_clauses.binders.len(), 1);
+                let predicates =
+                    where_clauses.value.into_iter().map(|c| from_chalk(db, c)).collect();
+                Ty::Opaque(predicates)
+            }
        }
    }
 }
 impl ToChalk for Substs {
-    type Chalk = Vec<chalk_ir::Parameter>;
+    type Chalk = Vec<chalk_ir::Parameter<ChalkIr>>;
-    fn to_chalk(self, db: &impl HirDatabase) -> Vec<Parameter> {
+    fn to_chalk(self, db: &impl HirDatabase) -> Vec<Parameter<ChalkIr>> {
        self.iter().map(|ty| ty.clone().to_chalk(db).cast()).collect()
    }
-    fn from_chalk(db: &impl HirDatabase, parameters: Vec<chalk_ir::Parameter>) -> Substs {
+    fn from_chalk(db: &impl HirDatabase, parameters: Vec<chalk_ir::Parameter<ChalkIr>>) -> Substs {
        let tys = parameters
            .into_iter()
            .map(|p| match p {
@@ -132,15 +145,15 @@ impl ToChalk for Substs {
 }
 impl ToChalk for TraitRef {
-    type Chalk = chalk_ir::TraitRef;
+    type Chalk = chalk_ir::TraitRef<ChalkIr>;
-    fn to_chalk(self: TraitRef, db: &impl HirDatabase) -> chalk_ir::TraitRef {
+    fn to_chalk(self: TraitRef, db: &impl HirDatabase) -> chalk_ir::TraitRef<ChalkIr> {
        let trait_id = self.trait_.to_chalk(db);
        let parameters = self.substs.to_chalk(db);
        chalk_ir::TraitRef { trait_id, parameters }
    }
-    fn from_chalk(db: &impl HirDatabase, trait_ref: chalk_ir::TraitRef) -> Self {
+    fn from_chalk(db: &impl HirDatabase, trait_ref: chalk_ir::TraitRef<ChalkIr>) -> Self {
        let trait_ = from_chalk(db, trait_ref.trait_id);
        let substs = from_chalk(db, trait_ref.parameters);
        TraitRef { trait_, substs }
@@ -151,11 +164,11 @@ impl ToChalk for Trait {
    type Chalk = chalk_ir::TraitId;
    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TraitId {
-        self.id.into()
+        chalk_ir::TraitId(id_to_chalk(self.id))
    }
    fn from_chalk(_db: &impl HirDatabase, trait_id: chalk_ir::TraitId) -> Trait {
-        Trait { id: trait_id.into() }
+        Trait { id: id_from_chalk(trait_id.0) }
    }
 }
@@ -187,18 +200,18 @@ impl ToChalk for TypeAlias {
    type Chalk = chalk_ir::TypeId;
    fn to_chalk(self, _db: &impl HirDatabase) -> chalk_ir::TypeId {
-        self.id.into()
+        chalk_ir::TypeId(id_to_chalk(self.id))
    }
-    fn from_chalk(_db: &impl HirDatabase, impl_id: chalk_ir::TypeId) -> TypeAlias {
+    fn from_chalk(_db: &impl HirDatabase, type_alias_id: chalk_ir::TypeId) -> TypeAlias {
-        TypeAlias { id: impl_id.into() }
+        TypeAlias { id: id_from_chalk(type_alias_id.0) }
    }
 }
 impl ToChalk for GenericPredicate {
-    type Chalk = chalk_ir::QuantifiedWhereClause;
+    type Chalk = chalk_ir::QuantifiedWhereClause<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::QuantifiedWhereClause {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::QuantifiedWhereClause<ChalkIr> {
        match self {
            GenericPredicate::Implemented(trait_ref) => {
                make_binders(chalk_ir::WhereClause::Implemented(trait_ref.to_chalk(db)), 0)
@@ -221,25 +234,40 @@ impl ToChalk for GenericPredicate {
    }
    fn from_chalk(
-        _db: &impl HirDatabase,
+        db: &impl HirDatabase,
-        _where_clause: chalk_ir::QuantifiedWhereClause,
+        where_clause: chalk_ir::QuantifiedWhereClause<ChalkIr>,
    ) -> GenericPredicate {
-        // This should never need to be called
+        match where_clause.value {
-        unimplemented!()
+            chalk_ir::WhereClause::Implemented(tr) => {
+                if tr.trait_id == UNKNOWN_TRAIT {
+                    // FIXME we need an Error enum on the Chalk side to avoid this
+                    return GenericPredicate::Error;
+                }
+                GenericPredicate::Implemented(from_chalk(db, tr))
+            }
+            chalk_ir::WhereClause::ProjectionEq(projection_eq) => {
+                let projection_ty = from_chalk(db, projection_eq.projection);
+                let ty = from_chalk(db, projection_eq.ty);
+                GenericPredicate::Projection(super::ProjectionPredicate { projection_ty, ty })
+            }
+        }
    }
 }
 impl ToChalk for ProjectionTy {
-    type Chalk = chalk_ir::ProjectionTy;
+    type Chalk = chalk_ir::ProjectionTy<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::ProjectionTy {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::ProjectionTy<ChalkIr> {
        chalk_ir::ProjectionTy {
            associated_ty_id: self.associated_ty.to_chalk(db),
            parameters: self.parameters.to_chalk(db),
        }
    }
-    fn from_chalk(db: &impl HirDatabase, projection_ty: chalk_ir::ProjectionTy) -> ProjectionTy {
+    fn from_chalk(
+        db: &impl HirDatabase,
+        projection_ty: chalk_ir::ProjectionTy<ChalkIr>,
+    ) -> ProjectionTy {
        ProjectionTy {
            associated_ty: from_chalk(db, projection_ty.associated_ty_id),
            parameters: from_chalk(db, projection_ty.parameters),
@@ -248,31 +276,31 @@ impl ToChalk for ProjectionTy {
 }
 impl ToChalk for super::ProjectionPredicate {
-    type Chalk = chalk_ir::Normalize;
+    type Chalk = chalk_ir::Normalize<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Normalize {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Normalize<ChalkIr> {
        chalk_ir::Normalize {
            projection: self.projection_ty.to_chalk(db),
            ty: self.ty.to_chalk(db),
        }
    }
-    fn from_chalk(_db: &impl HirDatabase, _normalize: chalk_ir::Normalize) -> Self {
+    fn from_chalk(_db: &impl HirDatabase, _normalize: chalk_ir::Normalize<ChalkIr>) -> Self {
        unimplemented!()
    }
 }
 impl ToChalk for Obligation {
-    type Chalk = chalk_ir::DomainGoal;
+    type Chalk = chalk_ir::DomainGoal<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::DomainGoal {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::DomainGoal<ChalkIr> {
        match self {
            Obligation::Trait(tr) => tr.to_chalk(db).cast(),
            Obligation::Projection(pr) => pr.to_chalk(db).cast(),
        }
    }
-    fn from_chalk(_db: &impl HirDatabase, _goal: chalk_ir::DomainGoal) -> Self {
+    fn from_chalk(_db: &impl HirDatabase, _goal: chalk_ir::DomainGoal<ChalkIr>) -> Self {
        unimplemented!()
    }
 }
@@ -296,16 +324,16 @@ where
 }
 impl ToChalk for Arc<super::TraitEnvironment> {
-    type Chalk = Arc<chalk_ir::Environment>;
+    type Chalk = chalk_ir::Environment<ChalkIr>;
-    fn to_chalk(self, db: &impl HirDatabase) -> Arc<chalk_ir::Environment> {
+    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::Environment<ChalkIr> {
        let mut clauses = Vec::new();
        for pred in &self.predicates {
            if pred.is_error() {
                // for env, we just ignore errors
                continue;
            }
-            let program_clause: chalk_ir::ProgramClause = pred.clone().to_chalk(db).cast();
+            let program_clause: chalk_ir::ProgramClause<ChalkIr> = pred.clone().to_chalk(db).cast();
            clauses.push(program_clause.into_from_env_clause());
        }
        chalk_ir::Environment::new().add_clauses(clauses)
@@ -313,13 +341,16 @@ impl ToChalk for Arc<super::TraitEnvironment> {
    fn from_chalk(
        _db: &impl HirDatabase,
-        _env: Arc<chalk_ir::Environment>,
+        _env: chalk_ir::Environment<ChalkIr>,
    ) -> Arc<super::TraitEnvironment> {
        unimplemented!()
    }
 }
-impl<T: ToChalk> ToChalk for super::InEnvironment<T> {
+impl<T: ToChalk> ToChalk for super::InEnvironment<T>
+where
+    T::Chalk: chalk_ir::family::HasTypeFamily<TypeFamily = ChalkIr>,
+{
    type Chalk = chalk_ir::InEnvironment<T::Chalk>;
    fn to_chalk(self, db: &impl HirDatabase) -> chalk_ir::InEnvironment<T::Chalk> {
@@ -351,7 +382,7 @@ fn convert_where_clauses(
    db: &impl HirDatabase,
    def: GenericDef,
    substs: &Substs,
-) -> Vec<chalk_ir::QuantifiedWhereClause> {
+) -> Vec<chalk_ir::QuantifiedWhereClause<ChalkIr>> {
    let generic_predicates = db.generic_predicates(def);
    let mut result = Vec::with_capacity(generic_predicates.len());
    for pred in generic_predicates.iter() {
@@ -384,7 +415,7 @@ where
    fn impls_for_trait(
        &self,
        trait_id: chalk_ir::TraitId,
-        parameters: &[Parameter],
+        parameters: &[Parameter<ChalkIr>],
    ) -> Vec<ImplId> {
        debug!("impls_for_trait {:?}", trait_id);
        if trait_id == UNKNOWN_TRAIT {
@@ -430,13 +461,13 @@ where
    }
    fn split_projection<'p>(
        &self,
-        projection: &'p chalk_ir::ProjectionTy,
+        projection: &'p chalk_ir::ProjectionTy<ChalkIr>,
-    ) -> (Arc<AssociatedTyDatum>, &'p [Parameter], &'p [Parameter]) {
+    ) -> (Arc<AssociatedTyDatum>, &'p [Parameter<ChalkIr>], &'p [Parameter<ChalkIr>]) {
        debug!("split_projection {:?}", projection);
        // we don't support GATs, so I think this should always be correct currently
        (self.db.associated_ty_data(projection.associated_ty_id), &projection.parameters, &[])
    }
-    fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause> {
+    fn custom_clauses(&self) -> Vec<chalk_ir::ProgramClause<ChalkIr>> {
        vec![]
    }
    fn local_impls_to_coherence_check(
@@ -508,7 +539,7 @@ pub(crate) fn trait_datum_query(
    let trait_ref = trait_.trait_ref(db).subst(&bound_vars).to_chalk(db);
    let flags = chalk_rust_ir::TraitFlags {
        auto: trait_.is_auto(db),
-        upstream: trait_.module(db).krate(db) != Some(krate),
+        upstream: trait_.module(db).krate() != krate,
        non_enumerable: true,
        // FIXME set these flags correctly
        marker: false,
@@ -596,7 +627,7 @@ fn impl_block_datum(
        .target_trait_ref(db)
        .expect("FIXME handle unresolved impl block trait ref")
        .subst(&bound_vars);
-    let impl_type = if impl_block.module().krate(db) == Some(krate) {
+    let impl_type = if impl_block.module().krate() == krate {
        chalk_rust_ir::ImplType::Local
    } else {
        chalk_rust_ir::ImplType::External
@@ -705,7 +736,7 @@ fn closure_fn_trait_impl_datum(
        substs: Substs::build_for_def(db, trait_).push(self_ty).push(arg_ty).build(),
    };
-    let output_ty_id = fn_once_trait.associated_type_by_name(db, &crate::name::OUTPUT_TYPE)?;
+    let output_ty_id = fn_once_trait.associated_type_by_name(db, &name::OUTPUT_TYPE)?;
    let output_ty_value = chalk_rust_ir::AssociatedTyValue {
        associated_ty_id: output_ty_id.to_chalk(db),
@@ -746,30 +777,6 @@ fn id_to_chalk<T: InternKey>(salsa_id: T) -> chalk_ir::RawId {
    chalk_ir::RawId { index: salsa_id.as_intern_id().as_u32() }
 }
-impl From<chalk_ir::TraitId> for crate::ids::TraitId {
-    fn from(trait_id: chalk_ir::TraitId) -> Self {
-        id_from_chalk(trait_id.0)
-    }
-}
-impl From<crate::ids::TraitId> for chalk_ir::TraitId {
-    fn from(trait_id: crate::ids::TraitId) -> Self {
-        chalk_ir::TraitId(id_to_chalk(trait_id))
-    }
-}
-impl From<chalk_ir::TypeId> for crate::ids::TypeAliasId {
-    fn from(type_id: chalk_ir::TypeId) -> Self {
-        id_from_chalk(type_id.0)
-    }
-}
-impl From<crate::ids::TypeAliasId> for chalk_ir::TypeId {
-    fn from(type_id: crate::ids::TypeAliasId) -> Self {
-        chalk_ir::TypeId(id_to_chalk(type_id))
-    }
-}
 impl From<chalk_ir::StructId> for crate::ids::TypeCtorId {
    fn from(struct_id: chalk_ir::StructId) -> Self {
        id_from_chalk(struct_id.0)
diff --git a/crates/ra_hir/src/type_alias.rs b/crates/ra_hir/src/type_alias.rs
index 674a46102..078e6295e 100644
--- a/crates/ra_hir/src/type_alias.rs
+++ b/crates/ra_hir/src/type_alias.rs
@@ -2,12 +2,13 @@
 use std::sync::Arc;
+use hir_def::type_ref::TypeRef;
+use hir_expand::name::{AsName, Name};
 use ra_syntax::ast::NameOwner;
 use crate::{
    db::{AstDatabase, DefDatabase},
-    name::{AsName, Name},
-    type_ref::TypeRef,
    HasSource, TypeAlias,
 };
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
new file mode 100644
index 000000000..746c907e8
--- /dev/null
+++ b/crates/ra_hir_def/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+edition = "2018"
+name = "ra_hir_def"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+[dependencies]
+log = "0.4.5"
+once_cell = "1.0.1"
+relative-path = "1.0.0"
+rustc-hash = "1.0"
+ra_arena = { path = "../ra_arena" }
+ra_db = { path = "../ra_db" }
+ra_syntax = { path = "../ra_syntax" }
+ra_prof = { path = "../ra_prof" }
+hir_expand = { path = "../ra_hir_expand", package = "ra_hir_expand" }
+test_utils = { path = "../test_utils" }
+mbe = { path = "../ra_mbe", package = "ra_mbe" }
+ra_cfg = { path = "../ra_cfg" }
+tt = { path = "../ra_tt", package = "ra_tt" }
diff --git a/crates/ra_hir/src/attr.rs b/crates/ra_hir_def/src/attr.rs
index bd159a566..0e961ca12 100644
--- a/crates/ra_hir/src/attr.rs
+++ b/crates/ra_hir_def/src/attr.rs
@@ -2,6 +2,7 @@
 use std::sync::Arc;
+use hir_expand::hygiene::Hygiene;
 use mbe::ast_to_token_tree;
 use ra_cfg::CfgOptions;
 use ra_syntax::{
@@ -10,10 +11,10 @@ use ra_syntax::{
 };
 use tt::Subtree;
-use crate::{db::AstDatabase, path::Path, HirFileId, Source};
+use crate::path::Path;
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) struct Attr {
+pub struct Attr {
    pub(crate) path: Path,
    pub(crate) input: Option<AttrInput>,
 }
@@ -25,11 +26,8 @@ pub enum AttrInput {
 }
 impl Attr {
-    pub(crate) fn from_src(
+    pub(crate) fn from_src(ast: ast::Attr, hygiene: &Hygiene) -> Option<Attr> {
-        Source { file_id, ast }: Source<ast::Attr>,
+        let path = Path::from_src(ast.path()?, hygiene)?;
-        db: &impl AstDatabase,
-    ) -> Option<Attr> {
-        let path = Path::from_src(Source { file_id, ast: ast.path()? }, db)?;
        let input = match ast.input() {
            None => None,
            Some(ast::AttrInput::Literal(lit)) => {
@@ -45,26 +43,22 @@ impl Attr {
        Some(Attr { path, input })
    }
-    pub(crate) fn from_attrs_owner(
+    pub fn from_attrs_owner(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Option<Arc<[Attr]>> {
-        file_id: HirFileId,
-        owner: &dyn AttrsOwner,
-        db: &impl AstDatabase,
-    ) -> Option<Arc<[Attr]>> {
        let mut attrs = owner.attrs().peekable();
        if attrs.peek().is_none() {
            // Avoid heap allocation
            return None;
        }
-        Some(attrs.flat_map(|ast| Attr::from_src(Source { file_id, ast }, db)).collect())
+        Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).collect())
    }
-    pub(crate) fn is_simple_atom(&self, name: &str) -> bool {
+    pub fn is_simple_atom(&self, name: &str) -> bool {
        // FIXME: Avoid cloning
        self.path.as_ident().map_or(false, |s| s.to_string() == name)
    }
    // FIXME: handle cfg_attr :-)
-    pub(crate) fn as_cfg(&self) -> Option<&Subtree> {
+    pub fn as_cfg(&self) -> Option<&Subtree> {
        if !self.is_simple_atom("cfg") {
            return None;
        }
@@ -74,7 +68,7 @@ impl Attr {
        }
    }
-    pub(crate) fn as_path(&self) -> Option<&SmolStr> {
+    pub fn as_path(&self) -> Option<&SmolStr> {
        if !self.is_simple_atom("path") {
            return None;
        }
@@ -84,7 +78,7 @@ impl Attr {
        }
    }
-    pub(crate) fn is_cfg_enabled(&self, cfg_options: &CfgOptions) -> Option<bool> {
+    pub fn is_cfg_enabled(&self, cfg_options: &CfgOptions) -> Option<bool> {
        cfg_options.is_cfg_enabled(self.as_cfg()?)
    }
 }
diff --git a/crates/ra_hir_def/src/builtin_type.rs b/crates/ra_hir_def/src/builtin_type.rs
new file mode 100644
index 000000000..12929caa9
--- /dev/null
+++ b/crates/ra_hir_def/src/builtin_type.rs
@@ -0,0 +1,63 @@
+//! This module defines built-in types.
+//!
+//! A peculiarity of built-in types is that they are always available and are
+//! not associated with any particular crate.
+use hir_expand::name::{self, Name};
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Signedness {
+    Signed,
+    Unsigned,
+}
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum IntBitness {
+    Xsize,
+    X8,
+    X16,
+    X32,
+    X64,
+    X128,
+}
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum FloatBitness {
+    X32,
+    X64,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum BuiltinType {
+    Char,
+    Bool,
+    Str,
+    Int { signedness: Signedness, bitness: IntBitness },
+    Float { bitness: FloatBitness },
+}
+impl BuiltinType {
+    #[rustfmt::skip]
+    pub const ALL: &'static [(Name, BuiltinType)] = &[
+        (name::CHAR, BuiltinType::Char),
+        (name::BOOL, BuiltinType::Bool),
+        (name::STR,  BuiltinType::Str ),
+        (name::ISIZE, BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::Xsize }),
+        (name::I8,    BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::X8    }),
+        (name::I16,   BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::X16   }),
+        (name::I32,   BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::X32   }),
+        (name::I64,   BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::X64   }),
+        (name::I128,  BuiltinType::Int { signedness: Signedness::Signed,   bitness: IntBitness::X128  }),
+        (name::USIZE, BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::Xsize }),
+        (name::U8,    BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::X8    }),
+        (name::U16,   BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::X16   }),
+        (name::U32,   BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::X32   }),
+        (name::U64,   BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::X64   }),
+        (name::U128,  BuiltinType::Int { signedness: Signedness::Unsigned, bitness: IntBitness::X128  }),
+        (name::F32, BuiltinType::Float { bitness: FloatBitness::X32 }),
+        (name::F64, BuiltinType::Float { bitness: FloatBitness::X64 }),
+    ];
+}
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
new file mode 100644
index 000000000..b271636b0
--- /dev/null
+++ b/crates/ra_hir_def/src/db.rs
@@ -0,0 +1,40 @@
+//! Defines database & queries for name resolution.
+use std::sync::Arc;
+use hir_expand::{db::AstDatabase, HirFileId};
+use ra_db::{salsa, SourceDatabase};
+use ra_syntax::ast;
+use crate::nameres::raw::{ImportSourceMap, RawItems};
+#[salsa::query_group(InternDatabaseStorage)]
+pub trait InternDatabase: SourceDatabase {
+    #[salsa::interned]
+    fn intern_function(&self, loc: crate::ItemLoc<ast::FnDef>) -> crate::FunctionId;
+    #[salsa::interned]
+    fn intern_struct(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::StructId;
+    #[salsa::interned]
+    fn intern_union(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::UnionId;
+    #[salsa::interned]
+    fn intern_enum(&self, loc: crate::ItemLoc<ast::EnumDef>) -> crate::EnumId;
+    #[salsa::interned]
+    fn intern_const(&self, loc: crate::ItemLoc<ast::ConstDef>) -> crate::ConstId;
+    #[salsa::interned]
+    fn intern_static(&self, loc: crate::ItemLoc<ast::StaticDef>) -> crate::StaticId;
+    #[salsa::interned]
+    fn intern_trait(&self, loc: crate::ItemLoc<ast::TraitDef>) -> crate::TraitId;
+    #[salsa::interned]
+    fn intern_type_alias(&self, loc: crate::ItemLoc<ast::TypeAliasDef>) -> crate::TypeAliasId;
+}
+#[salsa::query_group(DefDatabase2Storage)]
+pub trait DefDatabase2: InternDatabase + AstDatabase {
+    #[salsa::invoke(RawItems::raw_items_with_source_map_query)]
+    fn raw_items_with_source_map(
+        &self,
+        file_id: HirFileId,
+    ) -> (Arc<RawItems>, Arc<ImportSourceMap>);
+    #[salsa::invoke(RawItems::raw_items_query)]
+    fn raw_items(&self, file_id: HirFileId) -> Arc<RawItems>;
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
new file mode 100644
index 000000000..93ad40005
--- /dev/null
+++ b/crates/ra_hir_def/src/lib.rs
@@ -0,0 +1,362 @@
+//! `hir_def` crate contains everything between macro expansion and type
+//! inference.
+//!
+//! It defines various items (structs, enums, traits) which comprises Rust code,
+//! as well as an algorithm for resolving paths to such entities.
+//!
+//! Note that `hir_def` is a work in progress, so not all of the above is
+//! actually true.
+pub mod db;
+pub mod attr;
+pub mod path;
+pub mod type_ref;
+pub mod builtin_type;
+// FIXME: this should be private
+pub mod nameres;
+use std::hash::{Hash, Hasher};
+use hir_expand::{ast_id_map::FileAstId, db::AstDatabase, AstId, HirFileId};
+use ra_arena::{impl_arena_id, RawId};
+use ra_db::{salsa, CrateId, FileId};
+use ra_syntax::{ast, AstNode, SyntaxNode};
+use crate::{builtin_type::BuiltinType, db::InternDatabase};
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct Source<T> {
+    pub file_id: HirFileId,
+    pub ast: T,
+}
+pub enum ModuleSource {
+    SourceFile(ast::SourceFile),
+    Module(ast::Module),
+}
+impl ModuleSource {
+    pub fn new(
+        db: &impl db::DefDatabase2,
+        file_id: Option<FileId>,
+        decl_id: Option<AstId<ast::Module>>,
+    ) -> ModuleSource {
+        match (file_id, decl_id) {
+            (Some(file_id), _) => {
+                let source_file = db.parse(file_id).tree();
+                ModuleSource::SourceFile(source_file)
+            }
+            (None, Some(item_id)) => {
+                let module = item_id.to_node(db);
+                assert!(module.item_list().is_some(), "expected inline module");
+                ModuleSource::Module(module)
+            }
+            (None, None) => panic!(),
+        }
+    }
+    // FIXME: this methods do not belong here
+    pub fn from_position(
+        db: &impl db::DefDatabase2,
+        position: ra_db::FilePosition,
+    ) -> ModuleSource {
+        let parse = db.parse(position.file_id);
+        match &ra_syntax::algo::find_node_at_offset::<ast::Module>(
+            parse.tree().syntax(),
+            position.offset,
+        ) {
+            Some(m) if !m.has_semi() => ModuleSource::Module(m.clone()),
+            _ => {
+                let source_file = parse.tree();
+                ModuleSource::SourceFile(source_file)
+            }
+        }
+    }
+    pub fn from_child_node(
+        db: &impl db::DefDatabase2,
+        file_id: FileId,
+        child: &SyntaxNode,
+    ) -> ModuleSource {
+        if let Some(m) = child.ancestors().filter_map(ast::Module::cast).find(|it| !it.has_semi()) {
+            ModuleSource::Module(m)
+        } else {
+            let source_file = db.parse(file_id).tree();
+            ModuleSource::SourceFile(source_file)
+        }
+    }
+    pub fn from_file_id(db: &impl db::DefDatabase2, file_id: FileId) -> ModuleSource {
+        let source_file = db.parse(file_id).tree();
+        ModuleSource::SourceFile(source_file)
+    }
+}
+impl<T> Source<T> {
+    pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
+        Source { file_id: self.file_id, ast: f(self.ast) }
+    }
+    pub fn file_syntax(&self, db: &impl AstDatabase) -> SyntaxNode {
+        db.parse_or_expand(self.file_id).expect("source created from invalid file")
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ModuleId {
+    pub krate: CrateId,
+    pub module_id: CrateModuleId,
+}
+/// An ID of a module, **local** to a specific crate
+// FIXME: rename to `LocalModuleId`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct CrateModuleId(RawId);
+impl_arena_id!(CrateModuleId);
+macro_rules! impl_intern_key {
+    ($name:ident) => {
+        impl salsa::InternKey for $name {
+            fn from_intern_id(v: salsa::InternId) -> Self {
+                $name(v)
+            }
+            fn as_intern_id(&self) -> salsa::InternId {
+                self.0
+            }
+        }
+    };
+}
+#[derive(Debug)]
+pub struct ItemLoc<N: AstNode> {
+    pub(crate) module: ModuleId,
+    ast_id: AstId<N>,
+}
+impl<N: AstNode> PartialEq for ItemLoc<N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.module == other.module && self.ast_id == other.ast_id
+    }
+}
+impl<N: AstNode> Eq for ItemLoc<N> {}
+impl<N: AstNode> Hash for ItemLoc<N> {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.module.hash(hasher);
+        self.ast_id.hash(hasher);
+    }
+}
+impl<N: AstNode> Clone for ItemLoc<N> {
+    fn clone(&self) -> ItemLoc<N> {
+        ItemLoc { module: self.module, ast_id: self.ast_id }
+    }
+}
+#[derive(Clone, Copy)]
+pub struct LocationCtx<DB> {
+    db: DB,
+    module: ModuleId,
+    file_id: HirFileId,
+}
+impl<'a, DB> LocationCtx<&'a DB> {
+    pub fn new(db: &'a DB, module: ModuleId, file_id: HirFileId) -> LocationCtx<&'a DB> {
+        LocationCtx { db, module, file_id }
+    }
+}
+impl<'a, DB: AstDatabase + InternDatabase> LocationCtx<&'a DB> {
+    pub fn to_def<N, DEF>(self, ast: &N) -> DEF
+    where
+        N: AstNode,
+        DEF: AstItemDef<N>,
+    {
+        DEF::from_ast(self, ast)
+    }
+}
+pub trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<N>) -> Self;
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<N>;
+    fn from_ast(ctx: LocationCtx<&(impl AstDatabase + InternDatabase)>, ast: &N) -> Self {
+        let items = ctx.db.ast_id_map(ctx.file_id);
+        let item_id = items.ast_id(ast);
+        Self::from_ast_id(ctx, item_id)
+    }
+    fn from_ast_id(ctx: LocationCtx<&impl InternDatabase>, ast_id: FileAstId<N>) -> Self {
+        let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
+        Self::intern(ctx.db, loc)
+    }
+    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
+        let loc = self.lookup_intern(db);
+        let ast = loc.ast_id.to_node(db);
+        Source { file_id: loc.ast_id.file_id(), ast }
+    }
+    fn module(self, db: &impl InternDatabase) -> ModuleId {
+        let loc = self.lookup_intern(db);
+        loc.module
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct FunctionId(salsa::InternId);
+impl_intern_key!(FunctionId);
+impl AstItemDef<ast::FnDef> for FunctionId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::FnDef>) -> Self {
+        db.intern_function(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::FnDef> {
+        db.lookup_intern_function(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StructId(salsa::InternId);
+impl_intern_key!(StructId);
+impl AstItemDef<ast::StructDef> for StructId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
+        db.intern_struct(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
+        db.lookup_intern_struct(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct UnionId(salsa::InternId);
+impl_intern_key!(UnionId);
+impl AstItemDef<ast::StructDef> for UnionId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
+        db.intern_union(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
+        db.lookup_intern_union(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumId(salsa::InternId);
+impl_intern_key!(EnumId);
+impl AstItemDef<ast::EnumDef> for EnumId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::EnumDef>) -> Self {
+        db.intern_enum(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::EnumDef> {
+        db.lookup_intern_enum(self)
+    }
+}
+// FIXME: rename to `VariantId`, only enums can ave variants
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumVariantId {
+    parent: EnumId,
+    local_id: LocalEnumVariantId,
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LocalEnumVariantId(RawId);
+impl_arena_id!(LocalEnumVariantId);
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct ConstId(salsa::InternId);
+impl_intern_key!(ConstId);
+impl AstItemDef<ast::ConstDef> for ConstId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::ConstDef>) -> Self {
+        db.intern_const(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::ConstDef> {
+        db.lookup_intern_const(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StaticId(salsa::InternId);
+impl_intern_key!(StaticId);
+impl AstItemDef<ast::StaticDef> for StaticId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StaticDef>) -> Self {
+        db.intern_static(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StaticDef> {
+        db.lookup_intern_static(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TraitId(salsa::InternId);
+impl_intern_key!(TraitId);
+impl AstItemDef<ast::TraitDef> for TraitId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TraitDef>) -> Self {
+        db.intern_trait(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TraitDef> {
+        db.lookup_intern_trait(self)
+    }
+}
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeAliasId(salsa::InternId);
+impl_intern_key!(TypeAliasId);
+impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
+    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::TypeAliasDef>) -> Self {
+        db.intern_type_alias(loc)
+    }
+    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::TypeAliasDef> {
+        db.lookup_intern_type_alias(self)
+    }
+}
+macro_rules! impl_froms {
+    ($e:ident: $($v:ident $(($($sv:ident),*))?),*) => {
+        $(
+            impl From<$v> for $e {
+                fn from(it: $v) -> $e {
+                    $e::$v(it)
+                }
+            }
+            $($(
+                impl From<$sv> for $e {
+                    fn from(it: $sv) -> $e {
+                        $e::$v($v::$sv(it))
+                    }
+                }
+            )*)?
+        )*
+    }
+}
+/// A Data Type
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum AdtId {
+    StructId(StructId),
+    UnionId(UnionId),
+    EnumId(EnumId),
+}
+impl_froms!(AdtId: StructId, UnionId, EnumId);
+/// The defs which can be visible in the module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ModuleDefId {
+    ModuleId(ModuleId),
+    FunctionId(FunctionId),
+    AdtId(AdtId),
+    // Can't be directly declared, but can be imported.
+    EnumVariantId(EnumVariantId),
+    ConstId(ConstId),
+    StaticId(StaticId),
+    TraitId(TraitId),
+    TypeAliasId(TypeAliasId),
+    BuiltinType(BuiltinType),
+}
+impl_froms!(
+    ModuleDefId: ModuleId,
+    FunctionId,
+    AdtId(StructId, EnumId, UnionId),
+    EnumVariantId,
+    ConstId,
+    StaticId,
+    TraitId,
+    TypeAliasId,
+    BuiltinType
+);
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
new file mode 100644
index 000000000..11ba8a777
--- /dev/null
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -0,0 +1,5 @@
+//! FIXME: write short doc here
+// FIXME: review privacy of submodules
+pub mod raw;
+pub mod mod_resolution;
diff --git a/crates/ra_hir/src/nameres/mod_resolution.rs b/crates/ra_hir_def/src/nameres/mod_resolution.rs
index e8b808514..7d7e2779a 100644
--- a/crates/ra_hir/src/nameres/mod_resolution.rs
+++ b/crates/ra_hir_def/src/nameres/mod_resolution.rs
@@ -1,12 +1,13 @@
 //! This module resolves `mod foo;` declaration to file.
+use hir_expand::name::Name;
 use ra_db::FileId;
 use ra_syntax::SmolStr;
 use relative_path::RelativePathBuf;
-use crate::{db::DefDatabase, HirFileId, Name};
+use crate::{db::DefDatabase2, HirFileId};
 #[derive(Clone, Debug)]
-pub(super) struct ModDir {
+pub struct ModDir {
    /// `.` for `mod.rs`, `lib.rs`
    /// `./foo` for `foo.rs`
    /// `./foo/bar` for `mod bar { mod x; }` nested in `foo.rs`
@@ -16,24 +17,17 @@ pub(super) struct ModDir {
 }
 impl ModDir {
-    pub(super) fn root() -> ModDir {
+    pub fn root() -> ModDir {
        ModDir { path: RelativePathBuf::default(), root_non_dir_owner: false }
    }
-    pub(super) fn descend_into_definition(
+    pub fn descend_into_definition(&self, name: &Name, attr_path: Option<&SmolStr>) -> ModDir {
-        &self,
-        name: &Name,
-        attr_path: Option<&SmolStr>,
-    ) -> ModDir {
        let mut path = self.path.clone();
        match attr_to_path(attr_path) {
            None => path.push(&name.to_string()),
            Some(attr_path) => {
                if self.root_non_dir_owner {
-                    // Workaround for relative path API: turn `lib.rs` into ``.
+                    assert!(path.pop());
-                    if !path.pop() {
-                        path = RelativePathBuf::default();
-                    }
                }
                path.push(attr_path);
            }
@@ -41,24 +35,20 @@ impl ModDir {
        ModDir { path, root_non_dir_owner: false }
    }
-    pub(super) fn resolve_declaration(
+    pub fn resolve_declaration(
        &self,
-        db: &impl DefDatabase,
+        db: &impl DefDatabase2,
        file_id: HirFileId,
        name: &Name,
        attr_path: Option<&SmolStr>,
    ) -> Result<(FileId, ModDir), RelativePathBuf> {
-        let empty_path = RelativePathBuf::default();
        let file_id = file_id.original_file(db);
        let mut candidate_files = Vec::new();
        match attr_to_path(attr_path) {
            Some(attr_path) => {
-                let base = if self.root_non_dir_owner {
+                let base =
-                    self.path.parent().unwrap_or(&empty_path)
+                    if self.root_non_dir_owner { self.path.parent().unwrap() } else { &self.path };
-                } else {
-                    &self.path
-                };
                candidate_files.push(base.join(attr_path))
            }
            None => {
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir_def/src/nameres/raw.rs
index 57f2929c3..86c05d602 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir_def/src/nameres/raw.rs
@@ -2,18 +2,20 @@
 use std::{ops::Index, sync::Arc};
+use hir_expand::{
+    ast_id_map::AstIdMap,
+    db::AstDatabase,
+    either::Either,
+    hygiene::Hygiene,
+    name::{AsName, Name},
+};
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
 use ra_syntax::{
    ast::{self, AttrsOwner, NameOwner},
    AstNode, AstPtr, SourceFile,
 };
-use test_utils::tested_by;
-use crate::{
+use crate::{attr::Attr, db::DefDatabase2, path::Path, FileAstId, HirFileId, ModuleSource, Source};
-    attr::Attr,
-    db::{AstDatabase, DefDatabase},
-    AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path, Source,
-};
 /// `RawItems` is a set of top-level items in a file (except for impls).
 ///
@@ -37,10 +39,8 @@ pub struct ImportSourceMap {
 type ImportSourcePtr = Either<AstPtr<ast::UseTree>, AstPtr<ast::ExternCrateItem>>;