51 files changed, 1538 insertions, 1172 deletions

diff --git a/.gitattributes b/.gitattributes
index a77342d72..183e9b521 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1 +1,2 @@
-crates/ra_syntax/tests/data/** -text
+crates/ra_syntax/test_data/** -text eof=LF
+crates/ra_ide_api/src/snapshots/** -text eof=LF
diff --git a/Cargo.lock b/Cargo.lock
index 29f77044e..3879204d9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -985,6 +985,7 @@ dependencies = [
  "relative-path 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "salsa 0.13.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "test_utils 0.1.0",
 ]
 
 [[package]]
@@ -1018,7 +1019,6 @@ dependencies = [
  "ra_prof 0.1.0",
  "ra_syntax 0.1.0",
  "ra_tt 0.1.0",
- "relative-path 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
@@ -1027,6 +1027,7 @@ dependencies = [
 name = "ra_hir_def"
 version = "0.1.0"
 dependencies = [
+ "insta 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "once_cell 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_arena 0.1.0",
@@ -1037,7 +1038,6 @@ dependencies = [
  "ra_prof 0.1.0",
  "ra_syntax 0.1.0",
  "ra_tt 0.1.0",
- "relative-path 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
@@ -1077,7 +1077,6 @@ dependencies = [
  "ra_text_edit 0.1.0",
  "rand 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "relative-path 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "superslice 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
diff --git a/crates/ra_assists/src/assists/early_return.rs b/crates/ra_assists/src/assists/early_return.rs
index ad6c5695a..570a07a20 100644
--- a/crates/ra_assists/src/assists/early_return.rs
+++ b/crates/ra_assists/src/assists/early_return.rs
@@ -3,9 +3,10 @@ use std::ops::RangeInclusive;
 use hir::db::HirDatabase;
 use ra_syntax::{
     algo::replace_children,
-    ast::{self, edit::IndentLevel, make},
+    ast::{self, edit::IndentLevel, make, Block, Pat::TupleStructPat},
     AstNode,
     SyntaxKind::{FN_DEF, LOOP_EXPR, L_CURLY, R_CURLY, WHILE_EXPR, WHITESPACE},
+    SyntaxNode,
 };
 
 use crate::{
@@ -37,7 +38,23 @@ use crate::{
 // ```
 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 cond = if_expr.condition()?;
+    let mut if_let_ident: Option<String> = None;
+
+    // Check if there is an IfLet that we can handle.
+    match cond.pat() {
+        None => {} // No IfLet, supported.
+        Some(TupleStructPat(ref pat)) if pat.args().count() == 1usize => match &pat.path() {
+            Some(p) => match p.qualifier() {
+                None => if_let_ident = Some(p.syntax().text().to_string()),
+                _ => return None,
+            },
+            _ => return None,
+        },
+        _ => return None, // Unsupported IfLet.
+    };
+
+    let expr = cond.expr()?;
     let then_block = if_expr.then_branch()?.block()?;
     if if_expr.else_branch().is_some() {
         return None;
@@ -63,8 +80,8 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
     let parent_container = parent_block.syntax().parent()?.parent()?;
 
     let early_expression = match parent_container.kind() {
-        WHILE_EXPR | LOOP_EXPR => Some("continue;"),
-        FN_DEF => Some("return;"),
+        WHILE_EXPR | LOOP_EXPR => Some("continue"),
+        FN_DEF => Some("return"),
         _ => None,
     }?;
 
@@ -77,34 +94,58 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
 
     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));
-        let then_block_items = IndentLevel::from(1).decrease_indent(then_block.clone());
-        let end_of_then = then_block_items.syntax().last_child_or_token().unwrap();
-        let end_of_then =
-            if end_of_then.prev_sibling_or_token().map(|n| n.kind()) == Some(WHITESPACE) {
-                end_of_then.prev_sibling_or_token().unwrap()
-            } else {
-                end_of_then
-            };
-        let mut new_if_and_then_statements = new_if_expr.syntax().children_with_tokens().chain(
-            then_block_items
-                .syntax()
-                .children_with_tokens()
-                .skip(1)
-                .take_while(|i| *i != end_of_then),
-        );
-        let new_block = replace_children(
-            &parent_block.syntax(),
-            RangeInclusive::new(
-                if_expr.clone().syntax().clone().into(),
-                if_expr.syntax().clone().into(),
-            ),
-            &mut new_if_and_then_statements,
-        );
+        let new_block = match if_let_ident {
+            None => {
+                // If.
+                let early_expression = &(early_expression.to_owned() + ";");
+                let new_expr =
+                    if_indent_level.increase_indent(make::if_expression(&expr, early_expression));
+                replace(new_expr, &then_block, &parent_block, &if_expr)
+            }
+            Some(if_let_ident) => {
+                // If-let.
+                let new_expr = if_indent_level.increase_indent(make::let_match_early(
+                    expr,
+                    &if_let_ident,
+                    early_expression,
+                ));
+                replace(new_expr, &then_block, &parent_block, &if_expr)
+            }
+        };
         edit.target(if_expr.syntax().text_range());
         edit.replace_ast(parent_block, ast::Block::cast(new_block).unwrap());
         edit.set_cursor(cursor_position);
+
+        fn replace(
+            new_expr: impl AstNode,
+            then_block: &Block,
+            parent_block: &Block,
+            if_expr: &ast::IfExpr,
+        ) -> SyntaxNode {
+            let then_block_items = IndentLevel::from(1).decrease_indent(then_block.clone());
+            let end_of_then = then_block_items.syntax().last_child_or_token().unwrap();
+            let end_of_then =
+                if end_of_then.prev_sibling_or_token().map(|n| n.kind()) == Some(WHITESPACE) {
+                    end_of_then.prev_sibling_or_token().unwrap()
+                } else {
+                    end_of_then
+                };
+            let mut then_statements = new_expr.syntax().children_with_tokens().chain(
+                then_block_items
+                    .syntax()
+                    .children_with_tokens()
+                    .skip(1)
+                    .take_while(|i| *i != end_of_then),
+            );
+            replace_children(
+                &parent_block.syntax(),
+                RangeInclusive::new(
+                    if_expr.clone().syntax().clone().into(),
+                    if_expr.syntax().clone().into(),
+                ),
+                &mut then_statements,
+            )
+        }
     })
 }
 
@@ -144,6 +185,68 @@ mod tests {
     }
 
     #[test]
+    fn convert_let_inside_fn() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+            fn main(n: Option<String>) {
+                bar();
+                if<|> let Some(n) = n {
+                    foo(n);
+
+                    //comment
+                    bar();
+                }
+            }
+            "#,
+            r#"
+            fn main(n: Option<String>) {
+                bar();
+                le<|>t n = match n {
+                    Some(it) => it,
+                    None => return,
+                };
+                foo(n);
+
+                //comment
+                bar();
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn convert_let_ok_inside_fn() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+            fn main(n: Option<String>) {
+                bar();
+                if<|> let Ok(n) = n {
+                    foo(n);
+
+                    //comment
+                    bar();
+                }
+            }
+            "#,
+            r#"
+            fn main(n: Option<String>) {
+                bar();
+                le<|>t n = match n {
+                    Ok(it) => it,
+                    None => return,
+                };
+                foo(n);
+
+                //comment
+                bar();
+            }
+            "#,
+        );
+    }
+
+    #[test]
     fn convert_inside_while() {
         check_assist(
             convert_to_guarded_return,
@@ -172,6 +275,35 @@ mod tests {
     }
 
     #[test]
+    fn convert_let_inside_while() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+            fn main() {
+                while true {
+                    if<|> let Some(n) = n {
+                        foo(n);
+                        bar();
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                while true {
+                    le<|>t n = match n {
+                        Some(it) => it,
+                        None => continue,
+                    };
+                    foo(n);
+                    bar();
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
     fn convert_inside_loop() {
         check_assist(
             convert_to_guarded_return,
@@ -200,6 +332,35 @@ mod tests {
     }
 
     #[test]
+    fn convert_let_inside_loop() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+            fn main() {
+                loop {
+                    if<|> let Some(n) = n {
+                        foo(n);
+                        bar();
+                    }
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                loop {
+                    le<|>t n = match n {
+                        Some(it) => it,
+                        None => continue,
+                    };
+                    foo(n);
+                    bar();
+                }
+            }
+            "#,
+        );
+    }
+
+    #[test]
     fn ignore_already_converted_if() {
         check_assist_not_applicable(
             convert_to_guarded_return,
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 3394ae8ce..bf1f7920c 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -12,3 +12,4 @@ rustc-hash = "1.0"
 ra_syntax = { path = "../ra_syntax" }
 ra_cfg = { path = "../ra_cfg" }
 ra_prof = { path = "../ra_prof" }
+test_utils = { path = "../test_utils" }
diff --git a/crates/ra_db/src/fixture.rs b/crates/ra_db/src/fixture.rs
new file mode 100644
index 000000000..f5dd59f84
--- /dev/null
+++ b/crates/ra_db/src/fixture.rs
@@ -0,0 +1,186 @@
+//! FIXME: write short doc here
+
+use std::sync::Arc;
+
+use ra_cfg::CfgOptions;
+use rustc_hash::FxHashMap;
+use test_utils::{extract_offset, parse_fixture, CURSOR_MARKER};
+
+use crate::{
+    CrateGraph, Edition, FileId, FilePosition, RelativePathBuf, SourceDatabaseExt, SourceRoot,
+    SourceRootId,
+};
+
+pub const WORKSPACE: SourceRootId = SourceRootId(0);
+
+pub trait WithFixture: Default + SourceDatabaseExt + 'static {
+    fn with_single_file(text: &str) -> (Self, FileId) {
+        let mut db = Self::default();
+        let file_id = with_single_file(&mut db, text);
+        (db, file_id)
+    }
+
+    fn with_files(fixture: &str) -> Self {
+        let mut db = Self::default();
+        let pos = with_files(&mut db, fixture);
+        assert!(pos.is_none());
+        db
+    }
+
+    fn with_position(fixture: &str) -> (Self, FilePosition) {
+        let mut db = Self::default();
+        let pos = with_files(&mut db, fixture);
+        (db, pos.unwrap())
+    }
+}
+
+impl<DB: SourceDatabaseExt + Default + 'static> WithFixture for DB {}
+
+fn with_single_file(db: &mut dyn SourceDatabaseExt, text: &str) -> FileId {
+    let file_id = FileId(0);
+    let rel_path: RelativePathBuf = "/main.rs".into();
+
+    let mut source_root = SourceRoot::default();
+    source_root.insert_file(rel_path.clone(), file_id);
+
+    let mut crate_graph = CrateGraph::default();
+    crate_graph.add_crate_root(file_id, Edition::Edition2018, CfgOptions::default());
+
+    db.set_file_text(file_id, Arc::new(text.to_string()));
+    db.set_file_relative_path(file_id, rel_path);
+    db.set_file_source_root(file_id, WORKSPACE);
+    db.set_source_root(WORKSPACE, Arc::new(source_root));
+    db.set_crate_graph(Arc::new(crate_graph));
+
+    file_id
+}
+
+fn with_files(db: &mut dyn SourceDatabaseExt, fixture: &str) -> Option<FilePosition> {
+    let fixture = parse_fixture(fixture);
+
+    let mut crate_graph = CrateGraph::default();
+    let mut crates = FxHashMap::default();
+    let mut crate_deps = Vec::new();
+    let mut default_crate_root: Option<FileId> = None;
+
+    let mut source_root = SourceRoot::default();
+    let mut source_root_id = WORKSPACE;
+    let mut source_root_prefix: RelativePathBuf = "/".into();
+    let mut file_id = FileId(0);
+
+    let mut file_position = None;
+
+    for entry in fixture.iter() {
+        let meta = match parse_meta(&entry.meta) {
+            ParsedMeta::Root { path } => {
+                let source_root = std::mem::replace(&mut source_root, SourceRoot::default());
+                db.set_source_root(source_root_id, Arc::new(source_root));
+                source_root_id.0 += 1;
+                source_root_prefix = path;
+                continue;
+            }
+            ParsedMeta::File(it) => it,
+        };
+        assert!(meta.path.starts_with(&source_root_prefix));
+
+        if let Some(krate) = meta.krate {
+            let crate_id = crate_graph.add_crate_root(file_id, meta.edition, meta.cfg);
+            let prev = crates.insert(krate.clone(), crate_id);
+            assert!(prev.is_none());
+            for dep in meta.deps {
+                crate_deps.push((krate.clone(), dep))
+            }
+        } else if meta.path == "/main.rs" || meta.path == "/lib.rs" {
+            assert!(default_crate_root.is_none());
+            default_crate_root = Some(file_id);
+        }
+
+        let text = if entry.text.contains(CURSOR_MARKER) {
+            let (offset, text) = extract_offset(&entry.text);
+            assert!(file_position.is_none());
+            file_position = Some(FilePosition { file_id, offset });
+            text.to_string()
+        } else {
+            entry.text.to_string()
+        };
+
+        db.set_file_text(file_id, Arc::new(text));
+        db.set_file_relative_path(file_id, meta.path.clone());
+        db.set_file_source_root(file_id, source_root_id);
+        source_root.insert_file(meta.path, file_id);
+
+        file_id.0 += 1;
+    }
+
+    if crates.is_empty() {
+        let crate_root = default_crate_root.unwrap();
+        crate_graph.add_crate_root(crate_root, Edition::Edition2018, CfgOptions::default());
+    } else {
+        for (from, to) in crate_deps {
+            let from_id = crates[&from];
+            let to_id = crates[&to];
+            crate_graph.add_dep(from_id, to.into(), to_id).unwrap();
+        }
+    }
+
+    db.set_source_root(source_root_id, Arc::new(source_root));
+    db.set_crate_graph(Arc::new(crate_graph));
+
+    file_position
+}
+
+enum ParsedMeta {
+    Root { path: RelativePathBuf },
+    File(FileMeta),
+}
+
+struct FileMeta {
+    path: RelativePathBuf,
+    krate: Option<String>,
+    deps: Vec<String>,
+    cfg: CfgOptions,
+    edition: Edition,
+}
+
+//- /lib.rs crate:foo deps:bar,baz
+fn parse_meta(meta: &str) -> ParsedMeta {
+    let components = meta.split_ascii_whitespace().collect::<Vec<_>>();
+
+    if components[0] == "root" {
+        let path: RelativePathBuf = components[1].into();
+        assert!(path.starts_with("/") && path.ends_with("/"));
+        return ParsedMeta::Root { path };
+    }
+
+    let path: RelativePathBuf = components[0].into();
+    assert!(path.starts_with("/"));
+
+    let mut krate = None;
+    let mut deps = Vec::new();
+    let mut edition = Edition::Edition2018;
+    let mut cfg = CfgOptions::default();
+    for component in components[1..].iter() {
+        let (key, value) = split1(component, ':').unwrap();
+        match key {
+            "crate" => krate = Some(value.to_string()),
+            "deps" => deps = value.split(',').map(|it| it.to_string()).collect(),
+            "edition" => edition = Edition::from_string(&value),
+            "cfg" => {
+                for key in value.split(',') {
+                    match split1(key, '=') {
+                        None => cfg.insert_atom(key.into()),
+                        Some((k, v)) => cfg.insert_key_value(k.into(), v.into()),
+                    }
+                }
+            }
+            _ => panic!("bad component: {:?}", component),
+        }
+    }
+
+    ParsedMeta::File(FileMeta { path, krate, deps, edition, cfg })
+}
+
+fn split1(haystack: &str, delim: char) -> Option<(&str, &str)> {
+    let idx = haystack.find(delim)?;
+    Some((&haystack[..idx], &haystack[idx + delim.len_utf8()..]))
+}
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index eafa95921..60f7dc881 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -6,13 +6,14 @@
 //! actual IO. See `vfs` and `project_model` in the `ra_lsp_server` crate for how
 //! actual IO is done and lowered to input.
 
-use relative_path::{RelativePath, RelativePathBuf};
 use rustc_hash::FxHashMap;
 
 use ra_cfg::CfgOptions;
 use ra_syntax::SmolStr;
 use rustc_hash::FxHashSet;
 
+use crate::{RelativePath, RelativePathBuf};
+
 /// `FileId` is an integer which uniquely identifies a file. File paths are
 /// messy and system-dependent, so most of the code should work directly with
 /// `FileId`, without inspecting the path. The mapping between `FileId` and path
@@ -97,6 +98,7 @@ pub enum Edition {
 }
 
 impl Edition {
+    //FIXME: replace with FromStr with proper error handling
     pub fn from_string(s: &str) -> Edition {
         match s {
             "2015" => Edition::Edition2015,
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index 0d1ab4843..b6bfd531d 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -1,17 +1,18 @@
 //! ra_db defines basic database traits. The concrete DB is defined by ra_ide_api.
 mod cancellation;
 mod input;
+pub mod fixture;
 
 use std::{panic, sync::Arc};
 
 use ra_prof::profile;
 use ra_syntax::{ast, Parse, SourceFile, TextRange, TextUnit};
-use relative_path::{RelativePath, RelativePathBuf};
 
 pub use crate::{
     cancellation::Canceled,
     input::{CrateGraph, CrateId, Dependency, Edition, FileId, SourceRoot, SourceRootId},
 };
+pub use relative_path::{RelativePath, RelativePathBuf};
 pub use salsa;
 
 pub trait CheckCanceled {
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index fae5dc7cb..324961328 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -7,7 +7,6 @@ authors = ["rust-analyzer developers"]
 [dependencies]
 arrayvec = "0.5.1"
 log = "0.4.5"
-relative-path = "1.0.0"
 rustc-hash = "1.0"
 parking_lot = "0.9.0"
 ena = "0.13"
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 5b78bdfef..181c5d47a 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -9,7 +9,7 @@ use hir_def::{
     adt::VariantData,
     builtin_type::BuiltinType,
     type_ref::{Mutability, TypeRef},
-    CrateModuleId, LocalEnumVariantId, LocalStructFieldId, ModuleId,
+    CrateModuleId, LocalEnumVariantId, LocalStructFieldId, ModuleId, UnionId,
 };
 use hir_expand::{
     diagnostics::DiagnosticSink,
@@ -28,11 +28,10 @@ use crate::{
         TypeAliasId,
     },
     impl_block::ImplBlock,
-    nameres::{ImportId, ModuleScope, Namespace},
     resolve::{Resolver, Scope, TypeNs},
     traits::TraitData,
     ty::{InferenceResult, TraitRef},
-    Either, HasSource, Name, Ty,
+    Either, HasSource, Name, ScopeDef, Ty, {ImportId, Namespace},
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -66,7 +65,7 @@ impl Crate {
     }
 
     pub fn root_module(self, db: &impl DefDatabase) -> Option<Module> {
-        let module_id = db.crate_def_map(self).root();
+        let module_id = db.crate_def_map(self.crate_id).root();
         Some(Module::new(self, module_id))
     }
 
@@ -120,7 +119,7 @@ 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.id.krate);
         let parent = def_map[self.id.module_id].parent?;
         def_map[parent].children.iter().find_map(|(name, module_id)| {
             if *module_id == self.id.module_id {
@@ -151,20 +150,20 @@ impl Module {
     /// 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.id.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.id.krate);
         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.id.krate);
         let children = def_map[self.id.module_id]
             .children
             .iter()
@@ -175,7 +174,7 @@ 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.id.krate);
         let parent_id = def_map[self.id.module_id].parent?;
         Some(self.with_module_id(parent_id))
     }
@@ -191,12 +190,16 @@ 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.id.module_id].scope.clone()
+    pub fn scope(self, db: &impl HirDatabase) -> Vec<(Name, ScopeDef, Option<ImportId>)> {
+        db.crate_def_map(self.id.krate)[self.id.module_id]
+            .scope
+            .entries()
+            .map(|(name, res)| (name.clone(), res.def.into(), res.import))
+            .collect()
     }
 
     pub fn diagnostics(self, db: &impl HirDatabase, sink: &mut DiagnosticSink) {
-        db.crate_def_map(self.krate()).add_diagnostics(db, self.id.module_id, sink);
+        db.crate_def_map(self.id.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),
@@ -220,12 +223,12 @@ 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.id.krate);
         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.id.krate);
         def_map[self.id.module_id]
             .scope
             .entries()
@@ -233,6 +236,7 @@ impl Module {
             .flat_map(|per_ns| {
                 per_ns.take_types().into_iter().chain(per_ns.take_values().into_iter())
             })
+            .map(ModuleDef::from)
             .collect()
     }
 
@@ -336,12 +340,12 @@ impl Struct {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Union {
-    pub(crate) id: StructId,
+    pub(crate) id: UnionId,
 }
 
 impl Union {
     pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
-        db.struct_data(self.id).name.clone()
+        db.union_data(self.id).name.clone()
     }
 
     pub fn module(self, db: &impl HirDatabase) -> Module {
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index bd0c3c226..6d116ee75 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -22,7 +22,7 @@ pub trait HasSource {
 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.id.krate);
         let decl_id = def_map[self.id.module_id].declaration;
         let file_id = def_map[self.id.module_id].definition;
         let ast = ModuleSource::new(db, file_id, decl_id);
@@ -36,7 +36,7 @@ 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.id.krate);
         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 89ca4e39f..eb66325f7 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -11,20 +11,19 @@ use crate::{
     ids,
     impl_block::{ImplBlock, ImplSourceMap, ModuleImplBlocks},
     lang_item::{LangItemTarget, LangItems},
-    nameres::{CrateDefMap, Namespace},
     traits::TraitData,
     ty::{
         method_resolution::CrateImplBlocks, traits::Impl, CallableDef, FnSig, GenericPredicate,
         InferenceResult, Substs, Ty, TypableDef, TypeCtor,
     },
     type_alias::TypeAliasData,
-    Const, ConstData, Crate, DefWithBody, ExprScopes, FnData, Function, Module, Static,
+    Const, ConstData, Crate, DefWithBody, ExprScopes, FnData, Function, Module, Namespace, Static,
     StructField, Trait, TypeAlias,
 };
 
 pub use hir_def::db::{
-    DefDatabase2, DefDatabase2Storage, EnumDataQuery, InternDatabase, InternDatabaseStorage,
-    RawItemsQuery, RawItemsWithSourceMapQuery, StructDataQuery,
+    CrateDefMapQuery, DefDatabase2, DefDatabase2Storage, EnumDataQuery, InternDatabase,
+    InternDatabaseStorage, RawItemsQuery, RawItemsWithSourceMapQuery, StructDataQuery,
 };
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
@@ -41,9 +40,6 @@ pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
     #[salsa::invoke(crate::traits::TraitItemsIndex::trait_items_index)]
     fn trait_items_index(&self, module: Module) -> crate::traits::TraitItemsIndex;
 
-    #[salsa::invoke(CrateDefMap::crate_def_map_query)]
-    fn crate_def_map(&self, krate: Crate) -> Arc<CrateDefMap>;
-
     #[salsa::invoke(ModuleImplBlocks::impls_in_module_with_source_map_query)]
     fn impls_in_module_with_source_map(
         &self,
diff --git a/crates/ra_hir/src/diagnostics.rs b/crates/ra_hir/src/diagnostics.rs
index a33af8f46..1751e7be3 100644
--- a/crates/ra_hir/src/diagnostics.rs
+++ b/crates/ra_hir/src/diagnostics.rs
@@ -3,10 +3,10 @@
 use std::any::Any;
 
 use ra_syntax::{ast, AstNode, AstPtr, SyntaxNodePtr};
-use relative_path::RelativePathBuf;
 
 use crate::{db::AstDatabase, HirFileId, Name, Source};
 
+pub use hir_def::diagnostics::UnresolvedModule;
 pub use hir_expand::diagnostics::{AstDiagnostic, Diagnostic, DiagnosticSink};
 
 #[derive(Debug)]
@@ -30,25 +30,6 @@ impl Diagnostic for NoSuchField {
 }
 
 #[derive(Debug)]
-pub struct UnresolvedModule {
-    pub file: HirFileId,
-    pub decl: AstPtr<ast::Module>,
-    pub candidate: RelativePathBuf,
-}
-
-impl Diagnostic for UnresolvedModule {
-    fn message(&self) -> String {
-        "unresolved module".to_string()
-    }
-    fn source(&self) -> Source<SyntaxNodePtr> {
-        Source { file_id: self.file, ast: self.decl.into() }
-    }
-    fn as_any(&self) -> &(dyn Any + Send + 'static) {
-        self
-    }
-}
-
-#[derive(Debug)]
 pub struct MissingFields {
     pub file: HirFileId,
     pub field_list: AstPtr<ast::RecordFieldList>,
diff --git a/crates/ra_hir/src/from_id.rs b/crates/ra_hir/src/from_id.rs
new file mode 100644
index 000000000..089dbc908
--- /dev/null
+++ b/crates/ra_hir/src/from_id.rs
@@ -0,0 +1,63 @@
+//! Utility module for converting between hir_def ids and code_model wrappers.
+//!
+//! It's unclear if we need this long-term, but it's definitelly useful while we
+//! are splitting the hir.
+
+use hir_def::{AdtId, EnumVariantId, ModuleDefId};
+
+use crate::{Adt, EnumVariant, ModuleDef};
+
+macro_rules! from_id {
+    ($(($id:path, $ty:path)),*) => {$(
+        impl From<$id> for $ty {
+            fn from(id: $id) -> $ty {
+                $ty { id }
+            }
+        }
+    )*}
+}
+
+from_id![
+    (hir_def::ModuleId, crate::Module),
+    (hir_def::StructId, crate::Struct),
+    (hir_def::UnionId, crate::Union),
+    (hir_def::EnumId, crate::Enum),
+    (hir_def::TypeAliasId, crate::TypeAlias),
+    (hir_def::TraitId, crate::Trait),
+    (hir_def::StaticId, crate::Static),
+    (hir_def::ConstId, crate::Const),
+    (hir_def::FunctionId, crate::Function),
+    (hir_expand::MacroDefId, crate::MacroDef)
+];
+
+impl From<AdtId> for Adt {
+    fn from(id: AdtId) -> Self {
+        match id {
+            AdtId::StructId(it) => Adt::Struct(it.into()),
+            AdtId::UnionId(it) => Adt::Union(it.into()),
+            AdtId::EnumId(it) => Adt::Enum(it.into()),
+        }
+    }
+}
+
+impl From<EnumVariantId> for EnumVariant {
+    fn from(id: EnumVariantId) -> Self {
+        EnumVariant { parent: id.parent.into(), id: id.local_id }
+    }
+}
+
+impl From<ModuleDefId> for ModuleDef {
+    fn from(id: ModuleDefId) -> Self {
+        match id {
+            ModuleDefId::ModuleId(it) => ModuleDef::Module(it.into()),
+            ModuleDefId::FunctionId(it) => ModuleDef::Function(it.into()),
+            ModuleDefId::AdtId(it) => ModuleDef::Adt(it.into()),
+            ModuleDefId::EnumVariantId(it) => ModuleDef::EnumVariant(it.into()),
+            ModuleDefId::ConstId(it) => ModuleDef::Const(it.into()),
+            ModuleDefId::StaticId(it) => ModuleDef::Static(it.into()),
+            ModuleDefId::TraitId(it) => ModuleDef::Trait(it.into()),
+            ModuleDefId::TypeAliasId(it) => ModuleDef::TypeAlias(it.into()),
+            ModuleDefId::BuiltinType(it) => ModuleDef::BuiltinType(it),
+        }
+    }
+}
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index a9de01455..9899bdbbc 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -149,14 +149,20 @@ impl Module {
             ModuleSource::SourceFile(_) => None,
         };
 
-        db.relevant_crates(src.file_id.original_file(db))
-            .iter()
-            .map(|&crate_id| Crate { crate_id })
-            .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::new(krate, module_id))
-            })
+        db.relevant_crates(src.file_id.original_file(db)).iter().find_map(|&crate_id| {
+            let def_map = db.crate_def_map(crate_id);
+
+            let (module_id, _module_data) =
+                def_map.modules.iter().find(|(_module_id, module_data)| {
+                    if decl_id.is_some() {
+                        module_data.declaration == decl_id
+                    } else {
+                        module_data.definition.map(|it| it.into()) == Some(src.file_id)
+                    }
+                })?;
+
+            Some(Module::new(Crate { crate_id }, module_id))
+        })
     }
 }
 
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 0ba17e571..3ba99d92d 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -34,7 +34,6 @@ pub mod mock;
 pub mod source_binder;
 
 mod ids;
-mod nameres;
 mod adt;
 mod traits;
 mod type_alias;
@@ -47,6 +46,7 @@ mod resolve;
 pub mod diagnostics;
 mod util;
 
+mod from_id;
 mod code_model;
 
 pub mod from_source;
@@ -72,7 +72,6 @@ pub use crate::{
     generics::{GenericDef, GenericParam, GenericParams, HasGenericParams},
     ids::{HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFile},
     impl_block::ImplBlock,
-    nameres::{ImportId, Namespace, PerNs},
     resolve::ScopeDef,
     source_binder::{PathResolution, ScopeEntryWithSyntax, SourceAnalyzer},
     ty::{
@@ -82,6 +81,10 @@ pub use crate::{
 
 pub use hir_def::{
     builtin_type::BuiltinType,
+    nameres::{
+        per_ns::{Namespace, PerNs},
+        raw::ImportId,
+    },
     path::{Path, PathKind},
     type_ref::Mutability,
 };
diff --git a/crates/ra_hir/src/marks.rs b/crates/ra_hir/src/marks.rs
index b423489a1..0d4fa5b67 100644
--- a/crates/ra_hir/src/marks.rs
+++ b/crates/ra_hir/src/marks.rs
@@ -1,21 +1,10 @@
 //! See test_utils/src/marks.rs
 
 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
     type_var_cycles_resolve_as_possible
     type_var_resolves_to_int_var
-    glob_enum
-    glob_across_crates
-    std_prelude
     match_ergonomics_ref
     infer_while_let
-    macro_rules_from_other_crates_are_visible_with_macro_use
-    prelude_is_macro_use
     coerce_merge_fail_fallback
-    macro_dollar_crate_self
-    macro_dollar_crate_other
 );
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 4c89c8d38..ab97a09b9 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -7,9 +7,8 @@ use parking_lot::Mutex;
 use ra_cfg::CfgOptions;
 use ra_db::{
     salsa, CrateGraph, CrateId, Edition, FileId, FileLoader, FileLoaderDelegate, FilePosition,
-    SourceDatabase, SourceDatabaseExt, SourceRoot, SourceRootId,
+    RelativePath, RelativePathBuf, SourceDatabase, SourceDatabaseExt, SourceRoot, SourceRootId,
 };
-use relative_path::{RelativePath, RelativePathBuf};
 use rustc_hash::FxHashMap;
 use test_utils::{extract_offset, parse_fixture, CURSOR_MARKER};
 
@@ -78,12 +77,6 @@ impl MockDatabase {
         (db, source_root, file_id)
     }
 
-    pub fn with_position(fixture: &str) -> (MockDatabase, FilePosition) {
-        let (db, position) = MockDatabase::from_fixture(fixture);
-        let position = position.expect("expected a marker ( <|> )");
-        (db, position)
-    }
-
     pub fn file_id_of(&self, path: &str) -> FileId {
         match self.files.get(path) {
             Some(it) => *it,
@@ -91,25 +84,6 @@ impl MockDatabase {
         }
     }
 
-    pub fn set_crate_graph_from_fixture(&mut self, graph: CrateGraphFixture) {
-        let mut ids = FxHashMap::default();
-        let mut crate_graph = CrateGraph::default();
-        for (crate_name, (crate_root, edition, cfg_options, _)) in graph.0.iter() {
-            let crate_root = self.file_id_of(&crate_root);
-            let crate_id = crate_graph.add_crate_root(crate_root, *edition, cfg_options.clone());
-            Arc::make_mut(&mut self.crate_names).insert(crate_id, crate_name.clone());
-            ids.insert(crate_name, crate_id);
-        }
-        for (crate_name, (_, _, _, deps)) in graph.0.iter() {
-            let from = ids[crate_name];
-            for dep in deps {
-                let to = ids[dep];
-                crate_graph.add_dep(from, dep.as_str().into(), to).unwrap();
-            }
-        }
-        self.set_crate_graph(Arc::new(crate_graph))
-    }
-
     pub fn diagnostics(&self) -> String {
         let mut buf = String::new();
         let mut files: Vec<FileId> = self.files.values().copied().collect();
@@ -286,46 +260,3 @@ impl MockDatabase {
             .collect()
     }
 }
-
-#[derive(Default)]
-pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, CfgOptions, Vec<String>))>);
-
-#[macro_export]
-macro_rules! crate_graph {
-    ($(
-        $crate_name:literal: (
-            $crate_path:literal,
-            $($edition:literal,)?
-            [$($dep:literal),*]
-            $(, cfg = {
-                $($key:literal $(= $value:literal)?),*
-                $(,)?
-            })?
-        ),
-    )*) => {{
-        let mut res = $crate::mock::CrateGraphFixture::default();
-        $(
-            #[allow(unused_mut, unused_assignments)]
-            let mut edition = ra_db::Edition::Edition2018;
-            $(edition = ra_db::Edition::from_string($edition);)?
-            let cfg_options = {
-                #[allow(unused_mut)]
-                let mut cfg = ::ra_cfg::CfgOptions::default();
-                $(
-                    $(
-                        if 0 == 0 $(+ { drop($value); 1})? {
-                            cfg.insert_atom($key.into());
-                        }
-                        $(cfg.insert_key_value($key.into(), $value.into());)?
-                    )*
-                )?
-                cfg
-            };
-            res.0.push((
-                $crate_name.to_string(),
-                ($crate_path.to_string(), edition, cfg_options, vec![$($dep.to_string()),*])
-            ));
-        )*
-        res
-    }}
-}
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
deleted file mode 100644
index 32a6ab474..000000000
--- a/crates/ra_hir/src/nameres.rs
+++ /dev/null
@@ -1,558 +0,0 @@
-//! This module implements import-resolution/macro expansion algorithm.
-//!
-//! The result of this module is `CrateDefMap`: a data structure which contains:
-//!
-//!   * a tree of modules for the crate
-//!   * for each module, a set of items visible in the module (directly declared
-//!     or imported)
-//!
-//! Note that `CrateDefMap` contains fully macro expanded code.
-//!
-//! Computing `CrateDefMap` can be partitioned into several logically
-//! independent "phases". The phases are mutually recursive though, there's no
-//! strict ordering.
-//!
-//! ## Collecting RawItems
-//!
-//!  This happens in the `raw` module, which parses a single source file into a
-//!  set of top-level items. Nested imports are desugared to flat imports in
-//!  this phase. Macro calls are represented as a triple of (Path, Option<Name>,
-//!  TokenTree).
-//!
-//! ## Collecting Modules
-//!
-//! This happens in the `collector` module. In this phase, we recursively walk
-//! tree of modules, collect raw items from submodules, populate module scopes
-//! with defined items (so, we assign item ids in this phase) and record the set
-//! of unresolved imports and macros.
-//!
-//! While we walk tree of modules, we also record macro_rules definitions and
-//! expand calls to macro_rules defined macros.
-//!
-//! ## Resolving Imports
-//!
-//! We maintain a list of currently unresolved imports. On every iteration, we
-//! try to resolve some imports from this list. If the import is resolved, we
-//! record it, by adding an item to current module scope and, if necessary, by
-//! recursively populating glob imports.
-//!
-//! ## Resolving Macros
-//!
-//! macro_rules from the same crate use a global mutable namespace. We expand
-//! them immediately, when we collect modules.
-//!
-//! Macros from other crates (including proc-macros) can be used with
-//! `foo::bar!` syntax. We handle them similarly to imports. There's a list of
-//! unexpanded macros. On every iteration, we try to resolve each macro call
-//! path and, upon success, we run macro expansion and "collect module" phase
-//! on the result
-
-mod per_ns;
-mod collector;
-#[cfg(test)]
-mod tests;
-
-use std::sync::Arc;
-
-use hir_def::{builtin_type::BuiltinType, CrateModuleId};
-use hir_expand::diagnostics::DiagnosticSink;
-use once_cell::sync::Lazy;
-use ra_arena::Arena;
-use ra_db::{Edition, FileId};
-use ra_prof::profile;
-use ra_syntax::ast;
-use rustc_hash::{FxHashMap, FxHashSet};
-use test_utils::tested_by;
-
-use crate::{
-    db::{AstDatabase, DefDatabase},
-    ids::MacroDefId,
-    nameres::diagnostics::DefDiagnostic,
-    Adt, AstId, Crate, HirFileId, MacroDef, Module, ModuleDef, Name, Path, PathKind, Trait,
-};
-
-pub use self::per_ns::{Namespace, PerNs};
-
-pub use hir_def::nameres::raw::ImportId;
-
-/// Contains all top-level defs from a macro-expanded crate
-#[derive(Debug, PartialEq, Eq)]
-pub struct CrateDefMap {
-    krate: Crate,
-    edition: Edition,
-    /// The prelude module for this crate. This either comes from an import
-    /// marked with the `prelude_import` attribute, or (in the normal case) from
-    /// a dependency (`std` or `core`).
-    prelude: Option<Module>,
-    extern_prelude: FxHashMap<Name, ModuleDef>,
-    root: CrateModuleId,
-    modules: Arena<CrateModuleId, ModuleData>,
-
-    /// Some macros are not well-behavior, which leads to infinite loop
-    /// e.g. macro_rules! foo { ($ty:ty) => { foo!($ty); } }
-    /// We mark it down and skip it in collector
-    ///
-    /// FIXME:
-    /// Right now it only handle a poison macro in a single crate,
-    /// such that if other crate try to call that macro,
-    /// the whole process will do again until it became poisoned in that crate.
-    /// We should handle this macro set globally
-    /// However, do we want to put it as a global variable?
-    poison_macros: FxHashSet<MacroDefId>,
-
-    diagnostics: Vec<DefDiagnostic>,
-}
-
-impl std::ops::Index<CrateModuleId> for CrateDefMap {
-    type Output = ModuleData;
-    fn index(&self, id: CrateModuleId) -> &ModuleData {
-        &self.modules[id]
-    }
-}
-
-#[derive(Default, Debug, PartialEq, Eq)]
-pub struct ModuleData {
-    pub(crate) parent: Option<CrateModuleId>,
-    pub(crate) children: FxHashMap<Name, CrateModuleId>,
-    pub(crate) scope: ModuleScope,
-    /// None for root
-    pub(crate) declaration: Option<AstId<ast::Module>>,
-    /// None for inline modules.
-    ///
-    /// Note that non-inline modules, by definition, live inside non-macro file.
-    pub(crate) definition: Option<FileId>,
-}
-
-#[derive(Debug, Default, PartialEq, Eq, Clone)]
-pub struct ModuleScope {
-    items: FxHashMap<Name, Resolution>,
-    /// Macros visable in current module in legacy textual scope
-    ///
-    /// For macros invoked by an unquatified identifier like `bar!()`, `legacy_macros` will be searched in first.
-    /// If it yields no result, then it turns to module scoped `macros`.
-    /// It macros with name quatified with a path like `crate::foo::bar!()`, `legacy_macros` will be skipped,
-    /// and only normal scoped `macros` will be searched in.
-    ///
-    /// Note that this automatically inherit macros defined textually before the definition of module itself.
-    ///
-    /// Module scoped macros will be inserted into `items` instead of here.
-    // FIXME: Macro shadowing in one module is not properly handled. Non-item place macros will
-    // be all resolved to the last one defined if shadowing happens.
-    legacy_macros: FxHashMap<Name, MacroDef>,
-}
-
-static BUILTIN_SCOPE: Lazy<FxHashMap<Name, Resolution>> = Lazy::new(|| {
-    BuiltinType::ALL
-        .iter()
-        .map(|(name, ty)| {
-            (name.clone(), Resolution { def: PerNs::types(ty.clone().into()), import: None })
-        })
-        .collect()
-});
-
-/// Legacy macros can only be accessed through special methods like `get_legacy_macros`.
-/// Other methods will only resolve values, types and module scoped macros only.
-impl ModuleScope {
-    pub fn entries<'a>(&'a self) -> impl Iterator<Item = (&'a Name, &'a Resolution)> + 'a {
-        //FIXME: shadowing
-        self.items.iter().chain(BUILTIN_SCOPE.iter())
-    }
-
-    /// Iterate over all module scoped macros
-    pub fn macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDef)> + 'a {
-        self.items
-            .iter()
-            .filter_map(|(name, res)| res.def.get_macros().map(|macro_| (name, macro_)))
-    }
-
-    /// Iterate over all legacy textual scoped macros visable at the end of the module
-    pub fn legacy_macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDef)> + 'a {
-        self.legacy_macros.iter().map(|(name, def)| (name, *def))
-    }
-
-    /// Get a name from current module scope, legacy macros are not included
-    pub fn get(&self, name: &Name) -> Option<&Resolution> {
-        self.items.get(name).or_else(|| BUILTIN_SCOPE.get(name))
-    }
-
-    pub fn traits<'a>(&'a self) -> impl Iterator<Item = Trait> + 'a {
-        self.items.values().filter_map(|r| match r.def.take_types() {
-            Some(ModuleDef::Trait(t)) => Some(t),
-            _ => None,
-        })
-    }
-
-    fn get_legacy_macro(&self, name: &Name) -> Option<MacroDef> {
-        self.legacy_macros.get(name).copied()
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Default)]
-pub struct Resolution {
-    /// None for unresolved
-    pub def: PerNs,
-    /// ident by which this is imported into local scope.
-    pub import: Option<ImportId>,
-}
-
-impl Resolution {
-    pub(crate) fn from_macro(macro_: MacroDef) -> Self {
-        Resolution { def: PerNs::macros(macro_), import: None }
-    }
-}
-
-#[derive(Debug, Clone)]
-struct ResolvePathResult {
-    resolved_def: PerNs,
-    segment_index: Option<usize>,
-    reached_fixedpoint: ReachedFixedPoint,
-}
-
-impl ResolvePathResult {
-    fn empty(reached_fixedpoint: ReachedFixedPoint) -> ResolvePathResult {
-        ResolvePathResult::with(PerNs::none(), reached_fixedpoint, None)
-    }
-
-    fn with(
-        resolved_def: PerNs,
-        reached_fixedpoint: ReachedFixedPoint,
-        segment_index: Option<usize>,
-    ) -> ResolvePathResult {
-        ResolvePathResult { resolved_def, reached_fixedpoint, segment_index }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-enum ResolveMode {
-    Import,
-    Other,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-enum ReachedFixedPoint {
-    Yes,
-    No,
-}
-
-impl CrateDefMap {
-    pub(crate) fn crate_def_map_query(
-        // Note that this doesn't have `+ AstDatabase`!
-        // This gurantess that `CrateDefMap` is stable across reparses.
-        db: &impl DefDatabase,
-        krate: Crate,
-    ) -> Arc<CrateDefMap> {
-        let _p = profile("crate_def_map_query");
-        let def_map = {
-            let edition = krate.edition(db);
-            let mut modules: Arena<CrateModuleId, ModuleData> = Arena::default();
-            let root = modules.alloc(ModuleData::default());
-            CrateDefMap {
-                krate,
-                edition,
-                extern_prelude: FxHashMap::default(),
-                prelude: None,
-                root,
-                modules,
-                poison_macros: FxHashSet::default(),
-                diagnostics: Vec::new(),
-            }
-        };
-        let def_map = collector::collect_defs(db, def_map);
-        Arc::new(def_map)
-    }
-
-    pub(crate) fn krate(&self) -> Crate {
-        self.krate
-    }
-
-    pub(crate) fn root(&self) -> CrateModuleId {
-        self.root
-    }
-
-    pub(crate) fn prelude(&self) -> Option<Module> {
-        self.prelude
-    }
-
-    pub(crate) fn extern_prelude(&self) -> &FxHashMap<Name, ModuleDef> {
-        &self.extern_prelude
-    }
-
-    pub(crate) fn add_diagnostics(
-        &self,
-        db: &(impl DefDatabase + AstDatabase),
-        module: CrateModuleId,
-        sink: &mut DiagnosticSink,
-    ) {
-        self.diagnostics.iter().for_each(|it| it.add_to(db, module, sink))
-    }
-
-    pub(crate) fn find_module_by_source(
-        &self,
-        file_id: HirFileId,
-        decl_id: Option<AstId<ast::Module>>,
-    ) -> Option<CrateModuleId> {
-        let (module_id, _module_data) = self.modules.iter().find(|(_module_id, module_data)| {
-            if decl_id.is_some() {
-                module_data.declaration == decl_id
-            } else {
-                module_data.definition.map(|it| it.into()) == Some(file_id)
-            }
-        })?;
-        Some(module_id)
-    }
-
-    pub(crate) fn resolve_path(
-        &self,
-        db: &impl DefDatabase,
-        original_module: CrateModuleId,
-        path: &Path,
-    ) -> (PerNs, Option<usize>) {
-        let res = self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path);
-        (res.resolved_def, res.segment_index)
-    }
-
-    // Returns Yes if we are sure that additions to `ItemMap` wouldn't change
-    // the result.
-    fn resolve_path_fp_with_macro(
-        &self,
-        db: &impl DefDatabase,
-        mode: ResolveMode,
-        original_module: CrateModuleId,
-        path: &Path,
-    ) -> ResolvePathResult {
-        let mut segments = path.segments.iter().enumerate();
-        let mut curr_per_ns: PerNs = match path.kind {
-            PathKind::DollarCrate(crate_id) => {
-                let krate = Crate { crate_id };
-                if krate == self.krate {
-                    tested_by!(macro_dollar_crate_self);
-                    PerNs::types(Module::new(self.krate, self.root).into())
-                } else {
-                    match krate.root_module(db) {
-                        Some(module) => {
-                            tested_by!(macro_dollar_crate_other);
-                            PerNs::types(module.into())
-                        }
-                        None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
-                    }
-                }
-            }
-            PathKind::Crate => PerNs::types(Module::new(self.krate, self.root).into()),
-            PathKind::Self_ => PerNs::types(Module::new(self.krate, 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)
-            // FIXME there must be a nicer way to write this condition
-            PathKind::Plain | PathKind::Abs
-                if self.edition == Edition::Edition2015
-                    && (path.kind == PathKind::Abs || mode == ResolveMode::Import) =>
-            {
-                let segment = match segments.next() {
-                    Some((_, segment)) => segment,
-                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
-                };
-                log::debug!("resolving {:?} in crate root (+ extern prelude)", segment);
-                self.resolve_name_in_crate_root_or_extern_prelude(&segment.name)
-            }
-            PathKind::Plain => {
-                let segment = match segments.next() {
-                    Some((_, segment)) => segment,
-                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
-                };
-                log::debug!("resolving {:?} in module", segment);
-                self.resolve_name_in_module(db, original_module, &segment.name)
-            }
-            PathKind::Super => {
-                if let Some(p) = self.modules[original_module].parent {
-                    PerNs::types(Module::new(self.krate, p).into())
-                } else {
-                    log::debug!("super path in root module");
-                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
-                }
-            }
-            PathKind::Abs => {
-                // 2018-style absolute path -- only extern prelude
-                let segment = match segments.next() {
-                    Some((_, segment)) => segment,
-                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
-                };
-                if let Some(def) = self.extern_prelude.get(&segment.name) {
-                    log::debug!("absolute path {:?} resolved to crate {:?}", path, def);
-                    PerNs::types(*def)
-                } else {
-                    return ResolvePathResult::empty(ReachedFixedPoint::No); // extern crate declarations can add to the extern prelude
-                }
-            }
-            PathKind::Type(_) => {
-                // This is handled in `infer::infer_path_expr`
-                // The result returned here does not matter
-                return ResolvePathResult::empty(ReachedFixedPoint::Yes);
-            }
-        };
-
-        for (i, segment) in segments {
-            let curr = match curr_per_ns.take_types() {
-                Some(r) => r,
-                None => {
-                    // we still have path segments left, but the path so far
-                    // didn't resolve in the types namespace => no resolution
-                    // (don't break here because `curr_per_ns` might contain
-                    // something in the value namespace, and it would be wrong
-                    // to return that)
-                    return ResolvePathResult::empty(ReachedFixedPoint::No);
-                }
-            };
-            // resolve segment in curr
-
-            curr_per_ns = match curr {
-                ModuleDef::Module(module) => {
-                    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 (def, s) = defp_map.resolve_path(db, module.id.module_id, &path);
-                        return ResolvePathResult::with(
-                            def,
-                            ReachedFixedPoint::Yes,
-                            s.map(|s| s + i),
-                        );
-                    }
-
-                    // Since it is a qualified path here, it should not contains legacy macros
-                    match self[module.id.module_id].scope.get(&segment.name) {
-                        Some(res) => res.def,
-                        _ => {
-                            log::debug!("path segment {:?} not found", segment.name);
-                            return ResolvePathResult::empty(ReachedFixedPoint::No);
-                        }
-                    }
-                }
-                ModuleDef::Adt(Adt::Enum(e)) => {
-                    // enum variant
-                    tested_by!(can_import_enum_variant);
-                    match e.variant(db, &segment.name) {
-                        Some(variant) => PerNs::both(variant.into(), variant.into()),
-                        None => {
-                            return ResolvePathResult::with(
-                                PerNs::types(e.into()),
-                                ReachedFixedPoint::Yes,
-                                Some(i),
-                            );
-                        }
-                    }
-                }
-                s => {
-                    // could be an inherent method call in UFCS form
-                    // (`Struct::method`), or some other kind of associated item
-                    log::debug!(
-                        "path segment {:?} resolved to non-module {:?}, but is not last",
-                        segment.name,
-                        curr,
-                    );
-
-                    return ResolvePathResult::with(
-                        PerNs::types(s),
-                        ReachedFixedPoint::Yes,
-                        Some(i),
-                    );
-                }
-            };
-        }
-        ResolvePathResult::with(curr_per_ns, ReachedFixedPoint::Yes, None)
-    }
-
-    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> PerNs {
-        let from_crate_root =
-            self[self.root].scope.get(name).map_or_else(PerNs::none, |res| res.def);
-        let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
-
-        from_crate_root.or(from_extern_prelude)
-    }
-
-    pub(crate) fn resolve_name_in_module(
-        &self,
-        db: &impl DefDatabase,
-        module: CrateModuleId,
-        name: &Name,
-    ) -> PerNs {
-        // Resolve in:
-        //  - legacy scope of macro
-        //  - current module / scope
-        //  - extern prelude
-        //  - std prelude
-        let from_legacy_macro =
-            self[module].scope.get_legacy_macro(name).map_or_else(PerNs::none, PerNs::macros);
-        let from_scope = self[module].scope.get(name).map_or_else(PerNs::none, |res| res.def);
-        let from_extern_prelude =
-            self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it));
-        let from_prelude = self.resolve_in_prelude(db, name);
-
-        from_legacy_macro.or(from_scope).or(from_extern_prelude).or(from_prelude)
-    }
-
-    fn resolve_name_in_extern_prelude(&self, name: &Name) -> PerNs {
-        self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it))
-    }
-
-    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 {
-                self
-            } else {
-                // Extend lifetime
-                keep = db.crate_def_map(prelude.krate());
-                &keep
-            };
-            def_map[prelude.id.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
-        } else {
-            PerNs::none()
-        }
-    }
-}
-
-mod diagnostics {
-    use hir_expand::diagnostics::DiagnosticSink;
-    use ra_syntax::{ast, AstPtr};
-    use relative_path::RelativePathBuf;
-
-    use crate::{
-        db::{AstDatabase, DefDatabase},
-        diagnostics::UnresolvedModule,
-        nameres::CrateModuleId,
-        AstId,
-    };
-
-    #[derive(Debug, PartialEq, Eq)]
-    pub(super) enum DefDiagnostic {
-        UnresolvedModule {
-            module: CrateModuleId,
-            declaration: AstId<ast::Module>,
-            candidate: RelativePathBuf,
-        },
-    }
-
-    impl DefDiagnostic {
-        pub(super) fn add_to(
-            &self,
-            db: &(impl DefDatabase + AstDatabase),
-            target_module: CrateModuleId,
-            sink: &mut DiagnosticSink,
-        ) {
-            match self {
-                DefDiagnostic::UnresolvedModule { module, declaration, candidate } => {
-                    if *module != target_module {
-                        return;
-                    }
-                    let decl = declaration.to_node(db);
-                    sink.push(UnresolvedModule {
-                        file: declaration.file_id(),
-                        decl: AstPtr::new(&decl),
-                        candidate: candidate.clone(),
-                    })
-                }
-            }
-        }
-    }
-}
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index 75b24d386..b932b0c8c 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -3,8 +3,9 @@ use std::sync::Arc;
 
 use hir_def::{
     builtin_type::BuiltinType,
+    nameres::CrateDefMap,
     path::{Path, PathKind},
-    CrateModuleId,
+    AdtId, CrateModuleId, ModuleDefId,
 };
 use hir_expand::name::{self, Name};
 use rustc_hash::FxHashSet;
@@ -18,8 +19,8 @@ use crate::{
     },
     generics::GenericParams,
     impl_block::ImplBlock,
-    nameres::{CrateDefMap, PerNs},
-    Adt, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, Static, Struct, Trait, TypeAlias,
+    Adt, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, PerNs, Static, Struct, Trait,
+    TypeAlias,
 };
 
 #[derive(Debug, Clone, Default)]
@@ -90,7 +91,7 @@ impl Resolver {
     pub(crate) fn resolve_known_trait(&self, db: &impl HirDatabase, path: &Path) -> Option<Trait> {
         let res = self.resolve_module_path(db, path).take_types()?;
         match res {
-            ModuleDef::Trait(it) => Some(it),
+            ModuleDefId::TraitId(it) => Some(it.into()),
             _ => None,
         }
     }
@@ -103,7 +104,7 @@ impl Resolver {
     ) -> Option<Struct> {
         let res = self.resolve_module_path(db, path).take_types()?;
         match res {
-            ModuleDef::Adt(Adt::Struct(it)) => Some(it),
+            ModuleDefId::AdtId(AdtId::StructId(it)) => Some(it.into()),
             _ => None,
         }
     }
@@ -112,7 +113,7 @@ impl Resolver {
     pub(crate) fn resolve_known_enum(&self, db: &impl HirDatabase, path: &Path) -> Option<Enum> {
         let res = self.resolve_module_path(db, path).take_types()?;
         match res {
-            ModuleDef::Adt(Adt::Enum(it)) => Some(it),
+            ModuleDefId::AdtId(AdtId::EnumId(it)) => Some(it.into()),
             _ => None,
         }
     }
@@ -166,18 +167,18 @@ impl Resolver {
                 Scope::ModuleScope(m) => {
                     let (module_def, idx) = m.crate_def_map.resolve_path(db, m.module_id, path);
                     let res = match module_def.take_types()? {
-                        ModuleDef::Adt(it) => TypeNs::Adt(it),
-                        ModuleDef::EnumVariant(it) => TypeNs::EnumVariant(it),
+                        ModuleDefId::AdtId(it) => TypeNs::Adt(it.into()),
+                        ModuleDefId::EnumVariantId(it) => TypeNs::EnumVariant(it.into()),
 
-                        ModuleDef::TypeAlias(it) => TypeNs::TypeAlias(it),
-                        ModuleDef::BuiltinType(it) => TypeNs::BuiltinType(it),
+                        ModuleDefId::TypeAliasId(it) => TypeNs::TypeAlias(it.into()),
+                        ModuleDefId::BuiltinType(it) => TypeNs::BuiltinType(it),
 
-                        ModuleDef::Trait(it) => TypeNs::Trait(it),
+                        ModuleDefId::TraitId(it) => TypeNs::Trait(it.into()),
 
-                        ModuleDef::Function(_)
-                        | ModuleDef::Const(_)
-                        | ModuleDef::Static(_)
-                        | ModuleDef::Module(_) => return None,
+                        ModuleDefId::FunctionId(_)
+                        | ModuleDefId::ConstId(_)
+                        | ModuleDefId::StaticId(_)
+                        | ModuleDefId::ModuleId(_) => return None,
                     };
                     return Some((res, idx));
                 }
@@ -261,33 +262,35 @@ impl Resolver {
                     return match idx {
                         None => {
                             let value = match module_def.take_values()? {
-                                ModuleDef::Function(it) => ValueNs::Function(it),
-                                ModuleDef::Adt(Adt::Struct(it)) => ValueNs::Struct(it),
-                                ModuleDef::EnumVariant(it) => ValueNs::EnumVariant(it),
-                                ModuleDef::Const(it) => ValueNs::Const(it),
-                                ModuleDef::Static(it) => ValueNs::Static(it),
-
-                                ModuleDef::Adt(Adt::Enum(_))
-                                | ModuleDef::Adt(Adt::Union(_))
-                                | ModuleDef::Trait(_)
-                                | ModuleDef::TypeAlias(_)
-                                | ModuleDef::BuiltinType(_)
-                                | ModuleDef::Module(_) => return None,
+                                ModuleDefId::FunctionId(it) => ValueNs::Function(it.into()),
+                                ModuleDefId::AdtId(AdtId::StructId(it)) => {
+                                    ValueNs::Struct(it.into())
+                                }
+                                ModuleDefId::EnumVariantId(it) => ValueNs::EnumVariant(it.into()),
+                                ModuleDefId::ConstId(it) => ValueNs::Const(it.into()),
+                                ModuleDefId::StaticId(it) => ValueNs::Static(it.into()),
+
+                                ModuleDefId::AdtId(AdtId::EnumId(_))
+                                | ModuleDefId::AdtId(AdtId::UnionId(_))
+                                | ModuleDefId::TraitId(_)
+                                | ModuleDefId::TypeAliasId(_)
+                                | ModuleDefId::BuiltinType(_)
+                                | ModuleDefId::ModuleId(_) => return None,
                             };
                             Some(ResolveValueResult::ValueNs(value))
                         }
                         Some(idx) => {
                             let ty = match module_def.take_types()? {
-                                ModuleDef::Adt(it) => TypeNs::Adt(it),
-                                ModuleDef::Trait(it) => TypeNs::Trait(it),
-                                ModuleDef::TypeAlias(it) => TypeNs::TypeAlias(it),
-                                ModuleDef::BuiltinType(it) => TypeNs::BuiltinType(it),
-
-                                ModuleDef::Module(_)
-                                | ModuleDef::Function(_)
-                                | ModuleDef::EnumVariant(_)
-                                | ModuleDef::Const(_)
-                                | ModuleDef::Static(_) => return None,
+                                ModuleDefId::AdtId(it) => TypeNs::Adt(it.into()),
+                                ModuleDefId::TraitId(it) => TypeNs::Trait(it.into()),
+                                ModuleDefId::TypeAliasId(it) => TypeNs::TypeAlias(it.into()),
+                                ModuleDefId::BuiltinType(it) => TypeNs::BuiltinType(it),
+
+                                ModuleDefId::ModuleId(_)
+                                | ModuleDefId::FunctionId(_)
+                                | ModuleDefId::EnumVariantId(_)
+                                | ModuleDefId::ConstId(_)
+                                | ModuleDefId::StaticId(_) => return None,
                             };
                             Some(ResolveValueResult::Partial(ty, idx))
                         }
@@ -315,7 +318,7 @@ impl Resolver {
         path: &Path,
     ) -> Option<MacroDef> {
         let (item_map, module) = self.module()?;
-        item_map.resolve_path(db, module, path).0.get_macros()
+        item_map.resolve_path(db, module, path).0.get_macros().map(MacroDef::from)
     }
 
     pub(crate) fn process_all_names(
@@ -333,10 +336,11 @@ 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());
-                    traits.extend(prelude_def_map[prelude.id.module_id].scope.traits());
+                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    traits
+                        .extend(prelude_def_map[prelude.module_id].scope.traits().map(Trait::from));
                 }
-                traits.extend(m.crate_def_map[m.module_id].scope.traits());
+                traits.extend(m.crate_def_map[m.module_id].scope.traits().map(Trait::from));
             }
         }
         traits
@@ -351,7 +355,7 @@ impl Resolver {
     }
 
     pub(crate) fn krate(&self) -> Option<Crate> {
-        self.module().map(|t| t.0.krate())
+        self.module().map(|t| Crate { crate_id: t.0.krate() })
     }
 
     pub(crate) fn where_predicates_in_scope<'a>(
@@ -420,8 +424,10 @@ impl From<PerNs> for ScopeDef {
     fn from(def: PerNs) -> Self {
         def.take_types()
             .or_else(|| def.take_values())
-            .map(ScopeDef::ModuleDef)
-            .or_else(|| def.get_macros().map(ScopeDef::MacroDef))
+            .map(|module_def_id| ScopeDef::ModuleDef(module_def_id.into()))
+            .or_else(|| {
+                def.get_macros().map(|macro_def_id| ScopeDef::MacroDef(macro_def_id.into()))
+            })
             .unwrap_or(ScopeDef::Unknown)
     }
 }
@@ -441,18 +447,16 @@ impl Scope {
                     f(name.clone(), res.def.into());
                 });
                 m.crate_def_map[m.module_id].scope.legacy_macros().for_each(|(name, macro_)| {
-                    f(name.clone(), ScopeDef::MacroDef(macro_));
+                    f(name.clone(), ScopeDef::MacroDef(macro_.into()));
                 });
-                m.crate_def_map.extern_prelude().iter().for_each(|(name, def)| {
-                    f(name.clone(), ScopeDef::ModuleDef(*def));
+                m.crate_def_map.extern_prelude().iter().for_each(|(name, &def)| {
+                    f(name.clone(), ScopeDef::ModuleDef(def.into()));
                 });
                 if let Some(prelude) = m.crate_def_map.prelude() {
-                    let prelude_def_map = db.crate_def_map(prelude.krate());
-                    prelude_def_map[prelude.id.module_id].scope.entries().for_each(
-                        |(name, res)| {
-                            f(name.clone(), res.def.into());
-                        },
-                    );
+                    let prelude_def_map = db.crate_def_map(prelude.krate);
+                    prelude_def_map[prelude.module_id].scope.entries().for_each(|(name, res)| {
+                        f(name.clone(), res.def.into());
+                    });
                 }
             }
             Scope::GenericParams(gp) => {
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index a4ca59bba..66cb4b357 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -253,8 +253,11 @@ impl SourceAnalyzer {
             Some(res)
         });
 
-        let items =
-            self.resolver.resolve_module_path(db, &path).take_types().map(PathResolution::Def);
+        let items = self
+            .resolver
+            .resolve_module_path(db, &path)
+            .take_types()
+            .map(|it| PathResolution::Def(it.into()));
         types.or(values).or(items).or_else(|| {
             self.resolver.resolve_path_as_macro(db, &path).map(|def| PathResolution::Macro(def))
         })
diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
index fed52df39..a09ef5c5d 100644
--- a/crates/ra_hir/src/ty/infer/expr.rs
+++ b/crates/ra_hir/src/ty/infer/expr.rs
@@ -11,12 +11,11 @@ use crate::{
     db::HirDatabase,
     expr::{self, Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
     generics::{GenericParams, HasGenericParams},
-    nameres::Namespace,
     ty::{
         autoderef, method_resolution, op, primitive, CallableDef, InferTy, Mutability, Obligation,
         ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
     },
-    Adt, Name,
+    Adt, Name, Namespace,
 };
 
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 8e2834307..e29ab8492 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -23,15 +23,14 @@ use crate::{
     db::HirDatabase,
     generics::HasGenericParams,
     generics::{GenericDef, WherePredicate},
-    nameres::Namespace,
     resolve::{Resolver, TypeNs},
     ty::{
         primitive::{FloatTy, IntTy},
         Adt,
     },
     util::make_mut_slice,
-    Const, Enum, EnumVariant, Function, ModuleDef, Path, Static, Struct, StructField, Trait,
-    TypeAlias, Union,
+    Const, Enum, EnumVariant, Function, ModuleDef, Namespace, Path, Static, Struct, StructField,
+    Trait, TypeAlias, Union,
 };
 
 impl Ty {
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index bfef48b16..4b7e34878 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -2,8 +2,7 @@ use std::fmt::Write;
 use std::sync::Arc;
 
 use insta::assert_snapshot;
-
-use ra_db::{salsa::Database, FilePosition, SourceDatabase};
+use ra_db::{fixture::WithFixture, salsa::Database, FilePosition, SourceDatabase};
 use ra_syntax::{
     algo,
     ast::{self, AstNode},
@@ -25,9 +24,9 @@ mod coercion;
 
 #[test]
 fn cfg_impl_block() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:foo cfg:test
 use foo::S as T;
 struct S;
 
@@ -46,7 +45,7 @@ fn test() {
     t<|>;
 }
 
-//- /foo.rs
+//- /foo.rs crate:foo
 struct S;
 
 #[cfg(not(test))]
@@ -60,18 +59,14 @@ impl S {
 }
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["foo"], cfg = { "test" }),
-        "foo": ("/foo.rs", []),
-    });
     assert_eq!("(i32, {unknown}, i32, {unknown})", type_at_pos(&db, pos));
 }
 
 #[test]
 fn infer_await() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:std
 
 struct IntFuture;
 
@@ -85,7 +80,7 @@ fn test() {
     v<|>;
 }
 
-//- /std.rs
+//- /std.rs crate:std
 #[prelude_import] use future::*;
 mod future {
     trait Future {
@@ -95,18 +90,14 @@ mod future {
 
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["std"]),
-        "std": ("/std.rs", []),
-    });
     assert_eq!("u64", type_at_pos(&db, pos));
 }
 
 #[test]
 fn infer_box() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:std
 
 fn test() {
     let x = box 1;
@@ -114,7 +105,7 @@ fn test() {
     t<|>;
 }
 
-//- /std.rs
+//- /std.rs crate:std
 #[prelude_import] use prelude::*;
 mod prelude {}
 
@@ -126,10 +117,6 @@ mod boxed {
 
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["std"]),
-        "std": ("/std.rs", []),
-    });
     assert_eq!("(Box<i32>, Box<Box<i32>>, Box<&i32>, Box<[i32;_]>)", type_at_pos(&db, pos));
 }
 
@@ -154,9 +141,9 @@ fn test() {
 
 #[test]
 fn infer_try() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:std
 
 fn test() {
     let r: Result<i32, u64> = Result::Ok(1);
@@ -164,7 +151,7 @@ fn test() {
     v<|>;
 }
 
-//- /std.rs
+//- /std.rs crate:std
 
 #[prelude_import] use ops::*;
 mod ops {
@@ -189,18 +176,14 @@ mod result {
 
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["std"]),
-        "std": ("/std.rs", []),
-    });
     assert_eq!("i32", type_at_pos(&db, pos));
 }
 
 #[test]
 fn infer_for_loop() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:std
 
 use std::collections::Vec;
 
@@ -212,7 +195,7 @@ fn test() {
     }
 }
 
-//- /std.rs
+//- /std.rs crate:std
 
 #[prelude_import] use iter::*;
 mod iter {
@@ -234,10 +217,6 @@ mod collections {
 }
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["std"]),
-        "std": ("/std.rs", []),
-    });
     assert_eq!("&str", type_at_pos(&db, pos));
 }
 
@@ -2505,15 +2484,15 @@ pub fn main_loop() {
 
 #[test]
 fn cross_crate_associated_method_call() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:other_crate
 fn test() {
     let x = other_crate::foo::S::thing();
     x<|>;
 }
 
-//- /lib.rs
+//- /lib.rs crate:other_crate
 mod foo {
     struct S;
     impl S {
@@ -2522,10 +2501,6 @@ mod foo {
 }
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["other_crate"]),
-        "other_crate": ("/lib.rs", []),
-    });
     assert_eq!("i128", type_at_pos(&db, pos));
 }
 
@@ -3403,16 +3378,15 @@ fn test() { S.foo()<|>; }
 
 #[test]
 fn infer_macro_with_dollar_crate_is_correct_in_expr() {
-    covers!(macro_dollar_crate_other);
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:foo
 fn test() {
     let x = (foo::foo!(1), foo::foo!(2));
     x<|>;
 }
 
-//- /lib.rs
+//- /lib.rs crate:foo
 #[macro_export]
 macro_rules! foo {
     (1) => { $crate::bar!() };
@@ -3427,10 +3401,6 @@ macro_rules! bar {
 pub fn baz() -> usize { 31usize }
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["foo"]),
-        "foo": ("/lib.rs", []),
-    });
     assert_eq!("(i32, usize)", type_at_pos(&db, pos));
 }
 
@@ -3512,9 +3482,9 @@ fn test() { (&S).foo()<|>; }
 
 #[test]
 fn method_resolution_trait_from_prelude() {
-    let (mut db, pos) = MockDatabase::with_position(
+    let (db, pos) = MockDatabase::with_position(
         r#"
-//- /main.rs
+//- /main.rs crate:main deps:other_crate
 struct S;
 impl Clone for S {}
 
@@ -3522,7 +3492,7 @@ fn test() {
     S.clone()<|>;
 }
 
-//- /lib.rs
+//- /lib.rs crate:other_crate
 #[prelude_import] use foo::*;
 
 mod foo {
@@ -3532,10 +3502,6 @@ mod foo {
 }
 "#,
     );
-    db.set_crate_graph_from_fixture(crate_graph! {
-        "main": ("/main.rs", ["other_crate"]),
-        "other_crate": ("/lib.rs", []),
-    });
     assert_eq!("S", type_at_pos(&db, pos));
 }
 
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index 746c907e8..21262be79 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -7,7 +7,6 @@ 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" }
@@ -19,3 +18,6 @@ test_utils = { path = "../test_utils" }
 mbe = { path = "../ra_mbe", package = "ra_mbe" }
 ra_cfg = { path = "../ra_cfg" }
 tt = { path = "../ra_tt", package = "ra_tt" }
+
+[dev-dependencies]
+insta = "0.12.0"
diff --git a/crates/ra_hir_def/src/adt.rs b/crates/ra_hir_def/src/adt.rs
index 22bd469f0..8f41e55d2 100644
--- a/crates/ra_hir_def/src/adt.rs
+++ b/crates/ra_hir_def/src/adt.rs
@@ -8,7 +8,7 @@ use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
 
 use crate::{
     db::DefDatabase2, type_ref::TypeRef, AstItemDef, EnumId, LocalEnumVariantId,
-    LocalStructFieldId, StructId,
+    LocalStructFieldId, StructId, UnionId,
 };
 
 /// Note that we use `StructData` for unions as well!
@@ -56,6 +56,13 @@ impl StructData {
         let variant_data = Arc::new(variant_data);
         Arc::new(StructData { name, variant_data })
     }
+    pub(crate) fn union_data_query(db: &impl DefDatabase2, struct_: UnionId) -> Arc<StructData> {
+        let src = struct_.source(db);
+        let name = src.ast.name().map(|n| n.as_name());
+        let variant_data = VariantData::new(src.ast.kind());
+        let variant_data = Arc::new(variant_data);
+        Arc::new(StructData { name, variant_data })
+    }
 }
 
 impl EnumData {
@@ -74,6 +81,11 @@ impl EnumData {
             .collect();
         Arc::new(EnumData { name, variants })
     }
+
+    pub(crate) fn variant(&self, name: &Name) -> Option<LocalEnumVariantId> {
+        let (id, _) = self.variants.iter().find(|(_id, data)| data.name.as_ref() == Some(name))?;
+        Some(id)
+    }
 }
 
 impl VariantData {
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index f6027013f..a42348101 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -2,13 +2,16 @@
 use std::sync::Arc;
 
 use hir_expand::{db::AstDatabase, HirFileId};
-use ra_db::{salsa, SourceDatabase};
+use ra_db::{salsa, CrateId, SourceDatabase};
 use ra_syntax::ast;
 
 use crate::{
     adt::{EnumData, StructData},
-    nameres::raw::{ImportSourceMap, RawItems},
-    EnumId, StructId,
+    nameres::{
+        raw::{ImportSourceMap, RawItems},
+        CrateDefMap,
+    },
+    EnumId, StructId, UnionId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -42,9 +45,15 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
     #[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: CrateId) -> Arc<CrateDefMap>;
+
     #[salsa::invoke(StructData::struct_data_query)]
     fn struct_data(&self, s: StructId) -> Arc<StructData>;
 
+    #[salsa::invoke(StructData::union_data_query)]
+    fn union_data(&self, s: UnionId) -> Arc<StructData>;
+
     #[salsa::invoke(EnumData::enum_data_query)]
     fn enum_data(&self, e: EnumId) -> Arc<EnumData>;
 }
diff --git a/crates/ra_hir_def/src/diagnostics.rs b/crates/ra_hir_def/src/diagnostics.rs
new file mode 100644
index 000000000..9843009a5
--- /dev/null
+++ b/crates/ra_hir_def/src/diagnostics.rs
@@ -0,0 +1,28 @@
+//! Diagnostics produced by `hir_def`.
+
+use std::any::Any;
+
+use hir_expand::diagnostics::Diagnostic;
+use ra_db::RelativePathBuf;
+use ra_syntax::{ast, AstPtr, SyntaxNodePtr};
+
+use hir_expand::{HirFileId, Source};
+
+#[derive(Debug)]
+pub struct UnresolvedModule {
+    pub file: HirFileId,
+    pub decl: AstPtr<ast::Module>,
+    pub candidate: RelativePathBuf,
+}
+
+impl Diagnostic for UnresolvedModule {
+    fn message(&self) -> String {
+        "unresolved module".to_string()
+    }
+    fn source(&self) -> Source<SyntaxNodePtr> {
+        Source { file_id: self.file, ast: self.decl.into() }
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index 6d66f481d..63ed2a098 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -13,6 +13,12 @@ pub mod path;
 pub mod type_ref;
 pub mod builtin_type;
 pub mod adt;
+pub mod diagnostics;
+
+#[cfg(test)]
+mod test_db;
+#[cfg(test)]
+mod marks;
 
 // FIXME: this should be private
 pub mod nameres;
@@ -237,8 +243,8 @@ impl AstItemDef<ast::EnumDef> for EnumId {
 // FIXME: rename to `VariantId`, only enums can ave variants
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct EnumVariantId {
-    parent: EnumId,
-    local_id: LocalEnumVariantId,
+    pub parent: EnumId,
+    pub local_id: LocalEnumVariantId,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
diff --git a/crates/ra_hir_def/src/marks.rs b/crates/ra_hir_def/src/marks.rs
new file mode 100644
index 000000000..0b99eac71
--- /dev/null
+++ b/crates/ra_hir_def/src/marks.rs
@@ -0,0 +1,14 @@
+//! See test_utils/src/marks.rs
+
+test_utils::marks!(
+    bogus_paths
+    name_res_works_for_broken_modules
+    can_import_enum_variant
+    glob_enum
+    glob_across_crates
+    std_prelude
+    macro_rules_from_other_crates_are_visible_with_macro_use
+    prelude_is_macro_use
+    macro_dollar_crate_self
+    macro_dollar_crate_other
+);
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 11ba8a777..433bdde48 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -1,5 +1,543 @@
-//! FIXME: write short doc here
+//! This module implements import-resolution/macro expansion algorithm.
+//!
+//! The result of this module is `CrateDefMap`: a data structure which contains:
+//!
+//!   * a tree of modules for the crate
+//!   * for each module, a set of items visible in the module (directly declared
+//!     or imported)
+//!
+//! Note that `CrateDefMap` contains fully macro expanded code.
+//!
+//! Computing `CrateDefMap` can be partitioned into several logically
+//! independent "phases". The phases are mutually recursive though, there's no
+//! strict ordering.
+//!
+//! ## Collecting RawItems
+//!
+//!  This happens in the `raw` module, which parses a single source file into a
+//!  set of top-level items. Nested imports are desugared to flat imports in
+//!  this phase. Macro calls are represented as a triple of (Path, Option<Name>,
+//!  TokenTree).
+//!
+//! ## Collecting Modules
+//!
+//! This happens in the `collector` module. In this phase, we recursively walk
+//! tree of modules, collect raw items from submodules, populate module scopes
+//! with defined items (so, we assign item ids in this phase) and record the set
+//! of unresolved imports and macros.
+//!
+//! While we walk tree of modules, we also record macro_rules definitions and
+//! expand calls to macro_rules defined macros.
+//!
+//! ## Resolving Imports
+//!
+//! We maintain a list of currently unresolved imports. On every iteration, we
+//! try to resolve some imports from this list. If the import is resolved, we
+//! record it, by adding an item to current module scope and, if necessary, by
+//! recursively populating glob imports.
+//!
+//! ## Resolving Macros
+//!
+//! macro_rules from the same crate use a global mutable namespace. We expand
+//! them immediately, when we collect modules.
+//!
+//! Macros from other crates (including proc-macros) can be used with
+//! `foo::bar!` syntax. We handle them similarly to imports. There's a list of
+//! unexpanded macros. On every iteration, we try to resolve each macro call
+//! path and, upon success, we run macro expansion and "collect module" phase
+//! on the result
 
 // FIXME: review privacy of submodules
 pub mod raw;
+pub mod per_ns;
+pub mod collector;
 pub mod mod_resolution;
+
+#[cfg(test)]
+mod tests;
+
+use std::sync::Arc;
+
+use hir_expand::{diagnostics::DiagnosticSink, name::Name, MacroDefId};
+use once_cell::sync::Lazy;
+use ra_arena::Arena;
+use ra_db::{CrateId, Edition, FileId};
+use ra_prof::profile;
+use ra_syntax::ast;
+use rustc_hash::{FxHashMap, FxHashSet};
+use test_utils::tested_by;
+
+use crate::{
+    builtin_type::BuiltinType,
+    db::DefDatabase2,
+    nameres::{diagnostics::DefDiagnostic, per_ns::PerNs, raw::ImportId},
+    path::{Path, PathKind},
+    AdtId, AstId, CrateModuleId, EnumVariantId, ModuleDefId, ModuleId, TraitId,
+};
+
+/// Contains all top-level defs from a macro-expanded crate
+#[derive(Debug, PartialEq, Eq)]
+pub struct CrateDefMap {
+    krate: CrateId,
+    edition: Edition,
+    /// The prelude module for this crate. This either comes from an import
+    /// marked with the `prelude_import` attribute, or (in the normal case) from
+    /// a dependency (`std` or `core`).
+    prelude: Option<ModuleId>,
+    extern_prelude: FxHashMap<Name, ModuleDefId>,
+    root: CrateModuleId,
+    pub modules: Arena<CrateModuleId, ModuleData>,
+
+    /// Some macros are not well-behavior, which leads to infinite loop
+    /// e.g. macro_rules! foo { ($ty:ty) => { foo!($ty); } }
+    /// We mark it down and skip it in collector
+    ///
+    /// FIXME:
+    /// Right now it only handle a poison macro in a single crate,
+    /// such that if other crate try to call that macro,
+    /// the whole process will do again until it became poisoned in that crate.
+    /// We should handle this macro set globally
+    /// However, do we want to put it as a global variable?
+    poison_macros: FxHashSet<MacroDefId>,
+
+    diagnostics: Vec<DefDiagnostic>,
+}
+
+impl std::ops::Index<CrateModuleId> for CrateDefMap {
+    type Output = ModuleData;
+    fn index(&self, id: CrateModuleId) -> &ModuleData {
+        &self.modules[id]
+    }
+}
+
+#[derive(Default, Debug, PartialEq, Eq)]
+pub struct ModuleData {
+    pub parent: Option<CrateModuleId>,
+    pub children: FxHashMap<Name, CrateModuleId>,
+    pub scope: ModuleScope,
+    /// None for root
+    pub declaration: Option<AstId<ast::Module>>,
+    /// None for inline modules.
+    ///
+    /// Note that non-inline modules, by definition, live inside non-macro file.
+    pub definition: Option<FileId>,
+}
+
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
+pub struct ModuleScope {
+    pub items: FxHashMap<Name, Resolution>,
+    /// Macros visable in current module in legacy textual scope
+    ///
+    /// For macros invoked by an unquatified identifier like `bar!()`, `legacy_macros` will be searched in first.
+    /// If it yields no result, then it turns to module scoped `macros`.
+    /// It macros with name quatified with a path like `crate::foo::bar!()`, `legacy_macros` will be skipped,
+    /// and only normal scoped `macros` will be searched in.
+    ///
+    /// Note that this automatically inherit macros defined textually before the definition of module itself.
+    ///
+    /// Module scoped macros will be inserted into `items` instead of here.
+    // FIXME: Macro shadowing in one module is not properly handled. Non-item place macros will
+    // be all resolved to the last one defined if shadowing happens.
+    legacy_macros: FxHashMap<Name, MacroDefId>,
+}
+
+static BUILTIN_SCOPE: Lazy<FxHashMap<Name, Resolution>> = Lazy::new(|| {
+    BuiltinType::ALL
+        .iter()
+        .map(|(name, ty)| {
+            (name.clone(), Resolution { def: PerNs::types(ty.clone().into()), import: None })
+        })
+        .collect()
+});
+
+/// Legacy macros can only be accessed through special methods like `get_legacy_macros`.
+/// Other methods will only resolve values, types and module scoped macros only.
+impl ModuleScope {
+    pub fn entries<'a>(&'a self) -> impl Iterator<Item = (&'a Name, &'a Resolution)> + 'a {
+        //FIXME: shadowing
+        self.items.iter().chain(BUILTIN_SCOPE.iter())
+    }
+
+    /// Iterate over all module scoped macros
+    pub fn macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDefId)> + 'a {
+        self.items
+            .iter()
+            .filter_map(|(name, res)| res.def.get_macros().map(|macro_| (name, macro_)))
+    }
+
+    /// Iterate over all legacy textual scoped macros visable at the end of the module
+    pub fn legacy_macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDefId)> + 'a {
+        self.legacy_macros.iter().map(|(name, def)| (name, *def))
+    }
+
+    /// Get a name from current module scope, legacy macros are not included
+    pub fn get(&self, name: &Name) -> Option<&Resolution> {
+        self.items.get(name).or_else(|| BUILTIN_SCOPE.get(name))
+    }
+
+    pub fn traits<'a>(&'a self) -> impl Iterator<Item = TraitId> + 'a {
+        self.items.values().filter_map(|r| match r.def.take_types() {
+            Some(ModuleDefId::TraitId(t)) => Some(t),
+            _ => None,
+        })
+    }
+
+    fn get_legacy_macro(&self, name: &Name) -> Option<MacroDefId> {
+        self.legacy_macros.get(name).copied()
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct Resolution {
+    /// None for unresolved
+    pub def: PerNs,
+    /// ident by which this is imported into local scope.
+    pub import: Option<ImportId>,
+}
+
+impl Resolution {
+    pub(crate) fn from_macro(macro_: MacroDefId) -> Self {
+        Resolution { def: PerNs::macros(macro_), import: None }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct ResolvePathResult {
+    resolved_def: PerNs,
+    segment_index: Option<usize>,
+    reached_fixedpoint: ReachedFixedPoint,
+}
+
+impl ResolvePathResult {
+    fn empty(reached_fixedpoint: ReachedFixedPoint) -> ResolvePathResult {
+        ResolvePathResult::with(PerNs::none(), reached_fixedpoint, None)
+    }
+
+    fn with(
+        resolved_def: PerNs,
+        reached_fixedpoint: ReachedFixedPoint,
+        segment_index: Option<usize>,
+    ) -> ResolvePathResult {
+        ResolvePathResult { resolved_def, reached_fixedpoint, segment_index }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum ResolveMode {
+    Import,
+    Other,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum ReachedFixedPoint {
+    Yes,
+    No,
+}
+
+impl CrateDefMap {
+    pub(crate) fn crate_def_map_query(
+        // Note that this doesn't have `+ AstDatabase`!
+        // This gurantess that `CrateDefMap` is stable across reparses.
+        db: &impl DefDatabase2,
+        krate: CrateId,
+    ) -> Arc<CrateDefMap> {
+        let _p = profile("crate_def_map_query");
+        let def_map = {
+            let crate_graph = db.crate_graph();
+            let edition = crate_graph.edition(krate);
+            let mut modules: Arena<CrateModuleId, ModuleData> = Arena::default();
+            let root = modules.alloc(ModuleData::default());
+            CrateDefMap {
+                krate,
+                edition,
+                extern_prelude: FxHashMap::default(),
+                prelude: None,
+                root,
+                modules,
+                poison_macros: FxHashSet::default(),
+                diagnostics: Vec::new(),
+            }
+        };
+        let def_map = collector::collect_defs(db, def_map);
+        Arc::new(def_map)
+    }
+
+    pub fn krate(&self) -> CrateId {
+        self.krate
+    }
+
+    pub fn root(&self) -> CrateModuleId {
+        self.root
+    }
+
+    pub fn prelude(&self) -> Option<ModuleId> {
+        self.prelude
+    }
+
+    pub fn extern_prelude(&self) -> &FxHashMap<Name, ModuleDefId> {
+        &self.extern_prelude
+    }
+
+    pub fn add_diagnostics(
+        &self,
+        db: &impl DefDatabase2,
+        module: CrateModuleId,
+        sink: &mut DiagnosticSink,
+    ) {
+        self.diagnostics.iter().for_each(|it| it.add_to(db, module, sink))
+    }
+
+    pub fn resolve_path(
+        &self,
+        db: &impl DefDatabase2,
+        original_module: CrateModuleId,
+        path: &Path,
+    ) -> (PerNs, Option<usize>) {
+        let res = self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path);
+        (res.resolved_def, res.segment_index)
+    }
+
+    // Returns Yes if we are sure that additions to `ItemMap` wouldn't change
+    // the result.
+    fn resolve_path_fp_with_macro(
+        &self,
+        db: &impl DefDatabase2,
+        mode: ResolveMode,
+        original_module: CrateModuleId,
+        path: &Path,
+    ) -> ResolvePathResult {
+        let mut segments = path.segments.iter().enumerate();
+        let mut curr_per_ns: PerNs = match path.kind {
+            PathKind::DollarCrate(krate) => {
+                if krate == self.krate {
+                    tested_by!(macro_dollar_crate_self);
+                    PerNs::types(ModuleId { krate: self.krate, module_id: self.root }.into())
+                } else {
+                    let def_map = db.crate_def_map(krate);
+                    let module = ModuleId { krate, module_id: def_map.root };
+                    tested_by!(macro_dollar_crate_other);
+                    PerNs::types(module.into())
+                }
+            }
+            PathKind::Crate => {
+                PerNs::types(ModuleId { krate: self.krate, module_id: self.root }.into())
+            }
+            PathKind::Self_ => {
+                PerNs::types(ModuleId { 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)
+            // FIXME there must be a nicer way to write this condition
+            PathKind::Plain | PathKind::Abs
+                if self.edition == Edition::Edition2015
+                    && (path.kind == PathKind::Abs || mode == ResolveMode::Import) =>
+            {
+                let segment = match segments.next() {
+                    Some((_, segment)) => segment,
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                log::debug!("resolving {:?} in crate root (+ extern prelude)", segment);
+                self.resolve_name_in_crate_root_or_extern_prelude(&segment.name)
+            }
+            PathKind::Plain => {
+                let segment = match segments.next() {
+                    Some((_, segment)) => segment,
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                log::debug!("resolving {:?} in module", segment);
+                self.resolve_name_in_module(db, original_module, &segment.name)
+            }
+            PathKind::Super => {
+                if let Some(p) = self.modules[original_module].parent {
+                    PerNs::types(ModuleId { krate: self.krate, module_id: p }.into())
+                } else {
+                    log::debug!("super path in root module");
+                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                }
+            }
+            PathKind::Abs => {
+                // 2018-style absolute path -- only extern prelude
+                let segment = match segments.next() {
+                    Some((_, segment)) => segment,
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                if let Some(def) = self.extern_prelude.get(&segment.name) {
+                    log::debug!("absolute path {:?} resolved to crate {:?}", path, def);
+                    PerNs::types(*def)
+                } else {
+                    return ResolvePathResult::empty(ReachedFixedPoint::No); // extern crate declarations can add to the extern prelude
+                }
+            }
+            PathKind::Type(_) => {
+                // This is handled in `infer::infer_path_expr`
+                // The result returned here does not matter
+                return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+            }
+        };
+
+        for (i, segment) in segments {
+            let curr = match curr_per_ns.take_types() {
+                Some(r) => r,
+                None => {
+                    // we still have path segments left, but the path so far
+                    // didn't resolve in the types namespace => no resolution
+                    // (don't break here because `curr_per_ns` might contain
+                    // something in the value namespace, and it would be wrong
+                    // to return that)
+                    return ResolvePathResult::empty(ReachedFixedPoint::No);
+                }
+            };
+            // resolve segment in curr
+
+            curr_per_ns = match curr {
+                ModuleDefId::ModuleId(module) => {
+                    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 (def, s) = defp_map.resolve_path(db, module.module_id, &path);
+                        return ResolvePathResult::with(
+                            def,
+                            ReachedFixedPoint::Yes,
+                            s.map(|s| s + i),
+                        );
+                    }
+
+                    // Since it is a qualified path here, it should not contains legacy macros
+                    match self[module.module_id].scope.get(&segment.name) {
+                        Some(res) => res.def,
+                        _ => {
+                            log::debug!("path segment {:?} not found", segment.name);
+                            return ResolvePathResult::empty(ReachedFixedPoint::No);
+                        }
+                    }
+                }
+                ModuleDefId::AdtId(AdtId::EnumId(e)) => {
+                    // enum variant
+                    tested_by!(can_import_enum_variant);
+                    let enum_data = db.enum_data(e);
+                    match enum_data.variant(&segment.name) {
+                        Some(local_id) => {
+                            let variant = EnumVariantId { parent: e, local_id };
+                            PerNs::both(variant.into(), variant.into())
+                        }
+                        None => {
+                            return ResolvePathResult::with(
+                                PerNs::types(e.into()),
+                                ReachedFixedPoint::Yes,
+                                Some(i),
+                            );
+                        }
+                    }
+                }
+                s => {
+                    // could be an inherent method call in UFCS form
+                    // (`Struct::method`), or some other kind of associated item
+                    log::debug!(
+                        "path segment {:?} resolved to non-module {:?}, but is not last",
+                        segment.name,
+                        curr,
+                    );
+
+                    return ResolvePathResult::with(
+                        PerNs::types(s),
+                        ReachedFixedPoint::Yes,
+                        Some(i),
+                    );
+                }
+            };
+        }
+        ResolvePathResult::with(curr_per_ns, ReachedFixedPoint::Yes, None)
+    }
+
+    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> PerNs {
+        let from_crate_root =
+            self[self.root].scope.get(name).map_or_else(PerNs::none, |res| res.def);
+        let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
+
+        from_crate_root.or(from_extern_prelude)
+    }
+
+    pub(crate) fn resolve_name_in_module(
+        &self,
+        db: &impl DefDatabase2,
+        module: CrateModuleId,
+        name: &Name,
+    ) -> PerNs {
+        // Resolve in:
+        //  - legacy scope of macro
+        //  - current module / scope
+        //  - extern prelude
+        //  - std prelude
+        let from_legacy_macro =
+            self[module].scope.get_legacy_macro(name).map_or_else(PerNs::none, PerNs::macros);
+        let from_scope = self[module].scope.get(name).map_or_else(PerNs::none, |res| res.def);
+        let from_extern_prelude =
+            self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it));
+        let from_prelude = self.resolve_in_prelude(db, name);
+
+        from_legacy_macro.or(from_scope).or(from_extern_prelude).or(from_prelude)
+    }
+
+    fn resolve_name_in_extern_prelude(&self, name: &Name) -> PerNs {
+        self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it))
+    }
+
+    fn resolve_in_prelude(&self, db: &impl DefDatabase2, name: &Name) -> PerNs {
+        if let Some(prelude) = self.prelude {
+            let keep;
+            let def_map = if prelude.krate == self.krate {
+                self
+            } else {
+                // Extend lifetime
+                keep = db.crate_def_map(prelude.krate);
+                &keep
+            };
+            def_map[prelude.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
+        } else {
+            PerNs::none()
+        }
+    }
+}
+
+mod diagnostics {
+    use hir_expand::diagnostics::DiagnosticSink;
+    use ra_db::RelativePathBuf;
+    use ra_syntax::{ast, AstPtr};
+
+    use crate::{db::DefDatabase2, diagnostics::UnresolvedModule, nameres::CrateModuleId, AstId};
+
+    #[derive(Debug, PartialEq, Eq)]
+    pub(super) enum DefDiagnostic {
+        UnresolvedModule {
+            module: CrateModuleId,
+            declaration: AstId<ast::Module>,
+            candidate: RelativePathBuf,
+        },
+    }
+
+    impl DefDiagnostic {
+        pub(super) fn add_to(
+            &self,
+            db: &impl DefDatabase2,
+            target_module: CrateModuleId,
+            sink: &mut DiagnosticSink,
+        ) {
+            match self {
+                DefDiagnostic::UnresolvedModule { module, declaration, candidate } => {
+                    if *module != target_module {
+                        return;
+                    }
+                    let decl = declaration.to_node(db);
+                    sink.push(UnresolvedModule {
+                        file: declaration.file_id(),
+                        decl: AstPtr::new(&decl),
+                        candidate: candidate.clone(),
+                    })
+                }
+            }
+        }
+    }
+}
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index ee0a4c99f..3b61d9895 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -1,45 +1,49 @@
 //! FIXME: write short doc here
 
-use hir_def::{
-    attr::Attr,
-    nameres::{mod_resolution::ModDir, raw},
+use hir_expand::{
+    name::{self, AsName, Name},
+    HirFileId, MacroCallId, MacroCallLoc, MacroDefId, MacroFileKind,
 };
-use hir_expand::name;
 use ra_cfg::CfgOptions;
-use ra_db::FileId;
+use ra_db::{CrateId, FileId};
 use ra_syntax::{ast, SmolStr};
 use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 
 use crate::{
-    db::DefDatabase,
-    ids::{AstItemDef, LocationCtx, MacroCallId, MacroCallLoc, MacroDefId, MacroFileKind},
+    attr::Attr,
+    db::DefDatabase2,
     nameres::{
-        diagnostics::DefDiagnostic, Crate, CrateDefMap, CrateModuleId, ModuleData, ModuleDef,
-        PerNs, ReachedFixedPoint, Resolution, ResolveMode,
+        diagnostics::DefDiagnostic, mod_resolution::ModDir, per_ns::PerNs, raw, CrateDefMap,
+        ModuleData, ReachedFixedPoint, Resolution, ResolveMode,
     },
-    Adt, AstId, Const, Enum, Function, HirFileId, MacroDef, Module, Name, Path, PathKind, Static,
-    Struct, Trait, TypeAlias, Union,
+    path::{Path, PathKind},
+    AdtId, AstId, AstItemDef, ConstId, CrateModuleId, EnumId, EnumVariantId, FunctionId,
+    LocationCtx, ModuleDefId, ModuleId, StaticId, StructId, TraitId, TypeAliasId, UnionId,
 };
 
-pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> CrateDefMap {
+pub(super) fn collect_defs(db: &impl DefDatabase2, mut def_map: CrateDefMap) -> CrateDefMap {
+    let crate_graph = db.crate_graph();
+
     // populate external prelude
-    for dep in def_map.krate.dependencies(db) {
-        log::debug!("crate dep {:?} -> {:?}", dep.name, dep.krate);
-        if let Some(module) = dep.krate.root_module(db) {
-            def_map.extern_prelude.insert(dep.name.clone(), module.into());
-        }
+    for dep in crate_graph.dependencies(def_map.krate) {
+        let dep_def_map = db.crate_def_map(dep.crate_id);
+        log::debug!("crate dep {:?} -> {:?}", dep.name, dep.crate_id);
+        def_map.extern_prelude.insert(
+            dep.as_name(),
+            ModuleId { krate: dep.crate_id, module_id: dep_def_map.root }.into(),
+        );
+
         // look for the prelude
         if def_map.prelude.is_none() {
-            let map = db.crate_def_map(dep.krate);
+            let map = db.crate_def_map(dep.crate_id);
             if map.prelude.is_some() {
                 def_map.prelude = map.prelude;
             }
         }
     }
 
-    let crate_graph = db.crate_graph();
-    let cfg_options = crate_graph.cfg_options(def_map.krate().crate_id());
+    let cfg_options = crate_graph.cfg_options(def_map.krate);
 
     let mut collector = DefCollector {
         db,
@@ -101,11 +105,11 @@ struct DefCollector<'a, DB> {
 
 impl<DB> DefCollector<'_, DB>
 where
-    DB: DefDatabase,
+    DB: DefDatabase2,
 {
     fn collect(&mut self) {
         let crate_graph = self.db.crate_graph();
-        let file_id = crate_graph.crate_root(self.def_map.krate.crate_id());
+        let file_id = crate_graph.crate_root(self.def_map.krate);
         let raw_items = self.db.raw_items(file_id.into());
         let module_id = self.def_map.root;
         self.def_map.modules[module_id].definition = Some(file_id);
@@ -168,7 +172,7 @@ where
         &mut self,
         module_id: CrateModuleId,
         name: Name,
-        macro_: MacroDef,
+        macro_: MacroDefId,
         export: bool,
     ) {
         // Textual scoping
@@ -189,7 +193,7 @@ where
     /// the definition of current module.
     /// And also, `macro_use` on a module will import all legacy macros visable inside to
     /// current legacy scope, with possible shadowing.
-    fn define_legacy_macro(&mut self, module_id: CrateModuleId, name: Name, macro_: MacroDef) {
+    fn define_legacy_macro(&mut self, module_id: CrateModuleId, name: Name, macro_: MacroDefId) {
         // Always shadowing
         self.def_map.modules[module_id].scope.legacy_macros.insert(name, macro_);
     }
@@ -213,9 +217,9 @@ where
                 .expect("extern crate should have been desugared to one-element path"),
         );
 
-        if let Some(ModuleDef::Module(m)) = res.take_types() {
+        if let Some(ModuleDefId::ModuleId(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);
         }
     }
 
@@ -224,7 +228,7 @@ where
     /// Exported macros are just all macros in the root module scope.
     /// Note that it contains not only all `#[macro_export]` macros, but also all aliases
     /// created by `use` in the root module, ignoring the visibility of `use`.
-    fn import_all_macros_exported(&mut self, current_module_id: CrateModuleId, krate: Crate) {
+    fn import_all_macros_exported(&mut self, current_module_id: CrateModuleId, krate: CrateId) {
         let def_map = self.db.crate_def_map(krate);
         for (name, def) in def_map[def_map.root].scope.macros() {
             // `macro_use` only bring things into legacy scope.
@@ -288,15 +292,15 @@ where
         if import.is_glob {
             log::debug!("glob import: {:?}", import);
             match def.take_types() {
-                Some(ModuleDef::Module(m)) => {
+                Some(ModuleDefId::ModuleId(m)) => {
                     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 scope = &item_map[m.id.module_id].scope;
+                        let item_map = self.db.crate_def_map(m.krate);
+                        let scope = &item_map[m.module_id].scope;
 
                         // Module scoped macros is included
                         let items = scope
@@ -310,7 +314,7 @@ 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.id.module_id].scope;
+                        let scope = &self.def_map[m.module_id].scope;
 
                         // Module scoped macros is included
                         let items = scope
@@ -322,23 +326,25 @@ where
                         self.update(module_id, Some(import_id), &items);
                         // record the glob import in case we add further items
                         self.glob_imports
-                            .entry(m.id.module_id)
+                            .entry(m.module_id)
                             .or_default()
                             .push((module_id, import_id));
                     }
                 }
-                Some(ModuleDef::Adt(Adt::Enum(e))) => {
+                Some(ModuleDefId::AdtId(AdtId::EnumId(e))) => {
                     tested_by!(glob_enum);
                     // glob import from enum => just import all the variants
-                    let variants = e.variants(self.db);
-                    let resolutions = variants
-                        .into_iter()
-                        .filter_map(|variant| {
+                    let enum_data = self.db.enum_data(e);
+                    let resolutions = enum_data
+                        .variants
+                        .iter()
+                        .filter_map(|(local_id, variant_data)| {
+                            let name = variant_data.name.clone()?;
+                            let variant = EnumVariantId { parent: e, local_id };
                             let res = Resolution {
                                 def: PerNs::both(variant.into(), variant.into()),
                                 import: Some(import_id),
                             };
-                            let name = variant.name(self.db)?;
                             Some((name, res))
                         })
                         .collect::<Vec<_>>();
@@ -451,8 +457,8 @@ where
             );
 
             if let Some(def) = resolved_res.resolved_def.get_macros() {
-                let call_id = self.db.intern_macro(MacroCallLoc { def: def.id, ast_id: *ast_id });
-                resolved.push((*module_id, call_id, def.id));
+                let call_id = self.db.intern_macro(MacroCallLoc { def, ast_id: *ast_id });
+                resolved.push((*module_id, call_id, def));