Merge remote-tracking branch 'upstream/master' into issue961_profiling

21 files changed, 931 insertions, 502 deletions

diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 45fa4cd11..624c25c4d 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -1,8 +1,7 @@
 use std::sync::Arc;
 
-use relative_path::RelativePathBuf;
 use ra_db::{CrateId, SourceRootId, Edition};
-use ra_syntax::{ast::self, TreeArc, SyntaxNode};
+use ra_syntax::{ast::self, TreeArc};
 
 use crate::{
     Name, ScopesWithSourceMap, Ty, HirFileId,
@@ -14,9 +13,11 @@ use crate::{
     adt::{EnumVariantId, StructFieldId, VariantDef},
     generics::GenericParams,
     docs::{Documentation, Docs, docs_from_ast},
-    ids::{FunctionId, StructId, EnumId, AstItemDef, ConstId, StaticId, TraitId, TypeId},
+    ids::{FunctionId, StructId, EnumId, AstItemDef, ConstId, StaticId, TraitId, TypeAliasId},
     impl_block::ImplBlock,
     resolve::Resolver,
+    diagnostics::DiagnosticSink,
+    traits::{TraitItem, TraitData},
 };
 
 /// hir::Crate describes a single crate. It's the main interface with which
@@ -95,11 +96,6 @@ pub enum ModuleSource {
     Module(TreeArc<ast::Module>),
 }
 
-#[derive(Clone, Debug, Hash, PartialEq, Eq)]
-pub enum Problem {
-    UnresolvedModule { candidate: RelativePathBuf },
-}
-
 impl Module {
     /// Name of this module.
     pub fn name(&self, db: &impl HirDatabase) -> Option<Name> {
@@ -171,8 +167,24 @@ impl Module {
         db.crate_def_map(self.krate)[self.module_id].scope.clone()
     }
 
-    pub fn problems(&self, db: &impl HirDatabase) -> Vec<(TreeArc<SyntaxNode>, Problem)> {
-        self.problems_impl(db)
+    pub fn diagnostics(&self, db: &impl HirDatabase, sink: &mut DiagnosticSink) {
+        db.crate_def_map(self.krate).add_diagnostics(db, self.module_id, sink);
+        for decl in self.declarations(db) {
+            match decl {
+                crate::ModuleDef::Function(f) => f.diagnostics(db, sink),
+                crate::ModuleDef::Module(f) => f.diagnostics(db, sink),
+                _ => (),
+            }
+        }
+
+        for impl_block in self.impl_blocks(db) {
+            for item in impl_block.items(db) {
+                match item {
+                    crate::ImplItem::Method(f) => f.diagnostics(db, sink),
+                    _ => (),
+                }
+            }
+        }
     }
 
     pub fn resolver(&self, db: &impl HirDatabase) -> Resolver {
@@ -519,6 +531,10 @@ impl Function {
         let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
         r
     }
+
+    pub fn diagnostics(&self, db: &impl HirDatabase, sink: &mut DiagnosticSink) {
+        self.infer(db).add_diagnostics(db, *self, sink);
+    }
 }
 
 impl Docs for Function {
@@ -634,6 +650,18 @@ impl Trait {
     pub fn generic_params(&self, db: &impl DefDatabase) -> Arc<GenericParams> {
         db.generic_params((*self).into())
     }
+
+    pub fn name(self, db: &impl DefDatabase) -> Option<Name> {
+        self.trait_data(db).name().clone()
+    }
+
+    pub fn items(self, db: &impl DefDatabase) -> Vec<TraitItem> {
+        self.trait_data(db).items().to_vec()
+    }
+
+    pub(crate) fn trait_data(self, db: &impl DefDatabase) -> Arc<TraitData> {
+        db.trait_data(self)
+    }
 }
 
 impl Docs for Trait {
@@ -644,7 +672,7 @@ impl Docs for Trait {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct TypeAlias {
-    pub(crate) id: TypeId,
+    pub(crate) id: TypeAliasId,
 }
 
 impl TypeAlias {
diff --git a/crates/ra_hir/src/code_model_impl/module.rs b/crates/ra_hir/src/code_model_impl/module.rs
index 52a33e981..0edb8ade5 100644
--- a/crates/ra_hir/src/code_model_impl/module.rs
+++ b/crates/ra_hir/src/code_model_impl/module.rs
@@ -1,18 +1,18 @@
 use ra_db::FileId;
-use ra_syntax::{ast, SyntaxNode, TreeArc, AstNode};
+use ra_syntax::{ast, TreeArc};
 
 use crate::{
-    Module, ModuleSource, Problem, Name,
+    Module, ModuleSource, Name, AstId,
     nameres::{CrateModuleId, ImportId},
     HirDatabase, DefDatabase,
-    HirFileId, SourceItemId,
+    HirFileId,
 };
 
 impl ModuleSource {
     pub(crate) fn new(
         db: &impl DefDatabase,
         file_id: Option<FileId>,
-        decl_id: Option<SourceItemId>,
+        decl_id: Option<AstId<ast::Module>>,
     ) -> ModuleSource {
         match (file_id, decl_id) {
             (Some(file_id), _) => {
@@ -20,8 +20,7 @@ impl ModuleSource {
                 ModuleSource::SourceFile(source_file)
             }
             (None, Some(item_id)) => {
-                let module = db.file_item(item_id);
-                let module = ast::Module::cast(&*module).unwrap();
+                let module = item_id.to_node(db);
                 assert!(module.item_list().is_some(), "expected inline module");
                 ModuleSource::Module(module.to_owned())
             }
@@ -55,7 +54,7 @@ impl Module {
         let decl_id = def_map[self.module_id].declaration;
         let file_id = def_map[self.module_id].definition;
         let module_source = ModuleSource::new(db, file_id, decl_id);
-        let file_id = file_id.map(HirFileId::from).unwrap_or_else(|| decl_id.unwrap().file_id);
+        let file_id = file_id.map(HirFileId::from).unwrap_or_else(|| decl_id.unwrap().file_id());
         (file_id, module_source)
     }
 
@@ -65,9 +64,8 @@ impl Module {
     ) -> Option<(HirFileId, TreeArc<ast::Module>)> {
         let def_map = db.crate_def_map(self.krate);
         let decl = def_map[self.module_id].declaration?;
-        let syntax_node = db.file_item(decl);
-        let ast = ast::Module::cast(&syntax_node).unwrap().to_owned();
-        Some((decl.file_id, ast))
+        let ast = decl.to_node(db);
+        Some((decl.file_id(), ast))
     }
 
     pub(crate) fn import_source_impl(
@@ -76,7 +74,7 @@ impl Module {
         import: ImportId,
     ) -> TreeArc<ast::PathSegment> {
         let (file_id, source) = self.definition_source(db);
-        let (_, source_map) = db.raw_items_with_source_map(file_id.original_file(db));
+        let (_, source_map) = db.raw_items_with_source_map(file_id);
         source_map.get(&source, import)
     }
 
@@ -108,19 +106,4 @@ impl Module {
         let parent_id = def_map[self.module_id].parent?;
         Some(self.with_module_id(parent_id))
     }
-
-    pub(crate) fn problems_impl(
-        &self,
-        db: &impl HirDatabase,
-    ) -> Vec<(TreeArc<SyntaxNode>, Problem)> {
-        let def_map = db.crate_def_map(self.krate);
-        let (my_file_id, _) = self.definition_source(db);
-        // FIXME: not entirely corret filterint by module
-        def_map
-            .problems()
-            .iter()
-            .filter(|(source_item_id, _problem)| my_file_id == source_item_id.file_id)
-            .map(|(source_item_id, problem)| (db.file_item(*source_item_id), problem.clone()))
-            .collect()
-    }
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index d3908f8ac..147005848 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,10 +1,10 @@
 use std::sync::Arc;
 
 use ra_syntax::{SyntaxNode, TreeArc, SourceFile};
-use ra_db::{SourceDatabase, salsa, FileId};
+use ra_db::{SourceDatabase, salsa};
 
 use crate::{
-    HirFileId, SourceFileItems, SourceItemId, Crate, Module, HirInterner,
+    HirFileId, MacroDefId, AstIdMap, ErasedFileAstId, Crate, Module, HirInterner,
     Function, FnSignature, ExprScopes, TypeAlias,
     Struct, Enum, StructField,
     Const, ConstSignature, Static,
@@ -14,11 +14,15 @@ use crate::{
     impl_block::{ModuleImplBlocks, ImplSourceMap},
     generics::{GenericParams, GenericDef},
     type_ref::TypeRef,
+    traits::TraitData, Trait, ty::TraitRef
 };
 
 #[salsa::query_group(DefDatabaseStorage)]
 pub trait DefDatabase: SourceDatabase + AsRef<HirInterner> {
-    #[salsa::invoke(HirFileId::hir_parse)]
+    #[salsa::invoke(crate::ids::macro_def_query)]
+    fn macro_def(&self, macro_id: MacroDefId) -> Option<Arc<mbe::MacroRules>>;
+
+    #[salsa::invoke(HirFileId::hir_parse_query)]
     fn hir_parse(&self, file_id: HirFileId) -> TreeArc<SourceFile>;
 
     #[salsa::invoke(crate::adt::StructData::struct_data_query)]
@@ -27,17 +31,23 @@ pub trait DefDatabase: SourceDatabase + AsRef<HirInterner> {
     #[salsa::invoke(crate::adt::EnumData::enum_data_query)]
     fn enum_data(&self, e: Enum) -> Arc<EnumData>;
 
-    #[salsa::invoke(crate::ids::SourceFileItems::file_items_query)]
-    fn file_items(&self, file_id: HirFileId) -> Arc<SourceFileItems>;
+    #[salsa::invoke(crate::traits::TraitData::trait_data_query)]
+    fn trait_data(&self, t: Trait) -> Arc<TraitData>;
+
+    #[salsa::invoke(crate::source_id::AstIdMap::ast_id_map_query)]
+    fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;
 
-    #[salsa::invoke(crate::ids::SourceFileItems::file_item_query)]
-    fn file_item(&self, source_item_id: SourceItemId) -> TreeArc<SyntaxNode>;
+    #[salsa::invoke(crate::source_id::AstIdMap::file_item_query)]
+    fn ast_id_to_node(&self, file_id: HirFileId, ast_id: ErasedFileAstId) -> TreeArc<SyntaxNode>;
 
     #[salsa::invoke(RawItems::raw_items_query)]
-    fn raw_items(&self, file_id: FileId) -> Arc<RawItems>;
+    fn raw_items(&self, file_id: HirFileId) -> Arc<RawItems>;
 
     #[salsa::invoke(RawItems::raw_items_with_source_map_query)]
-    fn raw_items_with_source_map(&self, file_id: FileId) -> (Arc<RawItems>, Arc<ImportSourceMap>);
+    fn raw_items_with_source_map(
+        &self,
+        file_id: HirFileId,
+    ) -> (Arc<RawItems>, Arc<ImportSourceMap>);
 
     #[salsa::invoke(CrateDefMap::crate_def_map_query)]
     fn crate_def_map(&self, krate: Crate) -> Arc<CrateDefMap>;
@@ -98,6 +108,9 @@ pub trait HirDatabase: DefDatabase {
 
     #[salsa::invoke(crate::ty::method_resolution::CrateImplBlocks::impls_in_crate_query)]
     fn impls_in_crate(&self, krate: Crate) -> Arc<CrateImplBlocks>;
+
+    #[salsa::invoke(crate::ty::method_resolution::implements)]
+    fn implements(&self, trait_ref: TraitRef) -> bool;
 }
 
 #[test]
diff --git a/crates/ra_hir/src/diagnostics.rs b/crates/ra_hir/src/diagnostics.rs
new file mode 100644
index 000000000..d6a51b833
--- /dev/null
+++ b/crates/ra_hir/src/diagnostics.rs
@@ -0,0 +1,115 @@
+use std::{fmt, any::Any};
+
+use ra_syntax::{SyntaxNodePtr, TreeArc, AstPtr, TextRange, ast, SyntaxNode};
+use relative_path::RelativePathBuf;
+
+use crate::{HirFileId, HirDatabase};
+
+/// Diagnostic defines hir API for errors and warnings.
+///
+/// It is used as a `dyn` object, which you can downcast to a concrete
+/// diagnostic. DiagnosticSink are structured, meaning that they include rich
+/// information which can be used by IDE to create fixes. DiagnosticSink are
+/// expressed in terms of macro-expanded syntax tree nodes (so, it's a bad idea
+/// to diagnostic in a salsa value).
+///
+/// Internally, various subsystems of hir produce diagnostics specific to a
+/// subsystem (typically, an `enum`), which are safe to store in salsa but do not
+/// include source locations. Such internal diagnostic are transformed into an
+/// instance of `Diagnostic` on demand.
+pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
+    fn message(&self) -> String;
+    fn file(&self) -> HirFileId;
+    fn syntax_node_ptr(&self) -> SyntaxNodePtr;
+    fn highlight_range(&self) -> TextRange {
+        self.syntax_node_ptr().range()
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static);
+}
+
+impl dyn Diagnostic {
+    pub fn syntax_node(&self, db: &impl HirDatabase) -> TreeArc<SyntaxNode> {
+        let source_file = db.hir_parse(self.file());
+        self.syntax_node_ptr().to_node(&source_file).to_owned()
+    }
+    pub fn downcast_ref<D: Diagnostic>(&self) -> Option<&D> {
+        self.as_any().downcast_ref()
+    }
+}
+
+pub struct DiagnosticSink<'a> {
+    callbacks: Vec<Box<dyn FnMut(&dyn Diagnostic) -> Result<(), ()> + 'a>>,
+    default_callback: Box<dyn FnMut(&dyn Diagnostic) + 'a>,
+}
+
+impl<'a> DiagnosticSink<'a> {
+    pub fn new(cb: impl FnMut(&dyn Diagnostic) + 'a) -> DiagnosticSink<'a> {
+        DiagnosticSink { callbacks: Vec::new(), default_callback: Box::new(cb) }
+    }
+
+    pub fn on<D: Diagnostic, F: FnMut(&D) + 'a>(mut self, mut cb: F) -> DiagnosticSink<'a> {
+        let cb = move |diag: &dyn Diagnostic| match diag.downcast_ref::<D>() {
+            Some(d) => {
+                cb(d);
+                Ok(())
+            }
+            None => Err(()),
+        };
+        self.callbacks.push(Box::new(cb));
+        self
+    }
+
+    pub(crate) fn push(&mut self, d: impl Diagnostic) {
+        let d: &dyn Diagnostic = &d;
+        for cb in self.callbacks.iter_mut() {
+            match cb(d) {
+                Ok(()) => return,
+                Err(()) => (),
+            }
+        }
+        (self.default_callback)(d)
+    }
+}
+
+#[derive(Debug)]
+pub struct NoSuchField {
+    pub file: HirFileId,
+    pub field: AstPtr<ast::NamedField>,
+}
+
+impl Diagnostic for NoSuchField {
+    fn message(&self) -> String {
+        "no such field".to_string()
+    }
+    fn file(&self) -> HirFileId {
+        self.file
+    }
+    fn syntax_node_ptr(&self) -> SyntaxNodePtr {
+        self.field.into()
+    }
+    fn as_any(&self) -> &(Any + Send + 'static) {
+        self
+    }
+}
+
+#[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 file(&self) -> HirFileId {
+        self.file
+    }
+    fn syntax_node_ptr(&self) -> SyntaxNodePtr {
+        self.decl.into()
+    }
+    fn as_any(&self) -> &(Any + Send + 'static) {
+        self
+    }
+}
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index c37fd0454..a85422955 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -5,7 +5,7 @@ use rustc_hash::FxHashMap;
 
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use ra_syntax::{
-    SyntaxNodePtr, AstNode,
+    SyntaxNodePtr, AstPtr, AstNode,
     ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralFlavor, TypeAscriptionOwner}
 };
 
@@ -54,6 +54,7 @@ pub struct BodySourceMap {
     expr_map_back: ArenaMap<ExprId, SyntaxNodePtr>,
     pat_map: FxHashMap<SyntaxNodePtr, PatId>,
     pat_map_back: ArenaMap<PatId, SyntaxNodePtr>,
+    field_map: FxHashMap<(ExprId, usize), AstPtr<ast::NamedField>>,
 }
 
 impl Body {
@@ -138,6 +139,10 @@ impl BodySourceMap {
     pub fn node_pat(&self, node: &ast::Pat) -> Option<PatId> {
         self.pat_map.get(&SyntaxNodePtr::new(node.syntax())).cloned()
     }
+
+    pub fn field_syntax(&self, expr: ExprId, field: usize) -> AstPtr<ast::NamedField> {
+        self.field_map[&(expr, field)].clone()
+    }
 }
 
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -629,8 +634,10 @@ impl ExprCollector {
             }
             ast::ExprKind::StructLit(e) => {
                 let path = e.path().and_then(Path::from_ast);
+                let mut field_ptrs = Vec::new();
                 let fields = if let Some(nfl) = e.named_field_list() {
                     nfl.fields()
+                        .inspect(|field| field_ptrs.push(AstPtr::new(*field)))
                         .map(|field| StructLitField {
                             name: field
                                 .name_ref()
@@ -657,7 +664,11 @@ impl ExprCollector {
                     Vec::new()
                 };
                 let spread = e.spread().map(|s| self.collect_expr(s));
-                self.alloc_expr(Expr::StructLit { path, fields, spread }, syntax_ptr)
+                let res = self.alloc_expr(Expr::StructLit { path, fields, spread }, syntax_ptr);
+                for (i, ptr) in field_ptrs.into_iter().enumerate() {
+                    self.source_map.field_map.insert((res, i), ptr);
+                }
+                res
             }
             ast::ExprKind::FieldExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 18401f865..eb9939df7 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,16 +1,15 @@
 use std::{
-    marker::PhantomData,
     hash::{Hash, Hasher},
     sync::Arc,
 };
 
 use ra_db::{LocationInterner, FileId};
-use ra_syntax::{TreeArc, SyntaxNode, SourceFile, AstNode, SyntaxNodePtr, ast};
-use ra_arena::{Arena, RawId, ArenaId, impl_arena_id};
+use ra_syntax::{TreeArc, SourceFile, AstNode, ast};
+use ra_arena::{RawId, ArenaId, impl_arena_id};
+use mbe::MacroRules;
 
 use crate::{
-    Module,
-    DefDatabase,
+    Module, DefDatabase, AstId, FileAstId,
 };
 
 #[derive(Debug, Default)]
@@ -22,7 +21,7 @@ pub struct HirInterner {
     consts: LocationInterner<ItemLoc<ast::ConstDef>, ConstId>,
     statics: LocationInterner<ItemLoc<ast::StaticDef>, StaticId>,
     traits: LocationInterner<ItemLoc<ast::TraitDef>, TraitId>,
-    types: LocationInterner<ItemLoc<ast::TypeAliasDef>, TypeId>,
+    types: LocationInterner<ItemLoc<ast::TypeAliasDef>, TypeAliasId>,
 }
 
 impl HirInterner {
@@ -68,7 +67,7 @@ impl HirFileId {
             HirFileIdRepr::File(file_id) => file_id,
             HirFileIdRepr::Macro(macro_call_id) => {
                 let loc = macro_call_id.loc(db);
-                loc.source_item_id.file_id.original_file(db)
+                loc.ast_id.file_id().original_file(db)
             }
         }
     }
@@ -83,7 +82,10 @@ impl HirFileId {
         }
     }
 
-    pub(crate) fn hir_parse(db: &impl DefDatabase, file_id: HirFileId) -> TreeArc<SourceFile> {
+    pub(crate) fn hir_parse_query(
+        db: &impl DefDatabase,
+        file_id: HirFileId,
+    ) -> TreeArc<SourceFile> {
         match file_id.0 {
             HirFileIdRepr::File(file_id) => db.parse(file_id),
             HirFileIdRepr::Macro(macro_call_id) => {
@@ -96,14 +98,10 @@ impl HirFileId {
 
 fn parse_macro(db: &impl DefDatabase, macro_call_id: MacroCallId) -> Option<TreeArc<SourceFile>> {
     let loc = macro_call_id.loc(db);
-    let syntax = db.file_item(loc.source_item_id);
-    let macro_call = ast::MacroCall::cast(&syntax).unwrap();
+    let macro_call = loc.ast_id.to_node(db);
     let (macro_arg, _) = macro_call.token_tree().and_then(mbe::ast_to_token_tree)?;
 
-    let def_map = db.crate_def_map(loc.module.krate);
-    let (krate, macro_id) = def_map.resolve_macro(macro_call_id)?;
-    let def_map = db.crate_def_map(krate);
-    let macro_rules = &def_map[macro_id];
+    let macro_rules = db.macro_def(loc.def)?;
     let tt = macro_rules.expand(&macro_arg).ok()?;
     Some(mbe::token_tree_to_ast_item_list(&tt))
 }
@@ -126,6 +124,17 @@ impl From<MacroCallId> for HirFileId {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct MacroDefId(pub(crate) AstId<ast::MacroCall>);
+
+pub(crate) fn macro_def_query(db: &impl DefDatabase, id: MacroDefId) -> Option<Arc<MacroRules>> {
+    let macro_call = id.0.to_node(db);
+    let arg = macro_call.token_tree()?;
+    let (tt, _) = mbe::ast_to_token_tree(arg)?;
+    let rules = MacroRules::parse(&tt).ok()?;
+    Some(Arc::new(rules))
+}
+
 /// `MacroCallId` identifies a particular macro invocation, like
 /// `println!("Hello, {}", world)`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -134,8 +143,8 @@ impl_arena_id!(MacroCallId);
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct MacroCallLoc {
-    pub(crate) module: Module,
-    pub(crate) source_item_id: SourceItemId,
+    pub(crate) def: MacroDefId,
+    pub(crate) ast_id: AstId<ast::MacroCall>,
 }
 
 impl MacroCallId {
@@ -145,7 +154,6 @@ impl MacroCallId {
 }
 
 impl MacroCallLoc {
-    #[allow(unused)]
     pub(crate) fn id(&self, db: &impl AsRef<HirInterner>) -> MacroCallId {
         db.as_ref().macros.loc2id(&self)
     }
@@ -154,26 +162,25 @@ impl MacroCallLoc {
 #[derive(Debug)]
 pub struct ItemLoc<N: AstNode> {
     pub(crate) module: Module,
-    raw: SourceItemId,
-    _ty: PhantomData<N>,
+    ast_id: AstId<N>,
 }
 
 impl<N: AstNode> PartialEq for ItemLoc<N> {
     fn eq(&self, other: &Self) -> bool {
-        self.module == other.module && self.raw == other.raw
+        self.module == other.module && self.ast_id == other.ast_id
     }
 }
 impl<N: AstNode> Eq for ItemLoc<N> {}
 impl<N: AstNode> Hash for ItemLoc<N> {
     fn hash<H: Hasher>(&self, hasher: &mut H) {
         self.module.hash(hasher);
-        self.raw.hash(hasher);
+        self.ast_id.hash(hasher);
     }
 }
 
 impl<N: AstNode> Clone for ItemLoc<N> {
     fn clone(&self) -> ItemLoc<N> {
-        ItemLoc { module: self.module, raw: self.raw, _ty: PhantomData }
+        ItemLoc { module: self.module, ast_id: self.ast_id }
     }
 }
 
@@ -200,26 +207,19 @@ impl<'a, DB: DefDatabase> LocationCtx<&'a DB> {
 pub(crate) trait AstItemDef<N: AstNode>: ArenaId + Clone {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<N>, Self>;
     fn from_ast(ctx: LocationCtx<&impl DefDatabase>, ast: &N) -> Self {
-        let items = ctx.db.file_items(ctx.file_id);
-        let item_id = items.id_of(ctx.file_id, ast.syntax());
-        Self::from_source_item_id_unchecked(ctx, item_id)
+        let items = ctx.db.ast_id_map(ctx.file_id);
+        let item_id = items.ast_id(ast);
+        Self::from_ast_id(ctx, item_id)
     }
-    fn from_source_item_id_unchecked(
-        ctx: LocationCtx<&impl DefDatabase>,
-        item_id: SourceFileItemId,
-    ) -> Self {
-        let raw = SourceItemId { file_id: ctx.file_id, item_id };
-        let loc = ItemLoc { module: ctx.module, raw, _ty: PhantomData };
-
+    fn from_ast_id(ctx: LocationCtx<&impl DefDatabase>, ast_id: FileAstId<N>) -> Self {
+        let loc = ItemLoc { module: ctx.module, ast_id: ast_id.with_file_id(ctx.file_id) };
         Self::interner(ctx.db.as_ref()).loc2id(&loc)
     }
     fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<N>) {
         let int = Self::interner(db.as_ref());
         let loc = int.id2loc(self);
-        let syntax = db.file_item(loc.raw);
-        let ast =
-            N::cast(&syntax).unwrap_or_else(|| panic!("invalid ItemLoc: {:?}", loc.raw)).to_owned();
-        (loc.raw.file_id, ast)
+        let ast = loc.ast_id.to_node(db);
+        (loc.ast_id.file_id(), ast)
     }
     fn module(self, db: &impl DefDatabase) -> Module {
         let int = Self::interner(db.as_ref());
@@ -229,7 +229,7 @@ pub(crate) trait AstItemDef<N: AstNode>: ArenaId + Clone {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct FunctionId(RawId);
+pub(crate) struct FunctionId(RawId);
 impl_arena_id!(FunctionId);
 impl AstItemDef<ast::FnDef> for FunctionId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::FnDef>, Self> {
@@ -238,7 +238,7 @@ impl AstItemDef<ast::FnDef> for FunctionId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StructId(RawId);
+pub(crate) struct StructId(RawId);
 impl_arena_id!(StructId);
 impl AstItemDef<ast::StructDef> for StructId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::StructDef>, Self> {
@@ -247,7 +247,7 @@ impl AstItemDef<ast::StructDef> for StructId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct EnumId(RawId);
+pub(crate) struct EnumId(RawId);
 impl_arena_id!(EnumId);
 impl AstItemDef<ast::EnumDef> for EnumId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::EnumDef>, Self> {
@@ -256,7 +256,7 @@ impl AstItemDef<ast::EnumDef> for EnumId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct ConstId(RawId);
+pub(crate) struct ConstId(RawId);
 impl_arena_id!(ConstId);
 impl AstItemDef<ast::ConstDef> for ConstId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::ConstDef>, Self> {
@@ -265,7 +265,7 @@ impl AstItemDef<ast::ConstDef> for ConstId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StaticId(RawId);
+pub(crate) struct StaticId(RawId);
 impl_arena_id!(StaticId);
 impl AstItemDef<ast::StaticDef> for StaticId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::StaticDef>, Self> {
@@ -274,7 +274,7 @@ impl AstItemDef<ast::StaticDef> for StaticId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TraitId(RawId);
+pub(crate) struct TraitId(RawId);
 impl_arena_id!(TraitId);
 impl AstItemDef<ast::TraitDef> for TraitId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::TraitDef>, Self> {
@@ -283,117 +283,10 @@ impl AstItemDef<ast::TraitDef> for TraitId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct TypeId(RawId);
-impl_arena_id!(TypeId);
-impl AstItemDef<ast::TypeAliasDef> for TypeId {
+pub(crate) struct TypeAliasId(RawId);
+impl_arena_id!(TypeAliasId);
+impl AstItemDef<ast::TypeAliasDef> for TypeAliasId {
     fn interner(interner: &HirInterner) -> &LocationInterner<ItemLoc<ast::TypeAliasDef>, Self> {
         &interner.types
     }
 }
-
-/// Identifier of item within a specific file. This is stable over reparses, so
-/// it's OK to use it as a salsa key/value.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct SourceFileItemId(RawId);
-impl_arena_id!(SourceFileItemId);
-
-impl SourceFileItemId {
-    pub(crate) fn with_file_id(self, file_id: HirFileId) -> SourceItemId {
-        SourceItemId { file_id, item_id: self }
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct SourceItemId {
-    pub(crate) file_id: HirFileId,
-    pub(crate) item_id: SourceFileItemId,
-}
-
-/// Maps items' `SyntaxNode`s to `SourceFileItemId`s and back.
-#[derive(Debug, PartialEq, Eq)]
-pub struct SourceFileItems {
-    file_id: HirFileId,
-    arena: Arena<SourceFileItemId, SyntaxNodePtr>,
-}
-
-impl SourceFileItems {
-    pub(crate) fn file_items_query(
-        db: &impl DefDatabase,
-        file_id: HirFileId,
-    ) -> Arc<SourceFileItems> {
-        let source_file = db.hir_parse(file_id);
-        Arc::new(SourceFileItems::from_source_file(&source_file, file_id))
-    }
-
-    pub(crate) fn file_item_query(
-        db: &impl DefDatabase,
-        source_item_id: SourceItemId,
-    ) -> TreeArc<SyntaxNode> {
-        let source_file = db.hir_parse(source_item_id.file_id);
-        db.file_items(source_item_id.file_id)[source_item_id.item_id]
-            .to_node(&source_file)
-            .to_owned()
-    }
-
-    pub(crate) fn from_source_file(
-        source_file: &SourceFile,
-        file_id: HirFileId,
-    ) -> SourceFileItems {
-        let mut res = SourceFileItems { file_id, arena: Arena::default() };
-        // By walking the tree in bread-first order we make sure that parents
-        // get lower ids then children. That is, adding a new child does not
-        // change parent's id. This means that, say, adding a new function to a
-        // trait does not change ids of top-level items, which helps caching.
-        bfs(source_file.syntax(), |it| {
-            if let Some(module_item) = ast::ModuleItem::cast(it) {
-                res.alloc(module_item.syntax());
-            } else if let Some(macro_call) = ast::MacroCall::cast(it) {
-                res.alloc(macro_call.syntax());
-            }
-        });
-        res
-    }
-
-    fn alloc(&mut self, item: &SyntaxNode) -> SourceFileItemId {
-        self.arena.alloc(SyntaxNodePtr::new(item))
-    }
-    pub(crate) fn id_of(&self, file_id: HirFileId, item: &SyntaxNode) -> SourceFileItemId {
-        assert_eq!(
-            self.file_id, file_id,
-            "SourceFileItems: wrong file, expected {:?}, got {:?}",
-            self.file_id, file_id
-        );
-        self.id_of_unchecked(item)
-    }
-    pub(crate) fn id_of_unchecked(&self, item: &SyntaxNode) -> SourceFileItemId {
-        let ptr = SyntaxNodePtr::new(item);
-        if let Some((id, _)) = self.arena.iter().find(|(_id, i)| **i == ptr) {
-            return id;
-        }
-        panic!(
-            "Can't find {:?} in SourceFileItems:\n{:?}",
-            item,
-            self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
-        );
-    }
-}
-
-impl std::ops::Index<SourceFileItemId> for SourceFileItems {
-    type Output = SyntaxNodePtr;
-    fn index(&self, idx: SourceFileItemId) -> &SyntaxNodePtr {
-        &self.arena[idx]
-    }
-}
-
-/// Walks the subtree in bfs order, calling `f` for each node.
-fn bfs(node: &SyntaxNode, mut f: impl FnMut(&SyntaxNode)) {
-    let mut curr_layer = vec![node];
-    let mut next_layer = vec![];
-    while !curr_layer.is_empty() {
-        curr_layer.drain(..).for_each(|node| {
-            next_layer.extend(node.children());
-            f(node);
-        });
-        std::mem::swap(&mut curr_layer, &mut next_layer);
-    }
-}
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index a89c916f8..7c603bbd3 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -23,10 +23,12 @@ pub mod mock;
 mod path;
 pub mod source_binder;
 
+mod source_id;
 mod ids;
 mod name;
 mod nameres;
 mod adt;
+mod traits;
 mod type_alias;
 mod type_ref;
 mod ty;
@@ -35,6 +37,7 @@ mod expr;
 mod generics;
 mod docs;
 mod resolve;
+pub mod diagnostics;
 
 mod code_model_api;
 mod code_model_impl;
@@ -45,13 +48,14 @@ mod marks;
 use crate::{
     db::{HirDatabase, DefDatabase},
     name::{AsName, KnownName},
-    ids::{SourceItemId, SourceFileItems},
+    source_id::{FileAstId, AstId},
 };
 
 pub use self::{
     path::{Path, PathKind},
     name::Name,
-    ids::{HirFileId, MacroCallId, MacroCallLoc, HirInterner},
+    source_id::{AstIdMap, ErasedFileAstId},
+    ids::{HirFileId, MacroDefId, MacroCallId, MacroCallLoc, HirInterner},
     nameres::{PerNs, Namespace},
     ty::{Ty, ApplicationTy, TypeCtor, Substs, display::HirDisplay},
     impl_block::{ImplBlock, ImplItem},
@@ -63,7 +67,7 @@ pub use self::{
 
 pub use self::code_model_api::{
     Crate, CrateDependency,
-    Module, ModuleDef, ModuleSource, Problem,
+    Module, ModuleDef, ModuleSource,
     Struct, Enum, EnumVariant,
     Function, FnSignature,
     StructField, FieldSource,
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 10d4c1b8c..aeab6b180 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -9,7 +9,7 @@ use relative_path::RelativePathBuf;
 use test_utils::{parse_fixture, CURSOR_MARKER, extract_offset};
 use rustc_hash::FxHashMap;
 
-use crate::{db, HirInterner};
+use crate::{db, HirInterner, diagnostics::DiagnosticSink};
 
 pub const WORKSPACE: SourceRootId = SourceRootId(0);
 
@@ -70,6 +70,22 @@ impl MockDatabase {
         self.set_crate_graph(Arc::new(crate_graph))
     }
 
+    pub fn diagnostics(&self) -> String {
+        let mut buf = String::from("\n");
+        let mut files: Vec<FileId> = self.files.values().map(|&it| it).collect();
+        files.sort();
+        for file in files {
+            let module = crate::source_binder::module_from_file_id(self, file).unwrap();
+            module.diagnostics(
+                self,
+                &mut DiagnosticSink::new(|d| {
+                    buf += &format!("{:?}: {}\n", d.syntax_node(self).text(), d.message());
+                }),
+            )
+        }
+        buf
+    }
+
     fn from_fixture(fixture: &str) -> (MockDatabase, Option<FilePosition>) {
         let mut db = MockDatabase::default();
 
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 5ac878c79..8adc6d368 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -59,12 +59,16 @@ use rustc_hash::FxHashMap;
 use ra_arena::{Arena, RawId, impl_arena_id};
 use ra_db::{FileId, Edition};
 use test_utils::tested_by;
+use ra_syntax::ast;
 use ra_prof::profile;
 
 use crate::{
-    ModuleDef, Name, Crate, Module, Problem,
-    DefDatabase, Path, PathKind, HirFileId,
-    ids::{SourceItemId, SourceFileItemId, MacroCallId},
+    ModuleDef, Name, Crate, Module,
+    DefDatabase, Path, PathKind, HirFileId, Trait,
+    ids::MacroDefId,
+    diagnostics::DiagnosticSink,
+    nameres::diagnostics::DefDiagnostic,
+    AstId,
 };
 
 pub(crate) use self::raw::{RawItems, ImportId, ImportSourceMap};
@@ -83,10 +87,8 @@ pub struct CrateDefMap {
     extern_prelude: FxHashMap<Name, ModuleDef>,
     root: CrateModuleId,
     modules: Arena<CrateModuleId, ModuleData>,
-    macros: Arena<CrateMacroId, mbe::MacroRules>,
-    public_macros: FxHashMap<Name, CrateMacroId>,
-    macro_resolutions: FxHashMap<MacroCallId, (Crate, CrateMacroId)>,
-    problems: CrateDefMapProblems,
+    public_macros: FxHashMap<Name, MacroDefId>,
+    diagnostics: Vec<DefDiagnostic>,
 }
 
 impl std::ops::Index<CrateModuleId> for CrateDefMap {
@@ -96,18 +98,6 @@ impl std::ops::Index<CrateModuleId> for CrateDefMap {
     }
 }
 
-impl std::ops::Index<CrateMacroId> for CrateDefMap {
-    type Output = mbe::MacroRules;
-    fn index(&self, id: CrateMacroId) -> &mbe::MacroRules {
-        &self.macros[id]
-    }
-}
-
-/// An ID of a macro, **local** to a specific crate
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub(crate) struct CrateMacroId(RawId);
-impl_arena_id!(CrateMacroId);
-
 /// An ID of a module, **local** to a specific crate
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub(crate) struct CrateModuleId(RawId);
@@ -119,28 +109,13 @@ pub(crate) struct ModuleData {
     pub(crate) children: FxHashMap<Name, CrateModuleId>,
     pub(crate) scope: ModuleScope,
     /// None for root
-    pub(crate) declaration: Option<SourceItemId>,
+    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(Default, Debug, PartialEq, Eq)]
-pub(crate) struct CrateDefMapProblems {
-    problems: Vec<(SourceItemId, Problem)>,
-}
-
-impl CrateDefMapProblems {
-    fn add(&mut self, source_item_id: SourceItemId, problem: Problem) {
-        self.problems.push((source_item_id, problem))
-    }
-
-    pub(crate) fn iter<'a>(&'a self) -> impl Iterator<Item = (&'a SourceItemId, &'a Problem)> + 'a {
-        self.problems.iter().map(|(s, p)| (s, p))
-    }
-}
-
 #[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct ModuleScope {
     items: FxHashMap<Name, Resolution>,
@@ -153,6 +128,12 @@ impl ModuleScope {
     pub fn get(&self, name: &Name) -> Option<&Resolution> {
         self.items.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,
+        })
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
@@ -210,10 +191,8 @@ impl CrateDefMap {
                 prelude: None,
                 root,
                 modules,
-                macros: Arena::default(),
                 public_macros: FxHashMap::default(),
-                macro_resolutions: FxHashMap::default(),
-                problems: CrateDefMapProblems::default(),
+                diagnostics: Vec::new(),
             }
         };
         let def_map = collector::collect_defs(db, def_map);
@@ -224,10 +203,6 @@ impl CrateDefMap {
         self.root
     }
 
-    pub(crate) fn problems(&self) -> &CrateDefMapProblems {
-        &self.problems
-    }
-
     pub(crate) fn mk_module(&self, module_id: CrateModuleId) -> Module {
         Module { krate: self.krate, module_id }
     }
@@ -240,19 +215,20 @@ impl CrateDefMap {
         &self.extern_prelude
     }
 
-    pub(crate) fn resolve_macro(
+    pub(crate) fn add_diagnostics(
         &self,
-        macro_call_id: MacroCallId,
-    ) -> Option<(Crate, CrateMacroId)> {
-        self.macro_resolutions.get(&macro_call_id).map(|&it| it)
+        db: &impl DefDatabase,
+        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<SourceFileItemId>,
+        decl_id: Option<AstId<ast::Module>>,
     ) -> Option<CrateModuleId> {
-        let decl_id = decl_id.map(|it| it.with_file_id(file_id));
         let (module_id, _module_data) = self.modules.iter().find(|(_module_id, module_data)| {
             if decl_id.is_some() {
                 module_data.declaration == decl_id
@@ -452,3 +428,46 @@ impl CrateDefMap {
         }
     }
 }
+
+mod diagnostics {
+    use relative_path::RelativePathBuf;
+    use ra_syntax::{AstPtr, ast};
+
+    use crate::{
+        AstId, DefDatabase,
+        nameres::CrateModuleId,
+        diagnostics::{DiagnosticSink, UnresolvedModule},
+};
+
+    #[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,
+            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/src/nameres/collector.rs
index c5b73cfbe..39cadc94a 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -3,17 +3,22 @@ use rustc_hash::FxHashMap;
 use relative_path::RelativePathBuf;
 use test_utils::tested_by;
 use ra_db::FileId;
+use ra_syntax::ast;
 
 use crate::{
     Function, Module, Struct, Enum, Const, Static, Trait, TypeAlias,
-    DefDatabase, HirFileId, Name, Path, Problem, Crate,
+    DefDatabase, HirFileId, Name, Path,
     KnownName,
-    nameres::{Resolution, PerNs, ModuleDef, ReachedFixedPoint, ResolveMode, raw},
-    ids::{AstItemDef, LocationCtx, MacroCallLoc, SourceItemId, MacroCallId},
+    nameres::{
+        Resolution, PerNs, ModuleDef, ReachedFixedPoint, ResolveMode,
+        CrateDefMap, CrateModuleId, ModuleData,
+        diagnostics::DefDiagnostic,
+        raw,
+    },
+    ids::{AstItemDef, LocationCtx, MacroCallLoc, MacroCallId, MacroDefId},
+    AstId,
 };
 
-use super::{CrateDefMap, CrateModuleId, ModuleData, CrateMacroId};
-
 pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> CrateDefMap {
     // populate external prelude
     for dep in def_map.krate.dependencies(db) {
@@ -48,8 +53,8 @@ struct DefCollector<DB> {
     def_map: CrateDefMap,
     glob_imports: FxHashMap<CrateModuleId, Vec<(CrateModuleId, raw::ImportId)>>,
     unresolved_imports: Vec<(CrateModuleId, raw::ImportId, raw::ImportData)>,
-    unexpanded_macros: Vec<(CrateModuleId, MacroCallId, Path, tt::Subtree)>,
-    global_macro_scope: FxHashMap<Name, CrateMacroId>,
+    unexpanded_macros: Vec<(CrateModuleId, AstId<ast::MacroCall>, Path)>,
+    global_macro_scope: FxHashMap<Name, MacroDefId>,
 }
 
 impl<'a, DB> DefCollector<&'a DB>
@@ -59,7 +64,7 @@ where
     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 raw_items = self.db.raw_items(file_id);
+        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);
         ModCollector {
@@ -90,14 +95,11 @@ where
         }
     }
 
-    fn define_macro(&mut self, name: Name, tt: &tt::Subtree, export: bool) {
-        if let Ok(rules) = mbe::MacroRules::parse(tt) {
-            let macro_id = self.def_map.macros.alloc(rules);
-            if export {
-                self.def_map.public_macros.insert(name.clone(), macro_id);
-            }
-            self.global_macro_scope.insert(name, macro_id);
+    fn define_macro(&mut self, name: Name, macro_id: MacroDefId, export: bool) {
+        if export {
+            self.def_map.public_macros.insert(name.clone(), macro_id);
         }
+        self.global_macro_scope.insert(name, macro_id);
     }
 
     fn resolve_imports(&mut self) -> ReachedFixedPoint {
@@ -293,7 +295,7 @@ where
         let mut macros = std::mem::replace(&mut self.unexpanded_macros, Vec::new());
         let mut resolved = Vec::new();
         let mut res = ReachedFixedPoint::Yes;
-        macros.retain(|(module_id, call_id, path, tt)| {
+        macros.retain(|(module_id, ast_id, path)| {
             if path.segments.len() != 2 {
                 return true;
             }
@@ -309,47 +311,23 @@ where
             res = ReachedFixedPoint::No;
             let def_map = self.db.crate_def_map(krate);
             if let Some(macro_id) = def_map.public_macros.get(&path.segments[1].name).cloned() {
-                resolved.push((*module_id, *call_id, (krate, macro_id), tt.clone()));
+                let call_id = MacroCallLoc { def: macro_id, ast_id: *ast_id }.id(self.db);
+                resolved.push((*module_id, call_id));
             }
             false
         });
 
-        for (module_id, macro_call_id, macro_def_id, arg) in resolved {
-            self.collect_macro_expansion(module_id, macro_call_id, macro_def_id, arg);
+        for (module_id, macro_call_id) in resolved {
+            self.collect_macro_expansion(module_id, macro_call_id);
         }
         res
     }
 
-    fn collect_macro_expansion(
-        &mut self,
-        module_id: CrateModuleId,
-        macro_call_id: MacroCallId,
-        macro_def_id: (Crate, CrateMacroId),
-        macro_arg: tt::Subtree,
-    ) {
-        let (macro_krate, macro_id) = macro_def_id;
-        let dm;
-        let rules = if macro_krate == self.def_map.krate {
-            &self.def_map[macro_id]
-        } else {
-            dm = self.db.crate_def_map(macro_krate);
-            &dm[macro_id]
-        };
-        if let Ok(expansion) = rules.expand(&macro_arg) {
-            self.def_map.macro_resolutions.insert(macro_call_id, macro_def_id);
-            // XXX: this **does not** go through a database, because we can't
-            // identify macro_call without adding the whole state of name resolution
-            // as a parameter to the query.
-            //
-            // So, we run the queries "manually" and we must ensure that
-            // `db.hir_parse(macro_call_id)` returns the same source_file.
-            let file_id: HirFileId = macro_call_id.into();
-            let source_file = mbe::token_tree_to_ast_item_list(&expansion);
-
-            let raw_items = raw::RawItems::from_source_file(&source_file, file_id);
-            ModCollector { def_collector: &mut *self, file_id, module_id, raw_items: &raw_items }
-                .collect(raw_items.items())
-        }
+    fn collect_macro_expansion(&mut self, module_id: CrateModuleId, macro_call_id: MacroCallId) {
+        let file_id: HirFileId = macro_call_id.into();
+        let raw_items = self.db.raw_items(file_id);
+        ModCollector { def_collector: &mut *self, file_id, module_id, raw_items: &raw_items }
+            .collect(raw_items.items())
     }
 
     fn finish(self) -> CrateDefMap {
@@ -387,12 +365,9 @@ where
     fn collect_module(&mut self, module: &raw::ModuleData) {
         match module {
             // inline module, just recurse
-            raw::ModuleData::Definition { name, items, source_item_id } => {
-                let module_id = self.push_child_module(
-                    name.clone(),
-                    source_item_id.with_file_id(self.file_id),
-                    None,
-                );
+            raw::ModuleData::Definition { name, items, ast_id } => {
+                let module_id =
+                    self.push_child_module(name.clone(), ast_id.with_file_id(self.file_id), None);
                 ModCollector {
                     def_collector: &mut *self.def_collector,
                     module_id,
@@ -402,28 +377,29 @@ where
                 .collect(&*items);
             }
             // out of line module, resovle, parse and recurse
-            raw::ModuleData::Declaration { name, source_item_id } => {
-                let source_item_id = source_item_id.with_file_id(self.file_id);
+            raw::ModuleData::Declaration { name, ast_id } => {
+                let ast_id = ast_id.with_file_id(self.file_id);
                 let is_root = self.def_collector.def_map.modules[self.module_id].parent.is_none();
-                let (file_ids, problem) =
-                    resolve_submodule(self.def_collector.db, self.file_id, name, is_root);
-
-                if let Some(problem) = problem {
-                    self.def_collector.def_map.problems.add(source_item_id, problem)
-                }
-
-                if let Some(&file_id) = file_ids.first() {
-                    let module_id =
-                        self.push_child_module(name.clone(), source_item_id, Some(file_id));
-                    let raw_items = self.def_collector.db.raw_items(file_id);
-                    ModCollector {
-                        def_collector: &mut *self.def_collector,
-                        module_id,
-                        file_id: file_id.into(),
-                        raw_items: &raw_items,
+                match resolve_submodule(self.def_collector.db, self.file_id, name, is_root) {
+                    Ok(file_id) => {
+                        let module_id = self.push_child_module(name.clone(), ast_id, Some(file_id));
+                        let raw_items = self.def_collector.db.raw_items(file_id.into());
+                        ModCollector {
+                            def_collector: &mut *self.def_collector,
+                            module_id,
+                            file_id: file_id.into(),
+                            raw_items: &raw_items,
+                        }
+                        .collect(raw_items.items())
                     }
-                    .collect(raw_items.items())
-                }
+                    Err(candidate) => self.def_collector.def_map.diagnostics.push(
+                        DefDiagnostic::UnresolvedModule {
+                            module: self.module_id,
+                            declaration: ast_id,
+                            candidate,
+                        },
+                    ),
+                };
             }
         }
     }
@@ -431,7 +407,7 @@ where
     fn push_child_module(
         &mut self,
         name: Name,
-        declaration: SourceItemId,
+        declaration: AstId<ast::Module>,
         definition: Option<FileId>,
     ) -> CrateModuleId {
         let modules = &mut self.def_collector.def_map.modules;
@@ -453,23 +429,24 @@ where
     fn define_def(&mut self, def: &raw::DefData) {
         let module = Module { krate: self.def_collector.def_map.krate, module_id: self.module_id };
         let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id.into());
-        macro_rules! id {
-            () => {
-                AstItemDef::from_source_item_id_unchecked(ctx, def.source_item_id)
+
+        macro_rules! def {
+            ($kind:ident, $ast_id:ident) => {
+                $kind { id: AstItemDef::from_ast_id(ctx, $ast_id) }.into()
             };
         }
         let name = def.name.clone();
         let def: PerNs<ModuleDef> = match def.kind {
-            raw::DefKind::Function => PerNs::values(Function { id: id!() }.into()),
-            raw::DefKind::Struct => {
-                let s = Struct { id: id!() }.into();
+            raw::DefKind::Function(ast_id) => PerNs::values(def!(Function, ast_id)),
+            raw::DefKind::Struct(ast_id) => {
+                let s = def!(Struct, ast_id);
                 PerNs::both(s, s)
             }
-            raw::DefKind::Enum => PerNs::types(Enum { id: id!() }.into()),
-            raw::DefKind::Const => PerNs::values(Const { id: id!() }.into()),
-            raw::DefKind::Static => PerNs::values(Static { id: id!() }.into()),
-            raw::DefKind::Trait => PerNs::types(Trait { id: id!() }.into()),
-            raw::DefKind::TypeAlias => PerNs::types(TypeAlias { id: id!() }.into()),
+            raw::DefKind::Enum(ast_id) => PerNs::types(def!(Enum, ast_id)),
+            raw::DefKind::Const(ast_id) => PerNs::values(def!(Const, ast_id)),
+            raw::DefKind::Static(ast_id) => PerNs::values(def!(Static, ast_id)),
+            raw::DefKind::Trait(ast_id) => PerNs::types(def!(Trait, ast_id)),
+            raw::DefKind::TypeAlias(ast_id) => PerNs::types(def!(TypeAlias, ast_id)),
         };
         let resolution = Resolution { def, import: None };
         self.def_collector.update(self.module_id, None, &[(name, resolution)])
@@ -479,39 +456,27 @@ where
         // Case 1: macro rules, define a macro in crate-global mutable scope
         if is_macro_rules(&mac.path) {
             if let Some(name) = &mac.name {
-                self.def_collector.define_macro(name.clone(), &mac.arg, mac.export)
+                let macro_id = MacroDefId(mac.ast_id.with_file_id(self.file_id));
+                self.def_collector.define_macro(name.clone(), macro_id, mac.export)
             }
             return;
         }
 
-        let source_item_id = SourceItemId { file_id: self.file_id, item_id: mac.source_item_id };
-        let macro_call_id = MacroCallLoc {
-            module: Module { krate: self.def_collector.def_map.krate, module_id: self.module_id },
-            source_item_id,
-        }
-        .id(self.def_collector.db);
+        let ast_id = mac.ast_id.with_file_id(self.file_id);
 
         // Case 2: try to expand macro_rules from this crate, triggering
         // recursive item collection.
         if let Some(&macro_id) =
             mac.path.as_ident().and_then(|name| self.def_collector.global_macro_scope.get(name))
         {
-            self.def_collector.collect_macro_expansion(
-                self.module_id,
-                macro_call_id,
-                (self.def_collector.def_map.krate, macro_id),
-                mac.arg.clone(),
-            );
+            let macro_call_id = MacroCallLoc { def: macro_id, ast_id }.id(self.def_collector.db);
+
+            self.def_collector.collect_macro_expansion(self.module_id, macro_call_id);
             return;
         }
 
         // Case 3: path to a macro from another crate, expand during name resolution
-        self.def_collector.unexpanded_macros.push((
-            self.module_id,
-            macro_call_id,
-            mac.path.clone(),
-            mac.arg.clone(),
-        ))
+        self.def_collector.unexpanded_macros.push((self.module_id, ast_id, mac.path.clone()))
     }
 }
 
@@ -524,7 +489,7 @@ fn resolve_submodule(
     file_id: HirFileId,
     name: &Name,
     is_root: bool,
-) -> (Vec<FileId>, Option<Problem>) {
+) -> Result<FileId, RelativePathBuf> {
     // FIXME: handle submodules of inline modules properly
     let file_id = file_id.original_file(db);
     let source_root_id = db.file_source_root(file_id);
@@ -545,17 +510,10 @@ fn resolve_submodule(
         candidates.push(file_dir_mod.clone());
     };
     let sr = db.source_root(source_root_id);
-    let points_to = candidates
-        .into_iter()
-        .filter_map(|path| sr.files.get(&path))
-        .map(|&it| it)
-        .collect::<Vec<_>>();
-    let problem = if points_to.is_empty() {
-        Some(Problem::UnresolvedModule {
-            candidate: if is_dir_owner { file_mod } else { file_dir_mod },
-        })
-    } else {
-        None
-    };
-    (points_to, problem)
+    let mut points_to = candidates.into_iter().filter_map(|path| sr.files.get(&path)).map(|&it| it);
+    // FIXME: handle ambiguity
+    match points_to.next() {
+        Some(file_id) => Ok(file_id),
+        None => Err(if is_dir_owner { file_mod } else { file_dir_mod }),
+    }
 }
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index f8ba398ec..0936229ac 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir/src/nameres/raw.rs
@@ -4,7 +4,6 @@ use std::{
 };
 
 use test_utils::tested_by;
-use ra_db::FileId;
 use ra_arena::{Arena, impl_arena_id, RawId, map::ArenaMap};
 use ra_syntax::{
     AstNode, SourceFile, AstPtr, TreeArc,
@@ -13,9 +12,13 @@ use ra_syntax::{
 
 use crate::{
     DefDatabase, Name, AsName, Path, HirFileId, ModuleSource,
-    ids::{SourceFileItemId, SourceFileItems},
+    AstIdMap, FileAstId,
 };
 
+/// `RawItems` is a set of top-level items in a file (except for impls).
+///
+/// It is the input to name resolution algorithm. `RawItems` are not invalidated
+/// on most edits.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct RawItems {
     modules: Arena<Module, ModuleData>,
@@ -32,11 +35,11 @@ pub struct ImportSourceMap {
 }
 
 impl ImportSourceMap {
-    pub(crate) fn insert(&mut self, import: ImportId, segment: &ast::PathSegment) {
+    fn insert(&mut self, import: ImportId, segment: &ast::PathSegment) {
         self.map.insert(import, AstPtr::new(segment))
     }
 
-    pub fn get(&self, source: &ModuleSource, import: ImportId) -> TreeArc<ast::PathSegment> {
+    pub(crate) fn get(&self, source: &ModuleSource, import: ImportId) -> TreeArc<ast::PathSegment> {
         let file = match source {
             ModuleSource::SourceFile(file) => &*file,
             ModuleSource::Module(m) => m.syntax().ancestors().find_map(SourceFile::cast).unwrap(),
@@ -47,40 +50,27 @@ impl ImportSourceMap {
 }
 
 impl RawItems {
-    pub(crate) fn raw_items_query(db: &impl DefDatabase, file_id: FileId) -> Arc<RawItems> {
+    pub(crate) fn raw_items_query(db: &impl DefDatabase, file_id: HirFileId) -> Arc<RawItems> {
         db.raw_items_with_source_map(file_id).0
     }
 
     pub(crate) fn raw_items_with_source_map_query(
         db: &impl DefDatabase,
-        file_id: FileId,
+        file_id: HirFileId,
     ) -> (Arc<RawItems>, Arc<ImportSourceMap>) {
         let mut collector = RawItemsCollector {
             raw_items: RawItems::default(),
-            source_file_items: db.file_items(file_id.into()),
+            source_ast_id_map: db.ast_id_map(file_id.into()),
             source_map: ImportSourceMap::default(),
         };
-        let source_file = db.parse(file_id);
+        let source_file = db.hir_parse(file_id);
         collector.process_module(None, &*source_file);
         (Arc::new(collector.raw_items), Arc::new(collector.source_map))
     }
 
-    pub(crate) fn items(&self) -> &[RawItem] {
+    pub(super) fn items(&self) -> &[RawItem] {
         &self.items
     }
-
-    // We can't use queries during name resolution for fear of cycles, so this
-    // is a query-less variant of the above function.
-    pub(crate) fn from_source_file(source_file: &SourceFile, file_id: HirFileId) -> RawItems {
-        let source_file_items = SourceFileItems::from_source_file(source_file, file_id);
-        let mut collector = RawItemsCollector {
-            raw_items: RawItems::default(),
-            source_file_items: Arc::new(source_file_items),
-            source_map: ImportSourceMap::default(),
-        };
-        collector.process_module(None, &*source_file);
-        collector.raw_items
-    }
 }
 
 impl Index<Module> for RawItems {
@@ -112,7 +102,7 @@ impl Index<Macro> for RawItems {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub(crate) enum RawItem {
+pub(super) enum RawItem {
     Module(Module),
     Import(ImportId),
     Def(Def),
@@ -120,13 +110,13 @@ pub(crate) enum RawItem {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub(crate) struct Module(RawId);
+pub(super) struct Module(RawId);
 impl_arena_id!(Module);
 
 #[derive(Debug, PartialEq, Eq)]
-pub(crate) enum ModuleData {
-    Declaration { name: Name, source_item_id: SourceFileItemId },
-    Definition { name: Name, source_item_id: SourceFileItemId, items: Vec<RawItem> },
+pub(super) enum ModuleData {
+    Declaration { name: Name, ast_id: FileAstId<ast::Module> },
+    Definition { name: Name, ast_id: FileAstId<ast::Module>, items: Vec<RawItem> },
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -135,51 +125,49 @@ impl_arena_id!(ImportId);
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ImportData {
-    pub(crate) path: Path,
-    pub(crate) alias: Option<Name>,
-    pub(crate) is_glob: bool,
-    pub(crate) is_prelude: bool,
-    pub(crate) is_extern_crate: bool,
+    pub(super) path: Path,
+    pub(super) alias: Option<Name>,
+    pub(super) is_glob: bool,
+    pub(super) is_prelude: bool,
+    pub(super) is_extern_crate: bool,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub(crate) struct Def(RawId);
+pub(super) struct Def(RawId);
 impl_arena_id!(Def);
 
 #[derive(Debug, PartialEq, Eq)]
-pub(crate) struct DefData {
-    pub(crate) source_item_id: SourceFileItemId,
-    pub(crate) name: Name,
-    pub(crate) kind: DefKind,
+pub(super) struct DefData {
+    pub(super) name: Name,
+    pub(super) kind: DefKind,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub(crate) enum DefKind {
-    Function,
-    Struct,
-    Enum,
-    Const,
-    Static,
-    Trait,
-    TypeAlias,
+pub(super) enum DefKind {
+    Function(FileAstId<ast::FnDef>),
+    Struct(FileAstId<ast::StructDef>),
+    Enum(FileAstId<ast::EnumDef>),
+    Const(FileAstId<ast::ConstDef>),
+    Static(FileAstId<ast::StaticDef>),
+    Trait(FileAstId<ast::TraitDef>),
+    TypeAlias(FileAstId<ast::TypeAliasDef>),
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub(crate) struct Macro(RawId);
+pub(super) struct Macro(RawId);
 impl_arena_id!(Macro);
 
 #[derive(Debug, PartialEq, Eq)]
-pub(crate) struct MacroData {
-    pub(crate) source_item_id: SourceFileItemId,
-    pub(crate) path: Path,
-    pub(crate) name: Option<Name>,
-    pub(crate) arg: tt::Subtree,
-    pub(crate) export: bool,
+pub(super) struct MacroData {
+    pub(super) ast_id: FileAstId<ast::MacroCall>,
+    pub(super) path: Path,
+    pub(super) name: Option<Name>,
+    pub(super) export: bool,
 }
 
 struct RawItemsCollector {
     raw_items: RawItems,
-    source_file_items: Arc<SourceFileItems>,
+    source_ast_id_map: Arc<AstIdMap>,
     source_map: ImportSourceMap,
 }
 
@@ -211,18 +199,31 @@ impl RawItemsCollector {
                 // impls don't participate in name resolution
                 return;
             }
-            ast::ModuleItemKind::StructDef(it) => (DefKind::Struct, it.name()),
-            ast::ModuleItemKind::EnumDef(it) => (DefKind::Enum, it.name()),
-            ast::ModuleItemKind::FnDef(it) => (DefKind::Function, it.name()),
-            ast::ModuleItemKind::TraitDef(it) => (DefKind::Trait, it.name()),
-            ast::ModuleItemKind::TypeAliasDef(it) => (DefKind::TypeAlias, it.name()),
-            ast::ModuleItemKind::ConstDef(it) => (DefKind::Const, it.name()),
-            ast::ModuleItemKind::StaticDef(it) => (DefKind::Static, it.name()),
+            ast::ModuleItemKind::StructDef(it) => {
+                (DefKind::Struct(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::EnumDef(it) => {
+                (DefKind::Enum(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::FnDef(it) => {
+                (DefKind::Function(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::TraitDef(it) => {
+                (DefKind::Trait(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::TypeAliasDef(it) => {
+                (DefKind::TypeAlias(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::ConstDef(it) => {
+                (DefKind::Const(self.source_ast_id_map.ast_id(it)), it.name())
+            }
+            ast::ModuleItemKind::StaticDef(it) => {
+                (DefKind::Static(self.source_ast_id_map.ast_id(it)), it.name())
+            }
         };
         if let Some(name) = name {
             let name = name.as_name();
-            let source_item_id = self.source_file_items.id_of_unchecked(item.syntax());
-            let def = self.raw_items.defs.alloc(DefData { name, kind, source_item_id });
+            let def = self.raw_items.defs.alloc(DefData { name, kind });
             self.push_item(current_module, RawItem::Def(def))
         }
     }
@@ -232,10 +233,9 @@ impl RawItemsCollector {
             Some(it) => it.as_name(),
             None => return,
         };
-        let source_item_id = self.source_file_items.id_of_unchecked(module.syntax());
+        let ast_id = self.source_ast_id_map.ast_id(module);
         if module.has_semi() {
-            let item =
-                self.raw_items.modules.alloc(ModuleData::Declaration { name, source_item_id });
+            let item = self.raw_items.modules.alloc(ModuleData::Declaration { name, ast_id });
             self.push_item(current_module, RawItem::Module(item));
             return;
         }
@@ -243,7 +243,7 @@ impl RawItemsCollector {
         if let Some(item_list) = module.item_list() {
             let item = self.raw_items.modules.alloc(ModuleData::Definition {
                 name,
-                source_item_id,
+                ast_id,
                 items: Vec::new(),
             });
             self.process_module(Some(item), item_list);
@@ -291,18 +291,15 @@ impl RawItemsCollector {
     }
 
     fn add_macro(&mut self, current_module: Option<Module>, m: &ast::MacroCall) {
-        let (path, arg) = match (
-            m.path().and_then(Path::from_ast),
-            m.token_tree().and_then(mbe::ast_to_token_tree),
-        ) {
-            (Some(path), Some((token_tree, _token_map))) => (path, token_tree),
+        let path = match m.path().and_then(Path::from_ast) {
+            Some(it) => it,
             _ => return,
         };
 
         let name = m.name().map(|it| it.as_name());
-        let source_item_id = self.source_file_items.id_of_unchecked(m.syntax());
+        let ast_id = self.source_ast_id_map.ast_id(m);
         let export = m.has_atom_attr("macro_export");
-        let m = self.raw_items.macros.alloc(MacroData { source_item_id, path, arg, name, export });
+        let m = self.raw_items.macros.alloc(MacroData { ast_id, path, name, export });
         self.push_item(current_module, RawItem::Macro(m));
     }
 
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index ac9b88520..572bd1bf7 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -552,3 +552,22 @@ foo: v
 "###
     );
 }
+
+#[test]
+fn unresolved_module_diagnostics() {
+    let diagnostics = MockDatabase::with_files(
+        r"
+        //- /lib.rs
+        mod foo;
+        mod bar;
+        mod baz {}
+        //- /foo.rs
+        ",
+    )
+    .diagnostics();
+
+    assert_snapshot_matches!(diagnostics, @r###"
+"mod bar;": unresolved module
+"###
+    );
+}
diff --git a/crates/ra_hir/src/nameres/tests/incremental.rs b/crates/ra_hir/src/nameres/tests/incremental.rs
index 698781923..001f76ac3 100644
--- a/crates/ra_hir/src/nameres/tests/incremental.rs
+++ b/crates/ra_hir/src/nameres/tests/incremental.rs
@@ -90,34 +90,44 @@ fn adding_inner_items_should_not_invalidate_def_map() {
     );
 }
 
-// It would be awesome to make this work, but it's unclear how
 #[test]
-#[ignore]
-fn typing_inside_a_function_inside_a_macro_should_not_invalidate_def_map() {
-    check_def_map_is_not_recomputed(
+fn typing_inside_a_macro_should_not_invalidate_def_map() {
+    let (mut db, pos) = MockDatabase::with_position(
         "
         //- /lib.rs
+        macro_rules! m {
+            ($ident:ident) => {
+                fn f() {
+                    $ident + $ident;
+                };
+            }
+        }
         mod foo;
 
-        use crate::foo::bar::Baz;
-
         //- /foo/mod.rs
         pub mod bar;
 
         //- /foo/bar.rs
         <|>
-        salsa::query_group! {
-            trait Baz {
-                fn foo() -> i32 { 1 + 1 }
-            }
-        }
-        ",
-        "
-        salsa::query_group! {
-            trait Baz {
-                fn foo() -> i32 { 92 }
-            }
-        }
+        m!(X);
         ",
     );
+    {
+        let events = db.log_executed(|| {
+            let module = crate::source_binder::module_from_file_id(&db, pos.file_id).unwrap();
+            let decls = module.declarations(&db);
+            assert_eq!(decls.len(), 1);
+        });
+        assert!(format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
+    db.set_file_text(pos.file_id, Arc::new("m!(Y);".to_string()));
+
+    {
+        let events = db.log_executed(|| {
+            let module = crate::source_binder::module_from_file_id(&db, pos.file_id).unwrap();
+            let decls = module.declarations(&db);
+            assert_eq!(decls.len(), 1);
+        });
+        assert!(!format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
 }
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index f28154517..2609585b1 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -11,7 +11,7 @@ use crate::{
     generics::GenericParams,
     expr::{scope::{ExprScopes, ScopeId}, PatId, Body},
     impl_block::ImplBlock,
-    path::Path,
+    path::Path, Trait
 };
 
 #[derive(Debug, Clone, Default)]
@@ -175,6 +175,21 @@ impl Resolver {
         names
     }
 
+    pub(crate) fn traits_in_scope<'a>(&'a self) -> impl Iterator<Item = Trait> + 'a {
+        // FIXME prelude
+        self.scopes
+            .iter()
+            .rev()
+            .flat_map(|scope| {
+                match scope {
+                    Scope::ModuleScope(m) => Some(m.crate_def_map[m.module_id].scope.traits()),
+                    _ => None,
+                }
+                .into_iter()
+            })
+            .flatten()
+    }
+
     fn module(&self) -> Option<(&CrateDefMap, CrateModuleId)> {
         self.scopes.iter().rev().find_map(|scope| match scope {
             Scope::ModuleScope(m) => Some((&*m.crate_def_map, m.module_id)),
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 3645b73b4..9dae4c3d1 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -15,8 +15,8 @@ use ra_syntax::{
 use crate::{
     HirDatabase, Function, Struct, Enum,
     AsName, Module, HirFileId, Crate, Trait, Resolver,
-    ids::{LocationCtx, SourceFileItemId},
-    expr
+    ids::LocationCtx,
+    expr, AstId
 };
 
 /// Locates the module by `FileId`. Picks topmost module in the file.
@@ -54,8 +54,8 @@ fn module_from_inline(
 ) -> Option<Module> {
     assert!(!module.has_semi());
     let file_id = file_id.into();
-    let file_items = db.file_items(file_id);
-    let item_id = file_items.id_of(file_id, module.syntax());
+    let ast_id_map = db.ast_id_map(file_id);
+    let item_id = ast_id_map.ast_id(module).with_file_id(file_id);
     module_from_source(db, file_id, Some(item_id))
 }
 
@@ -75,7 +75,7 @@ pub fn module_from_child_node(
 fn module_from_source(
     db: &impl HirDatabase,
     file_id: HirFileId,
-    decl_id: Option<SourceFileItemId>,
+    decl_id: Option<AstId<ast::Module>>,
 ) -> Option<Module> {
     let source_root_id = db.file_source_root(file_id.as_original_file());
     db.source_root_crates(source_root_id).iter().map(|&crate_id| Crate { crate_id }).find_map(
diff --git a/crates/ra_hir/src/source_id.rs b/crates/ra_hir/src/source_id.rs
new file mode 100644
index 000000000..0a8fb6d32
--- /dev/null
+++ b/crates/ra_hir/src/source_id.rs
@@ -0,0 +1,150 @@
+use std::{marker::PhantomData, sync::Arc, hash::{Hash, Hasher}};
+
+use ra_arena::{Arena, RawId, impl_arena_id};
+use ra_syntax::{SyntaxNodePtr, TreeArc, SyntaxNode, SourceFile, AstNode, ast};
+
+use crate::{HirFileId, DefDatabase};
+
+/// `AstId` points to an AST node in any file.
+///
+/// It is stable across reparses, and can be used as salsa key/value.
+#[derive(Debug)]
+pub(crate) struct AstId<N: AstNode> {
+    file_id: HirFileId,
+    file_ast_id: FileAstId<N>,
+}
+
+impl<N: AstNode> Clone for AstId<N> {
+    fn clone(&self) -> AstId<N> {
+        *self
+    }
+}
+impl<N: AstNode> Copy for AstId<N> {}
+
+impl<N: AstNode> PartialEq for AstId<N> {
+    fn eq(&self, other: &Self) -> bool {
+        (self.file_id, self.file_ast_id) == (other.file_id, other.file_ast_id)
+    }
+}
+impl<N: AstNode> Eq for AstId<N> {}
+impl<N: AstNode> Hash for AstId<N> {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        (self.file_id, self.file_ast_id).hash(hasher);
+    }
+}
+
+impl<N: AstNode> AstId<N> {
+    pub(crate) fn file_id(&self) -> HirFileId {
+        self.file_id
+    }
+
+    pub(crate) fn to_node(&self, db: &impl DefDatabase) -> TreeArc<N> {
+        let syntax_node = db.ast_id_to_node(self.file_id, self.file_ast_id.raw);
+        N::cast(&syntax_node).unwrap().to_owned()
+    }
+}
+
+/// `AstId` points to an AST node in a specific file.
+#[derive(Debug)]
+pub(crate) struct FileAstId<N: AstNode> {
+    raw: ErasedFileAstId,
+    _ty: PhantomData<N>,
+}
+
+impl<N: AstNode> Clone for FileAstId<N> {
+    fn clone(&self) -> FileAstId<N> {
+        *self
+    }
+}
+impl<N: AstNode> Copy for FileAstId<N> {}
+
+impl<N: AstNode> PartialEq for FileAstId<N> {
+    fn eq(&self, other: &Self) -> bool {
+        self.raw == other.raw
+    }
+}
+impl<N: AstNode> Eq for FileAstId<N> {}
+impl<N: AstNode> Hash for FileAstId<N> {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.raw.hash(hasher);
+    }
+}
+
+impl<N: AstNode> FileAstId<N> {
+    pub(crate) fn with_file_id(self, file_id: HirFileId) -> AstId<N> {
+        AstId { file_id, file_ast_id: self }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ErasedFileAstId(RawId);
+impl_arena_id!(ErasedFileAstId);
+
+/// Maps items' `SyntaxNode`s to `ErasedFileAstId`s and back.
+#[derive(Debug, PartialEq, Eq)]
+pub struct AstIdMap {
+    arena: Arena<ErasedFileAstId, SyntaxNodePtr>,
+}
+
+impl AstIdMap {
+    pub(crate) fn ast_id_map_query(db: &impl DefDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
+        let source_file = db.hir_parse(file_id);
+        Arc::new(AstIdMap::from_source_file(&source_file))
+    }
+
+    pub(crate) fn file_item_query(
+        db: &impl DefDatabase,
+        file_id: HirFileId,
+        ast_id: ErasedFileAstId,
+    ) -> TreeArc<SyntaxNode> {
+        let source_file = db.hir_parse(file_id);
+        db.ast_id_map(file_id).arena[ast_id].to_node(&source_file).to_owned()
+    }
+
+    pub(crate) fn ast_id<N: AstNode>(&self, item: &N) -> FileAstId<N> {
+        let ptr = SyntaxNodePtr::new(item.syntax());
+        let raw = match self.arena.iter().find(|(_id, i)| **i == ptr) {
+            Some((it, _)) => it,
+            None => panic!(
+                "Can't find {:?} in AstIdMap:\n{:?}",
+                item.syntax(),
+                self.arena.iter().map(|(_id, i)| i).collect::<Vec<_>>(),
+            ),
+        };
+
+        FileAstId { raw, _ty: PhantomData }
+    }
+
+    fn from_source_file(source_file: &SourceFile) -> AstIdMap {
+        let mut res = AstIdMap { arena: Arena::default() };
+        // By walking the tree in bread-first order we make sure that parents
+        // get lower ids then children. That is, adding a new child does not
+        // change parent's id. This means that, say, adding a new function to a
+        // trait does not change ids of top-level items, which helps caching.
+        bfs(source_file.syntax(), |it| {
+            if let Some(module_item) = ast::ModuleItem::cast(it) {
+                res.alloc(module_item.syntax());
+            } else if let Some(macro_call) = ast::MacroCall::cast(it) {
+                res.alloc(macro_call.syntax());
+            }
+        });
+        res
+    }
+
+    fn alloc(&mut self, item: &SyntaxNode) -> ErasedFileAstId {
+        self.arena.alloc(SyntaxNodePtr::new(item))
+    }
+}
+
+/// Walks the subtree in bfs order, calling `f` for each node.
+fn bfs(node: &SyntaxNode, mut f: impl FnMut(&SyntaxNode)) {
+    let mut curr_layer = vec![node];
+    let mut next_layer = vec![];
+    while !curr_layer.is_empty() {
+        curr_layer.drain(..).for_each(|node| {
+            next_layer.extend(node.children());
+            f(node);
+        });
+        std::mem::swap(&mut curr_layer, &mut next_layer);
+    }
+}
diff --git a/crates/ra_hir/src/traits.rs b/crates/ra_hir/src/traits.rs
new file mode 100644
index 000000000..725bdd5cb
--- /dev/null
+++ b/crates/ra_hir/src/traits.rs
@@ -0,0 +1,52 @@
+//! HIR for trait definitions.
+
+use std::sync::Arc;
+
+use ra_syntax::ast::{self, NameOwner};
+
+use crate::{Function, Const, TypeAlias, Name, DefDatabase, Trait, ids::LocationCtx, name::AsName};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TraitData {
+    name: Option<Name>,
+    items: Vec<TraitItem>,
+}
+
+impl TraitData {
+    pub(crate) fn trait_data_query(db: &impl DefDatabase, tr: Trait) -> Arc<TraitData> {
+        let (file_id, node) = tr.source(db);
+        let name = node.name().map(|n| n.as_name());
+        let module = tr.module(db);
+        let ctx = LocationCtx::new(db, module, file_id);
+        let items = if let Some(item_list) = node.item_list() {
+            item_list
+                .impl_items()
+                .map(|item_node| match item_node.kind() {
+                    ast::ImplItemKind::FnDef(it) => Function { id: ctx.to_def(it) }.into(),
+                    ast::ImplItemKind::ConstDef(it) => Const { id: ctx.to_def(it) }.into(),
+                    ast::ImplItemKind::TypeAliasDef(it) => TypeAlias { id: ctx.to_def(it) }.into(),
+                })
+                .collect()
+        } else {
+            Vec::new()
+        };
+        Arc::new(TraitData { name, items })
+    }
+
+    pub(crate) fn name(&self) -> &Option<Name> {
+        &self.name
+    }
+
+    pub(crate) fn items(&self) -> &[TraitItem] {
+        &self.items
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum TraitItem {
+    Function(Function),
+    Const(Const),
+    TypeAlias(TypeAlias),
+    // Existential
+}
+impl_froms!(TraitItem: Function, Const, TypeAlias);
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 7d25ade47..d42c61e9d 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -14,7 +14,7 @@ pub(crate) mod display;
 use std::sync::Arc;
 use std::{fmt, mem};
 
-use crate::{Name, AdtDef, type_ref::Mutability, db::HirDatabase};
+use crate::{Name, AdtDef, type_ref::Mutability, db::HirDatabase, Trait};
 
 pub(crate) use lower::{TypableDef, CallableDef, type_for_def, type_for_field, callable_item_sig};
 pub(crate) use infer::{infer, InferenceResult, InferTy};
@@ -91,7 +91,7 @@ pub enum TypeCtor {
 /// A nominal type with (maybe 0) type parameters. This might be a primitive
 /// type like `bool`, a struct, tuple, function pointer, reference or
 /// several other things.
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct ApplicationTy {
     pub ctor: TypeCtor,
     pub parameters: Substs,
@@ -103,7 +103,7 @@ pub struct ApplicationTy {
 /// the same thing (but in a different way).
 ///
 /// This should be cheap to clone.
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub enum Ty {
     /// A nominal type with (maybe 0) type parameters. This might be a primitive
     /// type like `bool`, a struct, tuple, function pointer, reference or
@@ -132,7 +132,7 @@ pub enum Ty {
 }
 
 /// A list of substitutions for generic parameters.
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct Substs(Arc<[Ty]>);
 
 impl Substs {
@@ -169,6 +169,21 @@ impl Substs {
     }
 }
 
+/// A trait with type parameters. This includes the `Self`, so this represents a concrete type implementing the trait.
+/// Name to be bikeshedded: TraitBound? TraitImplements?
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct TraitRef {
+    /// FIXME name?
+    trait_: Trait,
+    substs: Substs,
+}
+
+impl TraitRef {
+    pub fn self_ty(&self) -> &Ty {
+        &self.substs.0[0]
+    }
+}
+
 /// A function signature as seen by type inference: Several parameter types and
 /// one return type.
 #[derive(Clone, PartialEq, Eq, Debug)]
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index cff7e7481..573115321 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -36,7 +36,9 @@ use crate::{
     path::{GenericArgs, GenericArg},
     adt::VariantDef,
     resolve::{Resolver, Resolution},
-    nameres::Namespace
+    nameres::Namespace,
+    ty::infer::diagnostics::InferenceDiagnostic,
+    diagnostics::DiagnosticSink,
 };
 use super::{Ty, TypableDef, Substs, primitive, op, FnSig, ApplicationTy, TypeCtor};
 
@@ -96,6 +98,7 @@ pub struct InferenceResult {
     field_resolutions: FxHashMap<ExprId, StructField>,
     /// For each associated item record what it resolves to
     assoc_resolutions: FxHashMap<ExprOrPatId, ImplItem>,
+    diagnostics: Vec<InferenceDiagnostic>,
     pub(super) type_of_expr: ArenaMap<ExprId, Ty>,
     pub(super) type_of_pat: ArenaMap<PatId, Ty>,
 }
@@ -113,6 +116,14 @@ impl InferenceResult {
     pub fn assoc_resolutions_for_pat(&self, id: PatId) -> Option<ImplItem> {
         self.assoc_resolutions.get(&id.into()).map(|it| *it)
     }
+    pub(crate) fn add_diagnostics(
+        &self,
+        db: &impl HirDatabase,
+        owner: Function,
+        sink: &mut DiagnosticSink,
+    ) {
+        self.diagnostics.iter().for_each(|it| it.add_to(db, owner, sink))
+    }
 }
 
 impl Index<ExprId> for InferenceResult {
@@ -143,6 +154,7 @@ struct InferenceContext<'a, D: HirDatabase> {
     assoc_resolutions: FxHashMap<ExprOrPatId, ImplItem>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
+    diagnostics: Vec<InferenceDiagnostic>,
     /// The return type of the function being inferred.
     return_ty: Ty,
 }
@@ -155,6 +167,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             assoc_resolutions: FxHashMap::default(),
             type_of_expr: ArenaMap::default(),
             type_of_pat: ArenaMap::default(),
+            diagnostics: Vec::default(),
             var_unification_table: InPlaceUnificationTable::new(),
             return_ty: Ty::Unknown, // set in collect_fn_signature
             db,
@@ -181,6 +194,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             assoc_resolutions: self.assoc_resolutions,
             type_of_expr: expr_types,
             type_of_pat: pat_types,
+            diagnostics: self.diagnostics,
         }
     }
 
@@ -807,7 +821,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             }
             Expr::MethodCall { receiver, args, method_name, generic_args } => {
                 let receiver_ty = self.infer_expr(*receiver, &Expectation::none());
-                let resolved = receiver_ty.clone().lookup_method(self.db, method_name);
+                let resolved =
+                    receiver_ty.clone().lookup_method(self.db, method_name, &self.resolver);
                 let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
                     Some((ty, func)) => {
                         self.write_method_resolution(tgt_expr, func);
@@ -915,9 +930,18 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::StructLit { path, fields, spread } => {
                 let (ty, def_id) = self.resolve_variant(path.as_ref());
                 let substs = ty.substs().unwrap_or_else(Substs::empty);
-                for field in fields {
+                for (field_idx, field) in fields.into_iter().enumerate() {
                     let field_ty = def_id
-                        .and_then(|it| it.field(self.db, &field.name))
+                        .and_then(|it| match it.field(self.db, &field.name) {
+                            Some(field) => Some(field),
+                            None => {
+                                self.diagnostics.push(InferenceDiagnostic::NoSuchField {
+                                    expr: tgt_expr,
+                                    field: field_idx,
+                                });
+                                None
+                            }
+                        })
                         .map_or(Ty::Unknown, |field| field.ty(self.db))
                         .subst(&substs);
                     self.infer_expr(field.expr, &Expectation::has_type(field_ty));
@@ -1244,3 +1268,29 @@ impl Expectation {
         Expectation { ty: Ty::Unknown }
     }
 }
+
+mod diagnostics {
+    use crate::{expr::ExprId, diagnostics::{DiagnosticSink, NoSuchField}, HirDatabase, Function};
+
+    #[derive(Debug, PartialEq, Eq, Clone)]
+    pub(super) enum InferenceDiagnostic {
+        NoSuchField { expr: ExprId, field: usize },
+    }
+
+    impl InferenceDiagnostic {
+        pub(super) fn add_to(
+            &self,
+            db: &impl HirDatabase,
+            owner: Function,
+            sink: &mut DiagnosticSink,
+        ) {
+            match self {
+                InferenceDiagnostic::NoSuchField { expr, field } => {
+                    let (file, _) = owner.source(db);
+                    let field = owner.body_source_map(db).field_syntax(*expr, *field);
+                    sink.push(NoSuchField { file, field })
+                }
+            }
+        }
+    }
+}
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index b1684acf9..3ac8dc46b 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -8,12 +8,12 @@ use rustc_hash::FxHashMap;
 
 use crate::{
     HirDatabase, Module, Crate, Name, Function, Trait,
-    ids::TraitId,
     impl_block::{ImplId, ImplBlock, ImplItem},
     ty::{Ty, TypeCtor},
-    nameres::CrateModuleId,
+    nameres::CrateModuleId, resolve::Resolver, traits::TraitItem
 
 };
+use super::{ TraitRef, Substs};
 
 /// This is used as a key for indexing impls.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
@@ -38,7 +38,7 @@ pub struct CrateImplBlocks {
     /// To make sense of the CrateModuleIds, we need the source root.
     krate: Crate,
     impls: FxHashMap<TyFingerprint, Vec<(CrateModuleId, ImplId)>>,
-    impls_by_trait: FxHashMap<TraitId, Vec<(CrateModuleId, ImplId)>>,
+    impls_by_trait: FxHashMap<Trait, Vec<(CrateModuleId, ImplId)>>,
 }
 
 impl CrateImplBlocks {
@@ -56,8 +56,7 @@ impl CrateImplBlocks {
         &'a self,
         tr: &Trait,
     ) -> impl Iterator<Item = ImplBlock> + 'a {
-        let id = tr.id;
-        self.impls_by_trait.get(&id).into_iter().flat_map(|i| i.iter()).map(
+        self.impls_by_trait.get(&tr).into_iter().flat_map(|i| i.iter()).map(
             move |(module_id, impl_id)| {
                 let module = Module { krate: self.krate, module_id: *module_id };
                 ImplBlock::from_id(module, *impl_id)
@@ -73,18 +72,18 @@ impl CrateImplBlocks {
 
             let target_ty = impl_block.target_ty(db);
 
-            if let Some(target_ty_fp) = TyFingerprint::for_impl(&target_ty) {
-                self.impls
-                    .entry(target_ty_fp)
-                    .or_insert_with(Vec::new)
-                    .push((module.module_id, impl_id));
-            }
-
             if let Some(tr) = impl_block.target_trait(db) {
                 self.impls_by_trait
-                    .entry(tr.id)
+                    .entry(tr)
                     .or_insert_with(Vec::new)
                     .push((module.module_id, impl_id));
+            } else {
+                if let Some(target_ty_fp) = TyFingerprint::for_impl(&target_ty) {
+                    self.impls
+                        .entry(target_ty_fp)
+                        .or_insert_with(Vec::new)
+                        .push((module.module_id, impl_id));
+                }
             }
         }
 
@@ -109,6 +108,20 @@ impl CrateImplBlocks {
     }
 }
 
+/// Rudimentary check whether an impl exists for a given type and trait; this
+/// will actually be done by chalk.
+pub(crate) fn implements(db: &impl HirDatabase, trait_ref: TraitRef) -> bool {
+    // FIXME use all trait impls in the whole crate graph
+    let krate = trait_ref.trait_.module(db).krate(db);
+    let krate = match krate {
+        Some(krate) => krate,
+        None => return false,
+    };
+    let crate_impl_blocks = db.impls_in_crate(krate);
+    let mut impl_blocks = crate_impl_blocks.lookup_impl_blocks_for_trait(&trait_ref.trait_);
+    impl_blocks.any(|impl_block| &impl_block.target_ty(db) == trait_ref.self_ty())
+}
+
 fn def_crate(db: &impl HirDatabase, ty: &Ty) -> Option<Crate> {
     match ty {
         Ty::Apply(a_ty) => match a_ty.ctor {
@@ -120,20 +133,64 @@ fn def_crate(db: &impl HirDatabase, ty: &Ty) -> Option<Crate> {
 }
 
 impl Ty {
-    // FIXME: cache this as a query?
-    // - if so, what signature? (TyFingerprint, Name)?
-    // - or maybe cache all names and def_ids of methods per fingerprint?
     /// Look up the method with the given name, returning the actual autoderefed
     /// receiver type (but without autoref applied yet).
-    pub fn lookup_method(self, db: &impl HirDatabase, name: &Name) -> Option<(Ty, Function)> {
-        self.iterate_methods(db, |ty, f| {
+    pub fn lookup_method(
+        self,
+        db: &impl HirDatabase,
+        name: &Name,
+        resolver: &Resolver,
+    ) -> Option<(Ty, Function)> {
+        // FIXME: trait methods should be used before autoderefs
+        let inherent_method = self.clone().iterate_methods(db, |ty, f| {
             let sig = f.signature(db);
             if sig.name() == name && sig.has_self_param() {
                 Some((ty.clone(), f))
             } else {
                 None
             }
-        })
+        });
+        inherent_method.or_else(|| self.lookup_trait_method(db, name, resolver))
+    }
+
+    fn lookup_trait_method(
+        self,
+        db: &impl HirDatabase,
+        name: &Name,
+        resolver: &Resolver,
+    ) -> Option<(Ty, Function)> {
+        let mut candidates = Vec::new();
+        for t in resolver.traits_in_scope() {
+            let data = t.trait_data(db);
+            for item in data.items() {
+                match item {
+                    &TraitItem::Function(m) => {
+                        let sig = m.signature(db);
+                        if sig.name() == name && sig.has_self_param() {
+                            candidates.push((t, m));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
+        // FIXME:
+        //  - we might not actually be able to determine fully that the type
+        //    implements the trait here; it's enough if we (well, Chalk) determine
+        //    that it's possible.
+        //  - when the trait method is picked, we need to register an
+        //    'obligation' somewhere so that we later check that it's really
+        //    implemented
+        //  - both points go for additional requirements from where clauses as
+        //    well (in fact, the 'implements' condition could just be considered a
+        //    'where Self: Trait' clause)
+        candidates.retain(|(t, _m)| {
+            let trait_ref = TraitRef { trait_: *t, substs: Substs::single(self.clone()) };
+            db.implements(trait_ref)
+        });
+        // FIXME if there's multiple candidates here, that's an ambiguity error
+        let (_chosen_trait, chosen_method) = candidates.first()?;
+        Some((self.clone(), *chosen_method))
     }
 
     // This would be nicer if it just returned an iterator, but that runs into
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 5d8ad4aa7..655f3c522 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -1272,8 +1272,8 @@ fn test() {
 [241; 252) 'Struct::FOO': u32
 [262; 263) 'y': u32
 [266; 275) 'Enum::BAR': u32
-[285; 286) 'z': u32
-[289; 302) 'TraitTest::ID': u32"###
+[285; 286) 'z': {unknown}
+[289; 302) 'TraitTest::ID': {unknown}"###
     );
 }
 
@@ -1918,9 +1918,9 @@ fn test() {
 [110; 114) 'self': &{unknown}
 [170; 228) '{     ...i128 }': ()
 [176; 178) 'S1': S1
-[176; 187) 'S1.method()': {unknown}
+[176; 187) 'S1.method()': u32
 [203; 205) 'S2': S2
-[203; 214) 'S2.method()': {unknown}"###
+[203; 214) 'S2.method()': i128"###
     );
 }
 
@@ -1964,10 +1964,10 @@ mod bar_test {
 [169; 173) 'self': &{unknown}
 [300; 337) '{     ...     }': ()
 [310; 311) 'S': S
-[310; 320) 'S.method()': {unknown}
+[310; 320) 'S.method()': u32
 [416; 454) '{     ...     }': ()
 [426; 427) 'S': S
-[426; 436) 'S.method()': {unknown}"###
+[426; 436) 'S.method()': i128"###
     );
 }
 
@@ -2319,3 +2319,27 @@ fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
         assert!(!format!("{:?}", events).contains("infer"), "{:#?}", events)
     }
 }
+
+#[test]
+fn no_such_field_diagnostics() {
+    let diagnostics = MockDatabase::with_files(
+        r"
+        //- /lib.rs
+        struct S { foo: i32, bar: () }
+        impl S {
+            fn new() -> S {
+                S {
+                    foo: 92,
+                    baz: 62,
+                }
+            }
+        }
+        ",
+    )
+    .diagnostics();
+
+    assert_snapshot_matches!(diagnostics, @r###"
+"baz: 62": no such field
+"###
+    );
+}