1 files changed, 954 insertions, 0 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
new file mode 100644
index 000000000..49030ce67
--- /dev/null
+++ b/crates/ra_hir/src/code_model.rs
@@ -0,0 +1,954 @@
+use std::sync::Arc;
+
+use ra_db::{CrateId, SourceRootId, Edition, FileId};
+use ra_syntax::{ast::{self, NameOwner, TypeAscriptionOwner}, TreeArc};
+
+use crate::{
+    Name, AsName, AstId, Ty, HirFileId, Either,
+    HirDatabase, DefDatabase,
+    type_ref::TypeRef,
+    nameres::{ModuleScope, Namespace, ImportId, CrateModuleId},
+    expr::{Body, BodySourceMap, validation::ExprValidator},
+    ty::{TraitRef, InferenceResult},
+    adt::{EnumVariantId, StructFieldId, VariantDef},
+    generics::HasGenericParams,
+    docs::{Documentation, Docs, docs_from_ast},
+    ids::{FunctionId, StructId, EnumId, AstItemDef, ConstId, StaticId, TraitId, TypeAliasId},
+    impl_block::ImplBlock,
+    resolve::Resolver,
+    diagnostics::{DiagnosticSink},
+    traits::{TraitItem, TraitData},
+    type_ref::Mutability,
+};
+
+/// hir::Crate describes a single crate. It's the main interface with which
+/// a crate's dependencies interact. Mostly, it should be just a proxy for the
+/// root module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Crate {
+    pub(crate) crate_id: CrateId,
+}
+
+#[derive(Debug)]
+pub struct CrateDependency {
+    pub krate: Crate,
+    pub name: Name,
+}
+
+impl Crate {
+    pub fn crate_id(self) -> CrateId {
+        self.crate_id
+    }
+
+    pub fn dependencies(self, db: &impl DefDatabase) -> Vec<CrateDependency> {
+        db.crate_graph()
+            .dependencies(self.crate_id)
+            .map(|dep| {
+                let krate = Crate { crate_id: dep.crate_id() };
+                let name = dep.as_name();
+                CrateDependency { krate, name }
+            })
+            .collect()
+    }
+
+    pub fn root_module(self, db: &impl DefDatabase) -> Option<Module> {
+        let module_id = db.crate_def_map(self).root();
+        let module = Module { krate: self, module_id };
+        Some(module)
+    }
+
+    pub fn edition(self, db: &impl DefDatabase) -> Edition {
+        let crate_graph = db.crate_graph();
+        crate_graph.edition(self.crate_id)
+    }
+
+    // FIXME: should this be in source_binder?
+    pub fn source_root_crates(db: &impl DefDatabase, source_root: SourceRootId) -> Vec<Crate> {
+        let crate_ids = db.source_root_crates(source_root);
+        crate_ids.iter().map(|&crate_id| Crate { crate_id }).collect()
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Module {
+    pub(crate) krate: Crate,
+    pub(crate) module_id: CrateModuleId,
+}
+
+/// The defs which can be visible in the module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ModuleDef {
+    Module(Module),
+    Function(Function),
+    Struct(Struct),
+    Union(Union),
+    Enum(Enum),
+    // Can't be directly declared, but can be imported.
+    EnumVariant(EnumVariant),
+    Const(Const),
+    Static(Static),
+    Trait(Trait),
+    TypeAlias(TypeAlias),
+}
+impl_froms!(
+    ModuleDef: Module,
+    Function,
+    Struct,
+    Union,
+    Enum,
+    EnumVariant,
+    Const,
+    Static,
+    Trait,
+    TypeAlias
+);
+
+pub enum ModuleSource {
+    SourceFile(TreeArc<ast::SourceFile>),
+    Module(TreeArc<ast::Module>),
+}
+
+impl ModuleSource {
+    pub(crate) fn new(
+        db: &impl DefDatabase,
+        file_id: Option<FileId>,
+        decl_id: Option<AstId<ast::Module>>,
+    ) -> ModuleSource {
+        match (file_id, decl_id) {
+            (Some(file_id), _) => {
+                let source_file = db.parse(file_id);
+                ModuleSource::SourceFile(source_file)
+            }
+            (None, Some(item_id)) => {
+                let module = item_id.to_node(db);
+                assert!(module.item_list().is_some(), "expected inline module");
+                ModuleSource::Module(module.to_owned())
+            }
+            (None, None) => panic!(),
+        }
+    }
+}
+
+impl Module {
+    /// Name of this module.
+    pub fn name(self, db: &impl HirDatabase) -> Option<Name> {
+        let def_map = db.crate_def_map(self.krate);
+        let parent = def_map[self.module_id].parent?;
+        def_map[parent].children.iter().find_map(|(name, module_id)| {
+            if *module_id == self.module_id {
+                Some(name.clone())
+            } else {
+                None
+            }
+        })
+    }
+
+    /// 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) -> (HirFileId, ModuleSource) {
+        let def_map = db.crate_def_map(self.krate);
+        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());
+        (file_id, module_source)
+    }
+
+    /// Returns a node which declares this module, either a `mod foo;` or a `mod foo {}`.
+    /// `None` for the crate root.
+    pub fn declaration_source(
+        self,
+        db: &impl HirDatabase,
+    ) -> Option<(HirFileId, TreeArc<ast::Module>)> {
+        let def_map = db.crate_def_map(self.krate);
+        let decl = def_map[self.module_id].declaration?;
+        let ast = decl.to_node(db);
+        Some((decl.file_id(), ast))
+    }
+
+    /// Returns the syntax of the last path segment corresponding to this import
+    pub fn import_source(
+        self,
+        db: &impl HirDatabase,
+        import: ImportId,
+    ) -> Either<TreeArc<ast::UseTree>, TreeArc<ast::ExternCrateItem>> {
+        let (file_id, source) = self.definition_source(db);
+        let (_, source_map) = db.raw_items_with_source_map(file_id);
+        source_map.get(&source, import)
+    }
+
+    /// Returns the crate this module is part of.
+    pub fn krate(self, _db: &impl DefDatabase) -> Option<Crate> {
+        Some(self.krate)
+    }
+
+    /// Topmost parent of this module. Every module has a `crate_root`, but some
+    /// might be missing `krate`. This can happen if a module's file is not included
+    /// in the module tree of any target in `Cargo.toml`.
+    pub fn crate_root(self, db: &impl DefDatabase) -> Module {
+        let def_map = db.crate_def_map(self.krate);
+        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 child_id = def_map[self.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 children = def_map[self.module_id]
+            .children
+            .iter()
+            .map(|(_, module_id)| self.with_module_id(*module_id))
+            .collect::<Vec<_>>();
+        children.into_iter()
+    }
+
+    /// Finds a parent module.
+    pub fn parent(self, db: &impl DefDatabase) -> Option<Module> {
+        let def_map = db.crate_def_map(self.krate);
+        let parent_id = def_map[self.module_id].parent?;
+        Some(self.with_module_id(parent_id))
+    }
+
+    pub fn path_to_root(self, db: &impl HirDatabase) -> Vec<Module> {
+        let mut res = vec![self.clone()];
+        let mut curr = self.clone();
+        while let Some(next) = curr.parent(db) {
+            res.push(next.clone());
+            curr = next
+        }
+        res
+    }
+
+    /// Returns a `ModuleScope`: a set of items, visible in this module.
+    pub fn scope(self, db: &impl HirDatabase) -> ModuleScope {
+        db.crate_def_map(self.krate)[self.module_id].scope.clone()
+    }
+
+    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(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
+        let def_map = db.crate_def_map(self.krate);
+        Resolver::default().push_module_scope(def_map, self.module_id)
+    }
+
+    pub fn declarations(self, db: &impl DefDatabase) -> Vec<ModuleDef> {
+        let def_map = db.crate_def_map(self.krate);
+        def_map[self.module_id]
+            .scope
+            .entries()
+            .filter_map(|(_name, res)| if res.import.is_none() { Some(res.def) } else { None })
+            .flat_map(|per_ns| {
+                per_ns.take_types().into_iter().chain(per_ns.take_values().into_iter())
+            })
+            .collect()
+    }
+
+    pub fn impl_blocks(self, db: &impl HirDatabase) -> Vec<ImplBlock> {
+        let module_impl_blocks = db.impls_in_module(self);
+        module_impl_blocks
+            .impls
+            .iter()
+            .map(|(impl_id, _)| ImplBlock::from_id(self, impl_id))
+            .collect()
+    }
+
+    fn with_module_id(&self, module_id: CrateModuleId) -> Module {
+        Module { module_id, krate: self.krate }
+    }
+}
+
+impl Docs for Module {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        self.declaration_source(db).and_then(|it| docs_from_ast(&*it.1))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct StructField {
+    pub(crate) parent: VariantDef,
+    pub(crate) id: StructFieldId,
+}
+
+#[derive(Debug)]
+pub enum FieldSource {
+    Named(TreeArc<ast::NamedFieldDef>),
+    Pos(TreeArc<ast::PosFieldDef>),
+}
+
+impl StructField {
+    pub fn name(&self, db: &impl HirDatabase) -> Name {
+        self.parent.variant_data(db).fields().unwrap()[self.id].name.clone()
+    }
+
+    pub fn source(&self, db: &impl DefDatabase) -> (HirFileId, FieldSource) {
+        self.source_impl(db)
+    }
+
+    pub fn ty(&self, db: &impl HirDatabase) -> Ty {
+        db.type_for_field(*self)
+    }
+
+    pub fn parent_def(&self, _db: &impl HirDatabase) -> VariantDef {
+        self.parent
+    }
+}
+
+impl Docs for StructField {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        match self.source(db).1 {
+            FieldSource::Named(named) => docs_from_ast(&*named),
+            FieldSource::Pos(..) => return None,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Struct {
+    pub(crate) id: StructId,
+}
+
+impl Struct {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    pub fn name(self, db: &impl HirDatabase) -> Option<Name> {
+        db.struct_data(self).name.clone()
+    }
+
+    pub fn fields(self, db: &impl HirDatabase) -> Vec<StructField> {
+        db.struct_data(self)
+            .variant_data
+            .fields()
+            .into_iter()
+            .flat_map(|it| it.iter())
+            .map(|(id, _)| StructField { parent: self.into(), id })
+            .collect()
+    }
+
+    pub fn field(self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
+        db.struct_data(self)
+            .variant_data
+            .fields()
+            .into_iter()
+            .flat_map(|it| it.iter())
+            .find(|(_id, data)| data.name == *name)
+            .map(|(id, _)| StructField { parent: self.into(), id })
+    }
+
+    pub fn ty(self, db: &impl HirDatabase) -> Ty {
+        db.type_for_def(self.into(), Namespace::Types)
+    }
+
+    pub fn constructor_ty(self, db: &impl HirDatabase) -> Ty {
+        db.type_for_def(self.into(), Namespace::Values)
+    }
+
+    // FIXME move to a more general type
+    /// Builds a resolver for type references inside this struct.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self.module(db).resolver(db);
+        // ...and add generic params, if present
+        let p = self.generic_params(db);
+        let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
+        r
+    }
+}
+
+impl Docs for Struct {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Union {
+    pub(crate) id: StructId,
+}
+
+impl Union {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::StructDef>) {
+        self.id.source(db)
+    }
+
+    pub fn name(self, db: &impl HirDatabase) -> Option<Name> {
+        db.struct_data(Struct { id: self.id }).name.clone()
+    }
+
+    pub fn module(self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    // FIXME move to a more general type
+    /// Builds a resolver for type references inside this union.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self.module(db).resolver(db);
+        // ...and add generic params, if present
+        let p = self.generic_params(db);
+        let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
+        r
+    }
+}
+
+impl Docs for Union {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Enum {
+    pub(crate) id: EnumId,
+}
+
+impl Enum {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::EnumDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl HirDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    pub fn name(self, db: &impl HirDatabase) -> Option<Name> {
+        db.enum_data(self).name.clone()
+    }
+
+    pub fn variants(self, db: &impl DefDatabase) -> Vec<EnumVariant> {
+        db.enum_data(self).variants.iter().map(|(id, _)| EnumVariant { parent: self, id }).collect()
+    }
+
+    pub fn variant(self, db: &impl DefDatabase, name: &Name) -> Option<EnumVariant> {
+        db.enum_data(self)
+            .variants
+            .iter()
+            .find(|(_id, data)| data.name.as_ref() == Some(name))
+            .map(|(id, _)| EnumVariant { parent: self, id })
+    }
+
+    pub fn ty(self, db: &impl HirDatabase) -> Ty {
+        db.type_for_def(self.into(), Namespace::Types)
+    }
+
+    // FIXME: move to a more general type
+    /// Builds a resolver for type references inside this struct.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self.module(db).resolver(db);
+        // ...and add generic params, if present
+        let p = self.generic_params(db);
+        let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
+        r
+    }
+}
+
+impl Docs for Enum {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EnumVariant {
+    pub(crate) parent: Enum,
+    pub(crate) id: EnumVariantId,
+}
+
+impl EnumVariant {
+    pub fn source(&self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::EnumVariant>) {
+        self.source_impl(db)
+    }
+    pub fn module(&self, db: &impl HirDatabase) -> Module {
+        self.parent.module(db)
+    }
+    pub fn parent_enum(&self, _db: &impl DefDatabase) -> Enum {
+        self.parent
+    }
+
+    pub fn name(&self, db: &impl DefDatabase) -> Option<Name> {
+        db.enum_data(self.parent).variants[self.id].name.clone()
+    }
+
+    pub fn fields(&self, db: &impl HirDatabase) -> Vec<StructField> {
+        self.variant_data(db)
+            .fields()
+            .into_iter()
+            .flat_map(|it| it.iter())
+            .map(|(id, _)| StructField { parent: (*self).into(), id })
+            .collect()
+    }
+
+    pub fn field(&self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
+        self.variant_data(db)
+            .fields()
+            .into_iter()
+            .flat_map(|it| it.iter())
+            .find(|(_id, data)| data.name == *name)
+            .map(|(id, _)| StructField { parent: (*self).into(), id })
+    }
+}
+
+impl Docs for EnumVariant {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+/// The defs which have a body.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum DefWithBody {
+    Function(Function),
+    Static(Static),
+    Const(Const),
+}
+
+impl_froms!(DefWithBody: Function, Const, Static);
+
+impl DefWithBody {
+    pub fn infer(self, db: &impl HirDatabase) -> Arc<InferenceResult> {
+        db.infer(self)
+    }
+
+    pub fn body(self, db: &impl HirDatabase) -> Arc<Body> {
+        db.body_hir(self)
+    }
+
+    pub fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap> {
+        db.body_with_source_map(self).1
+    }
+
+    /// Builds a resolver for code inside this item.
+    pub(crate) fn resolver(&self, db: &impl HirDatabase) -> Resolver {
+        match *self {
+            DefWithBody::Const(ref c) => c.resolver(db),
+            DefWithBody::Function(ref f) => f.resolver(db),
+            DefWithBody::Static(ref s) => s.resolver(db),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Function {
+    pub(crate) id: FunctionId,
+}
+
+/// The declared signature of a function.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FnSignature {
+    pub(crate) name: Name,
+    pub(crate) params: Vec<TypeRef>,
+    pub(crate) ret_type: TypeRef,
+    /// True if the first param is `self`. This is relevant to decide whether this
+    /// can be called as a method.
+    pub(crate) has_self_param: bool,
+}
+
+impl FnSignature {
+    pub(crate) fn fn_signature_query(db: &impl DefDatabase, func: Function) -> Arc<FnSignature> {
+        let (_, node) = func.source(db);
+        let name = node.name().map(|n| n.as_name()).unwrap_or_else(Name::missing);
+        let mut params = Vec::new();
+        let mut has_self_param = false;
+        if let Some(param_list) = node.param_list() {
+            if let Some(self_param) = param_list.self_param() {
+                let self_type = if let Some(type_ref) = self_param.ascribed_type() {
+                    TypeRef::from_ast(type_ref)
+                } else {
+                    let self_type = TypeRef::Path(Name::self_type().into());
+                    match self_param.kind() {
+                        ast::SelfParamKind::Owned => self_type,
+                        ast::SelfParamKind::Ref => {
+                            TypeRef::Reference(Box::new(self_type), Mutability::Shared)
+                        }
+                        ast::SelfParamKind::MutRef => {
+                            TypeRef::Reference(Box::new(self_type), Mutability::Mut)
+                        }
+                    }
+                };
+                params.push(self_type);
+                has_self_param = true;
+            }
+            for param in param_list.params() {
+                let type_ref = TypeRef::from_ast_opt(param.ascribed_type());
+                params.push(type_ref);
+            }
+        }
+        let ret_type = if let Some(type_ref) = node.ret_type().and_then(|rt| rt.type_ref()) {
+            TypeRef::from_ast(type_ref)
+        } else {
+            TypeRef::unit()
+        };
+
+        let sig = FnSignature { name, params, ret_type, has_self_param };
+        Arc::new(sig)
+    }
+    pub fn name(&self) -> &Name {
+        &self.name
+    }
+
+    pub fn params(&self) -> &[TypeRef] {
+        &self.params
+    }
+
+    pub fn ret_type(&self) -> &TypeRef {
+        &self.ret_type
+    }
+
+    /// True if the first arg is `self`. This is relevant to decide whether this
+    /// can be called as a method.
+    pub fn has_self_param(&self) -> bool {
+        self.has_self_param
+    }
+}
+
+impl Function {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::FnDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl DefDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    pub fn name(self, db: &impl HirDatabase) -> Name {
+        self.signature(db).name.clone()
+    }
+
+    pub(crate) fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap> {
+        db.body_with_source_map(self.into()).1
+    }
+
+    pub fn body(self, db: &impl HirDatabase) -> Arc<Body> {
+        db.body_hir(self.into())
+    }
+
+    pub fn ty(self, db: &impl HirDatabase) -> Ty {
+        db.type_for_def(self.into(), Namespace::Values)
+    }
+
+    pub fn signature(self, db: &impl HirDatabase) -> Arc<FnSignature> {
+        db.fn_signature(self)
+    }
+
+    pub fn infer(self, db: &impl HirDatabase) -> Arc<InferenceResult> {
+        db.infer(self.into())
+    }
+
+    /// The containing impl block, if this is a method.
+    pub fn impl_block(self, db: &impl DefDatabase) -> Option<ImplBlock> {
+        let module_impls = db.impls_in_module(self.module(db));
+        ImplBlock::containing(module_impls, self.into())
+    }
+
+    /// The containing trait, if this is a trait method definition.
+    pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
+        db.trait_items_index(self.module(db)).get_parent_trait(self.into())
+    }
+
+    pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
+        if let Some(impl_block) = self.impl_block(db) {
+            Some(impl_block.into())
+        } else if let Some(trait_) = self.parent_trait(db) {
+            Some(trait_.into())
+        } else {
+            None
+        }
+    }
+
+    // FIXME: move to a more general type for 'body-having' items
+    /// Builds a resolver for code inside this item.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self.container(db).map_or_else(|| self.module(db).resolver(db), |c| c.resolver(db));
+        // ...and add generic params, if present
+        let p = self.generic_params(db);
+        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) {
+        let infer = self.infer(db);
+        infer.add_diagnostics(db, self, sink);
+        let mut validator = ExprValidator::new(self, infer, sink);
+        validator.validate_body(db);
+    }
+}
+
+impl Docs for Function {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Const {
+    pub(crate) id: ConstId,
+}
+
+impl Const {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::ConstDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl DefDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    pub fn signature(self, db: &impl HirDatabase) -> Arc<ConstSignature> {
+        db.const_signature(self)
+    }
+
+    pub fn infer(self, db: &impl HirDatabase) -> Arc<InferenceResult> {
+        db.infer(self.into())
+    }
+
+    /// The containing impl block, if this is a method.
+    pub fn impl_block(self, db: &impl DefDatabase) -> Option<ImplBlock> {
+        let module_impls = db.impls_in_module(self.module(db));
+        ImplBlock::containing(module_impls, self.into())
+    }
+
+    // FIXME: move to a more general type for 'body-having' items
+    /// Builds a resolver for code inside this item.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self
+            .impl_block(db)
+            .map(|ib| ib.resolver(db))
+            .unwrap_or_else(|| self.module(db).resolver(db));
+        r
+    }
+}
+
+impl Docs for Const {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+/// The declared signature of a const.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ConstSignature {
+    pub(crate) name: Name,
+    pub(crate) type_ref: TypeRef,
+}
+
+impl ConstSignature {
+    pub fn name(&self) -> &Name {
+        &self.name
+    }
+
+    pub fn type_ref(&self) -> &TypeRef {
+        &self.type_ref
+    }
+
+    pub(crate) fn const_signature_query(
+        db: &impl DefDatabase,
+        konst: Const,
+    ) -> Arc<ConstSignature> {
+        let (_, node) = konst.source(db);
+        const_signature_for(&*node)
+    }
+
+    pub(crate) fn static_signature_query(
+        db: &impl DefDatabase,
+        konst: Static,
+    ) -> Arc<ConstSignature> {
+        let (_, node) = konst.source(db);
+        const_signature_for(&*node)
+    }
+}
+
+fn const_signature_for<N: NameOwner + TypeAscriptionOwner>(node: &N) -> Arc<ConstSignature> {
+    let name = node.name().map(|n| n.as_name()).unwrap_or_else(Name::missing);
+    let type_ref = TypeRef::from_ast_opt(node.ascribed_type());
+    let sig = ConstSignature { name, type_ref };
+    Arc::new(sig)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Static {
+    pub(crate) id: StaticId,
+}
+
+impl Static {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::StaticDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl DefDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    pub fn signature(self, db: &impl HirDatabase) -> Arc<ConstSignature> {
+        db.static_signature(self)
+    }
+
+    /// Builds a resolver for code inside this item.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        self.module(db).resolver(db)
+    }
+
+    pub fn infer(self, db: &impl HirDatabase) -> Arc<InferenceResult> {
+        db.infer(self.into())
+    }
+}
+
+impl Docs for Static {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Trait {
+    pub(crate) id: TraitId,
+}
+
+impl Trait {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::TraitDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl DefDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    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)
+    }
+
+    pub fn trait_ref(self, db: &impl HirDatabase) -> TraitRef {
+        TraitRef::for_trait(db, self)
+    }
+
+    pub fn is_auto(self, db: &impl DefDatabase) -> bool {
+        self.trait_data(db).is_auto()
+    }
+
+    pub(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
+        let r = self.module(db).resolver(db);
+        // add generic params, if present
+        let p = self.generic_params(db);
+        let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
+        r
+    }
+}
+
+impl Docs for Trait {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeAlias {
+    pub(crate) id: TypeAliasId,
+}
+
+impl TypeAlias {
+    pub fn source(self, db: &impl DefDatabase) -> (HirFileId, TreeArc<ast::TypeAliasDef>) {
+        self.id.source(db)
+    }
+
+    pub fn module(self, db: &impl DefDatabase) -> Module {
+        self.id.module(db)
+    }
+
+    /// The containing impl block, if this is a method.
+    pub fn impl_block(self, db: &impl DefDatabase) -> Option<ImplBlock> {
+        let module_impls = db.impls_in_module(self.module(db));
+        ImplBlock::containing(module_impls, self.into())
+    }
+
+    /// The containing trait, if this is a trait method definition.
+    pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
+        db.trait_items_index(self.module(db)).get_parent_trait(self.into())
+    }
+
+    pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
+        if let Some(impl_block) = self.impl_block(db) {
+            Some(impl_block.into())
+        } else if let Some(trait_) = self.parent_trait(db) {
+            Some(trait_.into())
+        } else {
+            None
+        }
+    }
+
+    pub fn type_ref(self, db: &impl DefDatabase) -> Arc<TypeRef> {
+        db.type_alias_ref(self)
+    }
+
+    /// Builds a resolver for the type references in this type alias.
+    pub(crate) fn resolver(self, db: &impl HirDatabase) -> Resolver {
+        // take the outer scope...
+        let r = self
+            .impl_block(db)
+            .map(|ib| ib.resolver(db))
+            .unwrap_or_else(|| self.module(db).resolver(db));
+        // ...and add generic params, if present
+        let p = self.generic_params(db);
+        let r = if !p.params.is_empty() { r.push_generic_params_scope(p) } else { r };
+        r
+    }
+}
+
+impl Docs for TypeAlias {
+    fn docs(&self, db: &impl HirDatabase) -> Option<Documentation> {
+        docs_from_ast(&*self.source(db).1)
+    }
+}
+
+pub enum Container {
+    Trait(Trait),
+    ImplBlock(ImplBlock),
+}
+impl_froms!(Container: Trait, ImplBlock);
+
+impl Container {
+    pub(crate) fn resolver(self, db: &impl DefDatabase) -> Resolver {
+        match self {
+            Container::Trait(trait_) => trait_.resolver(db),
+            Container::ImplBlock(impl_block) => impl_block.resolver(db),
+        }
+    }
+}