Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

12 files changed, 8303 insertions, 0 deletions

diff --git a/src/tools/rust-analyzer/crates/hir/Cargo.toml b/src/tools/rust-analyzer/crates/hir/Cargo.toml
new file mode 100644
index 000000000..8e6a2441b
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/Cargo.toml
@@ -0,0 +1,28 @@
+[package]
+name = "hir"
+version = "0.0.0"
+description = "TBD"
+license = "MIT OR Apache-2.0"
+edition = "2021"
+rust-version = "1.57"
+
+[lib]
+doctest = false
+
+[dependencies]
+rustc-hash = "1.1.0"
+either = "1.7.0"
+arrayvec = "0.7.2"
+itertools = "0.10.3"
+smallvec = "1.9.0"
+once_cell = "1.12.0"
+
+stdx = { path = "../stdx", version = "0.0.0" }
+syntax = { path = "../syntax", version = "0.0.0" }
+base-db = { path = "../base-db", version = "0.0.0" }
+profile = { path = "../profile", version = "0.0.0" }
+hir-expand = { path = "../hir-expand", version = "0.0.0" }
+hir-def = { path = "../hir-def", version = "0.0.0" }
+hir-ty = { path = "../hir-ty", version = "0.0.0" }
+tt = { path = "../tt", version = "0.0.0" }
+cfg = { path = "../cfg", version = "0.0.0" }
diff --git a/src/tools/rust-analyzer/crates/hir/src/attrs.rs b/src/tools/rust-analyzer/crates/hir/src/attrs.rs
new file mode 100644
index 000000000..0bd379340
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/attrs.rs
@@ -0,0 +1,177 @@
+//! Attributes & documentation for hir types.
+
+use hir_def::{
+    attr::{AttrsWithOwner, Documentation},
+    item_scope::ItemInNs,
+    path::ModPath,
+    per_ns::PerNs,
+    resolver::HasResolver,
+    AttrDefId, GenericParamId, ModuleDefId,
+};
+use hir_expand::hygiene::Hygiene;
+use hir_ty::db::HirDatabase;
+use syntax::{ast, AstNode};
+
+use crate::{
+    Adt, AssocItem, Const, ConstParam, Enum, Field, Function, GenericParam, Impl, LifetimeParam,
+    Macro, Module, ModuleDef, Static, Struct, Trait, TypeAlias, TypeParam, Union, Variant,
+};
+
+pub trait HasAttrs {
+    fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner;
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation>;
+    fn resolve_doc_path(
+        self,
+        db: &dyn HirDatabase,
+        link: &str,
+        ns: Option<Namespace>,
+    ) -> Option<ModuleDef>;
+}
+
+#[derive(PartialEq, Eq, Hash, Copy, Clone, Debug)]
+pub enum Namespace {
+    Types,
+    Values,
+    Macros,
+}
+
+macro_rules! impl_has_attrs {
+    ($(($def:ident, $def_id:ident),)*) => {$(
+        impl HasAttrs for $def {
+            fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner {
+                let def = AttrDefId::$def_id(self.into());
+                db.attrs(def)
+            }
+            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+                let def = AttrDefId::$def_id(self.into());
+                db.attrs(def).docs()
+            }
+            fn resolve_doc_path(self, db: &dyn HirDatabase, link: &str, ns: Option<Namespace>) -> Option<ModuleDef> {
+                let def = AttrDefId::$def_id(self.into());
+                resolve_doc_path(db, def, link, ns).map(ModuleDef::from)
+            }
+        }
+    )*};
+}
+
+impl_has_attrs![
+    (Field, FieldId),
+    (Variant, EnumVariantId),
+    (Static, StaticId),
+    (Const, ConstId),
+    (Trait, TraitId),
+    (TypeAlias, TypeAliasId),
+    (Macro, MacroId),
+    (Function, FunctionId),
+    (Adt, AdtId),
+    (Module, ModuleId),
+    (GenericParam, GenericParamId),
+    (Impl, ImplId),
+];
+
+macro_rules! impl_has_attrs_enum {
+    ($($variant:ident),* for $enum:ident) => {$(
+        impl HasAttrs for $variant {
+            fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner {
+                $enum::$variant(self).attrs(db)
+            }
+            fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+                $enum::$variant(self).docs(db)
+            }
+            fn resolve_doc_path(self, db: &dyn HirDatabase, link: &str, ns: Option<Namespace>) -> Option<ModuleDef> {
+                $enum::$variant(self).resolve_doc_path(db, link, ns)
+            }
+        }
+    )*};
+}
+
+impl_has_attrs_enum![Struct, Union, Enum for Adt];
+impl_has_attrs_enum![TypeParam, ConstParam, LifetimeParam for GenericParam];
+
+impl HasAttrs for AssocItem {
+    fn attrs(self, db: &dyn HirDatabase) -> AttrsWithOwner {
+        match self {
+            AssocItem::Function(it) => it.attrs(db),
+            AssocItem::Const(it) => it.attrs(db),
+            AssocItem::TypeAlias(it) => it.attrs(db),
+        }
+    }
+
+    fn docs(self, db: &dyn HirDatabase) -> Option<Documentation> {
+        match self {
+            AssocItem::Function(it) => it.docs(db),
+            AssocItem::Const(it) => it.docs(db),
+            AssocItem::TypeAlias(it) => it.docs(db),
+        }
+    }
+
+    fn resolve_doc_path(
+        self,
+        db: &dyn HirDatabase,
+        link: &str,
+        ns: Option<Namespace>,
+    ) -> Option<ModuleDef> {
+        match self {
+            AssocItem::Function(it) => it.resolve_doc_path(db, link, ns),
+            AssocItem::Const(it) => it.resolve_doc_path(db, link, ns),
+            AssocItem::TypeAlias(it) => it.resolve_doc_path(db, link, ns),
+        }
+    }
+}
+
+fn resolve_doc_path(
+    db: &dyn HirDatabase,
+    def: AttrDefId,
+    link: &str,
+    ns: Option<Namespace>,
+) -> Option<ModuleDefId> {
+    let resolver = match def {
+        AttrDefId::ModuleId(it) => it.resolver(db.upcast()),
+        AttrDefId::FieldId(it) => it.parent.resolver(db.upcast()),
+        AttrDefId::AdtId(it) => it.resolver(db.upcast()),
+        AttrDefId::FunctionId(it) => it.resolver(db.upcast()),
+        AttrDefId::EnumVariantId(it) => it.parent.resolver(db.upcast()),
+        AttrDefId::StaticId(it) => it.resolver(db.upcast()),
+        AttrDefId::ConstId(it) => it.resolver(db.upcast()),
+        AttrDefId::TraitId(it) => it.resolver(db.upcast()),
+        AttrDefId::TypeAliasId(it) => it.resolver(db.upcast()),
+        AttrDefId::ImplId(it) => it.resolver(db.upcast()),
+        AttrDefId::ExternBlockId(it) => it.resolver(db.upcast()),
+        AttrDefId::MacroId(it) => it.resolver(db.upcast()),
+        AttrDefId::GenericParamId(it) => match it {
+            GenericParamId::TypeParamId(it) => it.parent(),
+            GenericParamId::ConstParamId(it) => it.parent(),
+            GenericParamId::LifetimeParamId(it) => it.parent,
+        }
+        .resolver(db.upcast()),
+    };
+
+    let modpath = {
+        // FIXME: this is not how we should get a mod path here
+        let ast_path = ast::SourceFile::parse(&format!("type T = {};", link))
+            .syntax_node()
+            .descendants()
+            .find_map(ast::Path::cast)?;
+        if ast_path.to_string() != link {
+            return None;
+        }
+        ModPath::from_src(db.upcast(), ast_path, &Hygiene::new_unhygienic())?
+    };
+
+    let resolved = resolver.resolve_module_path_in_items(db.upcast(), &modpath);
+    let resolved = if resolved == PerNs::none() {
+        resolver.resolve_module_path_in_trait_assoc_items(db.upcast(), &modpath)?
+    } else {
+        resolved
+    };
+    match ns {
+        Some(Namespace::Types) => resolved.take_types(),
+        Some(Namespace::Values) => resolved.take_values(),
+        Some(Namespace::Macros) => resolved.take_macros().map(ModuleDefId::MacroId),
+        None => resolved.iter_items().next().map(|it| match it {
+            ItemInNs::Types(it) => it,
+            ItemInNs::Values(it) => it,
+            ItemInNs::Macros(it) => ModuleDefId::MacroId(it),
+        }),
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/db.rs b/src/tools/rust-analyzer/crates/hir/src/db.rs
new file mode 100644
index 000000000..e25d86784
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/db.rs
@@ -0,0 +1,16 @@
+//! Re-exports various subcrates databases so that the calling code can depend
+//! only on `hir`. This breaks abstraction boundary a bit, it would be cool if
+//! we didn't do that.
+//!
+//! But we need this for at least LRU caching at the query level.
+pub use hir_def::db::*;
+pub use hir_expand::db::{
+    AstDatabase, AstDatabaseStorage, AstIdMapQuery, HygieneFrameQuery, InternMacroCallQuery,
+    MacroArgTextQuery, MacroDefQuery, MacroExpandQuery, ParseMacroExpansionQuery,
+};
+pub use hir_ty::db::*;
+
+#[test]
+fn hir_database_is_object_safe() {
+    fn _assert_object_safe(_: &dyn HirDatabase) {}
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/diagnostics.rs b/src/tools/rust-analyzer/crates/hir/src/diagnostics.rs
new file mode 100644
index 000000000..6c6c11ea4
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/diagnostics.rs
@@ -0,0 +1,170 @@
+//! Re-export diagnostics such that clients of `hir` don't have to depend on
+//! low-level crates.
+//!
+//! This probably isn't the best way to do this -- ideally, diagnistics should
+//! be expressed in terms of hir types themselves.
+use base_db::CrateId;
+use cfg::{CfgExpr, CfgOptions};
+use either::Either;
+use hir_def::path::ModPath;
+use hir_expand::{name::Name, HirFileId, InFile};
+use syntax::{ast, AstPtr, SyntaxNodePtr, TextRange};
+
+use crate::{MacroKind, Type};
+
+macro_rules! diagnostics {
+    ($($diag:ident,)*) => {
+        pub enum AnyDiagnostic {$(
+            $diag(Box<$diag>),
+        )*}
+
+        $(
+            impl From<$diag> for AnyDiagnostic {
+                fn from(d: $diag) -> AnyDiagnostic {
+                    AnyDiagnostic::$diag(Box::new(d))
+                }
+            }
+        )*
+    };
+}
+
+diagnostics![
+    BreakOutsideOfLoop,
+    InactiveCode,
+    IncorrectCase,
+    InvalidDeriveTarget,
+    MacroError,
+    MalformedDerive,
+    MismatchedArgCount,
+    MissingFields,
+    MissingMatchArms,
+    MissingUnsafe,
+    NoSuchField,
+    ReplaceFilterMapNextWithFindMap,
+    TypeMismatch,
+    UnimplementedBuiltinMacro,
+    UnresolvedExternCrate,
+    UnresolvedImport,
+    UnresolvedMacroCall,
+    UnresolvedModule,
+    UnresolvedProcMacro,
+];
+
+#[derive(Debug)]
+pub struct UnresolvedModule {
+    pub decl: InFile<AstPtr<ast::Module>>,
+    pub candidates: Box<[String]>,
+}
+
+#[derive(Debug)]
+pub struct UnresolvedExternCrate {
+    pub decl: InFile<AstPtr<ast::ExternCrate>>,
+}
+
+#[derive(Debug)]
+pub struct UnresolvedImport {
+    pub decl: InFile<AstPtr<ast::UseTree>>,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedMacroCall {
+    pub macro_call: InFile<SyntaxNodePtr>,
+    pub precise_location: Option<TextRange>,
+    pub path: ModPath,
+    pub is_bang: bool,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct InactiveCode {
+    pub node: InFile<SyntaxNodePtr>,
+    pub cfg: CfgExpr,
+    pub opts: CfgOptions,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedProcMacro {
+    pub node: InFile<SyntaxNodePtr>,
+    /// If the diagnostic can be pinpointed more accurately than via `node`, this is the `TextRange`
+    /// to use instead.
+    pub precise_location: Option<TextRange>,
+    pub macro_name: Option<String>,
+    pub kind: MacroKind,
+    /// The crate id of the proc-macro this macro belongs to, or `None` if the proc-macro can't be found.
+    pub krate: CrateId,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct MacroError {
+    pub node: InFile<SyntaxNodePtr>,
+    pub precise_location: Option<TextRange>,
+    pub message: String,
+}
+
+#[derive(Debug)]
+pub struct UnimplementedBuiltinMacro {
+    pub node: InFile<SyntaxNodePtr>,
+}
+
+#[derive(Debug)]
+pub struct InvalidDeriveTarget {
+    pub node: InFile<SyntaxNodePtr>,
+}
+
+#[derive(Debug)]
+pub struct MalformedDerive {
+    pub node: InFile<SyntaxNodePtr>,
+}
+
+#[derive(Debug)]
+pub struct NoSuchField {
+    pub field: InFile<AstPtr<ast::RecordExprField>>,
+}
+
+#[derive(Debug)]
+pub struct BreakOutsideOfLoop {
+    pub expr: InFile<AstPtr<ast::Expr>>,
+}
+
+#[derive(Debug)]
+pub struct MissingUnsafe {
+    pub expr: InFile<AstPtr<ast::Expr>>,
+}
+
+#[derive(Debug)]
+pub struct MissingFields {
+    pub file: HirFileId,
+    pub field_list_parent: Either<AstPtr<ast::RecordExpr>, AstPtr<ast::RecordPat>>,
+    pub field_list_parent_path: Option<AstPtr<ast::Path>>,
+    pub missed_fields: Vec<Name>,
+}
+
+#[derive(Debug)]
+pub struct ReplaceFilterMapNextWithFindMap {
+    pub file: HirFileId,
+    /// This expression is the whole method chain up to and including `.filter_map(..).next()`.
+    pub next_expr: AstPtr<ast::Expr>,
+}
+
+#[derive(Debug)]
+pub struct MismatchedArgCount {
+    pub call_expr: InFile<AstPtr<ast::Expr>>,
+    pub expected: usize,
+    pub found: usize,
+}
+
+#[derive(Debug)]
+pub struct MissingMatchArms {
+    pub file: HirFileId,
+    pub match_expr: AstPtr<ast::Expr>,
+    pub uncovered_patterns: String,
+}
+
+#[derive(Debug)]
+pub struct TypeMismatch {
+    // FIXME: add mismatches in patterns as well
+    pub expr: InFile<AstPtr<ast::Expr>>,
+    pub expected: Type,
+    pub actual: Type,
+}
+
+pub use hir_ty::diagnostics::IncorrectCase;
diff --git a/src/tools/rust-analyzer/crates/hir/src/display.rs b/src/tools/rust-analyzer/crates/hir/src/display.rs
new file mode 100644
index 000000000..0e29c52ad
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/display.rs
@@ -0,0 +1,530 @@
+//! HirDisplay implementations for various hir types.
+use hir_def::{
+    adt::VariantData,
+    generics::{
+        TypeOrConstParamData, TypeParamProvenance, WherePredicate, WherePredicateTypeTarget,
+    },
+    type_ref::{TypeBound, TypeRef},
+    AdtId, GenericDefId,
+};
+use hir_ty::{
+    display::{
+        write_bounds_like_dyn_trait_with_prefix, write_visibility, HirDisplay, HirDisplayError,
+        HirFormatter, SizedByDefault,
+    },
+    Interner, TraitRefExt, WhereClause,
+};
+use syntax::SmolStr;
+
+use crate::{
+    Adt, Const, ConstParam, Enum, Field, Function, GenericParam, HasCrate, HasVisibility,
+    LifetimeParam, Macro, Module, Static, Struct, Trait, TyBuilder, Type, TypeAlias,
+    TypeOrConstParam, TypeParam, Union, Variant,
+};
+
+impl HirDisplay for Function {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        let data = f.db.function_data(self.id);
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        if data.has_default_kw() {
+            f.write_str("default ")?;
+        }
+        if data.has_const_kw() {
+            f.write_str("const ")?;
+        }
+        if data.has_async_kw() {
+            f.write_str("async ")?;
+        }
+        if self.is_unsafe_to_call(f.db) {
+            f.write_str("unsafe ")?;
+        }
+        if let Some(abi) = &data.abi {
+            // FIXME: String escape?
+            write!(f, "extern \"{}\" ", &**abi)?;
+        }
+        write!(f, "fn {}", data.name)?;
+
+        write_generic_params(GenericDefId::FunctionId(self.id), f)?;
+
+        f.write_char('(')?;
+
+        let write_self_param = |ty: &TypeRef, f: &mut HirFormatter<'_>| match ty {
+            TypeRef::Path(p) if p.is_self_type() => f.write_str("self"),
+            TypeRef::Reference(inner, lifetime, mut_) if matches!(&**inner,TypeRef::Path(p) if p.is_self_type()) =>
+            {
+                f.write_char('&')?;
+                if let Some(lifetime) = lifetime {
+                    write!(f, "{} ", lifetime.name)?;
+                }
+                if let hir_def::type_ref::Mutability::Mut = mut_ {
+                    f.write_str("mut ")?;
+                }
+                f.write_str("self")
+            }
+            _ => {
+                f.write_str("self: ")?;
+                ty.hir_fmt(f)
+            }
+        };
+
+        let mut first = true;
+        for (name, type_ref) in &data.params {
+            if !first {
+                f.write_str(", ")?;
+            } else {
+                first = false;
+                if data.has_self_param() {
+                    write_self_param(type_ref, f)?;
+                    continue;
+                }
+            }
+            match name {
+                Some(name) => write!(f, "{}: ", name)?,
+                None => f.write_str("_: ")?,
+            }
+            // FIXME: Use resolved `param.ty` or raw `type_ref`?
+            // The former will ignore lifetime arguments currently.
+            type_ref.hir_fmt(f)?;
+        }
+
+        if data.is_varargs() {
+            f.write_str(", ...")?;
+        }
+
+        f.write_char(')')?;
+
+        // `FunctionData::ret_type` will be `::core::future::Future<Output = ...>` for async fns.
+        // Use ugly pattern match to strip the Future trait.
+        // Better way?
+        let ret_type = if !data.has_async_kw() {
+            &data.ret_type
+        } else {
+            match &*data.ret_type {
+                TypeRef::ImplTrait(bounds) => match bounds[0].as_ref() {
+                    TypeBound::Path(path, _) => {
+                        path.segments().iter().last().unwrap().args_and_bindings.unwrap().bindings
+                            [0]
+                        .type_ref
+                        .as_ref()
+                        .unwrap()
+                    }
+                    _ => panic!("Async fn ret_type should be impl Future"),
+                },
+                _ => panic!("Async fn ret_type should be impl Future"),
+            }
+        };
+
+        match ret_type {
+            TypeRef::Tuple(tup) if tup.is_empty() => {}
+            ty => {
+                f.write_str(" -> ")?;
+                ty.hir_fmt(f)?;
+            }
+        }
+
+        write_where_clause(GenericDefId::FunctionId(self.id), f)?;
+
+        Ok(())
+    }
+}
+
+impl HirDisplay for Adt {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        match self {
+            Adt::Struct(it) => it.hir_fmt(f),
+            Adt::Union(it) => it.hir_fmt(f),
+            Adt::Enum(it) => it.hir_fmt(f),
+        }
+    }
+}
+
+impl HirDisplay for Struct {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        f.write_str("struct ")?;
+        write!(f, "{}", self.name(f.db))?;
+        let def_id = GenericDefId::AdtId(AdtId::StructId(self.id));
+        write_generic_params(def_id, f)?;
+        write_where_clause(def_id, f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Enum {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        f.write_str("enum ")?;
+        write!(f, "{}", self.name(f.db))?;
+        let def_id = GenericDefId::AdtId(AdtId::EnumId(self.id));
+        write_generic_params(def_id, f)?;
+        write_where_clause(def_id, f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Union {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        f.write_str("union ")?;
+        write!(f, "{}", self.name(f.db))?;
+        let def_id = GenericDefId::AdtId(AdtId::UnionId(self.id));
+        write_generic_params(def_id, f)?;
+        write_where_clause(def_id, f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Field {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.parent.module(f.db).id, self.visibility(f.db), f)?;
+        write!(f, "{}: ", self.name(f.db))?;
+        self.ty(f.db).hir_fmt(f)
+    }
+}
+
+impl HirDisplay for Variant {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write!(f, "{}", self.name(f.db))?;
+        let data = self.variant_data(f.db);
+        match &*data {
+            VariantData::Unit => {}
+            VariantData::Tuple(fields) => {
+                f.write_char('(')?;
+                let mut first = true;
+                for (_, field) in fields.iter() {
+                    if first {
+                        first = false;
+                    } else {
+                        f.write_str(", ")?;
+                    }
+                    // Enum variant fields must be pub.
+                    field.type_ref.hir_fmt(f)?;
+                }
+                f.write_char(')')?;
+            }
+            VariantData::Record(fields) => {
+                f.write_str(" {")?;
+                let mut first = true;
+                for (_, field) in fields.iter() {
+                    if first {
+                        first = false;
+                        f.write_char(' ')?;
+                    } else {
+                        f.write_str(", ")?;
+                    }
+                    // Enum variant fields must be pub.
+                    write!(f, "{}: ", field.name)?;
+                    field.type_ref.hir_fmt(f)?;
+                }
+                f.write_str(" }")?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for Type {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        self.ty.hir_fmt(f)
+    }
+}
+
+impl HirDisplay for GenericParam {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        match self {
+            GenericParam::TypeParam(it) => it.hir_fmt(f),
+            GenericParam::ConstParam(it) => it.hir_fmt(f),
+            GenericParam::LifetimeParam(it) => it.hir_fmt(f),
+        }
+    }
+}
+
+impl HirDisplay for TypeOrConstParam {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        match self.split(f.db) {
+            either::Either::Left(x) => x.hir_fmt(f),
+            either::Either::Right(x) => x.hir_fmt(f),
+        }
+    }
+}
+
+impl HirDisplay for TypeParam {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write!(f, "{}", self.name(f.db))?;
+        if f.omit_verbose_types() {
+            return Ok(());
+        }
+
+        let bounds = f.db.generic_predicates_for_param(self.id.parent(), self.id.into(), None);
+        let substs = TyBuilder::placeholder_subst(f.db, self.id.parent());
+        let predicates: Vec<_> =
+            bounds.iter().cloned().map(|b| b.substitute(Interner, &substs)).collect();
+        let krate = self.id.parent().krate(f.db).id;
+        let sized_trait =
+            f.db.lang_item(krate, SmolStr::new_inline("sized"))
+                .and_then(|lang_item| lang_item.as_trait());
+        let has_only_sized_bound = predicates.iter().all(move |pred| match pred.skip_binders() {
+            WhereClause::Implemented(it) => Some(it.hir_trait_id()) == sized_trait,
+            _ => false,
+        });
+        let has_only_not_sized_bound = predicates.is_empty();
+        if !has_only_sized_bound || has_only_not_sized_bound {
+            let default_sized = SizedByDefault::Sized { anchor: krate };
+            write_bounds_like_dyn_trait_with_prefix(":", &predicates, default_sized, f)?;
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for LifetimeParam {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write!(f, "{}", self.name(f.db))
+    }
+}
+
+impl HirDisplay for ConstParam {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write!(f, "const {}: ", self.name(f.db))?;
+        self.ty(f.db).hir_fmt(f)
+    }
+}
+
+fn write_generic_params(
+    def: GenericDefId,
+    f: &mut HirFormatter<'_>,
+) -> Result<(), HirDisplayError> {
+    let params = f.db.generic_params(def);
+    if params.lifetimes.is_empty()
+        && params.type_or_consts.iter().all(|x| x.1.const_param().is_none())
+        && params
+            .type_or_consts
+            .iter()
+            .filter_map(|x| x.1.type_param())
+            .all(|param| !matches!(param.provenance, TypeParamProvenance::TypeParamList))
+    {
+        return Ok(());
+    }
+    f.write_char('<')?;
+
+    let mut first = true;
+    let mut delim = |f: &mut HirFormatter<'_>| {
+        if first {
+            first = false;
+            Ok(())
+        } else {
+            f.write_str(", ")
+        }
+    };
+    for (_, lifetime) in params.lifetimes.iter() {
+        delim(f)?;
+        write!(f, "{}", lifetime.name)?;
+    }
+    for (_, ty) in params.type_or_consts.iter() {
+        if let Some(name) = &ty.name() {
+            match ty {
+                TypeOrConstParamData::TypeParamData(ty) => {
+                    if ty.provenance != TypeParamProvenance::TypeParamList {
+                        continue;
+                    }
+                    delim(f)?;
+                    write!(f, "{}", name)?;
+                    if let Some(default) = &ty.default {
+                        f.write_str(" = ")?;
+                        default.hir_fmt(f)?;
+                    }
+                }
+                TypeOrConstParamData::ConstParamData(c) => {
+                    delim(f)?;
+                    write!(f, "const {}: ", name)?;
+                    c.ty.hir_fmt(f)?;
+                }
+            }
+        }
+    }
+
+    f.write_char('>')?;
+    Ok(())
+}
+
+fn write_where_clause(def: GenericDefId, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+    let params = f.db.generic_params(def);
+
+    // unnamed type targets are displayed inline with the argument itself, e.g. `f: impl Y`.
+    let is_unnamed_type_target = |target: &WherePredicateTypeTarget| match target {
+        WherePredicateTypeTarget::TypeRef(_) => false,
+        WherePredicateTypeTarget::TypeOrConstParam(id) => {
+            params.type_or_consts[*id].name().is_none()
+        }
+    };
+
+    let has_displayable_predicate = params
+        .where_predicates
+        .iter()
+        .any(|pred| {
+            !matches!(pred, WherePredicate::TypeBound { target, .. } if is_unnamed_type_target(target))
+        });
+
+    if !has_displayable_predicate {
+        return Ok(());
+    }
+
+    let write_target = |target: &WherePredicateTypeTarget, f: &mut HirFormatter<'_>| match target {
+        WherePredicateTypeTarget::TypeRef(ty) => ty.hir_fmt(f),
+        WherePredicateTypeTarget::TypeOrConstParam(id) => {
+            match &params.type_or_consts[*id].name() {
+                Some(name) => write!(f, "{}", name),
+                None => f.write_str("{unnamed}"),
+            }
+        }
+    };
+
+    f.write_str("\nwhere")?;
+
+    for (pred_idx, pred) in params.where_predicates.iter().enumerate() {
+        let prev_pred =
+            if pred_idx == 0 { None } else { Some(&params.where_predicates[pred_idx - 1]) };
+
+        let new_predicate = |f: &mut HirFormatter<'_>| {
+            f.write_str(if pred_idx == 0 { "\n    " } else { ",\n    " })
+        };
+
+        match pred {
+            WherePredicate::TypeBound { target, .. } if is_unnamed_type_target(target) => {}
+            WherePredicate::TypeBound { target, bound } => {
+                if matches!(prev_pred, Some(WherePredicate::TypeBound { target: target_, .. }) if target_ == target)
+                {
+                    f.write_str(" + ")?;
+                } else {
+                    new_predicate(f)?;
+                    write_target(target, f)?;
+                    f.write_str(": ")?;
+                }
+                bound.hir_fmt(f)?;
+            }
+            WherePredicate::Lifetime { target, bound } => {
+                if matches!(prev_pred, Some(WherePredicate::Lifetime { target: target_, .. }) if target_ == target)
+                {
+                    write!(f, " + {}", bound.name)?;
+                } else {
+                    new_predicate(f)?;
+                    write!(f, "{}: {}", target.name, bound.name)?;
+                }
+            }
+            WherePredicate::ForLifetime { lifetimes, target, bound } => {
+                if matches!(
+                    prev_pred,
+                    Some(WherePredicate::ForLifetime { lifetimes: lifetimes_, target: target_, .. })
+                    if lifetimes_ == lifetimes && target_ == target,
+                ) {
+                    f.write_str(" + ")?;
+                } else {
+                    new_predicate(f)?;
+                    f.write_str("for<")?;
+                    for (idx, lifetime) in lifetimes.iter().enumerate() {
+                        if idx != 0 {
+                            f.write_str(", ")?;
+                        }
+                        write!(f, "{}", lifetime)?;
+                    }
+                    f.write_str("> ")?;
+                    write_target(target, f)?;
+                    f.write_str(": ")?;
+                }
+                bound.hir_fmt(f)?;
+            }
+        }
+    }
+
+    // End of final predicate. There must be at least one predicate here.
+    f.write_char(',')?;
+
+    Ok(())
+}
+
+impl HirDisplay for Const {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        let data = f.db.const_data(self.id);
+        f.write_str("const ")?;
+        match &data.name {
+            Some(name) => write!(f, "{}: ", name)?,
+            None => f.write_str("_: ")?,
+        }
+        data.type_ref.hir_fmt(f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Static {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        let data = f.db.static_data(self.id);
+        f.write_str("static ")?;
+        if data.mutable {
+            f.write_str("mut ")?;
+        }
+        write!(f, "{}: ", &data.name)?;
+        data.type_ref.hir_fmt(f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Trait {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        let data = f.db.trait_data(self.id);
+        if data.is_unsafe {
+            f.write_str("unsafe ")?;
+        }
+        if data.is_auto {
+            f.write_str("auto ")?;
+        }
+        write!(f, "trait {}", data.name)?;
+        let def_id = GenericDefId::TraitId(self.id);
+        write_generic_params(def_id, f)?;
+        write_where_clause(def_id, f)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for TypeAlias {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
+        let data = f.db.type_alias_data(self.id);
+        write!(f, "type {}", data.name)?;
+        if !data.bounds.is_empty() {
+            f.write_str(": ")?;
+            f.write_joined(&data.bounds, " + ")?;
+        }
+        if let Some(ty) = &data.type_ref {
+            f.write_str(" = ")?;
+            ty.hir_fmt(f)?;
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for Module {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        // FIXME: Module doesn't have visibility saved in data.
+        match self.name(f.db) {
+            Some(name) => write!(f, "mod {}", name),
+            None if self.is_crate_root(f.db) => match self.krate(f.db).display_name(f.db) {
+                Some(name) => write!(f, "extern crate {}", name),
+                None => f.write_str("extern crate {unknown}"),
+            },
+            None => f.write_str("mod {unnamed}"),
+        }
+    }
+}
+
+impl HirDisplay for Macro {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        match self.id {
+            hir_def::MacroId::Macro2Id(_) => f.write_str("macro"),
+            hir_def::MacroId::MacroRulesId(_) => f.write_str("macro_rules!"),
+            hir_def::MacroId::ProcMacroId(_) => f.write_str("proc_macro"),
+        }?;
+        write!(f, " {}", self.name(f.db))
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/from_id.rs b/src/tools/rust-analyzer/crates/hir/src/from_id.rs
new file mode 100644
index 000000000..9c7558d19
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/from_id.rs
@@ -0,0 +1,293 @@
+//! Utility module for converting between hir_def ids and code_model wrappers.
+//!
+//! It's unclear if we need this long-term, but it's definitely useful while we
+//! are splitting the hir.
+
+use hir_def::{
+    expr::{LabelId, PatId},
+    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, GenericDefId, GenericParamId,
+    ModuleDefId, VariantId,
+};
+
+use crate::{
+    Adt, AssocItem, BuiltinType, DefWithBody, Field, GenericDef, GenericParam, ItemInNs, Label,
+    Local, ModuleDef, Variant, VariantDef,
+};
+
+macro_rules! from_id {
+    ($(($id:path, $ty:path)),*) => {$(
+        impl From<$id> for $ty {
+            fn from(id: $id) -> $ty {
+                $ty { id }
+            }
+        }
+        impl From<$ty> for $id {
+            fn from(ty: $ty) -> $id {
+                ty.id
+            }
+        }
+    )*}
+}
+
+from_id![
+    (base_db::CrateId, crate::Crate),
+    (hir_def::ModuleId, crate::Module),
+    (hir_def::StructId, crate::Struct),
+    (hir_def::UnionId, crate::Union),
+    (hir_def::EnumId, crate::Enum),
+    (hir_def::TypeAliasId, crate::TypeAlias),
+    (hir_def::TraitId, crate::Trait),
+    (hir_def::StaticId, crate::Static),
+    (hir_def::ConstId, crate::Const),
+    (hir_def::FunctionId, crate::Function),
+    (hir_def::ImplId, crate::Impl),
+    (hir_def::TypeOrConstParamId, crate::TypeOrConstParam),
+    (hir_def::TypeParamId, crate::TypeParam),
+    (hir_def::ConstParamId, crate::ConstParam),
+    (hir_def::LifetimeParamId, crate::LifetimeParam),
+    (hir_def::MacroId, crate::Macro)
+];
+
+impl From<AdtId> for Adt {
+    fn from(id: AdtId) -> Self {
+        match id {
+            AdtId::StructId(it) => Adt::Struct(it.into()),
+            AdtId::UnionId(it) => Adt::Union(it.into()),
+            AdtId::EnumId(it) => Adt::Enum(it.into()),
+        }
+    }
+}
+
+impl From<Adt> for AdtId {
+    fn from(id: Adt) -> Self {
+        match id {
+            Adt::Struct(it) => AdtId::StructId(it.id),
+            Adt::Union(it) => AdtId::UnionId(it.id),
+            Adt::Enum(it) => AdtId::EnumId(it.id),
+        }
+    }
+}
+
+impl From<GenericParamId> for GenericParam {
+    fn from(id: GenericParamId) -> Self {
+        match id {
+            GenericParamId::TypeParamId(it) => GenericParam::TypeParam(it.into()),
+            GenericParamId::ConstParamId(it) => GenericParam::ConstParam(it.into()),
+            GenericParamId::LifetimeParamId(it) => GenericParam::LifetimeParam(it.into()),
+        }
+    }
+}
+
+impl From<GenericParam> for GenericParamId {
+    fn from(id: GenericParam) -> Self {
+        match id {
+            GenericParam::LifetimeParam(it) => GenericParamId::LifetimeParamId(it.id),
+            GenericParam::ConstParam(it) => GenericParamId::ConstParamId(it.id),
+            GenericParam::TypeParam(it) => GenericParamId::TypeParamId(it.id),
+        }
+    }
+}
+
+impl From<EnumVariantId> for Variant {
+    fn from(id: EnumVariantId) -> Self {
+        Variant { parent: id.parent.into(), id: id.local_id }
+    }
+}
+
+impl From<Variant> for EnumVariantId {
+    fn from(def: Variant) -> Self {
+        EnumVariantId { parent: def.parent.id, local_id: def.id }
+    }
+}
+
+impl From<ModuleDefId> for ModuleDef {
+    fn from(id: ModuleDefId) -> Self {
+        match id {
+            ModuleDefId::ModuleId(it) => ModuleDef::Module(it.into()),
+            ModuleDefId::FunctionId(it) => ModuleDef::Function(it.into()),
+            ModuleDefId::AdtId(it) => ModuleDef::Adt(it.into()),
+            ModuleDefId::EnumVariantId(it) => ModuleDef::Variant(it.into()),
+            ModuleDefId::ConstId(it) => ModuleDef::Const(it.into()),
+            ModuleDefId::StaticId(it) => ModuleDef::Static(it.into()),
+            ModuleDefId::TraitId(it) => ModuleDef::Trait(it.into()),
+            ModuleDefId::TypeAliasId(it) => ModuleDef::TypeAlias(it.into()),
+            ModuleDefId::BuiltinType(it) => ModuleDef::BuiltinType(it.into()),
+            ModuleDefId::MacroId(it) => ModuleDef::Macro(it.into()),
+        }
+    }
+}
+
+impl From<ModuleDef> for ModuleDefId {
+    fn from(id: ModuleDef) -> Self {
+        match id {
+            ModuleDef::Module(it) => ModuleDefId::ModuleId(it.into()),
+            ModuleDef::Function(it) => ModuleDefId::FunctionId(it.into()),
+            ModuleDef::Adt(it) => ModuleDefId::AdtId(it.into()),
+            ModuleDef::Variant(it) => ModuleDefId::EnumVariantId(it.into()),
+            ModuleDef::Const(it) => ModuleDefId::ConstId(it.into()),
+            ModuleDef::Static(it) => ModuleDefId::StaticId(it.into()),
+            ModuleDef::Trait(it) => ModuleDefId::TraitId(it.into()),
+            ModuleDef::TypeAlias(it) => ModuleDefId::TypeAliasId(it.into()),
+            ModuleDef::BuiltinType(it) => ModuleDefId::BuiltinType(it.into()),
+            ModuleDef::Macro(it) => ModuleDefId::MacroId(it.into()),
+        }
+    }
+}
+
+impl From<DefWithBody> for DefWithBodyId {
+    fn from(def: DefWithBody) -> Self {
+        match def {
+            DefWithBody::Function(it) => DefWithBodyId::FunctionId(it.id),
+            DefWithBody::Static(it) => DefWithBodyId::StaticId(it.id),
+            DefWithBody::Const(it) => DefWithBodyId::ConstId(it.id),
+        }
+    }
+}
+
+impl From<DefWithBodyId> for DefWithBody {
+    fn from(def: DefWithBodyId) -> Self {
+        match def {
+            DefWithBodyId::FunctionId(it) => DefWithBody::Function(it.into()),
+            DefWithBodyId::StaticId(it) => DefWithBody::Static(it.into()),
+            DefWithBodyId::ConstId(it) => DefWithBody::Const(it.into()),
+        }
+    }
+}
+
+impl From<AssocItemId> for AssocItem {
+    fn from(def: AssocItemId) -> Self {
+        match def {
+            AssocItemId::FunctionId(it) => AssocItem::Function(it.into()),
+            AssocItemId::TypeAliasId(it) => AssocItem::TypeAlias(it.into()),
+            AssocItemId::ConstId(it) => AssocItem::Const(it.into()),
+        }
+    }
+}
+
+impl From<GenericDef> for GenericDefId {
+    fn from(def: GenericDef) -> Self {
+        match def {
+            GenericDef::Function(it) => GenericDefId::FunctionId(it.id),
+            GenericDef::Adt(it) => GenericDefId::AdtId(it.into()),
+            GenericDef::Trait(it) => GenericDefId::TraitId(it.id),
+            GenericDef::TypeAlias(it) => GenericDefId::TypeAliasId(it.id),
+            GenericDef::Impl(it) => GenericDefId::ImplId(it.id),
+            GenericDef::Variant(it) => {
+                GenericDefId::EnumVariantId(EnumVariantId { parent: it.parent.id, local_id: it.id })
+            }
+            GenericDef::Const(it) => GenericDefId::ConstId(it.id),
+        }
+    }
+}
+
+impl From<GenericDefId> for GenericDef {
+    fn from(def: GenericDefId) -> Self {
+        match def {
+            GenericDefId::FunctionId(it) => GenericDef::Function(it.into()),
+            GenericDefId::AdtId(it) => GenericDef::Adt(it.into()),
+            GenericDefId::TraitId(it) => GenericDef::Trait(it.into()),
+            GenericDefId::TypeAliasId(it) => GenericDef::TypeAlias(it.into()),
+            GenericDefId::ImplId(it) => GenericDef::Impl(it.into()),
+            GenericDefId::EnumVariantId(it) => {
+                GenericDef::Variant(Variant { parent: it.parent.into(), id: it.local_id })
+            }
+            GenericDefId::ConstId(it) => GenericDef::Const(it.into()),
+        }
+    }
+}
+
+impl From<Adt> for GenericDefId {
+    fn from(id: Adt) -> Self {
+        match id {
+            Adt::Struct(it) => it.id.into(),
+            Adt::Union(it) => it.id.into(),
+            Adt::Enum(it) => it.id.into(),
+        }
+    }
+}
+
+impl From<VariantId> for VariantDef {
+    fn from(def: VariantId) -> Self {
+        match def {
+            VariantId::StructId(it) => VariantDef::Struct(it.into()),
+            VariantId::EnumVariantId(it) => VariantDef::Variant(it.into()),
+            VariantId::UnionId(it) => VariantDef::Union(it.into()),
+        }
+    }
+}
+
+impl From<VariantDef> for VariantId {
+    fn from(def: VariantDef) -> Self {
+        match def {
+            VariantDef::Struct(it) => VariantId::StructId(it.id),
+            VariantDef::Variant(it) => VariantId::EnumVariantId(it.into()),
+            VariantDef::Union(it) => VariantId::UnionId(it.id),
+        }
+    }
+}
+
+impl From<Field> for FieldId {
+    fn from(def: Field) -> Self {
+        FieldId { parent: def.parent.into(), local_id: def.id }
+    }
+}
+
+impl From<FieldId> for Field {
+    fn from(def: FieldId) -> Self {
+        Field { parent: def.parent.into(), id: def.local_id }
+    }
+}
+
+impl From<AssocItem> for GenericDefId {
+    fn from(item: AssocItem) -> Self {
+        match item {
+            AssocItem::Function(f) => f.id.into(),
+            AssocItem::Const(c) => c.id.into(),
+            AssocItem::TypeAlias(t) => t.id.into(),
+        }
+    }
+}
+
+impl From<(DefWithBodyId, PatId)> for Local {
+    fn from((parent, pat_id): (DefWithBodyId, PatId)) -> Self {
+        Local { parent, pat_id }
+    }
+}
+
+impl From<(DefWithBodyId, LabelId)> for Label {
+    fn from((parent, label_id): (DefWithBodyId, LabelId)) -> Self {
+        Label { parent, label_id }
+    }
+}
+
+impl From<hir_def::item_scope::ItemInNs> for ItemInNs {
+    fn from(it: hir_def::item_scope::ItemInNs) -> Self {
+        match it {
+            hir_def::item_scope::ItemInNs::Types(it) => ItemInNs::Types(it.into()),
+            hir_def::item_scope::ItemInNs::Values(it) => ItemInNs::Values(it.into()),
+            hir_def::item_scope::ItemInNs::Macros(it) => ItemInNs::Macros(it.into()),
+        }
+    }
+}
+
+impl From<ItemInNs> for hir_def::item_scope::ItemInNs {
+    fn from(it: ItemInNs) -> Self {
+        match it {
+            ItemInNs::Types(it) => Self::Types(it.into()),
+            ItemInNs::Values(it) => Self::Values(it.into()),
+            ItemInNs::Macros(it) => Self::Macros(it.into()),
+        }
+    }
+}
+
+impl From<hir_def::builtin_type::BuiltinType> for BuiltinType {
+    fn from(inner: hir_def::builtin_type::BuiltinType) -> Self {
+        Self { inner }
+    }
+}
+
+impl From<BuiltinType> for hir_def::builtin_type::BuiltinType {
+    fn from(it: BuiltinType) -> Self {
+        it.inner
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/has_source.rs b/src/tools/rust-analyzer/crates/hir/src/has_source.rs
new file mode 100644
index 000000000..f8b01db3e
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/has_source.rs
@@ -0,0 +1,174 @@
+//! Provides set of implementation for hir's objects that allows get back location in file.
+
+use either::Either;
+use hir_def::{
+    nameres::{ModuleOrigin, ModuleSource},
+    src::{HasChildSource, HasSource as _},
+    Lookup, MacroId, VariantId,
+};
+use hir_expand::InFile;
+use syntax::ast;
+
+use crate::{
+    db::HirDatabase, Adt, Const, Enum, Field, FieldSource, Function, Impl, LifetimeParam, Macro,
+    Module, Static, Struct, Trait, TypeAlias, TypeOrConstParam, Union, Variant,
+};
+
+pub trait HasSource {
+    type Ast;
+    /// Fetches the definition's source node.
+    /// Using [`crate::Semantics::source`] is preferred when working with [`crate::Semantics`],
+    /// as that caches the parsed file in the semantics' cache.
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>>;
+}
+
+/// NB: Module is !HasSource, because it has two source nodes at the same time:
+/// definition and declaration.
+impl Module {
+    /// Returns a node which defines this module. That is, a file or a `mod foo {}` with items.
+    pub fn definition_source(self, db: &dyn HirDatabase) -> InFile<ModuleSource> {
+        let def_map = self.id.def_map(db.upcast());
+        def_map[self.id.local_id].definition_source(db.upcast())
+    }
+
+    pub fn is_mod_rs(self, db: &dyn HirDatabase) -> bool {
+        let def_map = self.id.def_map(db.upcast());
+        match def_map[self.id.local_id].origin {
+            ModuleOrigin::File { is_mod_rs, .. } => is_mod_rs,
+            _ => false,
+        }
+    }
+
+    pub fn is_inline(self, db: &dyn HirDatabase) -> bool {
+        let def_map = self.id.def_map(db.upcast());
+        def_map[self.id.local_id].origin.is_inline()
+    }
+
+    /// 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: &dyn HirDatabase) -> Option<InFile<ast::Module>> {
+        let def_map = self.id.def_map(db.upcast());
+        def_map[self.id.local_id].declaration_source(db.upcast())
+    }
+}
+
+impl HasSource for Field {
+    type Ast = FieldSource;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        let var = VariantId::from(self.parent);
+        let src = var.child_source(db.upcast());
+        let field_source = src.map(|it| match it[self.id].clone() {
+            Either::Left(it) => FieldSource::Pos(it),
+            Either::Right(it) => FieldSource::Named(it),
+        });
+        Some(field_source)
+    }
+}
+impl HasSource for Adt {
+    type Ast = ast::Adt;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        match self {
+            Adt::Struct(s) => Some(s.source(db)?.map(ast::Adt::Struct)),
+            Adt::Union(u) => Some(u.source(db)?.map(ast::Adt::Union)),
+            Adt::Enum(e) => Some(e.source(db)?.map(ast::Adt::Enum)),
+        }
+    }
+}
+impl HasSource for Struct {
+    type Ast = ast::Struct;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Union {
+    type Ast = ast::Union;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Enum {
+    type Ast = ast::Enum;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Variant {
+    type Ast = ast::Variant;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<ast::Variant>> {
+        Some(self.parent.id.child_source(db.upcast()).map(|map| map[self.id].clone()))
+    }
+}
+impl HasSource for Function {
+    type Ast = ast::Fn;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Const {
+    type Ast = ast::Const;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Static {
+    type Ast = ast::Static;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Trait {
+    type Ast = ast::Trait;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for TypeAlias {
+    type Ast = ast::TypeAlias;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+impl HasSource for Macro {
+    type Ast = Either<ast::Macro, ast::Fn>;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        match self.id {
+            MacroId::Macro2Id(it) => Some(
+                it.lookup(db.upcast())
+                    .source(db.upcast())
+                    .map(ast::Macro::MacroDef)
+                    .map(Either::Left),
+            ),
+            MacroId::MacroRulesId(it) => Some(
+                it.lookup(db.upcast())
+                    .source(db.upcast())
+                    .map(ast::Macro::MacroRules)
+                    .map(Either::Left),
+            ),
+            MacroId::ProcMacroId(it) => {
+                Some(it.lookup(db.upcast()).source(db.upcast()).map(Either::Right))
+            }
+        }
+    }
+}
+impl HasSource for Impl {
+    type Ast = ast::Impl;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        Some(self.id.lookup(db.upcast()).source(db.upcast()))
+    }
+}
+
+impl HasSource for TypeOrConstParam {
+    type Ast = Either<ast::TypeOrConstParam, ast::Trait>;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        let child_source = self.id.parent.child_source(db.upcast());
+        Some(child_source.map(|it| it[self.id.local_id].clone()))
+    }
+}
+
+impl HasSource for LifetimeParam {
+    type Ast = ast::LifetimeParam;
+    fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
+        let child_source = self.id.parent.child_source(db.upcast());
+        Some(child_source.map(|it| it[self.id.local_id].clone()))
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/lib.rs b/src/tools/rust-analyzer/crates/hir/src/lib.rs
new file mode 100644
index 000000000..8f984210e
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/lib.rs
@@ -0,0 +1,3639 @@
+//! HIR (previously known as descriptors) provides a high-level object oriented
+//! access to Rust code.
+//!
+//! The principal difference between HIR and syntax trees is that HIR is bound
+//! to a particular crate instance. That is, it has cfg flags and features
+//! applied. So, the relation between syntax and HIR is many-to-one.
+//!
+//! HIR is the public API of the all of the compiler logic above syntax trees.
+//! It is written in "OO" style. Each type is self contained (as in, it knows it's
+//! parents and full context). It should be "clean code".
+//!
+//! `hir_*` crates are the implementation of the compiler logic.
+//! They are written in "ECS" style, with relatively little abstractions.
+//! Many types are not self-contained, and explicitly use local indexes, arenas, etc.
+//!
+//! `hir` is what insulates the "we don't know how to actually write an incremental compiler"
+//! from the ide with completions, hovers, etc. It is a (soft, internal) boundary:
+//! <https://www.tedinski.com/2018/02/06/system-boundaries.html>.
+
+#![warn(rust_2018_idioms, unused_lifetimes, semicolon_in_expressions_from_macros)]
+#![recursion_limit = "512"]
+
+mod semantics;
+mod source_analyzer;
+
+mod from_id;
+mod attrs;
+mod has_source;
+
+pub mod diagnostics;
+pub mod db;
+pub mod symbols;
+
+mod display;
+
+use std::{iter, ops::ControlFlow, sync::Arc};
+
+use arrayvec::ArrayVec;
+use base_db::{CrateDisplayName, CrateId, CrateOrigin, Edition, FileId, ProcMacroKind};
+use either::Either;
+use hir_def::{
+    adt::{ReprKind, VariantData},
+    body::{BodyDiagnostic, SyntheticSyntax},
+    expr::{BindingAnnotation, LabelId, Pat, PatId},
+    generics::{TypeOrConstParamData, TypeParamProvenance},
+    item_tree::ItemTreeNode,
+    lang_item::LangItemTarget,
+    nameres::{self, diagnostics::DefDiagnostic},
+    per_ns::PerNs,
+    resolver::{HasResolver, Resolver},
+    src::HasSource as _,
+    AdtId, AssocItemId, AssocItemLoc, AttrDefId, ConstId, ConstParamId, DefWithBodyId, EnumId,
+    FunctionId, GenericDefId, HasModule, ImplId, ItemContainerId, LifetimeParamId,
+    LocalEnumVariantId, LocalFieldId, Lookup, MacroExpander, MacroId, ModuleId, StaticId, StructId,
+    TraitId, TypeAliasId, TypeOrConstParamId, TypeParamId, UnionId,
+};
+use hir_expand::{name::name, MacroCallKind};
+use hir_ty::{
+    all_super_traits, autoderef,
+    consteval::{unknown_const_as_generic, ComputedExpr, ConstEvalError, ConstExt},
+    diagnostics::BodyValidationDiagnostic,
+    method_resolution::{self, TyFingerprint},
+    primitive::UintTy,
+    subst_prefix,
+    traits::FnTrait,
+    AliasEq, AliasTy, BoundVar, CallableDefId, CallableSig, Canonical, CanonicalVarKinds, Cast,
+    ClosureId, DebruijnIndex, GenericArgData, InEnvironment, Interner, ParamKind,
+    QuantifiedWhereClause, Scalar, Solution, Substitution, TraitEnvironment, TraitRefExt, Ty,
+    TyBuilder, TyDefId, TyExt, TyKind, TyVariableKind, WhereClause,
+};
+use itertools::Itertools;
+use nameres::diagnostics::DefDiagnosticKind;
+use once_cell::unsync::Lazy;
+use rustc_hash::FxHashSet;
+use stdx::{format_to, impl_from, never};
+use syntax::{
+    ast::{self, HasAttrs as _, HasDocComments, HasName},
+    AstNode, AstPtr, SmolStr, SyntaxNodePtr, TextRange, T,
+};
+
+use crate::db::{DefDatabase, HirDatabase};
+
+pub use crate::{
+    attrs::{HasAttrs, Namespace},
+    diagnostics::{
+        AnyDiagnostic, BreakOutsideOfLoop, InactiveCode, IncorrectCase, InvalidDeriveTarget,
+        MacroError, MalformedDerive, MismatchedArgCount, MissingFields, MissingMatchArms,
+        MissingUnsafe, NoSuchField, ReplaceFilterMapNextWithFindMap, TypeMismatch,
+        UnimplementedBuiltinMacro, UnresolvedExternCrate, UnresolvedImport, UnresolvedMacroCall,
+        UnresolvedModule, UnresolvedProcMacro,
+    },
+    has_source::HasSource,
+    semantics::{PathResolution, Semantics, SemanticsScope, TypeInfo, VisibleTraits},
+};
+
+// Be careful with these re-exports.
+//
+// `hir` is the boundary between the compiler and the IDE. It should try hard to
+// isolate the compiler from the ide, to allow the two to be refactored
+// independently. Re-exporting something from the compiler is the sure way to
+// breach the boundary.
+//
+// Generally, a refactoring which *removes* a name from this list is a good
+// idea!
+pub use {
+    cfg::{CfgAtom, CfgExpr, CfgOptions},
+    hir_def::{
+        adt::StructKind,
+        attr::{Attr, Attrs, AttrsWithOwner, Documentation},
+        builtin_attr::AttributeTemplate,
+        find_path::PrefixKind,
+        import_map,
+        nameres::ModuleSource,
+        path::{ModPath, PathKind},
+        type_ref::{Mutability, TypeRef},
+        visibility::Visibility,
+    },
+    hir_expand::{
+        name::{known, Name},
+        ExpandResult, HirFileId, InFile, MacroFile, Origin,
+    },
+    hir_ty::display::HirDisplay,
+};
+
+// These are negative re-exports: pub using these names is forbidden, they
+// should remain private to hir internals.
+#[allow(unused)]
+use {
+    hir_def::path::Path,
+    hir_expand::{hygiene::Hygiene, name::AsName},
+};
+
+/// 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) id: CrateId,
+}
+
+#[derive(Debug)]
+pub struct CrateDependency {
+    pub krate: Crate,
+    pub name: Name,
+}
+
+impl Crate {
+    pub fn origin(self, db: &dyn HirDatabase) -> CrateOrigin {
+        db.crate_graph()[self.id].origin.clone()
+    }
+
+    pub fn is_builtin(self, db: &dyn HirDatabase) -> bool {
+        matches!(self.origin(db), CrateOrigin::Lang(_))
+    }
+
+    pub fn dependencies(self, db: &dyn HirDatabase) -> Vec<CrateDependency> {
+        db.crate_graph()[self.id]
+            .dependencies
+            .iter()
+            .map(|dep| {
+                let krate = Crate { id: dep.crate_id };
+                let name = dep.as_name();
+                CrateDependency { krate, name }
+            })
+            .collect()
+    }
+
+    pub fn reverse_dependencies(self, db: &dyn HirDatabase) -> Vec<Crate> {
+        let crate_graph = db.crate_graph();
+        crate_graph
+            .iter()
+            .filter(|&krate| {
+                crate_graph[krate].dependencies.iter().any(|it| it.crate_id == self.id)
+            })
+            .map(|id| Crate { id })
+            .collect()
+    }
+
+    pub fn transitive_reverse_dependencies(
+        self,
+        db: &dyn HirDatabase,
+    ) -> impl Iterator<Item = Crate> {
+        db.crate_graph().transitive_rev_deps(self.id).map(|id| Crate { id })
+    }
+
+    pub fn root_module(self, db: &dyn HirDatabase) -> Module {
+        let def_map = db.crate_def_map(self.id);
+        Module { id: def_map.module_id(def_map.root()) }
+    }
+
+    pub fn modules(self, db: &dyn HirDatabase) -> Vec<Module> {
+        let def_map = db.crate_def_map(self.id);
+        def_map.modules().map(|(id, _)| def_map.module_id(id).into()).collect()
+    }
+
+    pub fn root_file(self, db: &dyn HirDatabase) -> FileId {
+        db.crate_graph()[self.id].root_file_id
+    }
+
+    pub fn edition(self, db: &dyn HirDatabase) -> Edition {
+        db.crate_graph()[self.id].edition
+    }
+
+    pub fn version(self, db: &dyn HirDatabase) -> Option<String> {
+        db.crate_graph()[self.id].version.clone()
+    }
+
+    pub fn display_name(self, db: &dyn HirDatabase) -> Option<CrateDisplayName> {
+        db.crate_graph()[self.id].display_name.clone()
+    }
+
+    pub fn query_external_importables(
+        self,
+        db: &dyn DefDatabase,
+        query: import_map::Query,
+    ) -> impl Iterator<Item = Either<ModuleDef, Macro>> {
+        let _p = profile::span("query_external_importables");
+        import_map::search_dependencies(db, self.into(), query).into_iter().map(|item| {
+            match ItemInNs::from(item) {
+                ItemInNs::Types(mod_id) | ItemInNs::Values(mod_id) => Either::Left(mod_id),
+                ItemInNs::Macros(mac_id) => Either::Right(mac_id),
+            }
+        })
+    }
+
+    pub fn all(db: &dyn HirDatabase) -> Vec<Crate> {
+        db.crate_graph().iter().map(|id| Crate { id }).collect()
+    }
+
+    /// Try to get the root URL of the documentation of a crate.
+    pub fn get_html_root_url(self: &Crate, db: &dyn HirDatabase) -> Option<String> {
+        // Look for #![doc(html_root_url = "...")]
+        let attrs = db.attrs(AttrDefId::ModuleId(self.root_module(db).into()));
+        let doc_url = attrs.by_key("doc").find_string_value_in_tt("html_root_url");
+        doc_url.map(|s| s.trim_matches('"').trim_end_matches('/').to_owned() + "/")
+    }
+
+    pub fn cfg(&self, db: &dyn HirDatabase) -> CfgOptions {
+        db.crate_graph()[self.id].cfg_options.clone()
+    }
+
+    pub fn potential_cfg(&self, db: &dyn HirDatabase) -> CfgOptions {
+        db.crate_graph()[self.id].potential_cfg_options.clone()
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Module {
+    pub(crate) id: ModuleId,
+}
+
+/// The defs which can be visible in the module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ModuleDef {
+    Module(Module),
+    Function(Function),
+    Adt(Adt),
+    // Can't be directly declared, but can be imported.
+    Variant(Variant),
+    Const(Const),
+    Static(Static),
+    Trait(Trait),
+    TypeAlias(TypeAlias),
+    BuiltinType(BuiltinType),
+    Macro(Macro),
+}
+impl_from!(
+    Module,
+    Function,
+    Adt(Struct, Enum, Union),
+    Variant,
+    Const,
+    Static,
+    Trait,
+    TypeAlias,
+    BuiltinType,
+    Macro
+    for ModuleDef
+);
+
+impl From<VariantDef> for ModuleDef {
+    fn from(var: VariantDef) -> Self {
+        match var {
+            VariantDef::Struct(t) => Adt::from(t).into(),
+            VariantDef::Union(t) => Adt::from(t).into(),
+            VariantDef::Variant(t) => t.into(),
+        }
+    }
+}
+
+impl ModuleDef {
+    pub fn module(self, db: &dyn HirDatabase) -> Option<Module> {
+        match self {
+            ModuleDef::Module(it) => it.parent(db),
+            ModuleDef::Function(it) => Some(it.module(db)),
+            ModuleDef::Adt(it) => Some(it.module(db)),
+            ModuleDef::Variant(it) => Some(it.module(db)),
+            ModuleDef::Const(it) => Some(it.module(db)),
+            ModuleDef::Static(it) => Some(it.module(db)),
+            ModuleDef::Trait(it) => Some(it.module(db)),
+            ModuleDef::TypeAlias(it) => Some(it.module(db)),
+            ModuleDef::Macro(it) => Some(it.module(db)),
+            ModuleDef::BuiltinType(_) => None,
+        }
+    }
+
+    pub fn canonical_path(&self, db: &dyn HirDatabase) -> Option<String> {
+        let mut segments = vec![self.name(db)?];
+        for m in self.module(db)?.path_to_root(db) {
+            segments.extend(m.name(db))
+        }
+        segments.reverse();
+        Some(segments.into_iter().join("::"))
+    }
+
+    pub fn canonical_module_path(
+        &self,
+        db: &dyn HirDatabase,
+    ) -> Option<impl Iterator<Item = Module>> {
+        self.module(db).map(|it| it.path_to_root(db).into_iter().rev())
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
+        let name = match self {
+            ModuleDef::Module(it) => it.name(db)?,
+            ModuleDef::Const(it) => it.name(db)?,
+            ModuleDef::Adt(it) => it.name(db),
+            ModuleDef::Trait(it) => it.name(db),
+            ModuleDef::Function(it) => it.name(db),
+            ModuleDef::Variant(it) => it.name(db),
+            ModuleDef::TypeAlias(it) => it.name(db),
+            ModuleDef::Static(it) => it.name(db),
+            ModuleDef::Macro(it) => it.name(db),
+            ModuleDef::BuiltinType(it) => it.name(),
+        };
+        Some(name)
+    }
+
+    pub fn diagnostics(self, db: &dyn HirDatabase) -> Vec<AnyDiagnostic> {
+        let id = match self {
+            ModuleDef::Adt(it) => match it {
+                Adt::Struct(it) => it.id.into(),
+                Adt::Enum(it) => it.id.into(),
+                Adt::Union(it) => it.id.into(),
+            },
+            ModuleDef::Trait(it) => it.id.into(),
+            ModuleDef::Function(it) => it.id.into(),
+            ModuleDef::TypeAlias(it) => it.id.into(),
+            ModuleDef::Module(it) => it.id.into(),
+            ModuleDef::Const(it) => it.id.into(),
+            ModuleDef::Static(it) => it.id.into(),
+            _ => return Vec::new(),
+        };
+
+        let module = match self.module(db) {
+            Some(it) => it,
+            None => return Vec::new(),
+        };
+
+        let mut acc = Vec::new();
+
+        match self.as_def_with_body() {
+            Some(def) => {
+                def.diagnostics(db, &mut acc);
+            }
+            None => {
+                for diag in hir_ty::diagnostics::incorrect_case(db, module.id.krate(), id) {
+                    acc.push(diag.into())
+                }
+            }
+        }
+
+        acc
+    }
+
+    pub fn as_def_with_body(self) -> Option<DefWithBody> {
+        match self {
+            ModuleDef::Function(it) => Some(it.into()),
+            ModuleDef::Const(it) => Some(it.into()),
+            ModuleDef::Static(it) => Some(it.into()),
+
+            ModuleDef::Module(_)
+            | ModuleDef::Adt(_)
+            | ModuleDef::Variant(_)
+            | ModuleDef::Trait(_)
+            | ModuleDef::TypeAlias(_)
+            | ModuleDef::Macro(_)
+            | ModuleDef::BuiltinType(_) => None,
+        }
+    }
+
+    pub fn attrs(&self, db: &dyn HirDatabase) -> Option<AttrsWithOwner> {
+        Some(match self {
+            ModuleDef::Module(it) => it.attrs(db),
+            ModuleDef::Function(it) => it.attrs(db),
+            ModuleDef::Adt(it) => it.attrs(db),
+            ModuleDef::Variant(it) => it.attrs(db),
+            ModuleDef::Const(it) => it.attrs(db),
+            ModuleDef::Static(it) => it.attrs(db),
+            ModuleDef::Trait(it) => it.attrs(db),
+            ModuleDef::TypeAlias(it) => it.attrs(db),
+            ModuleDef::Macro(it) => it.attrs(db),
+            ModuleDef::BuiltinType(_) => return None,
+        })
+    }
+}
+
+impl HasVisibility for ModuleDef {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        match *self {
+            ModuleDef::Module(it) => it.visibility(db),
+            ModuleDef::Function(it) => it.visibility(db),
+            ModuleDef::Adt(it) => it.visibility(db),
+            ModuleDef::Const(it) => it.visibility(db),
+            ModuleDef::Static(it) => it.visibility(db),
+            ModuleDef::Trait(it) => it.visibility(db),
+            ModuleDef::TypeAlias(it) => it.visibility(db),
+            ModuleDef::Variant(it) => it.visibility(db),
+            ModuleDef::Macro(it) => it.visibility(db),
+            ModuleDef::BuiltinType(_) => Visibility::Public,
+        }
+    }
+}
+
+impl Module {
+    /// Name of this module.
+    pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
+        let def_map = self.id.def_map(db.upcast());
+        let parent = def_map[self.id.local_id].parent?;
+        def_map[parent].children.iter().find_map(|(name, module_id)| {
+            if *module_id == self.id.local_id {
+                Some(name.clone())
+            } else {
+                None
+            }
+        })
+    }
+
+    /// Returns the crate this module is part of.
+    pub fn krate(self) -> Crate {
+        Crate { id: self.id.krate() }
+    }
+
+    /// Topmost parent of this module. Every module has a `crate_root`, but some
+    /// might be missing `krate`. This can happen if a module's file is not included
+    /// in the module tree of any target in `Cargo.toml`.
+    pub fn crate_root(self, db: &dyn HirDatabase) -> Module {
+        let def_map = db.crate_def_map(self.id.krate());
+        Module { id: def_map.module_id(def_map.root()) }
+    }
+
+    pub fn is_crate_root(self, db: &dyn HirDatabase) -> bool {
+        let def_map = db.crate_def_map(self.id.krate());
+        def_map.root() == self.id.local_id
+    }
+
+    /// Iterates over all child modules.
+    pub fn children(self, db: &dyn HirDatabase) -> impl Iterator<Item = Module> {
+        let def_map = self.id.def_map(db.upcast());
+        let children = def_map[self.id.local_id]
+            .children
+            .iter()
+            .map(|(_, module_id)| Module { id: def_map.module_id(*module_id) })
+            .collect::<Vec<_>>();
+        children.into_iter()
+    }
+
+    /// Finds a parent module.
+    pub fn parent(self, db: &dyn HirDatabase) -> Option<Module> {
+        // FIXME: handle block expressions as modules (their parent is in a different DefMap)
+        let def_map = self.id.def_map(db.upcast());
+        let parent_id = def_map[self.id.local_id].parent?;
+        Some(Module { id: def_map.module_id(parent_id) })
+    }
+
+    pub fn path_to_root(self, db: &dyn HirDatabase) -> Vec<Module> {
+        let mut res = vec![self];
+        let mut curr = self;
+        while let Some(next) = curr.parent(db) {
+            res.push(next);
+            curr = next
+        }
+        res
+    }
+
+    /// Returns a `ModuleScope`: a set of items, visible in this module.
+    pub fn scope(
+        self,
+        db: &dyn HirDatabase,
+        visible_from: Option<Module>,
+    ) -> Vec<(Name, ScopeDef)> {
+        self.id.def_map(db.upcast())[self.id.local_id]
+            .scope
+            .entries()
+            .filter_map(|(name, def)| {
+                if let Some(m) = visible_from {
+                    let filtered =
+                        def.filter_visibility(|vis| vis.is_visible_from(db.upcast(), m.id));
+                    if filtered.is_none() && !def.is_none() {
+                        None
+                    } else {
+                        Some((name, filtered))
+                    }
+                } else {
+                    Some((name, def))
+                }
+            })
+            .flat_map(|(name, def)| {
+                ScopeDef::all_items(def).into_iter().map(move |item| (name.clone(), item))
+            })
+            .collect()
+    }
+
+    pub fn diagnostics(self, db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>) {
+        let _p = profile::span("Module::diagnostics").detail(|| {
+            format!("{:?}", self.name(db).map_or("<unknown>".into(), |name| name.to_string()))
+        });
+        let def_map = self.id.def_map(db.upcast());
+        for diag in def_map.diagnostics() {
+            if diag.in_module != self.id.local_id {
+                // FIXME: This is accidentally quadratic.
+                continue;
+            }
+            emit_def_diagnostic(db, acc, diag);
+        }
+        for decl in self.declarations(db) {
+            match decl {
+                ModuleDef::Module(m) => {
+                    // Only add diagnostics from inline modules
+                    if def_map[m.id.local_id].origin.is_inline() {
+                        m.diagnostics(db, acc)
+                    }
+                }
+                _ => acc.extend(decl.diagnostics(db)),
+            }
+        }
+
+        for impl_def in self.impl_defs(db) {
+            for item in impl_def.items(db) {
+                let def: DefWithBody = match item {
+                    AssocItem::Function(it) => it.into(),
+                    AssocItem::Const(it) => it.into(),
+                    AssocItem::TypeAlias(_) => continue,
+                };
+
+                def.diagnostics(db, acc);
+            }
+        }
+    }
+
+    pub fn declarations(self, db: &dyn HirDatabase) -> Vec<ModuleDef> {
+        let def_map = self.id.def_map(db.upcast());
+        let scope = &def_map[self.id.local_id].scope;
+        scope
+            .declarations()
+            .map(ModuleDef::from)
+            .chain(scope.unnamed_consts().map(|id| ModuleDef::Const(Const::from(id))))
+            .collect()
+    }
+
+    pub fn legacy_macros(self, db: &dyn HirDatabase) -> Vec<Macro> {
+        let def_map = self.id.def_map(db.upcast());
+        let scope = &def_map[self.id.local_id].scope;
+        scope.legacy_macros().flat_map(|(_, it)| it).map(|&it| MacroId::from(it).into()).collect()
+    }
+
+    pub fn impl_defs(self, db: &dyn HirDatabase) -> Vec<Impl> {
+        let def_map = self.id.def_map(db.upcast());
+        def_map[self.id.local_id].scope.impls().map(Impl::from).collect()
+    }
+
+    /// Finds a path that can be used to refer to the given item from within
+    /// this module, if possible.
+    pub fn find_use_path(self, db: &dyn DefDatabase, item: impl Into<ItemInNs>) -> Option<ModPath> {
+        hir_def::find_path::find_path(db, item.into().into(), self.into())
+    }
+
+    /// Finds a path that can be used to refer to the given item from within
+    /// this module, if possible. This is used for returning import paths for use-statements.
+    pub fn find_use_path_prefixed(
+        self,
+        db: &dyn DefDatabase,
+        item: impl Into<ItemInNs>,
+        prefix_kind: PrefixKind,
+    ) -> Option<ModPath> {
+        hir_def::find_path::find_path_prefixed(db, item.into().into(), self.into(), prefix_kind)
+    }
+}
+
+fn emit_def_diagnostic(db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>, diag: &DefDiagnostic) {
+    match &diag.kind {
+        DefDiagnosticKind::UnresolvedModule { ast: declaration, candidates } => {
+            let decl = declaration.to_node(db.upcast());
+            acc.push(
+                UnresolvedModule {
+                    decl: InFile::new(declaration.file_id, AstPtr::new(&decl)),
+                    candidates: candidates.clone(),
+                }
+                .into(),
+            )
+        }
+        DefDiagnosticKind::UnresolvedExternCrate { ast } => {
+            let item = ast.to_node(db.upcast());
+            acc.push(
+                UnresolvedExternCrate { decl: InFile::new(ast.file_id, AstPtr::new(&item)) }.into(),
+            );
+        }
+
+        DefDiagnosticKind::UnresolvedImport { id, index } => {
+            let file_id = id.file_id();
+            let item_tree = id.item_tree(db.upcast());
+            let import = &item_tree[id.value];
+
+            let use_tree = import.use_tree_to_ast(db.upcast(), file_id, *index);
+            acc.push(
+                UnresolvedImport { decl: InFile::new(file_id, AstPtr::new(&use_tree)) }.into(),
+            );
+        }
+
+        DefDiagnosticKind::UnconfiguredCode { ast, cfg, opts } => {
+            let item = ast.to_node(db.upcast());
+            acc.push(
+                InactiveCode {
+                    node: ast.with_value(AstPtr::new(&item).into()),
+                    cfg: cfg.clone(),
+                    opts: opts.clone(),
+                }
+                .into(),
+            );
+        }
+
+        DefDiagnosticKind::UnresolvedProcMacro { ast, krate } => {
+            let (node, precise_location, macro_name, kind) = precise_macro_call_location(ast, db);
+            acc.push(
+                UnresolvedProcMacro { node, precise_location, macro_name, kind, krate: *krate }
+                    .into(),
+            );
+        }
+
+        DefDiagnosticKind::UnresolvedMacroCall { ast, path } => {
+            let (node, precise_location, _, _) = precise_macro_call_location(ast, db);
+            acc.push(
+                UnresolvedMacroCall {
+                    macro_call: node,
+                    precise_location,
+                    path: path.clone(),
+                    is_bang: matches!(ast, MacroCallKind::FnLike { .. }),
+                }
+                .into(),
+            );
+        }
+
+        DefDiagnosticKind::MacroError { ast, message } => {
+            let (node, precise_location, _, _) = precise_macro_call_location(ast, db);
+            acc.push(MacroError { node, precise_location, message: message.clone() }.into());
+        }
+
+        DefDiagnosticKind::UnimplementedBuiltinMacro { ast } => {
+            let node = ast.to_node(db.upcast());
+            // Must have a name, otherwise we wouldn't emit it.
+            let name = node.name().expect("unimplemented builtin macro with no name");
+            acc.push(
+                UnimplementedBuiltinMacro {
+                    node: ast.with_value(SyntaxNodePtr::from(AstPtr::new(&name))),
+                }
+                .into(),
+            );
+        }
+        DefDiagnosticKind::InvalidDeriveTarget { ast, id } => {
+            let node = ast.to_node(db.upcast());
+            let derive = node.attrs().nth(*id as usize);
+            match derive {
+                Some(derive) => {
+                    acc.push(
+                        InvalidDeriveTarget {
+                            node: ast.with_value(SyntaxNodePtr::from(AstPtr::new(&derive))),
+                        }
+                        .into(),
+                    );
+                }
+                None => stdx::never!("derive diagnostic on item without derive attribute"),
+            }
+        }
+        DefDiagnosticKind::MalformedDerive { ast, id } => {
+            let node = ast.to_node(db.upcast());
+            let derive = node.attrs().nth(*id as usize);
+            match derive {
+                Some(derive) => {
+                    acc.push(
+                        MalformedDerive {
+                            node: ast.with_value(SyntaxNodePtr::from(AstPtr::new(&derive))),
+                        }
+                        .into(),
+                    );
+                }
+                None => stdx::never!("derive diagnostic on item without derive attribute"),
+            }
+        }
+    }
+}
+
+fn precise_macro_call_location(
+    ast: &MacroCallKind,
+    db: &dyn HirDatabase,
+) -> (InFile<SyntaxNodePtr>, Option<TextRange>, Option<String>, MacroKind) {
+    // FIXME: maaybe we actually want slightly different ranges for the different macro diagnostics
+    // - e.g. the full attribute for macro errors, but only the name for name resolution
+    match ast {
+        MacroCallKind::FnLike { ast_id, .. } => {
+            let node = ast_id.to_node(db.upcast());
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
+                node.path()
+                    .and_then(|it| it.segment())
+                    .and_then(|it| it.name_ref())
+                    .map(|it| it.syntax().text_range()),
+                node.path().and_then(|it| it.segment()).map(|it| it.to_string()),
+                MacroKind::ProcMacro,
+            )
+        }
+        MacroCallKind::Derive { ast_id, derive_attr_index, derive_index } => {
+            let node = ast_id.to_node(db.upcast());
+            // Compute the precise location of the macro name's token in the derive
+            // list.
+            let token = (|| {
+                let derive_attr = node
+                    .doc_comments_and_attrs()
+                    .nth(*derive_attr_index as usize)
+                    .and_then(Either::left)?;
+                let token_tree = derive_attr.meta()?.token_tree()?;
+                let group_by = token_tree
+                    .syntax()
+                    .children_with_tokens()
+                    .filter_map(|elem| match elem {
+                        syntax::NodeOrToken::Token(tok) => Some(tok),
+                        _ => None,
+                    })
+                    .group_by(|t| t.kind() == T![,]);
+                let (_, mut group) = group_by
+                    .into_iter()
+                    .filter(|&(comma, _)| !comma)
+                    .nth(*derive_index as usize)?;
+                group.find(|t| t.kind() == T![ident])
+            })();
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
+                token.as_ref().map(|tok| tok.text_range()),
+                token.as_ref().map(ToString::to_string),
+                MacroKind::Derive,
+            )
+        }
+        MacroCallKind::Attr { ast_id, invoc_attr_index, .. } => {
+            let node = ast_id.to_node(db.upcast());
+            let attr = node
+                .doc_comments_and_attrs()
+                .nth((*invoc_attr_index) as usize)
+                .and_then(Either::left)
+                .unwrap_or_else(|| panic!("cannot find attribute #{}", invoc_attr_index));
+
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&attr))),
+                Some(attr.syntax().text_range()),
+                attr.path()
+                    .and_then(|path| path.segment())
+                    .and_then(|seg| seg.name_ref())
+                    .as_ref()
+                    .map(ToString::to_string),
+                MacroKind::Attr,
+            )
+        }
+    }
+}
+
+impl HasVisibility for Module {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        let def_map = self.id.def_map(db.upcast());
+        let module_data = &def_map[self.id.local_id];
+        module_data.visibility
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Field {
+    pub(crate) parent: VariantDef,
+    pub(crate) id: LocalFieldId,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum FieldSource {
+    Named(ast::RecordField),
+    Pos(ast::TupleField),
+}
+
+impl Field {
+    pub fn name(&self, db: &dyn HirDatabase) -> Name {
+        self.parent.variant_data(db).fields()[self.id].name.clone()
+    }
+
+    /// Returns the type as in the signature of the struct (i.e., with
+    /// placeholder types for type parameters). Only use this in the context of
+    /// the field definition.
+    pub fn ty(&self, db: &dyn HirDatabase) -> Type {
+        let var_id = self.parent.into();
+        let generic_def_id: GenericDefId = match self.parent {
+            VariantDef::Struct(it) => it.id.into(),
+            VariantDef::Union(it) => it.id.into(),
+            VariantDef::Variant(it) => it.parent.id.into(),
+        };
+        let substs = TyBuilder::placeholder_subst(db, generic_def_id);
+        let ty = db.field_types(var_id)[self.id].clone().substitute(Interner, &substs);
+        Type::new(db, var_id, ty)
+    }
+
+    pub fn parent_def(&self, _db: &dyn HirDatabase) -> VariantDef {
+        self.parent
+    }
+}
+
+impl HasVisibility for Field {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        let variant_data = self.parent.variant_data(db);
+        let visibility = &variant_data.fields()[self.id].visibility;
+        let parent_id: hir_def::VariantId = self.parent.into();
+        visibility.resolve(db.upcast(), &parent_id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Struct {
+    pub(crate) id: StructId,
+}
+
+impl Struct {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).container }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.struct_data(self.id).name.clone()
+    }
+
+    pub fn fields(self, db: &dyn HirDatabase) -> Vec<Field> {
+        db.struct_data(self.id)
+            .variant_data
+            .fields()
+            .iter()
+            .map(|(id, _)| Field { parent: self.into(), id })
+            .collect()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::from_def(db, self.id)
+    }
+
+    pub fn repr(self, db: &dyn HirDatabase) -> Option<ReprKind> {
+        db.struct_data(self.id).repr.clone()
+    }
+
+    pub fn kind(self, db: &dyn HirDatabase) -> StructKind {
+        self.variant_data(db).kind()
+    }
+
+    fn variant_data(self, db: &dyn HirDatabase) -> Arc<VariantData> {
+        db.struct_data(self.id).variant_data.clone()
+    }
+}
+
+impl HasVisibility for Struct {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.struct_data(self.id).visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Union {
+    pub(crate) id: UnionId,
+}
+
+impl Union {
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.union_data(self.id).name.clone()
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).container }
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::from_def(db, self.id)
+    }
+
+    pub fn fields(self, db: &dyn HirDatabase) -> Vec<Field> {
+        db.union_data(self.id)
+            .variant_data
+            .fields()
+            .iter()
+            .map(|(id, _)| Field { parent: self.into(), id })
+            .collect()
+    }
+
+    fn variant_data(self, db: &dyn HirDatabase) -> Arc<VariantData> {
+        db.union_data(self.id).variant_data.clone()
+    }
+}
+
+impl HasVisibility for Union {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.union_data(self.id).visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Enum {
+    pub(crate) id: EnumId,
+}
+
+impl Enum {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).container }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.enum_data(self.id).name.clone()
+    }
+
+    pub fn variants(self, db: &dyn HirDatabase) -> Vec<Variant> {
+        db.enum_data(self.id).variants.iter().map(|(id, _)| Variant { parent: self, id }).collect()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::from_def(db, self.id)
+    }
+}
+
+impl HasVisibility for Enum {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.enum_data(self.id).visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Variant {
+    pub(crate) parent: Enum,
+    pub(crate) id: LocalEnumVariantId,
+}
+
+impl Variant {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.parent.module(db)
+    }
+
+    pub fn parent_enum(self, _db: &dyn HirDatabase) -> Enum {
+        self.parent
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.enum_data(self.parent.id).variants[self.id].name.clone()
+    }
+
+    pub fn fields(self, db: &dyn HirDatabase) -> Vec<Field> {
+        self.variant_data(db)
+            .fields()
+            .iter()
+            .map(|(id, _)| Field { parent: self.into(), id })
+            .collect()
+    }
+
+    pub fn kind(self, db: &dyn HirDatabase) -> StructKind {
+        self.variant_data(db).kind()
+    }
+
+    pub(crate) fn variant_data(self, db: &dyn HirDatabase) -> Arc<VariantData> {
+        db.enum_data(self.parent.id).variants[self.id].variant_data.clone()
+    }
+}
+
+/// Variants inherit visibility from the parent enum.
+impl HasVisibility for Variant {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        self.parent_enum(db).visibility(db)
+    }
+}
+
+/// A Data Type
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum Adt {
+    Struct(Struct),
+    Union(Union),
+    Enum(Enum),
+}
+impl_from!(Struct, Union, Enum for Adt);
+
+impl Adt {
+    pub fn has_non_default_type_params(self, db: &dyn HirDatabase) -> bool {
+        let subst = db.generic_defaults(self.into());
+        subst.iter().any(|ty| match ty.skip_binders().data(Interner) {
+            GenericArgData::Ty(x) => x.is_unknown(),
+            _ => false,
+        })
+    }
+
+    /// Turns this ADT into a type. Any type parameters of the ADT will be
+    /// turned into unknown types, which is good for e.g. finding the most
+    /// general set of completions, but will not look very nice when printed.
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let id = AdtId::from(self);
+        Type::from_def(db, id)
+    }
+
+    /// Turns this ADT into a type with the given type parameters. This isn't
+    /// the greatest API, FIXME find a better one.
+    pub fn ty_with_args(self, db: &dyn HirDatabase, args: &[Type]) -> Type {
+        let id = AdtId::from(self);
+        let mut it = args.iter().map(|t| t.ty.clone());
+        let ty = TyBuilder::def_ty(db, id.into())
+            .fill(|x| {
+                let r = it.next().unwrap_or_else(|| TyKind::Error.intern(Interner));
+                match x {
+                    ParamKind::Type => GenericArgData::Ty(r).intern(Interner),
+                    ParamKind::Const(ty) => unknown_const_as_generic(ty.clone()),
+                }
+            })
+            .build();
+        Type::new(db, id, ty)
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        match self {
+            Adt::Struct(s) => s.module(db),
+            Adt::Union(s) => s.module(db),
+            Adt::Enum(e) => e.module(db),
+        }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        match self {
+            Adt::Struct(s) => s.name(db),
+            Adt::Union(u) => u.name(db),
+            Adt::Enum(e) => e.name(db),
+        }
+    }
+
+    pub fn as_enum(&self) -> Option<Enum> {
+        if let Self::Enum(v) = self {
+            Some(*v)
+        } else {
+            None
+        }
+    }
+}
+
+impl HasVisibility for Adt {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        match self {
+            Adt::Struct(it) => it.visibility(db),
+            Adt::Union(it) => it.visibility(db),
+            Adt::Enum(it) => it.visibility(db),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum VariantDef {
+    Struct(Struct),
+    Union(Union),
+    Variant(Variant),
+}
+impl_from!(Struct, Union, Variant for VariantDef);
+
+impl VariantDef {
+    pub fn fields(self, db: &dyn HirDatabase) -> Vec<Field> {
+        match self {
+            VariantDef::Struct(it) => it.fields(db),
+            VariantDef::Union(it) => it.fields(db),
+            VariantDef::Variant(it) => it.fields(db),
+        }
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        match self {
+            VariantDef::Struct(it) => it.module(db),
+            VariantDef::Union(it) => it.module(db),
+            VariantDef::Variant(it) => it.module(db),
+        }
+    }
+
+    pub fn name(&self, db: &dyn HirDatabase) -> Name {
+        match self {
+            VariantDef::Struct(s) => s.name(db),
+            VariantDef::Union(u) => u.name(db),
+            VariantDef::Variant(e) => e.name(db),
+        }
+    }
+
+    pub(crate) fn variant_data(self, db: &dyn HirDatabase) -> Arc<VariantData> {
+        match self {
+            VariantDef::Struct(it) => it.variant_data(db),
+            VariantDef::Union(it) => it.variant_data(db),
+            VariantDef::Variant(it) => it.variant_data(db),
+        }
+    }
+}
+
+/// The defs which have a body.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum DefWithBody {
+    Function(Function),
+    Static(Static),
+    Const(Const),
+}
+impl_from!(Function, Const, Static for DefWithBody);
+
+impl DefWithBody {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        match self {
+            DefWithBody::Const(c) => c.module(db),
+            DefWithBody::Function(f) => f.module(db),
+            DefWithBody::Static(s) => s.module(db),
+        }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
+        match self {
+            DefWithBody::Function(f) => Some(f.name(db)),
+            DefWithBody::Static(s) => Some(s.name(db)),
+            DefWithBody::Const(c) => c.name(db),
+        }
+    }
+
+    /// Returns the type this def's body has to evaluate to.
+    pub fn body_type(self, db: &dyn HirDatabase) -> Type {
+        match self {
+            DefWithBody::Function(it) => it.ret_type(db),
+            DefWithBody::Static(it) => it.ty(db),
+            DefWithBody::Const(it) => it.ty(db),
+        }
+    }
+
+    pub fn diagnostics(self, db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>) {
+        let krate = self.module(db).id.krate();
+
+        let (body, source_map) = db.body_with_source_map(self.into());
+
+        for (_, def_map) in body.blocks(db.upcast()) {
+            for diag in def_map.diagnostics() {
+                emit_def_diagnostic(db, acc, diag);
+            }
+        }
+
+        for diag in source_map.diagnostics() {
+            match diag {
+                BodyDiagnostic::InactiveCode { node, cfg, opts } => acc.push(
+                    InactiveCode { node: node.clone(), cfg: cfg.clone(), opts: opts.clone() }
+                        .into(),
+                ),
+                BodyDiagnostic::MacroError { node, message } => acc.push(
+                    MacroError {
+                        node: node.clone().map(|it| it.into()),
+                        precise_location: None,
+                        message: message.to_string(),
+                    }
+                    .into(),
+                ),
+                BodyDiagnostic::UnresolvedProcMacro { node, krate } => acc.push(
+                    UnresolvedProcMacro {
+                        node: node.clone().map(|it| it.into()),
+                        precise_location: None,
+                        macro_name: None,
+                        kind: MacroKind::ProcMacro,
+                        krate: *krate,
+                    }
+                    .into(),
+                ),
+                BodyDiagnostic::UnresolvedMacroCall { node, path } => acc.push(
+                    UnresolvedMacroCall {
+                        macro_call: node.clone().map(|ast_ptr| ast_ptr.into()),
+                        precise_location: None,
+                        path: path.clone(),
+                        is_bang: true,
+                    }
+                    .into(),
+                ),
+            }
+        }
+
+        let infer = db.infer(self.into());
+        let source_map = Lazy::new(|| db.body_with_source_map(self.into()).1);
+        for d in &infer.diagnostics {
+            match d {
+                hir_ty::InferenceDiagnostic::NoSuchField { expr } => {
+                    let field = source_map.field_syntax(*expr);
+                    acc.push(NoSuchField { field }.into())
+                }
+                hir_ty::InferenceDiagnostic::BreakOutsideOfLoop { expr } => {
+                    let expr = source_map
+                        .expr_syntax(*expr)
+                        .expect("break outside of loop in synthetic syntax");
+                    acc.push(BreakOutsideOfLoop { expr }.into())
+                }
+                hir_ty::InferenceDiagnostic::MismatchedArgCount { call_expr, expected, found } => {
+                    match source_map.expr_syntax(*call_expr) {
+                        Ok(source_ptr) => acc.push(
+                            MismatchedArgCount {
+                                call_expr: source_ptr,
+                                expected: *expected,
+                                found: *found,
+                            }
+                            .into(),
+                        ),
+                        Err(SyntheticSyntax) => (),
+                    }
+                }
+            }
+        }
+        for (expr, mismatch) in infer.expr_type_mismatches() {
+            let expr = match source_map.expr_syntax(expr) {
+                Ok(expr) => expr,
+                Err(SyntheticSyntax) => continue,
+            };
+            acc.push(
+                TypeMismatch {
+                    expr,
+                    expected: Type::new(db, DefWithBodyId::from(self), mismatch.expected.clone()),
+                    actual: Type::new(db, DefWithBodyId::from(self), mismatch.actual.clone()),
+                }
+                .into(),
+            );
+        }
+
+        for expr in hir_ty::diagnostics::missing_unsafe(db, self.into()) {
+            match source_map.expr_syntax(expr) {
+                Ok(expr) => acc.push(MissingUnsafe { expr }.into()),
+                Err(SyntheticSyntax) => {
+                    // FIXME: Here and eslwhere in this file, the `expr` was
+                    // desugared, report or assert that this doesn't happen.
+                }
+            }
+        }
+
+        for diagnostic in BodyValidationDiagnostic::collect(db, self.into()) {
+            match diagnostic {
+                BodyValidationDiagnostic::RecordMissingFields {
+                    record,
+                    variant,
+                    missed_fields,
+                } => {
+                    let variant_data = variant.variant_data(db.upcast());
+                    let missed_fields = missed_fields
+                        .into_iter()
+                        .map(|idx| variant_data.fields()[idx].name.clone())
+                        .collect();
+
+                    match record {
+                        Either::Left(record_expr) => match source_map.expr_syntax(record_expr) {
+                            Ok(source_ptr) => {
+                                let root = source_ptr.file_syntax(db.upcast());
+                                if let ast::Expr::RecordExpr(record_expr) =
+                                    &source_ptr.value.to_node(&root)
+                                {
+                                    if record_expr.record_expr_field_list().is_some() {
+                                        acc.push(
+                                            MissingFields {
+                                                file: source_ptr.file_id,
+                                                field_list_parent: Either::Left(AstPtr::new(
+                                                    record_expr,
+                                                )),
+                                                field_list_parent_path: record_expr
+                                                    .path()
+                                                    .map(|path| AstPtr::new(&path)),
+                                                missed_fields,
+                                            }
+                                            .into(),
+                                        )
+                                    }
+                                }
+                            }
+                            Err(SyntheticSyntax) => (),
+                        },
+                        Either::Right(record_pat) => match source_map.pat_syntax(record_pat) {
+                            Ok(source_ptr) => {
+                                if let Some(expr) = source_ptr.value.as_ref().left() {
+                                    let root = source_ptr.file_syntax(db.upcast());
+                                    if let ast::Pat::RecordPat(record_pat) = expr.to_node(&root) {
+                                        if record_pat.record_pat_field_list().is_some() {
+                                            acc.push(
+                                                MissingFields {
+                                                    file: source_ptr.file_id,
+                                                    field_list_parent: Either::Right(AstPtr::new(
+                                                        &record_pat,
+                                                    )),
+                                                    field_list_parent_path: record_pat
+                                                        .path()
+                                                        .map(|path| AstPtr::new(&path)),
+                                                    missed_fields,
+                                                }
+                                                .into(),
+                                            )
+                                        }
+                                    }
+                                }
+                            }
+                            Err(SyntheticSyntax) => (),
+                        },
+                    }
+                }
+                BodyValidationDiagnostic::ReplaceFilterMapNextWithFindMap { method_call_expr } => {
+                    if let Ok(next_source_ptr) = source_map.expr_syntax(method_call_expr) {
+                        acc.push(
+                            ReplaceFilterMapNextWithFindMap {
+                                file: next_source_ptr.file_id,
+                                next_expr: next_source_ptr.value,
+                            }
+                            .into(),
+                        );
+                    }
+                }
+                BodyValidationDiagnostic::MissingMatchArms { match_expr, uncovered_patterns } => {
+                    match source_map.expr_syntax(match_expr) {
+                        Ok(source_ptr) => {
+                            let root = source_ptr.file_syntax(db.upcast());
+                            if let ast::Expr::MatchExpr(match_expr) =
+                                &source_ptr.value.to_node(&root)
+                            {
+                                if let Some(match_expr) = match_expr.expr() {
+                                    acc.push(
+                                        MissingMatchArms {
+                                            file: source_ptr.file_id,
+                                            match_expr: AstPtr::new(&match_expr),
+                                            uncovered_patterns,
+                                        }
+                                        .into(),
+                                    );
+                                }
+                            }
+                        }
+                        Err(SyntheticSyntax) => (),
+                    }
+                }
+            }
+        }
+
+        let def: ModuleDef = match self {
+            DefWithBody::Function(it) => it.into(),
+            DefWithBody::Static(it) => it.into(),
+            DefWithBody::Const(it) => it.into(),
+        };
+        for diag in hir_ty::diagnostics::incorrect_case(db, krate, def.into()) {
+            acc.push(diag.into())
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Function {
+    pub(crate) id: FunctionId,
+}
+
+impl Function {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.lookup(db.upcast()).module(db.upcast()).into()
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.function_data(self.id).name.clone()
+    }
+
+    /// Get this function's return type
+    pub fn ret_type(self, db: &dyn HirDatabase) -> Type {
+        let resolver = self.id.resolver(db.upcast());
+        let substs = TyBuilder::placeholder_subst(db, self.id);
+        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let ty = callable_sig.ret().clone();
+        Type::new_with_resolver_inner(db, &resolver, ty)
+    }
+
+    pub fn async_ret_type(self, db: &dyn HirDatabase) -> Option<Type> {
+        if !self.is_async(db) {
+            return None;
+        }
+        let resolver = self.id.resolver(db.upcast());
+        let substs = TyBuilder::placeholder_subst(db, self.id);
+        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let ret_ty = callable_sig.ret().clone();
+        for pred in ret_ty.impl_trait_bounds(db).into_iter().flatten() {
+            if let WhereClause::AliasEq(output_eq) = pred.into_value_and_skipped_binders().0 {
+                return Type::new_with_resolver_inner(db, &resolver, output_eq.ty).into();
+            }
+        }
+        never!("Async fn ret_type should be impl Future");
+        None
+    }
+
+    pub fn has_self_param(self, db: &dyn HirDatabase) -> bool {
+        db.function_data(self.id).has_self_param()
+    }
+
+    pub fn self_param(self, db: &dyn HirDatabase) -> Option<SelfParam> {
+        self.has_self_param(db).then(|| SelfParam { func: self.id })
+    }
+
+    pub fn assoc_fn_params(self, db: &dyn HirDatabase) -> Vec<Param> {
+        let environment = db.trait_environment(self.id.into());
+        let substs = TyBuilder::placeholder_subst(db, self.id);
+        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        callable_sig
+            .params()
+            .iter()
+            .enumerate()
+            .map(|(idx, ty)| {
+                let ty = Type { env: environment.clone(), ty: ty.clone() };
+                Param { func: self, ty, idx }
+            })
+            .collect()
+    }
+
+    pub fn method_params(self, db: &dyn HirDatabase) -> Option<Vec<Param>> {
+        if self.self_param(db).is_none() {
+            return None;
+        }
+        Some(self.params_without_self(db))
+    }
+
+    pub fn params_without_self(self, db: &dyn HirDatabase) -> Vec<Param> {
+        let environment = db.trait_environment(self.id.into());
+        let substs = TyBuilder::placeholder_subst(db, self.id);
+        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let skip = if db.function_data(self.id).has_self_param() { 1 } else { 0 };
+        callable_sig
+            .params()
+            .iter()
+            .enumerate()
+            .skip(skip)
+            .map(|(idx, ty)| {
+                let ty = Type { env: environment.clone(), ty: ty.clone() };
+                Param { func: self, ty, idx }
+            })
+            .collect()
+    }
+
+    pub fn is_const(self, db: &dyn HirDatabase) -> bool {
+        db.function_data(self.id).has_const_kw()
+    }
+
+    pub fn is_async(self, db: &dyn HirDatabase) -> bool {
+        db.function_data(self.id).has_async_kw()
+    }
+
+    pub fn is_unsafe_to_call(self, db: &dyn HirDatabase) -> bool {
+        hir_ty::is_fn_unsafe_to_call(db, self.id)
+    }
+
+    /// Whether this function declaration has a definition.
+    ///
+    /// This is false in the case of required (not provided) trait methods.
+    pub fn has_body(self, db: &dyn HirDatabase) -> bool {
+        db.function_data(self.id).has_body()
+    }
+
+    pub fn as_proc_macro(self, db: &dyn HirDatabase) -> Option<Macro> {
+        let function_data = db.function_data(self.id);
+        let attrs = &function_data.attrs;
+        // FIXME: Store this in FunctionData flags?
+        if !(attrs.is_proc_macro()
+            || attrs.is_proc_macro_attribute()
+            || attrs.is_proc_macro_derive())
+        {
+            return None;
+        }
+        let loc = self.id.lookup(db.upcast());
+        let def_map = db.crate_def_map(loc.krate(db).into());
+        def_map.fn_as_proc_macro(self.id).map(|id| Macro { id: id.into() })
+    }
+
+    /// A textual representation of the HIR of this function for debugging purposes.
+    pub fn debug_hir(self, db: &dyn HirDatabase) -> String {
+        let body = db.body(self.id.into());
+
+        let mut result = String::new();
+        format_to!(result, "HIR expressions in the body of `{}`:\n", self.name(db));
+        for (id, expr) in body.exprs.iter() {
+            format_to!(result, "{:?}: {:?}\n", id, expr);
+        }
+
+        result
+    }
+}
+
+// Note: logically, this belongs to `hir_ty`, but we are not using it there yet.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum Access {
+    Shared,
+    Exclusive,
+    Owned,
+}
+
+impl From<hir_ty::Mutability> for Access {
+    fn from(mutability: hir_ty::Mutability) -> Access {
+        match mutability {
+            hir_ty::Mutability::Not => Access::Shared,
+            hir_ty::Mutability::Mut => Access::Exclusive,
+        }
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct Param {
+    func: Function,
+    /// The index in parameter list, including self parameter.
+    idx: usize,
+    ty: Type,
+}
+
+impl Param {
+    pub fn ty(&self) -> &Type {
+        &self.ty
+    }
+
+    pub fn name(&self, db: &dyn HirDatabase) -> Option<Name> {
+        db.function_data(self.func.id).params[self.idx].0.clone()
+    }
+
+    pub fn as_local(&self, db: &dyn HirDatabase) -> Option<Local> {
+        let parent = DefWithBodyId::FunctionId(self.func.into());
+        let body = db.body(parent);
+        let pat_id = body.params[self.idx];
+        if let Pat::Bind { .. } = &body[pat_id] {
+            Some(Local { parent, pat_id: body.params[self.idx] })
+        } else {
+            None
+        }
+    }
+
+    pub fn pattern_source(&self, db: &dyn HirDatabase) -> Option<ast::Pat> {
+        self.source(db).and_then(|p| p.value.pat())
+    }
+
+    pub fn source(&self, db: &dyn HirDatabase) -> Option<InFile<ast::Param>> {
+        let InFile { file_id, value } = self.func.source(db)?;
+        let params = value.param_list()?;
+        if params.self_param().is_some() {
+            params.params().nth(self.idx.checked_sub(1)?)
+        } else {
+            params.params().nth(self.idx)
+        }
+        .map(|value| InFile { file_id, value })
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct SelfParam {
+    func: FunctionId,
+}
+
+impl SelfParam {
+    pub fn access(self, db: &dyn HirDatabase) -> Access {
+        let func_data = db.function_data(self.func);
+        func_data
+            .params
+            .first()
+            .map(|(_, param)| match &**param {
+                TypeRef::Reference(.., mutability) => match mutability {
+                    hir_def::type_ref::Mutability::Shared => Access::Shared,
+                    hir_def::type_ref::Mutability::Mut => Access::Exclusive,
+                },
+                _ => Access::Owned,
+            })
+            .unwrap_or(Access::Owned)
+    }
+
+    pub fn display(self, db: &dyn HirDatabase) -> &'static str {
+        match self.access(db) {
+            Access::Shared => "&self",
+            Access::Exclusive => "&mut self",
+            Access::Owned => "self",
+        }
+    }
+
+    pub fn source(&self, db: &dyn HirDatabase) -> Option<InFile<ast::SelfParam>> {
+        let InFile { file_id, value } = Function::from(self.func).source(db)?;
+        value
+            .param_list()
+            .and_then(|params| params.self_param())
+            .map(|value| InFile { file_id, value })
+    }
+
+    pub fn ty(&self, db: &dyn HirDatabase) -> Type {
+        let substs = TyBuilder::placeholder_subst(db, self.func);
+        let callable_sig =
+            db.callable_item_signature(self.func.into()).substitute(Interner, &substs);
+        let environment = db.trait_environment(self.func.into());
+        let ty = callable_sig.params()[0].clone();
+        Type { env: environment, ty }
+    }
+}
+
+impl HasVisibility for Function {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.function_visibility(self.id)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Const {
+    pub(crate) id: ConstId,
+}
+
+impl Const {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
+        db.const_data(self.id).name.clone()
+    }
+
+    pub fn value(self, db: &dyn HirDatabase) -> Option<ast::Expr> {
+        self.source(db)?.value.body()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let data = db.const_data(self.id);
+        let resolver = self.id.resolver(db.upcast());
+        let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
+        let ty = ctx.lower_ty(&data.type_ref);
+        Type::new_with_resolver_inner(db, &resolver, ty)
+    }
+
+    pub fn eval(self, db: &dyn HirDatabase) -> Result<ComputedExpr, ConstEvalError> {
+        db.const_eval(self.id)
+    }
+}
+
+impl HasVisibility for Const {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.const_visibility(self.id)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Static {
+    pub(crate) id: StaticId,
+}
+
+impl Static {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.static_data(self.id).name.clone()
+    }
+
+    pub fn is_mut(self, db: &dyn HirDatabase) -> bool {
+        db.static_data(self.id).mutable
+    }
+
+    pub fn value(self, db: &dyn HirDatabase) -> Option<ast::Expr> {
+        self.source(db)?.value.body()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let data = db.static_data(self.id);
+        let resolver = self.id.resolver(db.upcast());
+        let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
+        let ty = ctx.lower_ty(&data.type_ref);
+        Type::new_with_resolver_inner(db, &resolver, ty)
+    }
+}
+
+impl HasVisibility for Static {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.static_data(self.id).visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Trait {
+    pub(crate) id: TraitId,
+}
+
+impl Trait {
+    pub fn lang(db: &dyn HirDatabase, krate: Crate, name: &Name) -> Option<Trait> {
+        db.lang_item(krate.into(), name.to_smol_str())
+            .and_then(LangItemTarget::as_trait)
+            .map(Into::into)
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).container }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.trait_data(self.id).name.clone()
+    }
+
+    pub fn items(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
+        db.trait_data(self.id).items.iter().map(|(_name, it)| (*it).into()).collect()
+    }
+
+    pub fn items_with_supertraits(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
+        let traits = all_super_traits(db.upcast(), self.into());
+        traits.iter().flat_map(|tr| Trait::from(*tr).items(db)).collect()
+    }
+
+    pub fn is_auto(self, db: &dyn HirDatabase) -> bool {
+        db.trait_data(self.id).is_auto
+    }
+
+    pub fn is_unsafe(&self, db: &dyn HirDatabase) -> bool {
+        db.trait_data(self.id).is_unsafe
+    }
+
+    pub fn type_or_const_param_count(
+        &self,
+        db: &dyn HirDatabase,
+        count_required_only: bool,
+    ) -> usize {
+        db.generic_params(GenericDefId::from(self.id))
+            .type_or_consts
+            .iter()
+            .filter(|(_, ty)| match ty {
+                TypeOrConstParamData::TypeParamData(ty)
+                    if ty.provenance != TypeParamProvenance::TypeParamList =>
+                {
+                    false
+                }
+                _ => true,
+            })
+            .filter(|(_, ty)| !count_required_only || !ty.has_default())
+            .count()
+    }
+}
+
+impl HasVisibility for Trait {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        db.trait_data(self.id).visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct TypeAlias {
+    pub(crate) id: TypeAliasId,
+}
+
+impl TypeAlias {
+    pub fn has_non_default_type_params(self, db: &dyn HirDatabase) -> bool {
+        let subst = db.generic_defaults(self.id.into());
+        subst.iter().any(|ty| match ty.skip_binders().data(Interner) {
+            GenericArgData::Ty(x) => x.is_unknown(),
+            _ => false,
+        })
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
+    }
+
+    pub fn type_ref(self, db: &dyn HirDatabase) -> Option<TypeRef> {
+        db.type_alias_data(self.id).type_ref.as_deref().cloned()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::from_def(db, self.id)
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        db.type_alias_data(self.id).name.clone()
+    }
+}
+
+impl HasVisibility for TypeAlias {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        let function_data = db.type_alias_data(self.id);
+        let visibility = &function_data.visibility;
+        visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct BuiltinType {
+    pub(crate) inner: hir_def::builtin_type::BuiltinType,
+}
+
+impl BuiltinType {
+    pub fn str() -> BuiltinType {
+        BuiltinType { inner: hir_def::builtin_type::BuiltinType::Str }
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::new_for_crate(db.crate_graph().iter().next().unwrap(), TyBuilder::builtin(self.inner))
+    }
+
+    pub fn name(self) -> Name {
+        self.inner.as_name()
+    }
+
+    pub fn is_int(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Int(_))
+    }
+
+    pub fn is_uint(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Uint(_))
+    }
+
+    pub fn is_float(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Float(_))
+    }
+
+    pub fn is_char(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Char)
+    }
+
+    pub fn is_bool(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Bool)
+    }
+
+    pub fn is_str(&self) -> bool {
+        matches!(self.inner, hir_def::builtin_type::BuiltinType::Str)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum MacroKind {
+    /// `macro_rules!` or Macros 2.0 macro.
+    Declarative,
+    /// A built-in or custom derive.
+    Derive,
+    /// A built-in function-like macro.
+    BuiltIn,
+    /// A procedural attribute macro.
+    Attr,
+    /// A function-like procedural macro.
+    ProcMacro,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Macro {
+    pub(crate) id: MacroId,
+}
+
+impl Macro {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        Module { id: self.id.module(db.upcast()) }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        match self.id {
+            MacroId::Macro2Id(id) => db.macro2_data(id).name.clone(),
+            MacroId::MacroRulesId(id) => db.macro_rules_data(id).name.clone(),
+            MacroId::ProcMacroId(id) => db.proc_macro_data(id).name.clone(),
+        }
+    }
+
+    pub fn is_macro_export(self, db: &dyn HirDatabase) -> bool {
+        matches!(self.id, MacroId::MacroRulesId(id) if db.macro_rules_data(id).macro_export)
+    }
+
+    pub fn kind(&self, db: &dyn HirDatabase) -> MacroKind {
+        match self.id {
+            MacroId::Macro2Id(it) => match it.lookup(db.upcast()).expander {
+                MacroExpander::Declarative => MacroKind::Declarative,
+                MacroExpander::BuiltIn(_) | MacroExpander::BuiltInEager(_) => MacroKind::BuiltIn,
+                MacroExpander::BuiltInAttr(_) => MacroKind::Attr,
+                MacroExpander::BuiltInDerive(_) => MacroKind::Derive,
+            },
+            MacroId::MacroRulesId(it) => match it.lookup(db.upcast()).expander {
+                MacroExpander::Declarative => MacroKind::Declarative,
+                MacroExpander::BuiltIn(_) | MacroExpander::BuiltInEager(_) => MacroKind::BuiltIn,
+                MacroExpander::BuiltInAttr(_) => MacroKind::Attr,
+                MacroExpander::BuiltInDerive(_) => MacroKind::Derive,
+            },
+            MacroId::ProcMacroId(it) => match it.lookup(db.upcast()).kind {
+                ProcMacroKind::CustomDerive => MacroKind::Derive,
+                ProcMacroKind::FuncLike => MacroKind::ProcMacro,
+                ProcMacroKind::Attr => MacroKind::Attr,
+            },
+        }
+    }
+
+    pub fn is_fn_like(&self, db: &dyn HirDatabase) -> bool {
+        match self.kind(db) {
+            MacroKind::Declarative | MacroKind::BuiltIn | MacroKind::ProcMacro => true,
+            MacroKind::Attr | MacroKind::Derive => false,
+        }
+    }
+
+    pub fn is_builtin_derive(&self, db: &dyn HirDatabase) -> bool {
+        match self.id {
+            MacroId::Macro2Id(it) => {
+                matches!(it.lookup(db.upcast()).expander, MacroExpander::BuiltInDerive(_))
+            }
+            MacroId::MacroRulesId(it) => {
+                matches!(it.lookup(db.upcast()).expander, MacroExpander::BuiltInDerive(_))
+            }
+            MacroId::ProcMacroId(_) => false,
+        }
+    }
+
+    pub fn is_attr(&self, db: &dyn HirDatabase) -> bool {
+        matches!(self.kind(db), MacroKind::Attr)
+    }
+
+    pub fn is_derive(&self, db: &dyn HirDatabase) -> bool {
+        matches!(self.kind(db), MacroKind::Derive)
+    }
+}
+
+impl HasVisibility for Macro {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        match self.id {
+            MacroId::Macro2Id(id) => {
+                let data = db.macro2_data(id);
+                let visibility = &data.visibility;
+                visibility.resolve(db.upcast(), &self.id.resolver(db.upcast()))
+            }
+            MacroId::MacroRulesId(_) => Visibility::Public,
+            MacroId::ProcMacroId(_) => Visibility::Public,
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+pub enum ItemInNs {
+    Types(ModuleDef),
+    Values(ModuleDef),
+    Macros(Macro),
+}
+
+impl From<Macro> for ItemInNs {
+    fn from(it: Macro) -> Self {
+        Self::Macros(it)
+    }
+}
+
+impl From<ModuleDef> for ItemInNs {
+    fn from(module_def: ModuleDef) -> Self {
+        match module_def {
+            ModuleDef::Static(_) | ModuleDef::Const(_) | ModuleDef::Function(_) => {
+                ItemInNs::Values(module_def)
+            }
+            _ => ItemInNs::Types(module_def),
+        }
+    }
+}
+
+impl ItemInNs {
+    pub fn as_module_def(self) -> Option<ModuleDef> {
+        match self {
+            ItemInNs::Types(id) | ItemInNs::Values(id) => Some(id),
+            ItemInNs::Macros(_) => None,
+        }
+    }
+
+    /// Returns the crate defining this item (or `None` if `self` is built-in).
+    pub fn krate(&self, db: &dyn HirDatabase) -> Option<Crate> {
+        match self {
+            ItemInNs::Types(did) | ItemInNs::Values(did) => did.module(db).map(|m| m.krate()),
+            ItemInNs::Macros(id) => Some(id.module(db).krate()),
+        }
+    }
+
+    pub fn attrs(&self, db: &dyn HirDatabase) -> Option<AttrsWithOwner> {
+        match self {
+            ItemInNs::Types(it) | ItemInNs::Values(it) => it.attrs(db),
+            ItemInNs::Macros(it) => Some(it.attrs(db)),
+        }
+    }
+}
+
+/// Invariant: `inner.as_assoc_item(db).is_some()`
+/// We do not actively enforce this invariant.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum AssocItem {
+    Function(Function),
+    Const(Const),
+    TypeAlias(TypeAlias),
+}
+#[derive(Debug)]
+pub enum AssocItemContainer {
+    Trait(Trait),
+    Impl(Impl),
+}
+pub trait AsAssocItem {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem>;
+}
+
+impl AsAssocItem for Function {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::Function, self.id)
+    }
+}
+impl AsAssocItem for Const {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::Const, self.id)
+    }
+}
+impl AsAssocItem for TypeAlias {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::TypeAlias, self.id)
+    }
+}
+impl AsAssocItem for ModuleDef {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem> {
+        match self {
+            ModuleDef::Function(it) => it.as_assoc_item(db),
+            ModuleDef::Const(it) => it.as_assoc_item(db),
+            ModuleDef::TypeAlias(it) => it.as_assoc_item(db),
+            _ => None,
+        }
+    }
+}
+fn as_assoc_item<ID, DEF, CTOR, AST>(db: &dyn HirDatabase, ctor: CTOR, id: ID) -> Option<AssocItem>
+where
+    ID: Lookup<Data = AssocItemLoc<AST>>,
+    DEF: From<ID>,
+    CTOR: FnOnce(DEF) -> AssocItem,
+    AST: ItemTreeNode,
+{
+    match id.lookup(db.upcast()).container {
+        ItemContainerId::TraitId(_) | ItemContainerId::ImplId(_) => Some(ctor(DEF::from(id))),
+        ItemContainerId::ModuleId(_) | ItemContainerId::ExternBlockId(_) => None,
+    }
+}
+
+impl AssocItem {
+    pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
+        match self {
+            AssocItem::Function(it) => Some(it.name(db)),
+            AssocItem::Const(it) => it.name(db),
+            AssocItem::TypeAlias(it) => Some(it.name(db)),
+        }
+    }
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        match self {
+            AssocItem::Function(f) => f.module(db),
+            AssocItem::Const(c) => c.module(db),
+            AssocItem::TypeAlias(t) => t.module(db),
+        }
+    }
+    pub fn container(self, db: &dyn HirDatabase) -> AssocItemContainer {
+        let container = match self {
+            AssocItem::Function(it) => it.id.lookup(db.upcast()).container,
+            AssocItem::Const(it) => it.id.lookup(db.upcast()).container,
+            AssocItem::TypeAlias(it) => it.id.lookup(db.upcast()).container,
+        };
+        match container {
+            ItemContainerId::TraitId(id) => AssocItemContainer::Trait(id.into()),
+            ItemContainerId::ImplId(id) => AssocItemContainer::Impl(id.into()),
+            ItemContainerId::ModuleId(_) | ItemContainerId::ExternBlockId(_) => {
+                panic!("invalid AssocItem")
+            }
+        }
+    }
+
+    pub fn containing_trait(self, db: &dyn HirDatabase) -> Option<Trait> {
+        match self.container(db) {
+            AssocItemContainer::Trait(t) => Some(t),
+            _ => None,
+        }
+    }
+
+    pub fn containing_trait_impl(self, db: &dyn HirDatabase) -> Option<Trait> {
+        match self.container(db) {
+            AssocItemContainer::Impl(i) => i.trait_(db),
+            _ => None,
+        }
+    }
+
+    pub fn containing_trait_or_trait_impl(self, db: &dyn HirDatabase) -> Option<Trait> {
+        match self.container(db) {
+            AssocItemContainer::Trait(t) => Some(t),
+            AssocItemContainer::Impl(i) => i.trait_(db),
+        }
+    }
+}
+
+impl HasVisibility for AssocItem {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
+        match self {
+            AssocItem::Function(f) => f.visibility(db),
+            AssocItem::Const(c) => c.visibility(db),
+            AssocItem::TypeAlias(t) => t.visibility(db),
+        }
+    }
+}
+
+impl From<AssocItem> for ModuleDef {
+    fn from(assoc: AssocItem) -> Self {
+        match assoc {
+            AssocItem::Function(it) => ModuleDef::Function(it),
+            AssocItem::Const(it) => ModuleDef::Const(it),
+            AssocItem::TypeAlias(it) => ModuleDef::TypeAlias(it),
+        }
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
+pub enum GenericDef {
+    Function(Function),
+    Adt(Adt),
+    Trait(Trait),
+    TypeAlias(TypeAlias),
+    Impl(Impl),
+    // enum variants cannot have generics themselves, but their parent enums
+    // can, and this makes some code easier to write
+    Variant(Variant),
+    // consts can have type parameters from their parents (i.e. associated consts of traits)
+    Const(Const),
+}
+impl_from!(
+    Function,
+    Adt(Struct, Enum, Union),
+    Trait,
+    TypeAlias,
+    Impl,
+    Variant,
+    Const
+    for GenericDef
+);
+
+impl GenericDef {
+    pub fn params(self, db: &dyn HirDatabase) -> Vec<GenericParam> {
+        let generics = db.generic_params(self.into());
+        let ty_params = generics.type_or_consts.iter().map(|(local_id, _)| {
+            let toc = TypeOrConstParam { id: TypeOrConstParamId { parent: self.into(), local_id } };
+            match toc.split(db) {
+                Either::Left(x) => GenericParam::ConstParam(x),
+                Either::Right(x) => GenericParam::TypeParam(x),
+            }
+        });
+        let lt_params = generics
+            .lifetimes
+            .iter()
+            .map(|(local_id, _)| LifetimeParam {
+                id: LifetimeParamId { parent: self.into(), local_id },
+            })
+            .map(GenericParam::LifetimeParam);
+        lt_params.chain(ty_params).collect()
+    }
+
+    pub fn type_params(self, db: &dyn HirDatabase) -> Vec<TypeOrConstParam> {
+        let generics = db.generic_params(self.into());
+        generics
+            .type_or_consts
+            .iter()
+            .map(|(local_id, _)| TypeOrConstParam {
+                id: TypeOrConstParamId { parent: self.into(), local_id },
+            })
+            .collect()
+    }
+}
+
+/// A single local definition.
+///
+/// If the definition of this is part of a "MultiLocal", that is a local that has multiple declarations due to or-patterns
+/// then this only references a single one of those.
+/// To retrieve the other locals you should use [`Local::associated_locals`]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct Local {
+    pub(crate) parent: DefWithBodyId,
+    pub(crate) pat_id: PatId,
+}
+
+impl Local {
+    pub fn is_param(self, db: &dyn HirDatabase) -> bool {
+        let src = self.source(db);
+        match src.value {
+            Either::Left(pat) => pat
+                .syntax()
+                .ancestors()
+                .map(|it| it.kind())
+                .take_while(|&kind| ast::Pat::can_cast(kind) || ast::Param::can_cast(kind))
+                .any(ast::Param::can_cast),
+            Either::Right(_) => true,
+        }
+    }
+
+    pub fn as_self_param(self, db: &dyn HirDatabase) -> Option<SelfParam> {
+        match self.parent {
+            DefWithBodyId::FunctionId(func) if self.is_self(db) => Some(SelfParam { func }),
+            _ => None,
+        }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let body = db.body(self.parent);
+        match &body[self.pat_id] {
+            Pat::Bind { name, .. } => name.clone(),
+            _ => {
+                stdx::never!("hir::Local is missing a name!");
+                Name::missing()
+            }
+        }
+    }
+
+    pub fn is_self(self, db: &dyn HirDatabase) -> bool {
+        self.name(db) == name![self]
+    }
+
+    pub fn is_mut(self, db: &dyn HirDatabase) -> bool {
+        let body = db.body(self.parent);
+        matches!(&body[self.pat_id], Pat::Bind { mode: BindingAnnotation::Mutable, .. })
+    }
+
+    pub fn is_ref(self, db: &dyn HirDatabase) -> bool {
+        let body = db.body(self.parent);
+        matches!(
+            &body[self.pat_id],
+            Pat::Bind { mode: BindingAnnotation::Ref | BindingAnnotation::RefMut, .. }
+        )
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> DefWithBody {
+        self.parent.into()
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.parent(db).module(db)
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let def = self.parent;
+        let infer = db.infer(def);
+        let ty = infer[self.pat_id].clone();
+        Type::new(db, def, ty)
+    }
+
+    pub fn associated_locals(self, db: &dyn HirDatabase) -> Box<[Local]> {
+        let body = db.body(self.parent);
+        body.ident_patterns_for(&self.pat_id)
+            .iter()
+            .map(|&pat_id| Local { parent: self.parent, pat_id })
+            .collect()
+    }
+
+    /// If this local is part of a multi-local, retrieve the representative local.
+    /// That is the local that references are being resolved to.
+    pub fn representative(self, db: &dyn HirDatabase) -> Local {
+        let body = db.body(self.parent);
+        Local { pat_id: body.pattern_representative(self.pat_id), ..self }
+    }
+
+    pub fn source(self, db: &dyn HirDatabase) -> InFile<Either<ast::IdentPat, ast::SelfParam>> {
+        let (_body, source_map) = db.body_with_source_map(self.parent);
+        let src = source_map.pat_syntax(self.pat_id).unwrap(); // Hmm...
+        let root = src.file_syntax(db.upcast());
+        src.map(|ast| match ast {
+            // Suspicious unwrap
+            Either::Left(it) => Either::Left(it.cast().unwrap().to_node(&root)),
+            Either::Right(it) => Either::Right(it.to_node(&root)),
+        })
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct DeriveHelper {
+    pub(crate) derive: MacroId,
+    pub(crate) idx: usize,
+}
+
+impl DeriveHelper {
+    pub fn derive(&self) -> Macro {
+        Macro { id: self.derive.into() }
+    }
+
+    pub fn name(&self, db: &dyn HirDatabase) -> Name {
+        match self.derive {
+            MacroId::Macro2Id(_) => None,
+            MacroId::MacroRulesId(_) => None,
+            MacroId::ProcMacroId(proc_macro) => db
+                .proc_macro_data(proc_macro)
+                .helpers
+                .as_ref()
+                .and_then(|it| it.get(self.idx))
+                .cloned(),
+        }
+        .unwrap_or_else(|| Name::missing())
+    }
+}
+
+// FIXME: Wrong name? This is could also be a registered attribute
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct BuiltinAttr {
+    krate: Option<CrateId>,
+    idx: usize,
+}
+
+impl BuiltinAttr {
+    // FIXME: consider crates\hir_def\src\nameres\attr_resolution.rs?
+    pub(crate) fn by_name(db: &dyn HirDatabase, krate: Crate, name: &str) -> Option<Self> {
+        if let builtin @ Some(_) = Self::builtin(name) {
+            return builtin;
+        }
+        let idx = db.crate_def_map(krate.id).registered_attrs().iter().position(|it| it == name)?;
+        Some(BuiltinAttr { krate: Some(krate.id), idx })
+    }
+
+    fn builtin(name: &str) -> Option<Self> {
+        hir_def::builtin_attr::INERT_ATTRIBUTES
+            .iter()
+            .position(|tool| tool.name == name)
+            .map(|idx| BuiltinAttr { krate: None, idx })
+    }
+
+    pub fn name(&self, db: &dyn HirDatabase) -> SmolStr {
+        // FIXME: Return a `Name` here
+        match self.krate {
+            Some(krate) => db.crate_def_map(krate).registered_attrs()[self.idx].clone(),
+            None => SmolStr::new(hir_def::builtin_attr::INERT_ATTRIBUTES[self.idx].name),
+        }
+    }
+
+    pub fn template(&self, _: &dyn HirDatabase) -> Option<AttributeTemplate> {
+        match self.krate {
+            Some(_) => None,
+            None => Some(hir_def::builtin_attr::INERT_ATTRIBUTES[self.idx].template),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct ToolModule {
+    krate: Option<CrateId>,
+    idx: usize,
+}
+
+impl ToolModule {
+    // FIXME: consider crates\hir_def\src\nameres\attr_resolution.rs?
+    pub(crate) fn by_name(db: &dyn HirDatabase, krate: Crate, name: &str) -> Option<Self> {
+        if let builtin @ Some(_) = Self::builtin(name) {
+            return builtin;
+        }
+        let idx = db.crate_def_map(krate.id).registered_tools().iter().position(|it| it == name)?;
+        Some(ToolModule { krate: Some(krate.id), idx })
+    }
+
+    fn builtin(name: &str) -> Option<Self> {
+        hir_def::builtin_attr::TOOL_MODULES
+            .iter()
+            .position(|&tool| tool == name)
+            .map(|idx| ToolModule { krate: None, idx })
+    }
+
+    pub fn name(&self, db: &dyn HirDatabase) -> SmolStr {
+        // FIXME: Return a `Name` here
+        match self.krate {
+            Some(krate) => db.crate_def_map(krate).registered_tools()[self.idx].clone(),
+            None => SmolStr::new(hir_def::builtin_attr::TOOL_MODULES[self.idx]),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct Label {
+    pub(crate) parent: DefWithBodyId,
+    pub(crate) label_id: LabelId,
+}
+
+impl Label {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.parent(db).module(db)
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> DefWithBody {
+        self.parent.into()
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let body = db.body(self.parent);
+        body[self.label_id].name.clone()
+    }
+
+    pub fn source(self, db: &dyn HirDatabase) -> InFile<ast::Label> {
+        let (_body, source_map) = db.body_with_source_map(self.parent);
+        let src = source_map.label_syntax(self.label_id);
+        let root = src.file_syntax(db.upcast());
+        src.map(|ast| ast.to_node(&root))
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum GenericParam {
+    TypeParam(TypeParam),
+    ConstParam(ConstParam),
+    LifetimeParam(LifetimeParam),
+}
+impl_from!(TypeParam, ConstParam, LifetimeParam for GenericParam);
+
+impl GenericParam {
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        match self {
+            GenericParam::TypeParam(it) => it.module(db),
+            GenericParam::ConstParam(it) => it.module(db),
+            GenericParam::LifetimeParam(it) => it.module(db),
+        }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        match self {
+            GenericParam::TypeParam(it) => it.name(db),
+            GenericParam::ConstParam(it) => it.name(db),
+            GenericParam::LifetimeParam(it) => it.name(db),
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct TypeParam {
+    pub(crate) id: TypeParamId,
+}
+
+impl TypeParam {
+    pub fn merge(self) -> TypeOrConstParam {
+        TypeOrConstParam { id: self.id.into() }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        self.merge().name(db)
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent().module(db.upcast()).into()
+    }
+
+    /// Is this type parameter implicitly introduced (eg. `Self` in a trait or an `impl Trait`
+    /// argument)?
+    pub fn is_implicit(self, db: &dyn HirDatabase) -> bool {
+        let params = db.generic_params(self.id.parent());
+        let data = &params.type_or_consts[self.id.local_id()];
+        match data.type_param().unwrap().provenance {
+            hir_def::generics::TypeParamProvenance::TypeParamList => false,
+            hir_def::generics::TypeParamProvenance::TraitSelf
+            | hir_def::generics::TypeParamProvenance::ArgumentImplTrait => true,
+        }
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let resolver = self.id.parent().resolver(db.upcast());
+        let ty =
+            TyKind::Placeholder(hir_ty::to_placeholder_idx(db, self.id.into())).intern(Interner);
+        Type::new_with_resolver_inner(db, &resolver, ty)
+    }
+
+    /// FIXME: this only lists trait bounds from the item defining the type
+    /// parameter, not additional bounds that might be added e.g. by a method if
+    /// the parameter comes from an impl!
+    pub fn trait_bounds(self, db: &dyn HirDatabase) -> Vec<Trait> {
+        db.generic_predicates_for_param(self.id.parent(), self.id.into(), None)
+            .iter()
+            .filter_map(|pred| match &pred.skip_binders().skip_binders() {
+                hir_ty::WhereClause::Implemented(trait_ref) => {
+                    Some(Trait::from(trait_ref.hir_trait_id()))
+                }
+                _ => None,
+            })
+            .collect()
+    }
+
+    pub fn default(self, db: &dyn HirDatabase) -> Option<Type> {
+        let params = db.generic_defaults(self.id.parent());
+        let local_idx = hir_ty::param_idx(db, self.id.into())?;
+        let resolver = self.id.parent().resolver(db.upcast());
+        let ty = params.get(local_idx)?.clone();
+        let subst = TyBuilder::placeholder_subst(db, self.id.parent());
+        let ty = ty.substitute(Interner, &subst_prefix(&subst, local_idx));
+        match ty.data(Interner) {
+            GenericArgData::Ty(x) => Some(Type::new_with_resolver_inner(db, &resolver, x.clone())),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct LifetimeParam {
+    pub(crate) id: LifetimeParamId,
+}
+
+impl LifetimeParam {
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let params = db.generic_params(self.id.parent);
+        params.lifetimes[self.id.local_id].name.clone()
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent.module(db.upcast()).into()
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
+        self.id.parent.into()
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct ConstParam {
+    pub(crate) id: ConstParamId,
+}
+
+impl ConstParam {
+    pub fn merge(self) -> TypeOrConstParam {
+        TypeOrConstParam { id: self.id.into() }
+    }
+
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let params = db.generic_params(self.id.parent());
+        match params.type_or_consts[self.id.local_id()].name() {
+            Some(x) => x.clone(),
+            None => {
+                never!();
+                Name::missing()
+            }
+        }
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent().module(db.upcast()).into()
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
+        self.id.parent().into()
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        Type::new(db, self.id.parent(), db.const_param_ty(self.id))
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct TypeOrConstParam {
+    pub(crate) id: TypeOrConstParamId,
+}
+
+impl TypeOrConstParam {
+    pub fn name(self, db: &dyn HirDatabase) -> Name {
+        let params = db.generic_params(self.id.parent);
+        match params.type_or_consts[self.id.local_id].name() {
+            Some(n) => n.clone(),
+            _ => Name::missing(),
+        }
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent.module(db.upcast()).into()
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
+        self.id.parent.into()
+    }
+
+    pub fn split(self, db: &dyn HirDatabase) -> Either<ConstParam, TypeParam> {
+        let params = db.generic_params(self.id.parent);
+        match &params.type_or_consts[self.id.local_id] {
+            hir_def::generics::TypeOrConstParamData::TypeParamData(_) => {
+                Either::Right(TypeParam { id: TypeParamId::from_unchecked(self.id) })
+            }
+            hir_def::generics::TypeOrConstParamData::ConstParamData(_) => {
+                Either::Left(ConstParam { id: ConstParamId::from_unchecked(self.id) })
+            }
+        }
+    }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        match self.split(db) {
+            Either::Left(x) => x.ty(db),
+            Either::Right(x) => x.ty(db),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Impl {
+    pub(crate) id: ImplId,
+}
+
+impl Impl {
+    pub fn all_in_crate(db: &dyn HirDatabase, krate: Crate) -> Vec<Impl> {
+        let inherent = db.inherent_impls_in_crate(krate.id);
+        let trait_ = db.trait_impls_in_crate(krate.id);
+
+        inherent.all_impls().chain(trait_.all_impls()).map(Self::from).collect()
+    }
+
+    pub fn all_for_type(db: &dyn HirDatabase, Type { ty, env }: Type) -> Vec<Impl> {
+        let def_crates = match method_resolution::def_crates(db, &ty, env.krate) {
+            Some(def_crates) => def_crates,
+            None => return Vec::new(),
+        };
+
+        let filter = |impl_def: &Impl| {
+            let self_ty = impl_def.self_ty(db);
+            let rref = self_ty.remove_ref();
+            ty.equals_ctor(rref.as_ref().map_or(&self_ty.ty, |it| &it.ty))
+        };
+
+        let fp = TyFingerprint::for_inherent_impl(&ty);
+        let fp = match fp {
+            Some(fp) => fp,
+            None => return Vec::new(),
+        };
+
+        let mut all = Vec::new();
+        def_crates.iter().for_each(|&id| {
+            all.extend(
+                db.inherent_impls_in_crate(id)
+                    .for_self_ty(&ty)
+                    .iter()
+                    .cloned()
+                    .map(Self::from)
+                    .filter(filter),
+            )
+        });
+        for id in def_crates
+            .iter()
+            .flat_map(|&id| Crate { id }.transitive_reverse_dependencies(db))
+            .map(|Crate { id }| id)
+            .chain(def_crates.iter().copied())
+            .unique()
+        {
+            all.extend(
+                db.trait_impls_in_crate(id)
+                    .for_self_ty_without_blanket_impls(fp)
+                    .map(Self::from)
+                    .filter(filter),
+            );
+        }
+        all
+    }
+
+    pub fn all_for_trait(db: &dyn HirDatabase, trait_: Trait) -> Vec<Impl> {
+        let krate = trait_.module(db).krate();
+        let mut all = Vec::new();
+        for Crate { id } in krate.transitive_reverse_dependencies(db).into_iter() {
+            let impls = db.trait_impls_in_crate(id);
+            all.extend(impls.for_trait(trait_.id).map(Self::from))
+        }
+        all
+    }
+
+    // FIXME: the return type is wrong. This should be a hir version of
+    // `TraitRef` (to account for parameters and qualifiers)
+    pub fn trait_(self, db: &dyn HirDatabase) -> Option<Trait> {
+        let trait_ref = db.impl_trait(self.id)?.skip_binders().clone();
+        let id = hir_ty::from_chalk_trait_id(trait_ref.trait_id);
+        Some(Trait { id })
+    }
+
+    pub fn self_ty(self, db: &dyn HirDatabase) -> Type {
+        let resolver = self.id.resolver(db.upcast());
+        let substs = TyBuilder::placeholder_subst(db, self.id);
+        let ty = db.impl_self_ty(self.id).substitute(Interner, &substs);
+        Type::new_with_resolver_inner(db, &resolver, ty)
+    }
+
+    pub fn items(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
+        db.impl_data(self.id).items.iter().map(|it| (*it).into()).collect()
+    }
+
+    pub fn is_negative(self, db: &dyn HirDatabase) -> bool {
+        db.impl_data(self.id).is_negative
+    }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.lookup(db.upcast()).container.into()
+    }
+
+    pub fn is_builtin_derive(self, db: &dyn HirDatabase) -> Option<InFile<ast::Attr>> {
+        let src = self.source(db)?;
+        src.file_id.is_builtin_derive(db.upcast())
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Type {
+    env: Arc<TraitEnvironment>,
+    ty: Ty,
+}
+
+impl Type {
+    pub(crate) fn new_with_resolver(db: &dyn HirDatabase, resolver: &Resolver, ty: Ty) -> Type {
+        Type::new_with_resolver_inner(db, resolver, ty)
+    }
+
+    pub(crate) fn new_with_resolver_inner(
+        db: &dyn HirDatabase,
+        resolver: &Resolver,
+        ty: Ty,
+    ) -> Type {
+        let environment = resolver.generic_def().map_or_else(
+            || Arc::new(TraitEnvironment::empty(resolver.krate())),
+            |d| db.trait_environment(d),
+        );
+        Type { env: environment, ty }
+    }
+
+    pub(crate) fn new_for_crate(krate: CrateId, ty: Ty) -> Type {
+        Type { env: Arc::new(TraitEnvironment::empty(krate)), ty }
+    }
+
+    pub fn reference(inner: &Type, m: Mutability) -> Type {
+        inner.derived(
+            TyKind::Ref(
+                if m.is_mut() { hir_ty::Mutability::Mut } else { hir_ty::Mutability::Not },
+                hir_ty::static_lifetime(),
+                inner.ty.clone(),
+            )
+            .intern(Interner),
+        )
+    }
+
+    fn new(db: &dyn HirDatabase, lexical_env: impl HasResolver, ty: Ty) -> Type {
+        let resolver = lexical_env.resolver(db.upcast());
+        let environment = resolver.generic_def().map_or_else(
+            || Arc::new(TraitEnvironment::empty(resolver.krate())),
+            |d| db.trait_environment(d),
+        );
+        Type { env: environment, ty }
+    }
+
+    fn from_def(db: &dyn HirDatabase, def: impl HasResolver + Into<TyDefId>) -> Type {
+        let ty = TyBuilder::def_ty(db, def.into()).fill_with_unknown().build();
+        Type::new(db, def, ty)
+    }
+
+    pub fn new_slice(ty: Type) -> Type {
+        Type { env: ty.env, ty: TyBuilder::slice(ty.ty) }
+    }
+
+    pub fn is_unit(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Tuple(0, ..))
+    }
+
+    pub fn is_bool(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Scalar(Scalar::Bool))
+    }
+
+    pub fn is_never(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Never)
+    }
+
+    pub fn is_mutable_reference(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Ref(hir_ty::Mutability::Mut, ..))
+    }
+
+    pub fn is_reference(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Ref(..))
+    }
+
+    pub fn as_reference(&self) -> Option<(Type, Mutability)> {
+        let (ty, _lt, m) = self.ty.as_reference()?;
+        let m = Mutability::from_mutable(matches!(m, hir_ty::Mutability::Mut));
+        Some((self.derived(ty.clone()), m))
+    }
+
+    pub fn is_slice(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Slice(..))
+    }
+
+    pub fn is_usize(&self) -> bool {
+        matches!(self.ty.kind(Interner), TyKind::Scalar(Scalar::Uint(UintTy::Usize)))
+    }
+
+    pub fn remove_ref(&self) -> Option<Type> {
+        match &self.ty.kind(Interner) {
+            TyKind::Ref(.., ty) => Some(self.derived(ty.clone())),
+            _ => None,
+        }
+    }
+
+    pub fn strip_references(&self) -> Type {
+        self.derived(self.ty.strip_references().clone())
+    }
+
+    pub fn strip_reference(&self) -> Type {
+        self.derived(self.ty.strip_reference().clone())
+    }
+
+    pub fn is_unknown(&self) -> bool {
+        self.ty.is_unknown()
+    }
+
+    /// Checks that particular type `ty` implements `std::future::Future`.
+    /// This function is used in `.await` syntax completion.
+    pub fn impls_future(&self, db: &dyn HirDatabase) -> bool {
+        let std_future_trait = db
+            .lang_item(self.env.krate, SmolStr::new_inline("future_trait"))
+            .and_then(|it| it.as_trait());
+        let std_future_trait = match std_future_trait {
+            Some(it) => it,
+            None => return false,
+        };
+
+        let canonical_ty =
+            Canonical { value: self.ty.clone(), binders: CanonicalVarKinds::empty(Interner) };
+        method_resolution::implements_trait(&canonical_ty, db, self.env.clone(), std_future_trait)
+    }
+
+    /// Checks that particular type `ty` implements `std::ops::FnOnce`.
+    ///
+    /// This function can be used to check if a particular type is callable, since FnOnce is a
+    /// supertrait of Fn and FnMut, so all callable types implements at least FnOnce.
+    pub fn impls_fnonce(&self, db: &dyn HirDatabase) -> bool {
+        let fnonce_trait = match FnTrait::FnOnce.get_id(db, self.env.krate) {
+            Some(it) => it,
+            None => return false,
+        };
+
+        let canonical_ty =
+            Canonical { value: self.ty.clone(), binders: CanonicalVarKinds::empty(Interner) };
+        method_resolution::implements_trait_unique(
+            &canonical_ty,
+            db,
+            self.env.clone(),
+            fnonce_trait,
+        )
+    }
+
+    pub fn impls_trait(&self, db: &dyn HirDatabase, trait_: Trait, args: &[Type]) -> bool {
+        let mut it = args.iter().map(|t| t.ty.clone());
+        let trait_ref = TyBuilder::trait_ref(db, trait_.id)
+            .push(self.ty.clone())
+            .fill(|x| {
+                let r = it.next().unwrap();
+                match x {
+                    ParamKind::Type => GenericArgData::Ty(r).intern(Interner),
+                    ParamKind::Const(ty) => {
+                        // FIXME: this code is not covered in tests.
+                        unknown_const_as_generic(ty.clone())
+                    }
+                }
+            })
+            .build();
+
+        let goal = Canonical {
+            value: hir_ty::InEnvironment::new(&self.env.env, trait_ref.cast(Interner)),
+            binders: CanonicalVarKinds::empty(Interner),
+        };
+
+        db.trait_solve(self.env.krate, goal).is_some()
+    }
+
+    pub fn normalize_trait_assoc_type(
+        &self,
+        db: &dyn HirDatabase,
+        args: &[Type],
+        alias: TypeAlias,
+    ) -> Option<Type> {
+        let mut args = args.iter();
+        let projection = TyBuilder::assoc_type_projection(db, alias.id)
+            .push(self.ty.clone())
+            .fill(|x| {
+                // FIXME: this code is not covered in tests.
+                match x {
+                    ParamKind::Type => {
+                        GenericArgData::Ty(args.next().unwrap().ty.clone()).intern(Interner)
+                    }
+                    ParamKind::Const(ty) => unknown_const_as_generic(ty.clone()),
+                }
+            })
+            .build();
+        let goal = hir_ty::make_canonical(
+            InEnvironment::new(
+                &self.env.env,
+                AliasEq {
+                    alias: AliasTy::Projection(projection),
+                    ty: TyKind::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0))
+                        .intern(Interner),
+                }
+                .cast(Interner),
+            ),
+            [TyVariableKind::General].into_iter(),
+        );
+
+        match db.trait_solve(self.env.krate, goal)? {
+            Solution::Unique(s) => s
+                .value
+                .subst
+                .as_slice(Interner)
+                .first()
+                .map(|ty| self.derived(ty.assert_ty_ref(Interner).clone())),
+            Solution::Ambig(_) => None,
+        }
+    }
+
+    pub fn is_copy(&self, db: &dyn HirDatabase) -> bool {
+        let lang_item = db.lang_item(self.env.krate, SmolStr::new_inline("copy"));
+        let copy_trait = match lang_item {
+            Some(LangItemTarget::TraitId(it)) => it,
+            _ => return false,
+        };
+        self.impls_trait(db, copy_trait.into(), &[])
+    }
+
+    pub fn as_callable(&self, db: &dyn HirDatabase) -> Option<Callable> {
+        let callee = match self.ty.kind(Interner) {
+            TyKind::Closure(id, _) => Callee::Closure(*id),
+            TyKind::Function(_) => Callee::FnPtr,
+            _ => Callee::Def(self.ty.callable_def(db)?),
+        };
+
+        let sig = self.ty.callable_sig(db)?;
+        Some(Callable { ty: self.clone(), sig, callee, is_bound_method: false })
+    }
+
+    pub fn is_closure(&self) -> bool {
+        matches!(&self.ty.kind(Interner), TyKind::Closure { .. })
+    }
+
+    pub fn is_fn(&self) -> bool {
+        matches!(&self.ty.kind(Interner), TyKind::FnDef(..) | TyKind::Function { .. })
+    }
+
+    pub fn is_array(&self) -> bool {
+        matches!(&self.ty.kind(Interner), TyKind::Array(..))
+    }
+
+    pub fn is_packed(&self, db: &dyn HirDatabase) -> bool {
+        let adt_id = match *self.ty.kind(Interner) {
+            TyKind::Adt(hir_ty::AdtId(adt_id), ..) => adt_id,
+            _ => return false,
+        };
+
+        let adt = adt_id.into();
+        match adt {
+            Adt::Struct(s) => matches!(s.repr(db), Some(ReprKind::Packed)),
+            _ => false,
+        }
+    }
+
+    pub fn is_raw_ptr(&self) -> bool {
+        matches!(&self.ty.kind(Interner), TyKind::Raw(..))
+    }
+
+    pub fn contains_unknown(&self) -> bool {
+        return go(&self.ty);
+
+        fn go(ty: &Ty) -> bool {
+            match ty.kind(Interner) {
+                TyKind::Error => true,
+
+                TyKind::Adt(_, substs)
+                | TyKind::AssociatedType(_, substs)
+                | TyKind::Tuple(_, substs)
+                | TyKind::OpaqueType(_, substs)
+                | TyKind::FnDef(_, substs)
+                | TyKind::Closure(_, substs) => {
+                    substs.iter(Interner).filter_map(|a| a.ty(Interner)).any(go)
+                }
+
+                TyKind::Array(_ty, len) if len.is_unknown() => true,
+                TyKind::Array(ty, _)
+                | TyKind::Slice(ty)
+                | TyKind::Raw(_, ty)
+                | TyKind::Ref(_, _, ty) => go(ty),
+
+                TyKind::Scalar(_)
+                | TyKind::Str
+                | TyKind::Never
+                | TyKind::Placeholder(_)
+                | TyKind::BoundVar(_)
+                | TyKind::InferenceVar(_, _)
+                | TyKind::Dyn(_)
+                | TyKind::Function(_)
+                | TyKind::Alias(_)
+                | TyKind::Foreign(_)
+                | TyKind::Generator(..)
+                | TyKind::GeneratorWitness(..) => false,
+            }
+        }
+    }
+
+    pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
+        let (variant_id, substs) = match self.ty.kind(Interner) {
+            TyKind::Adt(hir_ty::AdtId(AdtId::StructId(s)), substs) => ((*s).into(), substs),
+            TyKind::Adt(hir_ty::AdtId(AdtId::UnionId(u)), substs) => ((*u).into(), substs),
+            _ => return Vec::new(),
+        };
+
+        db.field_types(variant_id)
+            .iter()
+            .map(|(local_id, ty)| {
+                let def = Field { parent: variant_id.into(), id: local_id };
+                let ty = ty.clone().substitute(Interner, substs);
+                (def, self.derived(ty))
+            })
+            .collect()
+    }
+
+    pub fn tuple_fields(&self, _db: &dyn HirDatabase) -> Vec<Type> {
+        if let TyKind::Tuple(_, substs) = &self.ty.kind(Interner) {
+            substs
+                .iter(Interner)
+                .map(|ty| self.derived(ty.assert_ty_ref(Interner).clone()))
+                .collect()
+        } else {
+            Vec::new()
+        }
+    }
+
+    pub fn autoderef<'a>(&'a self, db: &'a dyn HirDatabase) -> impl Iterator<Item = Type> + 'a {
+        self.autoderef_(db).map(move |ty| self.derived(ty))
+    }
+
+    fn autoderef_<'a>(&'a self, db: &'a dyn HirDatabase) -> impl Iterator<Item = Ty> + 'a {
+        // There should be no inference vars in types passed here
+        let canonical = hir_ty::replace_errors_with_variables(&self.ty);
+        let environment = self.env.clone();
+        autoderef(db, environment, canonical).map(|canonical| canonical.value)
+    }
+
+    // This would be nicer if it just returned an iterator, but that runs into
+    // lifetime problems, because we need to borrow temp `CrateImplDefs`.
+    pub fn iterate_assoc_items<T>(
+        &self,
+        db: &dyn HirDatabase,
+        krate: Crate,
+        mut callback: impl FnMut(AssocItem) -> Option<T>,
+    ) -> Option<T> {
+        let mut slot = None;
+        self.iterate_assoc_items_dyn(db, krate, &mut |assoc_item_id| {
+            slot = callback(assoc_item_id.into());
+            slot.is_some()
+        });
+        slot
+    }
+
+    fn iterate_assoc_items_dyn(
+        &self,
+        db: &dyn HirDatabase,
+        krate: Crate,
+        callback: &mut dyn FnMut(AssocItemId) -> bool,
+    ) {
+        let def_crates = match method_resolution::def_crates(db, &self.ty, krate.id) {
+            Some(it) => it,
+            None => return,
+        };
+        for krate in def_crates {
+            let impls = db.inherent_impls_in_crate(krate);
+
+            for impl_def in impls.for_self_ty(&self.ty) {
+                for &item in db.impl_data(*impl_def).items.iter() {
+                    if callback(item) {
+                        return;
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn type_arguments(&self) -> impl Iterator<Item = Type> + '_ {
+        self.ty
+            .strip_references()
+            .as_adt()
+            .into_iter()
+            .flat_map(|(_, substs)| substs.iter(Interner))
+            .filter_map(|arg| arg.ty(Interner).cloned())
+            .map(move |ty| self.derived(ty))
+    }
+
+    pub fn iterate_method_candidates<T>(
+        &self,
+        db: &dyn HirDatabase,
+        scope: &SemanticsScope<'_>,
+        // FIXME this can be retrieved from `scope`, except autoimport uses this
+        // to specify a different set, so the method needs to be split
+        traits_in_scope: &FxHashSet<TraitId>,
+        with_local_impls: Option<Module>,
+        name: Option<&Name>,
+        mut callback: impl FnMut(Function) -> Option<T>,
+    ) -> Option<T> {
+        let _p = profile::span("iterate_method_candidates");
+        let mut slot = None;
+
+        self.iterate_method_candidates_dyn(
+            db,
+            scope,
+            traits_in_scope,
+            with_local_impls,
+            name,
+            &mut |assoc_item_id| {
+                if let AssocItemId::FunctionId(func) = assoc_item_id {
+                    if let Some(res) = callback(func.into()) {
+                        slot = Some(res);
+                        return ControlFlow::Break(());
+                    }
+                }
+                ControlFlow::Continue(())
+            },
+        );
+        slot
+    }
+
+    fn iterate_method_candidates_dyn(
+        &self,
+        db: &dyn HirDatabase,
+        scope: &SemanticsScope<'_>,
+        traits_in_scope: &FxHashSet<TraitId>,
+        with_local_impls: Option<Module>,
+        name: Option<&Name>,
+        callback: &mut dyn FnMut(AssocItemId) -> ControlFlow<()>,
+    ) {
+        // There should be no inference vars in types passed here
+        let canonical = hir_ty::replace_errors_with_variables(&self.ty);
+
+        let krate = scope.krate();
+        let environment = scope.resolver().generic_def().map_or_else(
+            || Arc::new(TraitEnvironment::empty(krate.id)),
+            |d| db.trait_environment(d),
+        );
+
+        method_resolution::iterate_method_candidates_dyn(
+            &canonical,
+            db,
+            environment,
+            traits_in_scope,
+            with_local_impls.and_then(|b| b.id.containing_block()).into(),
+            name,
+            method_resolution::LookupMode::MethodCall,
+            &mut |_adj, id| callback(id),
+        );
+    }
+
+    pub fn iterate_path_candidates<T>(
+        &self,
+        db: &dyn HirDatabase,
+        scope: &SemanticsScope<'_>,
+        traits_in_scope: &FxHashSet<TraitId>,
+        with_local_impls: Option<Module>,
+        name: Option<&Name>,
+        mut callback: impl FnMut(AssocItem) -> Option<T>,
+    ) -> Option<T> {
+        let _p = profile::span("iterate_path_candidates");
+        let mut slot = None;
+        self.iterate_path_candidates_dyn(
+            db,
+            scope,
+            traits_in_scope,
+            with_local_impls,
+            name,
+            &mut |assoc_item_id| {
+                if let Some(res) = callback(assoc_item_id.into()) {
+                    slot = Some(res);
+                    return ControlFlow::Break(());
+                }
+                ControlFlow::Continue(())
+            },
+        );
+        slot
+    }
+
+    fn iterate_path_candidates_dyn(
+        &self,
+        db: &dyn HirDatabase,
+        scope: &SemanticsScope<'_>,
+        traits_in_scope: &FxHashSet<TraitId>,
+        with_local_impls: Option<Module>,
+        name: Option<&Name>,
+        callback: &mut dyn FnMut(AssocItemId) -> ControlFlow<()>,
+    ) {
+        let canonical = hir_ty::replace_errors_with_variables(&self.ty);
+
+        let krate = scope.krate();
+        let environment = scope.resolver().generic_def().map_or_else(
+            || Arc::new(TraitEnvironment::empty(krate.id)),
+            |d| db.trait_environment(d),
+        );
+
+        method_resolution::iterate_path_candidates(
+            &canonical,
+            db,
+            environment,
+            traits_in_scope,
+            with_local_impls.and_then(|b| b.id.containing_block()).into(),
+            name,
+            &mut |id| callback(id),
+        );
+    }
+
+    pub fn as_adt(&self) -> Option<Adt> {
+        let (adt, _subst) = self.ty.as_adt()?;
+        Some(adt.into())
+    }
+
+    pub fn as_builtin(&self) -> Option<BuiltinType> {
+        self.ty.as_builtin().map(|inner| BuiltinType { inner })
+    }
+
+    pub fn as_dyn_trait(&self) -> Option<Trait> {
+        self.ty.dyn_trait().map(Into::into)
+    }
+
+    /// If a type can be represented as `dyn Trait`, returns all traits accessible via this type,
+    /// or an empty iterator otherwise.
+    pub fn applicable_inherent_traits<'a>(
+        &'a self,
+        db: &'a dyn HirDatabase,
+    ) -> impl Iterator<Item = Trait> + 'a {
+        let _p = profile::span("applicable_inherent_traits");
+        self.autoderef_(db)
+            .filter_map(|ty| ty.dyn_trait())
+            .flat_map(move |dyn_trait_id| hir_ty::all_super_traits(db.upcast(), dyn_trait_id))
+            .map(Trait::from)
+    }
+
+    pub fn env_traits<'a>(&'a self, db: &'a dyn HirDatabase) -> impl Iterator<Item = Trait> + 'a {
+        let _p = profile::span("env_traits");
+        self.autoderef_(db)
+            .filter(|ty| matches!(ty.kind(Interner), TyKind::Placeholder(_)))
+            .flat_map(|ty| {
+                self.env
+                    .traits_in_scope_from_clauses(ty)
+                    .flat_map(|t| hir_ty::all_super_traits(db.upcast(), t))
+            })
+            .map(Trait::from)
+    }
+
+    pub fn as_impl_traits(&self, db: &dyn HirDatabase) -> Option<impl Iterator<Item = Trait>> {
+        self.ty.impl_trait_bounds(db).map(|it| {
+            it.into_iter().filter_map(|pred| match pred.skip_binders() {
+                hir_ty::WhereClause::Implemented(trait_ref) => {
+                    Some(Trait::from(trait_ref.hir_trait_id()))
+                }
+                _ => None,
+            })
+        })
+    }
+
+    pub fn as_associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<Trait> {
+        self.ty.associated_type_parent_trait(db).map(Into::into)
+    }
+
+    fn derived(&self, ty: Ty) -> Type {
+        Type { env: self.env.clone(), ty }
+    }
+
+    pub fn walk(&self, db: &dyn HirDatabase, mut cb: impl FnMut(Type)) {
+        // TypeWalk::walk for a Ty at first visits parameters and only after that the Ty itself.
+        // We need a different order here.
+
+        fn walk_substs(
+            db: &dyn HirDatabase,
+            type_: &Type,
+            substs: &Substitution,
+            cb: &mut impl FnMut(Type),
+        ) {
+            for ty in substs.iter(Interner).filter_map(|a| a.ty(Interner)) {
+                walk_type(db, &type_.derived(ty.clone()), cb);
+            }
+        }
+
+        fn walk_bounds(
+            db: &dyn HirDatabase,
+            type_: &Type,
+            bounds: &[QuantifiedWhereClause],
+            cb: &mut impl FnMut(Type),
+        ) {
+            for pred in bounds {
+                if let WhereClause::Implemented(trait_ref) = pred.skip_binders() {
+                    cb(type_.clone());
+                    // skip the self type. it's likely the type we just got the bounds from
+                    for ty in
+                        trait_ref.substitution.iter(Interner).skip(1).filter_map(|a| a.ty(Interner))
+                    {
+                        walk_type(db, &type_.derived(ty.clone()), cb);
+                    }
+                }
+            }
+        }
+
+        fn walk_type(db: &dyn HirDatabase, type_: &Type, cb: &mut impl FnMut(Type)) {
+            let ty = type_.ty.strip_references();
+            match ty.kind(Interner) {
+                TyKind::Adt(_, substs) => {
+                    cb(type_.derived(ty.clone()));
+                    walk_substs(db, type_, substs, cb);
+                }
+                TyKind::AssociatedType(_, substs) => {
+                    if ty.associated_type_parent_trait(db).is_some() {
+                        cb(type_.derived(ty.clone()));
+                    }
+                    walk_substs(db, type_, substs, cb);
+                }
+                TyKind::OpaqueType(_, subst) => {
+                    if let Some(bounds) = ty.impl_trait_bounds(db) {
+                        walk_bounds(db, &type_.derived(ty.clone()), &bounds, cb);
+                    }
+
+                    walk_substs(db, type_, subst, cb);
+                }
+                TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
+                    if let Some(bounds) = ty.impl_trait_bounds(db) {
+                        walk_bounds(db, &type_.derived(ty.clone()), &bounds, cb);
+                    }
+
+                    walk_substs(db, type_, &opaque_ty.substitution, cb);
+                }
+                TyKind::Placeholder(_) => {
+                    if let Some(bounds) = ty.impl_trait_bounds(db) {
+                        walk_bounds(db, &type_.derived(ty.clone()), &bounds, cb);
+                    }
+                }
+                TyKind::Dyn(bounds) => {
+                    walk_bounds(
+                        db,
+                        &type_.derived(ty.clone()),
+                        bounds.bounds.skip_binders().interned(),
+                        cb,
+                    );
+                }
+
+                TyKind::Ref(_, _, ty)
+                | TyKind::Raw(_, ty)
+                | TyKind::Array(ty, _)
+                | TyKind::Slice(ty) => {
+                    walk_type(db, &type_.derived(ty.clone()), cb);
+                }
+
+                TyKind::FnDef(_, substs)
+                | TyKind::Tuple(_, substs)
+                | TyKind::Closure(.., substs) => {
+                    walk_substs(db, type_, substs, cb);
+                }
+                TyKind::Function(hir_ty::FnPointer { substitution, .. }) => {
+                    walk_substs(db, type_, &substitution.0, cb);
+                }
+
+                _ => {}
+            }
+        }
+
+        walk_type(db, self, &mut cb);
+    }
+
+    pub fn could_unify_with(&self, db: &dyn HirDatabase, other: &Type) -> bool {
+        let tys = hir_ty::replace_errors_with_variables(&(self.ty.clone(), other.ty.clone()));
+        hir_ty::could_unify(db, self.env.clone(), &tys)
+    }
+
+    pub fn could_coerce_to(&self, db: &dyn HirDatabase, to: &Type) -> bool {
+        let tys = hir_ty::replace_errors_with_variables(&(self.ty.clone(), to.ty.clone()));
+        hir_ty::could_coerce(db, self.env.clone(), &tys)
+    }
+
+    pub fn as_type_param(&self, db: &dyn HirDatabase) -> Option<TypeParam> {
+        match self.ty.kind(Interner) {
+            TyKind::Placeholder(p) => Some(TypeParam {
+                id: TypeParamId::from_unchecked(hir_ty::from_placeholder_idx(db, *p)),
+            }),
+            _ => None,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Callable {
+    ty: Type,
+    sig: CallableSig,
+    callee: Callee,
+    pub(crate) is_bound_method: bool,
+}
+
+#[derive(Debug)]
+enum Callee {
+    Def(CallableDefId),
+    Closure(ClosureId),
+    FnPtr,
+}
+
+pub enum CallableKind {
+    Function(Function),
+    TupleStruct(Struct),
+    TupleEnumVariant(Variant),
+    Closure,
+    FnPtr,
+}
+
+impl Callable {
+    pub fn kind(&self) -> CallableKind {
+        use Callee::*;
+        match self.callee {
+            Def(CallableDefId::FunctionId(it)) => CallableKind::Function(it.into()),
+            Def(CallableDefId::StructId(it)) => CallableKind::TupleStruct(it.into()),
+            Def(CallableDefId::EnumVariantId(it)) => CallableKind::TupleEnumVariant(it.into()),
+            Closure(_) => CallableKind::Closure,
+            FnPtr => CallableKind::FnPtr,
+        }
+    }
+    pub fn receiver_param(&self, db: &dyn HirDatabase) -> Option<ast::SelfParam> {
+        let func = match self.callee {
+            Callee::Def(CallableDefId::FunctionId(it)) if self.is_bound_method => it,
+            _ => return None,
+        };
+        let src = func.lookup(db.upcast()).source(db.upcast());
+        let param_list = src.value.param_list()?;
+        param_list.self_param()
+    }
+    pub fn n_params(&self) -> usize {
+        self.sig.params().len() - if self.is_bound_method { 1 } else { 0 }
+    }
+    pub fn params(
+        &self,
+        db: &dyn HirDatabase,
+    ) -> Vec<(Option<Either<ast::SelfParam, ast::Pat>>, Type)> {
+        let types = self
+            .sig
+            .params()
+            .iter()
+            .skip(if self.is_bound_method { 1 } else { 0 })
+            .map(|ty| self.ty.derived(ty.clone()));
+        let map_param = |it: ast::Param| it.pat().map(Either::Right);
+        let patterns = match self.callee {
+            Callee::Def(CallableDefId::FunctionId(func)) => {
+                let src = func.lookup(db.upcast()).source(db.upcast());
+                src.value.param_list().map(|param_list| {
+                    param_list
+                        .self_param()
+                        .map(|it| Some(Either::Left(it)))
+                        .filter(|_| !self.is_bound_method)
+                        .into_iter()
+                        .chain(param_list.params().map(map_param))
+                })
+            }
+            Callee::Closure(closure_id) => match closure_source(db, closure_id) {
+                Some(src) => src.param_list().map(|param_list| {
+                    param_list
+                        .self_param()
+                        .map(|it| Some(Either::Left(it)))
+                        .filter(|_| !self.is_bound_method)
+                        .into_iter()
+                        .chain(param_list.params().map(map_param))
+                }),
+                None => None,
+            },
+            _ => None,
+        };
+        patterns.into_iter().flatten().chain(iter::repeat(None)).zip(types).collect()
+    }
+    pub fn return_type(&self) -> Type {
+        self.ty.derived(self.sig.ret().clone())
+    }
+}
+
+fn closure_source(db: &dyn HirDatabase, closure: ClosureId) -> Option<ast::ClosureExpr> {
+    let (owner, expr_id) = db.lookup_intern_closure(closure.into());
+    let (_, source_map) = db.body_with_source_map(owner);
+    let ast = source_map.expr_syntax(expr_id).ok()?;
+    let root = ast.file_syntax(db.upcast());
+    let expr = ast.value.to_node(&root);
+    match expr {
+        ast::Expr::ClosureExpr(it) => Some(it),
+        _ => None,
+    }
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum BindingMode {
+    Move,
+    Ref(Mutability),
+}
+
+/// For IDE only
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub enum ScopeDef {
+    ModuleDef(ModuleDef),
+    GenericParam(GenericParam),
+    ImplSelfType(Impl),
+    AdtSelfType(Adt),
+    Local(Local),
+    Label(Label),
+    Unknown,
+}
+
+impl ScopeDef {
+    pub fn all_items(def: PerNs) -> ArrayVec<Self, 3> {
+        let mut items = ArrayVec::new();
+
+        match (def.take_types(), def.take_values()) {
+            (Some(m1), None) => items.push(ScopeDef::ModuleDef(m1.into())),
+            (None, Some(m2)) => items.push(ScopeDef::ModuleDef(m2.into())),
+            (Some(m1), Some(m2)) => {
+                // Some items, like unit structs and enum variants, are
+                // returned as both a type and a value. Here we want
+                // to de-duplicate them.
+                if m1 != m2 {
+                    items.push(ScopeDef::ModuleDef(m1.into()));
+                    items.push(ScopeDef::ModuleDef(m2.into()));
+                } else {
+                    items.push(ScopeDef::ModuleDef(m1.into()));
+                }
+            }
+            (None, None) => {}
+        };
+
+        if let Some(macro_def_id) = def.take_macros() {
+            items.push(ScopeDef::ModuleDef(ModuleDef::Macro(macro_def_id.into())));
+        }
+
+        if items.is_empty() {
+            items.push(ScopeDef::Unknown);
+        }
+
+        items
+    }
+
+    pub fn attrs(&self, db: &dyn HirDatabase) -> Option<AttrsWithOwner> {
+        match self {
+            ScopeDef::ModuleDef(it) => it.attrs(db),
+            ScopeDef::GenericParam(it) => Some(it.attrs(db)),
+            ScopeDef::ImplSelfType(_)
+            | ScopeDef::AdtSelfType(_)
+            | ScopeDef::Local(_)
+            | ScopeDef::Label(_)
+            | ScopeDef::Unknown => None,
+        }
+    }
+
+    pub fn krate(&self, db: &dyn HirDatabase) -> Option<Crate> {
+        match self {
+            ScopeDef::ModuleDef(it) => it.module(db).map(|m| m.krate()),
+            ScopeDef::GenericParam(it) => Some(it.module(db).krate()),
+            ScopeDef::ImplSelfType(_) => None,
+            ScopeDef::AdtSelfType(it) => Some(it.module(db).krate()),
+            ScopeDef::Local(it) => Some(it.module(db).krate()),
+            ScopeDef::Label(it) => Some(it.module(db).krate()),
+            ScopeDef::Unknown => None,
+        }
+    }
+}
+
+impl From<ItemInNs> for ScopeDef {
+    fn from(item: ItemInNs) -> Self {
+        match item {
+            ItemInNs::Types(id) => ScopeDef::ModuleDef(id),
+            ItemInNs::Values(id) => ScopeDef::ModuleDef(id),
+            ItemInNs::Macros(id) => ScopeDef::ModuleDef(ModuleDef::Macro(id)),
+        }
+    }
+}
+
+pub trait HasVisibility {
+    fn visibility(&self, db: &dyn HirDatabase) -> Visibility;
+    fn is_visible_from(&self, db: &dyn HirDatabase, module: Module) -> bool {
+        let vis = self.visibility(db);
+        vis.is_visible_from(db.upcast(), module.id)
+    }
+}
+
+/// Trait for obtaining the defining crate of an item.
+pub trait HasCrate {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate;
+}
+
+impl<T: hir_def::HasModule> HasCrate for T {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db.upcast()).krate().into()
+    }
+}
+
+impl HasCrate for AssocItem {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Struct {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Union {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Field {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.parent_def(db).module(db).krate()
+    }
+}
+
+impl HasCrate for Variant {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Function {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Const {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for TypeAlias {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Type {
+    fn krate(&self, _db: &dyn HirDatabase) -> Crate {
+        self.env.krate.into()
+    }
+}
+
+impl HasCrate for Macro {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Trait {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Static {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Adt {
+    fn krate(&self, db: &dyn HirDatabase) -> Crate {
+        self.module(db).krate()
+    }
+}
+
+impl HasCrate for Module {
+    fn krate(&self, _: &dyn HirDatabase) -> Crate {
+        Module::krate(*self)
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/semantics.rs b/src/tools/rust-analyzer/crates/hir/src/semantics.rs
new file mode 100644
index 000000000..c84318b2f
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/semantics.rs
@@ -0,0 +1,1540 @@
+//! See `Semantics`.
+
+mod source_to_def;
+
+use std::{cell::RefCell, fmt, iter, ops};
+
+use base_db::{FileId, FileRange};
+use hir_def::{
+    body, macro_id_to_def_id,
+    resolver::{self, HasResolver, Resolver, TypeNs},
+    type_ref::Mutability,
+    AsMacroCall, FunctionId, MacroId, TraitId, VariantId,
+};
+use hir_expand::{
+    db::AstDatabase,
+    name::{known, AsName},
+    ExpansionInfo, MacroCallId,
+};
+use itertools::Itertools;
+use rustc_hash::{FxHashMap, FxHashSet};
+use smallvec::{smallvec, SmallVec};
+use syntax::{
+    algo::skip_trivia_token,
+    ast::{self, HasAttrs as _, HasGenericParams, HasLoopBody},
+    match_ast, AstNode, Direction, SyntaxKind, SyntaxNode, SyntaxNodePtr, SyntaxToken, TextSize,
+};
+
+use crate::{
+    db::HirDatabase,
+    semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
+    source_analyzer::{resolve_hir_path, SourceAnalyzer},
+    Access, BindingMode, BuiltinAttr, Callable, ConstParam, Crate, DeriveHelper, Field, Function,
+    HasSource, HirFileId, Impl, InFile, Label, LifetimeParam, Local, Macro, Module, ModuleDef,
+    Name, Path, ScopeDef, ToolModule, Trait, Type, TypeAlias, TypeParam, VariantDef,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum PathResolution {
+    /// An item
+    Def(ModuleDef),
+    /// A local binding (only value namespace)
+    Local(Local),
+    /// A type parameter
+    TypeParam(TypeParam),
+    /// A const parameter
+    ConstParam(ConstParam),
+    SelfType(Impl),
+    BuiltinAttr(BuiltinAttr),
+    ToolModule(ToolModule),
+    DeriveHelper(DeriveHelper),
+}
+
+impl PathResolution {
+    pub(crate) fn in_type_ns(&self) -> Option<TypeNs> {
+        match self {
+            PathResolution::Def(ModuleDef::Adt(adt)) => Some(TypeNs::AdtId((*adt).into())),
+            PathResolution::Def(ModuleDef::BuiltinType(builtin)) => {
+                Some(TypeNs::BuiltinType((*builtin).into()))
+            }
+            PathResolution::Def(
+                ModuleDef::Const(_)
+                | ModuleDef::Variant(_)
+                | ModuleDef::Macro(_)
+                | ModuleDef::Function(_)
+                | ModuleDef::Module(_)
+                | ModuleDef::Static(_)
+                | ModuleDef::Trait(_),
+            ) => None,
+            PathResolution::Def(ModuleDef::TypeAlias(alias)) => {
+                Some(TypeNs::TypeAliasId((*alias).into()))
+            }
+            PathResolution::BuiltinAttr(_)
+            | PathResolution::ToolModule(_)
+            | PathResolution::Local(_)
+            | PathResolution::DeriveHelper(_)
+            | PathResolution::ConstParam(_) => None,
+            PathResolution::TypeParam(param) => Some(TypeNs::GenericParam((*param).into())),
+            PathResolution::SelfType(impl_def) => Some(TypeNs::SelfType((*impl_def).into())),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct TypeInfo {
+    /// The original type of the expression or pattern.
+    pub original: Type,
+    /// The adjusted type, if an adjustment happened.
+    pub adjusted: Option<Type>,
+}
+
+impl TypeInfo {
+    pub fn original(self) -> Type {
+        self.original
+    }
+
+    pub fn has_adjustment(&self) -> bool {
+        self.adjusted.is_some()
+    }
+
+    /// The adjusted type, or the original in case no adjustments occurred.
+    pub fn adjusted(self) -> Type {
+        self.adjusted.unwrap_or(self.original)
+    }
+}
+
+/// Primary API to get semantic information, like types, from syntax trees.
+pub struct Semantics<'db, DB> {
+    pub db: &'db DB,
+    imp: SemanticsImpl<'db>,
+}
+
+pub struct SemanticsImpl<'db> {
+    pub db: &'db dyn HirDatabase,
+    s2d_cache: RefCell<SourceToDefCache>,
+    expansion_info_cache: RefCell<FxHashMap<HirFileId, Option<ExpansionInfo>>>,
+    // Rootnode to HirFileId cache
+    cache: RefCell<FxHashMap<SyntaxNode, HirFileId>>,
+    // MacroCall to its expansion's HirFileId cache
+    macro_call_cache: RefCell<FxHashMap<InFile<ast::MacroCall>, HirFileId>>,
+}
+
+impl<DB> fmt::Debug for Semantics<'_, DB> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Semantics {{ ... }}")
+    }
+}
+
+impl<'db, DB: HirDatabase> Semantics<'db, DB> {
+    pub fn new(db: &DB) -> Semantics<'_, DB> {
+        let impl_ = SemanticsImpl::new(db);
+        Semantics { db, imp: impl_ }
+    }
+
+    pub fn parse(&self, file_id: FileId) -> ast::SourceFile {
+        self.imp.parse(file_id)
+    }
+
+    pub fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode> {
+        self.imp.parse_or_expand(file_id)
+    }
+
+    pub fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+        self.imp.expand(macro_call)
+    }
+
+    /// If `item` has an attribute macro attached to it, expands it.
+    pub fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
+        self.imp.expand_attr_macro(item)
+    }
+
+    pub fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
+        self.imp.expand_derive_as_pseudo_attr_macro(attr)
+    }
+
+    pub fn resolve_derive_macro(&self, derive: &ast::Attr) -> Option<Vec<Option<Macro>>> {
+        self.imp.resolve_derive_macro(derive)
+    }
+
+    pub fn expand_derive_macro(&self, derive: &ast::Attr) -> Option<Vec<SyntaxNode>> {
+        self.imp.expand_derive_macro(derive)
+    }
+
+    pub fn is_attr_macro_call(&self, item: &ast::Item) -> bool {
+        self.imp.is_attr_macro_call(item)
+    }
+
+    pub fn is_derive_annotated(&self, item: &ast::Adt) -> bool {
+        self.imp.is_derive_annotated(item)
+    }
+
+    pub fn speculative_expand(
+        &self,
+        actual_macro_call: &ast::MacroCall,
+        speculative_args: &ast::TokenTree,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        self.imp.speculative_expand(actual_macro_call, speculative_args, token_to_map)
+    }
+
+    pub fn speculative_expand_attr_macro(
+        &self,
+        actual_macro_call: &ast::Item,
+        speculative_args: &ast::Item,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        self.imp.speculative_expand_attr(actual_macro_call, speculative_args, token_to_map)
+    }
+
+    pub fn speculative_expand_derive_as_pseudo_attr_macro(
+        &self,
+        actual_macro_call: &ast::Attr,
+        speculative_args: &ast::Attr,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        self.imp.speculative_expand_derive_as_pseudo_attr_macro(
+            actual_macro_call,
+            speculative_args,
+            token_to_map,
+        )
+    }
+
+    /// Descend the token into macrocalls to its first mapped counterpart.
+    pub fn descend_into_macros_single(&self, token: SyntaxToken) -> SyntaxToken {
+        self.imp.descend_into_macros_single(token)
+    }
+
+    /// Descend the token into macrocalls to all its mapped counterparts.
+    pub fn descend_into_macros(&self, token: SyntaxToken) -> SmallVec<[SyntaxToken; 1]> {
+        self.imp.descend_into_macros(token)
+    }
+
+    /// Descend the token into macrocalls to all its mapped counterparts that have the same text as the input token.
+    ///
+    /// Returns the original non descended token if none of the mapped counterparts have the same text.
+    pub fn descend_into_macros_with_same_text(
+        &self,
+        token: SyntaxToken,
+    ) -> SmallVec<[SyntaxToken; 1]> {
+        self.imp.descend_into_macros_with_same_text(token)
+    }
+
+    pub fn descend_into_macros_with_kind_preference(&self, token: SyntaxToken) -> SyntaxToken {
+        self.imp.descend_into_macros_with_kind_preference(token)
+    }
+
+    /// Maps a node down by mapping its first and last token down.
+    pub fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
+        self.imp.descend_node_into_attributes(node)
+    }
+
+    /// Search for a definition's source and cache its syntax tree
+    pub fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
+    where
+        Def::Ast: AstNode,
+    {
+        self.imp.source(def)
+    }
+
+    pub fn hir_file_for(&self, syntax_node: &SyntaxNode) -> HirFileId {
+        self.imp.find_file(syntax_node).file_id
+    }
+
+    /// Attempts to map the node out of macro expanded files returning the original file range.
+    /// If upmapping is not possible, this will fall back to the range of the macro call of the
+    /// macro file the node resides in.
+    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
+        self.imp.original_range(node)
+    }
+
+    /// Attempts to map the node out of macro expanded files returning the original file range.
+    pub fn original_range_opt(&self, node: &SyntaxNode) -> Option<FileRange> {
+        self.imp.original_range_opt(node)
+    }
+
+    /// Attempts to map the node out of macro expanded files.
+    /// This only work for attribute expansions, as other ones do not have nodes as input.
+    pub fn original_ast_node<N: AstNode>(&self, node: N) -> Option<N> {
+        self.imp.original_ast_node(node)
+    }
+
+    pub fn diagnostics_display_range(&self, diagnostics: InFile<SyntaxNodePtr>) -> FileRange {
+        self.imp.diagnostics_display_range(diagnostics)
+    }
+
+    pub fn token_ancestors_with_macros(
+        &self,
+        token: SyntaxToken,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        token.parent().into_iter().flat_map(move |it| self.ancestors_with_macros(it))
+    }
+
+    /// Iterates the ancestors of the given node, climbing up macro expansions while doing so.
+    pub fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
+        self.imp.ancestors_with_macros(node)
+    }
+
+    pub fn ancestors_at_offset_with_macros(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        self.imp.ancestors_at_offset_with_macros(node, offset)
+    }
+
+    /// Find an AstNode by offset inside SyntaxNode, if it is inside *Macrofile*,
+    /// search up until it is of the target AstNode type
+    pub fn find_node_at_offset_with_macros<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<N> {
+        self.imp.ancestors_at_offset_with_macros(node, offset).find_map(N::cast)
+    }
+
+    /// Find an AstNode by offset inside SyntaxNode, if it is inside *MacroCall*,
+    /// descend it and find again
+    pub fn find_node_at_offset_with_descend<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<N> {
+        self.imp.descend_node_at_offset(node, offset).flatten().find_map(N::cast)
+    }
+
+    /// Find an AstNode by offset inside SyntaxNode, if it is inside *MacroCall*,
+    /// descend it and find again
+    pub fn find_nodes_at_offset_with_descend<'slf, N: AstNode + 'slf>(
+        &'slf self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> impl Iterator<Item = N> + 'slf {
+        self.imp.descend_node_at_offset(node, offset).filter_map(|mut it| it.find_map(N::cast))
+    }
+
+    pub fn resolve_lifetime_param(&self, lifetime: &ast::Lifetime) -> Option<LifetimeParam> {
+        self.imp.resolve_lifetime_param(lifetime)
+    }
+
+    pub fn resolve_label(&self, lifetime: &ast::Lifetime) -> Option<Label> {
+        self.imp.resolve_label(lifetime)
+    }
+
+    pub fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
+        self.imp.resolve_type(ty)
+    }
+
+    pub fn resolve_trait(&self, trait_: &ast::Path) -> Option<Trait> {
+        self.imp.resolve_trait(trait_)
+    }
+
+    // FIXME: Figure out a nice interface to inspect adjustments
+    pub fn is_implicit_reborrow(&self, expr: &ast::Expr) -> Option<Mutability> {
+        self.imp.is_implicit_reborrow(expr)
+    }
+
+    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
+        self.imp.type_of_expr(expr)
+    }
+
+    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<TypeInfo> {
+        self.imp.type_of_pat(pat)
+    }
+
+    pub fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
+        self.imp.type_of_self(param)
+    }
+
+    pub fn pattern_adjustments(&self, pat: &ast::Pat) -> SmallVec<[Type; 1]> {
+        self.imp.pattern_adjustments(pat)
+    }
+
+    pub fn binding_mode_of_pat(&self, pat: &ast::IdentPat) -> Option<BindingMode> {
+        self.imp.binding_mode_of_pat(pat)
+    }
+
+    pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
+        self.imp.resolve_method_call(call).map(Function::from)
+    }
+
+    pub fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
+        self.imp.resolve_method_call_as_callable(call)
+    }
+
+    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
+        self.imp.resolve_field(field)
+    }
+
+    pub fn resolve_record_field(
+        &self,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>, Type)> {
+        self.imp.resolve_record_field(field)
+    }
+
+    pub fn resolve_record_pat_field(&self, field: &ast::RecordPatField) -> Option<Field> {
+        self.imp.resolve_record_pat_field(field)
+    }
+
+    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<Macro> {
+        self.imp.resolve_macro_call(macro_call)
+    }
+
+    pub fn is_unsafe_macro_call(&self, macro_call: &ast::MacroCall) -> bool {
+        self.imp.is_unsafe_macro_call(macro_call)
+    }
+
+    pub fn resolve_attr_macro_call(&self, item: &ast::Item) -> Option<Macro> {
+        self.imp.resolve_attr_macro_call(item)
+    }
+
+    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+        self.imp.resolve_path(path)
+    }
+
+    pub fn resolve_extern_crate(&self, extern_crate: &ast::ExternCrate) -> Option<Crate> {
+        self.imp.resolve_extern_crate(extern_crate)
+    }
+
+    pub fn resolve_variant(&self, record_lit: ast::RecordExpr) -> Option<VariantDef> {
+        self.imp.resolve_variant(record_lit).map(VariantDef::from)
+    }
+
+    pub fn resolve_bind_pat_to_const(&self, pat: &ast::IdentPat) -> Option<ModuleDef> {
+        self.imp.resolve_bind_pat_to_const(pat)
+    }
+
+    pub fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
+        self.imp.record_literal_missing_fields(literal)
+    }
+
+    pub fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
+        self.imp.record_pattern_missing_fields(pattern)
+    }
+
+    pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
+        let src = self.imp.find_file(src.syntax()).with_value(src).cloned();
+        T::to_def(&self.imp, src)
+    }
+
+    pub fn to_module_def(&self, file: FileId) -> Option<Module> {
+        self.imp.to_module_def(file).next()
+    }
+
+    pub fn to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module> {
+        self.imp.to_module_def(file)
+    }
+
+    pub fn scope(&self, node: &SyntaxNode) -> Option<SemanticsScope<'db>> {
+        self.imp.scope(node)
+    }
+
+    pub fn scope_at_offset(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<SemanticsScope<'db>> {
+        self.imp.scope_at_offset(node, offset)
+    }
+
+    pub fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db> {
+        self.imp.scope_for_def(def)
+    }
+
+    pub fn assert_contains_node(&self, node: &SyntaxNode) {
+        self.imp.assert_contains_node(node)
+    }
+
+    pub fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
+        self.imp.is_unsafe_method_call(method_call_expr)
+    }
+
+    pub fn is_unsafe_ref_expr(&self, ref_expr: &ast::RefExpr) -> bool {
+        self.imp.is_unsafe_ref_expr(ref_expr)
+    }
+
+    pub fn is_unsafe_ident_pat(&self, ident_pat: &ast::IdentPat) -> bool {
+        self.imp.is_unsafe_ident_pat(ident_pat)
+    }
+}
+
+impl<'db> SemanticsImpl<'db> {
+    fn new(db: &'db dyn HirDatabase) -> Self {
+        SemanticsImpl {
+            db,
+            s2d_cache: Default::default(),
+            cache: Default::default(),
+            expansion_info_cache: Default::default(),
+            macro_call_cache: Default::default(),
+        }
+    }
+
+    fn parse(&self, file_id: FileId) -> ast::SourceFile {
+        let tree = self.db.parse(file_id).tree();
+        self.cache(tree.syntax().clone(), file_id.into());
+        tree
+    }
+
+    fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode> {
+        let node = self.db.parse_or_expand(file_id)?;
+        self.cache(node.clone(), file_id);
+        Some(node)
+    }
+
+    fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+        let sa = self.analyze_no_infer(macro_call.syntax())?;
+        let file_id = sa.expand(self.db, InFile::new(sa.file_id, macro_call))?;
+        let node = self.parse_or_expand(file_id)?;
+        Some(node)
+    }
+
+    fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
+        let src = self.wrap_node_infile(item.clone());
+        let macro_call_id = self.with_ctx(|ctx| ctx.item_to_macro_call(src))?;
+        self.parse_or_expand(macro_call_id.as_file())
+    }
+
+    fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
+        let src = self.wrap_node_infile(attr.clone());
+        let adt = attr.syntax().parent().and_then(ast::Adt::cast)?;
+        let call_id = self.with_ctx(|ctx| {
+            ctx.attr_to_derive_macro_call(src.with_value(&adt), src).map(|(_, it, _)| it)
+        })?;
+        self.parse_or_expand(call_id.as_file())
+    }
+
+    fn resolve_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<Option<Macro>>> {
+        let calls = self.derive_macro_calls(attr)?;
+        self.with_ctx(|ctx| {
+            Some(
+                calls
+                    .into_iter()
+                    .map(|call| {
+                        macro_call_to_macro_id(ctx, self.db.upcast(), call?).map(|id| Macro { id })
+                    })
+                    .collect(),
+            )
+        })
+    }
+
+    fn expand_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<SyntaxNode>> {
+        let res: Vec<_> = self
+            .derive_macro_calls(attr)?
+            .into_iter()
+            .flat_map(|call| {
+                let file_id = call?.as_file();
+                let node = self.db.parse_or_expand(file_id)?;
+                self.cache(node.clone(), file_id);
+                Some(node)
+            })
+            .collect();
+        Some(res)
+    }
+
+    fn derive_macro_calls(&self, attr: &ast::Attr) -> Option<Vec<Option<MacroCallId>>> {
+        let adt = attr.syntax().parent().and_then(ast::Adt::cast)?;
+        let file_id = self.find_file(adt.syntax()).file_id;
+        let adt = InFile::new(file_id, &adt);
+        let src = InFile::new(file_id, attr.clone());
+        self.with_ctx(|ctx| {
+            let (.., res) = ctx.attr_to_derive_macro_call(adt, src)?;
+            Some(res.to_vec())
+        })
+    }
+
+    fn is_derive_annotated(&self, adt: &ast::Adt) -> bool {
+        let file_id = self.find_file(adt.syntax()).file_id;
+        let adt = InFile::new(file_id, adt);
+        self.with_ctx(|ctx| ctx.has_derives(adt))
+    }
+
+    fn is_attr_macro_call(&self, item: &ast::Item) -> bool {
+        let file_id = self.find_file(item.syntax()).file_id;
+        let src = InFile::new(file_id, item.clone());
+        self.with_ctx(|ctx| ctx.item_to_macro_call(src).is_some())
+    }
+
+    fn speculative_expand(
+        &self,
+        actual_macro_call: &ast::MacroCall,
+        speculative_args: &ast::TokenTree,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let SourceAnalyzer { file_id, resolver, .. } =
+            self.analyze_no_infer(actual_macro_call.syntax())?;
+        let macro_call = InFile::new(file_id, actual_macro_call);
+        let krate = resolver.krate();
+        let macro_call_id = macro_call.as_call_id(self.db.upcast(), krate, |path| {
+            resolver
+                .resolve_path_as_macro(self.db.upcast(), &path)
+                .map(|it| macro_id_to_def_id(self.db.upcast(), it))
+        })?;
+        hir_expand::db::expand_speculative(
+            self.db.upcast(),
+            macro_call_id,
+            speculative_args.syntax(),
+            token_to_map,
+        )
+    }
+
+    fn speculative_expand_attr(
+        &self,
+        actual_macro_call: &ast::Item,
+        speculative_args: &ast::Item,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let macro_call = self.wrap_node_infile(actual_macro_call.clone());
+        let macro_call_id = self.with_ctx(|ctx| ctx.item_to_macro_call(macro_call))?;
+        hir_expand::db::expand_speculative(
+            self.db.upcast(),
+            macro_call_id,
+            speculative_args.syntax(),
+            token_to_map,
+        )
+    }
+
+    fn speculative_expand_derive_as_pseudo_attr_macro(
+        &self,
+        actual_macro_call: &ast::Attr,
+        speculative_args: &ast::Attr,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let attr = self.wrap_node_infile(actual_macro_call.clone());
+        let adt = actual_macro_call.syntax().parent().and_then(ast::Adt::cast)?;
+        let macro_call_id = self.with_ctx(|ctx| {
+            ctx.attr_to_derive_macro_call(attr.with_value(&adt), attr).map(|(_, it, _)| it)
+        })?;
+        hir_expand::db::expand_speculative(
+            self.db.upcast(),
+            macro_call_id,
+            speculative_args.syntax(),
+            token_to_map,
+        )
+    }
+
+    // This might not be the correct way to do this, but it works for now
+    fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
+        let mut res = smallvec![];
+        let tokens = (|| {
+            let first = skip_trivia_token(node.syntax().first_token()?, Direction::Next)?;
+            let last = skip_trivia_token(node.syntax().last_token()?, Direction::Prev)?;
+            Some((first, last))
+        })();
+        let (first, last) = match tokens {
+            Some(it) => it,
+            None => return res,
+        };
+
+        if first == last {
+            self.descend_into_macros_impl(first, &mut |InFile { value, .. }| {
+                if let Some(node) = value.parent_ancestors().find_map(N::cast) {
+                    res.push(node)
+                }
+                false
+            });
+        } else {
+            // Descend first and last token, then zip them to look for the node they belong to
+            let mut scratch: SmallVec<[_; 1]> = smallvec![];
+            self.descend_into_macros_impl(first, &mut |token| {
+                scratch.push(token);
+                false
+            });
+
+            let mut scratch = scratch.into_iter();
+            self.descend_into_macros_impl(
+                last,
+                &mut |InFile { value: last, file_id: last_fid }| {
+                    if let Some(InFile { value: first, file_id: first_fid }) = scratch.next() {
+                        if first_fid == last_fid {
+                            if let Some(p) = first.parent() {
+                                let range = first.text_range().cover(last.text_range());
+                                let node = find_root(&p)
+                                    .covering_element(range)
+                                    .ancestors()
+                                    .take_while(|it| it.text_range() == range)
+                                    .find_map(N::cast);
+                                if let Some(node) = node {
+                                    res.push(node);
+                                }
+                            }
+                        }
+                    }
+                    false
+                },
+            );
+        }
+        res
+    }
+
+    fn descend_into_macros(&self, token: SyntaxToken) -> SmallVec<[SyntaxToken; 1]> {
+        let mut res = smallvec![];
+        self.descend_into_macros_impl(token, &mut |InFile { value, .. }| {
+            res.push(value);
+            false
+        });
+        res
+    }
+
+    fn descend_into_macros_with_same_text(&self, token: SyntaxToken) -> SmallVec<[SyntaxToken; 1]> {
+        let text = token.text();
+        let mut res = smallvec![];
+        self.descend_into_macros_impl(token.clone(), &mut |InFile { value, .. }| {
+            if value.text() == text {
+                res.push(value);
+            }
+            false
+        });
+        if res.is_empty() {
+            res.push(token);
+        }
+        res
+    }
+
+    fn descend_into_macros_with_kind_preference(&self, token: SyntaxToken) -> SyntaxToken {
+        let fetch_kind = |token: &SyntaxToken| match token.parent() {
+            Some(node) => match node.kind() {
+                kind @ (SyntaxKind::NAME | SyntaxKind::NAME_REF) => {
+                    node.parent().map_or(kind, |it| it.kind())
+                }
+                _ => token.kind(),
+            },
+            None => token.kind(),
+        };
+        let preferred_kind = fetch_kind(&token);
+        let mut res = None;
+        self.descend_into_macros_impl(token.clone(), &mut |InFile { value, .. }| {
+            if fetch_kind(&value) == preferred_kind {
+                res = Some(value);
+                true
+            } else {
+                if let None = res {
+                    res = Some(value)
+                }
+                false
+            }
+        });
+        res.unwrap_or(token)
+    }
+
+    fn descend_into_macros_single(&self, token: SyntaxToken) -> SyntaxToken {
+        let mut res = token.clone();
+        self.descend_into_macros_impl(token, &mut |InFile { value, .. }| {
+            res = value;
+            true
+        });
+        res
+    }
+
+    fn descend_into_macros_impl(
+        &self,
+        token: SyntaxToken,
+        f: &mut dyn FnMut(InFile<SyntaxToken>) -> bool,
+    ) {
+        let _p = profile::span("descend_into_macros");
+        let parent = match token.parent() {
+            Some(it) => it,
+            None => return,
+        };
+        let sa = match self.analyze_no_infer(&parent) {
+            Some(it) => it,
+            None => return,
+        };
+        let def_map = sa.resolver.def_map();
+
+        let mut stack: SmallVec<[_; 4]> = smallvec![InFile::new(sa.file_id, token)];
+        let mut cache = self.expansion_info_cache.borrow_mut();
+        let mut mcache = self.macro_call_cache.borrow_mut();
+
+        let mut process_expansion_for_token =
+            |stack: &mut SmallVec<_>, macro_file, item, token: InFile<&_>| {
+                let expansion_info = cache
+                    .entry(macro_file)
+                    .or_insert_with(|| macro_file.expansion_info(self.db.upcast()))
+                    .as_ref()?;
+
+                {
+                    let InFile { file_id, value } = expansion_info.expanded();
+                    self.cache(value, file_id);
+                }
+
+                let mapped_tokens = expansion_info.map_token_down(self.db.upcast(), item, token)?;
+                let len = stack.len();
+
+                // requeue the tokens we got from mapping our current token down
+                stack.extend(mapped_tokens);
+                // if the length changed we have found a mapping for the token
+                (stack.len() != len).then(|| ())
+            };
+
+        // Remap the next token in the queue into a macro call its in, if it is not being remapped
+        // either due to not being in a macro-call or because its unused push it into the result vec,
+        // otherwise push the remapped tokens back into the queue as they can potentially be remapped again.
+        while let Some(token) = stack.pop() {
+            self.db.unwind_if_cancelled();
+            let was_not_remapped = (|| {
+                // First expand into attribute invocations
+                let containing_attribute_macro_call = self.with_ctx(|ctx| {
+                    token.value.parent_ancestors().filter_map(ast::Item::cast).find_map(|item| {
+                        if item.attrs().next().is_none() {
+                            // Don't force populate the dyn cache for items that don't have an attribute anyways
+                            return None;
+                        }
+                        Some((ctx.item_to_macro_call(token.with_value(item.clone()))?, item))
+                    })
+                });
+                if let Some((call_id, item)) = containing_attribute_macro_call {
+                    let file_id = call_id.as_file();
+                    return process_expansion_for_token(
+                        &mut stack,
+                        file_id,
+                        Some(item),
+                        token.as_ref(),
+                    );
+                }
+
+                // Then check for token trees, that means we are either in a function-like macro or
+                // secondary attribute inputs
+                let tt = token.value.parent_ancestors().map_while(ast::TokenTree::cast).last()?;
+                let parent = tt.syntax().parent()?;
+
+                if tt.left_delimiter_token().map_or(false, |it| it == token.value) {
+                    return None;
+                }
+                if tt.right_delimiter_token().map_or(false, |it| it == token.value) {
+                    return None;
+                }
+
+                if let Some(macro_call) = ast::MacroCall::cast(parent.clone()) {
+                    let mcall = token.with_value(macro_call);
+                    let file_id = match mcache.get(&mcall) {
+                        Some(&it) => it,
+                        None => {
+                            let it = sa.expand(self.db, mcall.as_ref())?;
+                            mcache.insert(mcall, it);
+                            it
+                        }
+                    };
+                    process_expansion_for_token(&mut stack, file_id, None, token.as_ref())
+                } else if let Some(meta) = ast::Meta::cast(parent.clone()) {
+                    // attribute we failed expansion for earlier, this might be a derive invocation
+                    // or derive helper attribute
+                    let attr = meta.parent_attr()?;
+
+                    let adt = if let Some(adt) = attr.syntax().parent().and_then(ast::Adt::cast) {
+                        // this might be a derive, or a derive helper on an ADT
+                        let derive_call = self.with_ctx(|ctx| {
+                            // so try downmapping the token into the pseudo derive expansion
+                            // see [hir_expand::builtin_attr_macro] for how the pseudo derive expansion works
+                            ctx.attr_to_derive_macro_call(
+                                token.with_value(&adt),
+                                token.with_value(attr.clone()),
+                            )
+                            .map(|(_, call_id, _)| call_id)
+                        });
+
+                        match derive_call {
+                            Some(call_id) => {
+                                // resolved to a derive
+                                let file_id = call_id.as_file();
+                                return process_expansion_for_token(
+                                    &mut stack,
+                                    file_id,
+                                    Some(adt.into()),
+                                    token.as_ref(),
+                                );
+                            }
+                            None => Some(adt),
+                        }
+                    } else {
+                        // Otherwise this could be a derive helper on a variant or field
+                        if let Some(field) = attr.syntax().parent().and_then(ast::RecordField::cast)
+                        {
+                            field.syntax().ancestors().take(4).find_map(ast::Adt::cast)
+                        } else if let Some(field) =
+                            attr.syntax().parent().and_then(ast::TupleField::cast)
+                        {
+                            field.syntax().ancestors().take(4).find_map(ast::Adt::cast)
+                        } else if let Some(variant) =
+                            attr.syntax().parent().and_then(ast::Variant::cast)
+                        {
+                            variant.syntax().ancestors().nth(2).and_then(ast::Adt::cast)
+                        } else {
+                            None
+                        }
+                    }?;
+                    if !self.with_ctx(|ctx| ctx.has_derives(InFile::new(token.file_id, &adt))) {
+                        return None;
+                    }
+                    // Not an attribute, nor a derive, so it's either a builtin or a derive helper
+                    // Try to resolve to a derive helper and downmap
+                    let attr_name = attr.path().and_then(|it| it.as_single_name_ref())?.as_name();
+                    let id = self.db.ast_id_map(token.file_id).ast_id(&adt);
+                    let helpers =
+                        def_map.derive_helpers_in_scope(InFile::new(token.file_id, id))?;
+                    let item = Some(adt.into());
+                    let mut res = None;
+                    for (.., derive) in helpers.iter().filter(|(helper, ..)| *helper == attr_name) {
+                        res = res.or(process_expansion_for_token(
+                            &mut stack,
+                            derive.as_file(),
+                            item.clone(),
+                            token.as_ref(),
+                        ));
+                    }
+                    res
+                } else {
+                    None
+                }
+            })()
+            .is_none();
+
+            if was_not_remapped && f(token) {
+                break;
+            }
+        }
+    }
+
+    // Note this return type is deliberate as [`find_nodes_at_offset_with_descend`] wants to stop
+    // traversing the inner iterator when it finds a node.
+    // The outer iterator is over the tokens descendants
+    // The inner iterator is the ancestors of a descendant
+    fn descend_node_at_offset(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> impl Iterator<Item = impl Iterator<Item = SyntaxNode> + '_> + '_ {
+        node.token_at_offset(offset)
+            .map(move |token| self.descend_into_macros(token))
+            .map(|descendants| {
+                descendants.into_iter().map(move |it| self.token_ancestors_with_macros(it))
+            })
+            // re-order the tokens from token_at_offset by returning the ancestors with the smaller first nodes first
+            // See algo::ancestors_at_offset, which uses the same approach
+            .kmerge_by(|left, right| {
+                left.clone()
+                    .map(|node| node.text_range().len())
+                    .lt(right.clone().map(|node| node.text_range().len()))
+            })
+    }
+
+    fn original_range(&self, node: &SyntaxNode) -> FileRange {
+        let node = self.find_file(node);
+        node.original_file_range(self.db.upcast())
+    }
+
+    fn original_range_opt(&self, node: &SyntaxNode) -> Option<FileRange> {
+        let node = self.find_file(node);
+        node.original_file_range_opt(self.db.upcast())
+    }
+
+    fn original_ast_node<N: AstNode>(&self, node: N) -> Option<N> {
+        self.wrap_node_infile(node).original_ast_node(self.db.upcast()).map(
+            |InFile { file_id, value }| {
+                self.cache(find_root(value.syntax()), file_id);
+                value
+            },
+        )
+    }
+
+    fn diagnostics_display_range(&self, src: InFile<SyntaxNodePtr>) -> FileRange {
+        let root = self.parse_or_expand(src.file_id).unwrap();
+        let node = src.map(|it| it.to_node(&root));
+        node.as_ref().original_file_range(self.db.upcast())
+    }
+
+    fn token_ancestors_with_macros(
+        &self,
+        token: SyntaxToken,
+    ) -> impl Iterator<Item = SyntaxNode> + Clone + '_ {
+        token.parent().into_iter().flat_map(move |parent| self.ancestors_with_macros(parent))
+    }
+
+    fn ancestors_with_macros(
+        &self,
+        node: SyntaxNode,
+    ) -> impl Iterator<Item = SyntaxNode> + Clone + '_ {
+        let node = self.find_file(&node);
+        let db = self.db.upcast();
+        iter::successors(Some(node.cloned()), move |&InFile { file_id, ref value }| {
+            match value.parent() {
+                Some(parent) => Some(InFile::new(file_id, parent)),
+                None => {
+                    self.cache(value.clone(), file_id);
+                    file_id.call_node(db)
+                }
+            }
+        })
+        .map(|it| it.value)
+    }
+
+    fn ancestors_at_offset_with_macros(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        node.token_at_offset(offset)
+            .map(|token| self.token_ancestors_with_macros(token))
+            .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
+    }
+
+    fn resolve_lifetime_param(&self, lifetime: &ast::Lifetime) -> Option<LifetimeParam> {
+        let text = lifetime.text();
+        let lifetime_param = lifetime.syntax().ancestors().find_map(|syn| {
+            let gpl = ast::AnyHasGenericParams::cast(syn)?.generic_param_list()?;
+            gpl.lifetime_params()
+                .find(|tp| tp.lifetime().as_ref().map(|lt| lt.text()).as_ref() == Some(&text))
+        })?;
+        let src = self.wrap_node_infile(lifetime_param);
+        ToDef::to_def(self, src)
+    }
+
+    fn resolve_label(&self, lifetime: &ast::Lifetime) -> Option<Label> {
+        let text = lifetime.text();
+        let label = lifetime.syntax().ancestors().find_map(|syn| {
+            let label = match_ast! {
+                match syn {
+                    ast::ForExpr(it) => it.label(),
+                    ast::WhileExpr(it) => it.label(),
+                    ast::LoopExpr(it) => it.label(),
+                    ast::BlockExpr(it) => it.label(),
+                    _ => None,
+                }
+            };
+            label.filter(|l| {
+                l.lifetime()
+                    .and_then(|lt| lt.lifetime_ident_token())
+                    .map_or(false, |lt| lt.text() == text)
+            })
+        })?;
+        let src = self.wrap_node_infile(label);
+        ToDef::to_def(self, src)
+    }
+
+    fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
+        let analyze = self.analyze(ty.syntax())?;
+        let ctx = body::LowerCtx::new(self.db.upcast(), analyze.file_id);
+        let ty = hir_ty::TyLoweringContext::new(self.db, &analyze.resolver)
+            .lower_ty(&crate::TypeRef::from_ast(&ctx, ty.clone()));
+        Some(Type::new_with_resolver(self.db, &analyze.resolver, ty))
+    }
+
+    fn resolve_trait(&self, path: &ast::Path) -> Option<Trait> {
+        let analyze = self.analyze(path.syntax())?;
+        let hygiene = hir_expand::hygiene::Hygiene::new(self.db.upcast(), analyze.file_id);
+        let ctx = body::LowerCtx::with_hygiene(self.db.upcast(), &hygiene);
+        let hir_path = Path::from_src(path.clone(), &ctx)?;
+        match analyze
+            .resolver
+            .resolve_path_in_type_ns_fully(self.db.upcast(), hir_path.mod_path())?
+        {
+            TypeNs::TraitId(id) => Some(Trait { id }),
+            _ => None,
+        }
+    }
+
+    fn is_implicit_reborrow(&self, expr: &ast::Expr) -> Option<Mutability> {
+        self.analyze(expr.syntax())?.is_implicit_reborrow(self.db, expr)
+    }
+
+    fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
+        self.analyze(expr.syntax())?
+            .type_of_expr(self.db, expr)
+            .map(|(ty, coerced)| TypeInfo { original: ty, adjusted: coerced })
+    }
+
+    fn type_of_pat(&self, pat: &ast::Pat) -> Option<TypeInfo> {
+        self.analyze(pat.syntax())?
+            .type_of_pat(self.db, pat)
+            .map(|(ty, coerced)| TypeInfo { original: ty, adjusted: coerced })
+    }
+
+    fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
+        self.analyze(param.syntax())?.type_of_self(self.db, param)
+    }
+
+    fn pattern_adjustments(&self, pat: &ast::Pat) -> SmallVec<[Type; 1]> {
+        self.analyze(pat.syntax())
+            .and_then(|it| it.pattern_adjustments(self.db, pat))
+            .unwrap_or_default()
+    }
+
+    fn binding_mode_of_pat(&self, pat: &ast::IdentPat) -> Option<BindingMode> {
+        self.analyze(pat.syntax())?.binding_mode_of_pat(self.db, pat)
+    }
+
+    fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
+        self.analyze(call.syntax())?.resolve_method_call(self.db, call)
+    }
+
+    fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
+        self.analyze(call.syntax())?.resolve_method_call_as_callable(self.db, call)
+    }
+
+    fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
+        self.analyze(field.syntax())?.resolve_field(self.db, field)
+    }
+
+    fn resolve_record_field(
+        &self,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>, Type)> {
+        self.analyze(field.syntax())?.resolve_record_field(self.db, field)
+    }
+
+    fn resolve_record_pat_field(&self, field: &ast::RecordPatField) -> Option<Field> {
+        self.analyze(field.syntax())?.resolve_record_pat_field(self.db, field)
+    }
+
+    fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<Macro> {
+        let sa = self.analyze(macro_call.syntax())?;
+        let macro_call = self.find_file(macro_call.syntax()).with_value(macro_call);
+        sa.resolve_macro_call(self.db, macro_call)
+    }
+
+    fn is_unsafe_macro_call(&self, macro_call: &ast::MacroCall) -> bool {
+        let sa = match self.analyze(macro_call.syntax()) {
+            Some(it) => it,
+            None => return false,
+        };
+        let macro_call = self.find_file(macro_call.syntax()).with_value(macro_call);
+        sa.is_unsafe_macro_call(self.db, macro_call)
+    }
+
+    fn resolve_attr_macro_call(&self, item: &ast::Item) -> Option<Macro> {
+        let item_in_file = self.wrap_node_infile(item.clone());
+        let id = self.with_ctx(|ctx| {
+            let macro_call_id = ctx.item_to_macro_call(item_in_file)?;
+            macro_call_to_macro_id(ctx, self.db.upcast(), macro_call_id)
+        })?;
+        Some(Macro { id })
+    }
+
+    fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+        self.analyze(path.syntax())?.resolve_path(self.db, path)
+    }
+
+    fn resolve_extern_crate(&self, extern_crate: &ast::ExternCrate) -> Option<Crate> {
+        let krate = self.scope(extern_crate.syntax())?.krate();
+        let name = extern_crate.name_ref()?.as_name();
+        if name == known::SELF_PARAM {
+            return Some(krate);
+        }
+        krate
+            .dependencies(self.db)
+            .into_iter()
+            .find_map(|dep| (dep.name == name).then(|| dep.krate))
+    }
+
+    fn resolve_variant(&self, record_lit: ast::RecordExpr) -> Option<VariantId> {
+        self.analyze(record_lit.syntax())?.resolve_variant(self.db, record_lit)
+    }
+
+    fn resolve_bind_pat_to_const(&self, pat: &ast::IdentPat) -> Option<ModuleDef> {
+        self.analyze(pat.syntax())?.resolve_bind_pat_to_const(self.db, pat)
+    }
+
+    fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
+        self.analyze(literal.syntax())
+            .and_then(|it| it.record_literal_missing_fields(self.db, literal))
+            .unwrap_or_default()
+    }
+
+    fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
+        self.analyze(pattern.syntax())
+            .and_then(|it| it.record_pattern_missing_fields(self.db, pattern))
+            .unwrap_or_default()
+    }
+
+    fn with_ctx<F: FnOnce(&mut SourceToDefCtx<'_, '_>) -> T, T>(&self, f: F) -> T {
+        let mut cache = self.s2d_cache.borrow_mut();
+        let mut ctx = SourceToDefCtx { db: self.db, cache: &mut *cache };
+        f(&mut ctx)
+    }
+
+    fn to_module_def(&self, file: FileId) -> impl Iterator<Item = Module> {
+        self.with_ctx(|ctx| ctx.file_to_def(file)).into_iter().map(Module::from)
+    }
+
+    fn scope(&self, node: &SyntaxNode) -> Option<SemanticsScope<'db>> {
+        self.analyze_no_infer(node).map(|SourceAnalyzer { file_id, resolver, .. }| SemanticsScope {
+            db: self.db,
+            file_id,
+            resolver,
+        })
+    }
+
+    fn scope_at_offset(&self, node: &SyntaxNode, offset: TextSize) -> Option<SemanticsScope<'db>> {
+        self.analyze_with_offset_no_infer(node, offset).map(
+            |SourceAnalyzer { file_id, resolver, .. }| SemanticsScope {
+                db: self.db,
+                file_id,
+                resolver,
+            },
+        )
+    }
+
+    fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db> {
+        let file_id = self.db.lookup_intern_trait(def.id).id.file_id();
+        let resolver = def.id.resolver(self.db.upcast());
+        SemanticsScope { db: self.db, file_id, resolver }
+    }
+
+    fn source<Def: HasSource>(&self, def: Def) -> Option<InFile<Def::Ast>>
+    where
+        Def::Ast: AstNode,
+    {
+        let res = def.source(self.db)?;
+        self.cache(find_root(res.value.syntax()), res.file_id);
+        Some(res)
+    }
+
+    /// Returns none if the file of the node is not part of a crate.
+    fn analyze(&self, node: &SyntaxNode) -> Option<SourceAnalyzer> {
+        self.analyze_impl(node, None, true)
+    }
+
+    /// Returns none if the file of the node is not part of a crate.
+    fn analyze_no_infer(&self, node: &SyntaxNode) -> Option<SourceAnalyzer> {
+        self.analyze_impl(node, None, false)
+    }
+
+    fn analyze_with_offset_no_infer(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<SourceAnalyzer> {
+        self.analyze_impl(node, Some(offset), false)
+    }
+
+    fn analyze_impl(
+        &self,
+        node: &SyntaxNode,
+        offset: Option<TextSize>,
+        infer_body: bool,
+    ) -> Option<SourceAnalyzer> {
+        let _p = profile::span("Semantics::analyze_impl");
+        let node = self.find_file(node);
+
+        let container = match self.with_ctx(|ctx| ctx.find_container(node)) {
+            Some(it) => it,
+            None => return None,
+        };
+
+        let resolver = match container {
+            ChildContainer::DefWithBodyId(def) => {
+                return Some(if infer_body {
+                    SourceAnalyzer::new_for_body(self.db, def, node, offset)
+                } else {
+                    SourceAnalyzer::new_for_body_no_infer(self.db, def, node, offset)
+                })
+            }
+            ChildContainer::TraitId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::ImplId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::ModuleId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::EnumId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::VariantId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::TypeAliasId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::GenericDefId(it) => it.resolver(self.db.upcast()),
+        };
+        Some(SourceAnalyzer::new_for_resolver(resolver, node))
+    }
+
+    fn cache(&self, root_node: SyntaxNode, file_id: HirFileId) {
+        assert!(root_node.parent().is_none());
+        let mut cache = self.cache.borrow_mut();
+        let prev = cache.insert(root_node, file_id);
+        assert!(prev == None || prev == Some(file_id))
+    }
+
+    fn assert_contains_node(&self, node: &SyntaxNode) {
+        self.find_file(node);
+    }
+
+    fn lookup(&self, root_node: &SyntaxNode) -> Option<HirFileId> {
+        let cache = self.cache.borrow();
+        cache.get(root_node).copied()
+    }
+
+    fn wrap_node_infile<N: AstNode>(&self, node: N) -> InFile<N> {
+        let InFile { file_id, .. } = self.find_file(node.syntax());
+        InFile::new(file_id, node)
+    }
+
+    /// Wraps the node in a [`InFile`] with the file id it belongs to.
+    fn find_file<'node>(&self, node: &'node SyntaxNode) -> InFile<&'node SyntaxNode> {
+        let root_node = find_root(node);
+        let file_id = self.lookup(&root_node).unwrap_or_else(|| {
+            panic!(
+                "\n\nFailed to lookup {:?} in this Semantics.\n\
+                 Make sure to use only query nodes, derived from this instance of Semantics.\n\
+                 root node:   {:?}\n\
+                 known nodes: {}\n\n",
+                node,
+                root_node,
+                self.cache
+                    .borrow()
+                    .keys()
+                    .map(|it| format!("{:?}", it))
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            )
+        });
+        InFile::new(file_id, node)
+    }
+
+    fn is_unsafe_method_call(&self, method_call_expr: &ast::MethodCallExpr) -> bool {
+        method_call_expr
+            .receiver()
+            .and_then(|expr| {
+                let field_expr = match expr {
+                    ast::Expr::FieldExpr(field_expr) => field_expr,
+                    _ => return None,
+                };
+                let ty = self.type_of_expr(&field_expr.expr()?)?.original;
+                if !ty.is_packed(self.db) {
+                    return None;
+                }
+
+                let func = self.resolve_method_call(method_call_expr).map(Function::from)?;
+                let res = match func.self_param(self.db)?.access(self.db) {
+                    Access::Shared | Access::Exclusive => true,
+                    Access::Owned => false,
+                };
+                Some(res)
+            })
+            .unwrap_or(false)
+    }
+
+    fn is_unsafe_ref_expr(&self, ref_expr: &ast::RefExpr) -> bool {
+        ref_expr
+            .expr()
+            .and_then(|expr| {
+                let field_expr = match expr {
+                    ast::Expr::FieldExpr(field_expr) => field_expr,
+                    _ => return None,
+                };
+                let expr = field_expr.expr()?;
+                self.type_of_expr(&expr)
+            })
+            // Binding a reference to a packed type is possibly unsafe.
+            .map(|ty| ty.original.is_packed(self.db))
+            .unwrap_or(false)
+
+        // FIXME This needs layout computation to be correct. It will highlight
+        // more than it should with the current implementation.
+    }
+
+    fn is_unsafe_ident_pat(&self, ident_pat: &ast::IdentPat) -> bool {
+        if ident_pat.ref_token().is_none() {
+            return false;
+        }
+
+        ident_pat
+            .syntax()
+            .parent()
+            .and_then(|parent| {
+                // `IdentPat` can live under `RecordPat` directly under `RecordPatField` or
+                // `RecordPatFieldList`. `RecordPatField` also lives under `RecordPatFieldList`,
+                // so this tries to lookup the `IdentPat` anywhere along that structure to the
+                // `RecordPat` so we can get the containing type.
+                let record_pat = ast::RecordPatField::cast(parent.clone())
+                    .and_then(|record_pat| record_pat.syntax().parent())
+                    .or_else(|| Some(parent.clone()))
+                    .and_then(|parent| {
+                        ast::RecordPatFieldList::cast(parent)?
+                            .syntax()
+                            .parent()
+                            .and_then(ast::RecordPat::cast)
+                    });
+
+                // If this doesn't match a `RecordPat`, fallback to a `LetStmt` to see if
+                // this is initialized from a `FieldExpr`.
+                if let Some(record_pat) = record_pat {
+                    self.type_of_pat(&ast::Pat::RecordPat(record_pat))
+                } else if let Some(let_stmt) = ast::LetStmt::cast(parent) {
+                    let field_expr = match let_stmt.initializer()? {
+                        ast::Expr::FieldExpr(field_expr) => field_expr,
+                        _ => return None,
+                    };
+
+                    self.type_of_expr(&field_expr.expr()?)
+                } else {
+                    None
+                }
+            })
+            // Binding a reference to a packed type is possibly unsafe.
+            .map(|ty| ty.original.is_packed(self.db))
+            .unwrap_or(false)
+    }
+}
+
+fn macro_call_to_macro_id(
+    ctx: &mut SourceToDefCtx<'_, '_>,
+    db: &dyn AstDatabase,
+    macro_call_id: MacroCallId,
+) -> Option<MacroId> {
+    let loc = db.lookup_intern_macro_call(macro_call_id);
+    match loc.def.kind {
+        hir_expand::MacroDefKind::Declarative(it)
+        | hir_expand::MacroDefKind::BuiltIn(_, it)
+        | hir_expand::MacroDefKind::BuiltInAttr(_, it)
+        | hir_expand::MacroDefKind::BuiltInDerive(_, it)
+        | hir_expand::MacroDefKind::BuiltInEager(_, it) => {
+            ctx.macro_to_def(InFile::new(it.file_id, it.to_node(db)))
+        }
+        hir_expand::MacroDefKind::ProcMacro(_, _, it) => {
+            ctx.proc_macro_to_def(InFile::new(it.file_id, it.to_node(db)))
+        }
+    }
+}
+
+pub trait ToDef: AstNode + Clone {
+    type Def;
+
+    fn to_def(sema: &SemanticsImpl<'_>, src: InFile<Self>) -> Option<Self::Def>;
+}
+
+macro_rules! to_def_impls {
+    ($(($def:path, $ast:path, $meth:ident)),* ,) => {$(
+        impl ToDef for $ast {
+            type Def = $def;
+            fn to_def(sema: &SemanticsImpl<'_>, src: InFile<Self>) -> Option<Self::Def> {
+                sema.with_ctx(|ctx| ctx.$meth(src)).map(<$def>::from)
+            }
+        }
+    )*}
+}
+
+to_def_impls![
+    (crate::Module, ast::Module, module_to_def),
+    (crate::Module, ast::SourceFile, source_file_to_def),
+    (crate::Struct, ast::Struct, struct_to_def),
+    (crate::Enum, ast::Enum, enum_to_def),
+    (crate::Union, ast::Union, union_to_def),
+    (crate::Trait, ast::Trait, trait_to_def),
+    (crate::Impl, ast::Impl, impl_to_def),
+    (crate::TypeAlias, ast::TypeAlias, type_alias_to_def),
+    (crate::Const, ast::Const, const_to_def),
+    (crate::Static, ast::Static, static_to_def),
+    (crate::Function, ast::Fn, fn_to_def),
+    (crate::Field, ast::RecordField, record_field_to_def),
+    (crate::Field, ast::TupleField, tuple_field_to_def),
+    (crate::Variant, ast::Variant, enum_variant_to_def),
+    (crate::TypeParam, ast::TypeParam, type_param_to_def),
+    (crate::LifetimeParam, ast::LifetimeParam, lifetime_param_to_def),
+    (crate::ConstParam, ast::ConstParam, const_param_to_def),
+    (crate::GenericParam, ast::GenericParam, generic_param_to_def),
+    (crate::Macro, ast::Macro, macro_to_def),
+    (crate::Local, ast::IdentPat, bind_pat_to_def),
+    (crate::Local, ast::SelfParam, self_param_to_def),
+    (crate::Label, ast::Label, label_to_def),
+    (crate::Adt, ast::Adt, adt_to_def),
+];
+
+fn find_root(node: &SyntaxNode) -> SyntaxNode {
+    node.ancestors().last().unwrap()
+}
+
+/// `SemanticScope` encapsulates the notion of a scope (the set of visible
+/// names) at a particular program point.
+///
+/// It is a bit tricky, as scopes do not really exist inside the compiler.
+/// Rather, the compiler directly computes for each reference the definition it
+/// refers to. It might transiently compute the explicit scope map while doing
+/// so, but, generally, this is not something left after the analysis.
+///
+/// However, we do very much need explicit scopes for IDE purposes --
+/// completion, at its core, lists the contents of the current scope. The notion
+/// of scope is also useful to answer questions like "what would be the meaning
+/// of this piece of code if we inserted it into this position?".
+///
+/// So `SemanticsScope` is constructed from a specific program point (a syntax
+/// node or just a raw offset) and provides access to the set of visible names
+/// on a somewhat best-effort basis.
+///
+/// Note that if you are wondering "what does this specific existing name mean?",
+/// you'd better use the `resolve_` family of methods.
+#[derive(Debug)]
+pub struct SemanticsScope<'a> {
+    pub db: &'a dyn HirDatabase,
+    file_id: HirFileId,
+    resolver: Resolver,
+}
+
+impl<'a> SemanticsScope<'a> {
+    pub fn module(&self) -> Module {
+        Module { id: self.resolver.module() }
+    }
+
+    pub fn krate(&self) -> Crate {
+        Crate { id: self.resolver.krate() }
+    }
+
+    pub(crate) fn resolver(&self) -> &Resolver {
+        &self.resolver
+    }
+
+    /// Note: `VisibleTraits` should be treated as an opaque type, passed into `Type
+    pub fn visible_traits(&self) -> VisibleTraits {
+        let resolver = &self.resolver;
+        VisibleTraits(resolver.traits_in_scope(self.db.upcast()))
+    }
+
+    pub fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
+        let scope = self.resolver.names_in_scope(self.db.upcast());
+        for (name, entries) in scope {
+            for entry in entries {
+                let def = match entry {
+                    resolver::ScopeDef::ModuleDef(it) => ScopeDef::ModuleDef(it.into()),
+                    resolver::ScopeDef::Unknown => ScopeDef::Unknown,
+                    resolver::ScopeDef::ImplSelfType(it) => ScopeDef::ImplSelfType(it.into()),
+                    resolver::ScopeDef::AdtSelfType(it) => ScopeDef::AdtSelfType(it.into()),
+                    resolver::ScopeDef::GenericParam(id) => ScopeDef::GenericParam(id.into()),
+                    resolver::ScopeDef::Local(pat_id) => match self.resolver.body_owner() {
+                        Some(parent) => ScopeDef::Local(Local { parent, pat_id }),
+                        None => continue,
+                    },
+                    resolver::ScopeDef::Label(label_id) => match self.resolver.body_owner() {
+                        Some(parent) => ScopeDef::Label(Label { parent, label_id }),
+                        None => continue,
+                    },
+                };
+                f(name.clone(), def)
+            }
+        }
+    }
+
+    /// Resolve a path as-if it was written at the given scope. This is
+    /// necessary a heuristic, as it doesn't take hygiene into account.
+    pub fn speculative_resolve(&self, path: &ast::Path) -> Option<PathResolution> {
+        let ctx = body::LowerCtx::new(self.db.upcast(), self.file_id);
+        let path = Path::from_src(path.clone(), &ctx)?;
+        resolve_hir_path(self.db, &self.resolver, &path)
+    }
+
+    /// Iterates over associated types that may be specified after the given path (using
+    /// `Ty::Assoc` syntax).
+    pub fn assoc_type_shorthand_candidates<R>(
+        &self,
+        resolution: &PathResolution,
+        mut cb: impl FnMut(&Name, TypeAlias) -> Option<R>,
+    ) -> Option<R> {
+        let def = self.resolver.generic_def()?;
+        hir_ty::associated_type_shorthand_candidates(
+            self.db,
+            def,
+            resolution.in_type_ns()?,
+            |name, _, id| cb(name, id.into()),
+        )
+    }
+}
+
+pub struct VisibleTraits(pub FxHashSet<TraitId>);
+
+impl ops::Deref for VisibleTraits {
+    type Target = FxHashSet<TraitId>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/semantics/source_to_def.rs b/src/tools/rust-analyzer/crates/hir/src/semantics/source_to_def.rs
new file mode 100644
index 000000000..ba9a1cfb6
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/semantics/source_to_def.rs
@@ -0,0 +1,473 @@
+//! Maps *syntax* of various definitions to their semantic ids.
+//!
+//! This is a very interesting module, and, in some sense, can be considered the
+//! heart of the IDE parts of rust-analyzer.
+//!
+//! This module solves the following problem:
+//!
+//!     Given a piece of syntax, find the corresponding semantic definition (def).
+//!
+//! This problem is a part of more-or-less every IDE feature implemented. Every
+//! IDE functionality (like goto to definition), conceptually starts with a
+//! specific cursor position in a file. Starting with this text offset, we first
+//! figure out what syntactic construct are we at: is this a pattern, an
+//! expression, an item definition.
+//!
+//! Knowing only the syntax gives us relatively little info. For example,
+//! looking at the syntax of the function we can realise that it is a part of an
+//! `impl` block, but we won't be able to tell what trait function the current
+//! function overrides, and whether it does that correctly. For that, we need to
+//! go from [`ast::Fn`] to [`crate::Function`], and that's exactly what this
+//! module does.
+//!
+//! As syntax trees are values and don't know their place of origin/identity,
+//! this module also requires [`InFile`] wrappers to understand which specific
+//! real or macro-expanded file the tree comes from.
+//!
+//! The actual algorithm to resolve syntax to def is curious in two aspects:
+//!
+//!     * It is recursive
+//!     * It uses the inverse algorithm (what is the syntax for this def?)
+//!
+//! Specifically, the algorithm goes like this:
+//!
+//!     1. Find the syntactic container for the syntax. For example, field's
+//!        container is the struct, and structs container is a module.
+//!     2. Recursively get the def corresponding to container.
+//!     3. Ask the container def for all child defs. These child defs contain
+//!        the answer and answer's siblings.
+//!     4. For each child def, ask for it's source.
+//!     5. The child def whose source is the syntax node we've started with
+//!        is the answer.
+//!
+//! It's interesting that both Roslyn and Kotlin contain very similar code
+//! shape.
+//!
+//! Let's take a look at Roslyn:
+//!
+//!   <https://github.com/dotnet/roslyn/blob/36a0c338d6621cc5fe34b79d414074a95a6a489c/src/Compilers/CSharp/Portable/Compilation/SyntaxTreeSemanticModel.cs#L1403-L1429>
+//!   <https://sourceroslyn.io/#Microsoft.CodeAnalysis.CSharp/Compilation/SyntaxTreeSemanticModel.cs,1403>
+//!
+//! The `GetDeclaredType` takes `Syntax` as input, and returns `Symbol` as
+//! output. First, it retrieves a `Symbol` for parent `Syntax`:
+//!
+//! * <https://sourceroslyn.io/#Microsoft.CodeAnalysis.CSharp/Compilation/SyntaxTreeSemanticModel.cs,1423>
+//!
+//! Then, it iterates parent symbol's children, looking for one which has the
+//! same text span as the original node:
+//!
+//!   <https://sourceroslyn.io/#Microsoft.CodeAnalysis.CSharp/Compilation/SyntaxTreeSemanticModel.cs,1786>
+//!
+//! Now, let's look at Kotlin:
+//!
+//!   <https://github.com/JetBrains/kotlin/blob/a288b8b00e4754a1872b164999c6d3f3b8c8994a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/FirModuleResolveStateImpl.kt#L93-L125>
+//!
+//! This function starts with a syntax node (`KtExpression` is syntax, like all
+//! `Kt` nodes), and returns a def. It uses
+//! `getNonLocalContainingOrThisDeclaration` to get syntactic container for a
+//! current node. Then, `findSourceNonLocalFirDeclaration` gets `Fir` for this
+//! parent. Finally, `findElementIn` function traverses `Fir` children to find
+//! one with the same source we originally started with.
+//!
+//! One question is left though -- where does the recursion stops? This happens
+//! when we get to the file syntax node, which doesn't have a syntactic parent.
+//! In that case, we loop through all the crates that might contain this file
+//! and look for a module whose source is the given file.
+//!
+//! Note that the logic in this module is somewhat fundamentally imprecise --
+//! due to conditional compilation and `#[path]` attributes, there's no
+//! injective mapping from syntax nodes to defs. This is not an edge case --
+//! more or less every item in a `lib.rs` is a part of two distinct crates: a
+//! library with `--cfg test` and a library without.
+//!
+//! At the moment, we don't really handle this well and return the first answer
+//! that works. Ideally, we should first let the caller to pick a specific
+//! active crate for a given position, and then provide an API to resolve all
+//! syntax nodes against this specific crate.
+
+use base_db::FileId;
+use hir_def::{
+    attr::AttrId,
+    child_by_source::ChildBySource,
+    dyn_map::DynMap,
+    expr::{LabelId, PatId},
+    keys::{self, Key},
+    AdtId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId, FieldId, FunctionId,
+    GenericDefId, GenericParamId, ImplId, LifetimeParamId, MacroId, ModuleId, StaticId, StructId,
+    TraitId, TypeAliasId, TypeParamId, UnionId, VariantId,
+};
+use hir_expand::{name::AsName, HirFileId, MacroCallId};
+use rustc_hash::FxHashMap;
+use smallvec::SmallVec;
+use stdx::impl_from;
+use syntax::{
+    ast::{self, HasName},
+    AstNode, SyntaxNode,
+};
+
+use crate::{db::HirDatabase, InFile};
+
+pub(super) type SourceToDefCache = FxHashMap<(ChildContainer, HirFileId), DynMap>;
+
+pub(super) struct SourceToDefCtx<'a, 'b> {
+    pub(super) db: &'b dyn HirDatabase,
+    pub(super) cache: &'a mut SourceToDefCache,
+}
+
+impl SourceToDefCtx<'_, '_> {
+    pub(super) fn file_to_def(&mut self, file: FileId) -> SmallVec<[ModuleId; 1]> {
+        let _p = profile::span("SourceBinder::to_module_def");
+        let mut mods = SmallVec::new();
+        for &crate_id in self.db.relevant_crates(file).iter() {
+            // FIXME: inner items
+            let crate_def_map = self.db.crate_def_map(crate_id);
+            mods.extend(
+                crate_def_map
+                    .modules_for_file(file)
+                    .map(|local_id| crate_def_map.module_id(local_id)),
+            )
+        }
+        mods
+    }
+
+    pub(super) fn module_to_def(&mut self, src: InFile<ast::Module>) -> Option<ModuleId> {
+        let _p = profile::span("module_to_def");
+        let parent_declaration = src
+            .syntax()
+            .ancestors_with_macros_skip_attr_item(self.db.upcast())
+            .find_map(|it| it.map(ast::Module::cast).transpose());
+
+        let parent_module = match parent_declaration {
+            Some(parent_declaration) => self.module_to_def(parent_declaration),
+            None => {
+                let file_id = src.file_id.original_file(self.db.upcast());
+                self.file_to_def(file_id).get(0).copied()
+            }
+        }?;
+
+        let child_name = src.value.name()?.as_name();
+        let def_map = parent_module.def_map(self.db.upcast());
+        let &child_id = def_map[parent_module.local_id].children.get(&child_name)?;
+        Some(def_map.module_id(child_id))
+    }
+
+    pub(super) fn source_file_to_def(&mut self, src: InFile<ast::SourceFile>) -> Option<ModuleId> {
+        let _p = profile::span("source_file_to_def");
+        let file_id = src.file_id.original_file(self.db.upcast());
+        self.file_to_def(file_id).get(0).copied()
+    }
+
+    pub(super) fn trait_to_def(&mut self, src: InFile<ast::Trait>) -> Option<TraitId> {
+        self.to_def(src, keys::TRAIT)
+    }
+    pub(super) fn impl_to_def(&mut self, src: InFile<ast::Impl>) -> Option<ImplId> {
+        self.to_def(src, keys::IMPL)
+    }
+    pub(super) fn fn_to_def(&mut self, src: InFile<ast::Fn>) -> Option<FunctionId> {
+        self.to_def(src, keys::FUNCTION)
+    }
+    pub(super) fn struct_to_def(&mut self, src: InFile<ast::Struct>) -> Option<StructId> {
+        self.to_def(src, keys::STRUCT)
+    }
+    pub(super) fn enum_to_def(&mut self, src: InFile<ast::Enum>) -> Option<EnumId> {
+        self.to_def(src, keys::ENUM)
+    }
+    pub(super) fn union_to_def(&mut self, src: InFile<ast::Union>) -> Option<UnionId> {
+        self.to_def(src, keys::UNION)
+    }
+    pub(super) fn static_to_def(&mut self, src: InFile<ast::Static>) -> Option<StaticId> {
+        self.to_def(src, keys::STATIC)
+    }
+    pub(super) fn const_to_def(&mut self, src: InFile<ast::Const>) -> Option<ConstId> {
+        self.to_def(src, keys::CONST)
+    }
+    pub(super) fn type_alias_to_def(&mut self, src: InFile<ast::TypeAlias>) -> Option<TypeAliasId> {
+        self.to_def(src, keys::TYPE_ALIAS)
+    }
+    pub(super) fn record_field_to_def(&mut self, src: InFile<ast::RecordField>) -> Option<FieldId> {
+        self.to_def(src, keys::RECORD_FIELD)
+    }
+    pub(super) fn tuple_field_to_def(&mut self, src: InFile<ast::TupleField>) -> Option<FieldId> {
+        self.to_def(src, keys::TUPLE_FIELD)
+    }
+    pub(super) fn enum_variant_to_def(
+        &mut self,
+        src: InFile<ast::Variant>,
+    ) -> Option<EnumVariantId> {
+        self.to_def(src, keys::VARIANT)
+    }
+    pub(super) fn adt_to_def(
+        &mut self,
+        InFile { file_id, value }: InFile<ast::Adt>,
+    ) -> Option<AdtId> {
+        match value {
+            ast::Adt::Enum(it) => self.enum_to_def(InFile::new(file_id, it)).map(AdtId::EnumId),
+            ast::Adt::Struct(it) => {
+                self.struct_to_def(InFile::new(file_id, it)).map(AdtId::StructId)
+            }
+            ast::Adt::Union(it) => self.union_to_def(InFile::new(file_id, it)).map(AdtId::UnionId),
+        }
+    }
+    pub(super) fn bind_pat_to_def(
+        &mut self,
+        src: InFile<ast::IdentPat>,
+    ) -> Option<(DefWithBodyId, PatId)> {
+        let container = self.find_pat_or_label_container(src.syntax())?;
+        let (body, source_map) = self.db.body_with_source_map(container);
+        let src = src.map(ast::Pat::from);
+        let pat_id = source_map.node_pat(src.as_ref())?;
+        // the pattern could resolve to a constant, verify that that is not the case
+        if let crate::Pat::Bind { .. } = body[pat_id] {
+            Some((container, pat_id))
+        } else {
+            None
+        }
+    }
+    pub(super) fn self_param_to_def(
+        &mut self,
+        src: InFile<ast::SelfParam>,
+    ) -> Option<(DefWithBodyId, PatId)> {
+        let container = self.find_pat_or_label_container(src.syntax())?;
+        let (_body, source_map) = self.db.body_with_source_map(container);
+        let pat_id = source_map.node_self_param(src.as_ref())?;
+        Some((container, pat_id))
+    }
+    pub(super) fn label_to_def(
+        &mut self,
+        src: InFile<ast::Label>,
+    ) -> Option<(DefWithBodyId, LabelId)> {
+        let container = self.find_pat_or_label_container(src.syntax())?;
+        let (_body, source_map) = self.db.body_with_source_map(container);
+        let label_id = source_map.node_label(src.as_ref())?;
+        Some((container, label_id))
+    }
+
+    pub(super) fn item_to_macro_call(&mut self, src: InFile<ast::Item>) -> Option<MacroCallId> {
+        let map = self.dyn_map(src.as_ref())?;
+        map[keys::ATTR_MACRO_CALL].get(&src.value).copied()
+    }
+
+    /// (AttrId, derive attribute call id, derive call ids)
+    pub(super) fn attr_to_derive_macro_call(
+        &mut self,
+        item: InFile<&ast::Adt>,
+        src: InFile<ast::Attr>,
+    ) -> Option<(AttrId, MacroCallId, &[Option<MacroCallId>])> {
+        let map = self.dyn_map(item)?;
+        map[keys::DERIVE_MACRO_CALL]
+            .get(&src.value)
+            .map(|&(attr_id, call_id, ref ids)| (attr_id, call_id, &**ids))
+    }
+
+    pub(super) fn has_derives(&mut self, adt: InFile<&ast::Adt>) -> bool {
+        self.dyn_map(adt).as_ref().map_or(false, |map| !map[keys::DERIVE_MACRO_CALL].is_empty())
+    }
+
+    fn to_def<Ast: AstNode + 'static, ID: Copy + 'static>(
+        &mut self,
+        src: InFile<Ast>,
+        key: Key<Ast, ID>,
+    ) -> Option<ID> {
+        self.dyn_map(src.as_ref())?[key].get(&src.value).copied()
+    }
+
+    fn dyn_map<Ast: AstNode + 'static>(&mut self, src: InFile<&Ast>) -> Option<&DynMap> {
+        let container = self.find_container(src.map(|it| it.syntax()))?;
+        Some(self.cache_for(container, src.file_id))
+    }
+
+    fn cache_for(&mut self, container: ChildContainer, file_id: HirFileId) -> &DynMap {
+        let db = self.db;
+        self.cache
+            .entry((container, file_id))
+            .or_insert_with(|| container.child_by_source(db, file_id))
+    }
+
+    pub(super) fn type_param_to_def(&mut self, src: InFile<ast::TypeParam>) -> Option<TypeParamId> {
+        let container: ChildContainer = self.find_generic_param_container(src.syntax())?.into();
+        let dyn_map = self.cache_for(container, src.file_id);
+        dyn_map[keys::TYPE_PARAM].get(&src.value).copied().map(|x| TypeParamId::from_unchecked(x))
+    }
+
+    pub(super) fn lifetime_param_to_def(
+        &mut self,
+        src: InFile<ast::LifetimeParam>,
+    ) -> Option<LifetimeParamId> {
+        let container: ChildContainer = self.find_generic_param_container(src.syntax())?.into();
+        let dyn_map = self.cache_for(container, src.file_id);
+        dyn_map[keys::LIFETIME_PARAM].get(&src.value).copied()
+    }
+
+    pub(super) fn const_param_to_def(
+        &mut self,
+        src: InFile<ast::ConstParam>,
+    ) -> Option<ConstParamId> {
+        let container: ChildContainer = self.find_generic_param_container(src.syntax())?.into();
+        let dyn_map = self.cache_for(container, src.file_id);
+        dyn_map[keys::CONST_PARAM].get(&src.value).copied().map(|x| ConstParamId::from_unchecked(x))
+    }
+
+    pub(super) fn generic_param_to_def(
+        &mut self,
+        InFile { file_id, value }: InFile<ast::GenericParam>,
+    ) -> Option<GenericParamId> {
+        match value {
+            ast::GenericParam::ConstParam(it) => {
+                self.const_param_to_def(InFile::new(file_id, it)).map(GenericParamId::ConstParamId)
+            }
+            ast::GenericParam::LifetimeParam(it) => self
+                .lifetime_param_to_def(InFile::new(file_id, it))
+                .map(GenericParamId::LifetimeParamId),
+            ast::GenericParam::TypeParam(it) => {
+                self.type_param_to_def(InFile::new(file_id, it)).map(GenericParamId::TypeParamId)
+            }
+        }
+    }
+
+    pub(super) fn macro_to_def(&mut self, src: InFile<ast::Macro>) -> Option<MacroId> {
+        self.dyn_map(src.as_ref()).and_then(|it| match &src.value {
+            ast::Macro::MacroRules(value) => {
+                it[keys::MACRO_RULES].get(value).copied().map(MacroId::from)
+            }
+            ast::Macro::MacroDef(value) => it[keys::MACRO2].get(value).copied().map(MacroId::from),
+        })
+    }
+
+    pub(super) fn proc_macro_to_def(&mut self, src: InFile<ast::Fn>) -> Option<MacroId> {
+        self.dyn_map(src.as_ref())
+            .and_then(|it| it[keys::PROC_MACRO].get(&src.value).copied().map(MacroId::from))
+    }
+
+    pub(super) fn find_container(&mut self, src: InFile<&SyntaxNode>) -> Option<ChildContainer> {
+        for container in src.ancestors_with_macros_skip_attr_item(self.db.upcast()) {
+            if let Some(res) = self.container_to_def(container) {
+                return Some(res);
+            }
+        }
+
+        let def = self.file_to_def(src.file_id.original_file(self.db.upcast())).get(0).copied()?;
+        Some(def.into())
+    }
+
+    fn container_to_def(&mut self, container: InFile<SyntaxNode>) -> Option<ChildContainer> {
+        let cont = if let Some(item) = ast::Item::cast(container.value.clone()) {
+            match item {
+                ast::Item::Module(it) => self.module_to_def(container.with_value(it))?.into(),
+                ast::Item::Trait(it) => self.trait_to_def(container.with_value(it))?.into(),
+                ast::Item::Impl(it) => self.impl_to_def(container.with_value(it))?.into(),
+                ast::Item::Enum(it) => self.enum_to_def(container.with_value(it))?.into(),
+                ast::Item::TypeAlias(it) => {
+                    self.type_alias_to_def(container.with_value(it))?.into()
+                }
+                ast::Item::Struct(it) => {
+                    let def = self.struct_to_def(container.with_value(it))?;
+                    VariantId::from(def).into()
+                }
+                ast::Item::Union(it) => {
+                    let def = self.union_to_def(container.with_value(it))?;
+                    VariantId::from(def).into()
+                }
+                ast::Item::Fn(it) => {
+                    let def = self.fn_to_def(container.with_value(it))?;
+                    DefWithBodyId::from(def).into()
+                }
+                ast::Item::Static(it) => {
+                    let def = self.static_to_def(container.with_value(it))?;
+                    DefWithBodyId::from(def).into()
+                }
+                ast::Item::Const(it) => {
+                    let def = self.const_to_def(container.with_value(it))?;
+                    DefWithBodyId::from(def).into()
+                }
+                _ => return None,
+            }
+        } else {
+            let it = ast::Variant::cast(container.value)?;
+            let def = self.enum_variant_to_def(InFile::new(container.file_id, it))?;
+            VariantId::from(def).into()
+        };
+        Some(cont)
+    }
+
+    fn find_generic_param_container(&mut self, src: InFile<&SyntaxNode>) -> Option<GenericDefId> {
+        let ancestors = src.ancestors_with_macros_skip_attr_item(self.db.upcast());
+        for InFile { file_id, value } in ancestors {
+            let item = match ast::Item::cast(value) {
+                Some(it) => it,
+                None => continue,
+            };
+            let res: GenericDefId = match item {
+                ast::Item::Fn(it) => self.fn_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::Struct(it) => self.struct_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::Enum(it) => self.enum_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::Trait(it) => self.trait_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::TypeAlias(it) => {
+                    self.type_alias_to_def(InFile::new(file_id, it))?.into()
+                }
+                ast::Item::Impl(it) => self.impl_to_def(InFile::new(file_id, it))?.into(),
+                _ => continue,
+            };
+            return Some(res);
+        }
+        None
+    }
+
+    fn find_pat_or_label_container(&mut self, src: InFile<&SyntaxNode>) -> Option<DefWithBodyId> {
+        let ancestors = src.ancestors_with_macros_skip_attr_item(self.db.upcast());
+        for InFile { file_id, value } in ancestors {
+            let item = match ast::Item::cast(value) {
+                Some(it) => it,
+                None => continue,
+            };
+            let res: DefWithBodyId = match item {
+                ast::Item::Const(it) => self.const_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::Static(it) => self.static_to_def(InFile::new(file_id, it))?.into(),
+                ast::Item::Fn(it) => self.fn_to_def(InFile::new(file_id, it))?.into(),
+                _ => continue,
+            };
+            return Some(res);
+        }
+        None
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
+pub(crate) enum ChildContainer {
+    DefWithBodyId(DefWithBodyId),
+    ModuleId(ModuleId),
+    TraitId(TraitId),
+    ImplId(ImplId),
+    EnumId(EnumId),
+    VariantId(VariantId),
+    TypeAliasId(TypeAliasId),
+    /// XXX: this might be the same def as, for example an `EnumId`. However,
+    /// here the children are generic parameters, and not, eg enum variants.
+    GenericDefId(GenericDefId),
+}
+impl_from! {
+    DefWithBodyId,
+    ModuleId,
+    TraitId,
+    ImplId,
+    EnumId,
+    VariantId,
+    TypeAliasId,
+    GenericDefId
+    for ChildContainer
+}
+
+impl ChildContainer {
+    fn child_by_source(self, db: &dyn HirDatabase, file_id: HirFileId) -> DynMap {
+        let db = db.upcast();
+        match self {
+            ChildContainer::DefWithBodyId(it) => it.child_by_source(db, file_id),
+            ChildContainer::ModuleId(it) => it.child_by_source(db, file_id),
+            ChildContainer::TraitId(it) => it.child_by_source(db, file_id),
+            ChildContainer::ImplId(it) => it.child_by_source(db, file_id),
+            ChildContainer::EnumId(it) => it.child_by_source(db, file_id),
+            ChildContainer::VariantId(it) => it.child_by_source(db, file_id),
+            ChildContainer::TypeAliasId(_) => DynMap::default(),
+            ChildContainer::GenericDefId(it) => it.child_by_source(db, file_id),
+        }
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs b/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs
new file mode 100644
index 000000000..1eb51b20c
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs
@@ -0,0 +1,915 @@
+//! Lookup hir elements using positions in the source code. This is a lossy
+//! transformation: in general, a single source might correspond to several
+//! modules, functions, etc, due to macros, cfgs and `#[path=]` attributes on
+//! modules.
+//!
+//! So, this modules should not be used during hir construction, it exists
+//! purely for "IDE needs".
+use std::{
+    iter::{self, once},
+    sync::Arc,
+};
+
+use hir_def::{
+    body::{
+        self,
+        scope::{ExprScopes, ScopeId},
+        Body, BodySourceMap,
+    },
+    expr::{ExprId, Pat, PatId},
+    macro_id_to_def_id,
+    path::{ModPath, Path, PathKind},
+    resolver::{resolver_for_scope, Resolver, TypeNs, ValueNs},
+    type_ref::Mutability,
+    AsMacroCall, AssocItemId, DefWithBodyId, FieldId, FunctionId, ItemContainerId, LocalFieldId,
+    Lookup, ModuleDefId, VariantId,
+};
+use hir_expand::{
+    builtin_fn_macro::BuiltinFnLikeExpander, hygiene::Hygiene, name::AsName, HirFileId, InFile,
+};
+use hir_ty::{
+    diagnostics::{
+        record_literal_missing_fields, record_pattern_missing_fields, unsafe_expressions,
+        UnsafeExpr,
+    },
+    method_resolution, Adjust, Adjustment, AutoBorrow, InferenceResult, Interner, Substitution,
+    TyExt, TyKind, TyLoweringContext,
+};
+use itertools::Itertools;
+use smallvec::SmallVec;
+use syntax::{
+    ast::{self, AstNode},
+    SyntaxKind, SyntaxNode, TextRange, TextSize,
+};
+
+use crate::{
+    db::HirDatabase, semantics::PathResolution, Adt, AssocItem, BindingMode, BuiltinAttr,
+    BuiltinType, Callable, Const, DeriveHelper, Field, Function, Local, Macro, ModuleDef, Static,
+    Struct, ToolModule, Trait, Type, TypeAlias, Variant,
+};
+
+/// `SourceAnalyzer` is a convenience wrapper which exposes HIR API in terms of
+/// original source files. It should not be used inside the HIR itself.
+#[derive(Debug)]
+pub(crate) struct SourceAnalyzer {
+    pub(crate) file_id: HirFileId,
+    pub(crate) resolver: Resolver,
+    def: Option<(DefWithBodyId, Arc<Body>, Arc<BodySourceMap>)>,
+    infer: Option<Arc<InferenceResult>>,
+}
+
+impl SourceAnalyzer {
+    pub(crate) fn new_for_body(
+        db: &dyn HirDatabase,
+        def: DefWithBodyId,
+        node @ InFile { file_id, .. }: InFile<&SyntaxNode>,
+        offset: Option<TextSize>,
+    ) -> SourceAnalyzer {
+        let (body, source_map) = db.body_with_source_map(def);
+        let scopes = db.expr_scopes(def);
+        let scope = match offset {
+            None => scope_for(&scopes, &source_map, node),
+            Some(offset) => scope_for_offset(db, &scopes, &source_map, node.file_id, offset),
+        };
+        let resolver = resolver_for_scope(db.upcast(), def, scope);
+        SourceAnalyzer {
+            resolver,
+            def: Some((def, body, source_map)),
+            infer: Some(db.infer(def)),
+            file_id,
+        }
+    }
+
+    pub(crate) fn new_for_body_no_infer(
+        db: &dyn HirDatabase,
+        def: DefWithBodyId,
+        node @ InFile { file_id, .. }: InFile<&SyntaxNode>,
+        offset: Option<TextSize>,
+    ) -> SourceAnalyzer {
+        let (body, source_map) = db.body_with_source_map(def);
+        let scopes = db.expr_scopes(def);
+        let scope = match offset {
+            None => scope_for(&scopes, &source_map, node),
+            Some(offset) => scope_for_offset(db, &scopes, &source_map, node.file_id, offset),
+        };
+        let resolver = resolver_for_scope(db.upcast(), def, scope);
+        SourceAnalyzer { resolver, def: Some((def, body, source_map)), infer: None, file_id }
+    }
+
+    pub(crate) fn new_for_resolver(
+        resolver: Resolver,
+        node: InFile<&SyntaxNode>,
+    ) -> SourceAnalyzer {
+        SourceAnalyzer { resolver, def: None, infer: None, file_id: node.file_id }
+    }
+
+    fn body_source_map(&self) -> Option<&BodySourceMap> {
+        self.def.as_ref().map(|(.., source_map)| &**source_map)
+    }
+    fn body(&self) -> Option<&Body> {
+        self.def.as_ref().map(|(_, body, _)| &**body)
+    }
+
+    fn expr_id(&self, db: &dyn HirDatabase, expr: &ast::Expr) -> Option<ExprId> {
+        let src = match expr {
+            ast::Expr::MacroExpr(expr) => {
+                self.expand_expr(db, InFile::new(self.file_id, expr.macro_call()?.clone()))?
+            }
+            _ => InFile::new(self.file_id, expr.clone()),
+        };
+        let sm = self.body_source_map()?;
+        sm.node_expr(src.as_ref())
+    }
+
+    fn pat_id(&self, pat: &ast::Pat) -> Option<PatId> {
+        // FIXME: macros, see `expr_id`
+        let src = InFile { file_id: self.file_id, value: pat };
+        self.body_source_map()?.node_pat(src)
+    }
+
+    fn expand_expr(
+        &self,
+        db: &dyn HirDatabase,
+        expr: InFile<ast::MacroCall>,
+    ) -> Option<InFile<ast::Expr>> {
+        let macro_file = self.body_source_map()?.node_macro_file(expr.as_ref())?;
+        let expanded = db.parse_or_expand(macro_file)?;
+
+        let res = match ast::MacroCall::cast(expanded.clone()) {
+            Some(call) => self.expand_expr(db, InFile::new(macro_file, call))?,
+            _ => InFile::new(macro_file, ast::Expr::cast(expanded)?),
+        };
+        Some(res)
+    }
+
+    pub(crate) fn is_implicit_reborrow(
+        &self,
+        db: &dyn HirDatabase,
+        expr: &ast::Expr,
+    ) -> Option<Mutability> {
+        let expr_id = self.expr_id(db, expr)?;
+        let infer = self.infer.as_ref()?;
+        let adjustments = infer.expr_adjustments.get(&expr_id)?;
+        adjustments.windows(2).find_map(|slice| match slice {
+            &[Adjustment {kind: Adjust::Deref(None), ..}, Adjustment {kind: Adjust::Borrow(AutoBorrow::Ref(m)), ..}] => Some(match m {
+                hir_ty::Mutability::Mut => Mutability::Mut,
+                hir_ty::Mutability::Not => Mutability::Shared,
+            }),
+            _ => None,
+        })
+    }
+
+    pub(crate) fn type_of_expr(
+        &self,
+        db: &dyn HirDatabase,
+        expr: &ast::Expr,
+    ) -> Option<(Type, Option<Type>)> {
+        let expr_id = self.expr_id(db, expr)?;
+        let infer = self.infer.as_ref()?;
+        let coerced = infer
+            .expr_adjustments
+            .get(&expr_id)
+            .and_then(|adjusts| adjusts.last().map(|adjust| adjust.target.clone()));
+        let ty = infer[expr_id].clone();
+        let mk_ty = |ty| Type::new_with_resolver(db, &self.resolver, ty);
+        Some((mk_ty(ty), coerced.map(mk_ty)))
+    }
+
+    pub(crate) fn type_of_pat(
+        &self,
+        db: &dyn HirDatabase,
+        pat: &ast::Pat,
+    ) -> Option<(Type, Option<Type>)> {
+        let pat_id = self.pat_id(pat)?;
+        let infer = self.infer.as_ref()?;
+        let coerced = infer
+            .pat_adjustments
+            .get(&pat_id)
+            .and_then(|adjusts| adjusts.last().map(|adjust| adjust.clone()));
+        let ty = infer[pat_id].clone();
+        let mk_ty = |ty| Type::new_with_resolver(db, &self.resolver, ty);
+        Some((mk_ty(ty), coerced.map(mk_ty)))
+    }
+
+    pub(crate) fn type_of_self(
+        &self,
+        db: &dyn HirDatabase,
+        param: &ast::SelfParam,
+    ) -> Option<Type> {
+        let src = InFile { file_id: self.file_id, value: param };
+        let pat_id = self.body_source_map()?.node_self_param(src)?;
+        let ty = self.infer.as_ref()?[pat_id].clone();
+        Some(Type::new_with_resolver(db, &self.resolver, ty))
+    }
+
+    pub(crate) fn binding_mode_of_pat(
+        &self,
+        _db: &dyn HirDatabase,
+        pat: &ast::IdentPat,
+    ) -> Option<BindingMode> {
+        let pat_id = self.pat_id(&pat.clone().into())?;
+        let infer = self.infer.as_ref()?;
+        infer.pat_binding_modes.get(&pat_id).map(|bm| match bm {
+            hir_ty::BindingMode::Move => BindingMode::Move,
+            hir_ty::BindingMode::Ref(hir_ty::Mutability::Mut) => BindingMode::Ref(Mutability::Mut),
+            hir_ty::BindingMode::Ref(hir_ty::Mutability::Not) => {
+                BindingMode::Ref(Mutability::Shared)
+            }
+        })
+    }
+    pub(crate) fn pattern_adjustments(
+        &self,
+        db: &dyn HirDatabase,
+        pat: &ast::Pat,
+    ) -> Option<SmallVec<[Type; 1]>> {
+        let pat_id = self.pat_id(&pat)?;
+        let infer = self.infer.as_ref()?;
+        Some(
+            infer
+                .pat_adjustments
+                .get(&pat_id)?
+                .iter()
+                .map(|ty| Type::new_with_resolver(db, &self.resolver, ty.clone()))
+                .collect(),
+        )
+    }
+
+    pub(crate) fn resolve_method_call_as_callable(
+        &self,
+        db: &dyn HirDatabase,
+        call: &ast::MethodCallExpr,
+    ) -> Option<Callable> {
+        let expr_id = self.expr_id(db, &call.clone().into())?;
+        let (func, substs) = self.infer.as_ref()?.method_resolution(expr_id)?;
+        let ty = db.value_ty(func.into()).substitute(Interner, &substs);
+        let ty = Type::new_with_resolver(db, &self.resolver, ty);
+        let mut res = ty.as_callable(db)?;
+        res.is_bound_method = true;
+        Some(res)
+    }
+
+    pub(crate) fn resolve_method_call(
+        &self,
+        db: &dyn HirDatabase,
+        call: &ast::MethodCallExpr,
+    ) -> Option<FunctionId> {
+        let expr_id = self.expr_id(db, &call.clone().into())?;
+        let (f_in_trait, substs) = self.infer.as_ref()?.method_resolution(expr_id)?;
+        let f_in_impl = self.resolve_impl_method(db, f_in_trait, &substs);
+        f_in_impl.or(Some(f_in_trait))
+    }
+
+    pub(crate) fn resolve_field(
+        &self,
+        db: &dyn HirDatabase,
+        field: &ast::FieldExpr,
+    ) -> Option<Field> {
+        let expr_id = self.expr_id(db, &field.clone().into())?;
+        self.infer.as_ref()?.field_resolution(expr_id).map(|it| it.into())
+    }
+
+    pub(crate) fn resolve_record_field(
+        &self,
+        db: &dyn HirDatabase,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>, Type)> {
+        let record_expr = ast::RecordExpr::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
+        let expr = ast::Expr::from(record_expr);
+        let expr_id = self.body_source_map()?.node_expr(InFile::new(self.file_id, &expr))?;
+
+        let local_name = field.field_name()?.as_name();
+        let local = if field.name_ref().is_some() {
+            None
+        } else {
+            let path = ModPath::from_segments(PathKind::Plain, once(local_name.clone()));
+            match self.resolver.resolve_path_in_value_ns_fully(db.upcast(), &path) {
+                Some(ValueNs::LocalBinding(pat_id)) => {
+                    Some(Local { pat_id, parent: self.resolver.body_owner()? })
+                }
+                _ => None,
+            }
+        };
+        let (_, subst) = self.infer.as_ref()?.type_of_expr.get(expr_id)?.as_adt()?;
+        let variant = self.infer.as_ref()?.variant_resolution_for_expr(expr_id)?;
+        let variant_data = variant.variant_data(db.upcast());
+        let field = FieldId { parent: variant, local_id: variant_data.field(&local_name)? };
+        let field_ty =
+            db.field_types(variant).get(field.local_id)?.clone().substitute(Interner, subst);
+        Some((field.into(), local, Type::new_with_resolver(db, &self.resolver, field_ty)))
+    }
+
+    pub(crate) fn resolve_record_pat_field(
+        &self,
+        db: &dyn HirDatabase,
+        field: &ast::RecordPatField,
+    ) -> Option<Field> {
+        let field_name = field.field_name()?.as_name();
+        let record_pat = ast::RecordPat::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
+        let pat_id = self.pat_id(&record_pat.into())?;
+        let variant = self.infer.as_ref()?.variant_resolution_for_pat(pat_id)?;
+        let variant_data = variant.variant_data(db.upcast());
+        let field = FieldId { parent: variant, local_id: variant_data.field(&field_name)? };
+        Some(field.into())
+    }
+
+    pub(crate) fn resolve_macro_call(
+        &self,
+        db: &dyn HirDatabase,
+        macro_call: InFile<&ast::MacroCall>,
+    ) -> Option<Macro> {
+        let ctx = body::LowerCtx::new(db.upcast(), macro_call.file_id);
+        let path = macro_call.value.path().and_then(|ast| Path::from_src(ast, &ctx))?;
+        self.resolver.resolve_path_as_macro(db.upcast(), path.mod_path()).map(|it| it.into())
+    }
+
+    pub(crate) fn resolve_bind_pat_to_const(
+        &self,
+        db: &dyn HirDatabase,
+        pat: &ast::IdentPat,
+    ) -> Option<ModuleDef> {
+        let pat_id = self.pat_id(&pat.clone().into())?;
+        let body = self.body()?;
+        let path = match &body[pat_id] {
+            Pat::Path(path) => path,
+            _ => return None,
+        };
+        let res = resolve_hir_path(db, &self.resolver, path)?;
+        match res {
+            PathResolution::Def(def) => Some(def),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn resolve_path(
+        &self,
+        db: &dyn HirDatabase,
+        path: &ast::Path,
+    ) -> Option<PathResolution> {
+        let parent = path.syntax().parent();
+        let parent = || parent.clone();
+
+        let mut prefer_value_ns = false;
+        let resolved = (|| {
+            if let Some(path_expr) = parent().and_then(ast::PathExpr::cast) {
+                let expr_id = self.expr_id(db, &path_expr.into())?;
+                let infer = self.infer.as_ref()?;
+                if let Some(assoc) = infer.assoc_resolutions_for_expr(expr_id) {
+                    let assoc = match assoc {
+                        AssocItemId::FunctionId(f_in_trait) => {
+                            match infer.type_of_expr.get(expr_id) {
+                                None => assoc,
+                                Some(func_ty) => {
+                                    if let TyKind::FnDef(_fn_def, subs) = func_ty.kind(Interner) {
+                                        self.resolve_impl_method(db, f_in_trait, subs)
+                                            .map(AssocItemId::FunctionId)
+                                            .unwrap_or(assoc)
+                                    } else {
+                                        assoc
+                                    }
+                                }
+                            }
+                        }
+
+                        _ => assoc,
+                    };
+
+                    return Some(PathResolution::Def(AssocItem::from(assoc).into()));
+                }
+                if let Some(VariantId::EnumVariantId(variant)) =
+                    infer.variant_resolution_for_expr(expr_id)
+                {
+                    return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
+                }
+                prefer_value_ns = true;
+            } else if let Some(path_pat) = parent().and_then(ast::PathPat::cast) {
+                let pat_id = self.pat_id(&path_pat.into())?;
+                if let Some(assoc) = self.infer.as_ref()?.assoc_resolutions_for_pat(pat_id) {
+                    return Some(PathResolution::Def(AssocItem::from(assoc).into()));
+                }
+                if let Some(VariantId::EnumVariantId(variant)) =
+                    self.infer.as_ref()?.variant_resolution_for_pat(pat_id)
+                {
+                    return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
+                }
+            } else if let Some(rec_lit) = parent().and_then(ast::RecordExpr::cast) {
+                let expr_id = self.expr_id(db, &rec_lit.into())?;
+                if let Some(VariantId::EnumVariantId(variant)) =
+                    self.infer.as_ref()?.variant_resolution_for_expr(expr_id)
+                {
+                    return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
+                }
+            } else {
+                let record_pat = parent().and_then(ast::RecordPat::cast).map(ast::Pat::from);
+                let tuple_struct_pat =
+                    || parent().and_then(ast::TupleStructPat::cast).map(ast::Pat::from);
+                if let Some(pat) = record_pat.or_else(tuple_struct_pat) {
+                    let pat_id = self.pat_id(&pat)?;
+                    let variant_res_for_pat =
+                        self.infer.as_ref()?.variant_resolution_for_pat(pat_id);
+                    if let Some(VariantId::EnumVariantId(variant)) = variant_res_for_pat {
+                        return Some(PathResolution::Def(ModuleDef::Variant(variant.into())));
+                    }
+                }
+            }
+            None
+        })();
+        if let Some(_) = resolved {
+            return resolved;
+        }
+
+        // This must be a normal source file rather than macro file.
+        let hygiene = Hygiene::new(db.upcast(), self.file_id);
+        let ctx = body::LowerCtx::with_hygiene(db.upcast(), &hygiene);
+        let hir_path = Path::from_src(path.clone(), &ctx)?;
+
+        // Case where path is a qualifier of a use tree, e.g. foo::bar::{Baz, Qux} where we are
+        // trying to resolve foo::bar.
+        if let Some(use_tree) = parent().and_then(ast::UseTree::cast) {
+            if use_tree.coloncolon_token().is_some() {
+                return resolve_hir_path_qualifier(db, &self.resolver, &hir_path);
+            }
+        }
+
+        let meta_path = path
+            .syntax()
+            .ancestors()
+            .take_while(|it| {
+                let kind = it.kind();
+                ast::Path::can_cast(kind) || ast::Meta::can_cast(kind)
+            })
+            .last()
+            .and_then(ast::Meta::cast);
+
+        // Case where path is a qualifier of another path, e.g. foo::bar::Baz where we are
+        // trying to resolve foo::bar.
+        if path.parent_path().is_some() {
+            return match resolve_hir_path_qualifier(db, &self.resolver, &hir_path) {
+                None if meta_path.is_some() => {
+                    path.first_segment().and_then(|it| it.name_ref()).and_then(|name_ref| {
+                        ToolModule::by_name(db, self.resolver.krate().into(), &name_ref.text())
+                            .map(PathResolution::ToolModule)
+                    })
+                }
+                res => res,
+            };
+        } else if let Some(meta_path) = meta_path {
+            // Case where we are resolving the final path segment of a path in an attribute
+            // in this case we have to check for inert/builtin attributes and tools and prioritize
+            // resolution of attributes over other namespaces
+            if let Some(name_ref) = path.as_single_name_ref() {
+                let builtin =
+                    BuiltinAttr::by_name(db, self.resolver.krate().into(), &name_ref.text());
+                if let Some(_) = builtin {
+                    return builtin.map(PathResolution::BuiltinAttr);
+                }
+
+                if let Some(attr) = meta_path.parent_attr() {
+                    let adt = if let Some(field) =
+                        attr.syntax().parent().and_then(ast::RecordField::cast)
+                    {
+                        field.syntax().ancestors().take(4).find_map(ast::Adt::cast)
+                    } else if let Some(field) =
+                        attr.syntax().parent().and_then(ast::TupleField::cast)
+                    {
+                        field.syntax().ancestors().take(4).find_map(ast::Adt::cast)
+                    } else if let Some(variant) =
+                        attr.syntax().parent().and_then(ast::Variant::cast)
+                    {
+                        variant.syntax().ancestors().nth(2).and_then(ast::Adt::cast)
+                    } else {
+                        None
+                    };
+                    if let Some(adt) = adt {
+                        let ast_id = db.ast_id_map(self.file_id).ast_id(&adt);
+                        if let Some(helpers) = self
+                            .resolver
+                            .def_map()
+                            .derive_helpers_in_scope(InFile::new(self.file_id, ast_id))
+                        {
+                            // FIXME: Multiple derives can have the same helper
+                            let name_ref = name_ref.as_name();
+                            for (macro_id, mut helpers) in
+                                helpers.iter().group_by(|(_, macro_id, ..)| macro_id).into_iter()
+                            {
+                                if let Some(idx) = helpers.position(|(name, ..)| *name == name_ref)
+                                {
+                                    return Some(PathResolution::DeriveHelper(DeriveHelper {
+                                        derive: *macro_id,
+                                        idx,
+                                    }));
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            return match resolve_hir_path_as_macro(db, &self.resolver, &hir_path) {
+                Some(m) => Some(PathResolution::Def(ModuleDef::Macro(m))),
+                // this labels any path that starts with a tool module as the tool itself, this is technically wrong
+                // but there is no benefit in differentiating these two cases for the time being
+                None => path.first_segment().and_then(|it| it.name_ref()).and_then(|name_ref| {
+                    ToolModule::by_name(db, self.resolver.krate().into(), &name_ref.text())
+                        .map(PathResolution::ToolModule)
+                }),
+            };
+        }
+        if parent().map_or(false, |it| ast::Visibility::can_cast(it.kind())) {
+            resolve_hir_path_qualifier(db, &self.resolver, &hir_path)
+        } else {
+            resolve_hir_path_(db, &self.resolver, &hir_path, prefer_value_ns)
+        }
+    }
+
+    pub(crate) fn record_literal_missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        literal: &ast::RecordExpr,
+    ) -> Option<Vec<(Field, Type)>> {
+        let body = self.body()?;
+        let infer = self.infer.as_ref()?;
+
+        let expr_id = self.expr_id(db, &literal.clone().into())?;
+        let substs = infer.type_of_expr[expr_id].as_adt()?.1;
+
+        let (variant, missing_fields, _exhaustive) =
+            record_literal_missing_fields(db, infer, expr_id, &body[expr_id])?;
+        let res = self.missing_fields(db, substs, variant, missing_fields);
+        Some(res)
+    }
+
+    pub(crate) fn record_pattern_missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        pattern: &ast::RecordPat,
+    ) -> Option<Vec<(Field, Type)>> {
+        let body = self.body()?;
+        let infer = self.infer.as_ref()?;
+
+        let pat_id = self.pat_id(&pattern.clone().into())?;
+        let substs = infer.type_of_pat[pat_id].as_adt()?.1;
+
+        let (variant, missing_fields, _exhaustive) =
+            record_pattern_missing_fields(db, infer, pat_id, &body[pat_id])?;
+        let res = self.missing_fields(db, substs, variant, missing_fields);
+        Some(res)
+    }
+
+    fn missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        substs: &Substitution,
+        variant: VariantId,
+        missing_fields: Vec<LocalFieldId>,
+    ) -> Vec<(Field, Type)> {
+        let field_types = db.field_types(variant);
+
+        missing_fields
+            .into_iter()
+            .map(|local_id| {
+                let field = FieldId { parent: variant, local_id };
+                let ty = field_types[local_id].clone().substitute(Interner, substs);
+                (field.into(), Type::new_with_resolver_inner(db, &self.resolver, ty))
+            })
+            .collect()
+    }
+
+    pub(crate) fn expand(
+        &self,
+        db: &dyn HirDatabase,
+        macro_call: InFile<&ast::MacroCall>,
+    ) -> Option<HirFileId> {
+        let krate = self.resolver.krate();
+        let macro_call_id = macro_call.as_call_id(db.upcast(), krate, |path| {
+            self.resolver
+                .resolve_path_as_macro(db.upcast(), &path)
+                .map(|it| macro_id_to_def_id(db.upcast(), it))
+        })?;
+        Some(macro_call_id.as_file()).filter(|it| it.expansion_level(db.upcast()) < 64)
+    }
+
+    pub(crate) fn resolve_variant(
+        &self,
+        db: &dyn HirDatabase,
+        record_lit: ast::RecordExpr,
+    ) -> Option<VariantId> {
+        let infer = self.infer.as_ref()?;
+        let expr_id = self.expr_id(db, &record_lit.into())?;
+        infer.variant_resolution_for_expr(expr_id)
+    }
+
+    pub(crate) fn is_unsafe_macro_call(
+        &self,
+        db: &dyn HirDatabase,
+        macro_call: InFile<&ast::MacroCall>,
+    ) -> bool {
+        // check for asm/global_asm
+        if let Some(mac) = self.resolve_macro_call(db, macro_call) {
+            let ex = match mac.id {
+                hir_def::MacroId::Macro2Id(it) => it.lookup(db.upcast()).expander,
+                hir_def::MacroId::MacroRulesId(it) => it.lookup(db.upcast()).expander,
+                _ => hir_def::MacroExpander::Declarative,
+            };
+            match ex {
+                hir_def::MacroExpander::BuiltIn(e)
+                    if e == BuiltinFnLikeExpander::Asm || e == BuiltinFnLikeExpander::GlobalAsm =>
+                {
+                    return true
+                }
+                _ => (),
+            }
+        }
+        let macro_expr = match macro_call
+            .map(|it| it.syntax().parent().and_then(ast::MacroExpr::cast))
+            .transpose()
+        {
+            Some(it) => it,
+            None => return false,
+        };
+
+        if let (Some((def, body, sm)), Some(infer)) = (&self.def, &self.infer) {
+            if let Some(expanded_expr) = sm.macro_expansion_expr(macro_expr.as_ref()) {
+                let mut is_unsafe = false;
+                unsafe_expressions(
+                    db,
+                    infer,
+                    *def,
+                    body,
+                    expanded_expr,
+                    &mut |UnsafeExpr { inside_unsafe_block, .. }| is_unsafe |= !inside_unsafe_block,
+                );
+                return is_unsafe;
+            }
+        }
+        false
+    }
+
+    fn resolve_impl_method(
+        &self,
+        db: &dyn HirDatabase,
+        func: FunctionId,
+        substs: &Substitution,
+    ) -> Option<FunctionId> {
+        let impled_trait = match func.lookup(db.upcast()).container {
+            ItemContainerId::TraitId(trait_id) => trait_id,
+            _ => return None,
+        };
+        if substs.is_empty(Interner) {
+            return None;
+        }
+        let self_ty = substs.at(Interner, 0).ty(Interner)?;
+        let krate = self.resolver.krate();
+        let trait_env = self.resolver.body_owner()?.as_generic_def_id().map_or_else(
+            || Arc::new(hir_ty::TraitEnvironment::empty(krate)),
+            |d| db.trait_environment(d),
+        );
+
+        let fun_data = db.function_data(func);
+        method_resolution::lookup_impl_method(self_ty, db, trait_env, impled_trait, &fun_data.name)
+    }
+}
+
+fn scope_for(
+    scopes: &ExprScopes,
+    source_map: &BodySourceMap,
+    node: InFile<&SyntaxNode>,
+) -> Option<ScopeId> {
+    node.value
+        .ancestors()
+        .filter_map(ast::Expr::cast)
+        .filter_map(|it| source_map.node_expr(InFile::new(node.file_id, &it)))
+        .find_map(|it| scopes.scope_for(it))
+}
+
+fn scope_for_offset(
+    db: &dyn HirDatabase,
+    scopes: &ExprScopes,
+    source_map: &BodySourceMap,
+    from_file: HirFileId,
+    offset: TextSize,
+) -> Option<ScopeId> {
+    scopes
+        .scope_by_expr()
+        .iter()
+        .filter_map(|(id, scope)| {
+            let InFile { file_id, value } = source_map.expr_syntax(*id).ok()?;
+            if from_file == file_id {
+                return Some((value.text_range(), scope));
+            }
+
+            // FIXME handle attribute expansion
+            let source = iter::successors(file_id.call_node(db.upcast()), |it| {
+                it.file_id.call_node(db.upcast())
+            })
+            .find(|it| it.file_id == from_file)
+            .filter(|it| it.value.kind() == SyntaxKind::MACRO_CALL)?;
+            Some((source.value.text_range(), scope))
+        })
+        .filter(|(expr_range, _scope)| expr_range.start() <= offset && offset <= expr_range.end())
+        // find containing scope
+        .min_by_key(|(expr_range, _scope)| expr_range.len())
+        .map(|(expr_range, scope)| {
+            adjust(db, scopes, source_map, expr_range, from_file, offset).unwrap_or(*scope)
+        })
+}
+
+// XXX: during completion, cursor might be outside of any particular
+// expression. Try to figure out the correct scope...
+fn adjust(
+    db: &dyn HirDatabase,
+    scopes: &ExprScopes,
+    source_map: &BodySourceMap,
+    expr_range: TextRange,
+    from_file: HirFileId,
+    offset: TextSize,
+) -> Option<ScopeId> {
+    let child_scopes = scopes
+        .scope_by_expr()
+        .iter()
+        .filter_map(|(id, scope)| {
+            let source = source_map.expr_syntax(*id).ok()?;
+            // FIXME: correctly handle macro expansion
+            if source.file_id != from_file {
+                return None;
+            }
+            let root = source.file_syntax(db.upcast());
+            let node = source.value.to_node(&root);
+            Some((node.syntax().text_range(), scope))
+        })
+        .filter(|&(range, _)| {
+            range.start() <= offset && expr_range.contains_range(range) && range != expr_range
+        });
+
+    child_scopes
+        .max_by(|&(r1, _), &(r2, _)| {
+            if r1.contains_range(r2) {
+                std::cmp::Ordering::Greater
+            } else if r2.contains_range(r1) {
+                std::cmp::Ordering::Less
+            } else {
+                r1.start().cmp(&r2.start())
+            }
+        })
+        .map(|(_ptr, scope)| *scope)
+}
+
+#[inline]
+pub(crate) fn resolve_hir_path(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    path: &Path,
+) -> Option<PathResolution> {
+    resolve_hir_path_(db, resolver, path, false)
+}
+
+#[inline]
+pub(crate) fn resolve_hir_path_as_macro(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    path: &Path,
+) -> Option<Macro> {
+    resolver.resolve_path_as_macro(db.upcast(), path.mod_path()).map(Into::into)
+}
+
+fn resolve_hir_path_(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    path: &Path,
+    prefer_value_ns: bool,
+) -> Option<PathResolution> {
+    let types = || {
+        let (ty, unresolved) = match path.type_anchor() {
+            Some(type_ref) => {
+                let (_, res) = TyLoweringContext::new(db, resolver).lower_ty_ext(type_ref);
+                res.map(|ty_ns| (ty_ns, path.segments().first()))
+            }
+            None => {
+                let (ty, remaining) =
+                    resolver.resolve_path_in_type_ns(db.upcast(), path.mod_path())?;
+                match remaining {
+                    Some(remaining) if remaining > 1 => {
+                        if remaining + 1 == path.segments().len() {
+                            Some((ty, path.segments().last()))
+                        } else {
+                            None
+                        }
+                    }
+                    _ => Some((ty, path.segments().get(1))),
+                }
+            }
+        }?;
+
+        // If we are in a TypeNs for a Trait, and we have an unresolved name, try to resolve it as a type
+        // within the trait's associated types.
+        if let (Some(unresolved), &TypeNs::TraitId(trait_id)) = (&unresolved, &ty) {
+            if let Some(type_alias_id) =
+                db.trait_data(trait_id).associated_type_by_name(unresolved.name)
+            {
+                return Some(PathResolution::Def(ModuleDefId::from(type_alias_id).into()));
+            }
+        }
+
+        let res = match ty {
+            TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
+            TypeNs::GenericParam(id) => PathResolution::TypeParam(id.into()),
+            TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => {
+                PathResolution::Def(Adt::from(it).into())
+            }
+            TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
+            TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
+            TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
+            TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
+        };
+        match unresolved {
+            Some(unresolved) => resolver
+                .generic_def()
+                .and_then(|def| {
+                    hir_ty::associated_type_shorthand_candidates(
+                        db,
+                        def,
+                        res.in_type_ns()?,
+                        |name, _, id| (name == unresolved.name).then(|| id),
+                    )
+                })
+                .map(TypeAlias::from)
+                .map(Into::into)
+                .map(PathResolution::Def),
+            None => Some(res),
+        }
+    };
+
+    let body_owner = resolver.body_owner();
+    let values = || {
+        resolver.resolve_path_in_value_ns_fully(db.upcast(), path.mod_path()).and_then(|val| {
+            let res = match val {
+                ValueNs::LocalBinding(pat_id) => {
+                    let var = Local { parent: body_owner?, pat_id };
+                    PathResolution::Local(var)
+                }
+                ValueNs::FunctionId(it) => PathResolution::Def(Function::from(it).into()),
+                ValueNs::ConstId(it) => PathResolution::Def(Const::from(it).into()),
+                ValueNs::StaticId(it) => PathResolution::Def(Static::from(it).into()),
+                ValueNs::StructId(it) => PathResolution::Def(Struct::from(it).into()),
+                ValueNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
+                ValueNs::ImplSelf(impl_id) => PathResolution::SelfType(impl_id.into()),
+                ValueNs::GenericParam(id) => PathResolution::ConstParam(id.into()),
+            };
+            Some(res)
+        })
+    };
+
+    let items = || {
+        resolver
+            .resolve_module_path_in_items(db.upcast(), path.mod_path())
+            .take_types()
+            .map(|it| PathResolution::Def(it.into()))
+    };
+
+    let macros = || {
+        resolver
+            .resolve_path_as_macro(db.upcast(), path.mod_path())
+            .map(|def| PathResolution::Def(ModuleDef::Macro(def.into())))
+    };
+
+    if prefer_value_ns { values().or_else(types) } else { types().or_else(values) }
+        .or_else(items)
+        .or_else(macros)
+}
+
+/// Resolves a path where we know it is a qualifier of another path.
+///
+/// For example, if we have:
+/// ```
+/// mod my {
+///     pub mod foo {
+///         struct Bar;
+///     }
+///
+///     pub fn foo() {}
+/// }
+/// ```
+/// then we know that `foo` in `my::foo::Bar` refers to the module, not the function.
+fn resolve_hir_path_qualifier(
+    db: &dyn HirDatabase,
+    resolver: &Resolver,
+    path: &Path,
+) -> Option<PathResolution> {
+    resolver
+        .resolve_path_in_type_ns_fully(db.upcast(), path.mod_path())
+        .map(|ty| match ty {
+            TypeNs::SelfType(it) => PathResolution::SelfType(it.into()),
+            TypeNs::GenericParam(id) => PathResolution::TypeParam(id.into()),
+            TypeNs::AdtSelfType(it) | TypeNs::AdtId(it) => {
+                PathResolution::Def(Adt::from(it).into())
+            }
+            TypeNs::EnumVariantId(it) => PathResolution::Def(Variant::from(it).into()),
+            TypeNs::TypeAliasId(it) => PathResolution::Def(TypeAlias::from(it).into()),
+            TypeNs::BuiltinType(it) => PathResolution::Def(BuiltinType::from(it).into()),
+            TypeNs::TraitId(it) => PathResolution::Def(Trait::from(it).into()),
+        })
+        .or_else(|| {
+            resolver
+                .resolve_module_path_in_items(db.upcast(), path.mod_path())
+                .take_types()
+                .map(|it| PathResolution::Def(it.into()))
+        })
+}
diff --git a/src/tools/rust-analyzer/crates/hir/src/symbols.rs b/src/tools/rust-analyzer/crates/hir/src/symbols.rs
new file mode 100644
index 000000000..616a406c7
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir/src/symbols.rs
@@ -0,0 +1,348 @@
+//! File symbol extraction.
+
+use base_db::FileRange;
+use hir_def::{
+    item_tree::ItemTreeNode, src::HasSource, AdtId, AssocItemId, AssocItemLoc, DefWithBodyId,
+    HasModule, ImplId, ItemContainerId, Lookup, MacroId, ModuleDefId, ModuleId, TraitId,
+};
+use hir_expand::{HirFileId, InFile};
+use hir_ty::db::HirDatabase;
+use syntax::{ast::HasName, AstNode, SmolStr, SyntaxNode, SyntaxNodePtr};
+
+use crate::{Module, Semantics};
+
+/// The actual data that is stored in the index. It should be as compact as
+/// possible.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FileSymbol {
+    pub name: SmolStr,
+    pub loc: DeclarationLocation,
+    pub kind: FileSymbolKind,
+    pub container_name: Option<SmolStr>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct DeclarationLocation {
+    /// The file id for both the `ptr` and `name_ptr`.
+    pub hir_file_id: HirFileId,
+    /// This points to the whole syntax node of the declaration.
+    pub ptr: SyntaxNodePtr,
+    /// This points to the [`syntax::ast::Name`] identifier of the declaration.
+    pub name_ptr: SyntaxNodePtr,
+}
+
+impl DeclarationLocation {
+    pub fn syntax<DB: HirDatabase>(&self, sema: &Semantics<'_, DB>) -> Option<SyntaxNode> {
+        let root = sema.parse_or_expand(self.hir_file_id)?;
+        Some(self.ptr.to_node(&root))
+    }
+
+    pub fn original_range(&self, db: &dyn HirDatabase) -> Option<FileRange> {
+        let node = resolve_node(db, self.hir_file_id, &self.ptr)?;
+        Some(node.as_ref().original_file_range(db.upcast()))
+    }
+
+    pub fn original_name_range(&self, db: &dyn HirDatabase) -> Option<FileRange> {
+        let node = resolve_node(db, self.hir_file_id, &self.name_ptr)?;
+        node.as_ref().original_file_range_opt(db.upcast())
+    }
+}
+
+fn resolve_node(
+    db: &dyn HirDatabase,
+    file_id: HirFileId,
+    ptr: &SyntaxNodePtr,
+) -> Option<InFile<SyntaxNode>> {
+    let root = db.parse_or_expand(file_id)?;
+    let node = ptr.to_node(&root);
+    Some(InFile::new(file_id, node))
+}
+
+#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
+pub enum FileSymbolKind {
+    Const,
+    Enum,
+    Function,
+    Macro,
+    Module,
+    Static,
+    Struct,
+    Trait,
+    TypeAlias,
+    Union,
+}
+
+impl FileSymbolKind {
+    pub fn is_type(self: FileSymbolKind) -> bool {
+        matches!(
+            self,
+            FileSymbolKind::Struct
+                | FileSymbolKind::Enum
+                | FileSymbolKind::Trait
+                | FileSymbolKind::TypeAlias
+                | FileSymbolKind::Union
+        )
+    }
+}
+
+/// Represents an outstanding module that the symbol collector must collect symbols from.
+struct SymbolCollectorWork {
+    module_id: ModuleId,
+    parent: Option<DefWithBodyId>,
+}
+
+pub struct SymbolCollector<'a> {
+    db: &'a dyn HirDatabase,
+    symbols: Vec<FileSymbol>,
+    work: Vec<SymbolCollectorWork>,
+    current_container_name: Option<SmolStr>,
+}
+
+/// Given a [`ModuleId`] and a [`HirDatabase`], use the DefMap for the module's crate to collect
+/// all symbols that should be indexed for the given module.
+impl<'a> SymbolCollector<'a> {
+    pub fn collect(db: &dyn HirDatabase, module: Module) -> Vec<FileSymbol> {
+        let mut symbol_collector = SymbolCollector {
+            db,
+            symbols: Default::default(),
+            current_container_name: None,
+            // The initial work is the root module we're collecting, additional work will
+            // be populated as we traverse the module's definitions.
+            work: vec![SymbolCollectorWork { module_id: module.into(), parent: None }],
+        };
+
+        while let Some(work) = symbol_collector.work.pop() {
+            symbol_collector.do_work(work);
+        }
+
+        symbol_collector.symbols
+    }
+
+    fn do_work(&mut self, work: SymbolCollectorWork) {
+        self.db.unwind_if_cancelled();
+
+        let parent_name = work.parent.and_then(|id| self.def_with_body_id_name(id));
+        self.with_container_name(parent_name, |s| s.collect_from_module(work.module_id));
+    }
+
+    fn collect_from_module(&mut self, module_id: ModuleId) {
+        let def_map = module_id.def_map(self.db.upcast());
+        let scope = &def_map[module_id.local_id].scope;
+
+        for module_def_id in scope.declarations() {
+            match module_def_id {
+                ModuleDefId::ModuleId(id) => self.push_module(id),
+                ModuleDefId::FunctionId(id) => {
+                    self.push_decl_assoc(id, FileSymbolKind::Function);
+                    self.collect_from_body(id);
+                }
+                ModuleDefId::AdtId(AdtId::StructId(id)) => {
+                    self.push_decl(id, FileSymbolKind::Struct)
+                }
+                ModuleDefId::AdtId(AdtId::EnumId(id)) => self.push_decl(id, FileSymbolKind::Enum),
+                ModuleDefId::AdtId(AdtId::UnionId(id)) => self.push_decl(id, FileSymbolKind::Union),
+                ModuleDefId::ConstId(id) => {
+                    self.push_decl_assoc(id, FileSymbolKind::Const);
+                    self.collect_from_body(id);
+                }
+                ModuleDefId::StaticId(id) => {
+                    self.push_decl_assoc(id, FileSymbolKind::Static);
+                    self.collect_from_body(id);
+                }
+                ModuleDefId::TraitId(id) => {
+                    self.push_decl(id, FileSymbolKind::Trait);
+                    self.collect_from_trait(id);
+                }
+                ModuleDefId::TypeAliasId(id) => {
+                    self.push_decl_assoc(id, FileSymbolKind::TypeAlias);
+                }
+                ModuleDefId::MacroId(id) => match id {
+                    MacroId::Macro2Id(id) => self.push_decl(id, FileSymbolKind::Macro),
+                    MacroId::MacroRulesId(id) => self.push_decl(id, FileSymbolKind::Macro),
+                    MacroId::ProcMacroId(id) => self.push_decl(id, FileSymbolKind::Macro),
+                },
+                // Don't index these.
+                ModuleDefId::BuiltinType(_) => {}
+                ModuleDefId::EnumVariantId(_) => {}
+            }
+        }
+
+        for impl_id in scope.impls() {
+            self.collect_from_impl(impl_id);
+        }
+
+        for const_id in scope.unnamed_consts() {
+            self.collect_from_body(const_id);
+        }
+
+        for (_, id) in scope.legacy_macros() {
+            for &id in id {
+                if id.module(self.db.upcast()) == module_id {
+                    match id {
+                        MacroId::Macro2Id(id) => self.push_decl(id, FileSymbolKind::Macro),
+                        MacroId::MacroRulesId(id) => self.push_decl(id, FileSymbolKind::Macro),
+                        MacroId::ProcMacroId(id) => self.push_decl(id, FileSymbolKind::Macro),
+                    }
+                }
+            }
+        }
+    }
+
+    fn collect_from_body(&mut self, body_id: impl Into<DefWithBodyId>) {
+        let body_id = body_id.into();
+        let body = self.db.body(body_id);
+
+        // Descend into the blocks and enqueue collection of all modules within.
+        for (_, def_map) in body.blocks(self.db.upcast()) {
+            for (id, _) in def_map.modules() {
+                self.work.push(SymbolCollectorWork {
+                    module_id: def_map.module_id(id),
+                    parent: Some(body_id),
+                });
+            }
+        }
+    }
+
+    fn collect_from_impl(&mut self, impl_id: ImplId) {
+        let impl_data = self.db.impl_data(impl_id);
+        for &assoc_item_id in &impl_data.items {
+            self.push_assoc_item(assoc_item_id)
+        }
+    }
+
+    fn collect_from_trait(&mut self, trait_id: TraitId) {
+        let trait_data = self.db.trait_data(trait_id);
+        self.with_container_name(trait_data.name.as_text(), |s| {
+            for &(_, assoc_item_id) in &trait_data.items {
+                s.push_assoc_item(assoc_item_id);
+            }
+        });
+    }
+
+    fn with_container_name(&mut self, container_name: Option<SmolStr>, f: impl FnOnce(&mut Self)) {
+        if let Some(container_name) = container_name {
+            let prev = self.current_container_name.replace(container_name);
+            f(self);
+            self.current_container_name = prev;
+        } else {
+            f(self);
+        }
+    }
+
+    fn current_container_name(&self) -> Option<SmolStr> {
+        self.current_container_name.clone()
+    }
+
+    fn def_with_body_id_name(&self, body_id: DefWithBodyId) -> Option<SmolStr> {
+        match body_id {
+            DefWithBodyId::FunctionId(id) => Some(
+                id.lookup(self.db.upcast()).source(self.db.upcast()).value.name()?.text().into(),
+            ),
+            DefWithBodyId::StaticId(id) => Some(
+                id.lookup(self.db.upcast()).source(self.db.upcast()).value.name()?.text().into(),
+            ),
+            DefWithBodyId::ConstId(id) => Some(
+                id.lookup(self.db.upcast()).source(self.db.upcast()).value.name()?.text().into(),
+            ),
+        }
+    }
+
+    fn push_assoc_item(&mut self, assoc_item_id: AssocItemId) {
+        match assoc_item_id {
+            AssocItemId::FunctionId(id) => self.push_decl_assoc(id, FileSymbolKind::Function),
+            AssocItemId::ConstId(id) => self.push_decl_assoc(id, FileSymbolKind::Const),
+            AssocItemId::TypeAliasId(id) => self.push_decl_assoc(id, FileSymbolKind::TypeAlias),
+        }
+    }
+
+    fn push_decl_assoc<L, T>(&mut self, id: L, kind: FileSymbolKind)
+    where
+        L: Lookup<Data = AssocItemLoc<T>>,
+        T: ItemTreeNode,
+        <T as ItemTreeNode>::Source: HasName,
+    {
+        fn container_name(db: &dyn HirDatabase, container: ItemContainerId) -> Option<SmolStr> {
+            match container {
+                ItemContainerId::ModuleId(module_id) => {
+                    let module = Module::from(module_id);
+                    module.name(db).and_then(|name| name.as_text())
+                }
+                ItemContainerId::TraitId(trait_id) => {
+                    let trait_data = db.trait_data(trait_id);
+                    trait_data.name.as_text()
+                }
+                ItemContainerId::ImplId(_) | ItemContainerId::ExternBlockId(_) => None,
+            }
+        }
+
+        self.push_file_symbol(|s| {
+            let loc = id.lookup(s.db.upcast());
+            let source = loc.source(s.db.upcast());
+            let name_node = source.value.name()?;
+            let container_name =
+                container_name(s.db, loc.container).or_else(|| s.current_container_name());
+
+            Some(FileSymbol {
+                name: name_node.text().into(),
+                kind,
+                container_name,
+                loc: DeclarationLocation {
+                    hir_file_id: source.file_id,
+                    ptr: SyntaxNodePtr::new(source.value.syntax()),
+                    name_ptr: SyntaxNodePtr::new(name_node.syntax()),
+                },
+            })
+        })
+    }
+
+    fn push_decl<L>(&mut self, id: L, kind: FileSymbolKind)
+    where
+        L: Lookup,
+        <L as Lookup>::Data: HasSource,
+        <<L as Lookup>::Data as HasSource>::Value: HasName,
+    {
+        self.push_file_symbol(|s| {
+            let loc = id.lookup(s.db.upcast());
+            let source = loc.source(s.db.upcast());
+            let name_node = source.value.name()?;
+
+            Some(FileSymbol {
+                name: name_node.text().into(),
+                kind,
+                container_name: s.current_container_name(),
+                loc: DeclarationLocation {
+                    hir_file_id: source.file_id,
+                    ptr: SyntaxNodePtr::new(source.value.syntax()),
+                    name_ptr: SyntaxNodePtr::new(name_node.syntax()),
+                },
+            })
+        })
+    }
+
+    fn push_module(&mut self, module_id: ModuleId) {
+        self.push_file_symbol(|s| {
+            let def_map = module_id.def_map(s.db.upcast());
+            let module_data = &def_map[module_id.local_id];
+            let declaration = module_data.origin.declaration()?;
+            let module = declaration.to_node(s.db.upcast());
+            let name_node = module.name()?;
+
+            Some(FileSymbol {
+                name: name_node.text().into(),
+                kind: FileSymbolKind::Module,
+                container_name: s.current_container_name(),
+                loc: DeclarationLocation {
+                    hir_file_id: declaration.file_id,
+                    ptr: SyntaxNodePtr::new(module.syntax()),
+                    name_ptr: SyntaxNodePtr::new(name_node.syntax()),
+                },
+            })
+        })
+    }
+
+    fn push_file_symbol(&mut self, f: impl FnOnce(&Self) -> Option<FileSymbol>) {
+        if let Some(file_symbol) = f(self) {
+            self.symbols.push(file_symbol);
+        }
+    }
+}