9 files changed, 4365 insertions, 0 deletions

diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
new file mode 100644
index 000000000..3e99c8773
--- /dev/null
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -0,0 +1,1279 @@
+//! The core of the module-level name resolution algorithm.
+//!
+//! `DefCollector::collect` contains the fixed-point iteration loop which
+//! resolves imports and expands macros.
+
+use base_db::{CrateId, FileId, ProcMacroId};
+use cfg::CfgOptions;
+use hir_expand::{
+    ast_id_map::FileAstId,
+    builtin_derive::find_builtin_derive,
+    builtin_macro::find_builtin_macro,
+    name::{name, AsName, Name},
+    proc_macro::ProcMacroExpander,
+    HirFileId, MacroCallId, MacroDefId, MacroDefKind,
+};
+use rustc_hash::FxHashMap;
+use syntax::ast;
+use test_utils::mark;
+
+use crate::{
+    attr::Attrs,
+    db::DefDatabase,
+    item_scope::{ImportType, PerNsGlobImports},
+    item_tree::{
+        self, FileItemTreeId, ItemTree, ItemTreeId, MacroCall, Mod, ModItem, ModKind, StructDefKind,
+    },
+    nameres::{
+        diagnostics::DefDiagnostic, mod_resolution::ModDir, path_resolution::ReachedFixedPoint,
+        BuiltinShadowMode, CrateDefMap, ModuleData, ModuleOrigin, ResolveMode,
+    },
+    path::{ImportAlias, ModPath, PathKind},
+    per_ns::PerNs,
+    visibility::{RawVisibility, Visibility},
+    AdtId, AsMacroCall, AstId, AstIdWithPath, ConstLoc, ContainerId, EnumLoc, EnumVariantId,
+    FunctionLoc, ImplLoc, Intern, LocalModuleId, ModuleDefId, ModuleId, StaticLoc, StructLoc,
+    TraitLoc, TypeAliasLoc, UnionLoc,
+};
+
+const GLOB_RECURSION_LIMIT: usize = 100;
+const EXPANSION_DEPTH_LIMIT: usize = 128;
+const FIXED_POINT_LIMIT: usize = 8192;
+
+pub(super) fn collect_defs(db: &dyn DefDatabase, mut def_map: CrateDefMap) -> CrateDefMap {
+    let crate_graph = db.crate_graph();
+
+    // populate external prelude
+    for dep in &crate_graph[def_map.krate].dependencies {
+        log::debug!("crate dep {:?} -> {:?}", dep.name, dep.crate_id);
+        let dep_def_map = db.crate_def_map(dep.crate_id);
+        def_map.extern_prelude.insert(
+            dep.as_name(),
+            ModuleId { krate: dep.crate_id, local_id: dep_def_map.root }.into(),
+        );
+
+        // look for the prelude
+        // If the dependency defines a prelude, we overwrite an already defined
+        // prelude. This is necessary to import the "std" prelude if a crate
+        // depends on both "core" and "std".
+        if dep_def_map.prelude.is_some() {
+            def_map.prelude = dep_def_map.prelude;
+        }
+    }
+
+    let cfg_options = &crate_graph[def_map.krate].cfg_options;
+    let proc_macros = &crate_graph[def_map.krate].proc_macro;
+    let proc_macros = proc_macros
+        .iter()
+        .enumerate()
+        .map(|(idx, it)| {
+            // FIXME: a hacky way to create a Name from string.
+            let name = tt::Ident { text: it.name.clone(), id: tt::TokenId::unspecified() };
+            (name.as_name(), ProcMacroExpander::new(def_map.krate, ProcMacroId(idx as u32)))
+        })
+        .collect();
+
+    let mut collector = DefCollector {
+        db,
+        def_map,
+        glob_imports: FxHashMap::default(),
+        unresolved_imports: Vec::new(),
+        resolved_imports: Vec::new(),
+
+        unexpanded_macros: Vec::new(),
+        unexpanded_attribute_macros: Vec::new(),
+        mod_dirs: FxHashMap::default(),
+        cfg_options,
+        proc_macros,
+        from_glob_import: Default::default(),
+    };
+    collector.collect();
+    collector.finish()
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+enum PartialResolvedImport {
+    /// None of any namespaces is resolved
+    Unresolved,
+    /// One of namespaces is resolved
+    Indeterminate(PerNs),
+    /// All namespaces are resolved, OR it is came from other crate
+    Resolved(PerNs),
+}
+
+impl PartialResolvedImport {
+    fn namespaces(&self) -> PerNs {
+        match self {
+            PartialResolvedImport::Unresolved => PerNs::none(),
+            PartialResolvedImport::Indeterminate(ns) => *ns,
+            PartialResolvedImport::Resolved(ns) => *ns,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct Import {
+    pub path: ModPath,
+    pub alias: Option<ImportAlias>,
+    pub visibility: RawVisibility,
+    pub is_glob: bool,
+    pub is_prelude: bool,
+    pub is_extern_crate: bool,
+    pub is_macro_use: bool,
+}
+
+impl Import {
+    fn from_use(tree: &ItemTree, id: FileItemTreeId<item_tree::Import>) -> Self {
+        let it = &tree[id];
+        let visibility = &tree[it.visibility];
+        Self {
+            path: it.path.clone(),
+            alias: it.alias.clone(),
+            visibility: visibility.clone(),
+            is_glob: it.is_glob,
+            is_prelude: it.is_prelude,
+            is_extern_crate: false,
+            is_macro_use: false,
+        }
+    }
+
+    fn from_extern_crate(tree: &ItemTree, id: FileItemTreeId<item_tree::ExternCrate>) -> Self {
+        let it = &tree[id];
+        let visibility = &tree[it.visibility];
+        Self {
+            path: it.path.clone(),
+            alias: it.alias.clone(),
+            visibility: visibility.clone(),
+            is_glob: false,
+            is_prelude: false,
+            is_extern_crate: true,
+            is_macro_use: it.is_macro_use,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct ImportDirective {
+    module_id: LocalModuleId,
+    import: Import,
+    status: PartialResolvedImport,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct MacroDirective {
+    module_id: LocalModuleId,
+    ast_id: AstIdWithPath<ast::MacroCall>,
+    legacy: Option<MacroCallId>,
+    depth: usize,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct DeriveDirective {
+    module_id: LocalModuleId,
+    ast_id: AstIdWithPath<ast::Item>,
+}
+
+struct DefData<'a> {
+    id: ModuleDefId,
+    name: &'a Name,
+    visibility: &'a RawVisibility,
+    has_constructor: bool,
+}
+
+/// Walks the tree of module recursively
+struct DefCollector<'a> {
+    db: &'a dyn DefDatabase,
+    def_map: CrateDefMap,
+    glob_imports: FxHashMap<LocalModuleId, Vec<(LocalModuleId, Visibility)>>,
+    unresolved_imports: Vec<ImportDirective>,
+    resolved_imports: Vec<ImportDirective>,
+    unexpanded_macros: Vec<MacroDirective>,
+    unexpanded_attribute_macros: Vec<DeriveDirective>,
+    mod_dirs: FxHashMap<LocalModuleId, ModDir>,
+    cfg_options: &'a CfgOptions,
+    proc_macros: Vec<(Name, ProcMacroExpander)>,
+    from_glob_import: PerNsGlobImports,
+}
+
+impl DefCollector<'_> {
+    fn collect(&mut self) {
+        let file_id = self.db.crate_graph()[self.def_map.krate].root_file_id;
+        let item_tree = self.db.item_tree(file_id.into());
+        let module_id = self.def_map.root;
+        self.def_map.modules[module_id].origin = ModuleOrigin::CrateRoot { definition: file_id };
+        ModCollector {
+            def_collector: &mut *self,
+            macro_depth: 0,
+            module_id,
+            file_id: file_id.into(),
+            item_tree: &item_tree,
+            mod_dir: ModDir::root(),
+        }
+        .collect(item_tree.top_level_items());
+
+        // main name resolution fixed-point loop.
+        let mut i = 0;
+        loop {
+            self.db.check_canceled();
+            self.resolve_imports();
+
+            match self.resolve_macros() {
+                ReachedFixedPoint::Yes => break,
+                ReachedFixedPoint::No => i += 1,
+            }
+            if i == FIXED_POINT_LIMIT {
+                log::error!("name resolution is stuck");
+                break;
+            }
+        }
+
+        // Resolve all indeterminate resolved imports again
+        // As some of the macros will expand newly import shadowing partial resolved imports
+        // FIXME: We maybe could skip this, if we handle the Indetermine imports in `resolve_imports`
+        // correctly
+        let partial_resolved = self.resolved_imports.iter().filter_map(|directive| {
+            if let PartialResolvedImport::Indeterminate(_) = directive.status {
+                let mut directive = directive.clone();
+                directive.status = PartialResolvedImport::Unresolved;
+                Some(directive)
+            } else {
+                None
+            }
+        });
+        self.unresolved_imports.extend(partial_resolved);
+        self.resolve_imports();
+
+        let unresolved_imports = std::mem::replace(&mut self.unresolved_imports, Vec::new());
+        // show unresolved imports in completion, etc
+        for directive in unresolved_imports {
+            self.record_resolved_import(&directive)
+        }
+
+        // Record proc-macros
+        self.collect_proc_macro();
+    }
+
+    fn collect_proc_macro(&mut self) {
+        let proc_macros = std::mem::take(&mut self.proc_macros);
+        for (name, expander) in proc_macros {
+            let krate = self.def_map.krate;
+
+            let macro_id = MacroDefId {
+                ast_id: None,
+                krate: Some(krate),
+                kind: MacroDefKind::CustomDerive(expander),
+                local_inner: false,
+            };
+
+            self.define_proc_macro(name.clone(), macro_id);
+        }
+    }
+
+    /// Define a macro with `macro_rules`.
+    ///
+    /// It will define the macro in legacy textual scope, and if it has `#[macro_export]`,
+    /// then it is also defined in the root module scope.
+    /// You can `use` or invoke it by `crate::macro_name` anywhere, before or after the definition.
+    ///
+    /// It is surprising that the macro will never be in the current module scope.
+    /// These code fails with "unresolved import/macro",
+    /// ```rust,compile_fail
+    /// mod m { macro_rules! foo { () => {} } }
+    /// use m::foo as bar;
+    /// ```
+    ///
+    /// ```rust,compile_fail
+    /// macro_rules! foo { () => {} }
+    /// self::foo!();
+    /// crate::foo!();
+    /// ```
+    ///
+    /// Well, this code compiles, because the plain path `foo` in `use` is searched
+    /// in the legacy textual scope only.
+    /// ```rust
+    /// macro_rules! foo { () => {} }
+    /// use foo as bar;
+    /// ```
+    fn define_macro(
+        &mut self,
+        module_id: LocalModuleId,
+        name: Name,
+        macro_: MacroDefId,
+        export: bool,
+    ) {
+        // Textual scoping
+        self.define_legacy_macro(module_id, name.clone(), macro_);
+
+        // Module scoping
+        // In Rust, `#[macro_export]` macros are unconditionally visible at the
+        // crate root, even if the parent modules is **not** visible.
+        if export {
+            self.update(
+                self.def_map.root,
+                &[(Some(name), PerNs::macros(macro_, Visibility::Public))],
+                Visibility::Public,
+                ImportType::Named,
+            );
+        }
+    }
+
+    /// Define a legacy textual scoped macro in module
+    ///
+    /// We use a map `legacy_macros` to store all legacy textual scoped macros visible per module.
+    /// It will clone all macros from parent legacy scope, whose definition is prior to
+    /// the definition of current module.
+    /// And also, `macro_use` on a module will import all legacy macros visible inside to
+    /// current legacy scope, with possible shadowing.
+    fn define_legacy_macro(&mut self, module_id: LocalModuleId, name: Name, mac: MacroDefId) {
+        // Always shadowing
+        self.def_map.modules[module_id].scope.define_legacy_macro(name, mac);
+    }
+
+    /// Define a proc macro
+    ///
+    /// A proc macro is similar to normal macro scope, but it would not visiable in legacy textual scoped.
+    /// And unconditionally exported.
+    fn define_proc_macro(&mut self, name: Name, macro_: MacroDefId) {
+        self.update(
+            self.def_map.root,
+            &[(Some(name), PerNs::macros(macro_, Visibility::Public))],
+            Visibility::Public,
+            ImportType::Named,
+        );
+    }
+
+    /// Import macros from `#[macro_use] extern crate`.
+    fn import_macros_from_extern_crate(
+        &mut self,
+        current_module_id: LocalModuleId,
+        import: &item_tree::ExternCrate,
+    ) {
+        log::debug!(
+            "importing macros from extern crate: {:?} ({:?})",
+            import,
+            self.def_map.edition,
+        );
+
+        let res = self.def_map.resolve_name_in_extern_prelude(
+            &import
+                .path
+                .as_ident()
+                .expect("extern crate should have been desugared to one-element path"),
+        );
+
+        if let Some(ModuleDefId::ModuleId(m)) = res.take_types() {
+            mark::hit!(macro_rules_from_other_crates_are_visible_with_macro_use);
+            self.import_all_macros_exported(current_module_id, m.krate);
+        }
+    }
+
+    /// Import all exported macros from another crate
+    ///
+    /// Exported macros are just all macros in the root module scope.
+    /// Note that it contains not only all `#[macro_export]` macros, but also all aliases
+    /// created by `use` in the root module, ignoring the visibility of `use`.
+    fn import_all_macros_exported(&mut self, current_module_id: LocalModuleId, krate: CrateId) {
+        let def_map = self.db.crate_def_map(krate);
+        for (name, def) in def_map[def_map.root].scope.macros() {
+            // `macro_use` only bring things into legacy scope.
+            self.define_legacy_macro(current_module_id, name.clone(), def);
+        }
+    }
+
+    /// Import resolution
+    ///
+    /// This is a fix point algorithm. We resolve imports until no forward
+    /// progress in resolving imports is made
+    fn resolve_imports(&mut self) {
+        let mut n_previous_unresolved = self.unresolved_imports.len() + 1;
+
+        while self.unresolved_imports.len() < n_previous_unresolved {
+            n_previous_unresolved = self.unresolved_imports.len();
+            let imports = std::mem::replace(&mut self.unresolved_imports, Vec::new());
+            for mut directive in imports {
+                directive.status = self.resolve_import(directive.module_id, &directive.import);
+                match directive.status {
+                    PartialResolvedImport::Indeterminate(_) => {
+                        self.record_resolved_import(&directive);
+                        // FIXME: For avoid performance regression,
+                        // we consider an imported resolved if it is indeterminate (i.e not all namespace resolved)
+                        self.resolved_imports.push(directive)
+                    }
+                    PartialResolvedImport::Resolved(_) => {
+                        self.record_resolved_import(&directive);
+                        self.resolved_imports.push(directive)
+                    }
+                    PartialResolvedImport::Unresolved => {
+                        self.unresolved_imports.push(directive);
+                    }
+                }
+            }
+        }
+    }
+
+    fn resolve_import(&self, module_id: LocalModuleId, import: &Import) -> PartialResolvedImport {
+        log::debug!("resolving import: {:?} ({:?})", import, self.def_map.edition);
+        if import.is_extern_crate {
+            let res = self.def_map.resolve_name_in_extern_prelude(
+                &import
+                    .path
+                    .as_ident()
+                    .expect("extern crate should have been desugared to one-element path"),
+            );
+            PartialResolvedImport::Resolved(res)
+        } else {
+            let res = self.def_map.resolve_path_fp_with_macro(
+                self.db,
+                ResolveMode::Import,
+                module_id,
+                &import.path,
+                BuiltinShadowMode::Module,
+            );
+
+            let def = res.resolved_def;
+            if res.reached_fixedpoint == ReachedFixedPoint::No || def.is_none() {
+                return PartialResolvedImport::Unresolved;
+            }
+
+            if let Some(krate) = res.krate {
+                if krate != self.def_map.krate {
+                    return PartialResolvedImport::Resolved(def);
+                }
+            }
+
+            // Check whether all namespace is resolved
+            if def.take_types().is_some()
+                && def.take_values().is_some()
+                && def.take_macros().is_some()
+            {
+                PartialResolvedImport::Resolved(def)
+            } else {
+                PartialResolvedImport::Indeterminate(def)
+            }
+        }
+    }
+
+    fn record_resolved_import(&mut self, directive: &ImportDirective) {
+        let module_id = directive.module_id;
+        let import = &directive.import;
+        let def = directive.status.namespaces();
+        let vis = self
+            .def_map
+            .resolve_visibility(self.db, module_id, &directive.import.visibility)
+            .unwrap_or(Visibility::Public);
+
+        if import.is_glob {
+            log::debug!("glob import: {:?}", import);
+            match def.take_types() {
+                Some(ModuleDefId::ModuleId(m)) => {
+                    if import.is_prelude {
+                        mark::hit!(std_prelude);
+                        self.def_map.prelude = Some(m);
+                    } else if m.krate != self.def_map.krate {
+                        mark::hit!(glob_across_crates);
+                        // glob import from other crate => we can just import everything once
+                        let item_map = self.db.crate_def_map(m.krate);
+                        let scope = &item_map[m.local_id].scope;
+
+                        // Module scoped macros is included
+                        let items = scope
+                            .resolutions()
+                            // only keep visible names...
+                            .map(|(n, res)| {
+                                (n, res.filter_visibility(|v| v.is_visible_from_other_crate()))
+                            })
+                            .filter(|(_, res)| !res.is_none())
+                            .collect::<Vec<_>>();
+
+                        self.update(module_id, &items, vis, ImportType::Glob);
+                    } else {
+                        // glob import from same crate => we do an initial
+                        // import, and then need to propagate any further
+                        // additions
+                        let scope = &self.def_map[m.local_id].scope;
+
+                        // Module scoped macros is included
+                        let items = scope
+                            .resolutions()
+                            // only keep visible names...
+                            .map(|(n, res)| {
+                                (
+                                    n,
+                                    res.filter_visibility(|v| {
+                                        v.is_visible_from_def_map(&self.def_map, module_id)
+                                    }),
+                                )
+                            })
+                            .filter(|(_, res)| !res.is_none())
+                            .collect::<Vec<_>>();
+
+                        self.update(module_id, &items, vis, ImportType::Glob);
+                        // record the glob import in case we add further items
+                        let glob = self.glob_imports.entry(m.local_id).or_default();
+                        if !glob.iter().any(|(mid, _)| *mid == module_id) {
+                            glob.push((module_id, vis));
+                        }
+                    }
+                }
+                Some(ModuleDefId::AdtId(AdtId::EnumId(e))) => {
+                    mark::hit!(glob_enum);
+                    // glob import from enum => just import all the variants
+
+                    // XXX: urgh, so this works by accident! Here, we look at
+                    // the enum data, and, in theory, this might require us to
+                    // look back at the crate_def_map, creating a cycle. For
+                    // example, `enum E { crate::some_macro!(); }`. Luckely, the
+                    // only kind of macro that is allowed inside enum is a
+                    // `cfg_macro`, and we don't need to run name resolution for
+                    // it, but this is sheer luck!
+                    let enum_data = self.db.enum_data(e);
+                    let resolutions = enum_data
+                        .variants
+                        .iter()
+                        .map(|(local_id, variant_data)| {
+                            let name = variant_data.name.clone();
+                            let variant = EnumVariantId { parent: e, local_id };
+                            let res = PerNs::both(variant.into(), variant.into(), vis);
+                            (Some(name), res)
+                        })
+                        .collect::<Vec<_>>();
+                    self.update(module_id, &resolutions, vis, ImportType::Glob);
+                }
+                Some(d) => {
+                    log::debug!("glob import {:?} from non-module/enum {:?}", import, d);
+                }
+                None => {
+                    log::debug!("glob import {:?} didn't resolve as type", import);
+                }
+            }
+        } else {
+            match import.path.segments.last() {
+                Some(last_segment) => {
+                    let name = match &import.alias {
+                        Some(ImportAlias::Alias(name)) => Some(name.clone()),
+                        Some(ImportAlias::Underscore) => None,
+                        None => Some(last_segment.clone()),
+                    };
+                    log::debug!("resolved import {:?} ({:?}) to {:?}", name, import, def);
+
+                    // extern crates in the crate root are special-cased to insert entries into the extern prelude: rust-lang/rust#54658
+                    if import.is_extern_crate && module_id == self.def_map.root {
+                        if let (Some(def), Some(name)) = (def.take_types(), name.as_ref()) {
+                            self.def_map.extern_prelude.insert(name.clone(), def);
+                        }
+                    }
+
+                    self.update(module_id, &[(name, def)], vis, ImportType::Named);
+                }
+                None => mark::hit!(bogus_paths),
+            }
+        }
+    }
+
+    fn update(
+        &mut self,
+        module_id: LocalModuleId,
+        resolutions: &[(Option<Name>, PerNs)],
+        vis: Visibility,
+        import_type: ImportType,
+    ) {
+        self.db.check_canceled();
+        self.update_recursive(module_id, resolutions, vis, import_type, 0)
+    }
+
+    fn update_recursive(
+        &mut self,
+        module_id: LocalModuleId,
+        resolutions: &[(Option<Name>, PerNs)],
+        // All resolutions are imported with this visibility; the visibilies in
+        // the `PerNs` values are ignored and overwritten
+        vis: Visibility,
+        import_type: ImportType,
+        depth: usize,
+    ) {
+        if depth > GLOB_RECURSION_LIMIT {
+            // prevent stack overflows (but this shouldn't be possible)
+            panic!("infinite recursion in glob imports!");
+        }
+        let mut changed = false;
+
+        for (name, res) in resolutions {
+            match name {
+                Some(name) => {
+                    let scope = &mut self.def_map.modules[module_id].scope;
+                    changed |= scope.push_res_with_import(
+                        &mut self.from_glob_import,
+                        (module_id, name.clone()),
+                        res.with_visibility(vis),
+                        import_type,
+                    );
+                }
+                None => {
+                    let tr = match res.take_types() {
+                        Some(ModuleDefId::TraitId(tr)) => tr,
+                        Some(other) => {
+                            log::debug!("non-trait `_` import of {:?}", other);
+                            continue;
+                        }
+                        None => continue,
+                    };
+                    let old_vis = self.def_map.modules[module_id].scope.unnamed_trait_vis(tr);
+                    let should_update = match old_vis {
+                        None => true,
+                        Some(old_vis) => {
+                            let max_vis = old_vis.max(vis, &self.def_map).unwrap_or_else(|| {
+                                panic!("`Tr as _` imports with unrelated visibilities {:?} and {:?} (trait {:?})", old_vis, vis, tr);
+                            });
+
+                            if max_vis == old_vis {
+                                false
+                            } else {
+                                mark::hit!(upgrade_underscore_visibility);
+                                true
+                            }
+                        }
+                    };
+
+                    if should_update {
+                        changed = true;
+                        self.def_map.modules[module_id].scope.push_unnamed_trait(tr, vis);
+                    }
+                }
+            }
+        }
+
+        if !changed {
+            return;
+        }
+        let glob_imports = self
+            .glob_imports
+            .get(&module_id)
+            .into_iter()
+            .flat_map(|v| v.iter())
+            .filter(|(glob_importing_module, _)| {
+                // we know all resolutions have the same visibility (`vis`), so we
+                // just need to check that once
+                vis.is_visible_from_def_map(&self.def_map, *glob_importing_module)
+            })
+            .cloned()
+            .collect::<Vec<_>>();
+
+        for (glob_importing_module, glob_import_vis) in glob_imports {
+            self.update_recursive(
+                glob_importing_module,
+                resolutions,
+                glob_import_vis,
+                ImportType::Glob,
+                depth + 1,
+            );
+        }
+    }
+
+    fn resolve_macros(&mut self) -> ReachedFixedPoint {
+        let mut macros = std::mem::replace(&mut self.unexpanded_macros, Vec::new());
+        let mut attribute_macros =
+            std::mem::replace(&mut self.unexpanded_attribute_macros, Vec::new());
+        let mut resolved = Vec::new();
+        let mut res = ReachedFixedPoint::Yes;
+        macros.retain(|directive| {
+            if let Some(call_id) = directive.legacy {
+                res = ReachedFixedPoint::No;
+                resolved.push((directive.module_id, call_id, directive.depth));
+                return false;
+            }
+
+            if let Some(call_id) =
+                directive.ast_id.as_call_id(self.db, self.def_map.krate, |path| {
+                    let resolved_res = self.def_map.resolve_path_fp_with_macro(
+                        self.db,
+                        ResolveMode::Other,
+                        directive.module_id,
+                        &path,
+                        BuiltinShadowMode::Module,
+                    );
+                    resolved_res.resolved_def.take_macros()
+                })
+            {
+                resolved.push((directive.module_id, call_id, directive.depth));
+                res = ReachedFixedPoint::No;
+                return false;
+            }
+
+            true
+        });
+        attribute_macros.retain(|directive| {
+            if let Some(call_id) =
+                directive.ast_id.as_call_id(self.db, self.def_map.krate, |path| {
+                    self.resolve_attribute_macro(&directive, &path)
+                })
+            {
+                resolved.push((directive.module_id, call_id, 0));
+                res = ReachedFixedPoint::No;
+                return false;
+            }
+
+            true
+        });
+
+        self.unexpanded_macros = macros;
+        self.unexpanded_attribute_macros = attribute_macros;
+
+        for (module_id, macro_call_id, depth) in resolved {
+            self.collect_macro_expansion(module_id, macro_call_id, depth);
+        }
+
+        res
+    }
+
+    fn resolve_attribute_macro(
+        &self,
+        directive: &DeriveDirective,
+        path: &ModPath,
+    ) -> Option<MacroDefId> {
+        if let Some(name) = path.as_ident() {
+            // FIXME this should actually be handled with the normal name
+            // resolution; the std lib defines built-in stubs for the derives,
+            // but these are new-style `macro`s, which we don't support yet
+            if let Some(def_id) = find_builtin_derive(name) {
+                return Some(def_id);
+            }
+        }
+        let resolved_res = self.def_map.resolve_path_fp_with_macro(
+            self.db,
+            ResolveMode::Other,
+            directive.module_id,
+            &path,
+            BuiltinShadowMode::Module,
+        );
+
+        resolved_res.resolved_def.take_macros()
+    }
+
+    fn collect_macro_expansion(
+        &mut self,
+        module_id: LocalModuleId,
+        macro_call_id: MacroCallId,
+        depth: usize,
+    ) {
+        if depth > EXPANSION_DEPTH_LIMIT {
+            mark::hit!(macro_expansion_overflow);
+            log::warn!("macro expansion is too deep");
+            return;
+        }
+        let file_id: HirFileId = macro_call_id.as_file();
+        let item_tree = self.db.item_tree(file_id);
+        let mod_dir = self.mod_dirs[&module_id].clone();
+        ModCollector {
+            def_collector: &mut *self,
+            macro_depth: depth,
+            file_id,
+            module_id,
+            item_tree: &item_tree,
+            mod_dir,
+        }
+        .collect(item_tree.top_level_items());
+    }
+
+    fn finish(self) -> CrateDefMap {
+        self.def_map
+    }
+}
+
+/// Walks a single module, populating defs, imports and macros
+struct ModCollector<'a, 'b> {
+    def_collector: &'a mut DefCollector<'b>,
+    macro_depth: usize,
+    module_id: LocalModuleId,
+    file_id: HirFileId,
+    item_tree: &'a ItemTree,
+    mod_dir: ModDir,
+}
+
+impl ModCollector<'_, '_> {
+    fn collect(&mut self, items: &[ModItem]) {
+        // Note: don't assert that inserted value is fresh: it's simply not true
+        // for macros.
+        self.def_collector.mod_dirs.insert(self.module_id, self.mod_dir.clone());
+
+        // Prelude module is always considered to be `#[macro_use]`.
+        if let Some(prelude_module) = self.def_collector.def_map.prelude {
+            if prelude_module.krate != self.def_collector.def_map.krate {
+                mark::hit!(prelude_is_macro_use);
+                self.def_collector.import_all_macros_exported(self.module_id, prelude_module.krate);
+            }
+        }
+
+        // This should be processed eagerly instead of deferred to resolving.
+        // `#[macro_use] extern crate` is hoisted to imports macros before collecting
+        // any other items.
+        for item in items {
+            if self.is_cfg_enabled(self.item_tree.attrs((*item).into())) {
+                if let ModItem::ExternCrate(id) = item {
+                    let import = self.item_tree[*id].clone();
+                    if import.is_macro_use {
+                        self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+                    }
+                }
+            }
+        }
+
+        for &item in items {
+            let attrs = self.item_tree.attrs(item.into());
+            if self.is_cfg_enabled(attrs) {
+                let module =
+                    ModuleId { krate: self.def_collector.def_map.krate, local_id: self.module_id };
+                let container = ContainerId::ModuleId(module);
+
+                let mut def = None;
+                match item {
+                    ModItem::Mod(m) => self.collect_module(&self.item_tree[m], attrs),
+                    ModItem::Import(import_id) => {
+                        self.def_collector.unresolved_imports.push(ImportDirective {
+                            module_id: self.module_id,
+                            import: Import::from_use(&self.item_tree, import_id),
+                            status: PartialResolvedImport::Unresolved,
+                        })
+                    }
+                    ModItem::ExternCrate(import_id) => {
+                        self.def_collector.unresolved_imports.push(ImportDirective {
+                            module_id: self.module_id,
+                            import: Import::from_extern_crate(&self.item_tree, import_id),
+                            status: PartialResolvedImport::Unresolved,
+                        })
+                    }
+                    ModItem::MacroCall(mac) => self.collect_macro(&self.item_tree[mac]),
+                    ModItem::Impl(imp) => {
+                        let module = ModuleId {
+                            krate: self.def_collector.def_map.krate,
+                            local_id: self.module_id,
+                        };
+                        let container = ContainerId::ModuleId(module);
+                        let impl_id = ImplLoc { container, id: ItemTreeId::new(self.file_id, imp) }
+                            .intern(self.def_collector.db);
+                        self.def_collector.def_map.modules[self.module_id]
+                            .scope
+                            .define_impl(impl_id)
+                    }
+                    ModItem::Function(id) => {
+                        let func = &self.item_tree[id];
+                        def = Some(DefData {
+                            id: FunctionLoc {
+                                container: container.into(),
+                                id: ItemTreeId::new(self.file_id, id),
+                            }
+                            .intern(self.def_collector.db)
+                            .into(),
+                            name: &func.name,
+                            visibility: &self.item_tree[func.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                    ModItem::Struct(id) => {
+                        let it = &self.item_tree[id];
+
+                        // FIXME: check attrs to see if this is an attribute macro invocation;
+                        // in which case we don't add the invocation, just a single attribute
+                        // macro invocation
+                        self.collect_derives(attrs, it.ast_id.upcast());
+
+                        def = Some(DefData {
+                            id: StructLoc { container, id: ItemTreeId::new(self.file_id, id) }
+                                .intern(self.def_collector.db)
+                                .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: it.kind != StructDefKind::Record,
+                        });
+                    }
+                    ModItem::Union(id) => {
+                        let it = &self.item_tree[id];
+
+                        // FIXME: check attrs to see if this is an attribute macro invocation;
+                        // in which case we don't add the invocation, just a single attribute
+                        // macro invocation
+                        self.collect_derives(attrs, it.ast_id.upcast());
+
+                        def = Some(DefData {
+                            id: UnionLoc { container, id: ItemTreeId::new(self.file_id, id) }
+                                .intern(self.def_collector.db)
+                                .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                    ModItem::Enum(id) => {
+                        let it = &self.item_tree[id];
+
+                        // FIXME: check attrs to see if this is an attribute macro invocation;
+                        // in which case we don't add the invocation, just a single attribute
+                        // macro invocation
+                        self.collect_derives(attrs, it.ast_id.upcast());
+
+                        def = Some(DefData {
+                            id: EnumLoc { container, id: ItemTreeId::new(self.file_id, id) }
+                                .intern(self.def_collector.db)
+                                .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                    ModItem::Const(id) => {
+                        let it = &self.item_tree[id];
+
+                        if let Some(name) = &it.name {
+                            def = Some(DefData {
+                                id: ConstLoc {
+                                    container: container.into(),
+                                    id: ItemTreeId::new(self.file_id, id),
+                                }
+                                .intern(self.def_collector.db)
+                                .into(),
+                                name,
+                                visibility: &self.item_tree[it.visibility],
+                                has_constructor: false,
+                            });
+                        }
+                    }
+                    ModItem::Static(id) => {
+                        let it = &self.item_tree[id];
+
+                        def = Some(DefData {
+                            id: StaticLoc { container, id: ItemTreeId::new(self.file_id, id) }
+                                .intern(self.def_collector.db)
+                                .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                    ModItem::Trait(id) => {
+                        let it = &self.item_tree[id];
+
+                        def = Some(DefData {
+                            id: TraitLoc { container, id: ItemTreeId::new(self.file_id, id) }
+                                .intern(self.def_collector.db)
+                                .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                    ModItem::TypeAlias(id) => {
+                        let it = &self.item_tree[id];
+
+                        def = Some(DefData {
+                            id: TypeAliasLoc {
+                                container: container.into(),
+                                id: ItemTreeId::new(self.file_id, id),
+                            }
+                            .intern(self.def_collector.db)
+                            .into(),
+                            name: &it.name,
+                            visibility: &self.item_tree[it.visibility],
+                            has_constructor: false,
+                        });
+                    }
+                }
+
+                if let Some(DefData { id, name, visibility, has_constructor }) = def {
+                    self.def_collector.def_map.modules[self.module_id].scope.define_def(id);
+                    let vis = self
+                        .def_collector
+                        .def_map
+                        .resolve_visibility(self.def_collector.db, self.module_id, visibility)
+                        .unwrap_or(Visibility::Public);
+                    self.def_collector.update(
+                        self.module_id,
+                        &[(Some(name.clone()), PerNs::from_def(id, vis, has_constructor))],
+                        vis,
+                        ImportType::Named,
+                    )
+                }
+            }
+        }
+    }
+
+    fn collect_module(&mut self, module: &Mod, attrs: &Attrs) {
+        let path_attr = attrs.by_key("path").string_value();
+        let is_macro_use = attrs.by_key("macro_use").exists();
+        match &module.kind {
+            // inline module, just recurse
+            ModKind::Inline { items } => {
+                let module_id = self.push_child_module(
+                    module.name.clone(),
+                    AstId::new(self.file_id, module.ast_id),
+                    None,
+                    &self.item_tree[module.visibility],
+                );
+
+                ModCollector {
+                    def_collector: &mut *self.def_collector,
+                    macro_depth: self.macro_depth,
+                    module_id,
+                    file_id: self.file_id,
+                    item_tree: self.item_tree,
+                    mod_dir: self.mod_dir.descend_into_definition(&module.name, path_attr),
+                }
+                .collect(&*items);
+                if is_macro_use {
+                    self.import_all_legacy_macros(module_id);
+                }
+            }
+            // out of line module, resolve, parse and recurse
+            ModKind::Outline {} => {
+                let ast_id = AstId::new(self.file_id, module.ast_id);
+                match self.mod_dir.resolve_declaration(
+                    self.def_collector.db,
+                    self.file_id,
+                    &module.name,
+                    path_attr,
+                ) {
+                    Ok((file_id, is_mod_rs, mod_dir)) => {
+                        let module_id = self.push_child_module(
+                            module.name.clone(),
+                            ast_id,
+                            Some((file_id, is_mod_rs)),
+                            &self.item_tree[module.visibility],
+                        );
+                        let item_tree = self.def_collector.db.item_tree(file_id.into());
+                        ModCollector {
+                            def_collector: &mut *self.def_collector,
+                            macro_depth: self.macro_depth,
+                            module_id,
+                            file_id: file_id.into(),
+                            item_tree: &item_tree,
+                            mod_dir,
+                        }
+                        .collect(item_tree.top_level_items());
+                        if is_macro_use {
+                            self.import_all_legacy_macros(module_id);
+                        }
+                    }
+                    Err(candidate) => self.def_collector.def_map.diagnostics.push(
+                        DefDiagnostic::UnresolvedModule {
+                            module: self.module_id,
+                            declaration: ast_id,
+                            candidate,
+                        },
+                    ),
+                };
+            }
+        }
+    }
+
+    fn push_child_module(
+        &mut self,
+        name: Name,
+        declaration: AstId<ast::Module>,
+        definition: Option<(FileId, bool)>,
+        visibility: &crate::visibility::RawVisibility,
+    ) -> LocalModuleId {
+        let vis = self
+            .def_collector
+            .def_map
+            .resolve_visibility(self.def_collector.db, self.module_id, visibility)
+            .unwrap_or(Visibility::Public);
+        let modules = &mut self.def_collector.def_map.modules;
+        let res = modules.alloc(ModuleData::default());
+        modules[res].parent = Some(self.module_id);
+        modules[res].origin = match definition {
+            None => ModuleOrigin::Inline { definition: declaration },
+            Some((definition, is_mod_rs)) => {
+                ModuleOrigin::File { declaration, definition, is_mod_rs }
+            }
+        };
+        for (name, mac) in modules[self.module_id].scope.collect_legacy_macros() {
+            modules[res].scope.define_legacy_macro(name, mac)
+        }
+        modules[self.module_id].children.insert(name.clone(), res);
+        let module = ModuleId { krate: self.def_collector.def_map.krate, local_id: res };
+        let def: ModuleDefId = module.into();
+        self.def_collector.def_map.modules[self.module_id].scope.define_def(def);
+        self.def_collector.update(
+            self.module_id,
+            &[(Some(name), PerNs::from_def(def, vis, false))],
+            vis,
+            ImportType::Named,
+        );
+        res
+    }
+
+    fn collect_derives(&mut self, attrs: &Attrs, ast_id: FileAstId<ast::Item>) {
+        for derive_subtree in attrs.by_key("derive").tt_values() {
+            // for #[derive(Copy, Clone)], `derive_subtree` is the `(Copy, Clone)` subtree
+            for tt in &derive_subtree.token_trees {
+                let ident = match &tt {
+                    tt::TokenTree::Leaf(tt::Leaf::Ident(ident)) => ident,
+                    tt::TokenTree::Leaf(tt::Leaf::Punct(_)) => continue, // , is ok
+                    _ => continue, // anything else would be an error (which we currently ignore)
+                };
+                let path = ModPath::from_tt_ident(ident);
+
+                let ast_id = AstIdWithPath::new(self.file_id, ast_id, path);
+                self.def_collector
+                    .unexpanded_attribute_macros
+                    .push(DeriveDirective { module_id: self.module_id, ast_id });
+            }
+        }
+    }
+
+    fn collect_macro(&mut self, mac: &MacroCall) {
+        let mut ast_id = AstIdWithPath::new(self.file_id, mac.ast_id, mac.path.clone());
+
+        // Case 0: builtin macros
+        if mac.is_builtin {
+            if let Some(name) = &mac.name {
+                let krate = self.def_collector.def_map.krate;
+                if let Some(macro_id) = find_builtin_macro(name, krate, ast_id.ast_id) {
+                    self.def_collector.define_macro(
+                        self.module_id,
+                        name.clone(),
+                        macro_id,
+                        mac.is_export,
+                    );
+                    return;
+                }
+            }
+        }
+
+        // Case 1: macro rules, define a macro in crate-global mutable scope
+        if is_macro_rules(&mac.path) {
+            if let Some(name) = &mac.name {
+                let macro_id = MacroDefId {
+                    ast_id: Some(ast_id.ast_id),
+                    krate: Some(self.def_collector.def_map.krate),
+                    kind: MacroDefKind::Declarative,
+                    local_inner: mac.is_local_inner,
+                };
+                self.def_collector.define_macro(
+                    self.module_id,
+                    name.clone(),
+                    macro_id,
+                    mac.is_export,
+                );
+            }
+            return;
+        }
+
+        // Case 2: try to resolve in legacy scope and expand macro_rules
+        if let Some(macro_call_id) =
+            ast_id.as_call_id(self.def_collector.db, self.def_collector.def_map.krate, |path| {
+                path.as_ident().and_then(|name| {
+                    self.def_collector.def_map[self.module_id].scope.get_legacy_macro(&name)
+                })
+            })
+        {
+            self.def_collector.unexpanded_macros.push(MacroDirective {
+                module_id: self.module_id,
+                ast_id,
+                legacy: Some(macro_call_id),
+                depth: self.macro_depth + 1,
+            });
+
+            return;
+        }
+
+        // Case 3: resolve in module scope, expand during name resolution.
+        // We rewrite simple path `macro_name` to `self::macro_name` to force resolve in module scope only.
+        if ast_id.path.is_ident() {
+            ast_id.path.kind = PathKind::Super(0);
+        }
+
+        self.def_collector.unexpanded_macros.push(MacroDirective {
+            module_id: self.module_id,
+            ast_id,
+            legacy: None,
+            depth: self.macro_depth + 1,
+        });
+    }
+
+    fn import_all_legacy_macros(&mut self, module_id: LocalModuleId) {
+        let macros = self.def_collector.def_map[module_id].scope.collect_legacy_macros();
+        for (name, macro_) in macros {
+            self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_);
+        }
+    }
+
+    fn is_cfg_enabled(&self, attrs: &Attrs) -> bool {
+        attrs.is_cfg_enabled(self.def_collector.cfg_options)
+    }
+}
+
+fn is_macro_rules(path: &ModPath) -> bool {
+    path.as_ident() == Some(&name![macro_rules])
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{db::DefDatabase, test_db::TestDB};
+    use arena::Arena;
+    use base_db::{fixture::WithFixture, SourceDatabase};
+
+    use super::*;
+
+    fn do_collect_defs(db: &dyn DefDatabase, def_map: CrateDefMap) -> CrateDefMap {
+        let mut collector = DefCollector {
+            db,
+            def_map,
+            glob_imports: FxHashMap::default(),
+            unresolved_imports: Vec::new(),
+            resolved_imports: Vec::new(),
+            unexpanded_macros: Vec::new(),
+            unexpanded_attribute_macros: Vec::new(),
+            mod_dirs: FxHashMap::default(),
+            cfg_options: &CfgOptions::default(),
+            proc_macros: Default::default(),
+            from_glob_import: Default::default(),
+        };
+        collector.collect();
+        collector.def_map
+    }
+
+    fn do_resolve(code: &str) -> CrateDefMap {
+        let (db, _file_id) = TestDB::with_single_file(&code);
+        let krate = db.test_crate();
+
+        let def_map = {
+            let edition = db.crate_graph()[krate].edition;
+            let mut modules: Arena<ModuleData> = Arena::default();
+            let root = modules.alloc(ModuleData::default());
+            CrateDefMap {
+                krate,
+                edition,
+                extern_prelude: FxHashMap::default(),
+                prelude: None,
+                root,
+                modules,
+                diagnostics: Vec::new(),
+            }
+        };
+        do_collect_defs(&db, def_map)
+    }
+
+    #[test]
+    fn test_macro_expand_will_stop_1() {
+        do_resolve(
+            r#"
+        macro_rules! foo {
+            ($($ty:ty)*) => { foo!($($ty)*); }
+        }
+        foo!(KABOOM);
+        "#,
+        );
+    }
+
+    #[ignore] // this test does succeed, but takes quite a while :/
+    #[test]
+    fn test_macro_expand_will_stop_2() {
+        do_resolve(
+            r#"
+        macro_rules! foo {
+            ($($ty:ty)*) => { foo!($($ty)* $($ty)*); }
+        }
+        foo!(KABOOM);
+        "#,
+        );
+    }
+}
diff --git a/crates/hir_def/src/nameres/mod_resolution.rs b/crates/hir_def/src/nameres/mod_resolution.rs
new file mode 100644
index 000000000..e8389b484
--- /dev/null
+++ b/crates/hir_def/src/nameres/mod_resolution.rs
@@ -0,0 +1,139 @@
+//! This module resolves `mod foo;` declaration to file.
+use base_db::FileId;
+use hir_expand::name::Name;
+use syntax::SmolStr;
+
+use crate::{db::DefDatabase, HirFileId};
+
+#[derive(Clone, Debug)]
+pub(super) struct ModDir {
+    /// `` for `mod.rs`, `lib.rs`
+    /// `foo/` for `foo.rs`
+    /// `foo/bar/` for `mod bar { mod x; }` nested in `foo.rs`
+    /// Invariant: path.is_empty() || path.ends_with('/')
+    dir_path: DirPath,
+    /// inside `./foo.rs`, mods with `#[path]` should *not* be relative to `./foo/`
+    root_non_dir_owner: bool,
+}
+
+impl ModDir {
+    pub(super) fn root() -> ModDir {
+        ModDir { dir_path: DirPath::empty(), root_non_dir_owner: false }
+    }
+
+    pub(super) fn descend_into_definition(
+        &self,
+        name: &Name,
+        attr_path: Option<&SmolStr>,
+    ) -> ModDir {
+        let path = match attr_path.map(|it| it.as_str()) {
+            None => {
+                let mut path = self.dir_path.clone();
+                path.push(&name.to_string());
+                path
+            }
+            Some(attr_path) => {
+                let mut path = self.dir_path.join_attr(attr_path, self.root_non_dir_owner);
+                if !(path.is_empty() || path.ends_with('/')) {
+                    path.push('/')
+                }
+                DirPath::new(path)
+            }
+        };
+        ModDir { dir_path: path, root_non_dir_owner: false }
+    }
+
+    pub(super) fn resolve_declaration(
+        &self,
+        db: &dyn DefDatabase,
+        file_id: HirFileId,
+        name: &Name,
+        attr_path: Option<&SmolStr>,
+    ) -> Result<(FileId, bool, ModDir), String> {
+        let file_id = file_id.original_file(db.upcast());
+
+        let mut candidate_files = Vec::new();
+        match attr_path {
+            Some(attr_path) => {
+                candidate_files.push(self.dir_path.join_attr(attr_path, self.root_non_dir_owner))
+            }
+            None => {
+                candidate_files.push(format!("{}{}.rs", self.dir_path.0, name));
+                candidate_files.push(format!("{}{}/mod.rs", self.dir_path.0, name));
+            }
+        };
+
+        for candidate in candidate_files.iter() {
+            if let Some(file_id) = db.resolve_path(file_id, candidate.as_str()) {
+                let is_mod_rs = candidate.ends_with("mod.rs");
+
+                let (dir_path, root_non_dir_owner) = if is_mod_rs || attr_path.is_some() {
+                    (DirPath::empty(), false)
+                } else {
+                    (DirPath::new(format!("{}/", name)), true)
+                };
+                return Ok((file_id, is_mod_rs, ModDir { dir_path, root_non_dir_owner }));
+            }
+        }
+        Err(candidate_files.remove(0))
+    }
+}
+
+#[derive(Clone, Debug)]
+struct DirPath(String);
+
+impl DirPath {
+    fn assert_invariant(&self) {
+        assert!(self.0.is_empty() || self.0.ends_with('/'));
+    }
+    fn new(repr: String) -> DirPath {
+        let res = DirPath(repr);
+        res.assert_invariant();
+        res
+    }
+    fn empty() -> DirPath {
+        DirPath::new(String::new())
+    }
+    fn push(&mut self, name: &str) {
+        self.0.push_str(name);
+        self.0.push('/');
+        self.assert_invariant();
+    }
+    fn parent(&self) -> Option<&str> {
+        if self.0.is_empty() {
+            return None;
+        };
+        let idx =
+            self.0[..self.0.len() - '/'.len_utf8()].rfind('/').map_or(0, |it| it + '/'.len_utf8());
+        Some(&self.0[..idx])
+    }
+    /// So this is the case which doesn't really work I think if we try to be
+    /// 100% platform agnostic:
+    ///
+    /// ```
+    /// mod a {
+    ///     #[path="C://sad/face"]
+    ///     mod b { mod c; }
+    /// }
+    /// ```
+    ///
+    /// Here, we need to join logical dir path to a string path from an
+    /// attribute. Ideally, we should somehow losslessly communicate the whole
+    /// construction to `FileLoader`.
+    fn join_attr(&self, mut attr: &str, relative_to_parent: bool) -> String {
+        let base = if relative_to_parent { self.parent().unwrap() } else { &self.0 };
+
+        if attr.starts_with("./") {
+            attr = &attr["./".len()..];
+        }
+        let tmp;
+        let attr = if attr.contains('\\') {
+            tmp = attr.replace('\\', "/");
+            &tmp
+        } else {
+            attr
+        };
+        let res = format!("{}{}", base, attr);
+        res
+    }
+}
diff --git a/crates/hir_def/src/nameres/path_resolution.rs b/crates/hir_def/src/nameres/path_resolution.rs
new file mode 100644
index 000000000..88e10574e
--- /dev/null
+++ b/crates/hir_def/src/nameres/path_resolution.rs
@@ -0,0 +1,330 @@
+//! This modules implements a function to resolve a path `foo::bar::baz` to a
+//! def, which is used within the name resolution.
+//!
+//! When name resolution is finished, the result of resolving a path is either
+//! `Some(def)` or `None`. However, when we are in process of resolving imports
+//! or macros, there's a third possibility:
+//!
+//!   I can't resolve this path right now, but I might be resolve this path
+//!   later, when more macros are expanded.
+//!
+//! `ReachedFixedPoint` signals about this.
+
+use std::iter::successors;
+
+use base_db::Edition;
+use hir_expand::name::Name;
+use test_utils::mark;
+
+use crate::{
+    db::DefDatabase,
+    item_scope::BUILTIN_SCOPE,
+    nameres::{BuiltinShadowMode, CrateDefMap},
+    path::{ModPath, PathKind},
+    per_ns::PerNs,
+    visibility::{RawVisibility, Visibility},
+    AdtId, CrateId, EnumVariantId, LocalModuleId, ModuleDefId, ModuleId,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum ResolveMode {
+    Import,
+    Other,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(super) enum ReachedFixedPoint {
+    Yes,
+    No,
+}
+
+#[derive(Debug, Clone)]
+pub(super) struct ResolvePathResult {
+    pub(super) resolved_def: PerNs,
+    pub(super) segment_index: Option<usize>,
+    pub(super) reached_fixedpoint: ReachedFixedPoint,
+    pub(super) krate: Option<CrateId>,
+}
+
+impl ResolvePathResult {
+    fn empty(reached_fixedpoint: ReachedFixedPoint) -> ResolvePathResult {
+        ResolvePathResult::with(PerNs::none(), reached_fixedpoint, None, None)
+    }
+
+    fn with(
+        resolved_def: PerNs,
+        reached_fixedpoint: ReachedFixedPoint,
+        segment_index: Option<usize>,
+        krate: Option<CrateId>,
+    ) -> ResolvePathResult {
+        ResolvePathResult { resolved_def, reached_fixedpoint, segment_index, krate }
+    }
+}
+
+impl CrateDefMap {
+    pub(super) fn resolve_name_in_extern_prelude(&self, name: &Name) -> PerNs {
+        self.extern_prelude
+            .get(name)
+            .map_or(PerNs::none(), |&it| PerNs::types(it, Visibility::Public))
+    }
+
+    pub(crate) fn resolve_visibility(
+        &self,
+        db: &dyn DefDatabase,
+        original_module: LocalModuleId,
+        visibility: &RawVisibility,
+    ) -> Option<Visibility> {
+        match visibility {
+            RawVisibility::Module(path) => {
+                let (result, remaining) =
+                    self.resolve_path(db, original_module, &path, BuiltinShadowMode::Module);
+                if remaining.is_some() {
+                    return None;
+                }
+                let types = result.take_types()?;
+                match types {
+                    ModuleDefId::ModuleId(m) => Some(Visibility::Module(m)),
+                    _ => {
+                        // error: visibility needs to refer to module
+                        None
+                    }
+                }
+            }
+            RawVisibility::Public => Some(Visibility::Public),
+        }
+    }
+
+    // Returns Yes if we are sure that additions to `ItemMap` wouldn't change
+    // the result.
+    pub(super) fn resolve_path_fp_with_macro(
+        &self,
+        db: &dyn DefDatabase,
+        mode: ResolveMode,
+        original_module: LocalModuleId,
+        path: &ModPath,
+        shadow: BuiltinShadowMode,
+    ) -> ResolvePathResult {
+        let mut segments = path.segments.iter().enumerate();
+        let mut curr_per_ns: PerNs = match path.kind {
+            PathKind::DollarCrate(krate) => {
+                if krate == self.krate {
+                    mark::hit!(macro_dollar_crate_self);
+                    PerNs::types(
+                        ModuleId { krate: self.krate, local_id: self.root }.into(),
+                        Visibility::Public,
+                    )
+                } else {
+                    let def_map = db.crate_def_map(krate);
+                    let module = ModuleId { krate, local_id: def_map.root };
+                    mark::hit!(macro_dollar_crate_other);
+                    PerNs::types(module.into(), Visibility::Public)
+                }
+            }
+            PathKind::Crate => PerNs::types(
+                ModuleId { krate: self.krate, local_id: self.root }.into(),
+                Visibility::Public,
+            ),
+            // plain import or absolute path in 2015: crate-relative with
+            // fallback to extern prelude (with the simplification in
+            // rust-lang/rust#57745)
+            // FIXME there must be a nicer way to write this condition
+            PathKind::Plain | PathKind::Abs
+                if self.edition == Edition::Edition2015
+                    && (path.kind == PathKind::Abs || mode == ResolveMode::Import) =>
+            {
+                let (_, segment) = match segments.next() {
+                    Some((idx, segment)) => (idx, segment),
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                log::debug!("resolving {:?} in crate root (+ extern prelude)", segment);
+                self.resolve_name_in_crate_root_or_extern_prelude(&segment)
+            }
+            PathKind::Plain => {
+                let (_, segment) = match segments.next() {
+                    Some((idx, segment)) => (idx, segment),
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                // The first segment may be a builtin type. If the path has more
+                // than one segment, we first try resolving it as a module
+                // anyway.
+                // FIXME: If the next segment doesn't resolve in the module and
+                // BuiltinShadowMode wasn't Module, then we need to try
+                // resolving it as a builtin.
+                let prefer_module =
+                    if path.segments.len() == 1 { shadow } else { BuiltinShadowMode::Module };
+
+                log::debug!("resolving {:?} in module", segment);
+                self.resolve_name_in_module(db, original_module, &segment, prefer_module)
+            }
+            PathKind::Super(lvl) => {
+                let m = successors(Some(original_module), |m| self.modules[*m].parent)
+                    .nth(lvl as usize);
+                if let Some(local_id) = m {
+                    PerNs::types(
+                        ModuleId { krate: self.krate, local_id }.into(),
+                        Visibility::Public,
+                    )
+                } else {
+                    log::debug!("super path in root module");
+                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                }
+            }
+            PathKind::Abs => {
+                // 2018-style absolute path -- only extern prelude
+                let segment = match segments.next() {
+                    Some((_, segment)) => segment,
+                    None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                };
+                if let Some(def) = self.extern_prelude.get(&segment) {
+                    log::debug!("absolute path {:?} resolved to crate {:?}", path, def);
+                    PerNs::types(*def, Visibility::Public)
+                } else {
+                    return ResolvePathResult::empty(ReachedFixedPoint::No); // extern crate declarations can add to the extern prelude
+                }
+            }
+        };
+
+        for (i, segment) in segments {
+            let (curr, vis) = match curr_per_ns.take_types_vis() {
+                Some(r) => r,
+                None => {
+                    // we still have path segments left, but the path so far
+                    // didn't resolve in the types namespace => no resolution
+                    // (don't break here because `curr_per_ns` might contain
+                    // something in the value namespace, and it would be wrong
+                    // to return that)
+                    return ResolvePathResult::empty(ReachedFixedPoint::No);
+                }
+            };
+            // resolve segment in curr
+
+            curr_per_ns = match curr {
+                ModuleDefId::ModuleId(module) => {
+                    if module.krate != self.krate {
+                        let path = ModPath {
+                            segments: path.segments[i..].to_vec(),
+                            kind: PathKind::Super(0),
+                        };
+                        log::debug!("resolving {:?} in other crate", path);
+                        let defp_map = db.crate_def_map(module.krate);
+                        let (def, s) = defp_map.resolve_path(db, module.local_id, &path, shadow);
+                        return ResolvePathResult::with(
+                            def,
+                            ReachedFixedPoint::Yes,
+                            s.map(|s| s + i),
+                            Some(module.krate),
+                        );
+                    }
+
+                    // Since it is a qualified path here, it should not contains legacy macros
+                    self[module.local_id].scope.get(&segment)
+                }
+                ModuleDefId::AdtId(AdtId::EnumId(e)) => {
+                    // enum variant
+                    mark::hit!(can_import_enum_variant);
+                    let enum_data = db.enum_data(e);
+                    match enum_data.variant(&segment) {
+                        Some(local_id) => {
+                            let variant = EnumVariantId { parent: e, local_id };
+                            match &*enum_data.variants[local_id].variant_data {
+                                crate::adt::VariantData::Record(_) => {
+                                    PerNs::types(variant.into(), Visibility::Public)
+                                }
+                                crate::adt::VariantData::Tuple(_)
+                                | crate::adt::VariantData::Unit => {
+                                    PerNs::both(variant.into(), variant.into(), Visibility::Public)
+                                }
+                            }
+                        }
+                        None => {
+                            return ResolvePathResult::with(
+                                PerNs::types(e.into(), vis),
+                                ReachedFixedPoint::Yes,
+                                Some(i),
+                                Some(self.krate),
+                            );
+                        }
+                    }
+                }
+                s => {
+                    // could be an inherent method call in UFCS form
+                    // (`Struct::method`), or some other kind of associated item
+                    log::debug!(
+                        "path segment {:?} resolved to non-module {:?}, but is not last",
+                        segment,
+                        curr,
+                    );
+
+                    return ResolvePathResult::with(
+                        PerNs::types(s, vis),
+                        ReachedFixedPoint::Yes,
+                        Some(i),
+                        Some(self.krate),
+                    );
+                }
+            };
+        }
+
+        ResolvePathResult::with(curr_per_ns, ReachedFixedPoint::Yes, None, Some(self.krate))
+    }
+
+    fn resolve_name_in_module(
+        &self,
+        db: &dyn DefDatabase,
+        module: LocalModuleId,
+        name: &Name,
+        shadow: BuiltinShadowMode,
+    ) -> PerNs {
+        // Resolve in:
+        //  - legacy scope of macro
+        //  - current module / scope
+        //  - extern prelude
+        //  - std prelude
+        let from_legacy_macro = self[module]
+            .scope
+            .get_legacy_macro(name)
+            .map_or_else(PerNs::none, |m| PerNs::macros(m, Visibility::Public));
+        let from_scope = self[module].scope.get(name);
+        let from_builtin = BUILTIN_SCOPE.get(name).copied().unwrap_or_else(PerNs::none);
+        let from_scope_or_builtin = match shadow {
+            BuiltinShadowMode::Module => from_scope.or(from_builtin),
+            BuiltinShadowMode::Other => {
+                if let Some(ModuleDefId::ModuleId(_)) = from_scope.take_types() {
+                    from_builtin.or(from_scope)
+                } else {
+                    from_scope.or(from_builtin)
+                }
+            }
+        };
+        let from_extern_prelude = self
+            .extern_prelude
+            .get(name)
+            .map_or(PerNs::none(), |&it| PerNs::types(it, Visibility::Public));
+        let from_prelude = self.resolve_in_prelude(db, name);
+
+        from_legacy_macro.or(from_scope_or_builtin).or(from_extern_prelude).or(from_prelude)
+    }
+
+    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> PerNs {
+        let from_crate_root = self[self.root].scope.get(name);
+        let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
+
+        from_crate_root.or(from_extern_prelude)
+    }
+
+    fn resolve_in_prelude(&self, db: &dyn DefDatabase, name: &Name) -> PerNs {
+        if let Some(prelude) = self.prelude {
+            let keep;
+            let def_map = if prelude.krate == self.krate {
+                self
+            } else {
+                // Extend lifetime
+                keep = db.crate_def_map(prelude.krate);
+                &keep
+            };
+            def_map[prelude.local_id].scope.get(name)
+        } else {
+            PerNs::none()
+        }
+    }
+}
diff --git a/crates/hir_def/src/nameres/tests.rs b/crates/hir_def/src/nameres/tests.rs
new file mode 100644
index 000000000..8aaf7a158
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests.rs
@@ -0,0 +1,690 @@
+mod globs;
+mod incremental;
+mod macros;
+mod mod_resolution;
+mod primitives;
+
+use std::sync::Arc;
+
+use base_db::{fixture::WithFixture, SourceDatabase};
+use expect_test::{expect, Expect};
+use test_utils::mark;
+
+use crate::{db::DefDatabase, nameres::*, test_db::TestDB};
+
+fn compute_crate_def_map(fixture: &str) -> Arc<CrateDefMap> {
+    let db = TestDB::with_files(fixture);
+    let krate = db.crate_graph().iter().next().unwrap();
+    db.crate_def_map(krate)
+}
+
+fn check(ra_fixture: &str, expect: Expect) {
+    let db = TestDB::with_files(ra_fixture);
+    let krate = db.crate_graph().iter().next().unwrap();
+    let actual = db.crate_def_map(krate).dump();
+    expect.assert_eq(&actual);
+}
+
+#[test]
+fn crate_def_map_smoke_test() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+struct S;
+use crate::foo::bar::E;
+use self::E::V;
+
+//- /foo/mod.rs
+pub mod bar;
+fn f() {}
+
+//- /foo/bar.rs
+pub struct Baz;
+
+union U { to_be: bool, not_to_be: u8 }
+enum E { V }
+
+extern {
+    static EXT: u8;
+    fn ext();
+}
+"#,
+        expect![[r#"
+            crate
+            E: t
+            S: t v
+            V: t v
+            foo: t
+
+            crate::foo
+            bar: t
+            f: v
+
+            crate::foo::bar
+            Baz: t v
+            E: t
+            EXT: v
+            U: t
+            ext: v
+        "#]],
+    );
+}
+
+#[test]
+fn crate_def_map_super_super() {
+    check(
+        r#"
+mod a {
+    const A: usize = 0;
+    mod b {
+        const B: usize = 0;
+        mod c {
+            use super::super::*;
+        }
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            a: t
+
+            crate::a
+            A: v
+            b: t
+
+            crate::a::b
+            B: v
+            c: t
+
+            crate::a::b::c
+            A: v
+            b: t
+        "#]],
+    );
+}
+
+#[test]
+fn crate_def_map_fn_mod_same_name() {
+    check(
+        r#"
+mod m {
+    pub mod z {}
+    pub fn z() {}
+}
+"#,
+        expect![[r#"
+            crate
+            m: t
+
+            crate::m
+            z: t v
+
+            crate::m::z
+        "#]],
+    );
+}
+
+#[test]
+fn bogus_paths() {
+    mark::check!(bogus_paths);
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+struct S;
+use self;
+
+//- /foo/mod.rs
+use super;
+use crate;
+"#,
+        expect![[r#"
+            crate
+            S: t v
+            foo: t
+
+            crate::foo
+        "#]],
+    );
+}
+
+#[test]
+fn use_as() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use crate::foo::Baz as Foo;
+
+//- /foo/mod.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Foo: t v
+            foo: t
+
+            crate::foo
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn use_trees() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use crate::foo::bar::{Baz, Quux};
+
+//- /foo/mod.rs
+pub mod bar;
+
+//- /foo/bar.rs
+pub struct Baz;
+pub enum Quux {};
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            Quux: t
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+            Quux: t
+        "#]],
+    );
+}
+
+#[test]
+fn re_exports() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use self::foo::Baz;
+
+//- /foo/mod.rs
+pub mod bar;
+pub use self::bar::Baz;
+
+//- /foo/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn std_prelude() {
+    mark::check!(std_prelude);
+    check(
+        r#"
+//- /main.rs crate:main deps:test_crate
+use Foo::*;
+
+//- /lib.rs crate:test_crate
+mod prelude;
+#[prelude_import]
+use prelude::*;
+
+//- /prelude.rs
+pub enum Foo { Bar, Baz };
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn can_import_enum_variant() {
+    mark::check!(can_import_enum_variant);
+    check(
+        r#"
+enum E { V }
+use self::E::V;
+"#,
+        expect![[r#"
+            crate
+            E: t
+            V: t v
+        "#]],
+    );
+}
+
+#[test]
+fn edition_2015_imports() {
+    check(
+        r#"
+//- /main.rs crate:main deps:other_crate edition:2015
+mod foo;
+mod bar;
+
+//- /bar.rs
+struct Bar;
+
+//- /foo.rs
+use bar::Bar;
+use other_crate::FromLib;
+
+//- /lib.rs crate:other_crate edition:2018
+struct FromLib;
+"#,
+        expect![[r#"
+            crate
+            bar: t
+            foo: t
+
+            crate::bar
+            Bar: t v
+
+            crate::foo
+            Bar: t v
+            FromLib: t v
+        "#]],
+    );
+}
+
+#[test]
+fn item_map_using_self() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use crate::foo::bar::Baz::{self};
+
+//- /foo/mod.rs
+pub mod bar;
+
+//- /foo/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn item_map_across_crates() {
+    check(
+        r#"
+//- /main.rs crate:main deps:test_crate
+use test_crate::Baz;
+
+//- /lib.rs crate:test_crate
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn extern_crate_rename() {
+    check(
+        r#"
+//- /main.rs crate:main deps:alloc
+extern crate alloc as alloc_crate;
+mod alloc;
+mod sync;
+
+//- /sync.rs
+use alloc_crate::Arc;
+
+//- /lib.rs crate:alloc
+struct Arc;
+"#,
+        expect![[r#"
+            crate
+            alloc_crate: t
+            sync: t
+
+            crate::sync
+            Arc: t v
+        "#]],
+    );
+}
+
+#[test]
+fn extern_crate_rename_2015_edition() {
+    check(
+        r#"
+//- /main.rs crate:main deps:alloc edition:2015
+extern crate alloc as alloc_crate;
+mod alloc;
+mod sync;
+
+//- /sync.rs
+use alloc_crate::Arc;
+
+//- /lib.rs crate:alloc
+struct Arc;
+"#,
+        expect![[r#"
+            crate
+            alloc_crate: t
+            sync: t
+
+            crate::sync
+            Arc: t v
+        "#]],
+    );
+}
+
+#[test]
+fn reexport_across_crates() {
+    check(
+        r#"
+//- /main.rs crate:main deps:test_crate
+use test_crate::Baz;
+
+//- /lib.rs crate:test_crate
+pub use foo::Baz;
+mod foo;
+
+//- /foo.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn values_dont_shadow_extern_crates() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+fn foo() {}
+use foo::Bar;
+
+//- /foo/lib.rs crate:foo
+pub struct Bar;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            foo: v
+        "#]],
+    );
+}
+
+#[test]
+fn std_prelude_takes_precedence_above_core_prelude() {
+    check(
+        r#"
+//- /main.rs crate:main deps:core,std
+use {Foo, Bar};
+
+//- /std.rs crate:std deps:core
+#[prelude_import]
+pub use self::prelude::*;
+mod prelude {
+    pub struct Foo;
+    pub use core::prelude::Bar;
+}
+
+//- /core.rs crate:core
+#[prelude_import]
+pub use self::prelude::*;
+mod prelude {
+    pub struct Bar;
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Foo: t v
+        "#]],
+    );
+}
+
+#[test]
+fn cfg_not_test() {
+    check(
+        r#"
+//- /main.rs crate:main deps:std
+use {Foo, Bar, Baz};
+
+//- /lib.rs crate:std
+#[prelude_import]
+pub use self::prelude::*;
+mod prelude {
+    #[cfg(test)]
+    pub struct Foo;
+    #[cfg(not(test))]
+    pub struct Bar;
+    #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+    pub struct Baz;
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Baz: _
+            Foo: _
+        "#]],
+    );
+}
+
+#[test]
+fn cfg_test() {
+    check(
+        r#"
+//- /main.rs crate:main deps:std
+use {Foo, Bar, Baz};
+
+//- /lib.rs crate:std cfg:test,feature=foo,feature=bar,opt=42
+#[prelude_import]
+pub use self::prelude::*;
+mod prelude {
+    #[cfg(test)]
+    pub struct Foo;
+    #[cfg(not(test))]
+    pub struct Bar;
+    #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+    pub struct Baz;
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: _
+            Baz: t v
+            Foo: t v
+        "#]],
+    );
+}
+
+#[test]
+fn infer_multiple_namespace() {
+    check(
+        r#"
+//- /main.rs
+mod a {
+    pub type T = ();
+    pub use crate::b::*;
+}
+
+use crate::a::T;
+
+mod b {
+    pub const T: () = ();
+}
+"#,
+        expect![[r#"
+            crate
+            T: t v
+            a: t
+            b: t
+
+            crate::b
+            T: v
+
+            crate::a
+            T: t v
+        "#]],
+    );
+}
+
+#[test]
+fn underscore_import() {
+    check(
+        r#"
+//- /main.rs
+use tr::Tr as _;
+use tr::Tr2 as _;
+
+mod tr {
+    pub trait Tr {}
+    pub trait Tr2 {}
+}
+    "#,
+        expect![[r#"
+            crate
+            _: t
+            _: t
+            tr: t
+
+            crate::tr
+            Tr: t
+            Tr2: t
+        "#]],
+    );
+}
+
+#[test]
+fn underscore_reexport() {
+    check(
+        r#"
+//- /main.rs
+mod tr {
+    pub trait PubTr {}
+    pub trait PrivTr {}
+}
+mod reex {
+    use crate::tr::PrivTr as _;
+    pub use crate::tr::PubTr as _;
+}
+use crate::reex::*;
+    "#,
+        expect![[r#"
+            crate
+            _: t
+            reex: t
+            tr: t
+
+            crate::tr
+            PrivTr: t
+            PubTr: t
+
+            crate::reex
+            _: t
+            _: t
+        "#]],
+    );
+}
+
+#[test]
+fn underscore_pub_crate_reexport() {
+    mark::check!(upgrade_underscore_visibility);
+    check(
+        r#"
+//- /main.rs crate:main deps:lib
+use lib::*;
+
+//- /lib.rs crate:lib
+use tr::Tr as _;
+pub use tr::Tr as _;
+
+mod tr {
+    pub trait Tr {}
+}
+    "#,
+        expect![[r#"
+            crate
+            _: t
+        "#]],
+    );
+}
+
+#[test]
+fn underscore_nontrait() {
+    check(
+        r#"
+//- /main.rs
+mod m {
+    pub struct Struct;
+    pub enum Enum {}
+    pub const CONST: () = ();
+}
+use crate::m::{Struct as _, Enum as _, CONST as _};
+    "#,
+        expect![[r#"
+            crate
+            m: t
+
+            crate::m
+            CONST: v
+            Enum: t
+            Struct: t v
+        "#]],
+    );
+}
+
+#[test]
+fn underscore_name_conflict() {
+    check(
+        r#"
+//- /main.rs
+struct Tr;
+
+use tr::Tr as _;
+
+mod tr {
+    pub trait Tr {}
+}
+    "#,
+        expect![[r#"
+            crate
+            _: t
+            Tr: t v
+            tr: t
+
+            crate::tr
+            Tr: t
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/nameres/tests/globs.rs b/crates/hir_def/src/nameres/tests/globs.rs
new file mode 100644
index 000000000..2ae836e3c
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests/globs.rs
@@ -0,0 +1,338 @@
+use super::*;
+
+#[test]
+fn glob_1() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use foo::*;
+
+//- /foo/mod.rs
+pub mod bar;
+pub use self::bar::Baz;
+pub struct Foo;
+
+//- /foo/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            Foo: t v
+            bar: t
+            foo: t
+
+            crate::foo
+            Baz: t v
+            Foo: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_2() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use foo::*;
+
+//- /foo/mod.rs
+pub mod bar;
+pub use self::bar::*;
+pub struct Foo;
+
+//- /foo/bar.rs
+pub struct Baz;
+pub use super::*;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            Foo: t v
+            bar: t
+            foo: t
+
+            crate::foo
+            Baz: t v
+            Foo: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+            Foo: t v
+            bar: t
+        "#]],
+    );
+}
+
+#[test]
+fn glob_privacy_1() {
+    check(
+        r"
+//- /lib.rs
+mod foo;
+use foo::*;
+
+//- /foo/mod.rs
+pub mod bar;
+pub use self::bar::*;
+struct PrivateStructFoo;
+
+//- /foo/bar.rs
+pub struct Baz;
+struct PrivateStructBar;
+pub use super::*;
+",
+        expect![[r#"
+            crate
+            Baz: t v
+            bar: t
+            foo: t
+
+            crate::foo
+            Baz: t v
+            PrivateStructFoo: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+            PrivateStructBar: t v
+            PrivateStructFoo: t v
+            bar: t
+        "#]],
+    );
+}
+
+#[test]
+fn glob_privacy_2() {
+    check(
+        r"
+//- /lib.rs
+mod foo;
+use foo::*;
+use foo::bar::*;
+
+//- /foo/mod.rs
+mod bar;
+fn Foo() {};
+pub struct Foo {};
+
+//- /foo/bar.rs
+pub(super) struct PrivateBaz;
+struct PrivateBar;
+pub(crate) struct PubCrateStruct;
+",
+        expect![[r#"
+            crate
+            Foo: t
+            PubCrateStruct: t v
+            foo: t
+
+            crate::foo
+            Foo: t v
+            bar: t
+
+            crate::foo::bar
+            PrivateBar: t v
+            PrivateBaz: t v
+            PubCrateStruct: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_across_crates() {
+    mark::check!(glob_across_crates);
+    check(
+        r#"
+//- /main.rs crate:main deps:test_crate
+use test_crate::*;
+
+//- /lib.rs crate:test_crate
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_privacy_across_crates() {
+    check(
+        r#"
+//- /main.rs crate:main deps:test_crate
+use test_crate::*;
+
+//- /lib.rs crate:test_crate
+pub struct Baz;
+struct Foo;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_enum() {
+    mark::check!(glob_enum);
+    check(
+        r#"
+enum Foo { Bar, Baz }
+use self::Foo::*;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Baz: t v
+            Foo: t
+        "#]],
+    );
+}
+
+#[test]
+fn glob_enum_group() {
+    mark::check!(glob_enum_group);
+    check(
+        r#"
+enum Foo { Bar, Baz }
+use self::Foo::{*};
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Baz: t v
+            Foo: t
+        "#]],
+    );
+}
+
+#[test]
+fn glob_shadowed_def() {
+    mark::check!(import_shadowed);
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+mod bar;
+use foo::*;
+use bar::baz;
+use baz::Bar;
+
+//- /foo.rs
+pub mod baz { pub struct Foo; }
+
+//- /bar.rs
+pub mod baz { pub struct Bar; }
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            bar: t
+            baz: t
+            foo: t
+
+            crate::bar
+            baz: t
+
+            crate::bar::baz
+            Bar: t v
+
+            crate::foo
+            baz: t
+
+            crate::foo::baz
+            Foo: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_shadowed_def_reversed() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+mod bar;
+use bar::baz;
+use foo::*;
+use baz::Bar;
+
+//- /foo.rs
+pub mod baz { pub struct Foo; }
+
+//- /bar.rs
+pub mod baz { pub struct Bar; }
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            bar: t
+            baz: t
+            foo: t
+
+            crate::bar
+            baz: t
+
+            crate::bar::baz
+            Bar: t v
+
+            crate::foo
+            baz: t
+
+            crate::foo::baz
+            Foo: t v
+        "#]],
+    );
+}
+
+#[test]
+fn glob_shadowed_def_dependencies() {
+    check(
+        r#"
+mod a { pub mod foo { pub struct X; } }
+mod b { pub use super::a::foo; }
+mod c { pub mod foo { pub struct Y; } }
+mod d {
+    use super::c::foo;
+    use super::b::*;
+    use foo::Y;
+}
+"#,
+        expect![[r#"
+            crate
+            a: t
+            b: t
+            c: t
+            d: t
+
+            crate::d
+            Y: t v
+            foo: t
+
+            crate::c
+            foo: t
+
+            crate::c::foo
+            Y: t v
+
+            crate::b
+            foo: t
+
+            crate::a
+            foo: t
+
+            crate::a::foo
+            X: t v
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/nameres/tests/incremental.rs b/crates/hir_def/src/nameres/tests/incremental.rs
new file mode 100644
index 000000000..cfbc62cc4
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests/incremental.rs
@@ -0,0 +1,101 @@
+use std::sync::Arc;
+
+use base_db::SourceDatabaseExt;
+
+use super::*;
+
+fn check_def_map_is_not_recomputed(ra_fixture_initial: &str, ra_fixture_change: &str) {
+    let (mut db, pos) = TestDB::with_position(ra_fixture_initial);
+    let krate = db.test_crate();
+    {
+        let events = db.log_executed(|| {
+            db.crate_def_map(krate);
+        });
+        assert!(format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
+    db.set_file_text(pos.file_id, Arc::new(ra_fixture_change.to_string()));
+
+    {
+        let events = db.log_executed(|| {
+            db.crate_def_map(krate);
+        });
+        assert!(!format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
+}
+
+#[test]
+fn typing_inside_a_function_should_not_invalidate_def_map() {
+    check_def_map_is_not_recomputed(
+        r"
+        //- /lib.rs
+        mod foo;<|>
+
+        use crate::foo::bar::Baz;
+
+        enum E { A, B }
+        use E::*;
+
+        fn foo() -> i32 {
+            1 + 1
+        }
+        //- /foo/mod.rs
+        pub mod bar;
+
+        //- /foo/bar.rs
+        pub struct Baz;
+        ",
+        r"
+        mod foo;
+
+        use crate::foo::bar::Baz;
+
+        enum E { A, B }
+        use E::*;
+
+        fn foo() -> i32 { 92 }
+        ",
+    );
+}
+
+#[test]
+fn typing_inside_a_macro_should_not_invalidate_def_map() {
+    let (mut db, pos) = TestDB::with_position(
+        r"
+        //- /lib.rs
+        macro_rules! m {
+            ($ident:ident) => {
+                fn f() {
+                    $ident + $ident;
+                };
+            }
+        }
+        mod foo;
+
+        //- /foo/mod.rs
+        pub mod bar;
+
+        //- /foo/bar.rs
+        <|>
+        m!(X);
+        ",
+    );
+    let krate = db.test_crate();
+    {
+        let events = db.log_executed(|| {
+            let crate_def_map = db.crate_def_map(krate);
+            let (_, module_data) = crate_def_map.modules.iter().last().unwrap();
+            assert_eq!(module_data.scope.resolutions().count(), 1);
+        });
+        assert!(format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
+    db.set_file_text(pos.file_id, Arc::new("m!(Y);".to_string()));
+
+    {
+        let events = db.log_executed(|| {
+            let crate_def_map = db.crate_def_map(krate);
+            let (_, module_data) = crate_def_map.modules.iter().last().unwrap();
+            assert_eq!(module_data.scope.resolutions().count(), 1);
+        });
+        assert!(!format!("{:?}", events).contains("crate_def_map"), "{:#?}", events)
+    }
+}
diff --git a/crates/hir_def/src/nameres/tests/macros.rs b/crates/hir_def/src/nameres/tests/macros.rs
new file mode 100644
index 000000000..e0fb8bdef
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests/macros.rs
@@ -0,0 +1,669 @@
+use super::*;
+
+#[test]
+fn macro_rules_are_globally_visible() {
+    check(
+        r#"
+//- /lib.rs
+macro_rules! structs {
+    ($($i:ident),*) => {
+        $(struct $i { field: u32 } )*
+    }
+}
+structs!(Foo);
+mod nested;
+
+//- /nested.rs
+structs!(Bar, Baz);
+"#,
+        expect![[r#"
+            crate
+            Foo: t
+            nested: t
+
+            crate::nested
+            Bar: t
+            Baz: t
+        "#]],
+    );
+}
+
+#[test]
+fn macro_rules_can_define_modules() {
+    check(
+        r#"
+//- /lib.rs
+macro_rules! m {
+    ($name:ident) => { mod $name;  }
+}
+m!(n1);
+mod m { m!(n3) }
+
+//- /n1.rs
+m!(n2)
+//- /n1/n2.rs
+struct X;
+//- /m/n3.rs
+struct Y;
+"#,
+        expect![[r#"
+            crate
+            m: t
+            n1: t
+
+            crate::m
+            n3: t
+
+            crate::m::n3
+            Y: t v
+
+            crate::n1
+            n2: t
+
+            crate::n1::n2
+            X: t v
+        "#]],
+    );
+}
+
+#[test]
+fn macro_rules_from_other_crates_are_visible() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+foo::structs!(Foo, Bar)
+mod bar;
+
+//- /bar.rs
+use crate::*;
+
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! structs {
+    ($($i:ident),*) => {
+        $(struct $i { field: u32 } )*
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t
+            Foo: t
+            bar: t
+
+            crate::bar
+            Bar: t
+            Foo: t
+            bar: t
+        "#]],
+    );
+}
+
+#[test]
+fn macro_rules_export_with_local_inner_macros_are_visible() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+foo::structs!(Foo, Bar)
+mod bar;
+
+//- /bar.rs
+use crate::*;
+
+//- /lib.rs crate:foo
+#[macro_export(local_inner_macros)]
+macro_rules! structs {
+    ($($i:ident),*) => {
+        $(struct $i { field: u32 } )*
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t
+            Foo: t
+            bar: t
+
+            crate::bar
+            Bar: t
+            Foo: t
+            bar: t
+        "#]],
+    );
+}
+
+#[test]
+fn local_inner_macros_makes_local_macros_usable() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+foo::structs!(Foo, Bar);
+mod bar;
+
+//- /bar.rs
+use crate::*;
+
+//- /lib.rs crate:foo
+#[macro_export(local_inner_macros)]
+macro_rules! structs {
+    ($($i:ident),*) => {
+        inner!($($i),*);
+    }
+}
+#[macro_export]
+macro_rules! inner {
+    ($($i:ident),*) => {
+        $(struct $i { field: u32 } )*
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t
+            Foo: t
+            bar: t
+
+            crate::bar
+            Bar: t
+            Foo: t
+            bar: t
+        "#]],
+    );
+}
+
+#[test]
+fn unexpanded_macro_should_expand_by_fixedpoint_loop() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+macro_rules! baz {
+    () => {
+        use foo::bar;
+    }
+}
+foo!();
+bar!();
+baz!();
+
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! foo {
+    () => {
+        struct Foo { field: u32 }
+    }
+}
+#[macro_export]
+macro_rules! bar {
+    () => {
+        use foo::foo;
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Foo: t
+            bar: m
+            foo: m
+        "#]],
+    );
+}
+
+#[test]
+fn macro_rules_from_other_crates_are_visible_with_macro_use() {
+    mark::check!(macro_rules_from_other_crates_are_visible_with_macro_use);
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+structs!(Foo);
+structs_priv!(Bar);
+structs_not_exported!(MacroNotResolved1);
+crate::structs!(MacroNotResolved2);
+
+mod bar;
+
+#[macro_use]
+extern crate foo;
+
+//- /bar.rs
+structs!(Baz);
+crate::structs!(MacroNotResolved3);
+
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! structs {
+    ($i:ident) => { struct $i; }
+}
+
+macro_rules! structs_not_exported {
+    ($i:ident) => { struct $i; }
+}
+
+mod priv_mod {
+    #[macro_export]
+    macro_rules! structs_priv {
+        ($i:ident) => { struct $i; }
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Foo: t v
+            bar: t
+            foo: t
+
+            crate::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn prelude_is_macro_use() {
+    mark::check!(prelude_is_macro_use);
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+structs!(Foo);
+structs_priv!(Bar);
+structs_outside!(Out);
+crate::structs!(MacroNotResolved2);
+
+mod bar;
+
+//- /bar.rs
+structs!(Baz);
+crate::structs!(MacroNotResolved3);
+
+//- /lib.rs crate:foo
+#[prelude_import]
+use self::prelude::*;
+
+mod prelude {
+    #[macro_export]
+    macro_rules! structs {
+        ($i:ident) => { struct $i; }
+    }
+
+    mod priv_mod {
+        #[macro_export]
+        macro_rules! structs_priv {
+            ($i:ident) => { struct $i; }
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! structs_outside {
+    ($i:ident) => { struct $i; }
+}
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Foo: t v
+            Out: t v
+            bar: t
+
+            crate::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn prelude_cycle() {
+    check(
+        r#"
+#[prelude_import]
+use self::prelude::*;
+
+declare_mod!();
+
+mod prelude {
+    macro_rules! declare_mod {
+        () => (mod foo {})
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            prelude: t
+
+            crate::prelude
+        "#]],
+    );
+}
+
+#[test]
+fn plain_macros_are_legacy_textual_scoped() {
+    check(
+        r#"
+//- /main.rs
+mod m1;
+bar!(NotFoundNotMacroUse);
+
+mod m2 { foo!(NotFoundBeforeInside2); }
+
+macro_rules! foo {
+    ($x:ident) => { struct $x; }
+}
+foo!(Ok);
+
+mod m3;
+foo!(OkShadowStop);
+bar!(NotFoundMacroUseStop);
+
+#[macro_use]
+mod m5 {
+    #[macro_use]
+    mod m6 {
+        macro_rules! foo {
+            ($x:ident) => { fn $x() {} }
+        }
+    }
+}
+foo!(ok_double_macro_use_shadow);
+
+baz!(NotFoundBefore);
+#[macro_use]
+mod m7 {
+    macro_rules! baz {
+        ($x:ident) => { struct $x; }
+    }
+}
+baz!(OkAfter);
+
+//- /m1.rs
+foo!(NotFoundBeforeInside1);
+macro_rules! bar {
+    ($x:ident) => { struct $x; }
+}
+
+//- /m3/mod.rs
+foo!(OkAfterInside);
+macro_rules! foo {
+    ($x:ident) => { fn $x() {} }
+}
+foo!(ok_shadow);
+
+#[macro_use]
+mod m4;
+bar!(OkMacroUse);
+
+//- /m3/m4.rs
+foo!(ok_shadow_deep);
+macro_rules! bar {
+    ($x:ident) => { struct $x; }
+}
+"#,
+        expect![[r#"
+            crate
+            Ok: t v
+            OkAfter: t v
+            OkShadowStop: t v
+            m1: t
+            m2: t
+            m3: t
+            m5: t
+            m7: t
+            ok_double_macro_use_shadow: v
+
+            crate::m7
+
+            crate::m1
+
+            crate::m5
+            m6: t
+
+            crate::m5::m6
+
+            crate::m2
+
+            crate::m3
+            OkAfterInside: t v
+            OkMacroUse: t v
+            m4: t
+            ok_shadow: v
+
+            crate::m3::m4
+            ok_shadow_deep: v
+        "#]],
+    );
+}
+
+#[test]
+fn type_value_macro_live_in_different_scopes() {
+    check(
+        r#"
+#[macro_export]
+macro_rules! foo {
+    ($x:ident) => { type $x = (); }
+}
+
+foo!(foo);
+use foo as bar;
+
+use self::foo as baz;
+fn baz() {}
+"#,
+        expect![[r#"
+            crate
+            bar: t m
+            baz: t v m
+            foo: t m
+        "#]],
+    );
+}
+
+#[test]
+fn macro_use_can_be_aliased() {
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+#[macro_use]
+extern crate foo;
+
+foo!(Direct);
+bar!(Alias);
+
+//- /lib.rs crate:foo
+use crate::foo as bar;
+
+mod m {
+    #[macro_export]
+    macro_rules! foo {
+        ($x:ident) => { struct $x; }
+    }
+}
+"#,
+        expect![[r#"
+            crate
+            Alias: t v
+            Direct: t v
+            foo: t
+        "#]],
+    );
+}
+
+#[test]
+fn path_qualified_macros() {
+    check(
+        r#"
+macro_rules! foo {
+    ($x:ident) => { struct $x; }
+}
+
+crate::foo!(NotResolved);
+
+crate::bar!(OkCrate);
+bar!(OkPlain);
+alias1!(NotHere);
+m::alias1!(OkAliasPlain);
+m::alias2!(OkAliasSuper);
+m::alias3!(OkAliasCrate);
+not_found!(NotFound);
+
+mod m {
+    #[macro_export]
+    macro_rules! bar {
+        ($x:ident) => { struct $x; }
+    }
+    pub use bar as alias1;
+    pub use super::bar as alias2;
+    pub use crate::bar as alias3;
+    pub use self::bar as not_found;
+}
+"#,
+        expect![[r#"
+            crate
+            OkAliasCrate: t v
+            OkAliasPlain: t v
+            OkAliasSuper: t v
+            OkCrate: t v
+            OkPlain: t v
+            bar: m
+            m: t
+
+            crate::m
+            alias1: m
+            alias2: m
+            alias3: m
+            not_found: _
+        "#]],
+    );
+}
+
+#[test]
+fn macro_dollar_crate_is_correct_in_item() {
+    mark::check!(macro_dollar_crate_self);
+    check(
+        r#"
+//- /main.rs crate:main deps:foo
+#[macro_use]
+extern crate foo;
+
+#[macro_use]
+mod m {
+    macro_rules! current {
+        () => {
+            use $crate::Foo as FooSelf;
+        }
+    }
+}
+
+struct Foo;
+
+current!();
+not_current1!();
+foo::not_current2!();
+
+//- /lib.rs crate:foo
+mod m {
+    #[macro_export]
+    macro_rules! not_current1 {
+        () => {
+            use $crate::Bar;
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! not_current2 {
+    () => {
+        use $crate::Baz;
+    }
+}
+
+struct Bar;
+struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            Baz: t v
+            Foo: t v
+            FooSelf: t v
+            foo: t
+            m: t
+
+            crate::m
+        "#]],
+    );
+}
+
+#[test]
+fn macro_dollar_crate_is_correct_in_indirect_deps() {
+    mark::check!(macro_dollar_crate_other);
+    // From std
+    check(
+        r#"
+//- /main.rs crate:main deps:std
+foo!();
+
+//- /std.rs crate:std deps:core
+#[prelude_import]
+use self::prelude::*;
+
+pub use core::foo;
+
+mod prelude {}
+
+#[macro_use]
+mod std_macros;
+
+//- /core.rs crate:core
+#[macro_export]
+macro_rules! foo {
+    () => {
+        use $crate::bar;
+    }
+}
+
+pub struct bar;
+"#,
+        expect![[r#"
+            crate
+            bar: t v
+        "#]],
+    );
+}
+
+#[test]
+fn expand_derive() {
+    let map = compute_crate_def_map(
+        "
+        //- /main.rs
+        #[derive(Copy, Clone)]
+        struct Foo;
+        ",
+    );
+    assert_eq!(map.modules[map.root].scope.impls().len(), 2);
+}
+
+#[test]
+fn macro_expansion_overflow() {
+    mark::check!(macro_expansion_overflow);
+    check(
+        r#"
+macro_rules! a {
+    ($e:expr; $($t:tt)*) => {
+        b!($($t)*);
+    };
+    () => {};
+}
+
+macro_rules! b {
+    (static = $e:expr; $($t:tt)*) => {
+        a!($e; $($t)*);
+    };
+    () => {};
+}
+
+b! { static = #[] (); }
+"#,
+        expect![[r#"
+            crate
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/nameres/tests/mod_resolution.rs b/crates/hir_def/src/nameres/tests/mod_resolution.rs
new file mode 100644
index 000000000..1f619787e
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests/mod_resolution.rs
@@ -0,0 +1,796 @@
+use super::*;
+
+#[test]
+fn name_res_works_for_broken_modules() {
+    mark::check!(name_res_works_for_broken_modules);
+    check(
+        r"
+//- /lib.rs
+mod foo // no `;`, no body
+use self::foo::Baz;
+
+//- /foo/mod.rs
+pub mod bar;
+pub use self::bar::Baz;
+
+//- /foo/bar.rs
+pub struct Baz;
+",
+        expect![[r#"
+            crate
+            Baz: _
+            foo: t
+
+            crate::foo
+        "#]],
+    );
+}
+
+#[test]
+fn nested_module_resolution() {
+    check(
+        r#"
+//- /lib.rs
+mod n1;
+
+//- /n1.rs
+mod n2;
+
+//- /n1/n2.rs
+struct X;
+"#,
+        expect![[r#"
+            crate
+            n1: t
+
+            crate::n1
+            n2: t
+
+            crate::n1::n2
+            X: t v
+        "#]],
+    );
+}
+
+#[test]
+fn nested_module_resolution_2() {
+    check(
+        r#"
+//- /lib.rs
+mod prelude;
+mod iter;
+
+//- /prelude.rs
+pub use crate::iter::Iterator;
+
+//- /iter.rs
+pub use self::traits::Iterator;
+mod traits;
+
+//- /iter/traits.rs
+pub use self::iterator::Iterator;
+mod iterator;
+
+//- /iter/traits/iterator.rs
+pub trait Iterator;
+"#,
+        expect![[r#"
+            crate
+            iter: t
+            prelude: t
+
+            crate::iter
+            Iterator: t
+            traits: t
+
+            crate::iter::traits
+            Iterator: t
+            iterator: t
+
+            crate::iter::traits::iterator
+            Iterator: t
+
+            crate::prelude
+            Iterator: t
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_works_for_non_standard_filenames() {
+    check(
+        r#"
+//- /my_library.rs crate:my_library
+mod foo;
+use self::foo::Bar;
+
+//- /foo/mod.rs
+pub struct Bar;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            foo: t
+
+            crate::foo
+            Bar: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_works_for_raw_modules() {
+    check(
+        r#"
+//- /lib.rs
+mod r#async;
+use self::r#async::Bar;
+
+//- /async.rs
+pub struct Bar;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            async: t
+
+            crate::async
+            Bar: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_path() {
+    check(
+        r#"
+//- /lib.rs
+#[path = "bar/baz/foo.rs"]
+mod foo;
+use self::foo::Bar;
+
+//- /bar/baz/foo.rs
+pub struct Bar;
+"#,
+        expect![[r#"
+            crate
+            Bar: t v
+            foo: t
+
+            crate::foo
+            Bar: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_module_with_path_in_mod_rs() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo/mod.rs
+#[path = "baz.rs"]
+pub mod bar;
+use self::bar::Baz;
+
+//- /foo/baz.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_module_with_path_non_crate_root() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo.rs
+#[path = "baz.rs"]
+pub mod bar;
+use self::bar::Baz;
+
+//- /baz.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_module_decl_path_super() {
+    check(
+        r#"
+//- /main.rs
+#[path = "bar/baz/module.rs"]
+mod foo;
+pub struct Baz;
+
+//- /bar/baz/module.rs
+use super::Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            foo: t
+
+            crate::foo
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_explicit_path_mod_rs() {
+    check(
+        r#"
+//- /main.rs
+#[path = "module/mod.rs"]
+mod foo;
+
+//- /module/mod.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_relative_path() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo.rs
+#[path = "./sub.rs"]
+pub mod foo_bar;
+
+//- /sub.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            foo_bar: t
+
+            crate::foo::foo_bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_relative_path_2() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo/mod.rs
+#[path="../sub.rs"]
+pub mod foo_bar;
+
+//- /sub.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            foo_bar: t
+
+            crate::foo::foo_bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_relative_path_outside_root() {
+    check(
+        r#"
+//- /main.rs
+#[path="../../../../../outside.rs"]
+mod foo;
+"#,
+        expect![[r#"
+            crate
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_explicit_path_mod_rs_2() {
+    check(
+        r#"
+//- /main.rs
+#[path = "module/bar/mod.rs"]
+mod foo;
+
+//- /module/bar/mod.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_explicit_path_mod_rs_with_win_separator() {
+    check(
+        r#"
+//- /main.rs
+#[path = "module\bar\mod.rs"]
+mod foo;
+
+//- /module/bar/mod.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_with_path_attribute() {
+    check(
+        r#"
+//- /main.rs
+#[path = "models"]
+mod foo { mod bar; }
+
+//- /models/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module() {
+    check(
+        r#"
+//- /main.rs
+mod foo { mod bar; }
+
+//- /foo/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_2_with_path_attribute() {
+    check(
+        r#"
+//- /main.rs
+#[path = "models/db"]
+mod foo { mod bar; }
+
+//- /models/db/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_3() {
+    check(
+        r#"
+//- /main.rs
+#[path = "models/db"]
+mod foo {
+    #[path = "users.rs"]
+    mod bar;
+}
+
+//- /models/db/users.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_empty_path() {
+    check(
+        r#"
+//- /main.rs
+#[path = ""]
+mod foo {
+    #[path = "users.rs"]
+    mod bar;
+}
+
+//- /users.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_empty_path() {
+    check(
+        r#"
+//- /main.rs
+#[path = ""] // Should try to read `/` (a directory)
+mod foo;
+
+//- /foo.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_relative_path() {
+    check(
+        r#"
+//- /main.rs
+#[path = "./models"]
+mod foo { mod bar; }
+
+//- /models/bar.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_in_crate_root() {
+    check(
+        r#"
+//- /main.rs
+mod foo {
+    #[path = "baz.rs"]
+    mod bar;
+}
+use self::foo::bar::Baz;
+
+//- /foo/baz.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            Baz: t v
+            foo: t
+
+            crate::foo
+            bar: t
+
+            crate::foo::bar
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_in_mod_rs() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo/mod.rs
+mod bar {
+    #[path = "qwe.rs"]
+    pub mod baz;
+}
+use self::bar::baz::Baz;
+
+//- /foo/bar/qwe.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            baz: t
+
+            crate::foo::bar::baz
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_in_non_crate_root() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo.rs
+mod bar {
+    #[path = "qwe.rs"]
+    pub mod baz;
+}
+use self::bar::baz::Baz;
+
+//- /foo/bar/qwe.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            baz: t
+
+            crate::foo::bar::baz
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn module_resolution_decl_inside_inline_module_in_non_crate_root_2() {
+    check(
+        r#"
+//- /main.rs
+mod foo;
+
+//- /foo.rs
+#[path = "bar"]
+mod bar {
+    pub mod baz;
+}
+use self::bar::baz::Baz;
+
+//- /bar/baz.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+
+            crate::foo
+            Baz: t v
+            bar: t
+
+            crate::foo::bar
+            baz: t
+
+            crate::foo::bar::baz
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn unresolved_module_diagnostics() {
+    let db = TestDB::with_files(
+        r"
+        //- /lib.rs
+        mod foo;
+        mod bar;
+        mod baz {}
+        //- /foo.rs
+        ",
+    );
+    let krate = db.test_crate();
+
+    let crate_def_map = db.crate_def_map(krate);
+
+    expect![[r#"
+        [
+            UnresolvedModule {
+                module: Idx::<ModuleData>(0),
+                declaration: InFile {
+                    file_id: HirFileId(
+                        FileId(
+                            FileId(
+                                0,
+                            ),
+                        ),
+                    ),
+                    value: FileAstId::<syntax::ast::generated::nodes::Module>(1),
+                },
+                candidate: "bar.rs",
+            },
+        ]
+    "#]]
+    .assert_debug_eq(&crate_def_map.diagnostics);
+}
+
+#[test]
+fn module_resolution_decl_inside_module_in_non_crate_root_2() {
+    check(
+        r#"
+//- /main.rs
+#[path="module/m2.rs"]
+mod module;
+
+//- /module/m2.rs
+pub mod submod;
+
+//- /module/submod.rs
+pub struct Baz;
+"#,
+        expect![[r#"
+            crate
+            module: t
+
+            crate::module
+            submod: t
+
+            crate::module::submod
+            Baz: t v
+        "#]],
+    );
+}
+
+#[test]
+fn nested_out_of_line_module() {
+    check(
+        r#"
+//- /lib.rs
+mod a {
+    mod b {
+        mod c;
+    }
+}
+
+//- /a/b/c.rs
+struct X;
+"#,
+        expect![[r#"
+            crate
+            a: t
+
+            crate::a
+            b: t
+
+            crate::a::b
+            c: t
+
+            crate::a::b::c
+            X: t v
+        "#]],
+    );
+}
+
+#[test]
+fn nested_out_of_line_module_with_path() {
+    check(
+        r#"
+//- /lib.rs
+mod a {
+    #[path = "d/e"]
+    mod b {
+        mod c;
+    }
+}
+
+//- /a/d/e/c.rs
+struct X;
+"#,
+        expect![[r#"
+            crate
+            a: t
+
+            crate::a
+            b: t
+
+            crate::a::b
+            c: t
+
+            crate::a::b::c
+            X: t v
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/nameres/tests/primitives.rs b/crates/hir_def/src/nameres/tests/primitives.rs
new file mode 100644
index 000000000..215e8952d
--- /dev/null
+++ b/crates/hir_def/src/nameres/tests/primitives.rs
@@ -0,0 +1,23 @@
+use super::*;
+
+#[test]
+fn primitive_reexport() {
+    check(
+        r#"
+//- /lib.rs
+mod foo;
+use foo::int;
+
+//- /foo.rs
+pub use i32 as int;
+"#,
+        expect![[r#"
+            crate
+            foo: t
+            int: t
+
+            crate::foo
+            int: t
+        "#]],
+    );
+}