Merge #1795

1795: Make macro scope a real name scope and fix some details r=matklad a=uHOOCCOOHu

This PR make macro's module scope a real name scope in `PerNs`, instead of handling `Either<PerNs, MacroDef>` everywhere.

In `rustc`, the macro scope behave exactly the same as type and value scope.
It is valid that macros, types and values having exact the same name, and a `use` statement will import all of them. This happened to module `alloc::vec` and macro `alloc::vec!`.
So `Either` is not suitable here.

There is a trap that not only does `#[macro_use]` import all `#[macro_export] macro_rules`, but also imports all macros `use`d in the crate root.
In other words, it just _imports all macros in the module scope of crate root_. (Visibility of `use` doesn't matter.)

And it also happened to `libstd` which has `use alloc_crate::vec;` in crate root to re-export `alloc::vec`, which it both a module and a macro.
The current implementation of `#[macro_use] extern crate` doesn't work here, so that is why only macros directly from  `libstd` like `dbg!` work, while `vec!` from `liballoc` doesn't.
This PR fixes this.

Another point is that, after some tests, I figure out that _`macro_rules` does NOT define macro in current module scope at all_.
It defines itself in legacy textual scope. And if `#[macro_export]` is given, it also is defined ONLY in module scope of crate root. (Then being `macro_use`d, as mentioned above)
(Well, the nightly [Declarative Macro 2.0](https://github.com/rust-lang/rust/issues/39412) simply always define in current module scope only, just like normal items do. But it is not yet supported by us)

After this PR, in my test, all non-builtin macros are resolved now. (Hover text for documentation is available) So it fixes #1688 . Since compiler builtin macros are marked as `#[rustc_doc_only_macro]` instead of `#[macro_export]`, we can simply tweak the condition to let it resolved, but it may cause expansion error.

Some critical notes are also given in doc-comments.

<img width="447" alt="Screenshot_20190909_223859" src="https://user-images.githubusercontent.com/14816024/64540366-ac1ef600-d352-11e9-804f-566ba7559206.png">


Co-authored-by: uHOOCCOOHu <[email protected]>

7 files changed, 393 insertions, 239 deletions

diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 74546e5e2..7488d75a5 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -67,7 +67,6 @@ use test_utils::tested_by;
 use crate::{
     db::{AstDatabase, DefDatabase},
     diagnostics::DiagnosticSink,
-    either::Either,
     ids::MacroDefId,
     nameres::diagnostics::DefDiagnostic,
     AstId, BuiltinType, Crate, HirFileId, MacroDef, Module, ModuleDef, Name, Path, PathKind, Trait,
@@ -105,8 +104,6 @@ pub struct CrateDefMap {
     /// However, do we want to put it as a global variable?
     poison_macros: FxHashSet<MacroDefId>,
 
-    exported_macros: FxHashMap<Name, MacroDefId>,
-
     diagnostics: Vec<DefDiagnostic>,
 }
 
@@ -138,12 +135,6 @@ pub(crate) struct ModuleData {
 #[derive(Debug, Default, PartialEq, Eq, Clone)]
 pub struct ModuleScope {
     items: FxHashMap<Name, Resolution>,
-    /// Macros in current module scoped
-    ///
-    /// This scope works exactly the same way that item scoping does.
-    /// Macro invocation with quantified path will search in it.
-    /// See details below.
-    macros: FxHashMap<Name, MacroDef>,
     /// Macros visable in current module in legacy textual scope
     ///
     /// For macros invoked by an unquatified identifier like `bar!()`, `legacy_macros` will be searched in first.
@@ -152,6 +143,10 @@ pub struct ModuleScope {
     /// and only normal scoped `macros` will be searched in.
     ///
     /// Note that this automatically inherit macros defined textually before the definition of module itself.
+    ///
+    /// Module scoped macros will be inserted into `items` instead of here.
+    // FIXME: Macro shadowing in one module is not properly handled. Non-item place macros will
+    // be all resolved to the last one defined if shadowing happens.
     legacy_macros: FxHashMap<Name, MacroDef>,
 }
 
@@ -164,35 +159,43 @@ static BUILTIN_SCOPE: Lazy<FxHashMap<Name, Resolution>> = Lazy::new(|| {
         .collect()
 });
 
+/// Legacy macros can only be accessed through special methods like `get_legacy_macros`.
+/// Other methods will only resolve values, types and module scoped macros only.
 impl ModuleScope {
     pub fn entries<'a>(&'a self) -> impl Iterator<Item = (&'a Name, &'a Resolution)> + 'a {
         //FIXME: shadowing
         self.items.iter().chain(BUILTIN_SCOPE.iter())
     }
+
+    /// Iterate over all module scoped macros
+    pub fn macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDef)> + 'a {
+        self.items
+            .iter()
+            .filter_map(|(name, res)| res.def.get_macros().map(|macro_| (name, macro_)))
+    }
+
+    /// Iterate over all legacy textual scoped macros visable at the end of the module
+    pub fn legacy_macros<'a>(&'a self) -> impl Iterator<Item = (&'a Name, MacroDef)> + 'a {
+        self.legacy_macros.iter().map(|(name, def)| (name, *def))
+    }
+
+    /// Get a name from current module scope, legacy macros are not included
     pub fn get(&self, name: &Name) -> Option<&Resolution> {
         self.items.get(name).or_else(|| BUILTIN_SCOPE.get(name))
     }
+
     pub fn traits<'a>(&'a self) -> impl Iterator<Item = Trait> + 'a {
         self.items.values().filter_map(|r| match r.def.take_types() {
             Some(ModuleDef::Trait(t)) => Some(t),
             _ => None,
         })
     }
-    /// It resolves in module scope. Textual scoped macros are ignored here.
-    fn get_item_or_macro(&self, name: &Name) -> Option<ItemOrMacro> {
-        match (self.get(name), self.macros.get(name)) {
-            (Some(item), _) if !item.def.is_none() => Some(Either::A(item.def)),
-            (_, Some(macro_)) => Some(Either::B(*macro_)),
-            _ => None,
-        }
-    }
+
     fn get_legacy_macro(&self, name: &Name) -> Option<MacroDef> {
         self.legacy_macros.get(name).copied()
     }
 }
 
-type ItemOrMacro = Either<PerNs<ModuleDef>, MacroDef>;
-
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct Resolution {
     /// None for unresolved
@@ -201,20 +204,26 @@ pub struct Resolution {
     pub import: Option<ImportId>,
 }
 
+impl Resolution {
+    pub(crate) fn from_macro(macro_: MacroDef) -> Self {
+        Resolution { def: PerNs::macros(macro_), import: None }
+    }
+}
+
 #[derive(Debug, Clone)]
 struct ResolvePathResult {
-    resolved_def: ItemOrMacro,
+    resolved_def: PerNs<ModuleDef>,
     segment_index: Option<usize>,
     reached_fixedpoint: ReachedFixedPoint,
 }
 
 impl ResolvePathResult {
     fn empty(reached_fixedpoint: ReachedFixedPoint) -> ResolvePathResult {
-        ResolvePathResult::with(Either::A(PerNs::none()), reached_fixedpoint, None)
+        ResolvePathResult::with(PerNs::none(), reached_fixedpoint, None)
     }
 
     fn with(
-        resolved_def: ItemOrMacro,
+        resolved_def: PerNs<ModuleDef>,
         reached_fixedpoint: ReachedFixedPoint,
         segment_index: Option<usize>,
     ) -> ResolvePathResult {
@@ -234,21 +243,6 @@ enum ReachedFixedPoint {
     No,
 }
 
-/// helper function for select item or macro to use
-fn or(left: ItemOrMacro, right: ItemOrMacro) -> ItemOrMacro {
-    match (left, right) {
-        (Either::A(s), Either::A(o)) => Either::A(s.or(o)),
-        (Either::B(s), _) => Either::B(s),
-        (Either::A(s), Either::B(o)) => {
-            if !s.is_none() {
-                Either::A(s)
-            } else {
-                Either::B(o)
-            }
-        }
-    }
-}
-
 impl CrateDefMap {
     pub(crate) fn crate_def_map_query(
         // Note that this doesn't have `+ AstDatabase`!
@@ -269,7 +263,6 @@ impl CrateDefMap {
                 root,
                 modules,
                 poison_macros: FxHashSet::default(),
-                exported_macros: FxHashMap::default(),
                 diagnostics: Vec::new(),
             }
         };
@@ -328,16 +321,6 @@ impl CrateDefMap {
         path: &Path,
     ) -> (PerNs<ModuleDef>, Option<usize>) {
         let res = self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path);
-        (res.resolved_def.a().unwrap_or_else(PerNs::none), res.segment_index)
-    }
-
-    pub(crate) fn resolve_path_with_macro(
-        &self,
-        db: &impl DefDatabase,
-        original_module: CrateModuleId,
-        path: &Path,
-    ) -> (ItemOrMacro, Option<usize>) {
-        let res = self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path);
         (res.resolved_def, res.segment_index)
     }
 
@@ -351,13 +334,13 @@ impl CrateDefMap {
         path: &Path,
     ) -> ResolvePathResult {
         let mut segments = path.segments.iter().enumerate();
-        let mut curr_per_ns: ItemOrMacro = match path.kind {
+        let mut curr_per_ns: PerNs<ModuleDef> = match path.kind {
             PathKind::Crate => {
-                Either::A(PerNs::types(Module { krate: self.krate, module_id: self.root }.into()))
+                PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+            }
+            PathKind::Self_ => {
+                PerNs::types(Module { krate: self.krate, module_id: original_module }.into())
             }
-            PathKind::Self_ => Either::A(PerNs::types(
-                Module { krate: self.krate, module_id: original_module }.into(),
-            )),
             // plain import or absolute path in 2015: crate-relative with
             // fallback to extern prelude (with the simplification in
             // rust-lang/rust#57745)
@@ -379,11 +362,11 @@ impl CrateDefMap {
                     None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
                 };
                 log::debug!("resolving {:?} in module", segment);
-                self.resolve_name_in_module_with_macro(db, original_module, &segment.name)
+                self.resolve_name_in_module(db, original_module, &segment.name)
             }
             PathKind::Super => {
                 if let Some(p) = self.modules[original_module].parent {
-                    Either::A(PerNs::types(Module { krate: self.krate, module_id: p }.into()))
+                    PerNs::types(Module { krate: self.krate, module_id: p }.into())
                 } else {
                     log::debug!("super path in root module");
                     return ResolvePathResult::empty(ReachedFixedPoint::Yes);
@@ -397,7 +380,7 @@ impl CrateDefMap {
                 };
                 if let Some(def) = self.extern_prelude.get(&segment.name) {
                     log::debug!("absolute path {:?} resolved to crate {:?}", path, def);
-                    Either::A(PerNs::types(*def))
+                    PerNs::types(*def)
                 } else {
                     return ResolvePathResult::empty(ReachedFixedPoint::No); // extern crate declarations can add to the extern prelude
                 }
@@ -405,7 +388,7 @@ impl CrateDefMap {
         };
 
         for (i, segment) in segments {
-            let curr = match curr_per_ns.as_ref().a().and_then(|m| m.as_ref().take_types()) {
+            let curr = match curr_per_ns.as_ref().take_types() {
                 Some(r) => r,
                 None => {
                     // we still have path segments left, but the path so far
@@ -425,8 +408,7 @@ impl CrateDefMap {
                             Path { segments: path.segments[i..].to_vec(), kind: PathKind::Self_ };
                         log::debug!("resolving {:?} in other crate", path);
                         let defp_map = db.crate_def_map(module.krate);
-                        let (def, s) =
-                            defp_map.resolve_path_with_macro(db, module.module_id, &path);
+                        let (def, s) = defp_map.resolve_path(db, module.module_id, &path);
                         return ResolvePathResult::with(
                             def,
                             ReachedFixedPoint::Yes,
@@ -434,8 +416,9 @@ impl CrateDefMap {
                         );
                     }
 
-                    match self[module.module_id].scope.get_item_or_macro(&segment.name) {
-                        Some(res) => res,
+                    // Since it is a quantified path here, it should not contains legacy macros
+                    match self[module.module_id].scope.get(&segment.name) {
+                        Some(res) => res.def,
                         _ => {
                             log::debug!("path segment {:?} not found", segment.name);
                             return ResolvePathResult::empty(ReachedFixedPoint::No);
@@ -446,10 +429,10 @@ impl CrateDefMap {
                     // enum variant
                     tested_by!(can_import_enum_variant);
                     match e.variant(db, &segment.name) {
-                        Some(variant) => Either::A(PerNs::both(variant.into(), variant.into())),
+                        Some(variant) => PerNs::both(variant.into(), variant.into()),
                         None => {
                             return ResolvePathResult::with(
-                                Either::A(PerNs::types((*e).into())),
+                                PerNs::types((*e).into()),
                                 ReachedFixedPoint::Yes,
                                 Some(i),
                             );
@@ -466,7 +449,7 @@ impl CrateDefMap {
                     );
 
                     return ResolvePathResult::with(
-                        Either::A(PerNs::types(*s)),
+                        PerNs::types(*s),
                         ReachedFixedPoint::Yes,
                         Some(i),
                     );
@@ -476,14 +459,12 @@ impl CrateDefMap {
         ResolvePathResult::with(curr_per_ns, ReachedFixedPoint::Yes, None)
     }
 
-    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> ItemOrMacro {
-        let from_crate_root = self[self.root]
-            .scope
-            .get_item_or_macro(name)
-            .unwrap_or_else(|| Either::A(PerNs::none()));
+    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> PerNs<ModuleDef> {
+        let from_crate_root =
+            self[self.root].scope.get(name).map_or_else(PerNs::none, |res| res.def);
         let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
 
-        or(from_crate_root, Either::A(from_extern_prelude))
+        from_crate_root.or(from_extern_prelude)
     }
 
     pub(crate) fn resolve_name_in_module(
@@ -492,47 +473,38 @@ impl CrateDefMap {
         module: CrateModuleId,
         name: &Name,
     ) -> PerNs<ModuleDef> {
-        self.resolve_name_in_module_with_macro(db, module, name).a().unwrap_or_else(PerNs::none)
-    }
-
-    fn resolve_name_in_module_with_macro(
-        &self,
-        db: &impl DefDatabase,
-        module: CrateModuleId,
-        name: &Name,
-    ) -> ItemOrMacro {
         // Resolve in:
-        //  - legacy scope
+        //  - 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(|| Either::A(PerNs::none()), Either::B);
-        let from_scope =
-            self[module].scope.get_item_or_macro(name).unwrap_or_else(|| Either::A(PerNs::none()));
+        let from_legacy_macro =
+            self[module].scope.get_legacy_macro(name).map_or_else(PerNs::none, PerNs::macros);
+        let from_scope = self[module].scope.get(name).map_or_else(PerNs::none, |res| res.def);
         let from_extern_prelude =
             self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it));
         let from_prelude = self.resolve_in_prelude(db, name);
 
-        or(from_legacy_macro, or(from_scope, or(Either::A(from_extern_prelude), from_prelude)))
+        from_legacy_macro.or(from_scope).or(from_extern_prelude).or(from_prelude)
     }
 
     fn resolve_name_in_extern_prelude(&self, name: &Name) -> PerNs<ModuleDef> {
         self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it))
     }
 
-    fn resolve_in_prelude(&self, db: &impl DefDatabase, name: &Name) -> ItemOrMacro {
+    fn resolve_in_prelude(&self, db: &impl DefDatabase, name: &Name) -> PerNs<ModuleDef> {
         if let Some(prelude) = self.prelude {
-            let resolution = if prelude.krate == self.krate {
-                self[prelude.module_id].scope.get_item_or_macro(name)
+            let keep;
+            let def_map = if prelude.krate == self.krate {
+                self
             } else {
-                db.crate_def_map(prelude.krate)[prelude.module_id].scope.get_item_or_macro(name)
+                // Extend lifetime
+                keep = db.crate_def_map(prelude.krate);
+                &keep
             };
-            resolution.unwrap_or_else(|| Either::A(PerNs::none()))
+            def_map[prelude.module_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
         } else {
-            Either::A(PerNs::none())
+            PerNs::none()
         }
     }
 }
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index 09cda7656..03fbbd33f 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -5,14 +5,13 @@ use test_utils::tested_by;
 
 use crate::{
     db::DefDatabase,
-    either::Either,
     ids::{AstItemDef, LocationCtx, MacroCallId, MacroCallLoc, MacroDefId, MacroFileKind},
     name::MACRO_RULES,
     nameres::{
         diagnostics::DefDiagnostic,
         mod_resolution::{resolve_submodule, ParentModule},
-        raw, CrateDefMap, CrateModuleId, ItemOrMacro, ModuleData, ModuleDef, PerNs,
-        ReachedFixedPoint, Resolution, ResolveMode,
+        raw, Crate, CrateDefMap, CrateModuleId, ModuleData, ModuleDef, PerNs, ReachedFixedPoint,
+        Resolution, ResolveMode,
     },
     AstId, Const, Enum, Function, HirFileId, MacroDef, Module, Name, Path, PathKind, Static,
     Struct, Trait, TypeAlias, Union,
@@ -123,30 +122,51 @@ where
         let unresolved_imports = std::mem::replace(&mut self.unresolved_imports, Vec::new());
         // show unresolved imports in completion, etc
         for (module_id, import, import_data) in unresolved_imports {
-            self.record_resolved_import(module_id, Either::A(PerNs::none()), import, &import_data)
+            self.record_resolved_import(module_id, PerNs::none(), import, &import_data)
         }
     }
 
+    /// 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, bacause 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: CrateModuleId,
         name: Name,
-        macro_id: MacroDefId,
+        macro_: MacroDef,
         export: bool,
     ) {
-        let def = Either::B(MacroDef { id: macro_id });
+        // 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, None, &[(name.clone(), def.clone())]);
-
-            // Exported macros are collected in crate level ready for
-            // glob import with `#[macro_use]`.
-            self.def_map.exported_macros.insert(name.clone(), macro_id);
+            self.update(self.def_map.root, None, &[(name.clone(), Resolution::from_macro(macro_))]);
         }
-        self.update(module_id, None, &[(name.clone(), def)]);
-        self.define_legacy_macro(module_id, name.clone(), macro_id);
     }
 
     /// Define a legacy textual scoped macro in module
@@ -156,14 +176,12 @@ where
     /// the definition of current module.
     /// And also, `macro_use` on a module will import all legacy macros visable inside to
     /// current legacy scope, with possible shadowing.
-    fn define_legacy_macro(&mut self, module_id: CrateModuleId, name: Name, macro_id: MacroDefId) {
+    fn define_legacy_macro(&mut self, module_id: CrateModuleId, name: Name, macro_: MacroDef) {
         // Always shadowing
-        self.def_map.modules[module_id].scope.legacy_macros.insert(name, MacroDef { id: macro_id });
+        self.def_map.modules[module_id].scope.legacy_macros.insert(name, macro_);
     }
 
     /// Import macros from `#[macro_use] extern crate`.
-    ///
-    /// They are non-scoped, and will only be inserted into mutable `global_macro_scope`.
     fn import_macros_from_extern_crate(
         &mut self,
         current_module_id: CrateModuleId,
@@ -184,14 +202,20 @@ where
 
         if let Some(ModuleDef::Module(m)) = res.take_types() {
             tested_by!(macro_rules_from_other_crates_are_visible_with_macro_use);
-            self.import_all_macros_exported(current_module_id, m);
+            self.import_all_macros_exported(current_module_id, m.krate);
         }
     }
 
-    fn import_all_macros_exported(&mut self, current_module_id: CrateModuleId, module: Module) {
-        let item_map = self.db.crate_def_map(module.krate);
-        for (name, &macro_id) in &item_map.exported_macros {
-            self.define_legacy_macro(current_module_id, name.clone(), macro_id);
+    /// 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: CrateModuleId, krate: Crate) {
+        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);
         }
     }
 
@@ -219,7 +243,7 @@ where
         &self,
         module_id: CrateModuleId,
         import: &raw::ImportData,
-    ) -> (ItemOrMacro, ReachedFixedPoint) {
+    ) -> (PerNs<ModuleDef>, ReachedFixedPoint) {
         log::debug!("resolving import: {:?} ({:?})", import, self.def_map.edition);
         if import.is_extern_crate {
             let res = self.def_map.resolve_name_in_extern_prelude(
@@ -228,7 +252,7 @@ where
                     .as_ident()
                     .expect("extern crate should have been desugared to one-element path"),
             );
-            (Either::A(res), ReachedFixedPoint::Yes)
+            (res, ReachedFixedPoint::Yes)
         } else {
             let res = self.def_map.resolve_path_fp_with_macro(
                 self.db,
@@ -244,13 +268,13 @@ where
     fn record_resolved_import(
         &mut self,
         module_id: CrateModuleId,
-        def: ItemOrMacro,
+        def: PerNs<ModuleDef>,
         import_id: raw::ImportId,
         import: &raw::ImportData,
     ) {
         if import.is_glob {
             log::debug!("glob import: {:?}", import);
-            match def.a().and_then(|item| item.take_types()) {
+            match def.take_types() {
                 Some(ModuleDef::Module(m)) => {
                     if import.is_prelude {
                         tested_by!(std_prelude);
@@ -260,30 +284,29 @@ where
                         // 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.module_id].scope;
+
+                        // Module scoped macros is included
                         let items = scope
                             .items
                             .iter()
-                            .map(|(name, res)| (name.clone(), Either::A(res.clone())));
-                        let macros =
-                            scope.macros.iter().map(|(name, res)| (name.clone(), Either::B(*res)));
+                            .map(|(name, res)| (name.clone(), res.clone()))
+                            .collect::<Vec<_>>();
 
-                        let all = items.chain(macros).collect::<Vec<_>>();
-                        self.update(module_id, Some(import_id), &all);
+                        self.update(module_id, Some(import_id), &items);
                     } 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.module_id].scope;
+
+                        // Module scoped macros is included
                         let items = scope
                             .items
                             .iter()
-                            .map(|(name, res)| (name.clone(), Either::A(res.clone())));
-                        let macros =
-                            scope.macros.iter().map(|(name, res)| (name.clone(), Either::B(*res)));
+                            .map(|(name, res)| (name.clone(), res.clone()))
+                            .collect::<Vec<_>>();
 
-                        let all = items.chain(macros).collect::<Vec<_>>();
-
-                        self.update(module_id, Some(import_id), &all);
+                        self.update(module_id, Some(import_id), &items);
                         // record the glob import in case we add further items
                         self.glob_imports
                             .entry(m.module_id)
@@ -303,7 +326,7 @@ where
                                 import: Some(import_id),
                             };
                             let name = variant.name(self.db)?;
-                            Some((name, Either::A(res)))
+                            Some((name, res))
                         })
                         .collect::<Vec<_>>();
                     self.update(module_id, Some(import_id), &resolutions);
@@ -323,18 +346,12 @@ where
 
                     // 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) = def.a().and_then(|item| item.take_types()) {
+                        if let Some(def) = def.take_types() {
                             self.def_map.extern_prelude.insert(name.clone(), def);
                         }
                     }
 
-                    let resolution = match def {
-                        Either::A(item) => {
-                            Either::A(Resolution { def: item, import: Some(import_id) })
-                        }
-                        Either::B(macro_) => Either::B(macro_),
-                    };
-
+                    let resolution = Resolution { def, import: Some(import_id) };
                     self.update(module_id, Some(import_id), &[(name, resolution)]);
                 }
                 None => tested_by!(bogus_paths),
@@ -346,7 +363,7 @@ where
         &mut self,
         module_id: CrateModuleId,
         import: Option<raw::ImportId>,
-        resolutions: &[(Name, Either<Resolution, MacroDef>)],
+        resolutions: &[(Name, Resolution)],
     ) {
         self.update_recursive(module_id, import, resolutions, 0)
     }
@@ -355,7 +372,7 @@ where
         &mut self,
         module_id: CrateModuleId,
         import: Option<raw::ImportId>,
-        resolutions: &[(Name, Either<Resolution, MacroDef>)],
+        resolutions: &[(Name, Resolution)],
         depth: usize,
     ) {
         if depth > 100 {
@@ -365,35 +382,30 @@ where
         let module_items = &mut self.def_map.modules[module_id].scope;
         let mut changed = false;
         for (name, res) in resolutions {
-            match res {
-                // item
-                Either::A(res) => {
-                    let existing = module_items.items.entry(name.clone()).or_default();
-
-                    if existing.def.types.is_none() && res.def.types.is_some() {
-                        existing.def.types = res.def.types;
-                        existing.import = import.or(res.import);
-                        changed = true;
-                    }
-                    if existing.def.values.is_none() && res.def.values.is_some() {
-                        existing.def.values = res.def.values;
-                        existing.import = import.or(res.import);
-                        changed = true;
-                    }
+            let existing = module_items.items.entry(name.clone()).or_default();
 
-                    if existing.def.is_none()
-                        && res.def.is_none()
-                        && existing.import.is_none()
-                        && res.import.is_some()
-                    {
-                        existing.import = res.import;
-                    }
-                }
-                // macro
-                Either::B(res) => {
-                    // Always shadowing
-                    module_items.macros.insert(name.clone(), *res);
-                }
+            if existing.def.types.is_none() && res.def.types.is_some() {
+                existing.def.types = res.def.types;
+                existing.import = import.or(res.import);
+                changed = true;
+            }
+            if existing.def.values.is_none() && res.def.values.is_some() {
+                existing.def.values = res.def.values;
+                existing.import = import.or(res.import);
+                changed = true;
+            }
+            if existing.def.macros.is_none() && res.def.macros.is_some() {
+                existing.def.macros = res.def.macros;
+                existing.import = import.or(res.import);
+                changed = true;
+            }
+
+            if existing.def.is_none()
+                && res.def.is_none()
+                && existing.import.is_none()
+                && res.import.is_some()
+            {
+                existing.import = res.import;
             }
         }
 
@@ -425,7 +437,7 @@ where
                 path,
             );
 
-            if let Some(def) = resolved_res.resolved_def.b() {
+            if let Some(def) = resolved_res.resolved_def.get_macros() {
                 let call_id = MacroCallLoc { def: def.id, ast_id: *ast_id }.id(self.db);
                 resolved.push((*module_id, call_id, def.id));
                 res = ReachedFixedPoint::No;
@@ -528,7 +540,7 @@ where
         if let Some(prelude_module) = self.def_collector.def_map.prelude {
             if prelude_module.krate != self.def_collector.def_map.krate {
                 tested_by!(prelude_is_macro_use);
-                self.def_collector.import_all_macros_exported(self.module_id, prelude_module);
+                self.def_collector.import_all_macros_exported(self.module_id, prelude_module.krate);
             }
         }
 
@@ -636,7 +648,7 @@ where
             ),
             import: None,
         };
-        self.def_collector.update(self.module_id, None, &[(name, Either::A(resolution))]);
+        self.def_collector.update(self.module_id, None, &[(name, resolution)]);
         res
     }
 
@@ -667,7 +679,7 @@ where
             raw::DefKind::TypeAlias(ast_id) => PerNs::types(def!(TypeAlias, ast_id)),
         };
         let resolution = Resolution { def, import: None };
-        self.def_collector.update(self.module_id, None, &[(name, Either::A(resolution))])
+        self.def_collector.update(self.module_id, None, &[(name, resolution)])
     }
 
     fn collect_macro(&mut self, mac: &raw::MacroData) {
@@ -675,7 +687,8 @@ where
         if is_macro_rules(&mac.path) {
             if let Some(name) = &mac.name {
                 let macro_id = MacroDefId(mac.ast_id.with_file_id(self.file_id));
-                self.def_collector.define_macro(self.module_id, name.clone(), macro_id, mac.export)
+                let macro_ = MacroDef { id: macro_id };
+                self.def_collector.define_macro(self.module_id, name.clone(), macro_, mac.export);
             }
             return;
         }
@@ -706,7 +719,7 @@ where
     fn import_all_legacy_macros(&mut self, module_id: CrateModuleId) {
         let macros = self.def_collector.def_map[module_id].scope.legacy_macros.clone();
         for (name, macro_) in macros {
-            self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_.id);
+            self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_);
         }
     }
 }
@@ -758,7 +771,6 @@ mod tests {
                 root,
                 modules,
                 poison_macros: FxHashSet::default(),
-                exported_macros: FxHashMap::default(),
                 diagnostics: Vec::new(),
             }
         };
diff --git a/crates/ra_hir/src/nameres/per_ns.rs b/crates/ra_hir/src/nameres/per_ns.rs
index c40a3ff9d..d07cc08f4 100644
--- a/crates/ra_hir/src/nameres/per_ns.rs
+++ b/crates/ra_hir/src/nameres/per_ns.rs
@@ -1,78 +1,87 @@
+use crate::MacroDef;
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Namespace {
     Types,
     Values,
+    // Note that only type inference uses this enum, and it doesn't care about macros.
+    // Macro,
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct PerNs<T> {
     pub types: Option<T>,
     pub values: Option<T>,
+    /// Since macros has different type, many methods simply ignore it.
+    /// We can only use special method like `get_macros` to access it.
+    pub macros: Option<MacroDef>,
 }
 
 impl<T> Default for PerNs<T> {
     fn default() -> Self {
-        PerNs { types: None, values: None }
+        PerNs { types: None, values: None, macros: None }
     }
 }
 
 impl<T> PerNs<T> {
     pub fn none() -> PerNs<T> {
-        PerNs { types: None, values: None }
+        PerNs { types: None, values: None, macros: None }
     }
 
     pub fn values(t: T) -> PerNs<T> {
-        PerNs { types: None, values: Some(t) }
+        PerNs { types: None, values: Some(t), macros: None }
     }
 
     pub fn types(t: T) -> PerNs<T> {
-        PerNs { types: Some(t), values: None }
+        PerNs { types: Some(t), values: None, macros: None }
     }
 
     pub fn both(types: T, values: T) -> PerNs<T> {
-        PerNs { types: Some(types), values: Some(values) }
+        PerNs { types: Some(types), values: Some(values), macros: None }
     }
 
-    pub fn is_none(&self) -> bool {
-        self.types.is_none() && self.values.is_none()
+    pub fn macros(macro_: MacroDef) -> PerNs<T> {
+        PerNs { types: None, values: None, macros: Some(macro_) }
     }
 
-    pub fn is_both(&self) -> bool {
-        self.types.is_some() && self.values.is_some()
+    pub fn is_none(&self) -> bool {
+        self.types.is_none() && self.values.is_none() && self.macros.is_none()
     }
 
-    pub fn take(self, namespace: Namespace) -> Option<T> {
-        match namespace {
-            Namespace::Types => self.types,
-            Namespace::Values => self.values,
-        }
+    pub fn is_all(&self) -> bool {
+        self.types.is_some() && self.values.is_some() && self.macros.is_some()
     }
 
     pub fn take_types(self) -> Option<T> {
-        self.take(Namespace::Types)
+        self.types
     }
 
     pub fn take_values(self) -> Option<T> {
-        self.take(Namespace::Values)
+        self.values
     }
 
-    pub fn get(&self, namespace: Namespace) -> Option<&T> {
-        self.as_ref().take(namespace)
+    pub fn get_macros(&self) -> Option<MacroDef> {
+        self.macros
     }
 
-    pub fn as_ref(&self) -> PerNs<&T> {
-        PerNs { types: self.types.as_ref(), values: self.values.as_ref() }
+    pub fn only_macros(&self) -> PerNs<T> {
+        PerNs { types: None, values: None, macros: self.macros }
     }
 
-    pub fn or(self, other: PerNs<T>) -> PerNs<T> {
-        PerNs { types: self.types.or(other.types), values: self.values.or(other.values) }
+    pub fn as_ref(&self) -> PerNs<&T> {
+        PerNs { types: self.types.as_ref(), values: self.values.as_ref(), macros: self.macros }
     }
 
-    pub fn and_then<U>(self, f: impl Fn(T) -> Option<U>) -> PerNs<U> {
-        PerNs { types: self.types.and_then(&f), values: self.values.and_then(&f) }
+    pub fn or(self, other: PerNs<T>) -> PerNs<T> {
+        PerNs {
+            types: self.types.or(other.types),
+            values: self.values.or(other.values),
+            macros: self.macros.or(other.macros),
+        }
     }
 
+    /// Map types and values. Leave macros unchanged.
     pub fn map<U>(self, f: impl Fn(T) -> U) -> PerNs<U> {
-        PerNs { types: self.types.map(&f), values: self.values.map(&f) }
+        PerNs { types: self.types.map(&f), values: self.values.map(&f), macros: self.macros }
     }
 }
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index 4ff897ca5..bc4b47b70 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -12,8 +12,7 @@ use test_utils::covers;
 
 use crate::{
     mock::{CrateGraphFixture, MockDatabase},
-    nameres::Resolution,
-    Crate, Either,
+    Crate,
 };
 
 use super::*;
@@ -37,35 +36,38 @@ fn render_crate_def_map(map: &CrateDefMap) -> String {
         *buf += path;
         *buf += "\n";
 
-        let items = map.modules[module].scope.items.iter().map(|(name, it)| (name, Either::A(it)));
-        let macros = map.modules[module].scope.macros.iter().map(|(name, m)| (name, Either::B(m)));
-        let mut entries = items.chain(macros).collect::<Vec<_>>();
-
+        let mut entries = map.modules[module]
+            .scope
+            .items
+            .iter()
+            .map(|(name, res)| (name, res.def))
+            .collect::<Vec<_>>();
         entries.sort_by_key(|(name, _)| *name);
+
         for (name, res) in entries {
-            match res {
-                Either::A(it) => {
-                    *buf += &format!("{}: {}\n", name, dump_resolution(it));
-                }
-                Either::B(_) => {
-                    *buf += &format!("{}: m\n", name);
-                }
+            *buf += &format!("{}:", name);
+
+            if res.types.is_some() {
+                *buf += " t";
+            }
+            if res.values.is_some() {
+                *buf += " v";
+            }
+            if res.macros.is_some() {
+                *buf += " m";
+            }
+            if res.is_none() {
+                *buf += " _";
             }
+
+            *buf += "\n";
         }
+
         for (name, child) in map.modules[module].children.iter() {
             let path = path.to_string() + &format!("::{}", name);
             go(buf, map, &path, *child);
         }
     }
-
-    fn dump_resolution(resolution: &Resolution) -> &'static str {
-        match (resolution.def.types.is_some(), resolution.def.values.is_some()) {
-            (true, true) => "t v",
-            (true, false) => "t",
-            (false, true) => "v",
-            (false, false) => "_",
-        }
-    }
 }
 
 fn def_map(fixtute: &str) -> String {
diff --git a/crates/ra_hir/src/nameres/tests/macros.rs b/crates/ra_hir/src/nameres/tests/macros.rs
index ebc4d6890..20ee63c67 100644
--- a/crates/ra_hir/src/nameres/tests/macros.rs
+++ b/crates/ra_hir/src/nameres/tests/macros.rs
@@ -21,7 +21,6 @@ fn macro_rules_are_globally_visible() {
    ⋮crate
    ⋮Foo: t v
    ⋮nested: t
-   ⋮structs: m
    ⋮
    ⋮crate::nested
    ⋮Bar: t v
@@ -47,7 +46,6 @@ fn macro_rules_can_define_modules() {
     );
     assert_snapshot!(map, @r###"
    ⋮crate
-   ⋮m: m
    ⋮n1: t
    ⋮
    ⋮crate::n1
@@ -133,7 +131,6 @@ fn unexpanded_macro_should_expand_by_fixedpoint_loop() {
    ⋮crate
    ⋮Foo: t v
    ⋮bar: m
-   ⋮baz: m
    ⋮foo: m
     "###);
 }
@@ -271,7 +268,6 @@ fn prelude_cycle() {
         ⋮prelude: t
         ⋮
         ⋮crate::prelude
-        ⋮declare_mod: m
     "###);
 }
 
@@ -345,7 +341,6 @@ fn plain_macros_are_legacy_textual_scoped() {
    ⋮Ok: t v
    ⋮OkAfter: t v
    ⋮OkShadowStop: t v
-   ⋮foo: m
    ⋮m1: t
    ⋮m2: t
    ⋮m3: t
@@ -354,28 +349,132 @@ fn plain_macros_are_legacy_textual_scoped() {
    ⋮ok_double_macro_use_shadow: v
    ⋮
    ⋮crate::m7
-   ⋮baz: m
    ⋮
    ⋮crate::m1
-   ⋮bar: m
    ⋮
    ⋮crate::m5
    ⋮m6: t
    ⋮
    ⋮crate::m5::m6
-   ⋮foo: m
    ⋮
    ⋮crate::m2
    ⋮
    ⋮crate::m3
    ⋮OkAfterInside: t v
    ⋮OkMacroUse: t v
-   ⋮foo: m
    ⋮m4: t
    ⋮ok_shadow: v
    ⋮
    ⋮crate::m3::m4
-   ⋮bar: m
    ⋮ok_shadow_deep: v
     "###);
 }
+
+#[test]
+fn type_value_macro_live_in_different_scopes() {
+    let map = def_map(
+        "
+        //- /main.rs
+        #[macro_export]
+        macro_rules! foo {
+            ($x:ident) => { type $x = (); }
+        }
+
+        foo!(foo);
+        use foo as bar;
+
+        use self::foo as baz;
+        fn baz() {}
+        ",
+    );
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮bar: t m
+        ⋮baz: t v m
+        ⋮foo: t m
+    "###);
+}
+
+#[test]
+fn macro_use_can_be_aliased() {
+    let map = def_map_with_crate_graph(
+        "
+        //- /main.rs
+        #[macro_use]
+        extern crate foo;
+
+        foo!(Direct);
+        bar!(Alias);
+
+        //- /lib.rs
+        use crate::foo as bar;
+
+        mod m {
+            #[macro_export]
+            macro_rules! foo {
+                ($x:ident) => { struct $x; }
+            }
+        }
+        ",
+        crate_graph! {
+            "main": ("/main.rs", ["foo"]),
+            "foo": ("/lib.rs", []),
+        },
+    );
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Alias: t v
+        ⋮Direct: t v
+        ⋮foo: t
+    "###);
+}
+
+#[test]
+fn path_quantified_macros() {
+    let map = def_map(
+        "
+        //- /main.rs
+        macro_rules! foo {
+            ($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;
+        }
+        ",
+    );
+    assert_snapshot!(map, @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: _
+    "###);
+}
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index ef75308f6..d9bdd0e22 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -6,7 +6,6 @@ use rustc_hash::{FxHashMap, FxHashSet};
 use crate::{
     code_model::Crate,
     db::HirDatabase,
-    either::Either,
     expr::{
         scope::{ExprScopes, ScopeId},
         PatId,
@@ -126,7 +125,7 @@ impl Resolver {
         let mut resolution = PerNs::none();
         for scope in self.scopes.iter().rev() {
             resolution = resolution.or(scope.resolve_name(db, name));
-            if resolution.is_both() {
+            if resolution.is_all() {
                 return resolution;
             }
         }
@@ -139,10 +138,7 @@ impl Resolver {
         path: &Path,
     ) -> Option<MacroDef> {
         let (item_map, module) = self.module()?;
-        match item_map.resolve_path_with_macro(db, module, path) {
-            (Either::B(macro_def), None) => Some(macro_def),
-            _ => None,
-        }
+        item_map.resolve_path(db, module, path).0.get_macros()
     }
 
     /// Returns the resolved path segments
@@ -191,6 +187,9 @@ impl Resolver {
                 if current.values.is_none() {
                     current.values = res.values;
                 }
+                if current.macros.is_none() {
+                    current.macros = res.macros;
+                }
             });
         }
         names
@@ -313,6 +312,9 @@ impl Scope {
                 m.crate_def_map[m.module_id].scope.entries().for_each(|(name, res)| {
                     f(name.clone(), res.def.map(Resolution::Def));
                 });
+                m.crate_def_map[m.module_id].scope.legacy_macros().for_each(|(name, macro_)| {
+                    f(name.clone(), PerNs::macros(macro_));
+                });
                 m.crate_def_map.extern_prelude().iter().for_each(|(name, def)| {
                     f(name.clone(), PerNs::types(Resolution::Def(*def)));
                 });
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 2c7d94bce..c60e72abf 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -2838,6 +2838,64 @@ fn main() {
     );
 }
 
+#[test]
+fn infer_path_quantified_macros_expanded() {
+    assert_snapshot!(
+        infer(r#"
+#[macro_export]
+macro_rules! foo {
+    () => { 42i32 }
+}
+
+mod m {
+    pub use super::foo as bar;
+}
+
+fn main() {
+    let x = crate::foo!();
+    let y = m::bar!();
+}
+"#),
+        @r###"
+    ![0; 5) '42i32': i32
+    ![0; 5) '42i32': i32
+    [111; 164) '{     ...!(); }': ()
+    [121; 122) 'x': i32
+    [148; 149) 'y': i32
+    "###
+    );
+}
+
+#[test]
+fn infer_type_value_macro_having_same_name() {
+    assert_snapshot!(
+        infer(r#"
+#[macro_export]
+macro_rules! foo {
+    () => {
+        mod foo {
+            pub use super::foo;
+        }
+    };
+    ($x:tt) => {
+        $x
+    };
+}
+
+foo!();
+
+fn foo() {
+    let foo = foo::foo!(42i32);
+}
+"#),
+        @r###"
+    ![0; 5) '42i32': i32
+    [171; 206) '{     ...32); }': ()
+    [181; 184) 'foo': i32
+    "###
+    );
+}
+
 #[ignore]
 #[test]
 fn method_resolution_trait_before_autoref() {