From 68a74decb683929f59588e07636e44c40434d6bc Mon Sep 17 00:00:00 2001
From: Ryo Yoshida <low.ryoshida@gmail.com>
Date: Wed, 17 May 2023 17:45:44 +0900
Subject: [PATCH] Process `macro_use` prelude in semantic scope resolver

---
 crates/hir-def/src/find_path.rs              |  2 +-
 crates/hir-def/src/nameres.rs                |  8 ++++++--
 crates/hir-def/src/resolver.rs               |  5 ++++-
 crates/ide-completion/src/tests/flyimport.rs | 21 ++++++++++++++++++++
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/crates/hir-def/src/find_path.rs b/crates/hir-def/src/find_path.rs
index b401762255e..1e299fecc9d 100644
--- a/crates/hir-def/src/find_path.rs
+++ b/crates/hir-def/src/find_path.rs
@@ -183,7 +183,7 @@ fn find_path_for_module(
 
     // - if the item is the crate root of a dependency crate, return the name from the extern prelude
     let root_def_map = crate_root.def_map(db);
-    for (name, &def_id) in root_def_map.extern_prelude() {
+    for (name, def_id) in root_def_map.extern_prelude() {
         if module_id == def_id {
             let name = scope_name.unwrap_or_else(|| name.clone());
 
diff --git a/crates/hir-def/src/nameres.rs b/crates/hir-def/src/nameres.rs
index 39a56814ed8..176637f9d0d 100644
--- a/crates/hir-def/src/nameres.rs
+++ b/crates/hir-def/src/nameres.rs
@@ -355,8 +355,12 @@ pub(crate) fn prelude(&self) -> Option<ModuleId> {
         self.prelude
     }
 
-    pub(crate) fn extern_prelude(&self) -> impl Iterator<Item = (&Name, &ModuleId)> + '_ {
-        self.extern_prelude.iter()
+    pub(crate) fn extern_prelude(&self) -> impl Iterator<Item = (&Name, ModuleId)> + '_ {
+        self.extern_prelude.iter().map(|(name, def)| (name, *def))
+    }
+
+    pub(crate) fn macro_use_prelude(&self) -> impl Iterator<Item = (&Name, MacroId)> + '_ {
+        self.macro_use_prelude.iter().map(|(name, def)| (name, *def))
     }
 
     pub fn module_id(&self, local_id: LocalModuleId) -> ModuleId {
diff --git a/crates/hir-def/src/resolver.rs b/crates/hir-def/src/resolver.rs
index 4bec2b4dea4..afa3b33cc9f 100644
--- a/crates/hir-def/src/resolver.rs
+++ b/crates/hir-def/src/resolver.rs
@@ -461,7 +461,10 @@ pub fn names_in_scope(
                 res.add(name, ScopeDef::ModuleDef(ModuleDefId::MacroId(mac)));
             })
         });
-        def_map.extern_prelude().for_each(|(name, &def)| {
+        def_map.macro_use_prelude().for_each(|(name, def)| {
+            res.add(name, ScopeDef::ModuleDef(def.into()));
+        });
+        def_map.extern_prelude().for_each(|(name, def)| {
             res.add(name, ScopeDef::ModuleDef(ModuleDefId::ModuleId(def)));
         });
         BUILTIN_SCOPE.iter().for_each(|(name, &def)| {
diff --git a/crates/ide-completion/src/tests/flyimport.rs b/crates/ide-completion/src/tests/flyimport.rs
index d727320b514..8c038c0fbaa 100644
--- a/crates/ide-completion/src/tests/flyimport.rs
+++ b/crates/ide-completion/src/tests/flyimport.rs
@@ -1265,3 +1265,24 @@ macro_rules! define_struct {
         "#]],
     );
 }
+
+#[test]
+fn macro_use_prelude_is_in_scope() {
+    check(
+        r#"
+//- /main.rs crate:main deps:dep
+#[macro_use]
+extern crate dep;
+
+fn main() {
+    print$0
+}
+//- /lib.rs crate:dep
+#[macro_export]
+macro_rules! println {
+    () => {}
+}
+"#,
+        expect![""],
+    )
+}