From 08253d5473348e2f3061e0c8d84c62de537a5821 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Mon, 25 Jan 2021 19:15:39 +0100
Subject: [PATCH] Traverse parent DefMap for `super` paths

---
 crates/hir_def/src/nameres/path_resolution.rs | 37 ++++++++++++++-----
 crates/hir_def/src/nameres/tests/block.rs     | 26 +++++++++++++
 2 files changed, 54 insertions(+), 9 deletions(-)

diff --git a/crates/hir_def/src/nameres/path_resolution.rs b/crates/hir_def/src/nameres/path_resolution.rs
index 8ce127ddea..419e465ed8 100644
--- a/crates/hir_def/src/nameres/path_resolution.rs
+++ b/crates/hir_def/src/nameres/path_resolution.rs
@@ -10,8 +10,6 @@
 //!
 //! `ReachedFixedPoint` signals about this.
 
-use std::iter::successors;
-
 use base_db::Edition;
 use hir_expand::name;
 use hir_expand::name::Name;
@@ -193,14 +191,35 @@ impl DefMap {
                 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(self.module_id(local_id).into(), Visibility::Public)
-                } else {
-                    log::debug!("super path in root module");
-                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                let mut module = original_module;
+                for i in 0..lvl {
+                    match self.modules[module].parent {
+                        Some(it) => module = it,
+                        None => match &self.block {
+                            Some(block) => {
+                                // Look up remaining path in parent `DefMap`
+                                let new_path = ModPath {
+                                    kind: PathKind::Super(lvl - i),
+                                    segments: path.segments.clone(),
+                                };
+                                log::debug!("`super` path: {} -> {} in parent map", path, new_path);
+                                return block.parent.resolve_path_fp_with_macro(
+                                    db,
+                                    mode,
+                                    block.parent_module,
+                                    &new_path,
+                                    shadow,
+                                );
+                            }
+                            None => {
+                                log::debug!("super path in root module");
+                                return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                            }
+                        },
+                    }
                 }
+
+                PerNs::types(self.module_id(module).into(), Visibility::Public)
             }
             PathKind::Abs => {
                 // 2018-style absolute path -- only extern prelude
diff --git a/crates/hir_def/src/nameres/tests/block.rs b/crates/hir_def/src/nameres/tests/block.rs
index 01d6326a79..470ca593e1 100644
--- a/crates/hir_def/src/nameres/tests/block.rs
+++ b/crates/hir_def/src/nameres/tests/block.rs
@@ -95,3 +95,29 @@ fn outer() {
         "#]],
     );
 }
+
+#[test]
+fn super_imports() {
+    check_at(
+        r#"
+mod module {
+    fn f() {
+        use super::Struct;
+        $0
+    }
+}
+
+struct Struct {}
+"#,
+        expect![[r#"
+            block scope
+            Struct: t
+            crate
+            Struct: t
+            module: t
+
+            crate::module
+            f: v
+        "#]],
+    );
+}