From 69e0b10150a3a426e7796841156e788c3866b27c Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Thu, 13 May 2021 02:17:41 +0200
Subject: Return absolute paths in find_path if crate start is ambiguous

---
 crates/hir_def/src/find_path.rs                | 13 +++++++++++--
 crates/ide_assists/src/handlers/auto_import.rs | 26 ++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

(limited to 'crates')

diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs
index 858e88038..ee52794aa 100644
--- a/crates/hir_def/src/find_path.rs
+++ b/crates/hir_def/src/find_path.rs
@@ -5,10 +5,10 @@ use std::iter;
 use hir_expand::name::{known, AsName, Name};
 use rustc_hash::FxHashSet;
 
-use crate::nameres::DefMap;
 use crate::{
     db::DefDatabase,
     item_scope::ItemInNs,
+    nameres::DefMap,
     path::{ModPath, PathKind},
     visibility::Visibility,
     ModuleDefId, ModuleId,
@@ -134,7 +134,16 @@ fn find_path_inner(
     for (name, def_id) in root_def_map.extern_prelude() {
         if item == ItemInNs::Types(*def_id) {
             let name = scope_name.unwrap_or_else(|| name.clone());
-            return Some(ModPath::from_segments(PathKind::Plain, vec![name]));
+
+            let name_already_occupied_in_type_ns = def_map
+                .with_ancestor_maps(db, from.local_id, &mut |def_map, local_id| {
+                    def_map[local_id].scope.get(&name).take_types().filter(|&id| id != *def_id)
+                })
+                .is_some();
+            return Some(ModPath::from_segments(
+                if name_already_occupied_in_type_ns { PathKind::Abs } else { PathKind::Plain },
+                vec![name],
+            ));
         }
     }
 
diff --git a/crates/ide_assists/src/handlers/auto_import.rs b/crates/ide_assists/src/handlers/auto_import.rs
index a454a2af3..506cc292c 100644
--- a/crates/ide_assists/src/handlers/auto_import.rs
+++ b/crates/ide_assists/src/handlers/auto_import.rs
@@ -966,6 +966,32 @@ mod bar {
         println!("Hallo");
     }
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn uses_abs_path_with_extern_crate_clash() {
+        check_assist(
+            auto_import,
+            r#"
+//- /main.rs crate:main deps:foo
+mod foo {}
+
+const _: () = {
+    Foo$0
+};
+//- /foo.rs crate:foo
+pub struct Foo
+"#,
+            r#"
+use ::foo::Foo;
+
+mod foo {}
+
+const _: () = {
+    Foo
+};
 "#,
         );
     }
-- 
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