From 31aad2528f53349e9a0601c756d3c9f86ca9154c Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Tue, 8 Jun 2021 22:14:30 +0200
Subject: [PATCH] Fix edge case for ImportGranularity guessing

---
 crates/ide_db/src/helpers/insert_use.rs       | 18 +++++++++++-------
 crates/ide_db/src/helpers/insert_use/tests.rs | 15 +++++++++++++++
 crates/syntax/src/ast/node_ext.rs             |  5 ++++-
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/crates/ide_db/src/helpers/insert_use.rs b/crates/ide_db/src/helpers/insert_use.rs
index aa61c5bcb4..10bbafe776 100644
--- a/crates/ide_db/src/helpers/insert_use.rs
+++ b/crates/ide_db/src/helpers/insert_use.rs
@@ -120,15 +120,19 @@ impl ImportScope {
             if eq_visibility(prev_vis, curr_vis.clone()) && eq_attrs(prev_attrs, curr_attrs.clone())
             {
                 if let Some((prev_path, curr_path)) = prev.path().zip(curr.path()) {
-                    if let Some(_) = common_prefix(&prev_path, &curr_path) {
+                    if let Some((prev_prefix, _)) = common_prefix(&prev_path, &curr_path) {
                         if prev.use_tree_list().is_none() && curr.use_tree_list().is_none() {
-                            // Same prefix but no use tree lists so this has to be of item style.
-                            break ImportGranularityGuess::Item; // this overwrites CrateOrModule, technically the file doesn't adhere to anything here.
-                        } else {
-                            // Same prefix with item tree lists, has to be module style as it
-                            // can't be crate style since the trees wouldn't share a prefix then.
-                            break ImportGranularityGuess::Module;
+                            let prefix_c = prev_prefix.qualifiers().count();
+                            let curr_c = curr_path.qualifiers().count() - prefix_c;
+                            let prev_c = prev_path.qualifiers().count() - prefix_c;
+                            if curr_c <= 1 || prev_c <= 1 {
+                                // Same prefix but no use tree lists so this has to be of item style.
+                                break ImportGranularityGuess::Item; // this overwrites CrateOrModule, technically the file doesn't adhere to anything here.
+                            }
                         }
+                        // Same prefix with item tree lists, has to be module style as it
+                        // can't be crate style since the trees wouldn't share a prefix then.
+                        break ImportGranularityGuess::Module;
                     }
                 }
             }
diff --git a/crates/ide_db/src/helpers/insert_use/tests.rs b/crates/ide_db/src/helpers/insert_use/tests.rs
index 78a2a87b38..70b11bf81f 100644
--- a/crates/ide_db/src/helpers/insert_use/tests.rs
+++ b/crates/ide_db/src/helpers/insert_use/tests.rs
@@ -660,6 +660,13 @@ fn guess_item() {
         r"
 use foo::bar::baz;
 use foo::bar::qux;
+",
+        ImportGranularityGuess::Item,
+    );
+    check_guess(
+        r"
+use foo::bar::Bar;
+use foo::baz;
 ",
         ImportGranularityGuess::Item,
     );
@@ -679,6 +686,14 @@ use foo::bar::{qux, quux};
         r"
 use foo::bar::baz;
 use foo::{baz::{qux, quux}, bar};
+",
+        ImportGranularityGuess::Module,
+    );
+    check_guess(
+        r"
+use foo::bar::Bar;
+use foo::baz::Baz;
+use foo::{Foo, Qux};
 ",
         ImportGranularityGuess::Module,
     );
diff --git a/crates/syntax/src/ast/node_ext.rs b/crates/syntax/src/ast/node_ext.rs
index 884fe0739d..a60bc5ad95 100644
--- a/crates/syntax/src/ast/node_ext.rs
+++ b/crates/syntax/src/ast/node_ext.rs
@@ -259,11 +259,14 @@ impl ast::Path {
     }
 
     pub fn segments(&self) -> impl Iterator<Item = ast::PathSegment> + Clone {
-        // cant make use of SyntaxNode::siblings, because the returned Iterator is not clone
         successors(self.first_segment(), |p| {
             p.parent_path().parent_path().and_then(|p| p.segment())
         })
     }
+
+    pub fn qualifiers(&self) -> impl Iterator<Item = ast::Path> + Clone {
+        successors(self.qualifier(), |p| p.qualifier())
+    }
 }
 impl ast::UseTree {
     pub fn is_simple_path(&self) -> bool {