Fix concatenation of super mod paths

crates/hir_def/src/item_tree.rs

@@ -790,13 +790,25 @@ impl UseTree {
                     }
                     Some((prefix, ImportKind::Plain))
                 }
-                (Some(prefix), PathKind::Super(0)) => {
-                    // `some::path::self` == `some::path`
-                    if path.segments().is_empty() {
-                        Some((prefix, ImportKind::TypeOnly))
-                    } else {
-                        None
+                (Some(mut prefix), PathKind::Super(n))
+                    if *n > 0 && prefix.segments().is_empty() =>
+                {
+                    // `super::super` + `super::rest`
+                    match &mut prefix.kind {
+                        PathKind::Super(m) => {
+                            cov_mark::hit!(concat_super_mod_paths);
+                            *m += *n;
+                            for segment in path.segments() {
+                                prefix.push_segment(segment.clone());
                             }
+                            Some((prefix, ImportKind::Plain))
+                        }
+                        _ => None,
+                    }
+                }
+                (Some(prefix), PathKind::Super(0)) if path.segments().is_empty() => {
+                    // `some::path::self` == `some::path`
+                    Some((prefix, ImportKind::TypeOnly))
                 }
                 (Some(_), _) => None,
             }

crates/hir_def/src/nameres/tests.rs

@@ -890,3 +890,38 @@ pub struct Struct;
         "#]],
     );
 }
+
+#[test]
+fn braced_supers_in_use_tree() {
+    cov_mark::check!(concat_super_mod_paths);
+    check(
+        r#"
+mod some_module {
+    pub fn unknown_func() {}
+}
+
+mod other_module {
+    mod some_submodule {
+        use { super::{ super::unknown_func, }, };
+    }
+}
+
+use some_module::unknown_func;
+        "#,
+        expect![[r#"
+            crate
+            other_module: t
+            some_module: t
+            unknown_func: v
+
+            crate::some_module
+            unknown_func: v
+
+            crate::other_module
+            some_submodule: t
+
+            crate::other_module::some_submodule
+            unknown_func: v
+        "#]],
+    )
+}