fix(rust): qualify world-owned type paths in future/stream payload vtables

crates/rust/src/interface.rs

@@ -1887,6 +1887,11 @@ unsafe fn call_import(&mut self, _params: Self::ParamsLower, _results: *mut u8)
                 return format!("{path}::{name}");
             }
         }
+        // World-level aliases live at macro root. `path_to_root()` is
+        // `""` at root, `"super::super::"` in stream/future payload mode.
+        if let TypeOwner::World(_) = self.resolve.types[id].owner {
+            return format!("{}{name}", self.path_to_root());
+        }
         name
     }
 

crates/test/src/csharp.rs

@@ -48,6 +48,7 @@ impl LanguageMethods for Csharp {
                 | "async-resource-func.wit"
                 | "import-export-resource.wit"
                 | "issue-1433.wit"
+                | "issue-1598.wit"
                 | "named-fixed-length-list.wit"
                 | "map.wit"
         )

tests/codegen/issue-1598.wit

@@ -0,0 +1,14 @@
+//@ async = true
+
+package a:b;
+
+world w {
+    use t.{r};
+    export f: async func() -> future<result<r, string>>;
+}
+
+interface t {
+    record r {
+        x: u32,
+    }
+}