rust: qualify world-owned type paths so future/stream payload vtables resolve

Author: mattwilkinsonn

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/rust/tests/codegen.rs

@@ -235,3 +235,25 @@ mod method_chaining {
         enable_method_chaining: true
     });
 }
+
+// Regression for #1598: world-level `use t.{r};` inside
+// `future<result<r, _>>` used to emit unresolved bare `R` in vtable{N}.
+#[allow(unused, reason = "testing codegen, not functionality")]
+mod issue_1598_future_result_use {
+    wit_bindgen::generate!({
+        inline: r#"
+        package a:b;
+
+        world w {
+            use t.{r};
+            export f: func() -> future<result<r, string>>;
+        }
+
+        interface t {
+            record r {
+                x: u32,
+            }
+        }
+        "#,
+    });
+}