fix Boxed types

tests/test.rs

@@ -15,10 +15,37 @@ pub fn func_3() -> Result<(),Nothing> {
     Ok(())
 }
 
+fn func_4() -> Anything {
+    let a= std::io::Error::last_os_error();
+    Anything::from(a)
+}
+
+fn func_5() -> Result<(), Anything> {
+    fn func_5a() -> Result<(), Anything> {
+        fn func_5b() -> Result<(), Anything> {
+            fn func_5c() -> Result<(), Anything> {
+                fn func_5d() -> Result<(), Anything> {
+                    Err("Hello World")?;
+                    Ok(())
+                }
+                func_5d()?;
+                Ok(())
+            }
+            func_5c()?;
+            Ok(())
+        }
+        func_5b()?;
+        Ok(())
+    }
+    func_5a()?;
+    Ok(())
+}
 
 #[test]
 pub fn test() {
-    println!("{:?}", func_1().unwrap_err());
-    println!("{:?}", func_2().unwrap_err());
-    println!("{:?}", func_3().unwrap_err());
+    println!("func1: {:?}\n", func_1().unwrap_err());
+    println!("func2: {:?}\n", func_2().unwrap_err());
+    println!("func3: {:?}\n", func_3().unwrap_err());
+    println!("func4: {:?}\n", func_4());
+    println!("func5: {:?}\n", func_5().unwrap_err());
 }