extend the lifetime of borrowed resource get (#1406)

* make as_ptr pub

* fix

* extend get lifetime

* fix

* add a test

* fix

Author: chenyan2002

crates/rust/src/interface.rs

@@ -2735,7 +2735,7 @@ impl<'a> {camel}Borrow<'a>{{
     }}
 
     /// Gets access to the underlying `T` in this resource.
-    pub fn get<T: Guest{camel}>(&self) -> &T {{
+    pub fn get<T: Guest{camel}>(&self) -> &'a T {{
        let ptr = unsafe {{ &mut *self.as_ptr::<T>() }};
        ptr.as_ref().unwrap()
     }}

tests/runtime/resource-borrow/test.rs

@@ -10,11 +10,15 @@ pub struct MyThing {
     val: u32,
 }
 
+fn get_val<'a>(v: &ThingBorrow<'a>) -> &'a u32 {
+  &v.get::<MyThing>().val
+}
+
 impl Guest for Test {
     type Thing = MyThing;
 
     fn foo(v: ThingBorrow<'_>) -> u32 {
-        v.get::<MyThing>().val + 2
+        get_val(&v) + 2
     }
 }