libstd: changes to in response to #5656

src/libstd/future.rs

@@ -55,7 +55,7 @@ pub impl<A:Copy> Future<A> {
 }
 
 pub impl<A> Future<A> {
-
+    #[cfg(stage0)]
     fn get_ref(&self) -> &'self A {
         /*!
         * Executes the future's closure and then returns a borrowed
@@ -80,6 +80,34 @@ pub impl<A> Future<A> {
             }
         }
     }
+
+    #[cfg(stage1)]
+    #[cfg(stage2)]
+    #[cfg(stage3)]
+    fn get_ref<'a>(&'a self) -> &'a A {
+        /*!
+        * Executes the future's closure and then returns a borrowed
+        * pointer to the result.  The borrowed pointer lasts as long as
+        * the future.
+        */
+        unsafe {
+            match self.state {
+                Forced(ref mut v) => { return cast::transmute(v); }
+                Evaluating => fail!(~"Recursive forcing of future!"),
+                Pending(_) => {}
+            }
+
+            let mut state = Evaluating;
+            self.state <-> state;
+            match state {
+                Forced(_) | Evaluating => fail!(~"Logic error."),
+                Pending(f) => {
+                    self.state = Forced(f());
+                    self.get_ref()
+                }
+            }
+        }
+    }
 }
 
 pub fn from_value<A>(val: A) -> Future<A> {