Implement ? in catch expressions and add tests

src/test/run-pass/catch-expr.rs

@@ -29,4 +29,38 @@ pub fn main() {
     match catch {
         _ => {}
     };
+
+    let catch_err = do catch {
+        Err(22)?;
+        Ok(1)
+    };
+    assert_eq!(catch_err, Err(22));
+
+    let catch_okay: Result<i32, i32> = do catch {
+        if false { Err(25)?; }
+        Ok::<(), i32>(())?;
+        Ok(28)
+    };
+    assert_eq!(catch_okay, Ok(28));
+
+    let catch_from_loop: Result<i32, i32> = do catch {
+        for i in 0..10 {
+            if i < 5 { Ok::<i32, i32>(i)?; } else { Err(i)?; }
+        }
+        Ok(22)
+    };
+    assert_eq!(catch_from_loop, Err(5));
+
+    let cfg_init;
+    let _res: Result<(), ()> = do catch {
+        cfg_init = 5;
+        Ok(())
+    };
+    assert_eq!(cfg_init, 5);
+
+    let my_string = "test".to_string();
+    let res: Result<&str, ()> = do catch {
+        Ok(&my_string)
+    };
+    assert_eq!(res, Ok("test"));
 }