Implement Extend for Repeated

PiperOrigin-RevId: 620277895

rust/repeated.rs

@@ -446,6 +446,18 @@ where
     }
 }
 
+impl<'msg, 'view, T, ViewT> Extend<ViewT> for RepeatedMut<'msg, T>
+where
+    T: ProxiedInRepeated + ?Sized + 'view,
+    ViewT: Into<View<'view, T>>,
+{
+    fn extend<I: IntoIterator<Item = ViewT>>(&mut self, iter: I) {
+        for item in iter {
+            self.push(item.into());
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -492,4 +504,20 @@ mod tests {
             bool => [false, true, true, false],
         );
     }
+
+    #[test]
+    fn test_repeated_extend() {
+        let mut r = Repeated::<i32>::new();
+        r.as_mut().extend([0, 1]);
+        assert_that!(r.as_mut().iter().collect::<Vec<_>>(), elements_are![eq(0), eq(1)]);
+        let mut x = Repeated::<i32>::new();
+        x.as_mut().extend([2, 3]);
+
+        r.as_mut().extend(&x.as_mut());
+
+        assert_that!(
+            r.as_mut().iter().collect::<Vec<_>>(),
+            elements_are![eq(0), eq(1), eq(2), eq(3)]
+        );
+    }
 }