Rename Iterator::len to count

This commit carries out the request from issue #14678:

> The method `Iterator::len()` is surprising, as all the other uses of
> `len()` do not consume the value. `len()` would make more sense to be
> called `count()`, but that would collide with the current
> `Iterator::count(|T| -> bool) -> unit` method. That method, however, is
> a bit redundant, and can be easily replaced with
> `iter.filter(|x| x < 5).count()`.
> After this change, we could then define the `len()` method
> on `iter::ExactSize`.

Closes #14678.

[breaking-change]

1 files changed, 7 insertions, 7 deletions

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index aa80a131811..6ca21262f51 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -1772,23 +1772,23 @@ mod tests {
         assert_eq!(v.pop(), Some(()));
         assert_eq!(v.pop(), None);
 
-        assert_eq!(v.iter().len(), 0);
+        assert_eq!(v.iter().count(), 0);
         v.push(());
-        assert_eq!(v.iter().len(), 1);
+        assert_eq!(v.iter().count(), 1);
         v.push(());
-        assert_eq!(v.iter().len(), 2);
+        assert_eq!(v.iter().count(), 2);
 
         for &() in v.iter() {}
 
-        assert_eq!(v.mut_iter().len(), 2);
+        assert_eq!(v.mut_iter().count(), 2);
         v.push(());
-        assert_eq!(v.mut_iter().len(), 3);
+        assert_eq!(v.mut_iter().count(), 3);
         v.push(());
-        assert_eq!(v.mut_iter().len(), 4);
+        assert_eq!(v.mut_iter().count(), 4);
 
         for &() in v.mut_iter() {}
         unsafe { v.set_len(0); }
-        assert_eq!(v.mut_iter().len(), 0);
+        assert_eq!(v.mut_iter().count(), 0);
     }
 
     #[test]