Make `sum` and `product` inherent methods on `Iterator`

In addition to being nicer, this also allows you to use `sum` and `product` for
iterators yielding custom types aside from the standard integers.

Due to removing the `AdditiveIterator` and `MultiplicativeIterator` trait, this
is a breaking change.

[breaking-change]

2 files changed, 2 insertions, 4 deletions

diff --git a/src/libcollections/slice.rs b/src/libcollections/slice.rs
index ff923fb1906..8622b8cd935 100644
--- a/src/libcollections/slice.rs
+++ b/src/libcollections/slice.rs
@@ -85,7 +85,6 @@ use core::clone::Clone;
 use core::cmp::Ordering::{self, Greater, Less};
 use core::cmp::{self, Ord, PartialEq};
 use core::iter::Iterator;
-use core::iter::MultiplicativeIterator;
 use core::marker::Sized;
 use core::mem::size_of;
 use core::mem;
@@ -1182,7 +1181,7 @@ impl Iterator for ElementSwaps {
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
         // For a vector of size n, there are exactly n! permutations.
-        let n = (2..self.sdir.len() + 1).product();
+        let n: usize = (2..self.sdir.len() + 1).product();
         (n - self.swaps_made, Some(n - self.swaps_made))
     }
 }
diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index c22b6fb9286..c5de430ae8c 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -53,7 +53,6 @@ use self::RecompositionState::*;
 use self::DecompositionType::*;
 
 use core::clone::Clone;
-use core::iter::AdditiveIterator;
 use core::iter::{Iterator, Extend};
 use core::option::Option::{self, Some, None};
 use core::result::Result;
@@ -112,7 +111,7 @@ impl<S: AsRef<str>> SliceConcatExt<str, String> for [S] {
         // this is wrong without the guarantee that `self` is non-empty
         // `len` calculation may overflow but push_str but will check boundaries
         let len = sep.len() * (self.len() - 1)
-            + self.iter().map(|s| s.as_ref().len()).sum();
+            + self.iter().map(|s| s.as_ref().len()).sum::<usize>();
         let mut result = String::with_capacity(len);
         let mut first = true;