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, 4 insertions, 6 deletions

diff --git a/src/libstd/old_path/posix.rs b/src/libstd/old_path/posix.rs
index c517fab257f..af63be2aa9e 100644
--- a/src/libstd/old_path/posix.rs
+++ b/src/libstd/old_path/posix.rs
@@ -15,8 +15,7 @@ use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
 use old_io::Writer;
-use iter::{AdditiveIterator, Extend};
-use iter::{Iterator, Map};
+use iter::{Extend, Iterator, Map};
 use marker::Sized;
 use option::Option::{self, Some, None};
 use result::Result::{self, Ok, Err};
@@ -351,7 +350,7 @@ impl Path {
                         Some(vec![SEP_BYTE])
                     } else {
                         let n = if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum();
+                                comps.iter().map(|v| v.len()).sum::<usize>();
                         let mut v = Vec::with_capacity(n);
                         let mut it = comps.into_iter();
                         if !is_abs {
diff --git a/src/libstd/old_path/windows.rs b/src/libstd/old_path/windows.rs
index 0b88f368b39..65aad38a2b4 100644
--- a/src/libstd/old_path/windows.rs
+++ b/src/libstd/old_path/windows.rs
@@ -20,8 +20,7 @@ use cmp::{Ordering, Eq, Ord, PartialEq, PartialOrd};
 use fmt;
 use hash;
 use old_io::Writer;
-use iter::{AdditiveIterator, Extend};
-use iter::{Iterator, Map, repeat};
+use iter::{Extend, Iterator, Map, repeat};
 use mem;
 use option::Option::{self, Some, None};
 use result::Result::{self, Ok, Err};
@@ -785,7 +784,7 @@ impl Path {
                         let prefix_ = &s[..prefix_len(prefix)];
                         let n = prefix_.len() +
                                 if is_abs { comps.len() } else { comps.len() - 1} +
-                                comps.iter().map(|v| v.len()).sum();
+                                comps.iter().map(|v| v.len()).sum::<usize>();
                         let mut s = String::with_capacity(n);
                         match prefix {
                             Some(DiskPrefix) => {