associated_type.diff

---
 src/libcore/iter/mod.rs | 52 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index f1a3b8a..e2b9dd5 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -301,6 +301,7 @@
 
 use clone::Clone;
 use cmp;
+use default::Default;
 use fmt;
 use iter_private::TrustedRandomAccess;
 use ops::FnMut;
@@ -606,8 +607,7 @@ impl<A, B> DoubleEndedIterator for Chain<A, B> where
 pub struct Zip<A, B> {
     a: A,
     b: B,
-    index: usize,
-    len: usize,
+    spec: <(A, B) as ZipImplData>::Data,
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -649,6 +649,17 @@ trait ZipImpl<A, B> {
               B: DoubleEndedIterator + ExactSizeIterator;
 }
 
+// Zip specialization data members
+#[doc(hidden)]
+trait ZipImplData {
+    type Data: Clone + Default + fmt::Debug;
+}
+
+#[doc(hidden)]
+impl<T> ZipImplData for T {
+    default type Data = ();
+}
+
 // General Zip impl
 #[doc(hidden)]
 impl<A, B> ZipImpl<A, B> for Zip<A, B>
@@ -659,8 +670,7 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         Zip {
             a: a,
             b: b,
-            index: 0, // not used in general case
-            len: 0,
+            spec: Default::default(), // unused
         }
     }
 
@@ -714,6 +724,20 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
 }
 
 #[doc(hidden)]
+#[derive(Default, Debug, Clone)]
+struct ZipImplFields {
+    index: usize,
+    len: usize,
+}
+
+#[doc(hidden)]
+impl<A, B> ZipImplData for (A, B)
+    where A: TrustedRandomAccess, B: TrustedRandomAccess
+{
+    type Data = ZipImplFields;
+}
+
+#[doc(hidden)]
 impl<A, B> ZipImpl<A, B> for Zip<A, B>
     where A: TrustedRandomAccess, B: TrustedRandomAccess
 {
@@ -722,16 +746,18 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         Zip {
             a: a,
             b: b,
-            index: 0,
-            len: len,
+            spec: ZipImplFields {
+                index: 0,
+                len: len,
+            }
         }
     }
 
     #[inline]
     fn next(&mut self) -> Option<(A::Item, B::Item)> {
-        if self.index < self.len {
-            let i = self.index;
-            self.index += 1;
+        if self.spec.index < self.spec.len {
+            let i = self.spec.index;
+            self.spec.index += 1;
             unsafe {
                 Some((self.a.get_unchecked(i), self.b.get_unchecked(i)))
             }
@@ -742,7 +768,7 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let len = self.len - self.index;
+        let len = self.spec.len - self.spec.index;
         (len, Some(len))
     }
 
@@ -751,9 +777,9 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         where A: DoubleEndedIterator + ExactSizeIterator,
               B: DoubleEndedIterator + ExactSizeIterator
     {
-        if self.index < self.len {
-            self.len -= 1;
-            let i = self.len;
+        if self.spec.index < self.spec.len {
+            self.spec.len -= 1;
+            let i = self.spec.len;
             unsafe {
                 Some((self.a.get_unchecked(i), self.b.get_unchecked(i)))
             }
-- 
2.8.0.rc3

compiler_error.rs

rustc: x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_typeck
src/librustc_mir/graphviz.rs:109:29: 109:52 error: borrowed value does not live long enough
src/librustc_mir/graphviz.rs:109     for (&target, label) in terminator.successors().iter().zip(labels) {
                                                             ^~~~~~~~~~~~~~~~~~~~~~~
src/librustc_mir/graphviz.rs:109:5: 111:6 note: reference must be valid for the destruction scope surrounding statement at 109:4...
src/librustc_mir/graphviz.rs:109     for (&target, label) in terminator.successors().iter().zip(labels) {
src/librustc_mir/graphviz.rs:110         writeln!(w, r#"    {} -> {} [label="{}"];"#, node(source), node(target), label)?;
src/librustc_mir/graphviz.rs:111     }
src/librustc_mir/graphviz.rs:109:5: 111:6 note: ...but borrowed value is only valid for the statement at 109:4
src/librustc_mir/graphviz.rs:109     for (&target, label) in terminator.successors().iter().zip(labels) {
src/librustc_mir/graphviz.rs:110         writeln!(w, r#"    {} -> {} [label="{}"];"#, node(source), node(target), label)?;
src/librustc_mir/graphviz.rs:111     }
src/librustc_mir/graphviz.rs:109:5: 111:6 help: consider using a `let` binding to increase its lifetime
src/librustc_mir/graphviz.rs:109     for (&target, label) in terminator.successors().iter().zip(labels) {
src/librustc_mir/graphviz.rs:110         writeln!(w, r#"    {} -> {} [label="{}"];"#, node(source), node(target), label)?;
src/librustc_mir/graphviz.rs:111     }
error: aborting due to previous error