auto merge of #12158 : nikomatsakis/rust/issue-6801-borrowck-closures, r=pcwalton

I factored the commits by affected files, for the most part. The last 7 or 8 contain the meat of the PR. The rest are small changes to closures found in the codebase. Maybe interesting to read to see some of the impact of the rules.

r? @pcwalton

Fixes #6801

Author: bors

src/doc/guide-container.md

@@ -181,19 +181,25 @@ never call its underlying iterator again once `None` has been returned:
 ~~~
 let xs = [1,2,3,4,5];
 let mut calls = 0;
-let it = xs.iter().scan((), |_, x| {
-    calls += 1;
-    if *x < 3 { Some(x) } else { None }});
-// the iterator will only yield 1 and 2 before returning None
-// If we were to call it 5 times, calls would end up as 5, despite only 2 values
-// being yielded (and therefore 3 unique calls being made). The fuse() adaptor
-// can fix this.
-let mut it = it.fuse();
-it.next();
-it.next();
-it.next();
-it.next();
-it.next();
+
+{
+    let it = xs.iter().scan((), |_, x| {
+        calls += 1;
+        if *x < 3 { Some(x) } else { None }});
+        
+    // the iterator will only yield 1 and 2 before returning None
+    // If we were to call it 5 times, calls would end up as 5, despite
+    // only 2 values being yielded (and therefore 3 unique calls being
+    // made). The fuse() adaptor can fix this.
+    
+    let mut it = it.fuse();
+    it.next();
+    it.next();
+    it.next();
+    it.next();
+    it.next();
+}
+
 assert_eq!(calls, 3);
 ~~~
 

src/libgetopts/lib.rs

@@ -775,14 +775,13 @@ fn each_split_within<'a>(ss: &'a str, lim: uint, it: |&'a str| -> bool)
     let mut lim = lim;
 
     let mut cont = true;
-    let slice: || = || { cont = it(ss.slice(slice_start, last_end)) };
 
     // if the limit is larger than the string, lower it to save cycles
     if lim >= fake_i {
         lim = fake_i;
     }
 
-    let machine: |(uint, char)| -> bool = |(i, c)| {
+    let machine: |&mut bool, (uint, char)| -> bool = |cont, (i, c)| {
         let whitespace = if ::std::char::is_whitespace(c) { Ws }       else { Cr };
         let limit      = if (i - slice_start + 1) <= lim  { UnderLim } else { OverLim };
 
@@ -794,24 +793,49 @@ fn each_split_within<'a>(ss: &'a str, lim: uint, it: |&'a str| -> bool)
             (B, Cr, OverLim)  if (i - last_start + 1) > lim
                             => fail!("word starting with {} longer than limit!",
                                     ss.slice(last_start, i + 1)),
-            (B, Cr, OverLim)  => { slice(); slice_start = last_start; B }
-            (B, Ws, UnderLim) => { last_end = i; C }
-            (B, Ws, OverLim)  => { last_end = i; slice(); A }
-
-            (C, Cr, UnderLim) => { last_start = i; B }
-            (C, Cr, OverLim)  => { slice(); slice_start = i; last_start = i; last_end = i; B }
-            (C, Ws, OverLim)  => { slice(); A }
-            (C, Ws, UnderLim) => { C }
+            (B, Cr, OverLim)  => {
+                *cont = it(ss.slice(slice_start, last_end));
+                slice_start = last_start;
+                B
+            }
+            (B, Ws, UnderLim) => {
+                last_end = i;
+                C
+            }
+            (B, Ws, OverLim)  => {
+                last_end = i;
+                *cont = it(ss.slice(slice_start, last_end));
+                A
+            }
+
+            (C, Cr, UnderLim) => {
+                last_start = i;
+                B
+            }
+            (C, Cr, OverLim)  => {
+                *cont = it(ss.slice(slice_start, last_end));
+                slice_start = i;
+                last_start = i;
+                last_end = i;
+                B
+            }
+            (C, Ws, OverLim)  => {
+                *cont = it(ss.slice(slice_start, last_end));
+                A
+            }
+            (C, Ws, UnderLim) => {
+                C
+            }
         };
 
-        cont
+        *cont
     };
 
-    ss.char_indices().advance(|x| machine(x));
+    ss.char_indices().advance(|x| machine(&mut cont, x));
 
     // Let the automaton 'run out' by supplying trailing whitespace
     while cont && match state { B | C => true, A => false } {
-        machine((fake_i, ' '));
+        machine(&mut cont, (fake_i, ' '));
         fake_i += 1;
     }
     return cont;