From 3322595e896e95c3e19ca33c854ad529f2ef3c19 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Mon, 1 Apr 2013 22:32:37 -0700
Subject: Reason about nested free variables that appear in a function
 signature.  In a nutshell, the idea is to (1) report an error if, for a
 region pointer `'a T`, the lifetime `'a` is longer than any lifetimes that
 appear in `T` (in other words, if a borrowed pointer outlives any portion of
 its contents) and then (2) use this to assume that in a function like
 `fn(self: &'a &'b T)`, the relationship `'a <= 'b` holds. This is needed for
 #5656.  Fixes #5728.

---
 src/libcore/cmp.rs   | 21 +++++++++++++++++++++
 src/libcore/str.rs   |  6 +++++-
 src/libcore/tuple.rs |  1 -
 3 files changed, 26 insertions(+), 2 deletions(-)

(limited to 'src/libcore')

diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs
index f96575aaf41..bd4832b6faf 100644
--- a/src/libcore/cmp.rs
+++ b/src/libcore/cmp.rs
@@ -116,6 +116,19 @@ totalord_impl!(i64)
 totalord_impl!(int)
 totalord_impl!(uint)
 
+pub fn cmp2<A:TotalOrd,B:TotalOrd>(
+    a1: &A, b1: &B,
+    a2: &A, b2: &B) -> Ordering
+{
+    //! Compares (a1, b1) against (a2, b2), where the a values are more significant.
+
+    match a1.cmp(a2) {
+        Less => Less,
+        Greater => Greater,
+        Equal => b1.cmp(b2)
+    }
+}
+
 /**
 * Trait for values that can be compared for a sort-order.
 *
@@ -193,6 +206,14 @@ mod test {
         assert_eq!(12.cmp(-5), Greater);
     }
 
+    #[test]
+    fn test_cmp2() {
+        assert_eq!(cmp2(1, 2, 3, 4), Less);
+        assert_eq!(cmp2(3, 2, 3, 4), Less);
+        assert_eq!(cmp2(5, 2, 3, 4), Greater);
+        assert_eq!(cmp2(5, 5, 5, 4), Greater);
+    }
+
     #[test]
     fn test_int_totaleq() {
         assert!(5.equals(&5));
diff --git a/src/libcore/str.rs b/src/libcore/str.rs
index f1605309fb4..8d15d6afbda 100644
--- a/src/libcore/str.rs
+++ b/src/libcore/str.rs
@@ -301,7 +301,11 @@ pub fn slice_shift_char<'a>(s: &'a str) -> (char, &'a str) {
 
 /// Prepend a char to a string
 pub fn unshift_char(s: &mut ~str, ch: char) {
-    *s = from_char(ch) + *s;
+    // This could be more efficient.
+    let mut new_str = ~"";
+    new_str.push_char(ch);
+    new_str.push_str(*s);
+    *s = new_str;
 }
 
 /**
diff --git a/src/libcore/tuple.rs b/src/libcore/tuple.rs
index 35b8496f6c5..8234129e254 100644
--- a/src/libcore/tuple.rs
+++ b/src/libcore/tuple.rs
@@ -161,7 +161,6 @@ impl<A:Ord> Ord for (A,) {
     fn gt(&self, other: &(A,)) -> bool { other.lt(&(*self))  }
 }
 
-
 #[cfg(notest)]
 impl<A:Eq,B:Eq> Eq for (A, B) {
     #[inline(always)]
-- 
cgit 1.4.1-3-g733a5