auto merge of #13615 : alexcrichton/rust/improve-demangling, r=brson

Previously, symbols with rust escape sequences (denoted with dollar signs)
weren't demangled if the escape sequence showed up in the middle. This alters
the printing loop to look through the entire string for dollar characters.

src/libstd/rt/backtrace.rs

@@ -109,7 +109,7 @@ fn demangle(writer: &mut Writer, s: &str) -> IoResult<()> {
             let i: uint = from_str(s.slice_to(s.len() - rest.len())).unwrap();
             s = rest.slice_from(i);
             rest = rest.slice_to(i);
-            loop {
+            while rest.len() > 0 {
                 if rest.starts_with("$") {
                     macro_rules! demangle(
                         ($($pat:expr => $demangled:expr),*) => ({
@@ -144,8 +144,12 @@ macro_rules! demangle(
                         "$x5d" => "]"
                     )
                 } else {
-                    try!(writer.write_str(rest));
-                    break;
+                    let idx = match rest.find('$') {
+                        None => rest.len(),
+                        Some(i) => i,
+                    };
+                    try!(writer.write_str(rest.slice_to(idx)));
+                    rest = rest.slice_from(idx);
                 }
             }
         }
@@ -774,4 +778,10 @@ fn demangle_dollars() {
         t!("_ZN8$UP$test4foobE", "~test::foob");
         t!("_ZN8$x20test4foobE", " test::foob");
     }
+
+    #[test]
+    fn demangle_many_dollars() {
+        t!("_ZN12test$x20test4foobE", "test test::foob");
+        t!("_ZN12test$UP$test4foobE", "test~test::foob");
+    }
 }