core: unbox closures used in let bindings

src/libcore/fmt/float.rs

@@ -225,10 +225,10 @@ pub fn float_to_str_bytes_common<T: Float, U, F>(
         // cut off the one extra digit, and depending on its value
         // round the remaining ones.
         if limit_digits && dig == digit_count {
-            let ascii2value = |chr: u8| {
+            let ascii2value = |&: chr: u8| {
                 (chr as char).to_digit(radix).unwrap()
             };
-            let value2ascii = |val: uint| {
+            let value2ascii = |&: val: uint| {
                 char::from_digit(val, radix).unwrap() as u8
             };
 

src/libcore/fmt/mod.rs

@@ -398,7 +398,7 @@ impl<'a> Formatter<'a> {
         }
 
         // Writes the sign if it exists, and then the prefix if it was requested
-        let write_prefix = |f: &mut Formatter| {
+        let write_prefix = |&: f: &mut Formatter| {
             for c in sign.into_iter() {
                 let mut b = [0, ..4];
                 let n = c.encode_utf8(&mut b).unwrap_or(0);