Formatter::sign is &'static str

The contents were always UTF-8 anyway, and &str has an equivalent representation
to &[u8], so this should not affect performance while removing unsafety at
edges.

It may be worth exploring a further adjustment that stores a single byte
(instead of 16) as the contents are always "", "-", or "+".

2 files changed, 6 insertions, 6 deletions

diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index 973c2f2b915..3f2c9654706 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -1356,11 +1356,11 @@ impl<'a> Formatter<'a> {
             let mut align = old_align;
             if self.sign_aware_zero_pad() {
                 // a sign always goes first
-                let sign = unsafe { str::from_utf8_unchecked(formatted.sign) };
+                let sign = formatted.sign;
                 self.buf.write_str(sign)?;
 
                 // remove the sign from the formatted parts
-                formatted.sign = b"";
+                formatted.sign = "";
                 width = width.saturating_sub(sign.len());
                 align = rt::v1::Alignment::Right;
                 self.fill = '0';
@@ -1392,7 +1392,7 @@ impl<'a> Formatter<'a> {
         }
 
         if !formatted.sign.is_empty() {
-            write_bytes(self.buf, formatted.sign)?;
+            self.buf.write_str(formatted.sign)?;
         }
         for part in formatted.parts {
             match *part {
diff --git a/src/libcore/fmt/num.rs b/src/libcore/fmt/num.rs
index c187471fb5f..5dfd3a8ecdb 100644
--- a/src/libcore/fmt/num.rs
+++ b/src/libcore/fmt/num.rs
@@ -369,11 +369,11 @@ macro_rules! impl_Exp {
                 flt2dec::Part::Copy(exp_slice)
             ];
             let sign = if !is_nonnegative {
-                &b"-"[..]
+                "-"
             } else if f.sign_plus() {
-                &b"+"[..]
+                "+"
             } else {
-                &b""[..]
+                ""
             };
             let formatted = flt2dec::Formatted{sign, parts};
             f.pad_formatted_parts(&formatted)