Update from deprecated mem::uninitialized to MaybeUninit

Author: dtolnay

src/color.rs

@@ -1,6 +1,8 @@
 #[cfg(feature = "serde")]
 use std::fmt;
 #[cfg(any(feature = "serde", feature = "lib-rustc-serialize"))]
+use std::mem::MaybeUninit;
+#[cfg(any(feature = "serde", feature = "lib-rustc-serialize"))]
 use std::{ptr, slice, str};
 
 #[cfg(feature = "lib-rustc-serialize")]
@@ -26,8 +28,9 @@ const HEX_LUT: &'static [u8] = b"\
 
 #[cfg(any(feature = "serde", feature = "lib-rustc-serialize"))]
 impl Color {
-    fn as_str<'a>(self, buf: &'a mut [u8; 6]) -> &'a str {
-        let buf_ptr = buf.as_mut_ptr();
+    fn as_str(self, buf: &mut MaybeUninit<[u8; 6]>) -> &str {
+        let buf_len = 6;
+        let buf_ptr = buf.as_mut_ptr() as *mut u8;
         let lut_ptr = HEX_LUT.as_ptr();
 
         let r = ((self.0 & 0xFF0000) >> 15) as isize;
@@ -39,7 +42,7 @@ impl Color {
             ptr::copy_nonoverlapping(lut_ptr.offset(g), buf_ptr.offset(2), 2);
             ptr::copy_nonoverlapping(lut_ptr.offset(b), buf_ptr.offset(4), 2);
 
-            str::from_utf8(slice::from_raw_parts(buf_ptr, buf.len())).unwrap()
+            str::from_utf8(slice::from_raw_parts(buf_ptr, buf_len)).unwrap()
         }
     }
 }
@@ -50,7 +53,7 @@ impl Serialize for Color {
     where
         S: Serializer,
     {
-        let mut buf: [u8; 6] = unsafe { ::std::mem::uninitialized() };
+        let mut buf = MaybeUninit::uninit();
         serializer.serialize_str(self.as_str(&mut buf))
     }
 }
@@ -91,7 +94,7 @@ impl Encodable for Color {
     where
         S: Encoder,
     {
-        let mut buf: [u8; 6] = unsafe { ::std::mem::uninitialized() };
+        let mut buf = MaybeUninit::uninit();
         self.as_str(&mut buf).encode(s)
     }
 }
@@ -112,7 +115,7 @@ impl Decodable for Color {
 
 #[test]
 fn test_color() {
-    let mut buf: [u8; 6] = unsafe { ::std::mem::uninitialized() };
+    let mut buf = MaybeUninit::uninit();
     let string = Color(0xA0A0A0).as_str(&mut buf);
     assert_eq!(string, "A0A0A0");
 }