deprecated MaybeUninit slice conversion

Author: pascaldekloe

library/core/src/fmt/num.rs

@@ -295,14 +295,14 @@ macro_rules! impl_Display {
                     // not used: remain = 0;
                 }
 
-                // SAFETY: Offset has been used as a write index.
-                unsafe { core::hint::assert_unchecked(offset < buf.len()) }
-                let written = &buf[offset..];
                 // SAFETY: All buf content since offset is set with bytes form
                 // the lookup table, which consists of valid ASCII exclusively.
                 f.pad_integral(is_nonnegative, "", unsafe {
-                    let as_init = MaybeUninit::slice_assume_init_ref(written);
-                    str::from_utf8_unchecked(as_init)
+                    let written = buf.get_unchecked(offset..);
+                    str::from_utf8_unchecked(slice::from_raw_parts(
+                          MaybeUninit::slice_as_ptr(written),
+                          written.len(),
+                    ))
                 })
             }
         })*