Bump MSRV to 1.57 (#788)

src/bytes_mut.rs

@@ -1,8 +1,7 @@
-use core::iter::FromIterator;
 use core::mem::{self, ManuallyDrop, MaybeUninit};
 use core::ops::{Deref, DerefMut};
 use core::ptr::{self, NonNull};
-use core::{cmp, fmt, hash, isize, slice, usize};
+use core::{cmp, fmt, hash, slice};
 
 use alloc::{
     borrow::{Borrow, BorrowMut},
@@ -17,7 +16,7 @@ use crate::bytes::Vtable;
 #[allow(unused)]
 use crate::loom::sync::atomic::AtomicMut;
 use crate::loom::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
-use crate::{offset_from, Buf, BufMut, Bytes, TryGetError};
+use crate::{Buf, BufMut, Bytes, TryGetError};
 
 /// A unique reference to a contiguous slice of memory.
 ///
@@ -694,7 +693,7 @@ impl BytesMut {
                 let v_capacity = v.capacity();
                 let ptr = v.as_mut_ptr();
 
-                let offset = offset_from(self.ptr.as_ptr(), ptr);
+                let offset = self.ptr.as_ptr().offset_from(ptr) as usize;
 
                 // Compare the condition in the `kind == KIND_VEC` case above
                 // for more details.
@@ -1722,7 +1721,7 @@ impl From<BytesMut> for Vec<u8> {
             let shared = bytes.data as *mut Shared;
 
             if unsafe { (*shared).is_unique() } {
-                let vec = mem::replace(unsafe { &mut (*shared).vec }, Vec::new());
+                let vec = core::mem::take(unsafe { &mut (*shared).vec });
 
                 unsafe { release_shared(shared) };
 
@@ -1797,7 +1796,7 @@ unsafe fn shared_v_to_vec(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> V
         let shared = &mut *shared;
 
         // Drop shared
-        let mut vec = mem::replace(&mut shared.vec, Vec::new());
+        let mut vec = core::mem::take(&mut shared.vec);
         release_shared(shared);
 
         // Copy back buffer
@@ -1823,7 +1822,7 @@ unsafe fn shared_v_to_mut(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> B
         let v = &mut shared.vec;
         let v_capacity = v.capacity();
         let v_ptr = v.as_mut_ptr();
-        let offset = offset_from(ptr as *mut u8, v_ptr);
+        let offset = ptr.offset_from(v_ptr) as usize;
         let cap = v_capacity - offset;
 
         let ptr = vptr(ptr as *mut u8);