Upgrade to 2021 edition

Signed-off-by: Obei Sideg <[email protected]>

Author: obeis

Cargo.toml

@@ -8,7 +8,7 @@ authors = ["Liu Jiang <[email protected]>"]
 repository = "https://github.com/rust-vmm/vm-memory"
 readme = "README.md"
 license = "Apache-2.0 OR BSD-3-Clause"
-edition = "2018"
+edition = "2021"
 autobenches = false
 
 [features]

src/bitmap/backend/atomic_bitmap.rs

@@ -143,8 +143,6 @@ impl Default for AtomicBitmap {
 #[cfg(feature = "backend-mmap")]
 impl NewBitmap for AtomicBitmap {
     fn with_len(len: usize) -> Self {
-        use std::convert::TryFrom;
-
         let page_size;
 
         #[cfg(unix)]

src/volatile_memory.rs

@@ -24,7 +24,6 @@
 //! not reordered or elided the access.
 
 use std::cmp::min;
-use std::convert::TryFrom;
 use std::error;
 use std::fmt;
 use std::io::{self, Read, Write};