upgrade to rust 2021 edition

Cargo.toml

@@ -7,6 +7,8 @@ license = "MIT OR Apache-2.0"
 name = "hash32"
 repository = "https://github.com/japaric/hash32"
 version = "0.3.1"
+edition = "2021"
+rust-version = "1.56"
 
 [dependencies.byteorder]
 default-features = false

README.md

@@ -19,3 +19,7 @@ at your option.
 Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the
 work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
 additional terms or conditions.
+
+## Minimum Supported Rust Version (MSRV)
+This crate is guaranteed to compile on stable Rust 1.56 and up. It *might*
+compile with older versions but that may change in any new patch release.

src/lib.rs

@@ -56,8 +56,8 @@ use core::fmt;
 use core::hash::BuildHasher;
 use core::marker::PhantomData;
 
-pub use fnv::Hasher as FnvHasher;
-pub use murmur3::Hasher as Murmur3Hasher;
+pub use crate::fnv::Hasher as FnvHasher;
+pub use crate::murmur3::Hasher as Murmur3Hasher;
 
 mod fnv;
 mod murmur3;

src/murmur3.rs

@@ -139,7 +139,7 @@ impl core::hash::Hasher for Hasher {
                 let mid = 4 - index;
                 let head = unsafe { slice::from_raw_parts(bytes.as_ptr(), mid) };
                 let body = unsafe {
-                    slice::from_raw_parts(bytes.as_ptr().offset(mid as isize), len - mid)
+                    slice::from_raw_parts(bytes.as_ptr().add(mid), len - mid)
                 };
 
                 // NOTE(unsafe) avoid calling `memcpy` on a 0-3 byte copy