chore: fix new linting problems (#50)

Author: rvagg

examples/readme.rs

@@ -1,5 +1,6 @@
 // NOTE: This file should be kept in sync with README.md
 
+#[cfg(feature = "std")]
 use serde_derive::{Deserialize, Serialize};
 #[cfg(feature = "std")]
 use std::error::Error;
@@ -10,6 +11,7 @@ use std::io::BufReader;
 
 // Types annotated with `Serialize` can be stored as DAG-CBOR.
 // To be able to load them again add `Deserialize`.
+#[cfg(feature = "std")]
 #[derive(Debug, Serialize, Deserialize)]
 struct Mascot {
     name: String,

tests/enum.rs

@@ -85,11 +85,3 @@ fn test_variable_length_array_error() {
     let value: Result<Vec<Foo>, _> = from_slice(slice);
     assert!(matches!(value.unwrap_err(), DecodeError::IndefiniteSize));
 }
-
-#[derive(Serialize, Deserialize, PartialEq, Debug)]
-enum Bar {
-    Empty,
-    Number(i32),
-    Flag(String, bool),
-    Point { x: i32, y: i32 },
-}

tests/ipld.rs

@@ -79,12 +79,6 @@ fn unit_struct_not_supported() {
     assert!(ipld.is_err());
 }
 
-#[derive(Debug, Deserialize, Serialize)]
-struct SmallStruct {
-    spam: u32,
-    eggs: u32,
-}
-
 #[derive(Debug, PartialEq, Clone, Deserialize_tuple, Serialize_tuple)]
 #[serde(deny_unknown_fields)]
 struct StructWithTupleSerialization {

tests/std_types.rs

@@ -3,7 +3,7 @@ use serde_derive::{Deserialize, Serialize};
 use serde_ipld_dagcbor::{from_slice, to_vec};
 
 fn to_binary(s: &'static str) -> Vec<u8> {
-    assert!(s.len() % 2 == 0);
+    assert!(s.len().is_multiple_of(2));
     let mut b = Vec::with_capacity(s.len() / 2);
     for i in 0..s.len() / 2 {
         b.push(u8::from_str_radix(&s[i * 2..(i + 1) * 2], 16).unwrap());