Fix clippy lints

src/colors.rs

@@ -1,6 +1,6 @@
 use std::fmt;
 
-#[derive(Debug, PartialEq, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
 /// The color type used to represent this image
 pub enum ColorType {
     /// Grayscale, with one color channel

src/deflate/mod.rs

@@ -62,7 +62,7 @@ pub fn zopfli_deflate(data: &[u8]) -> PngResult<Vec<u8>> {
     Ok(output)
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 /// DEFLATE algorithms supported by oxipng
 pub enum Deflaters {
     /// Use the Zlib/Miniz DEFLATE implementation

src/headers.rs

@@ -64,7 +64,7 @@ impl IhdrData {
     }
 }
 
-#[derive(Debug, PartialEq, Clone)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 /// Options to use for performing operations on headers (such as stripping)
 pub enum Headers {
     /// None

src/png/mod.rs

@@ -344,7 +344,7 @@ impl PngImage {
                         filter_line(filter, bpp, line.data, last_line, &mut f_buf);
                         let size = f_buf.iter().fold(0_u64, |acc, &x| {
                             let signed = x as i8;
-                            acc + i16::from(signed).abs() as u64
+                            acc + i16::from(signed).unsigned_abs() as u64
                         });
                         if size < best_size {
                             best_size = size;

src/reduction/color.rs

@@ -53,7 +53,7 @@ pub fn reduce_rgba_to_grayscale_alpha(png: &PngImage) -> Option<PngImage> {
 
     let mut aux_headers = png.aux_headers.clone();
     if let Some(sbit_header) = png.aux_headers.get(b"sBIT") {
-        if let Some(&s) = sbit_header.get(0) {
+        if let Some(&s) = sbit_header.first() {
             aux_headers.insert(*b"sBIT", vec![s]);
         }
     }
@@ -247,7 +247,7 @@ pub fn reduce_rgb_to_grayscale(png: &PngImage) -> Option<PngImage> {
 
     let mut aux_headers = png.aux_headers.clone();
     if let Some(sbit_header) = png.aux_headers.get(b"sBIT") {
-        if let Some(&byte) = sbit_header.get(0) {
+        if let Some(&byte) = sbit_header.first() {
             aux_headers.insert(*b"sBIT", vec![byte]);
         }
     }

src/reduction/mod.rs

@@ -117,7 +117,7 @@ fn do_palette_reduction(png: &PngImage, palette_map: &[Option<u8>; 256]) -> Opti
     let mut aux_headers = png.aux_headers.clone();
     if let Some(bkgd_header) = png.aux_headers.get(b"bKGD") {
         if let Some(Some(map_to)) = bkgd_header
-            .get(0)
+            .first()
             .and_then(|&idx| palette_map.get(idx as usize))
         {
             aux_headers.insert(*b"bKGD", vec![*map_to]);