refactor/polish ~ fix cargo clippy complaints (unneeded format)

src/cp/cp.rs

@@ -979,7 +979,7 @@ fn copy_attribute(source: &Path, dest: &Path, attribute: &Attribute) -> CopyResu
             }
             #[cfg(not(unix))]
             {
-                return Err(format!("XAttrs are only supported on unix.").into());
+                return Err("XAttrs are only supported on unix.".to_string().into());
             }
         }
     })
@@ -1114,7 +1114,7 @@ fn copy_file(source: &Path, dest: &Path, options: &Options) -> CopyResult<()> {
 fn copy_helper(source: &Path, dest: &Path, options: &Options) -> CopyResult<()> {
     if options.reflink {
         #[cfg(not(target_os = "linux"))]
-        return Err(format!("--reflink is only supported on linux").into());
+        return Err("--reflink is only supported on linux".to_string().into());
 
         #[cfg(target_os = "linux")]
         {

src/od/od.rs

@@ -224,7 +224,7 @@ impl OdOptions {
         let formats = match parse_format_flags(&args) {
             Ok(f) => f,
             Err(e) => {
-                return Err(format!("{}", e));
+                return Err(e.to_string());
             }
         };
 
@@ -260,7 +260,7 @@ impl OdOptions {
             Some(s) => {
                 let st = s.into_bytes();
                 if st.len() != 1 {
-                    return Err(format!("Radix must be one of [d, o, n, x]"));
+                    return Err("Radix must be one of [d, o, n, x]".to_string());
                 } else {
                     let radix: char =
                         *(st.get(0).expect("byte string of length 1 lacks a 0th elem")) as char;
@@ -269,7 +269,7 @@ impl OdOptions {
                         'x' => Radix::Hexadecimal,
                         'o' => Radix::Octal,
                         'n' => Radix::NoPrefix,
-                        _ => return Err(format!("Radix must be one of [d, o, n, x]")),
+                        _ => return Err("Radix must be one of [d, o, n, x]".to_string()),
                     }
                 }
             }

src/od/parse_formats.rs

@@ -155,9 +155,7 @@ pub fn parse_format_flags(args: &Vec<String>) -> Result<Vec<ParsedFormatterItemI
         }
     }
     if expect_type_string {
-        return Err(format!(
-            "missing format specification after '--format' / '-t'"
-        ));
+        return Err("missing format specification after '--format' / '-t'".to_string());
     }
 
     if formats.is_empty() {

src/ptx/ptx.rs

@@ -271,7 +271,7 @@ fn get_reference(config: &Config, word_ref: &WordRef, line: &str) -> String {
             Some(x) => (x.start(), x.end()),
             None => (0, 0),
         };
-        format!("{}", &line[beg..end])
+        line[beg..end].to_string()
     } else {
         String::new()
     }