Prefer implementing Display over a custom .display() method

src/files.rs

@@ -81,23 +81,16 @@ fn read_file_arg(file_arg: &FileArgument) -> std::io::Result<Vec<u8>> {
 fn eprint_read_error(file_arg: &FileArgument, e: &std::io::Error) {
     match e.kind() {
         std::io::ErrorKind::NotFound => {
-            eprintln!("No such file: {}", file_arg.display());
+            eprintln!("No such file: {}", file_arg);
         }
         std::io::ErrorKind::PermissionDenied => {
-            eprintln!(
-                "Permission denied when reading file: {}",
-                file_arg.display()
-            );
+            eprintln!("Permission denied when reading file: {}", file_arg);
         }
         _ => match file_arg {
             FileArgument::NamedPath(path) if path.is_dir() => {
                 eprintln!("Expected a file, got a directory: {}", path.display());
             }
-            _ => eprintln!(
-                "Could not read file: {} (error {:?})",
-                file_arg.display(),
-                e.kind()
-            ),
+            _ => eprintln!("Could not read file: {} (error {:?})", file_arg, e.kind()),
         },
     };
 }

src/options.rs

@@ -1,6 +1,6 @@
 //! CLI option parsing.
 
-use std::{env, ffi::OsStr, path::Path, path::PathBuf};
+use std::{env, ffi::OsStr, fmt::Display, path::Path, path::PathBuf};
 
 use clap::{crate_authors, crate_description, Arg, Command};
 use const_format::formatcp;
@@ -352,12 +352,16 @@ impl FileArgument {
             FileArgument::NamedPath(PathBuf::from(arg))
         }
     }
+}
 
-    pub(crate) fn display(&self) -> String {
+impl Display for FileArgument {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            FileArgument::NamedPath(path) => relative_to_current(path).display().to_string(),
-            FileArgument::Stdin => "(stdin)".to_string(),
-            FileArgument::DevNull => "/dev/null".to_string(),
+            FileArgument::NamedPath(path) => {
+                write!(f, "{}", relative_to_current(path).display())
+            }
+            FileArgument::Stdin => write!(f, "(stdin)"),
+            FileArgument::DevNull => write!(f, "/dev/null"),
         }
     }
 }