tac: fix error message (#9942)

* tac: fix error message

* tac: Remove obsolete error messages from locales

src/uu/tac/locales/en-US.ftl

@@ -6,7 +6,7 @@ tac-help-separator = use STRING as the separator instead of newline
 
 # Error messages
 tac-error-invalid-regex = invalid regular expression: { $error }
-tac-error-invalid-argument = { $argument }: read error: Invalid argument
+tac-error-invalid-directory-argument = { $argument }: read error: Is a directory
 tac-error-file-not-found = failed to open { $filename } for reading: No such file or directory
 tac-error-read-error = failed to read from { $filename }: { $error }
 tac-error-write-error = failed to write to stdout: { $error }

src/uu/tac/locales/fr-FR.ftl

@@ -6,7 +6,7 @@ tac-help-separator = utiliser CHAÎNE comme séparateur au lieu du saut de ligne
 
 # Messages d'erreur
 tac-error-invalid-regex = expression régulière invalide : { $error }
-tac-error-invalid-argument = { $argument } : erreur de lecture : Argument invalide
 tac-error-file-not-found = échec de l'ouverture de { $filename } en lecture : Aucun fichier ou répertoire de ce type
 tac-error-read-error = échec de la lecture depuis { $filename } : { $error }
 tac-error-write-error = échec de l'écriture vers stdout : { $error }
+tac-error-invalid-directory-argument = { $argument } : erreur de lecture : Est un répertoire

src/uu/tac/src/error.rs

@@ -15,9 +15,9 @@ pub enum TacError {
     /// A regular expression given by the user is invalid.
     #[error("{}", translate!("tac-error-invalid-regex", "error" => .0))]
     InvalidRegex(regex::Error),
-    /// An argument to tac is invalid.
-    #[error("{}", translate!("tac-error-invalid-argument", "argument" => .0.maybe_quote()))]
-    InvalidArgument(OsString),
+    /// The argument to tac is a directory.
+    #[error("{}", translate!("tac-error-invalid-directory-argument", "argument" => .0.maybe_quote()))]
+    InvalidDirectoryArgument(OsString),
     /// The specified file is not found on the filesystem.
     #[error("{}", translate!("tac-error-file-not-found", "filename" => .0.quote()))]
     FileNotFound(OsString),

src/uu/tac/src/tac.rs

@@ -253,7 +253,8 @@ fn tac(filenames: &[OsString], before: bool, regex: bool, separator: &str) -> UR
         } else {
             let path = Path::new(filename);
             if path.is_dir() {
-                let e: Box<dyn UError> = TacError::InvalidArgument(filename.clone()).into();
+                let e: Box<dyn UError> =
+                    TacError::InvalidDirectoryArgument(filename.clone()).into();
                 show!(e);
                 continue;
             }

tests/by-util/test_tac.rs

@@ -100,7 +100,7 @@ fn test_invalid_input() {
         .ucmd()
         .arg("a")
         .fails()
-        .stderr_contains("a: read error: Invalid argument");
+        .stderr_contains("a: read error: Is a directory");
 }
 
 #[test]