date: handle unknown options gracefully

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

@@ -104,3 +104,4 @@ date-error-date-overflow = date overflow '{$date}'
 date-error-setting-date-not-supported-macos = setting the date is not supported by macOS
 date-error-setting-date-not-supported-redox = setting the date is not supported by Redox
 date-error-cannot-set-date = cannot set date
+date-error-extra-operand = extra operand '{$operand}'

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

@@ -99,3 +99,4 @@ date-error-date-overflow = débordement de date '{$date}'
 date-error-setting-date-not-supported-macos = la définition de la date n'est pas prise en charge par macOS
 date-error-setting-date-not-supported-redox = la définition de la date n'est pas prise en charge par Redox
 date-error-cannot-set-date = impossible de définir la date
+date-error-extra-operand = opérande supplémentaire '{$operand}'

src/uu/date/src/date.rs

@@ -169,7 +169,28 @@ fn parse_military_timezone_with_offset(s: &str) -> Option<i32> {
 #[uucore::main]
 #[allow(clippy::cognitive_complexity)]
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
-    let matches = uucore::clap_localization::handle_clap_result(uu_app(), args)?;
+    let args: Vec<std::ffi::OsString> = args.collect();
+    let matches = match uu_app().try_get_matches_from(&args) {
+        Ok(matches) => matches,
+        Err(e) => {
+            match e.kind() {
+                clap::error::ErrorKind::DisplayHelp | clap::error::ErrorKind::DisplayVersion => {
+                    return Err(e.into());
+                }
+                _ => {
+                    // Convert unknown options to be treated as invalid date format
+                    // This ensures consistent exit status 1 instead of clap's exit status 77
+                    if let Some(arg) = args.get(1) {
+                        return Err(USimpleError::new(
+                            1,
+                            translate!("date-error-invalid-date", "date" => arg.to_string_lossy()),
+                        ));
+                    }
+                    return Err(USimpleError::new(1, e.to_string()));
+                }
+            }
+        }
+    };
 
     // Check for extra operands (multiple positional arguments)
     if let Some(formats) = matches.get_many::<String>(OPT_FORMAT) {
@@ -526,7 +547,7 @@ pub fn uu_app() -> Command {
                 .help(translate!("date-help-universal"))
                 .action(ArgAction::SetTrue),
         )
-        .arg(Arg::new(OPT_FORMAT).num_args(0..))
+        .arg(Arg::new(OPT_FORMAT).num_args(0..).trailing_var_arg(true))
 }
 
 /// Return the appropriate format string for the given settings.

tests/by-util/test_date.rs

@@ -32,6 +32,30 @@ fn test_extra_operands() {
         .stderr_contains("extra operand 'extra'");
 }
 
+#[test]
+fn test_invalid_long_option() {
+    new_ucmd!()
+        .arg("--fB")
+        .fails_with_code(1)
+        .stderr_contains("invalid date '--fB'");
+}
+
+#[test]
+fn test_invalid_short_option() {
+    new_ucmd!()
+        .arg("-w")
+        .fails_with_code(1)
+        .stderr_contains("invalid date '-w'");
+}
+
+#[test]
+fn test_single_dash_as_date() {
+    new_ucmd!()
+        .arg("-")
+        .fails_with_code(1)
+        .stderr_contains("invalid date");
+}
+
 #[test]
 fn test_date_email() {
     for param in ["--rfc-email", "--rfc-e", "-R", "--rfc-2822", "--rfc-822"] {