fix(nl): allow repeated flags to match GNU nl behavior (fixes #9132)

- Add .args_override_self(true) to Command builder to enable 'last wins' behavior
- Add .action(ArgAction::Append) to all 10 value-accepting arguments:
  - BODY_NUMBERING (-b), HEADER_NUMBERING (-h), FOOTER_NUMBERING (-f)
  - NUMBER_FORMAT (-n), NUMBER_SEPARATOR (-s), NUMBER_WIDTH (-w)
  - LINE_INCREMENT (-i), JOIN_BLANK_LINES (-l), STARTING_LINE_NUMBER (-v)
  - SECTION_DELIMITER (-d)
- Update helper.rs to use get_last() helper function to retrieve the last value
  from repeated arguments using get_many() and next_back()
- Add 10 regression tests to verify repeated flags are accepted and use last value

This matches GNU nl behavior where repeated flags are accepted and the last
occurrence's value is used, instead of rejecting with an error.

Author: naoNao89

src/uu/nl/src/helper.rs

@@ -16,7 +16,14 @@ pub fn parse_options(settings: &mut crate::Settings, opts: &clap::ArgMatches) ->
     // This vector holds error messages encountered.
     let mut errs: Vec<String> = vec![];
     settings.renumber = opts.get_flag(options::NO_RENUMBER);
-    if let Some(delimiter) = opts.get_one::<OsString>(options::SECTION_DELIMITER) {
+
+    // Helper function to get the last value from a repeated argument
+    fn get_last<T: Clone + Send + Sync + 'static>(opts: &clap::ArgMatches, key: &str) -> Option<T> {
+        opts.get_many::<T>(key)
+            .and_then(|mut values| values.next_back().cloned())
+    }
+
+    if let Some(delimiter) = get_last::<OsString>(opts, options::SECTION_DELIMITER) {
         // GNU nl determines whether a delimiter is a "single character" based on byte length, not
         // character length. A "single character" implies the second character is a ':'.
         settings.section_delimiter = if delimiter.len() == 1 {
@@ -27,53 +34,49 @@ pub fn parse_options(settings: &mut crate::Settings, opts: &clap::ArgMatches) ->
             delimiter.clone()
         };
     }
-    if let Some(val) = opts.get_one::<OsString>(options::NUMBER_SEPARATOR) {
-        settings.number_separator.clone_from(val);
+    if let Some(val) = get_last::<OsString>(opts, options::NUMBER_SEPARATOR) {
+        settings.number_separator.clone_from(&val);
     }
-    settings.number_format = opts
-        .get_one::<String>(options::NUMBER_FORMAT)
+    settings.number_format = get_last::<String>(opts, options::NUMBER_FORMAT)
         .map(Into::into)
         .unwrap_or_default();
-    match opts
-        .get_one::<String>(options::HEADER_NUMBERING)
-        .map(String::as_str)
+    match get_last::<String>(opts, options::HEADER_NUMBERING)
+        .as_deref()
         .map(TryInto::try_into)
     {
         None => {}
         Some(Ok(style)) => settings.header_numbering = style,
         Some(Err(message)) => errs.push(message),
     }
-    match opts
-        .get_one::<String>(options::BODY_NUMBERING)
-        .map(String::as_str)
+    match get_last::<String>(opts, options::BODY_NUMBERING)
+        .as_deref()
         .map(TryInto::try_into)
     {
         None => {}
         Some(Ok(style)) => settings.body_numbering = style,
         Some(Err(message)) => errs.push(message),
     }
-    match opts
-        .get_one::<String>(options::FOOTER_NUMBERING)
-        .map(String::as_str)
+    match get_last::<String>(opts, options::FOOTER_NUMBERING)
+        .as_deref()
         .map(TryInto::try_into)
     {
         None => {}
         Some(Ok(style)) => settings.footer_numbering = style,
         Some(Err(message)) => errs.push(message),
     }
-    match opts.get_one::<usize>(options::NUMBER_WIDTH) {
+    match get_last::<usize>(opts, options::NUMBER_WIDTH) {
         None => {}
-        Some(num) if *num > 0 => settings.number_width = *num,
+        Some(num) if num > 0 => settings.number_width = num,
         Some(_) => errs.push(translate!("nl-error-invalid-line-width", "value" => "0")),
     }
-    if let Some(num) = opts.get_one::<u64>(options::JOIN_BLANK_LINES) {
-        settings.join_blank_lines = *num;
+    if let Some(num) = get_last::<u64>(opts, options::JOIN_BLANK_LINES) {
+        settings.join_blank_lines = num;
     }
-    if let Some(num) = opts.get_one::<i64>(options::LINE_INCREMENT) {
-        settings.line_increment = *num;
+    if let Some(num) = get_last::<i64>(opts, options::LINE_INCREMENT) {
+        settings.line_increment = num;
     }
-    if let Some(num) = opts.get_one::<i64>(options::STARTING_LINE_NUMBER) {
-        settings.starting_line_number = *num;
+    if let Some(num) = get_last::<i64>(opts, options::STARTING_LINE_NUMBER) {
+        settings.starting_line_number = num;
     }
     errs
 }

src/uu/nl/src/nl.rs

@@ -245,6 +245,7 @@ pub fn uu_app() -> Command {
         .after_help(translate!("nl-after-help"))
         .infer_long_args(true)
         .disable_help_flag(true)
+        .args_override_self(true)
         .arg(
             Arg::new(options::HELP)
                 .long(options::HELP)
@@ -263,53 +264,60 @@ pub fn uu_app() -> Command {
                 .short('b')
                 .long(options::BODY_NUMBERING)
                 .help(translate!("nl-help-body-numbering"))
-                .value_name("STYLE"),
+                .value_name("STYLE")
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::SECTION_DELIMITER)
                 .short('d')
                 .long(options::SECTION_DELIMITER)
                 .help(translate!("nl-help-section-delimiter"))
                 .value_parser(clap::value_parser!(OsString))
-                .value_name("CC"),
+                .value_name("CC")
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::FOOTER_NUMBERING)
                 .short('f')
                 .long(options::FOOTER_NUMBERING)
                 .help(translate!("nl-help-footer-numbering"))
-                .value_name("STYLE"),
+                .value_name("STYLE")
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::HEADER_NUMBERING)
                 .short('h')
                 .long(options::HEADER_NUMBERING)
                 .help(translate!("nl-help-header-numbering"))
-                .value_name("STYLE"),
+                .value_name("STYLE")
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::LINE_INCREMENT)
                 .short('i')
                 .long(options::LINE_INCREMENT)
                 .help(translate!("nl-help-line-increment"))
                 .value_name("NUMBER")
-                .value_parser(clap::value_parser!(i64)),
+                .value_parser(clap::value_parser!(i64))
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::JOIN_BLANK_LINES)
                 .short('l')
                 .long(options::JOIN_BLANK_LINES)
                 .help(translate!("nl-help-join-blank-lines"))
                 .value_name("NUMBER")
-                .value_parser(clap::value_parser!(u64)),
+                .value_parser(clap::value_parser!(u64))
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::NUMBER_FORMAT)
                 .short('n')
                 .long(options::NUMBER_FORMAT)
                 .help(translate!("nl-help-number-format"))
                 .value_name("FORMAT")
-                .value_parser(["ln", "rn", "rz"]),
+                .value_parser(["ln", "rn", "rz"])
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::NO_RENUMBER)
@@ -324,23 +332,26 @@ pub fn uu_app() -> Command {
                 .long(options::NUMBER_SEPARATOR)
                 .help(translate!("nl-help-number-separator"))
                 .value_parser(clap::value_parser!(OsString))
-                .value_name("STRING"),
+                .value_name("STRING")
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::STARTING_LINE_NUMBER)
                 .short('v')
                 .long(options::STARTING_LINE_NUMBER)
                 .help(translate!("nl-help-starting-line-number"))
                 .value_name("NUMBER")
-                .value_parser(clap::value_parser!(i64)),
+                .value_parser(clap::value_parser!(i64))
+                .action(ArgAction::Append),
         )
         .arg(
             Arg::new(options::NUMBER_WIDTH)
                 .short('w')
                 .long(options::NUMBER_WIDTH)
                 .help(translate!("nl-help-number-width"))
                 .value_name("NUMBER")
-                .value_parser(clap::value_parser!(usize)),
+                .value_parser(clap::value_parser!(usize))
+                .action(ArgAction::Append),
         )
 }
 

tests/by-util/test_nl.rs

@@ -800,3 +800,102 @@ fn test_file_with_non_utf8_content() {
         String::from_utf8_lossy(invalid_utf8)
     ));
 }
+
+// Regression tests for issue #9132: repeated flags should use last value
+#[test]
+fn test_repeated_body_numbering_flag() {
+    // -ba -bt should use -bt (number all lines)
+    new_ucmd!()
+        .args(&["-ba", "-bt"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n     2\tb\n     3\tc\n");
+}
+
+#[test]
+fn test_repeated_header_numbering_flag() {
+    // -ha -ht should use -ht (number all lines in header)
+    new_ucmd!()
+        .args(&["-ha", "-ht"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n     2\tb\n     3\tc\n");
+}
+
+#[test]
+fn test_repeated_footer_numbering_flag() {
+    // -fa -ft should use -ft (number all lines in footer)
+    new_ucmd!()
+        .args(&["-fa", "-ft"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n     2\tb\n     3\tc\n");
+}
+
+#[test]
+fn test_repeated_number_format_flag() {
+    // -n ln -n rn should use -n rn (right-aligned)
+    new_ucmd!()
+        .args(&["-n", "ln", "-n", "rn"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n     2\tb\n     3\tc\n");
+}
+
+#[test]
+fn test_repeated_number_separator_flag() {
+    // -s ':' -s '|' should use -s '|'
+    new_ucmd!()
+        .args(&["-s", ":", "-s", "|"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1|a\n     2|b\n     3|c\n");
+}
+
+#[test]
+fn test_repeated_number_width_flag() {
+    // -w 3 -w 8 should use -w 8
+    new_ucmd!()
+        .args(&["-w", "3", "-w", "8"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("       1\ta\n       2\tb\n       3\tc\n");
+}
+
+#[test]
+fn test_repeated_line_increment_flag() {
+    // -i 1 -i 5 should use -i 5
+    new_ucmd!()
+        .args(&["-i", "1", "-i", "5"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n     6\tb\n    11\tc\n");
+}
+
+#[test]
+fn test_repeated_starting_line_number_flag() {
+    // -v 1 -v 10 should use -v 10
+    new_ucmd!()
+        .args(&["-v", "1", "-v", "10"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("    10\ta\n    11\tb\n    12\tc\n");
+}
+
+#[test]
+fn test_repeated_join_blank_lines_flag() {
+    // -l 1 -l 2 should use -l 2 (succeeds, not rejected)
+    new_ucmd!()
+        .args(&["-l", "1", "-l", "2"])
+        .pipe_in("a\nb")
+        .succeeds();
+}
+
+#[test]
+fn test_repeated_section_delimiter_flag() {
+    // -d ':' -d '|' should use -d '|' (succeeds, not rejected)
+    new_ucmd!()
+        .args(&["-d", ":", "-d", "|"])
+        .pipe_in("a\nb")
+        .succeeds();
+}