nl: accept negative -v and -i values given as separate arguments

GNU nl accepts a negative starting line number or increment passed as a
separate argument, such as `nl -v -5` or `nl -i -2`. uutils only accepted
the attached forms (`-v-5`, `--starting-line-number=-5`); the space-
separated form failed with "unexpected argument '-5' found" because clap
treated the leading-hyphen token as an unknown flag.

Set allow_hyphen_values on the -v and -i arguments so the negative value
is consumed as the option value, matching GNU. The value parser was
already i64, so negative numbers were always intended.

Add tests covering the space-separated form for both options.

Author: cho-minsung

src/uu/nl/src/nl.rs

@@ -329,6 +329,7 @@ pub fn uu_app() -> Command {
                 .long(options::LINE_INCREMENT)
                 .help(translate!("nl-help-line-increment"))
                 .value_name("NUMBER")
+                .allow_hyphen_values(true)
                 .value_parser(clap::value_parser!(i64)),
         )
         .arg(
@@ -368,6 +369,7 @@ pub fn uu_app() -> Command {
                 .long(options::STARTING_LINE_NUMBER)
                 .help(translate!("nl-help-starting-line-number"))
                 .value_name("NUMBER")
+                .allow_hyphen_values(true)
                 .value_parser(clap::value_parser!(i64)),
         )
         .arg(

tests/by-util/test_nl.rs

@@ -254,6 +254,17 @@ fn test_negative_starting_line_number() {
     }
 }
 
+#[test]
+fn test_negative_starting_line_number_space_separated() {
+    // GNU nl accepts a negative value passed as a separate argument, e.g.
+    // `nl -v -10`. Without `allow_hyphen_values` clap rejected the `-10` token.
+    new_ucmd!()
+        .args(&["-v", "-10"])
+        .pipe_in("test")
+        .succeeds()
+        .stdout_is("   -10\ttest\n");
+}
+
 #[test]
 fn test_invalid_starting_line_number() {
     for arg in ["-vinvalid", "--starting-line-number=invalid"] {
@@ -298,6 +309,16 @@ fn test_negative_line_increment() {
     }
 }
 
+#[test]
+fn test_negative_line_increment_space_separated() {
+    // GNU nl accepts `nl -i -10` with the value as a separate argument.
+    new_ucmd!()
+        .args(&["-i", "-10"])
+        .pipe_in("a\nb\nc")
+        .succeeds()
+        .stdout_is("     1\ta\n    -9\tb\n   -19\tc\n");
+}
+
 #[test]
 fn test_invalid_line_increment() {
     for arg in ["-iinvalid", "--line-increment=invalid"] {