base32/base64/basenc: accept a -w value starting with - to match GNU

src/uu/base32/src/base_common.rs

@@ -124,6 +124,8 @@ pub fn base_app(about: String, usage: String) -> Command {
                 .short('w')
                 .long(options::WRAP)
                 .value_name("COLS")
+                // GNU takes the token after -w as the wrap size even when it starts with '-'.
+                .allow_hyphen_values(true)
                 .help(translate!("base-common-help-wrap", "default" => WRAP_DEFAULT))
                 .overrides_with(options::WRAP),
         )

tests/by-util/test_base64.rs

@@ -219,6 +219,20 @@ fn test_wrap_bad_arg() {
     }
 }
 
+#[test]
+fn test_wrap_negative_arg() {
+    // GNU consumes the token after -w as the wrap size even when it begins
+    // with '-', reporting it as an invalid wrap size rather than an unknown
+    // option.
+    for arg in ["-5", "-d"] {
+        new_ucmd!()
+            .arg("-w")
+            .arg(arg)
+            .fails()
+            .stderr_only(format!("base64: invalid wrap size: '{arg}'\n"));
+    }
+}
+
 #[test]
 fn test_base64_extra_operand() {
     // Expect a failure when multiple files are specified.