What causes "%s: option `-W %s' doesn't allow an argument" in NationalSecurityAgency/ghidra?

Remove the argument from the no-argument option

%s: option `-W %s' doesn't allow an argument

Error message

%s: option `-W %s' doesn't allow an argument

What it means

Using `-W foo`, the option `foo` was found (pfound != NULL) but it takes no argument (pfound->has_arg is false). The user attached an argument via `=value` or ran it directly into the option name (nameend is non-empty). getopt reports the rejection and returns '?'.

Source

Thrown at GPL/DemanglerGnu/src/demangler_gnu_v2_24/c/getopt.c:892

	      fprintf (stderr, _("%s: option `-W %s' is ambiguous\n"),
		       argv[0], argv[optind]);
	    nextchar += strlen (nextchar);
	    optind++;
	    return '?';
	  }
	if (pfound != NULL)
	  {
	    option_index = indfound;
	    if (*nameend)
	      {
		/* Don't test has_arg with >, because some C compilers don't
		   allow it to be used on enums.  */
		if (pfound->has_arg)
		  optarg = nameend + 1;
		else
		  {
		    if (opterr)
		      fprintf (stderr, _("\
%s: option `-W %s' doesn't allow an argument\n"),
			       argv[0], pfound->name);

		    nextchar += strlen (nextchar);
		    return '?';
		  }
	      }
	    else if (pfound->has_arg == 1)
	      {
		if (optind < argc)
		  optarg = argv[optind++];
		else
		  {
		    if (opterr)
		      fprintf (stderr,
			       _("%s: option `%s' requires an argument\n"),
			       argv[0], argv[optind - 1]);
		    nextchar += strlen (nextchar);

View on GitHub (pinned to d5f144c24d)

Solutions

Remove the argument from the no-argument option
Verify which options accept values via `--help`
Use a separate flag if you need to set a value

Example fix

// before
./tool -W strip=true
// after
./tool -W strip  # strip takes no argument

Defensive patterns

Strategy: validation

Validate before calling

// Check if a -W option accepts an argument before attaching one
static int w_option_accepts_arg(const char *name, const struct option *longopts) {
    for (const struct option *o = longopts; o->name; o++) {
        if (strcmp(o->name, name) == 0) return o->has_arg != 0;
    }
    return -1; // unknown option
}

Try / catch

int c;
while ((c = getopt_long(argc, argv, optstring, longopts, NULL)) != -1) {
    if (c == '?') { exit(EXIT_FAILURE); }
}

Prevention

Check has_arg for each option in the longopts table
Do not attach =value to no_argument options
Document which options accept values in --help

When it happens

Trigger: User passes `-W flag=value` or `-W flagvalue` where `flag` has has_arg == 0 (no_argument). nameend points past the option name and is non-empty. opterr is non-zero.

Common situations: Passing a value to a boolean/flag option via -W; misunderstanding which options accept arguments; copy-pasting a command that worked with a different option.

Related errors

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/b6f6898a20b5bdfd. Report an issue: GitHub.