Reject command line option ending with `-`

ruby.c

@@ -1460,7 +1460,8 @@ proc_options(long argc, char **argv, ruby_cmdline_options_t *opt, int envopt)
 #	define is_option_with_arg(name, allow_hyphen, allow_envopt)	\
 	    is_option_with_optarg(name, allow_hyphen, allow_envopt, Qtrue, Qtrue)
 #	define is_option_with_optarg(name, allow_hyphen, allow_envopt, needs_arg, next_arg) \
-	    (strncmp((name), s, n = sizeof(name) - 1) == 0 && is_option_end(s[n], (allow_hyphen)) ? \
+	    (strncmp((name), s, n = sizeof(name) - 1) == 0 && is_option_end(s[n], (allow_hyphen)) && \
+             (s[n] != '-' || s[n+1]) ? \
 	     (check_envopt(name, (allow_envopt)), s += n, \
 	      need_argument(name, s, needs_arg, next_arg), 1) : 0)
 

test/ruby/test_rubyoptions.rb

@@ -121,6 +121,8 @@ class TestRubyOptions < Test::Unit::TestCase
 
     assert_in_out_err(["--disable-gems", "--debug", "-e", "p $DEBUG"],
                       "", %w(true), [])
+
+    assert_in_out_err(["--disable-gems", "--debug-", "-e", "p $DEBUG"], "", %w(), /invalid option --debug-/)
   end
 
   q = Regexp.method(:quote)