Added `-W:experimental` command line option

[Feature #16420]

ruby.c

@@ -1078,6 +1078,9 @@ proc_options(long argc, char **argv, ruby_cmdline_options_t *opt, int envopt)
                 if (NAME_MATCH_P("deprecated", s, len)) {
                     bits = 1U << RB_WARN_CATEGORY_DEPRECATED;
                 }
+                else if (NAME_MATCH_P("experimental", s, len)) {
+                    bits = 1U << RB_WARN_CATEGORY_EXPERIMENTAL;
+                }
                 else {
                     rb_warn("unknown warning category: `%s'", s);
                 }

test/ruby/test_rubyoptions.rb

@@ -77,6 +77,8 @@ class TestRubyOptions < Test::Unit::TestCase
     assert_in_out_err(%w(-w -W0 -e) + ['p $-W'], "", %w(0), [])
     assert_in_out_err(%w(-W:deprecated -e) + ['p Warning[:deprecated]'], "", %w(true), [])
     assert_in_out_err(%w(-W:no-deprecated -e) + ['p Warning[:deprecated]'], "", %w(false), [])
+    assert_in_out_err(%w(-W:experimental -e) + ['p Warning[:experimental]'], "", %w(true), [])
+    assert_in_out_err(%w(-W:no-experimental -e) + ['p Warning[:experimental]'], "", %w(false), [])
     assert_in_out_err(%w(-W:qux), "", [], /unknown warning category: `qux'/)
   ensure
     ENV['RUBYOPT'] = save_rubyopt
@@ -335,6 +337,10 @@ class TestRubyOptions < Test::Unit::TestCase
     assert_in_out_err(%w(), "p Warning[:deprecated]", ["true"])
     ENV['RUBYOPT'] = '-W:no-deprecated'
     assert_in_out_err(%w(), "p Warning[:deprecated]", ["false"])
+    ENV['RUBYOPT'] = '-W:experimental'
+    assert_in_out_err(%w(), "p Warning[:experimental]", ["true"])
+    ENV['RUBYOPT'] = '-W:no-experimental'
+    assert_in_out_err(%w(), "p Warning[:experimental]", ["false"])
     ENV['RUBYOPT'] = '-W:qux'
     assert_in_out_err(%w(), "", [], /unknown warning category: `qux'/)
   ensure