cli/parser: allow commands that look like options

Library/Homebrew/cli/parser.rb

@@ -264,6 +264,7 @@ def parse_remaining(argv, ignore_invalid_options: false)
         remaining = []
 
         argv, non_options = split_non_options(argv)
+        allow_commands = Array(@named_args_type).include?(:command)
 
         while i < argv.count
           begin
@@ -279,7 +280,7 @@ def parse_remaining(argv, ignore_invalid_options: false)
               i += 1
             end
           rescue OptionParser::InvalidOption
-            if ignore_invalid_options
+            if ignore_invalid_options || (allow_commands && Commands.path(arg))
               remaining << arg
             else
               $stderr.puts generate_help_text

Library/Homebrew/test/cli/parser_spec.rb

@@ -559,5 +559,19 @@
         Homebrew::CLI::MaxNamedArgumentsError, /This command does not take more than 1 formula or cask argument/
       )
     end
+
+    it "accepts commands with :command" do
+      parser = described_class.new do
+        named_args :command
+      end
+      expect { parser.parse(["--prefix", "--version"]) }.not_to raise_error
+    end
+
+    it "doesn't accept invalid options with :command" do
+      parser = described_class.new do
+        named_args :command
+      end
+      expect { parser.parse(["--not-a-command"]) }.to raise_error(OptionParser::InvalidOption, /--not-a-command/)
+    end
   end
 end