exclude --help and --version options from binding

Author: jonsequitur

src/System.CommandLine/Builder/CommandLineBuilderExtensions.cs

@@ -515,6 +515,8 @@ public static CommandLineBuilder UseVersionOption(
                     return true;
                 });
 
+            versionOption.DisallowBinding = true;
+
             command.AddOption(versionOption);
 
             builder.AddMiddleware(async (context, next) =>

src/System.CommandLine/Help/HelpOption.cs

@@ -12,8 +12,9 @@ public HelpOption() : base(new[]
             "--help",
             "-?",
             "/?"
-        }, Resources.Instance.HelpOptionDescription() )
+        }, Resources.Instance.HelpOptionDescription())
         {
+            DisallowBinding = true;
         }
 
         internal override Argument Argument
@@ -22,11 +23,6 @@ internal override Argument Argument
             set { }
         }
 
-        protected bool Equals(HelpOption other)
-        {
-            return other != null;
-        }
-
         public override bool Equals(object obj)
         {
             return obj is HelpOption;

src/System.CommandLine/Option.cs

@@ -122,6 +122,8 @@ public bool ArgumentIsHidden
 
         private IEnumerable<Argument> Arguments => Children.OfType<Argument>();
 
+        internal bool DisallowBinding { get; set; } 
+
         public override string Name
         {
             get => base.Name;

src/System.CommandLine/Parsing/CommandResultExtensions.cs

@@ -37,9 +37,10 @@ internal static bool TryGetValueForOption(
 
             for (var i = 0; i < options.Count; i++)
             {
-                var option = options[i];
+                var option = (Option) options[i];
 
-                if (valueDescriptor.ValueName.IsMatch(option))
+                if (!option.DisallowBinding &&
+                    valueDescriptor.ValueName.IsMatch(option))
                 {
                     var optionResult = commandResult.FindResultFor(option);