use Validator to set Handler for VersionOption

src/System.CommandLine/Help/VersionOption.cs

@@ -1,8 +1,9 @@
 // Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.CommandLine.Invocation;
+using System.CommandLine.IO;
 using System.CommandLine.Parsing;
-using System.Linq;
 
 namespace System.CommandLine.Help
 {
@@ -29,23 +30,33 @@ private void AddValidators()
         {
             Validators.Add(static result =>
             {
-                if (result.Parent is CommandResult parent &&
-                    parent.Children.Where(r => !(r is OptionResult optionResult && optionResult.Option is VersionOption))
-                          .Any(IsNotImplicit))
+                CommandResult parent = (CommandResult)result.Parent!;
+
+                bool setHandler = true;
+                foreach (SymbolResult sibling in parent.Children)
                 {
-                    result.AddError(result.LocalizationResources.VersionOptionCannotBeCombinedWithOtherArguments(result.Token?.Value ?? result.Option.Name));
+                    setHandler = sibling switch
+                    {
+                        OptionResult optionResult => optionResult.IsImplicit || optionResult.Option is VersionOption,
+                        ArgumentResult argumentResult => argumentResult.IsImplicit,
+                        _ => false
+                    };
+
+                    if (!setHandler)
+                    {
+                        result.AddError(result.LocalizationResources.VersionOptionCannotBeCombinedWithOtherArguments(result.Token?.Value ?? result.Option.Name));
+                        break;
+                    }
                 }
-            });
-        }
 
-        private static bool IsNotImplicit(SymbolResult symbolResult)
-        {
-            return symbolResult switch
-            {
-                ArgumentResult argumentResult => !argumentResult.IsImplicit,
-                OptionResult optionResult => !optionResult.IsImplicit,
-                _ => true
-            };
+                if (setHandler)
+                {
+                    parent.Command.Handler = new AnonymousCommandHandler(static context =>
+                    {
+                        context.Console.Out.WriteLine(RootCommand.ExecutableVersion);
+                    });
+                }
+            });
         }
 
         public override string? Description

src/System.CommandLine/Parsing/ParseOperation.cs

@@ -3,8 +3,6 @@
 
 using System.Collections.Generic;
 using System.CommandLine.Help;
-using System.CommandLine.Invocation;
-using System.CommandLine.IO;
 
 namespace System.CommandLine.Parsing
 {
@@ -20,7 +18,6 @@ internal sealed class ParseOperation
         private Dictionary<string, IReadOnlyList<string>>? _directives;
         private CommandResult _innermostCommandResult;
         private bool _isHelpRequested;
-        private bool _isVersionRequested;
 
         public ParseOperation(
             List<Token> tokens,
@@ -62,7 +59,7 @@ internal ParseResult Parse(Parser parser)
                 Validate();
             }
 
-            ParseResult parseResult = new (
+            return new (
                 parser,
                 _rootCommandResult,
                 _innermostCommandResult,
@@ -71,17 +68,6 @@ internal ParseResult Parse(Parser parser)
                 _symbolResultTree.UnmatchedTokens,
                 _symbolResultTree.Errors,
                 _rawInput);
-
-            if (_isVersionRequested)
-            {
-                // FIX: (GetResult) use the ActiveOption's handler
-                parseResult.Handler = new AnonymousCommandHandler(context =>
-                {
-                    context.Console.Out.WriteLine(RootCommand.ExecutableVersion);
-                });
-            }
-
-            return parseResult;
         }
 
         private void ParseSubcommand()
@@ -191,10 +177,6 @@ private void ParseOption()
                 {
                     _isHelpRequested = true;
                 }
-                else if (option is VersionOption)
-                {
-                    _isVersionRequested = true;
-                }
 
                 optionResult = new OptionResult(
                     option,