trigger help display using HelpException

src/dotnet/HelpException.cs

@@ -0,0 +1,23 @@
+using System;
+using Microsoft.DotNet.Cli.Utils;
+
+namespace Microsoft.DotNet.Cli
+{
+    /// 
+    /// <summary>Allows control flow to be interrupted in order to display help in the console.</summary>
+    ///
+    [Obsolete("This is intended to facilitate refactoring during parser replacement and should not be used after that work is done.")]
+    public class HelpException : Exception
+    {
+        public HelpException(
+            string message,
+            bool isError = false) : base(message)
+        {
+            IsError = isError;
+
+            Data.Add(ExceptionExtensions.CLI_User_Displayed_Exception, true);
+        }
+
+        public bool IsError { get; }
+    }
+}

src/dotnet/ParseResultExtensions.cs

@@ -7,18 +7,20 @@ using Microsoft.DotNet.Cli.CommandLine;
 
 namespace Microsoft.DotNet.Cli
 {
-    public static class ParserExtensions
-    {
-        public static ParseResult ParseFrom(
-            this CommandLine.Parser parser,
-            string context,
-            string[] args) =>
-            parser.Parse(context.Split(' ').Concat(args).ToArray());
-    }
-
     public static class ParseResultExtensions
     {
         public static void ShowHelp(this ParseResult parseResult) =>
             Console.WriteLine(parseResult.Command().HelpView());
+
+        public static void ShowHelpIfRequested(this ParseResult parseResult)
+        {
+            if (parseResult.HasOption("help"))
+            {
+
+                // NOTE: this is a temporary stage in refactoring toward the ClicCommandLineParser being used at the CLI entry point. 
+
+                throw new HelpException(parseResult.Command().HelpView());
+            }
+        }
     }
 }

src/dotnet/ParserExtensions.cs

@@ -0,0 +1,14 @@
+using System.Linq;
+using Microsoft.DotNet.Cli.CommandLine;
+
+namespace Microsoft.DotNet.Cli
+{
+    public static class ParserExtensions
+    {
+        public static ParseResult ParseFrom(
+            this CommandLine.Parser parser,
+            string context,
+            string[] args) =>
+            parser.Parse(context.Split(' ').Concat(args).ToArray());
+    }
+}

src/dotnet/Program.cs

@@ -77,6 +77,11 @@ namespace Microsoft.DotNet.Cli
                     return ProcessArgs(args);
                 }
             }
+            catch (HelpException e)
+            {
+                Reporter.Output.Write(e.Message);
+                return e.IsError ? 1 : 0;
+            }
             catch (Exception e) when (e.ShouldBeDisplayedAsError())
             {
                 Reporter.Error.WriteLine(CommandContext.IsVerbose() ? 

src/dotnet/commands/dotnet-publish/Program.cs

@@ -25,6 +25,8 @@ namespace Microsoft.DotNet.Tools.Publish
 
             var result = parser.ParseFrom("dotnet publish", args);
 
+            result.ShowHelpIfRequested();
+
             msbuildArgs.Add("/t:Publish");
 
             var appliedPublishOption = result["dotnet"]["publish"];

src/dotnet/commands/dotnet-restore/Program.cs

@@ -29,6 +29,8 @@ namespace Microsoft.DotNet.Tools.Restore
 
             var result = parser.ParseFrom("dotnet restore", args);
 
+            result.ShowHelpIfRequested();
+
             Reporter.Output.WriteLine(result.Diagram());
 
             var restore = result["dotnet"]["restore"];
@@ -60,7 +62,7 @@ namespace Microsoft.DotNet.Tools.Restore
             {
                 return e.ExitCode;
             }
-
+            
             return cmd.Execute();
         }
     }