Resolve -WindowStyle Hidden console flashing

src/Microsoft.PowerShell.ConsoleHost/host/msh/CommandLineParameterParser.cs

@@ -13,6 +13,7 @@
 using System.Management.Automation.Internal;
 using System.Management.Automation.Language;
 using System.Management.Automation.Runspaces;
+using System.Runtime.InteropServices;
 using System.Security;
 using System.Text;
 
@@ -524,6 +525,10 @@ internal static void EarlyParse(string[] args)
             }
 
             bool noexitSeen = false;
+#if !UNIX
+            bool consoleAllocated = false;
+            bool consoleAttached = false;
+#endif
             for (int i = 0; i < args.Length; ++i)
             {
                 (string SwitchKey, bool ShouldBreak) switchKeyResults = GetSwitchKey(args, ref i, parser: null, ref noexitSeen);
@@ -542,7 +547,51 @@ internal static void EarlyParse(string[] args)
                         break;
                     }
                 }
+                else if (MatchSwitch(switchKey, "windowstyle", "w"))
+                {
+#if UNIX
+                    break;
+#else
+                    ++i;
+                    if (i >= args.Length)
+                    {
+                        break;
+                    }
+
+                    try
+                    {
+                        ProcessWindowStyle style = (ProcessWindowStyle)LanguagePrimitives.ConvertTo(
+                            args[i],
+                            typeof(ProcessWindowStyle),
+                            CultureInfo.InvariantCulture);
+
+                        if (style.HasFlag(ProcessWindowStyle.Hidden))
+                        {
+                            // Attach to parent process console.
+                            // AttachConsole(-1) returns false if we run pwsh from Win-R dialog.
+                            // In the case we haven't parent console so ignore error and always set the flag to true.
+                            consoleAttached = true;
+                            AttachConsole(-1);
+                        }
+                        else
+                        {
+                            consoleAllocated = AllocConsole();
+                            ConsoleControl.SetConsoleMode(style);
+                        }
+                    }
+                    catch (PSInvalidCastException)
+                    {
+                        break;
+                    }
+#endif
+                }
             }
+#if !UNIX
+            if (!consoleAttached && !consoleAllocated)
+            {
+                AllocConsole();
+            }
+#endif
         }
 
         /// <summary>
@@ -827,7 +876,6 @@ private void ParseHelper(string[] args)
                     {
                         ProcessWindowStyle style = (ProcessWindowStyle)LanguagePrimitives.ConvertTo(
                             args[i], typeof(ProcessWindowStyle), CultureInfo.InvariantCulture);
-                        ConsoleControl.SetConsoleMode(style);
                     }
                     catch (PSInvalidCastException e)
                     {
@@ -1436,7 +1484,15 @@ private bool CollectArgs(string[] args, ref int i)
 
 #if !UNIX
         private bool _removeWorkingDirectoryTrailingCharacter = false;
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static extern bool AllocConsole();
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        internal static extern bool AttachConsole(int dwProcessId);
+
 #endif
     }
-}   // namespace
-
+}

src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHostRawUserInterface.cs

@@ -35,8 +35,16 @@ class ConsoleHostRawUserInterface : System.Management.Automation.Host.PSHostRawU
         internal
         ConsoleHostRawUserInterface(ConsoleHostUserInterface mshConsole) : base()
         {
-            defaultForeground = ForegroundColor;
-            defaultBackground = BackgroundColor;
+            try
+            {
+                defaultForeground = ForegroundColor;
+                defaultBackground = BackgroundColor;
+            }
+            catch (HostException)
+            {
+                // Ignore this as it means we're running -WindowStyle Hidden
+            }
+
             parent = mshConsole;
             // cacheKeyEvent is a value type and initialized automatically
 

src/Microsoft.PowerShell.ConsoleHost/host/msh/ManagedEntrance.cs

@@ -32,6 +32,18 @@ public sealed class UnmanagedPSEntry
         /// </param>
         public static int Start(string consoleFilePath, [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPWStr, SizeParamIndex = 2)]string[] args, int argc)
         {
+#if DEBUG
+            if (args.Length > 0 && !string.IsNullOrEmpty(args[0]) && args[0].Equals("-isswait", StringComparison.OrdinalIgnoreCase))
+            {
+                Console.WriteLine("Attach the debugger to continue...");
+                while (!System.Diagnostics.Debugger.IsAttached)
+                {
+                    Thread.Sleep(100);
+                }
+
+                System.Diagnostics.Debugger.Break();
+            }
+#endif
             // Warm up some components concurrently on background threads.
             EarlyStartup.Init();
 
@@ -54,18 +66,6 @@ public static int Start(string consoleFilePath, [MarshalAs(UnmanagedType.LPArray
             Thread.CurrentThread.CurrentUICulture = NativeCultureResolver.UICulture;
             Thread.CurrentThread.CurrentCulture = NativeCultureResolver.Culture;
 
-#if DEBUG
-            if (args.Length > 0 && !string.IsNullOrEmpty(args[0]) && args[0].Equals("-isswait", StringComparison.OrdinalIgnoreCase))
-            {
-                Console.WriteLine("Attach the debugger to continue...");
-                while (!System.Diagnostics.Debugger.IsAttached)
-                {
-                    Thread.Sleep(100);
-                }
-
-                System.Diagnostics.Debugger.Break();
-            }
-#endif
             int exitCode = 0;
             try
             {

src/System.Management.Automation/engine/PSConfiguration.cs

@@ -439,7 +439,7 @@ private T ReadValueFromFile<T>(ConfigScope scope, string key, T defaultValue = d
 
             if (configData != emptyConfig && configData.TryGetValue(key, StringComparison.OrdinalIgnoreCase, out JToken jToken))
             {
-                return jToken.ToObject<T>(serializer);
+                return jToken.ToObject<T>(serializer) ?? defaultValue;
             }
 
             return defaultValue;

src/powershell-win-core/powershell-win-core.csproj

@@ -4,7 +4,7 @@
   <PropertyGroup>
     <Description>PowerShell on Windows top-level project</Description>
     <AssemblyName>pwsh</AssemblyName>
-    <OutputType>Exe</OutputType>
+    <OutputType>WinExe</OutputType>
     <TieredCompilation>true</TieredCompilation>
     <TieredCompilationQuickJit>true</TieredCompilationQuickJit>
     <RuntimeIdentifiers>win7-x86;win7-x64</RuntimeIdentifiers>