Replace UTF8Encoding(false) with Encoding.Default (PowerShell#18144)

Author: xtqqczze

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

@@ -4340,7 +4340,7 @@ static InitialSessionState()
                 // Variable which controls the encoding for piping data to a NativeCommand
                 new SessionStateVariableEntry(
                     SpecialVariables.OutputEncoding,
-                    Utils.utf8NoBom,
+                    Encoding.Default,
                     RunspaceInit.OutputEncodingDescription,
                     ScopedItemOptions.None,
                     new ArgumentTypeConverterAttribute(typeof(System.Text.Encoding))),

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

@@ -2057,11 +2057,12 @@ internal void Start(Process process, NativeCommandIOFormat inputFormat)
             // Get the encoding for writing to native command. Note we get the Encoding
             // from the current scope so a script or function can use a different encoding
             // than global value.
-            Encoding pipeEncoding = _command.Context.GetVariableValue(SpecialVariables.OutputEncodingVarPath) as System.Text.Encoding ??
-                                    Utils.utf8NoBom;
+            Encoding outputEncoding = _command.Context.GetVariableValue(SpecialVariables.OutputEncodingVarPath) as Encoding;
 
-            _streamWriter = new StreamWriter(process.StandardInput.BaseStream, pipeEncoding);
-            _streamWriter.AutoFlush = true;
+            _streamWriter = new StreamWriter(process.StandardInput.BaseStream, outputEncoding ?? Encoding.Default)
+            {
+                AutoFlush = true
+            };
 
             _inputFormat = inputFormat;
 

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

@@ -1380,9 +1380,6 @@ internal static bool Succeeded(int hresult)
         //     Add-Member ScriptProperty Preamble { $this.GetEncoding().GetPreamble() -join "-" } -PassThru |
         //     Format-Table -Auto
 
-        internal static readonly UTF8Encoding utf8NoBom =
-            new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
-
 #if !UNIX
         /// <summary>
         /// Queues a CLR worker thread with impersonation of provided Windows identity.

src/System.Management.Automation/engine/hostifaces/MshHostUserInterface.cs

@@ -1243,7 +1243,7 @@ internal void FlushContentToDisk()
         {
             static Encoding GetPathEncoding(string path)
             {
-                using StreamReader reader = new StreamReader(path, Utils.utf8NoBom, detectEncodingFromByteOrderMarks: true);
+                using StreamReader reader = new StreamReader(path, Encoding.Default, detectEncodingFromByteOrderMarks: true);
                 _ = reader.Read();
                 return reader.CurrentEncoding;
             }
@@ -1271,7 +1271,7 @@ static Encoding GetPathEncoding(string path)
                             // file permissions.
                             _contentWriter = new StreamWriter(
                                 new FileStream(this.Path, FileMode.Append, FileAccess.Write, FileShare.Read),
-                                Utils.utf8NoBom);
+                                Encoding.Default);
                         }
 
                         _contentWriter.AutoFlush = true;

src/System.Management.Automation/engine/remoting/common/RunspaceConnectionInfo.cs

@@ -18,6 +18,7 @@
 using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Security.AccessControl;
+using System.Text;
 using System.Threading;
 
 using Microsoft.Win32.SafeHandles;
@@ -2404,23 +2405,31 @@ internal static int StartSSHProcess(
             if (startInfo.RedirectStandardInput)
             {
                 Debug.Assert(stdinFd >= 0, "Invalid Fd");
-                standardInput = new StreamWriter(OpenStream(stdinFd, FileAccess.Write),
-                    Utils.utf8NoBom, StreamBufferSize)
+                standardInput = new StreamWriter(
+                    OpenStream(stdinFd, FileAccess.Write),
+                    Encoding.Default,
+                    StreamBufferSize)
                 { AutoFlush = true };
             }
 
             if (startInfo.RedirectStandardOutput)
             {
                 Debug.Assert(stdoutFd >= 0, "Invalid Fd");
-                standardOutput = new StreamReader(OpenStream(stdoutFd, FileAccess.Read),
-                    startInfo.StandardOutputEncoding ?? Utils.utf8NoBom, true, StreamBufferSize);
+                standardOutput = new StreamReader(
+                    OpenStream(stdoutFd, FileAccess.Read),
+                    startInfo.StandardOutputEncoding ?? Encoding.Default,
+                    detectEncodingFromByteOrderMarks: true,
+                    StreamBufferSize);
             }
 
             if (startInfo.RedirectStandardError)
             {
                 Debug.Assert(stderrFd >= 0, "Invalid Fd");
-                standardError = new StreamReader(OpenStream(stderrFd, FileAccess.Read),
-                    startInfo.StandardErrorEncoding ?? Utils.utf8NoBom, true, StreamBufferSize);
+                standardError = new StreamReader(
+                    OpenStream(stderrFd, FileAccess.Read),
+                    startInfo.StandardErrorEncoding ?? Encoding.Default,
+                    detectEncodingFromByteOrderMarks: true,
+                    StreamBufferSize);
             }
 
             return childPid;