Allow non-default encodings to be used in user's script/code (#18605)

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

@@ -1,10 +1,10 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System.Linq;
 using System.Management.Automation.Host;
 using System.Management.Automation.Language;
 using System.Management.Automation.Runspaces;
+using System.Text;
 
 namespace System.Management.Automation
 {
@@ -14,8 +14,15 @@ namespace System.Management.Automation
     /// </summary>
     internal class AutomationEngine
     {
+        static AutomationEngine()
+        {
+            // Register the encoding provider to load encodings that are not supported by default,
+            // so as to allow them to be used in user's script/code.
+            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+        }
+
         // Holds the parser to use for this instance of the engine...
-        internal Language.Parser EngineParser;
+        internal Parser EngineParser;
 
         /// <summary>
         /// Returns the handle to the execution context

src/System.Management.Automation/utils/ClrFacade.cs

@@ -107,10 +107,8 @@ namespace System.Management.Automation
         {
             if (s_oemEncoding == null)
             {
-                // load all available encodings
-                EncodingRegisterProvider();
 #if UNIX
-                s_oemEncoding = new UTF8Encoding(false);
+                s_oemEncoding = Encoding.Default;
 #else
                 uint oemCp = Interop.Windows.GetOEMCP();
                 s_oemEncoding = Encoding.GetEncoding((int)oemCp);
@@ -122,14 +120,6 @@ namespace System.Management.Automation
 
         private static volatile Encoding s_oemEncoding;
 
-        private static void EncodingRegisterProvider()
-        {
-            if (s_oemEncoding == null)
-            {
-                Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
-            }
-        }
-
         #endregion Encoding
 
 #if !UNIX

src/System.Management.Automation/utils/EncodingUtils.cs

@@ -30,21 +30,21 @@ namespace System.Management.Automation
 
         internal static readonly Dictionary<string, Encoding> encodingMap = new Dictionary<string, Encoding>(StringComparer.OrdinalIgnoreCase)
         {
-            { Ascii, System.Text.Encoding.ASCII },
-            { BigEndianUnicode, System.Text.Encoding.BigEndianUnicode },
+            { Ascii, Encoding.ASCII },
+            { BigEndianUnicode, Encoding.BigEndianUnicode },
             { BigEndianUtf32, new UTF32Encoding(bigEndian: true, byteOrderMark: true) },
             { Default, Encoding.Default },
             { OEM, ClrFacade.GetOEMEncoding() },
-            { Unicode, System.Text.Encoding.Unicode },
+            { Unicode, Encoding.Unicode },
 #pragma warning disable SYSLIB0001
-            { Utf7, System.Text.Encoding.UTF7 },
+            { Utf7, Encoding.UTF7 },
 #pragma warning restore SYSLIB0001
             { Utf8, Encoding.Default },
-            { Utf8Bom, System.Text.Encoding.UTF8 },
+            { Utf8Bom, Encoding.UTF8 },
             { Utf8NoBom, Encoding.Default },
-            { Utf32, System.Text.Encoding.UTF32 },
-            { String, System.Text.Encoding.Unicode },
-            { Unknown, System.Text.Encoding.Unicode },
+            { Utf32, Encoding.UTF32 },
+            { String, Encoding.Unicode },
+            { Unknown, Encoding.Unicode },
         };
 
         /// <summary>

test/powershell/Host/Startup.Tests.ps1

@@ -49,6 +49,7 @@ Describe "Validate start of console host" -Tag CI {
             'System.Security.AccessControl.dll'
             'System.Security.Cryptography.dll'
             'System.Security.Principal.Windows.dll'
+            'System.Text.Encoding.CodePages.dll'
             'System.Text.Encoding.Extensions.dll'
             'System.Text.RegularExpressions.dll'
             'System.Threading.dll'

test/powershell/Language/Scripting/Scripting.Followup.Tests.ps1

@@ -128,4 +128,10 @@ public class NullStringTest {
         [NullStringTest]::Get([NullString]::Value) | Should -BeExactly 'System.String'
         [NullStringTest]::Get(@('foo', [NullString]::Value, 'bar')) | Should -BeExactly 'System.String[]; 2nd element is NULL'
     }
+
+    It 'Non-default encoding should work in PowerShell' {
+        $powershell = Join-Path -Path $PSHOME -ChildPath "pwsh"
+        $result = & $powershell -noprofile -c '[System.Text.Encoding]::GetEncoding("IBM437").WebName'
+        $result | Should -BeExactly "ibm437"
+    }
 }