@@ -39,6 +39,31 @@ internal class PsesInternalHost : PSHost, IHostSupportsInteractiveSession, IRuns
3939
4040 private static readonly PropertyInfo s_scriptDebuggerTriggerObjectProperty ;
4141
42+ #if ! CoreCLR
43+ /// <summary>
44+ /// To workaround a horrid bug where the `TranscribeOnly` field of the PSHostUserInterface
45+ /// can accidentally remain true, we have to use a bunch of reflection so that <see
46+ /// cref="DisableTranscribeOnly()" /> can reset it to false. (This was fixed in PowerShell
47+ /// 7.) Note that it must be the internal UI instance, not our own UI instance, otherwise
48+ /// this would be easier. Because of the amount of reflection involved, we contain it to
49+ /// only PowerShell 5.1 at compile-time, and we have to set this up in this class, not <see
50+ /// cref="SynchronousPowerShellTask" /> because that's templated, making statics practically
51+ /// useless. <see cref = "SynchronousPowerShellTask.ExecuteNormally" /> method calls <see
52+ /// cref="DisableTranscribeOnly()" /> when necessary.
53+ /// See: https://github.com/PowerShell/PowerShell/pull/3436
54+ /// </summary>
55+ [ ThreadStatic ] // Because we can re-use it, but only once per instance of PSES.
56+ private static PSHostUserInterface s_internalPSHostUserInterface ;
57+
58+ private static readonly Func < PSHostUserInterface , bool > s_getTranscribeOnlyDelegate ;
59+
60+ private static readonly Action < PSHostUserInterface , bool > s_setTranscribeOnlyDelegate ;
61+
62+ private static readonly PropertyInfo s_executionContextProperty ;
63+
64+ private static readonly PropertyInfo s_internalHostProperty ;
65+ #endif
66+
4267 private readonly ILoggerFactory _loggerFactory ;
4368
4469 private readonly ILogger _logger ;
@@ -104,6 +129,27 @@ static PsesInternalHost()
104129 s_scriptDebuggerTriggerObjectProperty = scriptDebuggerType . GetProperty (
105130 "TriggerObject" ,
106131 BindingFlags . Instance | BindingFlags . NonPublic ) ;
132+
133+ #if ! CoreCLR
134+ PropertyInfo transcribeOnlyProperty = typeof ( PSHostUserInterface )
135+ . GetProperty ( "TranscribeOnly" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
136+
137+ MethodInfo transcribeOnlyGetMethod = transcribeOnlyProperty . GetGetMethod ( nonPublic : true ) ;
138+
139+ s_getTranscribeOnlyDelegate = ( Func < PSHostUserInterface , bool > ) Delegate . CreateDelegate (
140+ typeof ( Func < PSHostUserInterface , bool > ) , transcribeOnlyGetMethod ) ;
141+
142+ MethodInfo transcribeOnlySetMethod = transcribeOnlyProperty . GetSetMethod ( nonPublic : true ) ;
143+
144+ s_setTranscribeOnlyDelegate = ( Action < PSHostUserInterface , bool > ) Delegate . CreateDelegate (
145+ typeof ( Action < PSHostUserInterface , bool > ) , transcribeOnlySetMethod ) ;
146+
147+ s_executionContextProperty = typeof ( System . Management . Automation . Runspaces . Runspace )
148+ . GetProperty ( "ExecutionContext" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
149+
150+ s_internalHostProperty = s_executionContextProperty . PropertyType
151+ . GetProperty ( "InternalHost" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
152+ #endif
107153 }
108154
109155 public PsesInternalHost (
@@ -476,19 +522,7 @@ public void InvokeDelegate(string representation, ExecutionOptions executionOpti
476522 public IReadOnlyList < TResult > InvokePSCommand < TResult > ( PSCommand psCommand , PowerShellExecutionOptions executionOptions , CancellationToken cancellationToken )
477523 {
478524 SynchronousPowerShellTask < TResult > task = new ( _logger , this , psCommand , executionOptions , cancellationToken ) ;
479- try
480- {
481- return task . ExecuteAndGetResult ( cancellationToken ) ;
482- }
483- finally
484- {
485- // At the end of each PowerShell command we need to reset PowerShell 5.1's
486- // `TranscribeOnly` property to avoid a bug where output disappears.
487- if ( UI is EditorServicesConsolePSHostUserInterface ui )
488- {
489- ui . DisableTranscribeOnly ( ) ;
490- }
491- }
525+ return task . ExecuteAndGetResult ( cancellationToken ) ;
492526 }
493527
494528 public void InvokePSCommand ( PSCommand psCommand , PowerShellExecutionOptions executionOptions , CancellationToken cancellationToken ) => InvokePSCommand < PSObject > ( psCommand , executionOptions , cancellationToken ) ;
@@ -507,6 +541,28 @@ public void InvokePSDelegate(string representation, ExecutionOptions executionOp
507541
508542 internal void AddToHistory ( string historyEntry ) => _readLineProvider . ReadLine . AddToHistory ( historyEntry ) ;
509543
544+ // This works around a bug in PowerShell 5.1 (that was later fixed) where a running
545+ // transcription could cause output to disappear since the `TranscribeOnly` property was
546+ // accidentally not reset to false.
547+ #pragma warning disable CA1822 // Warning to make it static when it's empty for CoreCLR.
548+ internal void DisableTranscribeOnly ( )
549+ #pragma warning restore CA1822
550+ {
551+ #if ! CoreCLR
552+ // To fix the TranscribeOnly bug, we have to get the internal UI, which involves a lot
553+ // of reflection since we can't always just use PowerShell to execute `$Host.UI`.
554+ s_internalPSHostUserInterface ??=
555+ ( s_internalHostProperty . GetValue (
556+ s_executionContextProperty . GetValue ( CurrentPowerShell . Runspace ) )
557+ as PSHost ) . UI ;
558+
559+ if ( s_getTranscribeOnlyDelegate ( s_internalPSHostUserInterface ) )
560+ {
561+ s_setTranscribeOnlyDelegate ( s_internalPSHostUserInterface , false ) ;
562+ }
563+ #endif
564+ }
565+
510566 internal Task LoadHostProfilesAsync ( CancellationToken cancellationToken )
511567 {
512568 // NOTE: This is a special task run on startup!
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