@@ -39,6 +39,33 @@ 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 for each PowerShell.
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+
66+ private static readonly PropertyInfo s_internalHostUIProperty ;
67+ #endif
68+
4269 private readonly ILoggerFactory _loggerFactory ;
4370
4471 private readonly ILogger _logger ;
@@ -104,6 +131,31 @@ static PsesInternalHost()
104131 s_scriptDebuggerTriggerObjectProperty = scriptDebuggerType . GetProperty (
105132 "TriggerObject" ,
106133 BindingFlags . Instance | BindingFlags . NonPublic ) ;
134+
135+ #if ! CoreCLR
136+ PropertyInfo transcribeOnlyProperty = typeof ( PSHostUserInterface )
137+ . GetProperty ( "TranscribeOnly" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
138+
139+ MethodInfo transcribeOnlyGetMethod = transcribeOnlyProperty . GetGetMethod ( nonPublic : true ) ;
140+
141+ s_getTranscribeOnlyDelegate = ( Func < PSHostUserInterface , bool > ) Delegate . CreateDelegate (
142+ typeof ( Func < PSHostUserInterface , bool > ) , transcribeOnlyGetMethod ) ;
143+
144+ MethodInfo transcribeOnlySetMethod = transcribeOnlyProperty . GetSetMethod ( nonPublic : true ) ;
145+
146+ s_setTranscribeOnlyDelegate = ( Action < PSHostUserInterface , bool > ) Delegate . CreateDelegate (
147+ typeof ( Action < PSHostUserInterface , bool > ) , transcribeOnlySetMethod ) ;
148+
149+ s_executionContextProperty = typeof ( System . Management . Automation . Runspaces . Runspace )
150+ . GetProperty ( "ExecutionContext" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
151+
152+ s_internalHostProperty = s_executionContextProperty . PropertyType
153+ . GetProperty ( "InternalHost" , BindingFlags . NonPublic | BindingFlags . Instance ) ;
154+
155+ // It's public but we want the override and reflection confuses me.
156+ s_internalHostUIProperty = s_internalHostProperty . PropertyType
157+ . GetProperty ( "UI" , BindingFlags . Public | BindingFlags . Instance ) ;
158+ #endif
107159 }
108160
109161 public PsesInternalHost (
@@ -476,19 +528,7 @@ public void InvokeDelegate(string representation, ExecutionOptions executionOpti
476528 public IReadOnlyList < TResult > InvokePSCommand < TResult > ( PSCommand psCommand , PowerShellExecutionOptions executionOptions , CancellationToken cancellationToken )
477529 {
478530 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- }
531+ return task . ExecuteAndGetResult ( cancellationToken ) ;
492532 }
493533
494534 public void InvokePSCommand ( PSCommand psCommand , PowerShellExecutionOptions executionOptions , CancellationToken cancellationToken ) => InvokePSCommand < PSObject > ( psCommand , executionOptions , cancellationToken ) ;
@@ -507,6 +547,29 @@ public void InvokePSDelegate(string representation, ExecutionOptions executionOp
507547
508548 internal void AddToHistory ( string historyEntry ) => _readLineProvider . ReadLine . AddToHistory ( historyEntry ) ;
509549
550+ // This works around a bug in PowerShell 5.1 (that was later fixed) where a running
551+ // transcription could cause output to disappear since the `TranscribeOnly` property was
552+ // accidentally not reset to false.
553+ #pragma warning disable CA1822 // Warning to make it static when it's empty for CoreCLR.
554+ internal void DisableTranscribeOnly ( )
555+ #pragma warning restore CA1822
556+ {
557+ #if ! CoreCLR
558+ // To fix the TranscribeOnly bug, we have to get the internal UI, which involves a lot
559+ // of reflection since we can't always just use PowerShell to execute `$Host.UI`.
560+ s_internalPSHostUserInterface ??=
561+ s_internalHostUIProperty . GetValue (
562+ s_internalHostProperty . GetValue (
563+ s_executionContextProperty . GetValue ( CurrentPowerShell . Runspace ) ) )
564+ as PSHostUserInterface ;
565+
566+ if ( s_getTranscribeOnlyDelegate ( s_internalPSHostUserInterface ) )
567+ {
568+ s_setTranscribeOnlyDelegate ( s_internalPSHostUserInterface , false ) ;
569+ }
570+ #endif
571+ }
572+
510573 internal Task LoadHostProfilesAsync ( CancellationToken cancellationToken )
511574 {
512575 // NOTE: This is a special task run on startup!
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