This project started as a fork of the Windows PowerShell 5.1 code base. As we've progressed towards a PowerShell Core 6.0 release and with the capability of dotnet core 2.0 and dotnet std 2.0 being able to load dotnet framework 4.5.1+ assemblies that are compatible with dotnet std 2.0, we can simplify the code base by removing the legacy FullCLR code so that we no longer have #ifdefs for CORECLR (and !CORECLR). This was discussed and approved by @PowerShell/powershell-committee. When reviewing the code, do not blindly just remove the FullCLR code, but validate if updates to .NET Core means using the FullCLR code instead of the limited .NET Core code.

Remaining #if [!]CORECLR usages

param($path = "../repos/PowerShell")

$sources = Get-ChildItem -Recurse -Path $path -Include *.cs
foreach ($source in $sources) {
    $content = Get-Content $source -Raw
    if ($content -match "#if CORECLR" -or $content -match "#if !CORECLR") {
        $source.FullName
    }
}

src/Microsoft.PowerShell.Commands.Diagnostics/CoreCLR/Stubs.cs
src/Microsoft.PowerShell.Commands.Diagnostics/CommonUtils.cs
src/Microsoft.PowerShell.Commands.Diagnostics/ExportCounterCommand.cs
src/Microsoft.PowerShell.Commands.Diagnostics/GetCounterCommand.cs
src/Microsoft.PowerShell.Commands.Diagnostics/ImportCounterCommand.cs
src/Microsoft.PowerShell.Commands.Diagnostics/NewWinEventCommand.cs
src/Microsoft.PowerShell.Commands.Utility/commands/utility/new-object.cs
src/Microsoft.PowerShell.LocalAccounts/LocalAccounts/Extensions.cs
src/Microsoft.PowerShell.LocalAccounts/LocalAccounts/Sam.cs
src/Microsoft.PowerShell.Security/security/AclCommands.cs
src/Microsoft.PowerShell.Security/security/CertificateProvider.cs
src/Microsoft.PowerShell.Security/security/ExecutionPolicyCommands.cs
src/Microsoft.WSMan.Management/CredSSP.cs
src/Microsoft.WSMan.Management/Interop.cs
src/Microsoft.WSMan.Management/WsManHelper.cs
src/System.Management.Automation/cimSupport/cmdletization/xml/CoreCLR/cmdlets-over-objects.xmlSerializer.autogen.cs
src/System.Management.Automation/cimSupport/cmdletization/ScriptWriter.cs
src/System.Management.Automation/CoreCLR/CorePsAssemblyLoadContext.cs
src/System.Management.Automation/DscSupport/CimDSCParser.cs
src/System.Management.Automation/engine/debugger/debugger.cs
src/System.Management.Automation/engine/hostifaces/Command.cs
src/System.Management.Automation/engine/hostifaces/Connection.cs
src/System.Management.Automation/engine/hostifaces/ConnectionBase.cs
src/System.Management.Automation/engine/hostifaces/HostUtilities.cs
src/System.Management.Automation/engine/hostifaces/InternalHost.cs
src/System.Management.Automation/engine/hostifaces/LocalConnection.cs
src/System.Management.Automation/engine/hostifaces/LocalPipeline.cs
src/System.Management.Automation/engine/hostifaces/Parameter.cs
src/System.Management.Automation/engine/hostifaces/PowerShell.cs
src/System.Management.Automation/engine/hostifaces/PowerShellProcessInstance.cs
src/System.Management.Automation/engine/hostifaces/RunspacePool.cs
src/System.Management.Automation/engine/hostifaces/RunspacePoolInternal.cs
src/System.Management.Automation/engine/interpreter/ControlFlowInstructions.cs
src/System.Management.Automation/engine/Modules/ModuleCmdletBase.cs
src/System.Management.Automation/engine/parser/Compiler.cs
src/System.Management.Automation/engine/parser/FusionAssemblyIdentity.cs
src/System.Management.Automation/engine/parser/GlobalAssemblyCache.cs
src/System.Management.Automation/engine/parser/Parser.cs
src/System.Management.Automation/engine/parser/TypeResolver.cs
src/System.Management.Automation/engine/remoting/client/remoterunspace.cs
src/System.Management.Automation/engine/remoting/commands/CustomShellCommands.cs
src/System.Management.Automation/engine/remoting/commands/EnterPSHostProcessCommand.cs
src/System.Management.Automation/engine/remoting/commands/remotingcommandutil.cs
src/System.Management.Automation/engine/remoting/commands/ResumeJob.cs
src/System.Management.Automation/engine/remoting/commands/SuspendJob.cs
src/System.Management.Automation/engine/remoting/common/WireDataFormat/EncodeAndDecode.cs
src/System.Management.Automation/engine/remoting/common/RemoteSessionNamedPipe.cs
src/System.Management.Automation/engine/remoting/common/RunspaceConnectionInfo.cs
src/System.Management.Automation/engine/remoting/common/throttlemanager.cs
src/System.Management.Automation/engine/remoting/fanin/BaseTransportManager.cs
src/System.Management.Automation/engine/remoting/fanin/InitialSessionStateProvider.cs
src/System.Management.Automation/engine/remoting/fanin/WSManPlugin.cs
src/System.Management.Automation/engine/remoting/fanin/WSManPluginFacade.cs
src/System.Management.Automation/engine/remoting/fanin/WSManTransportManager.cs
src/System.Management.Automation/engine/remoting/server/OutOfProcServerMediator.cs
src/System.Management.Automation/engine/remoting/server/ServerPowerShellDriver.cs
src/System.Management.Automation/engine/remoting/server/serverremotesession.cs
src/System.Management.Automation/engine/remoting/server/ServerRunspacePoolDriver.cs
src/System.Management.Automation/engine/remoting/server/ServerSteppablePipelineDriver.cs
src/System.Management.Automation/engine/Attributes.cs
src/System.Management.Automation/engine/CommandDiscovery.cs
src/System.Management.Automation/engine/CommandMetadata.cs
src/System.Management.Automation/engine/ExecutionContext.cs
src/System.Management.Automation/engine/GetEvent_Types_Ps1Xml.cs
src/System.Management.Automation/engine/InitialSessionState.cs
src/System.Management.Automation/engine/LanguagePrimitives.cs
src/System.Management.Automation/engine/MshCommandRuntime.cs
src/System.Management.Automation/engine/pipeline.cs
src/System.Management.Automation/engine/serialization.cs
src/System.Management.Automation/engine/Types_Ps1Xml.cs
src/System.Management.Automation/engine/Utils.cs
src/System.Management.Automation/help/HelpSystem.cs
src/System.Management.Automation/help/UpdatableHelpCommandBase.cs
src/System.Management.Automation/help/UpdatableHelpSystem.cs
src/System.Management.Automation/help/UpdateHelpCommand.cs
src/System.Management.Automation/logging/MshLog.cs
src/System.Management.Automation/namespaces/FileSystemProvider.cs
src/System.Management.Automation/namespaces/RegistryProvider.cs
src/System.Management.Automation/namespaces/Win32Native.cs
src/System.Management.Automation/security/SecureStringHelper.cs
src/System.Management.Automation/singleshell/config/MshSnapinInfo.cs
src/System.Management.Automation/utils/ClrFacade.cs
src/System.Management.Automation/utils/StructuredTraceSource.cs