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COM objects are not enumerating properly #3775
Description
Repro
Open a File Explorer window first if you find $w.Count is 0
PSv6> $s = New-Object -ComObject "Shell.Application"
PSv6> $w = $s.Windows()
PSv6> $w.Count
1
PSv6> $w ## dump $w, and powershell should enumerate $w to unwrap the collection
Expected Behavior
$w is unwrapped and the contained items are dumpped out (PSv5 behavior)
Application : System.__ComObject
Parent : System.__ComObject
Container :
Document : System.__ComObject
TopLevelContainer : True
Type :
Left : -32000
Top : -32000
Width : 160
Height : 28
LocationName : 6.0.0-beta1
LocationURL : file:///D:/PowerShell/6.0.0-beta1
Busy : False
Name : File Explorer
HWND : 923136
FullName : C:\WINDOWS\Explorer.EXE
Path : C:\WINDOWS\
Visible : True
StatusBar : False
StatusText :
ToolBar : 1
MenuBar : False
FullScreen : False
ReadyState : 4
Offline : False
Silent : False
RegisterAsBrowser : False
RegisterAsDropTarget : True
TheaterMode : False
AddressBar : True
Resizable : True
Actual Behavior
Count
-----
2
Environment
PSv6> $PSVersionTable
Name Value
---- -----
PSVersion 6.0.0-beta
PSEdition Core
BuildVersion 3.0.0.0
CLRVersion
GitCommitId v6.0.0-beta.1
OS Microsoft Windows 10.0.15063
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
Additional Observation
The problem appears to be this:
PSv6> $w._NewEnum()
An error occurred while enumerating through a collection: Could not load type 'System.Runtime.InteropServices.ComTypes.IEnumerator' from assembly 'System.Private.CoreLib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=7cec85d7bea7798e'..
At line:1 char:2
+ $w._NewEnum()
+ ~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (System.__ComObject:__ComObject) [], RuntimeException
+ FullyQualifiedErrorId : BadEnumeration
Activity
daxian-dbw commentedon May 12, 2017
Good catch 👍
My investigation shows this is a bug in .NET Core 2.0. A dotnet/corefx issue has been filed: https://github.com/dotnet/corefx/issues/19731
What happens is that powershell successfully casts the
ShellWindowsobject toIEnumerable, and then aTypeLoadExceptionis thrown when callingGetEnumerator()on theIEnumerableobject. PowerShell catches the exception and treat the object as non-enumerable.daxian-dbw commentedon May 12, 2017
The issue description was updated to make it easy to understand the problem.
daxian-dbw commentedon May 24, 2017
Reply from
CoreCLRteam on dotnet/corefx#19731So we need to write the enumeration code ourselves.
iSazonov commentedon May 25, 2017
Should we remove Waiting - NetStandard20 label?