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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"The first array type in a generic method doesn't work","articleBody":"### Prerequisites\n\n- [X] Write a descriptive title.\n- [X] Make sure you are able to repro it on the [latest released version](https://github.com/PowerShell/PowerShell/releases)\n- [X] Search the existing issues.\n- [X] Refer to the [FAQ](https://github.com/PowerShell/PowerShell/blob/master/docs/FAQ.md).\n- [X] Refer to [Differences between Windows PowerShell 5.1 and PowerShell](https://docs.microsoft.com/powershell/scripting/whats-new/differences-from-windows-powershell).\n\n### Steps to reproduce\n\nWhen I try to flatten a two-dimensional array by `Enumerable.SelectMany` method with generic type arguments, the first type argument `int[]` may not be treated correctly.\r\n```powershell\r\n[Linq.Enumerable]::SelectMany[int[], int](\r\n  [int[][]] @((,2), (,4), (,6), (,8)),\r\n  [Func[[int[]], int[]]] { param ($x); $x }\r\n) | ConvertTo-Json -Compress\r\n```\n\n### Expected behavior\n\n```console\n[2,4,6,8]\n```\n\n\n### Actual behavior\n\n```console\nUnable to find type [int,int].\n```\n\n\n### Error details\n\n```console\nException             :\r\n    Type        : System.Management.Automation.RuntimeException\r\n    ErrorRecord :\r\n        Exception             :\r\n            Type    : System.Management.Automation.ParentContainsErrorRecordException\r\n            Message : Unable to find type [int,int].\r\n            HResult : -2146233087\r\n        TargetObject          : int,int\r\n        CategoryInfo          : InvalidOperation: (int,int:TypeName) [], ParentContainsErrorRecordException\r\n        FullyQualifiedErrorId : TypeNotFound\r\n        InvocationInfo        :\r\n            ScriptLineNumber : 2\r\n            OffsetInLine     : 31\r\n            HistoryId        : -1\r\n            Line             : [Linq.Enumerable]::SelectMany[int[], int](\r\n\r\n            PositionMessage  : At line:2 char:31\r\n                               + [Linq.Enumerable]::SelectMany[int[], int](\r\n                               +                               ~~~~~\r\n            CommandOrigin    : Internal\r\n        ScriptStackTrace      : at \u003cScriptBlock\u003e, \u003cNo file\u003e: line 2\r\n    TargetSite  :\r\n        Name          : ResolveTypeName\r\n        DeclaringType : System.Management.Automation.TypeOps, System.Management.Automation, Version=7.3.0.500, Culture=\r\nneutral, PublicKeyToken=31bf3856ad364e35\r\n        MemberType    : Method\r\n        Module        : System.Management.Automation.dll\r\n    Message     : Unable to find type [int,int].\r\n    Data        : System.Collections.ListDictionaryInternal\r\n    Source      : System.Management.Automation\r\n    HResult     : -2146233087\r\n    StackTrace  :\r\n   at System.Management.Automation.TypeOps.ResolveTypeName(ITypeName typeName, IScriptExtent errorPos)\r\n   at System.Management.Automation.TypeOps.ResolveTypeName(ITypeName typeName, IScriptExtent errorPos)\r\n   at System.Management.Automation.Adapter.ResolveGenericTypeParameters(Object[] genericTypeParameters)\r\n   at System.Management.Automation.Adapter.FindBestMethodImpl(MethodInformation[] methods, PSMethodInvocationConstraint\r\ns invocationConstraints, Boolean allowCastingToByRefLikeType, Object[] arguments, String\u0026 errorId, String\u0026 errorMsg, Bo\r\nolean\u0026 expandParamsOnBest)\r\n   at System.Management.Automation.Adapter.FindBestMethod(MethodInformation[] methods, PSMethodInvocationConstraints in\r\nvocationConstraints, Boolean allowCastingToByRefLikeType, Object[] arguments, String\u0026 errorId, String\u0026 errorMsg, Boolea\r\nn\u0026 expandParamsOnBest, Boolean\u0026 callNonVirtually)\r\n   at System.Management.Automation.Language.PSInvokeMemberBinder.InvokeDotNetMethod(CallInfo callInfo, String name, PSM\r\nethodInvocationConstraints psMethodInvocationConstraints, MethodInvocationType methodInvocationType, DynamicMetaObject\r\ntarget, DynamicMetaObject[] args, BindingRestrictions restrictions, MethodInformation[] mi, Type errorExceptionType)\r\n   at System.Management.Automation.Language.PSInvokeMemberBinder.FallbackInvokeMember(DynamicMetaObject target, Dynamic\r\nMetaObject[] args, DynamicMetaObject errorSuggestion)\r\n   at System.Dynamic.DynamicMetaObjectBinder.Bind(Object[] args, ReadOnlyCollection`1 parameters, LabelTarget returnLab\r\nel)\r\n   at System.Runtime.CompilerServices.CallSiteBinder.BindCore[T](CallSite`1 site, Object[] args)\r\n   at System.Dynamic.UpdateDelegates.UpdateAndExecute3[T0,T1,T2,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2)\r\n   at System.Management.Automation.Interpreter.DynamicInstruction`4.Run(InterpretedFrame frame)\r\n   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)\r\nTargetObject          : int,int\r\nCategoryInfo          : InvalidOperation: (int,int:TypeName) [], RuntimeException\r\nFullyQualifiedErrorId : TypeNotFound\r\nInvocationInfo        :\r\n    ScriptLineNumber : 2\r\n    OffsetInLine     : 31\r\n    HistoryId        : -1\r\n    Line             : [Linq.Enumerable]::SelectMany[int[], int](\r\n\r\n    PositionMessage  : At line:2 char:31\r\n                       + [Linq.Enumerable]::SelectMany[int[], int](\r\n                       +                               ~~~~~\r\n    CommandOrigin    : Internal\r\nScriptStackTrace      : at \u003cScriptBlock\u003e, \u003cNo file\u003e: line 2\n```\n\n\n### Environment data\n\n```powershell\nName                           Value\r\n----                           -----\r\nPSVersion                      7.3.0\r\nPSEdition                      Core\r\nGitCommitId                    7.3.0\r\nOS                             Microsoft Windows 10.0.22621\r\nPlatform                       Win32NT\r\nPSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}\r\nPSRemotingProtocolVersion      2.3\r\nSerializationVersion           1.1.0.1\r\nWSManStackVersion              3.0\n```\n\n\n### Visuals\n\n_No response_","author":{"url":"https://github.com/InSb","@type":"Person","name":"InSb"},"datePublished":"2022-11-30T16:04:28.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/18686/PowerShell/issues/18686"}