Parser throws with using statement aliases on new lines

[MartinGC94]

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

Type in any of the following lines and add a linebreak after the equals sign:

using namespace whatever =
using module whatever =
using type whatever =
using command whatever =

As soon as you add the new line, PSReadline will display a parser error:

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Management.Automation.Language.Parser.ExtentOf(Token first, Ast last)
   at System.Management.Automation.Language.Parser.UsingStatementRule(Token usingToken)
   at System.Management.Automation.Language.Parser.UsingStatementsRule()

The same thing happens in PowerShell 5.1

Expected behavior

No errors thrown.

Actual behavior

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Management.Automation.Language.Parser.ExtentOf(Token first, Ast last)
   at System.Management.Automation.Language.Parser.UsingStatementRule(Token usingToken)
   at System.Management.Automation.Language.Parser.UsingStatementsRule()

### Error details

```console
PS C:\Users\Martin> get-error

Exception             :
    Type           : System.Management.Automation.MethodInvocationException
    ErrorRecord    :
        Exception             :
            Type    : System.Management.Automation.ParentContainsErrorRecordException
            Message : Exception calling "ReadLine" with "3" argument(s): "Unrecoverable error in PowerShell."
            HResult : -2146233087
        CategoryInfo          : NotSpecified: (:) [], ParentContainsErrorRecordException
        FullyQualifiedErrorId : ParseException
        InvocationInfo        :
            ScriptLineNumber : 7
            OffsetInLine     : 5
            HistoryId        : -1
            ScriptName       : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1
            Line             : [Microsoft.PowerShell.PSConsoleReadLine]::ReadLine($host.Runspace, $ExecutionContext, $lastRunStatus)

            PositionMessage  : At C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1:7 char:5
                               +     [Microsoft.PowerShell.PSConsoleReadLine]::ReadLine($host.Runspace …
                               +     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            PSScriptRoot     : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0
            PSCommandPath    : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1
            CommandOrigin    : Internal
        ScriptStackTrace      : at PSConsoleHostReadLine, C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1: line 7
    TargetSite     :
        Name          : ConvertToMethodInvocationException
        DeclaringType : System.Management.Automation.ExceptionHandlingOps, System.Management.Automation, Version=7.2.0.10, Culture=neutral, PublicKeyToken=31bf3856ad364e35
        MemberType    : Method
        Module        : System.Management.Automation.dll
    Message        : Exception calling "ReadLine" with "3" argument(s): "Unrecoverable error in PowerShell."
    Data           : System.Collections.ListDictionaryInternal
    InnerException :
        Type           : System.Management.Automation.ParseException
        Message        : Unrecoverable error in PowerShell.
        ErrorRecord    :
            Exception             :
                Type    : System.Management.Automation.ParentContainsErrorRecordException
                Message : Unrecoverable error in PowerShell.
                HResult : -2146233087
            CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
            FullyQualifiedErrorId : Parse
        TargetSite     :
            Name          : ParseInput
            DeclaringType : System.Management.Automation.Language.Parser
            MemberType    : Method
            Module        : System.Management.Automation.dll
        InnerException :
            Type       : System.NullReferenceException
            TargetSite :
                Name          : ExtentOf
                DeclaringType : System.Management.Automation.Language.Parser
                MemberType    : Method
                Module        : System.Management.Automation.dll
            Message    : Object reference not set to an instance of an object.
            Source     : System.Management.Automation
            HResult    : -2147467261
            StackTrace :
   at System.Management.Automation.Language.Parser.ExtentOf(Token first, Ast last)
   at System.Management.Automation.Language.Parser.UsingStatementRule(Token usingToken)
   at System.Management.Automation.Language.Parser.UsingStatementsRule()
   at System.Management.Automation.Language.Parser.ScriptBlockRule(Token lCurly, Boolean isFilter, StatementAst predefinedStatementAst)
   at System.Management.Automation.Language.Parser.ParseTask(String fileName, String input, List`1 tokenList, Boolean recursed, ParseMode parseMode)
   at System.Management.Automation.Language.Parser.Parse(String fileName, String input, List`1 tokenList, ParseError[]& errors, ParseMode parseMode)
   at System.Management.Automation.Language.Parser.ParseInput(String input, String fileName, Token[]& tokens, ParseError[]& errors)
        Source         : System.Management.Automation
        HResult        : -2146233087
        StackTrace     :
   at System.Management.Automation.Language.Parser.ParseInput(String input, String fileName, Token[]& tokens, ParseError[]& errors)
   at System.Management.Automation.Language.Parser.ParseInput(String input, Token[]& tokens, ParseError[]& errors)
   at Microsoft.PowerShell.PSConsoleReadLine.ParseInput()
   at Microsoft.PowerShell.PSConsoleReadLine.GenerateRender(String defaultColor)
   at Microsoft.PowerShell.PSConsoleReadLine.ForceRender()
   at Microsoft.PowerShell.PSConsoleReadLine.Render()
   at Microsoft.PowerShell.PSConsoleReadLine.Insert(String s)
   at Microsoft.PowerShell.PSConsoleReadLine.ReadLine(Runspace runspace, EngineIntrinsics engineIntrinsics, CancellationToken cancellationToken, Nullable`1 lastRunStatus)
   at Microsoft.PowerShell.PSConsoleReadLine.ReadLine(Runspace runspace, EngineIntrinsics engineIntrinsics, Nullable`1 lastRunStatus)
   at CallSite.Target(Closure , CallSite , Type , Object , Object , Object )
    Source         : System.Management.Automation
    HResult        : -2146233087
    StackTrace     :
   at System.Management.Automation.ExceptionHandlingOps.ConvertToMethodInvocationException(Exception exception, Type typeToThrow, String methodName, Int32 numArgs, MemberInfo memberInfo)
   at CallSite.Target(Closure , CallSite , Type , Object , Object , Object )
   at System.Dynamic.UpdateDelegates.UpdateAndExecute4[T0,T1,T2,T3,TRet](CallSite site, T0 arg0, T1 arg1, T2 arg2, T3 arg3)
   at System.Management.Automation.Interpreter.DynamicInstruction`5.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
FullyQualifiedErrorId : ParseException
InvocationInfo        :
    ScriptLineNumber : 7
    OffsetInLine     : 5
    HistoryId        : -1
    ScriptName       : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1
    Line             : [Microsoft.PowerShell.PSConsoleReadLine]::ReadLine($host.Runspace, $ExecutionContext, $lastRunStatus)

    PositionMessage  : At C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1:7 char:5
                       +     [Microsoft.PowerShell.PSConsoleReadLine]::ReadLine($host.Runspace …
                       +     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    PSScriptRoot     : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0
    PSCommandPath    : C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1
    CommandOrigin    : Internal
ScriptStackTrace      : at PSConsoleHostReadLine, C:\Users\Martin\Documents\PowerShell\Modules\PSReadLine\2.2.0\PSReadLine.psm1: line 7

Environment data

PS C:\Users\Martin> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.2.0-preview.10
PSEdition                      Core
GitCommitId                    7.2.0-preview.10
OS                             Microsoft Windows 10.0.19044
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

No response

[iSazonov]

@MartinGC94 Good catch! If you want to fix I'd suggest to start with formal nullable annotations of the parser code.

🎉This issue was addressed in #16745, which has now been successfully released as v7.3.0-preview.7.:tada:

Handy links:

• Release Notes