Interactive session errors on references to system assemblies in C# script

[atifaziz]

What steps will reproduce the problem?

Create an empty LINQPad query file named Empty.linq then compile and run it as follows from a Windows Command Prompt (assuming current directory is same as where the query file is saved):

lpless  -t csx Empty.linq && Empty

The script should run without errors and emit a blank line. The compiled Empty.csx will look as follows:

#r "System.dll"
#r "Microsoft.CSharp.dll"
#r "System.Core.dll"
#r "System.Data.dll"
#r "System.Data.Entity.dll"
#r "System.Transactions.dll"
#r "System.Xml.dll"
#r "System.Xml.Linq.dll"
#r "System.Data.Linq.dll"
#r "System.Drawing.dll"
#r "System.Data.DataSetExtensions.dll"

using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Threading;
using System.Reflection;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Data;
using System.Data.SqlClient;
using System.Data.Linq;
using System.Data.Linq.SqlClient;
using System.Transactions;
using System.Xml;
using System.Xml.Linq;
using System.Xml.XPath;
System.Console.WriteLine(

);

Run a C# Interactive 2.0 (csi.exe) session and copy the content of the compiled Empty.csx above and paste it into the session.

What is the expected output? What do you see instead?

Expected the session to have the same behavior as running the script via the batch (Empty.cmd). Instead, the session emits errors for references to all system assemblies except System.dll:

Microsoft (R) Visual C# Interactive Compiler version 2.0.0.61501
Copyright (C) Microsoft Corporation. All rights reserved.

Type "#help" for more information.
> #r "System.dll"
> #r "Microsoft.CSharp.dll"
(1,1): error CS0006: Metadata file 'Microsoft.CSharp.dll' could not be found
> #r "System.Core.dll"
(1,1): error CS0006: Metadata file 'System.Core.dll' could not be found
> #r "System.Data.dll"
(1,1): error CS0006: Metadata file 'System.Data.dll' could not be found
> #r "System.Data.Entity.dll"
(1,1): error CS0006: Metadata file 'System.Data.Entity.dll' could not be found
> #r "System.Transactions.dll"
(1,1): error CS0006: Metadata file 'System.Transactions.dll' could not be found
> #r "System.Xml.dll"
(1,1): error CS0006: Metadata file 'System.Xml.dll' could not be found
> #r "System.Xml.Linq.dll"
(1,1): error CS0006: Metadata file 'System.Xml.Linq.dll' could not be found
> #r "System.Data.Linq.dll"
(1,1): error CS0006: Metadata file 'System.Data.Linq.dll' could not be found
> #r "System.Drawing.dll"
(1,1): error CS0006: Metadata file 'System.Drawing.dll' could not be found
> #r "System.Data.DataSetExtensions.dll"
(1,1): error CS0006: Metadata file 'System.Data.DataSetExtensions.dll' could not be found
>
> using System;
> using System.IO;
> using System.Text;
> using System.Text.RegularExpressions;
> using System.Diagnostics;
> using System.Threading;
> using System.Reflection;
> using System.Collections;
> using System.Collections.Generic;
> using System.Linq;
> using System.Linq.Expressions;
> using System.Data;
(1,14): error CS0234: The type or namespace name 'Data' does not exist in the namespace 'System' (are you missing an assembly reference?)
> using System.Data.SqlClient;
(1,14): error CS0234: The type or namespace name 'Data' does not exist in the namespace 'System' (are you missing an assembly reference?)
> using System.Data.Linq;
(1,14): error CS0234: The type or namespace name 'Data' does not exist in the namespace 'System' (are you missing an assembly reference?)
> using System.Data.Linq.SqlClient;
(1,14): error CS0234: The type or namespace name 'Data' does not exist in the namespace 'System' (are you missing an assembly reference?)
> using System.Transactions;
(1,14): error CS0234: The type or namespace name 'Transactions' does not exist in the namespace 'System' (are you missing an assembly reference?)
> using System.Xml;
> using System.Xml.Linq;
(1,18): error CS0234: The type or namespace name 'Linq' does not exist in the namespace 'System.Xml' (are you missing an assembly reference?)
> using System.Xml.XPath;
> System.Console.WriteLine(
.
. );

[atifaziz]

Removing the .dll extension gets rid of the errors in an interactive session:

Microsoft (R) Visual C# Interactive Compiler version 2.0.0.61501
Copyright (C) Microsoft Corporation. All rights reserved.

Type "#help" for more information.
> #r "System"
> #r "Microsoft.CSharp"
> #r "System.Core"
> #r "System.Data"
> #r "System.Data.Entity"
> #r "System.Transactions"
> #r "System.Xml"
> #r "System.Xml.Linq"
> #r "System.Data.Linq"
> #r "System.Drawing"
> #r "System.Data.DataSetExtensions"
>
> using System;
> using System.IO;
> using System.Text;
> using System.Text.RegularExpressions;
> using System.Diagnostics;
> using System.Threading;
> using System.Reflection;
> using System.Collections;
> using System.Collections.Generic;
> using System.Linq;
> using System.Linq.Expressions;
> using System.Data;
> using System.Data.SqlClient;
> using System.Data.Linq;
> using System.Data.Linq.SqlClient;
> using System.Transactions;
> using System.Xml;
> using System.Xml.Linq;
> using System.Xml.XPath;
> System.Console.WriteLine(
.
. );

Arguably, this is a C# Interactive issue as well since it has different behavior when running a script versus when issuing the content of the script in an interactive session.

[atifaziz]

C# Interactive issue reported to Roslyn (see dotnet/roslyn#18497). Hopefully this won't need any action on our end so putting it on hold.