Error CS0234: The type or namespace name ‘Specialized’ does not exist in the namespace ‘System.Collections’
Industrial Logic’s eLearning has a feature where students can upload their programming exercise and get automated, personalized feedback. We do various server-side analysis (automated critique) of the student’s code to score them and to give them feedback about how well they performed in their programming exercises. To do this we need to compile their code on our server.
Recently we upgraded our .Net Compiler from version 2.0 to version 3.5. In version 2.0 we had to provide a reference to System.dll file (located in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\System.dll) for compiling. In version 3.5, they don’t have System.dll file. It was replaced by System.core.dll (located in c:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Core.dll)
After making this change, when we ran the compiler using c:\WINDOWS\Microsoft.NET\Framework\v3.5\Csc.exe we got the following error:
Microsoft (R) Visual C# 2008 Compiler version 3.5.30729.1
for Microsoft (R) .NET Framework version 3.5
Copyright (C) Microsoft Corporation. All rights reserved.
SomeCSharpClass.cs: error CS0234: The type or namespace name ‘Specialized’ does not exist in the namespace ‘System.Collections’ (are you missing an assembly reference?)
It turns out that ‘System.collections.specialized’ namespace used to exist in System.dll in .net 2.0. In 3.5 System.Core.dll (which replaced the System.dll) does not contain it. Hence the compile time error.
We’ve fixed this issue by adding both System.Core.dll (v3.5) and System.dll (v2.0) to the compiler reference path. Not sure if this is the right thing to do. But it seems to work.