Getting "Argument type 'StreamSocket' is not CLS-compliant" warning on build

Question

I'm developing a UWP library which has public properties and method parameters of StreamSocket class. However, I'm getting "StreamSocket is not CLS-compliant" warning. What's so special there that Microsoft decided to leave the respective assembly non-CLS-compliant and are there any potential issues I should know about when using/distributing this library? Maybe CLS incompliance will somehow limit the ways my library can be used by other developers?

Answer 1

Well, from the documentation:

If you design a CLS–compliant class library, your library will have a guarantee of interoperability with a wide range of programming languages; therefore, your library is likely to have a wider customer base than a version that is not CLS-compliant.

So the [obvious] answer is that they did not have "programming language interoperatibility" in mind when they coded that thing.

I am not surprised to be honest, MS is not exactly known for strictness (IE anyone?)

Read more here: https://msdn.microsoft.com/en-us/library/bhc3fa7f.aspx

UPDATE:

I will try to demystify this a little bit based on the comments.

The CLS (Common Language Specification) defines the features that any language that targets the .NET Framework MUST support. Hence, you should only care about it if your libraries are going to be consumed by a .NET language.

For instance, there is a restriction in the CLS that says that class and member names cannot differ only by case. You can't have one property named MySocket and another one named mySocket. This is important for languages like VB .NET which are not case sensitive.

In the case at hand, your library is exposing StreamSocket, which is not marked as CLS Compliant. What if this class has methods like the samples above and you try to use your library in some VB.NET project? This is what the compiler is warning you about.