Creating custom analyzer in C# with mandatory string variable in all files

Question

I am trying to create a custom analyzer in C# which will ensure that we will have a string variable always declared in a class file

I have gone through a few tutorials like Building a Code Analyzer for .NET.

Is this even possible to enforce? I am trying to build my own Test Impact Analysis tools based on feature tags in spec flow. This variable will enforce declaration of my SpecFlow annotations.