Understanding Roslyn Analyzers

Before we can go into what a Roslyn Analyzer is, let’s talk about Roslyn.

Roslyn is the codename for the reimagined .NET Compiler Platform that was released alongside Visual Studio 2015. Since “.NET Compiler Platform” is a lot to say, most people refer to this as the Roslyn compiler or simply Roslyn for short.

Before Roslyn, if a tool wanted to understand C#, VB, or F# source code, developers needed to write their own language parser for these code files. This involved a significant amount of time and complexity, and this effort needed to be repeated every time these programming languages changed. This led to tools being slower to support new language features, lost productivity, and bugs.

One of the explicit goals of the Rosyln compiler was to provide visibility into the structure of code in a standardized way. This way, plugins could work with the Roslyn APIs to get live information about code without having to write their...