title: How to get solution path in .NET code analyzer
body: <p>How do you get access the file path to the project/solution being compiled inside a Roslyn code analyzer? I need to verify the code against some spec files stored relative to the code. Things that do NOT work:</p>
  
  <pre><code>SyntaxTreeAnalysisContext.Tree.FilePath
  Assembly.GetExecutingAssembly().Location
  AppDomain.CurrentDomain.BaseDirectory
  Environment.CurrentDirectory
  Path.GetFullPath(relativePath)
  </code></pre>