title: What's purpose of <SolutionDir> element in .csproj file?
body: <p>My <code>.csproj</code> file contains this declaration:</p>
  
  <pre><code>  &lt;PropertyGroup&gt;
      &lt;Configuration Condition=" '$(Configuration)' == '' "&gt;Debug&lt;/Configuration&gt;
       ...
      &lt;SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'"&gt;..\&lt;/SolutionDir&gt;
    &lt;/PropertyGroup&gt;
  </code></pre>
  
  <p>My expectation was it needed to discover the solution file when you build the project directly from the project directory and don't specify <code>/p:SolutionDir=</code> parameter. However, <code>..\</code> is not automatically resolved to an absolute path and so is useless if you have solution related dependencies.</p>