Walk the #line

Program.Original.cs

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string foobar = _s("$foo$ bar", new { foo = Foo() }), baz = Baz();
        }

        static string Foo() { return "Foo"; }
        static string Baz() { return "Baz"; }
    }
}

Program.Rewritten.Badly.cs

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string _s_123 = string.Concat(Foo(), " bar");
            string foobar = _s_123, baz = Baz();
        }

        static string Foo() { return "Foo"; }
        static string Baz() { return "Baz"; }
    }
}

Program.Rewritten.cs

#line 1 "Program.Original.cs"
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
#line hidden
            string _s_123 = string.Concat(Foo(), " bar");
#line 7
            string foobar = _s_123                              ,
#line 7
                                                                  baz = Baz();
        }

        static string Foo() { return "Foo"; }
        static string Baz() { return "Baz"; }
    }
}