EnvDTE.CodeElement.GetStartPoint(vsCMPartBody)/GetEndPoint(vsCMPartBody) throw COMException for expression-bodied methods and properties

[carlos-quintero]

Version Used: Visual Studio 2017 15.2 (26430.16 Release)

Steps to Reproduce:

1. Create a VS package extension with a command that executes this code:

      private void MenuItemCallback(object sender, EventArgs e)
      {
         EnvDTE.DTE dte;

         dte = this.ServiceProvider.GetService(typeof(EnvDTE.DTE)) as EnvDTE.DTE;

         ShowCodeElements(dte.ActiveDocument.ProjectItem.FileCodeModel.CodeElements);
      }

      private void ShowCodeElements(EnvDTE.CodeElements codeElements)
      {
         foreach (EnvDTE.CodeElement codeElement in codeElements)
         {
            switch (codeElement)
            {
               case EnvDTE.CodeNamespace codeNamespace:

                  ShowCodeElements(codeNamespace.Members);
                  break;

               case EnvDTE.CodeType codeType:

                  ShowCodeElements(codeType.Members);
                  break;

               case EnvDTE.CodeProperty codeProperty:

                  GetPoints(codeElement);
                  break;

               case EnvDTE.CodeFunction codeFunction:

                  GetPoints(codeElement);
                  break;
            }
         }
      }

      private void GetPoints(EnvDTE.CodeElement codeElement)
      {
         System.Text.StringBuilder sb = new System.Text.StringBuilder();

         sb.AppendLine(codeElement.Name);
         sb.AppendLine();

         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartWholeWithAttributes);
         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartWhole);
         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartHeaderWithAttributes);
         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartHeader);
         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartName);
         GetPoints(sb, codeElement, EnvDTE.vsCMPart.vsCMPartBody);

         VsShellUtilities.ShowMessageBox(
             this.ServiceProvider,
             sb.ToString(),
             "",
             OLEMSGICON.OLEMSGICON_INFO,
             OLEMSGBUTTON.OLEMSGBUTTON_OK,
             OLEMSGDEFBUTTON.OLEMSGDEFBUTTON_FIRST);
      }

      private void GetPoints(System.Text.StringBuilder sb, EnvDTE.CodeElement codeElement, EnvDTE.vsCMPart part)
      {
         GetStartPoint(sb, codeElement, part);
         GetEndPoint(sb, codeElement, part);
         sb.AppendLine();
      }

      private void GetStartPoint(System.Text.StringBuilder sb, EnvDTE.CodeElement codeElement, EnvDTE.vsCMPart part)
      {
         EnvDTE.TextPoint textPoint;

         sb.Append(part.ToString() + " Start: ");

         try
         {
            textPoint = codeElement.GetStartPoint(part);
            sb.AppendLine(textPoint.Line.ToString() + ", " + textPoint.DisplayColumn.ToString());
         }
         catch (Exception ex)
         {
            sb.AppendLine(ex.GetType().Name);
         }
      }

      private void GetEndPoint(System.Text.StringBuilder sb, EnvDTE.CodeElement codeElement, EnvDTE.vsCMPart part)
      {
         EnvDTE.TextPoint textPoint;

         sb.Append(part.ToString() + " End: ");

         try
         {
            textPoint = codeElement.GetEndPoint(part);
            sb.AppendLine(textPoint.Line.ToString() + ", " + textPoint.DisplayColumn.ToString());
         }
         catch (Exception ex)
         {
            sb.AppendLine(ex.GetType().Name);
         }
      }

2. In the Experimental instance, create a Class Library with this code:

namespace ClassLibrary1
{
   public class Class1
   {
      public int f1()
      {
         return 0;
      }

      public int p1
      {
         get
         {
            return 0;
         }
      }

      public int f2() => 0;

      public int p2 => 0;
   }
}

3. Ensure that the code file is the active window and click the command of the extension

Expected Behavior: it is already bad that so many points throw NotImplementedException, but for expression-bodied members a COMException is returned when the part is vsCMPartBody.

Actual Behavior: at the very least, NotImplementedException should be returned instead of COMException. And even better, return actual information since there is a body and for regular members the body points are returned.

[Pilchie]

See also https://developercommunity.visualstudio.com/content/problem/56238/envdte-in-v152-does-not-provide-startpointendpoint.html