VB -> C#: Interop method invocations with OptionalAttribute aren't converted

[TymurGubayev]

VB.Net input code

    Sub S()
        Dim what = Microsoft.Office.Interop.Word.WdGoToItem.wdGoToLine

        Dim objRange As Microsoft.Office.Interop.Word.Range
        objRange = objRange.GoTo(what, , -1)
        objRange = objRange.GoTo(what, Nothing, -1)
    End Sub

where the signature of the GoTo method is

    [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
    [DispId(173)]
    [return: MarshalAs(UnmanagedType.Interface)]
    Range GoTo([Optional][In][MarshalAs(UnmanagedType.Struct)] ref object What, [Optional][In][MarshalAs(UnmanagedType.Struct)] ref object Which, [Optional][In][MarshalAs(UnmanagedType.Struct)] ref object Count, [Optional][In][MarshalAs(UnmanagedType.Struct)] ref object Name);

Erroneous output

        public void S()
        {
            var what = Microsoft.Office.Interop.Word.WdGoToItem.wdGoToLine;

            var objRange = default(Microsoft.Office.Interop.Word.Range);
            object argWhat = what;
            object argCount = -1;
            objRange = default
#error Cannot convert InvocationExpressionSyntax - see comment for details
   /* Cannot convert ArgumentListSyntax, System.InvalidOperationException: Operation is not valid due to the current state of the object.
      at Microsoft.CodeAnalysis.VisualBasic.Symbols.ParameterSymbol.get_ExplicitDefaultValue()
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.CreateOptionalRefArg(IParameterSymbol p, RefKind refKind)
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.<GetAdditionalRequiredArgs>d__132.MoveNext()
      at System.Linq.Enumerable.<ConcatIterator>d__59`1.MoveNext()
      at Microsoft.CodeAnalysis.CSharp.SyntaxFactory.SeparatedList[TNode](IEnumerable`1 nodes)
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.<VisitArgumentList>d__55.MoveNext()
   --- End of stack trace from previous location where exception was thrown ---
      at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
      at ICSharpCode.CodeConverter.CSharp.CommentConvertingVisitorWrapper.<ConvertHandledAsync>d__12`1.MoveNext()

   Input: (what, , -1)

   Context:
   objRange.[GoTo](what, , -1)

    */
   ;
            what = (Microsoft.Office.Interop.Word.WdGoToItem)Conversions.ToInteger(argWhat);
            object argWhat1 = what;
            object argWhich = null;
            object argCount1 = -1;
            objRange = default
#error Cannot convert InvocationExpressionSyntax - see comment for details
   /* Cannot convert ArgumentListSyntax, System.InvalidOperationException: Operation is not valid due to the current state of the object.
      at Microsoft.CodeAnalysis.VisualBasic.Symbols.ParameterSymbol.get_ExplicitDefaultValue()
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.CreateOptionalRefArg(IParameterSymbol p, RefKind refKind)
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.<GetAdditionalRequiredArgs>d__132.MoveNext()
      at System.Linq.Enumerable.<ConcatIterator>d__59`1.MoveNext()
      at Microsoft.CodeAnalysis.CSharp.SyntaxFactory.SeparatedList[TNode](IEnumerable`1 nodes)
      at ICSharpCode.CodeConverter.CSharp.ExpressionNodeVisitor.<VisitArgumentList>d__55.MoveNext()
   --- End of stack trace from previous location where exception was thrown ---
      at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
      at ICSharpCode.CodeConverter.CSharp.CommentConvertingVisitorWrapper.<ConvertHandledAsync>d__12`1.MoveNext()

   Input: (what, Nothing, -1)

   Context:
   objRange.[GoTo](what, Nothing, -1)

    */
   ;
            what = (Microsoft.Office.Interop.Word.WdGoToItem)Conversions.ToInteger(argWhat1);
        }
    }

Expected output

public void S()
{
    var what = Microsoft.Office.Interop.Word.WdGoToItem.wdGoToLine;

    var objRange = default(Microsoft.Office.Interop.Word.Range);
    object argWhat = what;
    object argWhich = null;
    object argCount = -1;
    objRange = default
    objRange.[GoTo](what, argWhich, -1);
    what = (Microsoft.Office.Interop.Word.WdGoToItem)Conversions.ToInteger(argWhat);
    object argWhat1 = what;
    object argWhich1 = null;
    object argCount1 = -1;
    objRange = default
    objRange.[GoTo](what, argWhich1, -1);
    what = (Microsoft.Office.Interop.Word.WdGoToItem)Conversions.ToInteger(argWhat1);
}

Details

• Product in use: VS extension
• Version in use: ae25cdc
• Did you see it working in a previous version, which? No
• Any other relevant information to the issue, or your interest in contributing a fix.

[GrahamTheCoder]

Thanks for raising all these issues. I'm hoping I'll get a chance to solve a few in the next week or so, but am very happy to receive even draft PRs for any of them too

[GrahamTheCoder]

It's not quite compilable code due to the missing arg, but here's a simple way to make the library throw in the same way

Public Partial Class Foo
    Public Shared Sub Main()
        Console.WriteLine(New Foo().ExplicitFunc())
    End Sub

    Private Function ExplicitFunc(ByRef str As String) As Integer
        Return 1
    End Function
End Class