Intellisense stops working when method signature contains optional parameter

Intellisense stops working when method signature contains optional parameter by DanielKzu

Closed

as Won't Fix Help for as Won't Fix

Type:	Bug
ID:	780724
Opened:	3/5/2013 12:39:57 PM
Access Restriction:	Public

Workaround(s)

view

User(s) can reproduce this bug

Generic methods that leverage the generic parameters to specify the types of expressions/lambdas received as parameters, typically work great (i.e. fluent APIs that exist everywhere) and infer the types of the lambdas and provide great intellisense.

This stops working completely when the generic method has optional parameters, though, as we just discovered :(

Details (expand)

Visual Studio 2012

namespace IntellisenseBug
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var mapper = new Mapper<FromData, ToData>();

            // NOTE: NO intellisense when the method has an optional parameter
            // Intellisense comes back for the "x." below if the optional parameter is removed.
            // mapper.Map(x => x.
        }
    }

    public class Mapper<TTypeFrom, TTypeTo>
    {
        // NOTE: remove the optional parameter and notice how you get intellisense for the x above.
        // Bring it back, and intellisense is broken automatically and the lambda no longer has intellisense for the types.
        public void Map<TPropertyFrom, TPropertyTo>(Expression<Func<TTypeFrom, TPropertyFrom>> from, Expression<Func<TTypeTo, TPropertyTo>> to, bool throwIfMissing = true)
        {
        }
    }

    public class FromData
    {
        public int Int { get; set; }
        public string String { get; set; }
    }

    public class ToData
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }
}

English

Windows 8

English

Adding the optional parameter breaks intellisense.

The optional parameter should not make a difference with regards to type inference and intellisense.

0 attachments

Posted by Microsoft on 4/16/2013 at 9:34 AM

Hi, DanielKzu. Thanks for letting us know about this. While we do not currently have plans to address this issue in the next release of Visual Studio, we do plan to fix it in Roslyn, which is our long-lead effort to rebuild the C# and VB editing experiences from the ground up. When Roslyn eventually becomes part of Visual Studio, you should see this issue corrected. We have not determined when that will be, but it is on our roadmap.

Posted by Microsoft on 3/12/2013 at 11:38 PM

Thank you for submitting feedback on Visual Studio and .NET Framework. Your issue has been routed to the appropriate VS development team for investigation. We will contact you if we require any additional information.

Posted by Microsoft on 3/5/2013 at 12:51 PM

Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com)