dotnet/roslyn

Immediate/watch window not formatting DateTimes inside loops

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#33,130 opened on Feb 5, 2019

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Area-InteractiveBugInteractive-Debugginghelp wanted

Description

Version Used: Visual Studio 2019 Preview 2

🔗 Originally filed as https://devdiv.visualstudio.com/DevDiv/_workitems/edit/215428

Steps to Reproduce:

using System;
using System.Linq;

namespace ConsoleApp1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var dt = new DateTime(2016, 3, 2);
            var result = Enumerable.Range(1, 1).Select(x => dt.ToString("yyyy")).First();
            Console.WriteLine(result);
        }
    }
}

  1. Set a breakpoint on the line with Console.WriteLine

  2. When the breakpoint is hit, observe the value of result

  3. In the Immediate window, run the following:

    Enumerable.Range(1, 1).Select(x => dt.ToString("yyyy")).First()

Expected Behavior:

Step (2) and (3) produce "2016".

Actual Behavior:

Step (2) produces "2016".

Step (3) produces "3/2/2016 12:00:00 AM".

Contributor guide

Tech stack
csharp
Domain
developer experiencetooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C#Debugging basicsRoslyn expression evaluator
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Examine the Roslyn debugger's expression evaluator code, particularly how it formats DateTime values in the Immediate window. Look for discrepancies between direct evaluation and lambda based evaluation. Focus on files in the Interactive Window or Debugger components that handle expression formatting. Check if there are any existing tests for DateTime formatting in this context.