IDE0059 message is not correct for C#14 extension method

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It bothers me. A fix would be nice]

Microsoft Visual Studio Community, Channel: Insiders, Version: Insiders [11121.172]
With C# 14.

This C# console program:

Console.WriteLine("Hello, World!");

double x = 2;

x.Clamp(0, 1.5);
Console.WriteLine(x.ToString());

public static class DoubleExtensions
{

    extension(ref double number)
    {
        public void Clamp(double min, double max)
        {
            if (number < min) number = min;
            if (number > max) number = max;
        }
    }
}
  

Gives this in Error List

> Message (active) IDE0059 Avoid unnecessary value assignments in your code, as these likely indicate redundant value computations. If the value computation is not redundant and you intend to retain the assignment, then change the assignment target to a local variable whose name starts with an underscore and is optionally followed by an integer, such as ‘_’, ‘_1’, ‘_2’, etc. These are treated as special discard symbol names. Test extension ref C:\Users\gnils\source\repos\Test extension ref\Test extension ref\Program.cs 17

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Original Comments

Feedback Bot on 10/28/2025, 06:59 AM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.

Thor Yeow Dong (Centific Technologies Inc) [MSFT] on 11/10/2025, 01:15 PM:

Thank you for taking the time to log this issue!
Do you still repro this issue now? I can’t repro this issue in Visual Studio Community 2026 Insider [11201.2].
Result: The solution works find and run with no errors.

In order to investigate your issue further, can you help to confirm several questions?
1. Could you try to update your VS to latest build?
2. Did you see this issue only once or is it happening all the time?
3. Can you try to delete the .vs folder and reload this project?
4. Can you provide us a repro video using https://www.screentogif.com/ or a similar tool?
5. Could you try to repair your VS?

Gunnar Nilsson on 11/10/2025, 08:00 PM:

1. Still there in Version: Insiders [11201.2]
2. All the time.
3. Still there after .vs delete
4. Here is everything, including video Test extension ref.zip
5. Still there (repair with Visual Studio Installer)

Maybe I was unclear about, that it’s only the Error List , and only IntelliSense.
(The zip contains the hole project, Animation.gif is in the subfolder: Text extension ref)

Thor Yeow Dong (Centific Technologies Inc) [MSFT] on 11/11/2025, 05:35 AM:

Thanks for your sharing the detail steps, I can reproduce this issue through your shared steps and this issue has been escalated for further investigation, if there is any process, I will inform you immediately.

Feedback Bot on 11/19/2025, 11:03 AM:

We will close this report in 14 days because we don’t have enough information to investigate further. To keep the problem open, please provide the requested details.

Feedback Bot on 12/5/2025, 03:35 AM:

This issue is currently being investigated. Our team will get back to you if either more information is needed, a workaround is available, or the issue is resolved.

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Original Solutions

Rose Hazel Joy Bigcas (CSI INTERFUSION INC) [MSFT] solved on 12/4/2025, 00:44 PM, undefined votes:

We are unable to investigate this issue further without the additional information requested. If you are able to provide more information, you can request the issue being reactivate below. See our guidelines for further information about our process.

Gunnar Nilsson on 12/5/2025, 01:03 AM:

From Thor Yeow Dong (Centific Technologies Inc) [MSFT] reply:
Thanks for your sharing the detail steps, I can reproduce this issue through your shared steps and this issue has been escalated for further investigation, if there is any process, I will inform you immediately.