dotnet/roslyn

Unclear CS0252 (Possible unintended reference comparison)

Open

#58,996 opened on Jan 21, 2022

View on GitHub
 (0 comments) (0 reactions) (0 assignees)C# (4,257 forks)batch import
Area-CompilersBugConcept-Diagnostic Clarityhelp wanted

Repository metrics

Stars
 (20,414 stars)
PR merge metrics
 (Avg merge 6d 17h) (256 merged PRs in 30d)

Description

Version Used:

17.1.0 P1.1

Steps to Reproduce:

using System;

public class C
{
    public void M(Action x, Action y)
    {
        _ = (MulticastDelegate)x == y;
    }
}

Expected Behavior:

Either no warning, or a more clear warning.

Actual Behavior:

warning CS0252: Possible unintended reference comparison; to get a value comparison, cast the left hand side to type 'MulticastDelegate'

Contributor guide

Research direction
Investigate the pattern of CS0252 warning emission in the Roslyn compiler's diagnostics engine, focusing on why it fires for a cast to MulticastDelegate and whether the warning message can be improved or suppressed for such cases.
Tech stack
csharp
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50