dotnet/roslyn

IDE0051 should factor in new dependency attributes in .NET 5

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#48,206 opened on Sep 30, 2020

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 (9 comments) (3 reactions) (0 assignees)C# (4,257 forks)batch import
Area-IDEConcept-Continuous ImprovementFeature - IDE0051help wanted

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Description

Version Used: 3.9.0-1.20480.1+b3c3f4875957e51526000898673291d11708d35b

Steps to Reproduce:

using System;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;

class Program
{
    static void Main() => new Program().Bar();

    [DynamicDependency("Foo")]
    private void Bar() => typeof(Program).GetMethod("Foo", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(this, null);

    private void Foo() => Console.WriteLine("Hello");
}

Expected Behavior: .NET 5 adds new attributes that enable dependencies not obvious in the code, e.g. those via reflection, to be used for dead code elimination tools like https://github.com/mono/linker to better understand such dependencies. IDE0051 is such a tool and should ideally respect these attributes, such that in this example, IDE0051 doesn't fire.

Actual Behavior: IDE0051 fires and suggests deleting the "unused" method: image

cc: @eerhardt, @nickcraver

Contributor guide

Research direction
Understand the IDE0051 analyzer in the Roslyn codebase. Locate the method that detects unused private members. Add logic to respect DynamicDependency attribute. Write tests to verify the fix.
Tech stack
csharp
Domain
tooling
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.
1-2 days
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
Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50