dotnet/roslyn

Asynchronous methods and variables not showing unused warning

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#52,328 opened on Apr 1, 2021

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 (7 comments) (1 reaction) (0 assignees)C# (4,257 forks)batch import
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Description

Version Used: Version 16.9.0 Preview 3.0

Steps to Reproduce:

  1. Set a variable to an asynchronous await call var root = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false))

  2. Do not use the variable

  3. Create an asynchronous method

  4. Do not call the asynchronous method

Expected Behavior: Green underline appears underneath root and method header name indicating that the variable/method is unused.

Actual Behavior: The unused warning does not appear.

Note: I may be missing an option selection that would make it so the warning appears in this case, but I am unsure.

Contributor guide

Research direction
Investigate how Roslyn's unused variable analysis handles async/await patterns. Look at the flow analysis for 'await' expressions and method invocations. Check if there are existing tests for unused async variables or methods.
Tech stack
csharp
Domain
compilersdeveloper experience
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.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#async/awaitRoslyn APIs
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40