S4261 has incorrect examples

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#1

Both the compliant and noncompliant examples are missing the async modifier for the function. That is what determines if the method should be suffixed with Async or not.

current compliant example

public class Foo
  {
    public Task ReadAsync(byte [] buffer, int offset, int count, CancellationToken cancellationToken)
  }

what it should be

public class Foo
  {
    public async Task ReadAsync(byte [] buffer, int offset, int count, CancellationToken cancellationToken) {}
  }

… though even this is strange as the method name is Read but this doesnt return the result of reading anything.

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#2

Hi @StingyJack,

Could you provide some more explanation on why you think this is the case?

Judging from the examples given in the reference in the rule description, it looks to me that async is not required at all.

However, I am not very familiar with this topic (TAP), so I might be mistaken. Maybe the examples in the reference are also incorrect?

Cheers,
Björn

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#3

I recorded an issue with the official msft docs that’s informing this rule. https://github.com/dotnet/docs/issues/22188

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#4

So what looks like is that this rule has referenced the example code that is incorrect, and not the section that states the rule.

Asynchronous methods in TAP include the Async suffix after the operation name for methods that return awaitable types, such as Task, Task, ValueTask, and ValueTask. For example, an asynchronous Get operation that returns a Task<String> can be named GetAsync

#5

Hi @StingyJack

According to the msft docs that you also cited, the method should have an Async suffix if it returns an awaitable type. The current compliant example demonstrates that. So, I would say the rule is aligned with the msft docs.

#6

The current compliant example is missing the async keyword. The presence of that keyword is what determines if the method is async or not. The return type from the function has nothing to do with async, but you can’t have an awaitable type without the async keyword.

You can also return Task and not be async. The doc page you cited has bad examples (as do many of the related pages).
see Implementing the Task-based Asynchronous Pattern | Microsoft Docs for a correct doc.

#7

Hi @StingyJack,

thanks for your feedback.

After an internal discussion we decided to deprecate the rule:

Best regards,
Costin

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#8

Thanks, I can dig that

#9

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