Do not call Task.WaitAll with a single argument

[terrajobst]

Task.Wait can be used instead.

Category: Performance

[jeffhandley]

Estimates:

• Analyzer: Small
• Fixer: Small

[Mrnikbobjeff]

I have a working analyzer for this as well, if this is ready to implement. #33806 is very similar, my analyzer would offer a great basis for that issue.

[carlossanlop]

Here is a usage example:

using System.Threading.Tasks;

namespace MyNamespace
{
    class Sample
    {
        public static void Main()
        {
            Task task = ...;

            // Instead of this
            Task.WaitAll(task);

            // Suggest this
            task.Wait();

            
            // Instead of this
            Task.WaitAll(GetTask());

            // Suggest this
            GetTask().Wait();
        }

        static Task GetTask()
        {
            return ...;
        }
    }
}

• This analyzer should not affect any of the other WaitAll overloads, because they take a Task[]. Only this overload, which takes a params Task[] task would be affected.
• This analyzer should also have a fixer.
• Suggested severity: Info.
• Suggested milestone if approved: 6.0 (seems simple to address).

Questions

• Should we group this proposal with Do not call Task.WhenAll with a single argument #33806 (same but for WhenAll) into a single rule ID?

[terrajobst]

Video

• Makes sense

void M(Task task)
{
    // Before
    Task.WaitAll(task);

    // After
    task.Wait();
}

[ryzngard]

I'll take this and #33806

[carlossanlop]

It's yours, @ryzngard. Thanks for your help! Let us know if you have any questions.

[stephentoub]

This was implemented as CA1842/1843. Thanks!