VSTHRD103 is produced inside of ContinueWith when passing task.Result as an argument for async function.

[MaximTrushin]

VS 2022 v17.4.2:

Steps to Reproduce:

Try to compile the following code:

...

Task<Expr.Nullable<int>> r1 = TestAsyncDelayAsync(15).ContinueWith((Task<Expr.Nullable<int>> task) => {
    return TestAsyncDelayAsync(task.**Result**.Value + 10);
}, TaskScheduler.Default).Unwrap();

var r2 = TestAsyncDelayAsync(15).ContinueWith((Task<Expr.Nullable<int>> task) => {
                return TestDelay(task.Result.Value + 10);
            }, TaskScheduler.Default);
...
...

public async Task<Expr.Nullable<int>> TestAsyncDelayAsync(int delayMilliseconds) {
    await Task.Delay(TimeSpan.FromMilliseconds(delayMilliseconds));
    return new Expr.Nullable<int>(delayMilliseconds);
}

public Expr.Nullable<int> TestDelay(int delayMilliseconds) {
    return new Expr.Nullable<int>(delayMilliseconds);
}

The assignment to r1 produces the VSTHRD103, but the assignment to r2 doesn't.

Expected Behavior: The warning must not be produced because the task is always completed when the lambda defined in ContinueWith is called.

Actual Behavior: VSTHRD103 is produced inside of ContinueWith when passing task.Result as an argument for async function.

[AArnott]

tip, @maximtrushin: use 3 backticks in a row around your multi-line code snippets so github formats them properly. Adding a cs after the opening 3 backticks adds syntax colorization.

[AArnott]

Can you include the actual emitted warning? I'm surprised that VSTHRD103 is doing this because I thought that was the job of VSTHRD002.
In any case though, there are several ContinueWith scenarios. This one seems similar to #1123.

[MaximTrushin]

This is the emitted warning:

[VSTHRD103] Result synchronously blocks. Use await instead.

For some reason, I can't reproduce the issue when using a small console application or library assembly. I see it happening only in bigger projects.

[manfred-brands]

I still see this in version 17.11.20 and can repeat it with a small class:

namespace VSTHRD103;

public sealed class VSTHRD103
{
    public static Task<Thing> CreateAsync() => Task.FromResult(new Thing());

    public static Task<Thing> CreateWithNameAsync() => CreateAsync().ContinueWith(t => t.Result.EnsureNameAsync("Name"), TaskScheduler.Default).Unwrap();
}

public sealed class Thing
{
    public string? Name { get; private set; }

    public Task<Thing> EnsureNameAsync(string name)
    {
        Name = name;
        return Task.FromResult(this);
    }
}

[manfred-brands]

Your unit test with a ContinueWith: task.ContinueWith(t => { Console.WriteLine(t.Result); }); bails out because the method is an Action not a Func returning Task.

I don't see any code in the actual Analyzer making exemptions when called from inside a ContinueWith