CRR0038 - The CancellationToken parameter is never used

This analyzer detects asynchronous methods that do not use the passed CancellationToken parameter.

async Task ProcessFileAsync(string path, CancellationToken cancellationToken)
{
    var lines = await File.ReadAllLinesAsync(path).ConfigureAwait(false);
    foreach (var line in lines)
    {
        //...
    }    
}

All asynchronous methods should accept the CancellationToken parameter and use it to cancel a task if task cancellation is requested. Refer to the Task Cancellation article for more information.

async Task ProcessFileAsync(string path, CancellationToken cancellationToken)
{
    cancellationToken.ThrowIfCancellationRequested();
    var lines = await File.ReadAllLinesAsync(path, cancellationToken).ConfigureAwait(false);
    foreach (var line in lines)
    {
        cancellationToken.ThrowIfCancellationRequested();
        //...
    }    
}