Ix 5.0

The Ix 5.0 release shipped on November 10, 2020 as part of the .NET 5.0 release wave.

Changes:

The query operators in System.Linq.Async now support the C# 8.0 nullable reference types feature. For example, the DefaultIfEmpty operator now has the following signature:

public static IAsyncEnumerable<TSource?> DefaultIfEmpty<TSource>(this IAsyncEnumerable<TSource> source)

The implementation of query operators in System.Linq.Async now uses [EnumeratorCancellation] attributes on local functions to support the cancellation of an enumeration. This also reduces the number of heap allocations caused by query operators.