Awesome

Meziantou.Polyfill

Source Generator that adds polyfill methods and types. This helps working with multi-targeted projects.

Read more about the project: Polyfills in .NET to ease multi-targeting

Installation

dotnet add package Meziantou.Polyfill

Then, you should see the generated types in the solution explorer

Generated files in the Visual Studio's Solution Explorer

Customization

By default, all needed polyfills are generated. You can configure which polyfills should be generated by editing the .csproj file and adding the following properties:

<PropertyGroup>
  <!-- semicolon-separated or pipe-separated list of name prefix -->
  <!-- Tip: The name of the generated polyfills are available in the generated "Debug.g.cs" file -->
  <MeziantouPolyfill_IncludedPolyfills>T:Type1|T:Type2|M:Member1</MeziantouPolyfill_IncludedPolyfills>
  <MeziantouPolyfill_ExcludedPolyfills>M:System.Diagnostics.</MeziantouPolyfill_ExcludedPolyfills>

  <!-- Optional: Output the generated files to the obj\GeneratedFiles folder  -->
  <EmitCompilerGeneratedFiles>True</EmitCompilerGeneratedFiles>
  <CompilerGeneratedFilesOutputPath>$(BaseIntermediateOutputPath)\GeneratedFiles</CompilerGeneratedFilesOutputPath>
</PropertyGroup>

Supported polyfills

Types

System.Collections.Generic.PriorityQueue<TElement, TPriority>
System.Collections.Generic.ReferenceEqualityComparer
System.Diagnostics.CodeAnalysis.AllowNullAttribute
System.Diagnostics.CodeAnalysis.DisallowNullAttribute
System.Diagnostics.CodeAnalysis.DoesNotReturnAttribute
System.Diagnostics.CodeAnalysis.DoesNotReturnIfAttribute
System.Diagnostics.CodeAnalysis.DynamicDependencyAttribute
System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes
System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute
System.Diagnostics.CodeAnalysis.ExperimentalAttribute
System.Diagnostics.CodeAnalysis.MaybeNullAttribute
System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute
System.Diagnostics.CodeAnalysis.MemberNotNullAttribute
System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute
System.Diagnostics.CodeAnalysis.NotNullAttribute
System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute
System.Diagnostics.CodeAnalysis.NotNullWhenAttribute
System.Diagnostics.CodeAnalysis.RequiresAssemblyFilesAttribute
System.Diagnostics.CodeAnalysis.RequiresDynamicCodeAttribute
System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute
System.Diagnostics.CodeAnalysis.SetsRequiredMembersAttribute
System.Diagnostics.CodeAnalysis.StringSyntaxAttribute
System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute
System.Diagnostics.CodeAnalysis.UnscopedRefAttribute
System.Diagnostics.StackTraceHiddenAttribute
System.HashCode
System.Index
System.Net.Http.ReadOnlyMemoryContent
System.Range
System.Runtime.CompilerServices.AsyncMethodBuilderAttribute
System.Runtime.CompilerServices.CallerArgumentExpressionAttribute
System.Runtime.CompilerServices.CollectionBuilderAttribute
System.Runtime.CompilerServices.CompilerFeatureRequiredAttribute
System.Runtime.CompilerServices.DisableRuntimeMarshallingAttribute
System.Runtime.CompilerServices.InterpolatedStringHandlerArgumentAttribute
System.Runtime.CompilerServices.InterpolatedStringHandlerAttribute
System.Runtime.CompilerServices.IsExternalInit
System.Runtime.CompilerServices.ModuleInitializerAttribute
System.Runtime.CompilerServices.OverloadResolutionPriorityAttribute
System.Runtime.CompilerServices.RequiredMemberAttribute
System.Runtime.CompilerServices.SkipLocalsInitAttribute
System.Runtime.CompilerServices.TupleElementNamesAttribute
System.Runtime.InteropServices.SuppressGCTransitionAttribute
System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute
System.Runtime.Versioning.ObsoletedOSPlatformAttribute
System.Runtime.Versioning.RequiresPreviewFeaturesAttribute
System.Runtime.Versioning.SupportedOSPlatformAttribute
System.Runtime.Versioning.SupportedOSPlatformGuardAttribute
System.Runtime.Versioning.TargetPlatformAttribute
System.Runtime.Versioning.UnsupportedOSPlatformAttribute
System.Runtime.Versioning.UnsupportedOSPlatformGuardAttribute
System.Threading.Lock
System.Threading.Tasks.TaskToAsyncResult
System.ValueTuple
System.ValueTuple<T1>
System.ValueTuple<T1, T2>
System.ValueTuple<T1, T2, T3>
System.ValueTuple<T1, T2, T3, T4>
System.ValueTuple<T1, T2, T3, T4, T5>
System.ValueTuple<T1, T2, T3, T4, T5, T6>
System.ValueTuple<T1, T2, T3, T4, T5, T6, T7>
System.ValueTuple<T1, T2, T3, T4, T5, T6, T7, TRest> where TRest : struct
System.ITupleInternal

Methods

System.Collections.Concurrent.ConcurrentDictionary<TKey, TValue>.GetOrAdd<TArg>(TKey key, System.Func<TKey, TArg, TValue> valueFactory, TArg factoryArgument) where TArg : allows ref struct
System.Collections.Generic.CollectionExtensions.GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key)
System.Collections.Generic.CollectionExtensions.GetValueOrDefault<TKey, TValue>(this System.Collections.Generic.IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, TValue defaultValue)
System.Collections.Generic.KeyValuePair<TKey, TValue>.Deconstruct(out TKey key, out TValue value)
System.Collections.Generic.Queue<T>.TryDequeue(out T result)
System.Collections.Immutable.ImmutableArray<T>.AsSpan()
System.Collections.Immutable.ImmutableArray<T>.AsSpan(System.Int32 start, System.Int32 length)
System.Collections.Immutable.ImmutableArray<T>.AsSpan(System.Range range)
System.Diagnostics.Process.WaitForExitAsync([System.Threading.CancellationToken cancellationToken = default])
System.IO.Stream.Read(System.Span<System.Byte> buffer)
System.IO.Stream.ReadAsync(System.Memory<System.Byte> buffer, [System.Threading.CancellationToken cancellationToken = default])
System.IO.Stream.ReadAtLeast(System.Span<System.Byte> buffer, System.Int32 minimumBytes, [System.Boolean throwOnEndOfStream = true])
System.IO.Stream.ReadAtLeastAsync(System.Memory<System.Byte> buffer, System.Int32 minimumBytes, [System.Boolean throwOnEndOfStream = true], [System.Threading.CancellationToken cancellationToken = default])
System.IO.Stream.Write(System.ReadOnlySpan<System.Byte> buffer)
System.IO.Stream.WriteAsync(System.ReadOnlyMemory<System.Byte> buffer, [System.Threading.CancellationToken cancellationToken = default])
System.IO.StreamReader.ReadLineAsync()
System.IO.StreamReader.ReadLineAsync(System.Threading.CancellationToken cancellationToken)
System.IO.TextReader.ReadAsync(System.Memory<System.Char> buffer, [System.Threading.CancellationToken cancellationToken = default])
System.IO.TextReader.ReadToEndAsync(System.Threading.CancellationToken cancellationToken)
System.IO.TextWriter.WriteAsync(System.ReadOnlyMemory<System.Char> buffer, [System.Threading.CancellationToken cancellationToken = default])
System.Linq.Enumerable.AggregateBy<TSource, TKey, TAccumulate>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TKey, TAccumulate> seedSelector, System.Func<TAccumulate, TSource, TAccumulate> func, [System.Collections.Generic.IEqualityComparer<TKey>? keyComparer = null]) where TKey : notnull
System.Linq.Enumerable.AggregateBy<TSource, TKey, TAccumulate>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, TAccumulate seed, System.Func<TAccumulate, TSource, TAccumulate> func, [System.Collections.Generic.IEqualityComparer<TKey>? keyComparer = null]) where TKey : notnull
System.Linq.Enumerable.CountBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, [System.Collections.Generic.IEqualityComparer<TKey>? keyComparer = null]) where TKey : notnull
System.Linq.Enumerable.DistinctBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector)
System.Linq.Enumerable.DistinctBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer)
System.Linq.Enumerable.Index<TSource>(this System.Collections.Generic.IEnumerable<TSource> source)
System.Linq.Enumerable.MaxBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector)
System.Linq.Enumerable.MaxBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Collections.Generic.IComparer<TKey>? comparer)
System.Linq.Enumerable.MinBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector)
System.Linq.Enumerable.MinBy<TSource, TKey>(this System.Collections.Generic.IEnumerable<TSource> source, System.Func<TSource, TKey> keySelector, System.Collections.Generic.IComparer<TKey>? comparer)
System.Linq.Enumerable.OrderDescending<T>(this System.Collections.Generic.IEnumerable<T> source)
System.Linq.Enumerable.OrderDescending<T>(this System.Collections.Generic.IEnumerable<T> source, System.Collections.Generic.IComparer<T>? comparer)
System.Linq.Enumerable.Order<T>(this System.Collections.Generic.IEnumerable<T> source)
System.Linq.Enumerable.Order<T>(this System.Collections.Generic.IEnumerable<T> source, System.Collections.Generic.IComparer<T>? comparer)
System.Linq.Enumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source)
System.Linq.Enumerable.ToHashSet<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, System.Collections.Generic.IEqualityComparer<TSource>? comparer)
System.Linq.Enumerable.Zip<TFirst, TSecond>(this System.Collections.Generic.IEnumerable<TFirst> first, System.Collections.Generic.IEnumerable<TSecond> second)
System.MemoryExtensions.AsSpan(this System.String? text, System.Int32 start, System.Int32 length)
System.MemoryExtensions.CommonPrefixLength<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> other)
System.MemoryExtensions.CommonPrefixLength<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> other, System.Collections.Generic.IEqualityComparer<T>? comparer)
System.MemoryExtensions.CommonPrefixLength<T>(this System.Span<T> span, System.ReadOnlySpan<T> other)
System.MemoryExtensions.CommonPrefixLength<T>(this System.Span<T> span, System.ReadOnlySpan<T> other, System.Collections.Generic.IEqualityComparer<T>? comparer)
System.MemoryExtensions.ContainsAnyExcept<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> values) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.ReadOnlySpan<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.ReadOnlySpan<T> span, T value0, T value1) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.ReadOnlySpan<T> span, T value0, T value1, T value2) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.Span<T> span, System.ReadOnlySpan<T> values) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.Span<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.Span<T> span, T value0, T value1) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAnyExcept<T>(this System.Span<T> span, T value0, T value1, T value2) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAny<T>(this System.Span<T> span, System.ReadOnlySpan<T> values) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAny<T>(this System.Span<T> span, T value0, T value1) where T : System.IEquatable<T>?
System.MemoryExtensions.ContainsAny<T>(this System.Span<T> span, T value0, T value1, T value2) where T : System.IEquatable<T>?
System.MemoryExtensions.Contains<T>(this System.ReadOnlySpan<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.Contains<T>(this System.Span<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> values) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.ReadOnlySpan<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.ReadOnlySpan<T> span, T value0, T value1) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.ReadOnlySpan<T> span, T value0, T value1, T value2) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.Span<T> span, System.ReadOnlySpan<T> values) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.Span<T> span, T value) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.Span<T> span, T value0, T value1) where T : System.IEquatable<T>?
System.MemoryExtensions.IndexOfAnyExcept<T>(this System.Span<T> span, T value0, T value1, T value2) where T : System.IEquatable<T>?
System.Net.Http.HttpContent.CopyTo(System.IO.Stream stream, System.Net.TransportContext? context, System.Threading.CancellationToken cancellationToken)
System.Net.Http.HttpContent.CopyToAsync(System.IO.Stream stream)
System.Net.Http.HttpContent.CopyToAsync(System.IO.Stream stream, System.Net.TransportContext? context)
System.Net.Http.HttpContent.CopyToAsync(System.IO.Stream stream, System.Net.TransportContext? context, System.Threading.CancellationToken cancellationToken)
System.Net.Http.HttpContent.CopyToAsync(System.IO.Stream stream, System.Threading.CancellationToken cancellationToken)
System.Net.Http.HttpContent.ReadAsStream(System.Threading.CancellationToken cancellationToken)
System.Net.Http.HttpContent.ReadAsStream()
System.Net.Sockets.UdpClient.Send(System.ReadOnlySpan<System.Byte> datagram, System.Net.IPEndPoint? endPoint)
System.Net.Sockets.UdpClient.Send(System.ReadOnlySpan<System.Byte> datagram, System.String? hostname, System.Int32 port)
System.Net.Sockets.UdpClient.SendAsync(System.ReadOnlyMemory<System.Byte> datagram, System.Net.IPEndPoint? endPoint, [System.Threading.CancellationToken cancellationToken = default])
System.Net.Sockets.UdpClient.SendAsync(System.ReadOnlyMemory<System.Byte> datagram, System.String? hostname, System.Int32 port, [System.Threading.CancellationToken cancellationToken = default])
System.Net.Sockets.UdpClient.SendAsync(System.ReadOnlyMemory<System.Byte> datagram, [System.Threading.CancellationToken cancellationToken = default])
System.String.Contains(System.Char value)
System.String.Contains(System.Char value, System.StringComparison comparisonType)
System.String.Contains(System.String value, System.StringComparison comparisonType)
System.String.CopyTo(System.Span<System.Char> destination)
System.String.EndsWith(System.Char value)
System.String.GetHashCode(System.StringComparison comparisonType)
System.String.IndexOf(System.Char value, System.StringComparison comparisonType)
System.String.Replace(System.String oldValue, System.String? newValue, System.StringComparison comparisonType)
System.String.ReplaceLineEndings(System.String replacementText)
System.String.ReplaceLineEndings()
System.String.Split(System.Char separator, System.Int32 count, [System.StringSplitOptions options = System.StringSplitOptions.None])
System.String.Split(System.Char separator, [System.StringSplitOptions options = System.StringSplitOptions.None])
System.String.StartsWith(System.Char value)
System.String.TryCopyTo(System.Span<System.Char> destination)
System.Text.Encoding.GetString(System.ReadOnlySpan<System.Byte> bytes)
System.Text.StringBuilder.Append(System.ReadOnlyMemory<System.Char> value)
System.Text.StringBuilder.Append(System.ReadOnlySpan<System.Char> value)
System.Text.StringBuilder.AppendJoin(System.Char separator, params System.Object?[] values)
System.Text.StringBuilder.AppendJoin(System.Char separator, params System.String?[] values)
System.Text.StringBuilder.AppendJoin(System.String? separator, params System.Object?[] values)
System.Text.StringBuilder.AppendJoin(System.String? separator, params System.String?[] values)
System.Text.StringBuilder.AppendJoin<T>(System.Char separator, System.Collections.Generic.IEnumerable<T> values)
System.Text.StringBuilder.AppendJoin<T>(System.String? separator, System.Collections.Generic.IEnumerable<T> values)
System.Text.StringBuilder.Replace(System.ReadOnlySpan<System.Char> oldValue, System.ReadOnlySpan<System.Char> newValue)
System.Text.StringBuilder.Replace(System.ReadOnlySpan<System.Char> oldValue, System.ReadOnlySpan<System.Char> newValue, System.Int32 startIndex, System.Int32 count)
System.Threading.CancellationTokenSource.CancelAsync()
System.Threading.Tasks.Task.WaitAsync(System.Threading.CancellationToken cancellationToken)
System.Threading.Tasks.TaskAsyncEnumerableExtensions.ToBlockingEnumerable<T>(this System.Collections.Generic.IAsyncEnumerable<T> source, [System.Threading.CancellationToken cancellationToken = default])
System.Type.IsAssignableTo(System.Type? targetType)

Contribution

How to add a new polyfill

Create a new file named <xml documentation id>.cs in the project Meziantou.Polyfill.Editor
Run Meziantou.Polyfill.Generator

Notes:

All files must be self contained. Use a file class if needed.
If you need to generate a file only when another polyfill is generated, add // when <xml documentation id> in the file