Support .NET Standard 2.0 (#672)

* Support .NET Standard 2.0

* Hide API using Index/Range
The polyfills generated by PolySharp cannot be made public as there will be conflicts with the polyfills generated by others.

* Use HashCode from Microsoft.Bcl.HashCode

---------

Co-authored-by: Stuart Turner <[email protected]>

Author: Bouke

Directory.Packages.props

@@ -9,6 +9,7 @@
 	<PackageVersion Include="coverlet.msbuild" Version="6.0.2" />
 	<PackageVersion Include="DocFx.App" Version="2.77.0" />
 	<PackageVersion Include="GitHubActionsTestLogger" Version="2.4.1" />
+	<PackageVersion Include="Microsoft.Bcl.HashCode" Version="1.1.1" />
 	<PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" />
 	<PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.10.0" />
 	<PackageVersion Include="Microsoft.CodeAnalysis.PublicApiAnalyzers" Version="3.3.4" />
@@ -17,6 +18,7 @@
 	<PackageVersion Include="MinVer" Version="5.0.0" />
 	<PackageVersion Include="Scriban" Version="5.10.0" />
 	<PackageVersion Include="System.Linq.Async" Version="6.0.1" />
+	<PackageVersion Include="System.Memory" Version="4.5.5" />
 	<PackageVersion Include="ThisAssembly.Resources" Version="1.4.3" />
 	<PackageVersion Include="xunit" Version="2.9.0" />
   </ItemGroup>
@@ -31,7 +33,6 @@
 
   <ItemGroup>
 	<GlobalPackageReference Include="Meziantou.Analyzer" Version="2.0.160" />
-	<GlobalPackageReference Include="Microsoft.CodeAnalysis.PerformanceSensitiveAnalyzers" Version="3.3.1" />
 	<GlobalPackageReference Include="PolySharp" Version="1.14.1" />
   </ItemGroup>
 </Project>

Source/SuperLinq.Async/ElementAt.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -101,3 +103,5 @@ CancellationToken cancellationToken
 		return (false, default);
 	}
 }
+
+#endif

Source/SuperLinq.Async/FindIndex.cs

@@ -1,3 +1,5 @@
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -202,3 +204,5 @@ CancellationToken cancellationToken
 		}
 	}
 }
+
+#endif

Source/SuperLinq.Async/FindLastIndex.cs

@@ -1,3 +1,5 @@
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -187,3 +189,5 @@ CancellationToken cancellationToken
 		}
 	}
 }
+
+#endif

Source/SuperLinq.Async/GetShortestPath.cs

@@ -812,7 +812,7 @@ public partial class AsyncSuperEnumerable
 			var queue = new UpdatablePriorityQueue<TState, (TState? parent, TCost? cost)>(
 				16,
 				priorityComparer: Comparer<(TState? parent, TCost? cost)>.Create(
-					(x, y) => costComparer.Compare(x.cost, y.cost)),
+					(x, y) => costComparer.Compare(x.cost!, y.cost!)),
 				stateComparer);
 
 			var current = start;
@@ -1154,7 +1154,7 @@ public partial class AsyncSuperEnumerable
 				cancellationToken.ThrowIfCancellationRequested();
 
 				if (!totalCost.TryGetValue(current, out var oldCost)
-					|| costComparer.Compare(costs.traversed, oldCost) < 0)
+					|| costComparer.Compare(costs.traversed!, oldCost!) < 0)
 				{
 					totalCost[current] = costs.traversed;
 					if (await predicate(current).ConfigureAwait(false))
@@ -1503,7 +1503,7 @@ public partial class AsyncSuperEnumerable
 				cancellationToken.ThrowIfCancellationRequested();
 
 				if (!totalCost.TryGetValue(current, out var oldCost)
-					|| costComparer.Compare(from.traversed, oldCost.traversed) < 0)
+					|| costComparer.Compare(from.traversed!, oldCost.traversed!) < 0)
 				{
 					totalCost[current] = (from.parent, from.traversed);
 					if (await predicate(current).ConfigureAwait(false))

Source/SuperLinq.Async/IAsyncBuffer.cs

@@ -1,4 +1,4 @@
-namespace SuperLinq.Async;
+namespace SuperLinq.Async;
 
 /// <summary>
 /// Represents a cached sequence that can be re-enumerated multiple times.
@@ -20,6 +20,7 @@ public interface IAsyncBuffer<out T> : IAsyncEnumerable<T>, IAsyncDisposable
 	/// </summary>
 	int Count { get; }
 
+#if NETCOREAPP
 	/// <summary>
 	///		Configures how awaits on the tasks returned from an async disposable are performed.
 	/// </summary>
@@ -31,4 +32,5 @@ public interface IAsyncBuffer<out T> : IAsyncEnumerable<T>, IAsyncDisposable
 	/// </returns>
 	public ConfiguredAsyncDisposable ConfigureAwait(bool continueOnCapturedContext) =>
 		((IAsyncDisposable)this).ConfigureAwait(continueOnCapturedContext);
+#endif
 }

Source/SuperLinq.Async/IndexOf.cs

@@ -1,3 +1,5 @@
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -126,3 +128,5 @@ public static ValueTask<int> IndexOf<TSource>(
 		return FindIndex(source, i => EqualityComparer<TSource>.Default.Equals(i, item), index, count, cancellationToken);
 	}
 }
+
+#endif

Source/SuperLinq.Async/Insert.cs

@@ -1,3 +1,5 @@
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -136,3 +138,5 @@ static async IAsyncEnumerable<T> Core(
 		}
 	}
 }
+
+#endif

Source/SuperLinq.Async/Join.MergeJoin.cs

@@ -722,6 +722,10 @@ file sealed class ComparerEqualityComparer<TKey>(
 	IComparer<TKey> comparer
 ) : IEqualityComparer<TKey>
 {
-	public bool Equals([AllowNull] TKey x, [AllowNull] TKey y) => comparer.Compare(x, y) == 0;
+	public bool Equals([AllowNull] TKey x, [AllowNull] TKey y) => comparer.Compare(x!, y!) == 0;
+#if NETCOREAPP
 	public int GetHashCode([DisallowNull] TKey obj) => ThrowHelper.ThrowNotSupportedException<int>();
+#else
+	public int GetHashCode(TKey obj) => ThrowHelper.ThrowNotSupportedException<int>();
+#endif
 }

Source/SuperLinq.Async/LastIndexOf.cs

@@ -1,3 +1,5 @@
+#if !NO_INDEX
+
 namespace SuperLinq.Async;
 
 public static partial class AsyncSuperEnumerable
@@ -135,3 +137,5 @@ public static ValueTask<int> LastIndexOf<TSource>(
 		);
 	}
 }
+
+#endif

Source/SuperLinq.Async/PublicAPI/netstandard2.0/PublicAPI.Shipped.txt

@@ -0,0 +1 @@
+#nullable enable