Add System.IO.Hashing ref csproj (#77856)

* Add System.IO.Hashing ref csproj

* Fix System.IO.Hashing ref source and add sln

Author: stephentoub

eng/ApiCompatExcludeAttributes.txt

@@ -2,3 +2,4 @@ T:System.Diagnostics.CodeAnalysis.MemberNotNullAttribute
 T:System.Diagnostics.DebuggerGuidedStepThroughAttribute
 T:System.Runtime.CompilerServices.EagerStaticClassConstructionAttribute
 T:System.Runtime.CompilerServices.NativeIntegerAttribute
+T:System.Runtime.CompilerServices.SkipLocalsInitAttribute

src/libraries/System.IO.Hashing/System.IO.Hashing.sln

@@ -1,6 +1,8 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestUtilities", "..\Common\tests\TestUtilities\TestUtilities.csproj", "{F94DE827-A426-45CB-AE6E-4E1C154B5386}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Hashing", "ref\System.IO.Hashing.csproj", "{259A1DB6-EF7E-4D45-96EF-035E0605BB55}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Hashing", "src\System.IO.Hashing.csproj", "{A078A4EB-27E8-42B1-BD44-3807732A4560}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.IO.Hashing.Tests", "tests\System.IO.Hashing.Tests.csproj", "{2E6DAC1B-9054-40AF-AF72-4C2DD7BD9294}"
@@ -9,6 +11,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "LibraryImportGenerator", ".
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.Interop.SourceGeneration", "..\System.Runtime.InteropServices\gen\Microsoft.Interop.SourceGeneration\Microsoft.Interop.SourceGeneration.csproj", "{A60C1BBE-8CD7-4B6A-AD3C-FF1209857C39}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "ref", "ref", "{46BA9FAE-9204-455A-BB2D-518E5B5C3E4C}"
+EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{1E78399D-326B-4C9F-B8A9-A7E684EEA349}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{F2826BE8-9FA1-40C8-8FD4-E98A4644733E}"
@@ -25,6 +29,10 @@ Global
 		{F94DE827-A426-45CB-AE6E-4E1C154B5386}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{F94DE827-A426-45CB-AE6E-4E1C154B5386}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{F94DE827-A426-45CB-AE6E-4E1C154B5386}.Release|Any CPU.Build.0 = Release|Any CPU
+		{259A1DB6-EF7E-4D45-96EF-035E0605BB55}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{259A1DB6-EF7E-4D45-96EF-035E0605BB55}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{259A1DB6-EF7E-4D45-96EF-035E0605BB55}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{259A1DB6-EF7E-4D45-96EF-035E0605BB55}.Release|Any CPU.Build.0 = Release|Any CPU
 		{A078A4EB-27E8-42B1-BD44-3807732A4560}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{A078A4EB-27E8-42B1-BD44-3807732A4560}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A078A4EB-27E8-42B1-BD44-3807732A4560}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -48,6 +56,7 @@ Global
 	GlobalSection(NestedProjects) = preSolution
 		{F94DE827-A426-45CB-AE6E-4E1C154B5386} = {1E78399D-326B-4C9F-B8A9-A7E684EEA349}
 		{2E6DAC1B-9054-40AF-AF72-4C2DD7BD9294} = {1E78399D-326B-4C9F-B8A9-A7E684EEA349}
+		{259A1DB6-EF7E-4D45-96EF-035E0605BB55} = {46BA9FAE-9204-455A-BB2D-518E5B5C3E4C}
 		{A078A4EB-27E8-42B1-BD44-3807732A4560} = {F2826BE8-9FA1-40C8-8FD4-E98A4644733E}
 		{0EBDAC1E-7132-406B-96B4-F8875A689C99} = {26D7BA38-5978-4423-814C-0C8D9F38C1A3}
 		{A60C1BBE-8CD7-4B6A-AD3C-FF1209857C39} = {26D7BA38-5978-4423-814C-0C8D9F38C1A3}

src/libraries/System.IO.Hashing/ref/System.IO.Hashing.cs

@@ -44,11 +44,26 @@ public void Append(System.IO.Stream stream) { }
         public byte[] GetHashAndReset() { throw null; }
         public int GetHashAndReset(System.Span<byte> destination) { throw null; }
         protected virtual void GetHashAndResetCore(System.Span<byte> destination) { }
+        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
+        [System.ObsoleteAttribute("Use GetCurrentHash() to retrieve the computed hash code.", true)]
         public override int GetHashCode() { throw null; }
         public abstract void Reset();
         public bool TryGetCurrentHash(System.Span<byte> destination, out int bytesWritten) { throw null; }
         public bool TryGetHashAndReset(System.Span<byte> destination, out int bytesWritten) { throw null; }
     }
+    public sealed partial class XxHash3 : System.IO.Hashing.NonCryptographicHashAlgorithm
+    {
+        public XxHash3() : base (default(int)) { }
+        public XxHash3(long seed) : base (default(int)) { }
+        public override void Append(System.ReadOnlySpan<byte> source) { }
+        protected override void GetCurrentHashCore(System.Span<byte> destination) { }
+        public static byte[] Hash(byte[] source) { throw null; }
+        public static byte[] Hash(byte[] source, long seed) { throw null; }
+        public static byte[] Hash(System.ReadOnlySpan<byte> source, long seed = (long)0) { throw null; }
+        public static int Hash(System.ReadOnlySpan<byte> source, System.Span<byte> destination, long seed = (long)0) { throw null; }
+        public override void Reset() { }
+        public static bool TryHash(System.ReadOnlySpan<byte> source, System.Span<byte> destination, out int bytesWritten, long seed = (long)0) { throw null; }
+    }
     public sealed partial class XxHash32 : System.IO.Hashing.NonCryptographicHashAlgorithm
     {
         public XxHash32() : base (default(int)) { }

src/libraries/System.IO.Hashing/ref/System.IO.Hashing.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <NoWarn>$(NoWarn);CS0809</NoWarn>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="System.IO.Hashing.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+    <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
+  </ItemGroup>
+</Project>