Re-enable UAP builds (dotnet/corefx#27531)

* Build uapaot System.Numerics.Vectors

With `Vector<T>` now residing in System.Private.CoreLib, directly reference System.Private.Corelib instead of contracts just like netcoreapp does.

Add uapaot flavor since System.Private.CoreLib has a different strong name key on that platform.

* Make EnsureExtendedPrefixOverMaxPath available to UAP

Add the helper method `System.IO.PathInternal.EnsureExtendedPrefixOverMaxPath` to Common\src\System\IO\PathInternal.Windows.cs. It was previously not visible to UAP since  Common\src\CoreLib\System\IO\PathInternal.Windows.cs is not included in UAP compilation.

* Keep SocketsHttpHandler out of UAP builds

SocketsHttpHandler is not supported in uap and is currently leaking into UAP builds since they've been disabled for a few weeks. Adjust the contract so it's not available to UAP, and clean the implementation assembly so SocketsHttpHandler internals don't leak out into HttpClientHandler.Core.cs.

* Fix GetAddrInfoExSupportsOverlapped UAP build break

`System.Net.NameResolutionPal.GetAddrInfoExSupportsOverlapped` uses LoadLibraryExW which is not compatible with UAP (which only supports LoadLibrary of DLLs within a container). Refactor the helper so UAP returns false.

* Revert "Disable UAP legs per dotnet/corefx#26802 (dotnet/corefx#26822)"

This reverts commit dotnet/corefx@120dce4.

* Revert "Disable UAP configurations in all configurations build"

This reverts commit dotnet/corefx@2202b4f.

* Revert "Disable UAP official builds (dotnet/corefx#26871)"

This reverts commit dotnet/corefx@ef79caf.

- Baseline the ApiCompat and GenFacades failures in System.Runtime.Extensions and System.Threading.ThreadPool.
- Adjust naming of files to match branch conventions
- Fix up some configuration issues with uap packaging. The CoreFX.Private.TestUtilities packaging needs updated build tools which can map between uwp6.0 and netstandard2.0.
- ifdef out Thread.GetCurrentProcessorId until we get a new System.Private.CoreLib.


Commit migrated from dotnet/corefx@c9cdfba

src/libraries/Common/src/Interop/Windows/kernel32/Interop.CreateFile2.cs

@@ -92,7 +92,7 @@ internal unsafe static IntPtr CreateFile_IntPtr(
             FileMode dwCreationDisposition,
             int dwFlagsAndAttributes)
         {
-            lpFileName = PathInternal.EnsureExtendedPrefixOverMaxPath(lpFileName);
+            lpFileName = PathInternal.EnsureExtendedPrefixIfNeeded(lpFileName);
             return CreateFile(lpFileName, dwDesiredAccess, dwShareMode, null, dwCreationDisposition, dwFlagsAndAttributes, IntPtr.Zero);
         }
     }

src/libraries/CoreFx.Private.TestUtilities/ref/CoreFx.Private.TestUtilities.csproj

@@ -6,7 +6,7 @@
     <ShouldWriteSigningRequired>false</ShouldWriteSigningRequired>
     <AllowReferenceFromRuntime>true</AllowReferenceFromRuntime>
     <RuntimeProjectFile>$(ProjectDir)\external\test-runtime\XUnit.Runtime.depproj</RuntimeProjectFile>
-    <PackageTargetFramework>netstandard2.0</PackageTargetFramework> 
+    <PackageTargetFramework>netstandard2.0;$(UAPvNextTFM)</PackageTargetFramework>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard-Release|AnyCPU'" />

src/libraries/System.IO.Pipes.AccessControl/src/Configurations.props

@@ -1,12 +1,15 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
-    <BuildConfigurations>
+    <PackageConfigurations>
       netfx-Windows_NT;
       netcoreapp-Windows_NT;
-      uap-Windows_NT;
       netstandard-Windows_NT;
       netstandard;
+    </PackageConfigurations>
+    <BuildConfigurations>
+      $(PackageConfigurations);
+      uap-Windows_NT;
     </BuildConfigurations>
   </PropertyGroup>
-</Project>
+</Project> 

src/libraries/System.Net.Http/ref/System.Net.Http.cs

@@ -236,6 +236,7 @@ public ReadOnlyMemoryContent(System.ReadOnlyMemory<byte> content) { }
         protected override System.Threading.Tasks.Task SerializeToStreamAsync(System.IO.Stream stream, System.Net.TransportContext context) => throw null;
         protected internal override bool TryComputeLength(out long length) => throw null;
     }
+#if !uap
     public sealed class SocketsHttpHandler : HttpMessageHandler
     {
         public SocketsHttpHandler() { }
@@ -261,6 +262,7 @@ public SocketsHttpHandler() { }
         protected override void Dispose(bool disposing) { }
         protected internal override System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage> SendAsync(System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) { throw null; }
     }
+#endif
     public partial class StreamContent : System.Net.Http.HttpContent
     {
         public StreamContent(System.IO.Stream content) { }

src/libraries/System.Net.Http/ref/System.Net.Http.csproj

@@ -3,6 +3,7 @@
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
   <PropertyGroup>
     <ProjectGuid>{132BF813-FC40-4D39-8B6F-E55D7633F0ED}</ProjectGuid>
+    <DefineConstants Condition="'$(TargetGroup)' == 'uap'">$(DefineConstants);uap</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Release|AnyCPU'" />

src/libraries/System.Net.Http/src/System.Net.Http.csproj

@@ -55,7 +55,6 @@
     <Compile Include="System\Net\Http\MultipartFormDataContent.cs" />
     <Compile Include="System\Net\Http\NetEventSource.Http.cs" />
     <Compile Include="System\Net\Http\ReadOnlyMemoryContent.cs" />
-    <Compile Include="System\Net\Http\SocketsHttpHandler\HttpAuthenticatedConnectionHandler.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpConnectionKind.cs" />
     <Compile Include="System\Net\Http\StreamContent.cs" />
     <Compile Include="System\Net\Http\StreamToStreamCopy.cs" />
@@ -139,6 +138,7 @@
     <Compile Include="System\Net\Http\SocketsHttpHandler\CookieHelper.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\DecompressionHandler.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\EmptyReadStream.cs" />
+    <Compile Include="System\Net\Http\SocketsHttpHandler\HttpAuthenticatedConnectionHandler.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpConnection.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpConnectionHandler.cs" />
     <Compile Include="System\Net\Http\SocketsHttpHandler\HttpConnectionPool.cs" />
@@ -359,6 +359,7 @@
   <!-- WinHttpHandler implementation -->
   <ItemGroup Condition=" '$(TargetsWindows)' == 'true' And '$(TargetGroup)' != 'uap'">
     <Compile Include="System\Net\Http\HttpClientHandler.Core.cs" />
+    <Compile Include="System\Net\Http\HttpClientHandler.netcoreapp.cs" />
     <Compile Include="System\Net\Http\HttpClientHandler.Windows.cs" />
   </ItemGroup>
   <!-- Compile the WinHttpHandler implementation into the System.Net.Http.dll binary.  This is a
@@ -381,6 +382,7 @@
   </PropertyGroup>
   <ItemGroup Condition=" '$(TargetsUnix)' == 'true' ">
     <Compile Include="System\Net\Http\HttpClientHandler.Core.cs" />
+    <Compile Include="System\Net\Http\HttpClientHandler.netcoreapp.cs" />
     <Compile Include="System\Net\Http\HttpClientHandler.Unix.cs" />
     <Compile Include="System\Net\Http\CurlHandler\CurlHandler.cs" />
     <Compile Include="System\Net\Http\CurlHandler\CurlHandler.EasyRequest.cs" />

src/libraries/System.Net.Http/src/System/Net/Http/HttpClientHandler.Core.cs

@@ -62,12 +62,5 @@ private void CheckDisposedOrStarted()
                 throw new InvalidOperationException(SR.net_http_operation_started);
             }
         }
-
-        private void ThrowForModifiedManagedSslOptionsIfStarted()
-        {
-            // Hack to trigger an InvalidOperationException if a property that's stored on
-            // SslOptions is changed, since SslOptions itself does not do any such checks.
-            _socketsHttpHandler.SslOptions = _socketsHttpHandler.SslOptions;
-        }
     }
 }

src/libraries/System.Net.Http/src/System/Net/Http/HttpClientHandler.netcoreapp.cs

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Net.Security;
+using System.Security.Authentication;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace System.Net.Http
+{
+    // This partial implementation contains members common to NetCoreApp
+    public partial class HttpClientHandler : HttpMessageHandler
+    {
+        private void ThrowForModifiedManagedSslOptionsIfStarted()
+        {
+            // Hack to trigger an InvalidOperationException if a property that's stored on
+            // SslOptions is changed, since SslOptions itself does not do any such checks.
+            _socketsHttpHandler.SslOptions = _socketsHttpHandler.SslOptions;
+        }
+    }
+}

src/libraries/System.Net.NameResolution/src/System.Net.NameResolution.csproj

@@ -54,6 +54,8 @@
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetsWindows)' == 'true'">
     <Compile Include="System\Net\NameResolutionPal.Windows.cs" />
+    <Compile Include="System\Net\NameResolutionPal.Win32.cs" Condition="'$(TargetGroup)' != 'uap'"/>
+    <Compile Include="System\Net\NameResolutionPal.Uap.cs" Condition="'$(TargetGroup)' == 'uap'"/>
     <Compile Include="$(CommonPath)\System\Net\ContextAwareResult.Windows.cs">
       <Link>Common\System\Net\ContextAwareResult.Windows.cs</Link>
     </Compile>
@@ -126,13 +128,13 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.GetAddrInfoExW.cs">
       <Link>Interop\Windows\Winsock\Interop.GetAddrInfoExW.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)\Microsoft\Win32\SafeHandles\SafeLibraryHandle.cs">
+    <Compile Include="$(CommonPath)\Microsoft\Win32\SafeHandles\SafeLibraryHandle.cs" Condition="'$(TargetGroup)' != 'uap'">
       <Link>Common\Microsoft\Win32\SafeHandles\SafeLibraryHandle.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.GetProcAddress.cs">
+    <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.GetProcAddress.cs" Condition="'$(TargetGroup)' != 'uap'">
       <Link>Interop\Windows\Kernel32\Interop.GetProcAddress.cs</Link>
     </Compile>
-    <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.LoadLibraryEx.cs">
+    <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.LoadLibraryEx.cs" Condition="'$(TargetGroup)' != 'uap'">
       <Link>Interop\Windows\Kernel32\Interop.LoadLibraryEx.cs</Link>
     </Compile>
     <Compile Include="$(CommonPath)\Interop\Windows\Kernel32\Interop.FreeLibrary.cs">

src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Uap.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Net
+{
+    internal static partial class NameResolutionPal
+    {
+        private static bool GetAddrInfoExSupportsOverlapped() => false;
+    }
+}

src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Win32.cs

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.Win32.SafeHandles;
+
+namespace System.Net
+{
+    internal static partial class NameResolutionPal
+    {
+        private static bool GetAddrInfoExSupportsOverlapped()
+        {
+            using (SafeLibraryHandle libHandle = Interop.Kernel32.LoadLibraryExW(Interop.Libraries.Ws2_32, IntPtr.Zero, Interop.Kernel32.LOAD_LIBRARY_SEARCH_SYSTEM32))
+            {
+                if (libHandle.IsInvalid)
+                    return false;
+
+                // We can't just check that 'GetAddrInfoEx' exists, because it existed before supporting overlapped.
+                // The existence of 'GetAddrInfoExCancel' indicates that overlapped is supported.
+                return Interop.Kernel32.GetProcAddress(libHandle, Interop.Winsock.GetAddrInfoExCancelFunctionName) != IntPtr.Zero;
+            }
+        }
+    }
+}

src/libraries/System.Net.NameResolution/src/System/Net/NameResolutionPal.Windows.cs

@@ -13,7 +13,7 @@
 
 namespace System.Net
 {
-    internal static class NameResolutionPal
+    internal static partial class NameResolutionPal
     {
         //
         // used by GetHostName() to preallocate a buffer for the call to gethostname.
@@ -339,19 +339,6 @@ public static void EnsureSocketsAreInitialized()
             }
         }
 
-        private static bool GetAddrInfoExSupportsOverlapped()
-        {
-            using (SafeLibraryHandle libHandle = Interop.Kernel32.LoadLibraryExW(Interop.Libraries.Ws2_32, IntPtr.Zero, Interop.Kernel32.LOAD_LIBRARY_SEARCH_SYSTEM32))
-            {
-                if (libHandle.IsInvalid)
-                    return false;
-
-                // We can't just check that 'GetAddrInfoEx' exists, because it existed before supporting overlapped.
-                // The existance of 'GetAddrInfoExCancel' indicates that overlapped is supported.
-                return Interop.Kernel32.GetProcAddress(libHandle, Interop.Winsock.GetAddrInfoExCancelFunctionName) != IntPtr.Zero;
-            }
-        }
-
         public static unsafe void GetAddrInfoAsync(DnsResolveAsyncResult asyncResult)
         {
             GetAddrInfoExContext* context = GetAddrInfoExContext.AllocateContext();

src/libraries/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj

@@ -56,14 +56,20 @@
     <Compile Include="$(CommonTestPath)\System\Net\Configuration.Http.cs">
       <Link>Common\System\Net\Configuration.Http.cs</Link>
     </Compile>
-	<Compile Include="$(CommonPath)\System\Net\ByteOrder.cs">
+    <Compile Include="$(CommonPath)\System\Net\ByteOrder.cs">
       <Link>Common\System\Net\ByteOrder.cs</Link>
     </Compile>
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetsWindows)' == 'true' ">
     <Compile Include="..\..\src\System\Net\NameResolutionPal.Windows.cs">
       <Link>ProductionCode\System\Net\NameResolutionPal.Windows.cs</Link>
     </Compile>
+    <Compile Include="..\..\src\System\Net\NameResolutionPal.Uap.cs" Condition="'$(TargetGroup)' == 'uap'">
+      <Link>ProductionCode\System\Net\NameResolutionPal.Uap.cs</Link>
+    </Compile>
+    <Compile Include="..\..\src\System\Net\NameResolutionPal.Win32.cs" Condition="'$(TargetGroup)' == 'netcoreapp'">
+      <Link>ProductionCode\System\Net\NameResolutionPal.Win32.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\System\Net\InternalException.cs">
       <Link>Common\System\Net\InternalException.cs</Link>
     </Compile>
@@ -73,7 +79,7 @@
     <Compile Include="$(CommonPath)\System\Net\SocketProtocolSupportPal.Windows.cs">
       <Link>System\Net\SocketProtocolSupportPal.Windows</Link>
     </Compile>
-	<Compile Include="$(CommonPath)\System\Net\SocketAddressPal.Windows.cs">
+    <Compile Include="$(CommonPath)\System\Net\SocketAddressPal.Windows.cs">
       <Link>Common\System\Net\SocketAddressPal.Windows</Link>
     </Compile>
     <!-- Debug only -->

src/libraries/System.Numerics.Vectors/ref/Configurations.props

@@ -9,6 +9,7 @@
     <BuildConfigurations>
       netcoreapp;
       uap;
+      uapaot;
       netfx;
       $(PackageConfigurations);
     </BuildConfigurations>

src/libraries/System.Numerics.Vectors/ref/System.Numerics.Vectors.csproj

@@ -17,6 +17,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard1.0-Release|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uap-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uap-Release|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uapaot-Debug|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uapaot-Release|AnyCPU'" />
   <ItemGroup>
     <Compile Include="System.Numerics.Vectors.cs" />
   </ItemGroup>
@@ -27,7 +29,7 @@
   <ItemGroup Condition="'$(TargetGroup)' == 'netstandard1.0'">
     <Reference Include="System.Runtime" />
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetGroup)' == 'netcoreapp' OR '$(TargetGroup)' == 'uap'">
+  <ItemGroup Condition="'$(TargetGroup)' == 'netcoreapp' OR '$(TargetGroup)' == 'uap' OR '$(TargetGroup)' == 'uapaot'">
     <ProjectReference Include="..\..\System.Runtime\ref\System.Runtime.csproj" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />

src/libraries/System.Numerics.Vectors/src/Configurations.props

@@ -7,6 +7,7 @@
       net46;
     </PackageConfigurations>
     <BuildConfigurations>
+      uapaot-Windows_NT;
       uap-Windows_NT;
       netfx-Windows_NT;
       netcoreapp-Windows_NT;

src/libraries/System.Numerics.Vectors/src/System.Numerics.Vectors.csproj

@@ -7,7 +7,7 @@
     <DocumentationFile>$(OutputPath)$(MSBuildProjectName).xml</DocumentationFile>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IsTargetingNetFx Condition="'$(TargetGroup)'=='netfx' OR '$(TargetGroup)'=='net46'">true</IsTargetingNetFx>
-    <IsTargetingNetCoreApp Condition="'$(TargetGroup)'=='netcoreapp'">true</IsTargetingNetCoreApp>
+    <IsTargetingNetCoreApp Condition="'$(TargetGroup)'=='netcoreapp' OR '$(TargetGroup)'=='uap' OR '$(TargetGroup)'=='uapaot'">true</IsTargetingNetCoreApp>
     <IsPartialFacadeAssembly Condition="'$(IsTargetingNetFx)'=='true' OR '$(IsTargetingNetCoreApp)'=='true'">true</IsPartialFacadeAssembly>
     <PackageTargetFramework Condition="'$(TargetGroup)' == 'netstandard1.0'">netstandard1.0;portable-net45+win8+wp8+wpa81</PackageTargetFramework>
   </PropertyGroup>
@@ -25,6 +25,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard1.0-Release|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uap-Windows_NT-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uap-Windows_NT-Release|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uapaot-Windows_NT-Debug|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'uapaot-Windows_NT-Release|AnyCPU'" />
   <!-- Shared -->
   <ItemGroup>
     <Compile Include="$(CommonPath)\System\Numerics\Hashing\HashHelpers.cs">

src/libraries/System.Runtime.Extensions/src/ApiCompatBaseline.uapaot.txt

@@ -0,0 +1,5 @@
+TypesMustExist : Type 'System.Globalization.GlobalizationExtensions' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.IO.Path.Join(System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.IO.Path.Join(System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.IO.Path.TryJoin(System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>, System.Span<System.Char>, System.Int32)' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'System.IO.Path.TryJoin(System.ReadOnlySpan<System.Char>, System.ReadOnlySpan<System.Char>, System.Span<System.Char>, System.Int32)' does not exist in the implementation but it does exist in the contract.

src/libraries/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj

@@ -10,6 +10,7 @@
     <IncludeDllSafeSearchPathAttribute>true</IncludeDllSafeSearchPathAttribute>
     <DefineConstants Condition="'$(TargetGroup)' == 'uapaot'">$(DefineConstants);uapaot</DefineConstants>
     <ILLinkClearInitLocals>true</ILLinkClearInitLocals>
+    <GenFacadesIgnoreMissingTypes Condition="'$(TargetGroup)'=='uapaot'">true</GenFacadesIgnoreMissingTypes>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Unix-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Unix-Release|AnyCPU'" />

src/libraries/System.Threading.Thread/src/System.Threading.Thread.csproj

@@ -6,6 +6,7 @@
     <OutputType>Library</OutputType>
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
     <ProjectGuid>{06197EED-FF48-43F3-976D-463839D43E8C}</ProjectGuid>
+    <DefineConstants Condition="'$(TargetGroup)' == 'uapaot'">$(DefineConstants);uapaot</DefineConstants>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Unix-Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Unix-Release|AnyCPU'" />

src/libraries/System.Threading.Thread/src/System/Threading/Thread.cs

@@ -272,7 +272,15 @@ public void SetCompressedStack(CompressedStack stack)
             throw new InvalidOperationException(SR.Thread_GetSetCompressedStack_NotSupported);
         }
 
+#if uapaot
+        //
+        // Todo: Remove when we update System.Private.CoreLib for uapaot
+        // https://github.com/dotnet/corefx/issues/27619
+        //
+        public static int GetCurrentProcessorId() => 0;
+#else
         public static int GetCurrentProcessorId() => RuntimeThread.GetCurrentProcessorId();
+#endif
         public static AppDomain GetDomain() => AppDomain.CurrentDomain;
         public static int GetDomainID() => GetDomain().Id;
         public override int GetHashCode() => ManagedThreadId;

src/libraries/System.Threading.ThreadPool/src/ApiCompatBaseline.uapaot.txt

@@ -0,0 +1 @@
+MembersMustExist : Member 'System.Threading.ThreadPool.QueueUserWorkItem<TState>(System.Action<TState>, TState, System.Boolean)' does not exist in the implementation but it does exist in the contract.