Remove Microsoft.DotNet.PlatformAbstractions

This library overlapped with other System APIs and is now obsolete. For API replacement:

ApplicationEnvironment.ApplicationBasePath => AppContext.BaseDirectory
HashCodeCombiner => System.HashCode
RuntimeEnvironment.GetRuntimeIdentifier() => RuntimeInformation.RuntimeIdentifier
RuntimeEnvironment.OperatingSystemPlatform => RuntimeInformation.IsOSPlatform(OSPlatform)
RuntimeEnvironment.RuntimeArchitecture => RuntimeInformation.ProcessArchitecture
RuntimeEnvironment.OperatingSystem => RuntimeInformation.OSDescription
RuntimeEnvironment.OperatingSystemVersion => RuntimeInformation.OSDescription / Environment.OSVersion.Version

Fix dotnet#3470

eng/Signing.props

@@ -71,7 +71,6 @@
     <ItemsToSign Include="$(BaseOutputRootPath)corehost/**/nethost.dll" />
 
     <!-- Sign managed libraries in installer subset. -->
-    <ItemsToSign Include="$(ArtifactsBinDir)Microsoft.DotNet.PlatformAbstractions/**/*.dll" />
     <ItemsToSign Include="$(ArtifactsBinDir)Microsoft.NET.HostModel/**/*.dll" />
   </ItemGroup>
 

eng/Subsets.props

@@ -13,7 +13,7 @@
 
       ./build.sh corehost installer.managed
 
-        This builds the CoreHost and also the Managed installer portion (e.g. Microsoft.DotNet.PlatformAbstractions)
+        This builds the CoreHost and also the Managed installer portion (e.g. Microsoft.NET.HostModel)
         projects. A space ' ' or '+' are the delimiters between multiple subsets to build.
 
       ./build.sh -test installer.tests
@@ -104,7 +104,7 @@
     <!-- Installer -->
     <SubsetName Include="Installer" Description="The .NET Core hosts, hosting libraries, bundles, and installers. Includes these projects' tests." />
     <SubsetName Include="CoreHost" Description="The .NET Core hosts." />
-    <SubsetName Include="Installer.Managed" Description="The managed .NET hosting projects. This includes PlatformAbstractions and HostModel." />
+    <SubsetName Include="Installer.Managed" Description="The managed .NET hosting projects. This includes HostModel." />
     <SubsetName Include="Installer.DepProjs" Description="The dependency projects. These gather shared framework files and run crossgen on them to turn them into ready-to-run (R2R) assemblies for the current platform." />
     <SubsetName Include="Installer.PkgProjs" Description="The packaging projects. These produce NETCoreApp assets: NuGet packages, installers, zips, and Linux packages." />
     <SubsetName Include="Bundles" Description="The shared framework bundle installer projects. Produces .exe installers for Windows." />

eng/Versions.props

@@ -67,8 +67,7 @@
     <MicrosoftNETCoreAppVersion>5.0.0-preview.4.20202.18</MicrosoftNETCoreAppVersion>
     <MicrosoftNETCoreDotNetHostVersion>5.0.0-preview.4.20202.18</MicrosoftNETCoreDotNetHostVersion>
     <MicrosoftNETCoreDotNetHostPolicyVersion>5.0.0-preview.4.20202.18</MicrosoftNETCoreDotNetHostPolicyVersion>
-    <MicrosoftExtensionsDependencyModelVersion>2.1.0</MicrosoftExtensionsDependencyModelVersion>
-    <MicrosoftDotNetPlatformAbstractionsVersion>3.0.0</MicrosoftDotNetPlatformAbstractionsVersion>
+    <MicrosoftExtensionsDependencyModelVersion>3.1.0</MicrosoftExtensionsDependencyModelVersion>
     <!-- CoreClr dependencies -->
     <MicrosoftNETCoreILAsmVersion>5.0.0-preview.4.20202.18</MicrosoftNETCoreILAsmVersion>
     <MicrosoftNETSdkILVersion>5.0.0-preview.4.20202.18</MicrosoftNETSdkILVersion>

src/coreclr/src/System.Private.CoreLib/Tools/GenUnicodeProp/GenUnicodeProp.csproj

@@ -43,7 +43,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.DotNet.PlatformAbstractions" Version="$(MicrosoftDotNetPlatformAbstractionsVersion)" />
     <PackageReference Include="Microsoft.DotNet.XUnitExtensions" Version="$(MicrosoftDotNetXUnitExtensionsVersion)" />
     <PackageReference Include="xunit.core" Version="$(XUnitVersion)" ExcludeAssets="build" />
     <PackageReference Include="xunit.assert" Version="$(XUnitVersion)" />

src/installer/Microsoft.DotNet.CoreSetup.sln

@@ -9,8 +9,6 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		NuGet.Config = NuGet.Config
 	EndProjectSection
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.DotNet.PlatformAbstractions", "managed\Microsoft.DotNet.PlatformAbstractions\Microsoft.DotNet.PlatformAbstractions.csproj", "{04D84DC8-A509-43FE-B846-16B770D9E3AA}"
-EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "HostActivation.Tests", "test\HostActivation.Tests\HostActivation.Tests.csproj", "{23F4AB97-D15C-4C51-A641-DF5C5D5EF70F}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestUtils", "test\TestUtils\TestUtils.csproj", "{D6676666-D14D-4DFA-88FB-76E3E823E2E1}"
@@ -41,22 +39,6 @@ Global
 		RelWithDebInfo|x64 = RelWithDebInfo|x64
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Debug|x64.ActiveCfg = Debug|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Debug|x64.Build.0 = Debug|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.MinSizeRel|Any CPU.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.MinSizeRel|Any CPU.Build.0 = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.MinSizeRel|x64.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.MinSizeRel|x64.Build.0 = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Release|Any CPU.Build.0 = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Release|x64.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.Release|x64.Build.0 = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.RelWithDebInfo|Any CPU.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.RelWithDebInfo|Any CPU.Build.0 = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.RelWithDebInfo|x64.ActiveCfg = Release|Any CPU
-		{04D84DC8-A509-43FE-B846-16B770D9E3AA}.RelWithDebInfo|x64.Build.0 = Release|Any CPU
 		{23F4AB97-D15C-4C51-A641-DF5C5D5EF70F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{23F4AB97-D15C-4C51-A641-DF5C5D5EF70F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{23F4AB97-D15C-4C51-A641-DF5C5D5EF70F}.Debug|x64.ActiveCfg = Debug|Any CPU

src/installer/corehost/cli/hostmisc/pal.h

@@ -249,7 +249,6 @@ namespace pal
     inline void err_flush() { std::fflush(stderr); }
     inline void out_flush() { std::fflush(stdout); }
 
-    // Based upon https://github.com/dotnet/core-setup/blob/master/src/Microsoft.DotNet.PlatformAbstractions/Native/PlatformApis.cs
     string_t get_current_os_rid_platform();
     inline string_t get_current_os_fallback_rid()
     {

src/installer/managed/CommonManaged.props

@@ -16,15 +16,6 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <!-- Managed API isn't completely documented yet. TODO: https://github.com/dotnet/core-setup/issues/5108 -->
     <NoWarn>$(NoWarn);CS1591</NoWarn>
-    <!--
-      Arcade specifies a default en-US NeutralLanguage, which creates a
-      System.Resources.NeutralResourcesLanguageAttribute that doesn't compile with existing
-      references for PlatformAbstractions on netstandard1.3. Clearing NeutralLanguage removes it.
-
-      If this Arcade SDK feature is desired in the future, this will need to be worked through. No
-      issue tracks this as of writing.
-    -->
-    <NeutralLanguage></NeutralLanguage>
   </PropertyGroup>
 
   <PropertyGroup>
@@ -34,20 +25,11 @@
     <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
   </PropertyGroup>
 
-  <PropertyGroup Condition=" '$(TargetFramework)' != 'netstandard2.0' And '$(TargetFramework)' != 'netcoreapp2.0' ">
-    <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
-  </PropertyGroup>
-
   <PropertyGroup>
     <RepositoryType>git</RepositoryType>
-    <RepositoryUrl>git://github.com/dotnet/core-setup</RepositoryUrl>
+    <RepositoryUrl>git://github.com/dotnet/runtime</RepositoryUrl>
   </PropertyGroup>
 
-  <ItemGroup Condition=" '$(TargetFrameworkIdentifier)' == '.NETFramework' ">
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-  </ItemGroup>
-
   <!-- Add required legal files to packages -->
   <ItemGroup>
     <Content Condition="Exists('$(NugetLicenseFile)')"