From c8503d39053f9e0d94716a23c406b66f126ca259 Mon Sep 17 00:00:00 2001
From: Viktor Hofer <viktor.hofer@microsoft.com>
Date: Tue, 22 Nov 2022 20:01:29 +0100
Subject: [PATCH] Cleanup GenFacades logic and don't bind against non-shipping
 contract assemblies (#78703)

* Clean-up the ApiCompat and GenAPI logic

* Fix System.DirectoryServices.AccountManagement build

System.DirectoryServices.AccountManagement now builds against
src/System.DirectoryServices instead of ref/System.DirectoryServices
(because the package doesn't contain the ref assembly).

Because of that, the compiler now gets confused because of the
System.DirectoryServices.Interop namespace and the global Interop class.
This happens even though the DirectoryServices.Interop namespace doesn't include any
public types.

That results in the following erros:
src\libraries\System.DirectoryServices.AccountManagement\src\System\DirectoryServices\AccountManagement\AD\SidList.cs(50,26): error CS0246: The type or namespace name 'SID_AND_ATTRIBUTES' could not be found (are you missing a using directive or an assembly reference?)
src\libraries\System.DirectoryServices.AccountManagement\src\System\DirectoryServices\AccountManagement\interopt.cs(439,20): error CS0246: The type or namespace name 'UNICODE_INTPTR_STRING' could not be found (are you missing a using directive or an assembly reference?)

This commit fixes that by removing the System.DirectoryServices.Interop
namespace and moving the types into the parent namespace.

* Suppress nullable warnings in Serialization.Schema

Now that Schema compiles against the source assembly of System.CodeDom,
it receives nullability errors. I'm suppressing them manually for now
but am filing an issue to correctly fix those.

Related: https://github.com/dotnet/runtime/issues/78036

* Move SkipUseReferenceAssembly target up
---
 eng/Version.Details.xml                       |   4 +-
 eng/Versions.props                            |   2 +-
 eng/references.targets                        |  20 +++
 eng/resolveContract.props                     |  14 --
 eng/resolveContract.targets                   | 128 ++++++++++--------
 .../System.Private.CoreLib.csproj             |   3 +-
 .../src/System.Private.CoreLib.csproj         |   3 +-
 src/libraries/Directory.Build.props           |   2 +-
 src/libraries/Directory.Build.targets         |  11 +-
 .../src/ILLink/ILLink.Suppressions.xml        |   2 +-
 .../src/Interop/AdsOptions.cs                 |   2 +-
 .../src/Interop/AdsPropertyOperation.cs       |   2 +-
 .../src/Interop/AdsSearchColumn.cs            |   2 +-
 .../src/Interop/AdsSearchPreferenceInfo.cs    |   2 +-
 .../src/Interop/AdsSearchPreferences.cs       |   2 +-
 .../src/Interop/AdsSortKey.cs                 |   2 +-
 .../src/Interop/AdsType.cs                    |   2 +-
 .../src/Interop/AdsValue2.cs                  |   2 +-
 .../src/Interop/AdsValueHelper2.cs            |   2 +-
 .../src/Interop/NativeMethods.cs              |   2 +-
 .../src/Interop/SafeNativeMethods.cs          |   2 +-
 .../src/Interop/UnsafeNativeMethods.cs        |   2 +-
 .../ActiveDirectory/DomainController.cs       |   2 +-
 .../DirectoryServices/AuthenticationTypes.cs  |   2 -
 .../DirectoryServices/DirectoryEntries.cs     |   1 -
 .../DirectoryServices/DirectoryEntry.cs       |   1 -
 .../DirectoryEntryConfiguration.cs            |   1 -
 .../DirectoryServices/DirectorySearcher.cs    |   1 -
 .../DirectoryServicesCOMException.cs          |   1 -
 .../DirectoryServices/PropertyCollection.cs   |   1 -
 .../PropertyValueCollection.cs                |   1 -
 .../DirectoryServices/SchemaNameCollection.cs |   1 -
 .../SearchResultCollection.cs                 |   1 -
 .../Serialization/Schema/CodeExporter.cs      |  16 +--
 src/libraries/apicompat/ApiCompat.proj        |   9 +-
 src/libraries/shims/Directory.Build.targets   |  18 ++-
 src/libraries/shims/src/Directory.Build.props |   7 -
 src/libraries/shims/src/netstandard.csproj    |   2 +-
 .../System.Private.CoreLib.csproj             |   3 +-
 39 files changed, 147 insertions(+), 134 deletions(-)
 delete mode 100644 eng/resolveContract.props

diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 8f1419c12ac43..8f89d99d6daf1 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -106,9 +106,9 @@
       <Uri>https://github.com/dotnet/arcade</Uri>
       <Sha>80b6be47e1425ea90c5febffac119250043a0c92</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.GenFacades" Version="8.0.0-beta.22554.2">
+    <Dependency Name="Microsoft.DotNet.GenFacades" Version="8.0.0-beta.22572.2">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>80b6be47e1425ea90c5febffac119250043a0c92</Sha>
+      <Sha>fc4ba340496ca0e45d51914f8f1606c60e3c75c6</Sha>
     </Dependency>
     <Dependency Name="Microsoft.DotNet.XUnitExtensions" Version="8.0.0-beta.22554.2">
       <Uri>https://github.com/dotnet/arcade</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index e54249982e315..a7bc4c2a1b545 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -85,7 +85,7 @@
     <MicrosoftDotNetBuildTasksFeedVersion>8.0.0-beta.22554.2</MicrosoftDotNetBuildTasksFeedVersion>
     <MicrosoftDotNetCodeAnalysisVersion>8.0.0-beta.22554.2</MicrosoftDotNetCodeAnalysisVersion>
     <MicrosoftDotNetGenAPIVersion>8.0.0-beta.22554.2</MicrosoftDotNetGenAPIVersion>
-    <MicrosoftDotNetGenFacadesVersion>8.0.0-beta.22554.2</MicrosoftDotNetGenFacadesVersion>
+    <MicrosoftDotNetGenFacadesVersion>8.0.0-beta.22572.2</MicrosoftDotNetGenFacadesVersion>
     <MicrosoftDotNetXUnitExtensionsVersion>8.0.0-beta.22554.2</MicrosoftDotNetXUnitExtensionsVersion>
     <MicrosoftDotNetXUnitConsoleRunnerVersion>2.5.1-beta.22554.2</MicrosoftDotNetXUnitConsoleRunnerVersion>
     <MicrosoftDotNetBuildTasksArchivesVersion>8.0.0-beta.22554.2</MicrosoftDotNetBuildTasksArchivesVersion>
diff --git a/eng/references.targets b/eng/references.targets
index 9ce2c0ed3e60c..0dac678971586 100644
--- a/eng/references.targets
+++ b/eng/references.targets
@@ -59,6 +59,26 @@
     </ItemGroup>
   </Target>
 
+  <!-- Allows building against source assemblies when the 'SkipUseReferenceAssembly' attribute is present on ProjectReference items. -->
+  <Target Name="HandleReferenceAssemblyAttributeForProjectReferences"
+          AfterTargets="ResolveProjectReferences"
+          BeforeTargets="FindReferenceAssembliesForReferences"
+          Condition="'@(ProjectReference)' != '' and '@(_ResolvedProjectReferencePaths)' != ''">
+    <!-- If we have a ProjectReference to CoreLib, we need to compile against implementation assemblies. -->
+    <PropertyGroup Condition="@(_ResolvedProjectReferencePaths->AnyHaveMetadataValue('MSBuildSourceProjectFile', '$(CoreLibProject)'))">
+      <CompileUsingReferenceAssemblies Condition="'$(CompileUsingReferenceAssemblies)' == ''">false</CompileUsingReferenceAssemblies>
+    </PropertyGroup>
+    <!-- Clear the ReferenceAssembly attribute on resolved P2Ps that set SkipUseReferenceAssembly to true. -->
+    <ItemGroup>
+      <_resolvedP2PFiltered Include="@(ProjectReference)"
+                            ProjectReferenceItemSpec="$([System.IO.Path]::GetFullPath('%(ProjectReference.Identity)'))" 
+                            SkipUseReferenceAssembly="%(ProjectReference.SkipUseReferenceAssembly)" />
+      <_ResolvedProjectReferencePaths Condition="'%(_resolvedP2PFiltered.ProjectReferenceItemSpec)' == '%(_resolvedP2PFiltered.MSBuildSourceProjectFile)' and
+                                                 '%(_resolvedP2PFiltered.SkipUseReferenceAssembly)' == 'true'"
+                                      ReferenceAssembly="" />
+    </ItemGroup>
+  </Target>
+
   <ItemDefinitionGroup>
     <TargetPathWithTargetPlatformMoniker>
       <IsReferenceAssemblyProject>$(IsReferenceAssemblyProject)</IsReferenceAssemblyProject>
diff --git a/eng/resolveContract.props b/eng/resolveContract.props
deleted file mode 100644
index fe4224a844a47..0000000000000
--- a/eng/resolveContract.props
+++ /dev/null
@@ -1,14 +0,0 @@
-<Project>
-  <!-- ApiCompat setting -->
-  <PropertyGroup>
-    <ApiCompatValidateAssemblies Condition="'$(IsSourceProject)' == 'true'">true</ApiCompatValidateAssemblies>
-    <!-- Optional rules -->
-    <ApiCompatEnableRuleAttributesMustMatch>true</ApiCompatEnableRuleAttributesMustMatch>
-    <ApiCompatEnableRuleCannotChangeParameterName>true</ApiCompatEnableRuleCannotChangeParameterName>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt" />
-    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)ApiCompatExcludeAttributes.txt" />
-  </ItemGroup>
-</Project>
diff --git a/eng/resolveContract.targets b/eng/resolveContract.targets
index 57bd558774558..c3ed00145d141 100644
--- a/eng/resolveContract.targets
+++ b/eng/resolveContract.targets
@@ -1,20 +1,72 @@
 <Project>
+  <!--
+    ##### Contract project settings #####
+    - Allows referencing contract projects for passing matching reference assemblies to tooling like ApiCompat.
+    - Allows building against contract assemblies when referencing source projects.
+  -->
+
+  <PropertyGroup>
+    <ContractProject Condition="'$(ContractProject)' == ''">$(LibrariesProjectRoot)$(MSBuildProjectName)\ref\$(MSBuildProjectName).csproj</ContractProject>
+    <HasMatchingContract Condition="'$(HasMatchingContract)' == '' and Exists('$(ContractProject)')">true</HasMatchingContract>
+    <!-- Don't build against reference assemblies when projects are packable and the tfm is not the latest .NETCoreApp as
+         such reference assemblies don't ship to customers and only exist for tooling scenarios. -->
+    <AnnotateTargetPathWithContract Condition="'$(AnnotateTargetPathWithContract)' == '' and
+                                               '$(HasMatchingContract)' == 'true' and
+                                               (
+                                                '$(IsPackable)' != 'true' or
+                                                (
+                                                 '$(TargetFrameworkIdentifier)' == '.NETCoreApp' and
+                                                 '$(TargetFrameworkVersion)' == 'v$(NetCoreAppCurrentVersion)'
+                                                )
+                                               )">true</AnnotateTargetPathWithContract>
+  </PropertyGroup>
+
+  <ItemGroup Condition="'$(HasMatchingContract)' == 'true' and '$(ContractProject)' != ''">
+    <ProjectReference Include="$(ContractProject)" ReferenceOutputAssembly="false" OutputItemType="ResolvedMatchingContract" />
+    <!-- We aren't referencing the contract, but make sure it's considered as an input to Compile so that if it changes we rebuild and rerun API compat -->
+    <ProjectReference Include="$(ContractProject)" ReferenceOutputAssembly="false" OutputItemType="CustomAdditionalCompileInputs" />
+  </ItemGroup>
+
+  <!-- Allow P2Ps that target a source project to build against the corresponding ref project. -->
+  <Target Name="AnnotateTargetPathWithTargetPlatformMonikerWithReferenceAssembly"
+          Condition="'$(AnnotateTargetPathWithContract)' == 'true'"
+          DependsOnTargets="ResolveProjectReferences"
+          AfterTargets="GetTargetPathWithTargetPlatformMoniker">
+    <ItemGroup>
+      <TargetPathWithTargetPlatformMoniker ReferenceAssembly="@(ResolvedMatchingContract)" />
+    </ItemGroup>
+  </Target>
+
+  <!-- ##### APICompat settings ##### -->
+
   <PropertyGroup>
     <ApiCompatContractItemName>ResolvedMatchingContract</ApiCompatContractItemName>
     <ApiCompatStrictMode Condition="'$(ApiCompatStrictMode)' == ''">true</ApiCompatStrictMode>
+
+    <!-- Optional rules -->
+    <ApiCompatEnableRuleAttributesMustMatch>true</ApiCompatEnableRuleAttributesMustMatch>
+    <ApiCompatEnableRuleCannotChangeParameterName>true</ApiCompatEnableRuleCannotChangeParameterName>
+
     <_ApiCompatCaptureGroupPattern>.+%5C$([System.IO.Path]::DirectorySeparatorChar)(.+)%5C$([System.IO.Path]::DirectorySeparatorChar)(.+)</_ApiCompatCaptureGroupPattern>
     <_ApiCompatRuntimePrefixPattern>(.+)/(net%5Cd.%5Cd)-(.+)/(.+)</_ApiCompatRuntimePrefixPattern>
     <_ApiCompatLibReplacementString>lib/$1/$2</_ApiCompatLibReplacementString>
     <!-- CoreLib source projects have different output paths. -->
     <_ApiCompatLibReplacementString Condition="'$(MSBuildProjectName)' == 'System.Private.CoreLib'">lib/$(NetCoreAppCurrent)/$2</_ApiCompatLibReplacementString>
+  </PropertyGroup>
 
-    <GenAPIExcludeAttributesList>$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt</GenAPIExcludeAttributesList>
-    <GenAPIHeaderFile>$(RepositoryEngineeringDir)LicenseHeader.txt</GenAPIHeaderFile>
-    <GenAPITargetPath>$([MSBuild]::NormalizePath('$(MSBuildProjectDirectory)', '..', 'ref', '$(AssemblyName).cs'))</GenAPITargetPath>
-    <GenAPILangVersion Condition="'$(LangVersion)' != ''">$(LangVersion)</GenAPILangVersion>
-    <ProjectForGenAPIDocIdGeneration Condition="'$(IsSourceProject)' == 'true' and '$(ProjectForGenAPIDocIdGeneration)' == ''">$(CoreLibProject)</ProjectForGenAPIDocIdGeneration>
+  <PropertyGroup Condition="'$(IsCrossTargetingBuild)' != 'true'">
+    <!-- Disable API compat if the project doesn't have a reference assembly. -->
+    <ApiCompatValidateAssemblies Condition="'$(HasMatchingContract)' != 'true'">false</ApiCompatValidateAssemblies>
+    <!-- TODO: Move into Microsoft.DotNet.GenFacadesNotSupported.targets. -->
+    <!-- Not supported sources are created from the ref assembly, we currently don't produce finalizers in dummy assemblies, so we disable ApiCompat to not fail. -->
+    <ApiCompatValidateAssemblies Condition="'$(GeneratePlatformNotSupportedAssemblyMessage)' != ''">false</ApiCompatValidateAssemblies>
   </PropertyGroup>
 
+  <ItemGroup>
+    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt" />
+    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)ApiCompatExcludeAttributes.txt" />
+  </ItemGroup>
+
   <ItemGroup>
     <!-- Transform the API Compat assemblies passed in to log-able strings. -->
     <ApiCompatLeftAssembliesTransformationPattern Include="$(_ApiCompatCaptureGroupPattern)" ReplacementString="ref/$1/$2" />
@@ -30,64 +82,30 @@
                                          Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', '$(NetCoreAppCurrent)'))" />
   </ItemGroup>
 
-  <PropertyGroup Condition="'$(IsSourceProject)' == 'true'">
-    <ContractProject Condition="'$(ContractProject)' == ''">$(LibrariesProjectRoot)$(MSBuildProjectName)\ref\$(MSBuildProjectName).csproj</ContractProject>
-    <HasMatchingContract Condition="'$(HasMatchingContract)' == '' and Exists('$(ContractProject)')">true</HasMatchingContract>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(IsSourceProject)' == 'true' and '$(IsCrossTargetingBuild)' != 'true'">
-    <!-- Disable API compat if the project doesn't have reference assembly -->
-    <ApiCompatValidateAssemblies Condition="'$(HasMatchingContract)' != 'true'">false</ApiCompatValidateAssemblies>
-    <!-- TODO: Move into Microsoft.DotNet.GenFacadesNotSupported.targets. -->
-    <!-- Not supported sources are created from the ref assembly, we currently don't produce finalizers in dummy assemblies, so we disable ApiCompat to not fail. -->
-    <ApiCompatValidateAssemblies Condition="'$(GeneratePlatformNotSupportedAssemblyMessage)' != ''">false</ApiCompatValidateAssemblies>
-  </PropertyGroup>
-
     <!-- Use the apicompat task package instead of the in-built SDK functionality to consume newer features. -->
   <ItemGroup Condition="'$(EnablePackageValidation)' == 'true' or
                         '$(ApiCompatValidateAssemblies)' == 'true'">
     <PackageReference Include="Microsoft.DotNet.ApiCompat.Task" Version="$(MicrosoftDotNetApiCompatTaskVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(HasMatchingContract)' == 'true' and '$(ContractProject)' != '' and '@(ResolvedMatchingContract)' == ''">
-    <ProjectReference Include="$(ContractProject)" ReferenceOutputAssembly="false" OutputItemType="ResolvedMatchingContract" />
-    <!-- We aren't referencing the contract, but make sure it's considered as an input to Compile so that if it changes we rebuild and rerun API compat -->
-    <ProjectReference Include="$(ContractProject)" ReferenceOutputAssembly="false" OutputItemType="CustomAdditionalCompileInputs" />
-  </ItemGroup>
-  <!-- intentionally empty since we no longer need a target -->
-  <Target Name="ResolveMatchingContract" />
+  <!-- ##### GenAPI settings ##### -->
 
-  <!-- Allow P2Ps that target a source project to build against the corresponding ref project. -->
-  <Target Name="AnnotateTargetPathWithTargetPlatformMonikerWithReferenceAssembly"
-          Condition="'$(HasMatchingContract)' == 'true'"
-          DependsOnTargets="ResolveProjectReferences"
-          AfterTargets="GetTargetPathWithTargetPlatformMoniker">
-    <ItemGroup>
-      <!-- Allow to point to a different reference project than what GenFacades uses to generate the type forwards. -->
-      <TargetPathWithTargetPlatformMoniker ReferenceAssembly="@(ResolvedMatchingContractOverride)" />
-      <TargetPathWithTargetPlatformMoniker ReferenceAssembly="@(ResolvedMatchingContract)"
-                                           Condition="'@(ResolvedMatchingContractOverride)' == ''" />
-    </ItemGroup>
-  </Target>
+  <PropertyGroup>
+    <GenAPIExcludeAttributesList>$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt</GenAPIExcludeAttributesList>
+    <GenAPIHeaderFile>$(RepositoryEngineeringDir)LicenseHeader.txt</GenAPIHeaderFile>
+    <GenAPITargetPath>$([MSBuild]::NormalizePath('$(MSBuildProjectDirectory)', '..', 'ref', '$(AssemblyName).cs'))</GenAPITargetPath>
+    <GenAPILangVersion Condition="'$(LangVersion)' != ''">$(LangVersion)</GenAPILangVersion>
+    <ProjectForGenAPIDocIdGeneration Condition="'$(ProjectForGenAPIDocIdGeneration)' == ''">$(CoreLibProject)</ProjectForGenAPIDocIdGeneration>
+  </PropertyGroup>
 
-  <Target Name="HandleReferenceAssemblyAttributeForProjectReferences"
-          AfterTargets="ResolveProjectReferences"
-          BeforeTargets="FindReferenceAssembliesForReferences"
-          Condition="'@(ProjectReference)' != '' and '@(_ResolvedProjectReferencePaths)' != ''">
-    <!-- If we have a ProjectReference to CoreLib, we need to compile against implementation assemblies. -->
-    <PropertyGroup Condition="@(_ResolvedProjectReferencePaths->AnyHaveMetadataValue('MSBuildSourceProjectFile', '$(CoreLibProject)'))">
-      <CompileUsingReferenceAssemblies Condition="'$(CompileUsingReferenceAssemblies)' == ''">false</CompileUsingReferenceAssemblies>
-    </PropertyGroup>
-    <!-- Clear the ReferenceAssembly attribute on resolved P2Ps that set SkipUseReferenceAssembly to true. -->
-    <ItemGroup>
-      <_resolvedP2PFiltered Include="@(ProjectReference)"
-                            ProjectReferenceItemSpec="$([System.IO.Path]::GetFullPath('%(ProjectReference.Identity)'))" 
-                            SkipUseReferenceAssembly="%(ProjectReference.SkipUseReferenceAssembly)" />
-      <_ResolvedProjectReferencePaths Condition="'%(_resolvedP2PFiltered.ProjectReferenceItemSpec)' == '%(_resolvedP2PFiltered.MSBuildSourceProjectFile)' and
-                                                 '%(_resolvedP2PFiltered.SkipUseReferenceAssembly)' == 'true'"
-                                      ReferenceAssembly="" />
-    </ItemGroup>
-  </Target>
+  <ItemGroup>
+    <!-- GenAPI is currently only invoked on demand and not used as part of the build as it isn't source build compatible. -->
+    <PackageReference Include="Microsoft.DotNet.GenAPI"
+                      Version="$(MicrosoftDotNetGenApiVersion)"
+                      PrivateAssets="all"
+                      IsImplicitlyDefined="true"
+                      Condition="'$(DotNetBuildFromSource)' != 'true'" />
+  </ItemGroup>
 
   <!-- Generate a .txt file with all public types of the project referenced by ProjectForGenAPIDocIdGeneration (e.g. System.Private.CoreLib or System.Private.Uri implementation assembly).
        This file is then later on passed to GenAPI as the list of types which should be "split out" with the conditional compilation logic. -->
diff --git a/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj b/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj
index 153c1f6c56bc6..6394cc80b2673 100644
--- a/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj
+++ b/src/coreclr/System.Private.CoreLib/System.Private.CoreLib.csproj
@@ -348,8 +348,7 @@
 
   <!-- Import refererence assembly and ApiCompat logic -->
   <PropertyGroup>
-    <IsSourceProject>true</IsSourceProject>
+    <ApiCompatValidateAssemblies>true</ApiCompatValidateAssemblies>
   </PropertyGroup>
-  <Import Project="$(RepositoryEngineeringDir)resolveContract.props" />
   <Import Project="$(RepositoryEngineeringDir)resolveContract.targets" />
 </Project>
diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj b/src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj
index b1e8c4cee8e40..0609cc6b648f5 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj
@@ -608,8 +608,7 @@
 
   <!-- Import refererence assembly and ApiCompat logic -->
   <PropertyGroup>
-    <IsSourceProject>true</IsSourceProject>
+    <ApiCompatValidateAssemblies>true</ApiCompatValidateAssemblies>
   </PropertyGroup>
-  <Import Project="$(RepositoryEngineeringDir)resolveContract.props" />
   <Import Project="$(RepositoryEngineeringDir)resolveContract.targets" />
 </Project>
diff --git a/src/libraries/Directory.Build.props b/src/libraries/Directory.Build.props
index 7cf964f8366d8..b46ee2f5249a9 100644
--- a/src/libraries/Directory.Build.props
+++ b/src/libraries/Directory.Build.props
@@ -70,7 +70,6 @@
 
   <Import Project="NetCoreAppLibrary.props" />
   <Import Project="$(RepositoryEngineeringDir)referenceAssemblies.props" Condition="'$(IsReferenceAssemblyProject)' == 'true'" />
-  <Import Project="$(RepositoryEngineeringDir)resolveContract.props" />
 
   <PropertyGroup>
     <!-- Default any assembly not specifying a key to use the Open Key -->
@@ -84,6 +83,7 @@
 
   <!-- Language configuration -->
   <PropertyGroup>
+    <ApiCompatValidateAssemblies Condition="'$(IsSourceProject)' == 'true'">true</ApiCompatValidateAssemblies>
     <GenFacadesIgnoreBuildAndRevisionMismatch>true</GenFacadesIgnoreBuildAndRevisionMismatch>
     <!-- Disable analyzers for tests and unsupported projects -->
     <RunAnalyzers Condition="'$(IsTestProject)' != 'true' and '$(IsSourceProject)' != 'true' and '$(IsGeneratorProject)' != 'true'">false</RunAnalyzers>
diff --git a/src/libraries/Directory.Build.targets b/src/libraries/Directory.Build.targets
index 37fc0f12c2420..28ee4d2f303c6 100644
--- a/src/libraries/Directory.Build.targets
+++ b/src/libraries/Directory.Build.targets
@@ -125,7 +125,7 @@
 
   <Import Project="$(RepositoryEngineeringDir)codeOptimization.targets" />
   <Import Project="$(RepositoryEngineeringDir)references.targets" />
-  <Import Project="$(RepositoryEngineeringDir)resolveContract.targets" />
+  <Import Project="$(RepositoryEngineeringDir)resolveContract.targets" Condition="'$(IsSourceProject)' == 'true'" />
   <Import Project="$(RepositoryEngineeringDir)testing\tests.targets" Condition="'$(EnableTestSupport)' == 'true'" />
   <Import Project="$(RepositoryEngineeringDir)testing\linker\trimmingTests.targets" Condition="'$(IsPublishedAppTestProject)' == 'true'" />
   <Import Project="$(RepositoryEngineeringDir)testing\runtimeConfiguration.targets" />
@@ -141,11 +141,16 @@
     <PackageReference Include="Microsoft.DotNet.Build.Tasks.TargetFramework" Version="$(MicrosoftDotNetBuildTasksTargetFrameworkVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(IsSourceProject)' == 'true' or '$(IsReferenceAssemblyProject)' == 'true' or '$(IsPartialFacadeAssembly)' == 'true'">
-    <PackageReference Include="Microsoft.DotNet.GenAPI" Condition="'$(DotNetBuildFromSource)' != 'true'" Version="$(MicrosoftDotNetGenApiVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
+  <!-- Reference the GenFacades package when the assembly is a partial facade or a PNSE throwing. -->
+  <ItemGroup Condition="'$(IsPartialFacadeAssembly)' == 'true' or
+                        '$(GeneratePlatformNotSupportedAssembly)' == 'true' or
+                        '$(GeneratePlatformNotSupportedAssemblyMessage)' != ''">
     <PackageReference Include="Microsoft.DotNet.GenFacades" Version="$(MicrosoftDotNetGenFacadesVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
   </ItemGroup>
 
+  <!-- GenFacades target that is intentionally empty since we no longer need it. -->
+  <Target Name="ResolveMatchingContract" />
+
   <!--
     Do not clean binplace assets in the ref targeting pack to avoid incremental build failures
     when the SDK tries to resolve the assets from the FrameworkList.
diff --git a/src/libraries/System.DirectoryServices/src/ILLink/ILLink.Suppressions.xml b/src/libraries/System.DirectoryServices/src/ILLink/ILLink.Suppressions.xml
index ca9681a8e8f63..b27ed192851d2 100644
--- a/src/libraries/System.DirectoryServices/src/ILLink/ILLink.Suppressions.xml
+++ b/src/libraries/System.DirectoryServices/src/ILLink/ILLink.Suppressions.xml
@@ -5,7 +5,7 @@
       <argument>ILLink</argument>
       <argument>IL2050</argument>
       <property name="Scope">member</property>
-      <property name="Target">M:System.DirectoryServices.Interop.UnsafeNativeMethods.ADsOpenObject(System.String,System.String,System.String,System.Int32,System.Guid@,System.Object@)</property>
+      <property name="Target">M:System.DirectoryServices.UnsafeNativeMethods.ADsOpenObject(System.String,System.String,System.String,System.Int32,System.Guid@,System.Object@)</property>
     </attribute>
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsOptions.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsOptions.cs
index fe0ad8b59edce..d69988da76d4f 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsOptions.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsOptions.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal enum AdsOptions
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsPropertyOperation.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsPropertyOperation.cs
index 4d5baf7145e79..51e3ca30f7e91 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsPropertyOperation.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsPropertyOperation.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal enum AdsPropertyOperation
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchColumn.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchColumn.cs
index 76dca56431ad3..eec178f3802bb 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchColumn.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchColumn.cs
@@ -3,7 +3,7 @@
 
 using System.Runtime.InteropServices;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     [StructLayout(LayoutKind.Sequential)]
     internal unsafe struct AdsSearchColumn
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferenceInfo.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferenceInfo.cs
index e1b5936c71fd3..0e8c328615446 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferenceInfo.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferenceInfo.cs
@@ -3,7 +3,7 @@
 
 using System.Runtime.InteropServices;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     [StructLayout(LayoutKind.Sequential)]
     internal struct AdsSearchPreferenceInfo
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferences.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferences.cs
index ec409e3a53c30..dd4df804005e0 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferences.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsSearchPreferences.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal enum AdsSearchPreferences
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsSortKey.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsSortKey.cs
index 1c844d7741c97..b25a14b9a29cf 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsSortKey.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsSortKey.cs
@@ -3,7 +3,7 @@
 
 using System.Runtime.InteropServices;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     [StructLayout(LayoutKind.Sequential)]
     internal struct AdsSortKey
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsType.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsType.cs
index 7320c9d512cb4..2c1d54779ab44 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsType.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsType.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal enum AdsType
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsValue2.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsValue2.cs
index 82c2413f1ec71..5aa77b9ea7c95 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsValue2.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsValue2.cs
@@ -3,7 +3,7 @@
 
 using System.Runtime.InteropServices;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     [StructLayout(LayoutKind.Sequential)]
     internal struct Ads_Pointer
diff --git a/src/libraries/System.DirectoryServices/src/Interop/AdsValueHelper2.cs b/src/libraries/System.DirectoryServices/src/Interop/AdsValueHelper2.cs
index 10b208f0784cc..3a19d778c2464 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/AdsValueHelper2.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/AdsValueHelper2.cs
@@ -5,7 +5,7 @@
 using System.Runtime.InteropServices;
 using System.Globalization;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     [StructLayout(LayoutKind.Sequential)]
     internal struct SystemTime
diff --git a/src/libraries/System.DirectoryServices/src/Interop/NativeMethods.cs b/src/libraries/System.DirectoryServices/src/Interop/NativeMethods.cs
index 7ce5748edbc6c..ca45d792515d6 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/NativeMethods.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/NativeMethods.cs
@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal static class NativeMethods
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/SafeNativeMethods.cs b/src/libraries/System.DirectoryServices/src/Interop/SafeNativeMethods.cs
index db401906f69ee..9ae1fdfd26811 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/SafeNativeMethods.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/SafeNativeMethods.cs
@@ -5,7 +5,7 @@
 using System.Security;
 using System.Runtime.InteropServices;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
     internal static partial class SafeNativeMethods
     {
diff --git a/src/libraries/System.DirectoryServices/src/Interop/UnsafeNativeMethods.cs b/src/libraries/System.DirectoryServices/src/Interop/UnsafeNativeMethods.cs
index 30912155a31fc..b6f6e72aad9bd 100644
--- a/src/libraries/System.DirectoryServices/src/Interop/UnsafeNativeMethods.cs
+++ b/src/libraries/System.DirectoryServices/src/Interop/UnsafeNativeMethods.cs
@@ -5,7 +5,7 @@
 using System.Runtime.InteropServices;
 using System.Security;
 
-namespace System.DirectoryServices.Interop
+namespace System.DirectoryServices
 {
 
     [StructLayout(LayoutKind.Explicit)]
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/DomainController.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/DomainController.cs
index 649941c65b93a..59ed8f626e79c 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/DomainController.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/ActiveDirectory/DomainController.cs
@@ -410,7 +410,7 @@ public void SeizeRoleOwnership(ActiveDirectoryRole role)
                 // Increment the RIDAvailablePool by 30k.
                 if (role == ActiveDirectoryRole.RidRole)
                 {
-                    System.DirectoryServices.Interop.UnsafeNativeMethods.IADsLargeInteger ridPool = (System.DirectoryServices.Interop.UnsafeNativeMethods.IADsLargeInteger)roleObjectEntry.Properties[PropertyManager.RIDAvailablePool].Value!;
+                    System.DirectoryServices.UnsafeNativeMethods.IADsLargeInteger ridPool = (System.DirectoryServices.UnsafeNativeMethods.IADsLargeInteger)roleObjectEntry.Properties[PropertyManager.RIDAvailablePool].Value!;
 
                     // check the overflow of the low part
                     if (ridPool.LowPart + UpdateRidPoolSeizureValue < ridPool.LowPart)
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/AuthenticationTypes.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/AuthenticationTypes.cs
index 0a7ece6d9ddb1..f44e180c4c384 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/AuthenticationTypes.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/AuthenticationTypes.cs
@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.DirectoryServices.Interop;
-
 namespace System.DirectoryServices
 {
     /// <devdoc>
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntries.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntries.cs
index 71d53ef690119..cb2082a0f1ffb 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntries.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntries.cs
@@ -3,7 +3,6 @@
 
 using System.Runtime.InteropServices;
 using System.Collections;
-using System.DirectoryServices.Interop;
 
 namespace System.DirectoryServices
 {
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntry.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntry.cs
index 429c4a4f779e8..c4d046cf00656 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntry.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntry.cs
@@ -3,7 +3,6 @@
 
 using System.Runtime.InteropServices;
 using System.Diagnostics;
-using System.DirectoryServices.Interop;
 using System.ComponentModel;
 using System.Threading;
 using System.Reflection;
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntryConfiguration.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntryConfiguration.cs
index df98c45350281..1ff7fcb1e3d2a 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntryConfiguration.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryEntryConfiguration.cs
@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.DirectoryServices.Interop;
 using System.ComponentModel;
 
 namespace System.DirectoryServices
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectorySearcher.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectorySearcher.cs
index 846fffa58e4f2..1ef524342a335 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectorySearcher.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectorySearcher.cs
@@ -4,7 +4,6 @@
 using System.Runtime.InteropServices;
 using System.Collections;
 using System.Collections.Specialized;
-using System.DirectoryServices.Interop;
 using System.ComponentModel;
 
 using INTPTR_INTPTRCAST = System.IntPtr;
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryServicesCOMException.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryServicesCOMException.cs
index ac1ee821b1c46..6ff6d88c56241 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryServicesCOMException.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/DirectoryServicesCOMException.cs
@@ -4,7 +4,6 @@
 using System.ComponentModel;
 using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
-using System.DirectoryServices.Interop;
 
 namespace System.DirectoryServices
 {
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyCollection.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyCollection.cs
index 51878e2cc52d1..38d202f705364 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyCollection.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyCollection.cs
@@ -3,7 +3,6 @@
 
 using System.Runtime.InteropServices;
 using System.Collections;
-using System.DirectoryServices.Interop;
 using System.Globalization;
 
 namespace System.DirectoryServices
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyValueCollection.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyValueCollection.cs
index 4ae15eb0b7a9d..a006b65e7e4bb 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyValueCollection.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/PropertyValueCollection.cs
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections;
-using System.DirectoryServices.Interop;
 
 namespace System.DirectoryServices
 {
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SchemaNameCollection.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SchemaNameCollection.cs
index 853c659ecfd88..7acb9bf62334e 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SchemaNameCollection.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SchemaNameCollection.cs
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections;
-using System.DirectoryServices.Interop;
 
 namespace System.DirectoryServices
 {
diff --git a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SearchResultCollection.cs b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SearchResultCollection.cs
index 4711b60e97b54..dac7ae1f9f754 100644
--- a/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SearchResultCollection.cs
+++ b/src/libraries/System.DirectoryServices/src/System/DirectoryServices/SearchResultCollection.cs
@@ -4,7 +4,6 @@
 using System.Net;
 using System.Runtime.InteropServices;
 using System.Collections;
-using System.DirectoryServices.Interop;
 using System.Text;
 
 using INTPTR_INTPTRCAST = System.IntPtr;
diff --git a/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs b/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
index e0282ac4d556b..57064b5d1b003 100644
--- a/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
+++ b/src/libraries/System.Runtime.Serialization.Schema/src/System/Runtime/Serialization/Schema/CodeExporter.cs
@@ -518,8 +518,8 @@ private static CodeTypeDeclaration CreateTypeDeclaration(string typeName, DataCo
             CodeAttributeDeclaration generatedCodeAttribute = new CodeAttributeDeclaration(typeof(GeneratedCodeAttribute).FullName!);
 
             AssemblyName assemblyName = Assembly.GetExecutingAssembly().GetName();
-            generatedCodeAttribute.Arguments.Add(new CodeAttributeArgument(new CodePrimitiveExpression(assemblyName.Name)));
-            generatedCodeAttribute.Arguments.Add(new CodeAttributeArgument(new CodePrimitiveExpression(assemblyName.Version?.ToString())));
+            generatedCodeAttribute.Arguments.Add(new CodeAttributeArgument(new CodePrimitiveExpression(assemblyName.Name!)));
+            generatedCodeAttribute.Arguments.Add(new CodeAttributeArgument(new CodePrimitiveExpression(assemblyName.Version?.ToString()!)));
 
             // System.Diagnostics.DebuggerStepThroughAttribute not allowed on enums
             // ensure that the attribute is only generated on types that are not enums
@@ -818,7 +818,7 @@ private void ExportClassDataContract(DataContract classDataContract, ContractCod
             {
                 ContractCodeDomInfo baseContractCodeDomInfo = GetContractCodeDomInfo(classDataContract.BaseContract);
                 Debug.Assert(baseContractCodeDomInfo.IsProcessed, "Cannot generate code for type if code for base type has not been generated");
-                type.BaseTypes.Add(baseContractCodeDomInfo.TypeReference);
+                type.BaseTypes.Add(baseContractCodeDomInfo.TypeReference!);
                 AddBaseMemberNames(baseContractCodeDomInfo, contractCodeDomInfo);
                 if (baseContractCodeDomInfo.ReferencedTypeExists)
                 {
@@ -1151,7 +1151,7 @@ private void ExportISerializableDataContract(DataContract classDataContract, Con
             {
                 ContractCodeDomInfo baseContractCodeDomInfo = GetContractCodeDomInfo(classDataContract.BaseContract);
                 GenerateType(classDataContract.BaseContract, baseContractCodeDomInfo);
-                type.BaseTypes.Add(baseContractCodeDomInfo.TypeReference);
+                type.BaseTypes.Add(baseContractCodeDomInfo.TypeReference!);
                 if (baseContractCodeDomInfo.ReferencedTypeExists)
                 {
                     Type? actualType = (Type?)baseContractCodeDomInfo.TypeReference?.UserData[s_codeUserDataActualTypeKey];
@@ -1236,7 +1236,7 @@ private void ExportCollectionDataContract(DataContract collectionContract, Contr
             Debug.Assert(contractCodeDomInfo.TypeDeclaration != null);
 
             CodeTypeDeclaration generatedType = contractCodeDomInfo.TypeDeclaration;
-            generatedType.BaseTypes.Add(baseTypeReference);
+            generatedType.BaseTypes.Add(baseTypeReference!);
             CodeAttributeDeclaration collectionContractAttribute = new CodeAttributeDeclaration(GetClrTypeFullName(typeof(CollectionDataContractAttribute)));
             collectionContractAttribute.Arguments.Add(new CodeAttributeArgument(ImportGlobals.NameProperty, new CodePrimitiveExpression(dataContractName)));
             collectionContractAttribute.Arguments.Add(new CodeAttributeArgument(ImportGlobals.NamespaceProperty, new CodePrimitiveExpression(collectionContract.XmlName.Namespace)));
@@ -1671,7 +1671,7 @@ private static CodeThisReferenceExpression ThisReference
 
         private static CodePrimitiveExpression NullReference
         {
-            get { return new CodePrimitiveExpression(null); }
+            get { return new CodePrimitiveExpression(null!); }
         }
 
         private CodeParameterDeclarationExpression SerializationInfoParameter
@@ -1782,12 +1782,12 @@ private CodeMemberMethod GetSchemaStaticMethod
                         new CodeTypeReferenceExpression(GetCodeTypeReference(typeof(XmlSerializableServices))),
                         nameof(XmlSerializableServices.AddDefaultSchema),
                         new CodeArgumentReferenceExpression(paramDeclaration.Name),
-                        new CodeFieldReferenceExpression(null, TypeNameFieldName)
+                        new CodeFieldReferenceExpression(null!, TypeNameFieldName)
                     )
                 );
                 getSchemaStaticMethod.Statements.Add(
                     new CodeMethodReturnStatement(
-                        new CodeFieldReferenceExpression(null, TypeNameFieldName)
+                        new CodeFieldReferenceExpression(null!, TypeNameFieldName)
                     )
                 );
                 return getSchemaStaticMethod;
diff --git a/src/libraries/apicompat/ApiCompat.proj b/src/libraries/apicompat/ApiCompat.proj
index aae70ebfbb9c9..805a51f2fa39f 100644
--- a/src/libraries/apicompat/ApiCompat.proj
+++ b/src/libraries/apicompat/ApiCompat.proj
@@ -14,7 +14,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <!-- The globally defined DefaultGenApiDocIds.txt and the ApiCompatExcludeAttributes.txt exclude attribute files apply as well. -->
+    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt" />
+    <ApiCompatExcludeAttributesFile Include="$(RepositoryEngineeringDir)ApiCompatExcludeAttributes.txt" />
     <ApiCompatExcludeAttributesFile Include="ApiCompatBaselineExcludedAttributes.txt" />
   </ItemGroup>
 
@@ -53,7 +54,7 @@
       RoslynAssembliesPath="$(RoslynAssembliesPath)"
       GenerateSuppressionFile="$(ApiCompatGenerateSuppressionFile)"
       SuppressionFiles="$(ApiCompatNetCoreAppLatestStableBaselineFile)"
-      EnableRuleAttributesMustMatch="$(ApiCompatEnableRuleAttributesMustMatch)"
+      EnableRuleAttributesMustMatch="true"
       ExcludeAttributesFiles="@(ApiCompatExcludeAttributesFile)"
       LeftAssembliesTransformationPattern="@(ApiCompatNetCoreAppLatestStableLeftAssembliesTransformationPattern)"
       RightAssembliesTransformationPattern="@(ApiCompatNetCoreAppCurrentRightAssembliesTransformationPattern)" />
@@ -65,7 +66,7 @@
       RoslynAssembliesPath="$(RoslynAssembliesPath)"
       GenerateSuppressionFile="$(ApiCompatGenerateSuppressionFile)"
       SuppressionFiles="$(ApiCompatNetStandard21BaselineFile)"
-      EnableRuleAttributesMustMatch="$(ApiCompatEnableRuleAttributesMustMatch)"
+      EnableRuleAttributesMustMatch="true"
       ExcludeAttributesFiles="@(ApiCompatExcludeAttributesFile)"
       LeftAssembliesTransformationPattern="@(ApiCompatNetStandard21LeftAssembliesTransformationPattern)"
       RightAssembliesTransformationPattern="@(ApiCompatNetCoreAppCurrentRightAssembliesTransformationPattern)" />
@@ -77,7 +78,7 @@
       RoslynAssembliesPath="$(RoslynAssembliesPath)"
       GenerateSuppressionFile="$(ApiCompatGenerateSuppressionFile)"
       SuppressionFiles="$(ApiCompatNetStandard20BaselineFile)"
-      EnableRuleAttributesMustMatch="$(ApiCompatEnableRuleAttributesMustMatch)"
+      EnableRuleAttributesMustMatch="true"
       ExcludeAttributesFiles="@(ApiCompatExcludeAttributesFile)"
       LeftAssembliesTransformationPattern="@(ApiCompatNetStandard20LeftAssembliesTransformationPattern)"
       RightAssembliesTransformationPattern="@(ApiCompatNetCoreAppCurrentRightAssembliesTransformationPattern)" />
diff --git a/src/libraries/shims/Directory.Build.targets b/src/libraries/shims/Directory.Build.targets
index 0780fa92ad2e8..c8ee44a679b42 100644
--- a/src/libraries/shims/Directory.Build.targets
+++ b/src/libraries/shims/Directory.Build.targets
@@ -1,17 +1,21 @@
 <Project>
-  <!-- Define before the import so that ResolvedMatchingContract is set before resolveContract.targets is imported. -->
-  <ItemGroup Condition="'$(MSBuildProjectName)' != 'netstandard'">
-    <PackageDownload Include="Microsoft.NETFramework.ReferenceAssemblies.net48"
-                     Version="[$(MicrosoftNETFrameworkReferenceAssembliesLatestPackageVersion)]" />
-    <ResolvedMatchingContract Include="$([MSBuild]::NormalizePath('$(NuGetPackageRoot)', 'microsoft.netframework.referenceassemblies.net48', '$(MicrosoftNETFrameworkReferenceAssembliesLatestPackageVersion)', 'build', '.NETFramework', 'v4.8', '$(MSBuildProjectName).dll'))" />
-  </ItemGroup>
-
   <Import Project="..\Directory.Build.targets" />
 
+  <PropertyGroup>
+  <!-- Tell GenFacades which msbuild item maps to the reference assembly to use. -->
+    <GenFacadesReferenceAssemblyItemName>GenFacadesReferenceAssembly</GenFacadesReferenceAssemblyItemName>
+  </PropertyGroup>
+
   <!-- Tell GenFacades to use reference assemblies instead of the implementation assemblies (for most of the shims). -->
   <PropertyGroup Condition="'$(CompileUsingReferenceAssemblies)' != 'false'">
     <TrimOutPrivateAssembliesFromReferencePath>true</TrimOutPrivateAssembliesFromReferencePath>
     <GeneratePartialFacadeSourceDependsOn>$(GeneratePartialFacadeSourceDependsOn);FindReferenceAssembliesForReferences</GeneratePartialFacadeSourceDependsOn>
     <GenFacadesReferencePathItemName>ReferencePathWithRefAssemblies</GenFacadesReferencePathItemName>
   </PropertyGroup>
+
+  <ItemGroup Condition="'$(MSBuildProjectName)' != 'netstandard'">
+    <PackageDownload Include="Microsoft.NETFramework.ReferenceAssemblies.net48"
+                     Version="[$(MicrosoftNETFrameworkReferenceAssembliesLatestPackageVersion)]" />
+    <GenFacadesReferenceAssembly Include="$([MSBuild]::NormalizePath('$(NuGetPackageRoot)', 'microsoft.netframework.referenceassemblies.net48', '$(MicrosoftNETFrameworkReferenceAssembliesLatestPackageVersion)', 'build', '.NETFramework', 'v4.8', '$(MSBuildProjectName).dll'))" />
+  </ItemGroup>
 </Project>
diff --git a/src/libraries/shims/src/Directory.Build.props b/src/libraries/shims/src/Directory.Build.props
index 5841ecb19f20c..0b532b15f5913 100644
--- a/src/libraries/shims/src/Directory.Build.props
+++ b/src/libraries/shims/src/Directory.Build.props
@@ -5,11 +5,4 @@
     <ContractProject>$(MSBuildThisFileDirectory)..\ref\$(MSBuildProjectName).csproj</ContractProject>
     <IsRuntimeAndReferenceAssembly Condition="!Exists('$(ContractProject)')">true</IsRuntimeAndReferenceAssembly>
   </PropertyGroup>
-
-  <!-- Reference the contract project so that this project's ReferenceAssembly attribute points to the contract, as expected. -->
-  <ItemGroup Condition="'$(IsRuntimeAndReferenceAssembly)' != 'true'">
-    <ProjectReference Include="$(ContractProject)"
-                      ReferenceOutputAssembly="false"
-                      OutputItemType="ResolvedMatchingContractOverride" />
-  </ItemGroup>
 </Project>
diff --git a/src/libraries/shims/src/netstandard.csproj b/src/libraries/shims/src/netstandard.csproj
index cce47288ba655..ee3f1d4f47b01 100644
--- a/src/libraries/shims/src/netstandard.csproj
+++ b/src/libraries/shims/src/netstandard.csproj
@@ -8,6 +8,6 @@
   <ItemGroup>
     <PackageDownload Include="NETStandard.Library.Ref"
                      Version="[$(NETStandardLibraryRefVersion)]" />
-    <ResolvedMatchingContract Include="$(NETStandard21RefPath)$(MSBuildProjectName).dll" />
+    <GenFacadesReferenceAssembly Include="$(NETStandard21RefPath)$(MSBuildProjectName).dll" />
   </ItemGroup>
 </Project>
diff --git a/src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj b/src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj
index 17a336f423c22..b23dce200a1ab 100644
--- a/src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj
+++ b/src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj
@@ -347,9 +347,8 @@
 
   <!-- Import refererence assembly and ApiCompat logic -->
   <PropertyGroup>
-    <IsSourceProject>true</IsSourceProject>
+    <ApiCompatValidateAssemblies>true</ApiCompatValidateAssemblies>
   </PropertyGroup>
-  <Import Project="$(RepositoryEngineeringDir)resolveContract.props" />
   <Import Project="$(RepositoryEngineeringDir)resolveContract.targets" />
 
 </Project>