Fix traversal builds and don't overbuild packages

src/libraries/Microsoft.Extensions.HostFactoryResolver/src/Microsoft.Extensions.HostFactoryResolver.Sources.csproj

@@ -3,8 +3,6 @@
        package infra globs for .cs files. -->
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <!-- The project doesn't compile anything therefore create the package during build. -->
-    <GeneratePackageOnBuild Condition="'$(BuildingAnOfficialBuildLeg)' != 'true'">true</GeneratePackageOnBuild>
     <IsShipping>false</IsShipping>
     <SuppressDependenciesWhenPacking>true</SuppressDependenciesWhenPacking>
     <!-- This is a source package which includes all .cs files by default. -->

src/libraries/Microsoft.NETCore.Platforms/src/Microsoft.NETCore.Platforms.csproj

@@ -6,8 +6,6 @@
     <PackageId>$(MSBuildProjectName)</PackageId>
     <AvoidRestoreCycleOnSelfReference>true</AvoidRestoreCycleOnSelfReference>
     <AssemblyName>Microsoft.NETCore.Platforms.BuildTasks</AssemblyName>
-    <!-- The only output of this project is the package as the tasks aren't packaged. -->
-    <GeneratePackageOnBuild Condition="'$(BuildingAnOfficialBuildLeg)' != 'true'">true</GeneratePackageOnBuild>
 
     <IsSourceProject>false</IsSourceProject>
     <IsPackable>true</IsPackable>

src/libraries/Microsoft.Windows.Compatibility/src/Microsoft.Windows.Compatibility.csproj

@@ -10,20 +10,11 @@
     <PackageDescription>This Windows Compatibility Pack provides access to APIs that were previously available only for .NET Framework. It can be used from both .NET Core as well as .NET Standard.</PackageDescription>
   </PropertyGroup>
 
-  <!-- By default, don't build the project references to avoid unnecessary incremental builds. -->
-  <ItemDefinitionGroup Condition="'$(BuildProjectReferences)' != 'true'">
-    <ProjectReference>
-      <BuildReference>false</BuildReference>
-    </ProjectReference>
-  </ItemDefinitionGroup>
-
   <ItemGroup>
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Win32.Registry.AccessControl\src\Microsoft.Win32.Registry.AccessControl.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Win32.SystemEvents\src\Microsoft.Win32.SystemEvents.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)System.CodeDom\src\System.CodeDom.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)System.ComponentModel.Composition\src\System.ComponentModel.Composition.csproj" />
-    <ProjectReference Include="$(LibrariesProjectRoot)System.ComponentModel.Composition.Registration\src\System.ComponentModel.Composition.Registration.csproj"
-                      Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'netstandard2.1'))" />
     <ProjectReference Include="$(LibrariesProjectRoot)System.Configuration.ConfigurationManager\src\System.Configuration.ConfigurationManager.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)System.Data.Odbc\src\System.Data.Odbc.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)System.Data.OleDb\src\System.Data.OleDb.csproj" />
@@ -49,6 +40,10 @@
     <ProjectReference Include="$(LibrariesProjectRoot)System.Threading.AccessControl\src\System.Threading.AccessControl.csproj" />
   </ItemGroup>
 
+  <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'netstandard2.1'))">
+    <ProjectReference Include="$(LibrariesProjectRoot)System.ComponentModel.Composition.Registration\src\System.ComponentModel.Composition.Registration.csproj" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="System.Data.SqlClient" Version="$(SystemDataSqlClientVersion)" />  
     <PackageReference Include="System.ServiceModel.Primitives;

src/libraries/libraries-packages.proj

@@ -2,13 +2,16 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.DotNet.Build.Tasks.Packaging" Version="$(MicrosoftDotNetBuildTasksPackagingVersion)" />
+  </ItemGroup>
 
-    <ProjectReference Include="$(MSBuildThisFileDirectory)System.Runtime.Experimental\ref\System.Runtime.Experimental.csproj"
-                      Condition="'$(BuildAllConfigurations)' == 'true'" />
+  <ItemGroup Condition="'$(BuildAllConfigurations)' == 'true'">
+    <ProjectReference Include="$(MSBuildThisFileDirectory)System.Runtime.Experimental\ref\System.Runtime.Experimental.csproj" />
     <ProjectReference Include="$(PkgDir)*\*.proj" Exclude="$(PkgDir)test\*" />
     <ProjectReference Include="$(MSBuildThisFileDirectory)*\src\*.*proj"
-                      Condition="'$(BuildAllConfigurations)' == 'true'"
-                      Exclude="$(MSBuildThisFileDirectory)*\src\**\*.shproj"/>
+                      Exclude="$(MSBuildThisFileDirectory)*\src\**\*.shproj" />
+    <!-- Don't build *projs again during the Pack task that have already been built. -->
+    <ProjectReference Update="@(ProjectReference)"
+                      AdditionalProperties="NoBuild=true" />
   </ItemGroup>
 
   <!-- Need the PackageIndexFile file property from baseline.props -->

src/libraries/pkg/runtime.native.System.IO.Ports/runtime.native.System.IO.Ports.proj

@@ -1,7 +1,7 @@
 <Project DefaultTargets="Build">
   <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props))" />
 
-  <ItemGroup Condition="'$(BuildAllConfigurations)' == 'true'">
+  <ItemGroup>
     <!-- identity project built in AllConfigurations leg, runtime specific projects are included through netcoreapp.rids.props -->
     <Project Include="$(MSBuildProjectName).pkgproj" />
   </ItemGroup>

src/libraries/src.proj

@@ -7,6 +7,12 @@
   <ItemGroup>
     <_allSrc Include="$(MSBuildThisFileDirectory)*\src\*.csproj"
              Exclude="@(ProjectExclusions)" />
+    <!-- Don't build ProjectReferences of the compat pack in a traversal build to avoid unnecessary incremental builds. -->
+    <_allSrc Update="$(MSBuildThisFileDirectory)Microsoft.Windows.Compatibility\src\Microsoft.Windows.Compatibility.csproj"
+             AdditionalProperties="BuildProjectReferences=false" />
+    <!-- Only build the compat pack in the allconfigurations leg. -->
+    <_allSrc Remove="$(MSBuildThisFileDirectory)Microsoft.Windows.Compatibility\src\Microsoft.Windows.Compatibility.csproj"
+             Condition="'$(BuildAllConfigurations)' != 'true'" />
     <NonNetCoreAppProject Include="@(_allSrc)"
                           Exclude="@(NetCoreAppLibrary->'%(Identity)\src\%(Identity).csproj')" />
     <NetCoreAppProject Include="$(CoreLibProject);