From 64765748106661eb621a666f168eec9ba47f8dd9 Mon Sep 17 00:00:00 2001
From: Nick Guerrera <nicholg@microsoft.com>
Date: Tue, 13 Sep 2016 16:45:04 -0700
Subject: [PATCH 1/2] Port traversal targets for cross-targeting to xplat
 branch

Cherry pick 0a6e5f11fe3de4c5c9bf377b29b311507775e255

Conflicts:
 src/XMakeTasks/Microsoft.Build.Tasks.csproj
---
 setup/files.swr                               |   2 +
 src/XMakeTasks/Microsoft.Build.Tasks.csproj   |   7 ++
 src/XMakeTasks/Microsoft.CSharp.targets       |  14 +++
 .../Microsoft.Common.CrossTargeting.targets   |  16 +++
 .../Microsoft.Common.CurrentVersion.targets   | 110 +++++++++++++++---
 src/XMakeTasks/Microsoft.VisualBasic.targets  |  14 +++
 6 files changed, 146 insertions(+), 17 deletions(-)
 create mode 100644 src/XMakeTasks/Microsoft.Common.CrossTargeting.targets

diff --git a/setup/files.swr b/setup/files.swr
index 6af9c760208..f99d202839d 100644
--- a/setup/files.swr
+++ b/setup/files.swr
@@ -17,6 +17,7 @@ folder InstallDir:\MSBuild\15.0\Bin
   file source=$(X86BinPath)System.Threading.Tasks.Dataflow.dll vs.file.ngen=yes
   file source=$(X86BinPath)System.Collections.Immutable.dll vs.file.ngen=yes
   file source=$(X86BinPath)Microsoft.Common.CurrentVersion.targets
+  file source=$(X86BinPath)Microsoft.Common.CrossTargeting.targets
   file source=$(X86BinPath)Microsoft.Common.overridetasks
   file source=$(X86BinPath)Microsoft.Common.targets
   file source=$(X86BinPath)Microsoft.Common.tasks
@@ -135,6 +136,7 @@ folder InstallDir:\MSBuild\15.0\Bin\amd64
   file source=$(X86BinPath)System.Threading.Tasks.Dataflow.dll vs.file.ngen=yes
   file source=$(X86BinPath)System.Collections.Immutable.dll vs.file.ngen=yes
   file source=$(X86BinPath)Microsoft.Common.CurrentVersion.targets
+  file source=$(X86BinPath)Microsoft.Common.CrossTargeting.targets
   file source=$(X86BinPath)Microsoft.Common.overridetasks
   file source=$(X86BinPath)Microsoft.Common.targets
   file source=$(X86BinPath)Microsoft.Common.tasks
diff --git a/src/XMakeTasks/Microsoft.Build.Tasks.csproj b/src/XMakeTasks/Microsoft.Build.Tasks.csproj
index 94c6b30f34b..f7985dc33b0 100644
--- a/src/XMakeTasks/Microsoft.Build.Tasks.csproj
+++ b/src/XMakeTasks/Microsoft.Build.Tasks.csproj
@@ -721,6 +721,10 @@
     <Content Include="Microsoft.Common.CurrentVersion.targets">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Microsoft.Common.CrossTargeting.targets">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <SubType>Designer</SubType>
+    </Content>
     <Content Include="Microsoft.Common.targets">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
@@ -821,6 +825,9 @@
     <DataFile Include="Microsoft.Common.CurrentVersion.targets">
       <SubType>Designer</SubType>
     </DataFile>
+    <DataFile Include="Microsoft.Common.CrossTargeting.targets">
+      <SubType>Designer</SubType>
+    </DataFile>
     <DataFile Include="Microsoft.NETFramework.targets" />
     <DataFile Include="Microsoft.NETFramework.CurrentVersion.targets" />
     <DataFile Include="Microsoft.NETFramework.props">
diff --git a/src/XMakeTasks/Microsoft.CSharp.targets b/src/XMakeTasks/Microsoft.CSharp.targets
index 74fe11deedf..c824b0c487b 100644
--- a/src/XMakeTasks/Microsoft.CSharp.targets
+++ b/src/XMakeTasks/Microsoft.CSharp.targets
@@ -17,6 +17,15 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <!-- 
+        We are doing a cross-targeting build if there is no list of target frameworks specified
+        nor is there a current target framework being built individually. In that case, this import is
+        redirected to Microsoft.Common.CrossTargeting.targets.
+   -->
+   <PropertyGroup Condition="'$(TargetFrameworks)' != '' and '$(TargetFramework)' == ''">
+      <IsCrossTargetingBuild>true</IsCrossTargetingBuild>
+   </PropertyGroup>
+
+   <!--
         In VS 2010 SP1 and VS 2012, both supported for asset compatibility, the MSBuild installed 
         as part of them did not enforce using the local ToolsVersion (4.0) in all cases, but instead 
         just used whatever ToolsVersion was in the project file if it existed on the machine, and 
@@ -40,6 +49,11 @@ Copyright (C) Microsoft Corporation. All rights reserved.
             <CscToolPath Condition="'$(CscToolPath)' == '' and '$(BuildingInsideVisualStudio)' != 'true'">$(MsBuildFrameworkToolsPath)</CscToolPath>
          </PropertyGroup>
       </When>
+      <When Condition="'$(IsCrossTargetingBuild)' == 'true'">
+         <PropertyGroup>
+            <CSharpTargetsPath>$(MSBuildToolsPath)\Microsoft.Common.CrossTargeting.targets</CSharpTargetsPath>
+          </PropertyGroup>
+      </When>
       <Otherwise>
          <PropertyGroup>
             <CSharpTargetsPath>$(MSBuildToolsPath)\Microsoft.CSharp.CurrentVersion.targets</CSharpTargetsPath>
diff --git a/src/XMakeTasks/Microsoft.Common.CrossTargeting.targets b/src/XMakeTasks/Microsoft.Common.CrossTargeting.targets
new file mode 100644
index 00000000000..8f7860fcc85
--- /dev/null
+++ b/src/XMakeTasks/Microsoft.Common.CrossTargeting.targets
@@ -0,0 +1,16 @@
+<!--
+***********************************************************************************************
+Microsoft.Common.CrossTargeting.targets
+
+WARNING:  DO NOT MODIFY this file unless you are knowledgeable about MSBuild and have
+          created a backup copy.  Incorrect changes to this file will make it
+          impossible to load or build your projects from the command-line or the IDE.
+
+Copyright (C) Microsoft Corporation. All rights reserved.
+***********************************************************************************************
+-->
+
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$(CoreCrossTargetingTargetsPath)" 
+          Condition="'$(CoreCrossTargetingTargetsPath)' != '' and Exists('$(CoreCrossTargetingTargetsPath)')" />
+</Project>
diff --git a/src/XMakeTasks/Microsoft.Common.CurrentVersion.targets b/src/XMakeTasks/Microsoft.Common.CurrentVersion.targets
index 33fa35a9f7d..94b6a0a1486 100644
--- a/src/XMakeTasks/Microsoft.Common.CurrentVersion.targets
+++ b/src/XMakeTasks/Microsoft.Common.CurrentVersion.targets
@@ -884,12 +884,12 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   <Target Name="BuildGenerateSources" DependsOnTargets="BuildGenerateSourcesTraverse;$(BuildGenerateSourcesAction)" />
 
-  <Target Name="BuildGenerateSourcesTraverse" DependsOnTargets="AssignProjectConfiguration;_SplitProjectReferencesByFileExistence">
+  <Target Name="BuildGenerateSourcesTraverse" DependsOnTargets="PrepareProjectReferences">
     <MSBuild
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="BuildGenerateSources"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework);"
         Condition="'$(BuildPassReferences)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and '@(_MSBuildProjectReferenceExistent)' != '' and '%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true'"
         ContinueOnError="!$(BuildingProject)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -909,12 +909,12 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   <Target Name="BuildCompile" DependsOnTargets="BuildCompileTraverse;$(BuildCompileAction)" />
 
-  <Target Name="BuildCompileTraverse" DependsOnTargets="AssignProjectConfiguration;_SplitProjectReferencesByFileExistence">
+  <Target Name="BuildCompileTraverse" DependsOnTargets="PrepareProjectReferences">
     <MSBuild
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="BuildCompile"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'$(BuildPassReferences)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and '@(_MSBuildProjectReferenceExistent)' != ''  and '%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true'"
         ContinueOnError="!$(BuildingProject)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -934,12 +934,12 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   <Target Name="BuildLink" DependsOnTargets="BuildLinkTraverse;$(BuildLinkAction)" />
 
-  <Target Name="BuildLinkTraverse" DependsOnTargets="AssignProjectConfiguration;_SplitProjectReferencesByFileExistence" >
+  <Target Name="BuildLinkTraverse" DependsOnTargets="PrepareProjectReferences" >
     <MSBuild
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="BuildLink"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'$(BuildPassReferences)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and '@(_MSBuildProjectReferenceExistent)' != ''  and '%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true'"
         ContinueOnError="!$(BuildingProject)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -1487,6 +1487,81 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   </Target>
 
+  <!--
+    ====================================================================================
+                                        _GetProjectReferenceTargetFrameworkProperties
+
+    Builds the GetTargetFrameworkProperties target of all existent project references,
+    passing $(TargetFrameworkMoniker) as $(ReferringTargetFramework) and sets the
+    SetTargetFramework metadata of the project reference to the value that is returned.
+
+    This allows a cross-targeting project to select how it should be configured to
+    build against the most appropriate target for the referring target framework.
+
+    ======================================================================================
+  -->
+  <Target Name="_GetProjectReferenceTargetFrameworkProperties" Outputs="%(_MSBuildProjectReferenceExistent.Identity)">
+    <MSBuild
+        Projects="%(_MSBuildProjectReferenceExistent.Identity)"
+        Targets="GetTargetFrameworkProperties"
+        BuildInParallel="$(BuildInParallel)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); ReferringTargetFramework=$(TargetFrameworkMoniker)"
+        ContinueOnError="!$(BuildingProject)"
+        RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
+
+      <Output TaskParameter="TargetOutputs" PropertyName="_ProjectReferenceTargetFrameworkProperties" />
+    </MSBuild>
+
+    <ItemGroup>
+      <_MSBuildProjectReferenceExistent Condition="'%(_MSBuildProjectReferenceExistent.Identity)' == '%(Identity)'">
+        <SetTargetFramework>$(_ProjectReferenceTargetFrameworkProperties)</SetTargetFramework>
+      </_MSBuildProjectReferenceExistent>
+    </ItemGroup>
+
+    <PropertyGroup>
+      <_ProjectReferenceTargetFrameworkProperties />
+    </PropertyGroup>
+  </Target>
+
+  <!--
+    ============================================================
+                                    GetTargetFrameworkProperties
+
+    Overrridden by cross-targeting projects to return the set of
+    properties (in the form "key1=value1;...keyN=valueN") needed
+    to build it with the best target for the referring project's
+    target framework.
+
+    The referring project's $(TargetFrameworkMoniker) is passed 
+    in as $(ReferringTargetFramework)
+  -->
+  <Target Name="GetTargetFrameworkProperties" />
+
+  <!--
+    ============================================================
+                                        PrepareProjectReferences
+
+    Prepares project references for consumption by other targets.
+
+        [IN]
+        @(ProjectReference) - The list of project references.
+
+        [OUT]
+        @(ProjectReferenceWithConfiguration)   - Project references with apporpriate metadata
+        @(_MSBuildProjectReferenceExistent)    - Subset of @(ProjectReferenceWithConfiguration) that exist 
+                                                 with added SetTargetFramework metadata for cross-targeting
+        @(_MSBuildProjectReferenceNonExistent) - Subset of  @(ProjectReferenceWithConfiguration) that do not exist
+    ============================================================
+  -->
+  <PropertyGroup>
+    <PrepareProjectReferencesDependsOn>
+      AssignProjectConfiguration;
+      _SplitProjectReferencesByFileExistence;
+      _GetProjectReferenceTargetFrameworkProperties
+    </PrepareProjectReferencesDependsOn>
+  </PropertyGroup>
+  <Target Name="PrepareProjectReferences" DependsOnTargets="$(PrepareProjectReferencesDependsOn)" />
+
   <!--
     ============================================================
                                         ResolveProjectReferences
@@ -1514,7 +1589,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
   <Target
       Name="ResolveProjectReferences"
-      DependsOnTargets="AssignProjectConfiguration;_SplitProjectReferencesByFileExistence"
+      DependsOnTargets="PrepareProjectReferences"
       Returns="@(_ResolvedNativeProjectReferencePaths);@(_ResolvedProjectReferencePaths)">
 
     <!--
@@ -1529,7 +1604,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="GetTargetPath"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and ('$(BuildingInsideVisualStudio)' == 'true' or '$(BuildProjectReferences)' != 'true') and '$(VisualStudioVersion)' != '10.0' and '@(_MSBuildProjectReferenceExistent)' != ''"
         ContinueOnError="!$(BuildingProject)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -1556,7 +1631,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="%(_MSBuildProjectReferenceExistent.Targets);GetTargetPath"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and ('$(BuildingInsideVisualStudio)' == 'true' or '$(BuildProjectReferences)' != 'true') and '$(VisualStudioVersion)' == '10.0' and '@(_MSBuildProjectReferenceExistent)' != ''"
         ContinueOnError="!$(BuildingProject)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -1573,7 +1648,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="%(_MSBuildProjectReferenceExistent.Targets)"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform);  %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and '$(BuildingInsideVisualStudio)' != 'true' and '$(BuildProjectReferences)' == 'true' and '@(_MSBuildProjectReferenceExistent)' != ''"
         ContinueOnError="$(ContinueOnError)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -1590,7 +1665,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="GetNativeManifest"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'%(_MSBuildProjectReferenceExistent.BuildReference)' == 'true' and '@(ProjectReferenceWithConfiguration)' != '' and '$(BuildingProject)' == 'true' and '@(_MSBuildProjectReferenceExistent)' != ''"
         ContinueOnError="$(ContinueOnError)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -2115,10 +2190,10 @@ Copyright (C) Microsoft Corporation. All rights reserved.
      </ItemGroup>
    </Target>
 
-  <Target Name="GetReferenceTargetPlatformMonikers" DependsOnTargets="AssignProjectConfiguration;_SplitProjectReferencesByFileExistence">
+  <Target Name="GetReferenceTargetPlatformMonikers" DependsOnTargets="PrepareProjectReferences">
     <MSBuild
       Projects="@(_MSBuildProjectReferenceExistent)"
-      Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+      Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
       Targets="GetTargetPathWithTargetPlatformMoniker"
       BuildInParallel="$(BuildInParallel)"
       ContinueOnError="!$(BuildingProject)"
@@ -4010,7 +4085,8 @@ Copyright (C) Microsoft Corporation. All rights reserved.
   <PropertyGroup>
     <GetCopyToOutputDirectoryItemsDependsOn>
       AssignTargetPaths;
-      _SplitProjectReferencesByFileExistence
+      _SplitProjectReferencesByFileExistence;
+      _GetProjectReferenceTargetFrameworkProperties
     </GetCopyToOutputDirectoryItemsDependsOn>
   </PropertyGroup>
   <Target
@@ -4034,7 +4110,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="GetCopyToOutputDirectoryItems"
         BuildInParallel="$(BuildInParallel)"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         Condition="'@(_MSBuildProjectReferenceExistent)' != '' and '$(_GetChildProjectCopyToOutputDirectoryItems)' == 'true' and '%(_MSBuildProjectReferenceExistent.Private)' != 'false' and '$(UseCommonOutputDirectory)' != 'true'"
         ContinueOnError="$(ContinueOnError)"
         RemoveProperties="%(_MSBuildProjectReferenceExistent.GlobalPropertiesToRemove)">
@@ -4552,7 +4628,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
     -->
   <Target
       Name="CleanReferencedProjects"
-      DependsOnTargets="AssignProjectConfiguration; _SplitProjectReferencesByFileExistence">
+      DependsOnTargets="PrepareProjectReferences">
 
     <!--
         When building the project directly from the command-line, clean those referenced projects
@@ -4562,7 +4638,7 @@ Copyright (C) Microsoft Corporation. All rights reserved.
     <MSBuild
         Projects="@(_MSBuildProjectReferenceExistent)"
         Targets="Clean"
-        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform)"
+        Properties="%(_MSBuildProjectReferenceExistent.SetConfiguration); %(_MSBuildProjectReferenceExistent.SetPlatform); %(_MSBuildProjectReferenceExistent.SetTargetFramework)"
         BuildInParallel="$(BuildInParallel)"
         Condition="'$(BuildingInsideVisualStudio)' != 'true' and '$(BuildProjectReferences)' == 'true' and '@(_MSBuildProjectReferenceExistent)' != ''"
         ContinueOnError="$(ContinueOnError)"
diff --git a/src/XMakeTasks/Microsoft.VisualBasic.targets b/src/XMakeTasks/Microsoft.VisualBasic.targets
index 91cd882c93d..71193b344c9 100644
--- a/src/XMakeTasks/Microsoft.VisualBasic.targets
+++ b/src/XMakeTasks/Microsoft.VisualBasic.targets
@@ -18,6 +18,15 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <!-- 
+       We are doing a cross-targeting build if there is no list of target frameworks specified
+       nor is there a current target framework being built individually. In that case, this import is
+       redirected to Microsoft.Common.CrossTargeting.targets.
+   -->
+   <PropertyGroup Condition="'$(TargetFrameworks)' != '' and '$(TargetFramework)' == ''">
+      <IsCrossTargetingBuild>true</IsCrossTargetingBuild>
+   </PropertyGroup>
+
+   <!--
         In VS 2010 SP1 and VS 2012, both supported for asset compatibility, the MSBuild installed 
         as part of them did not enforce using the local ToolsVersion (4.0) in all cases, but instead 
         just used whatever ToolsVersion was in the project file if it existed on the machine, and 
@@ -41,6 +50,11 @@ Copyright (C) Microsoft Corporation. All rights reserved.
         <VbcToolPath Condition="'$(VbcToolPath)' == '' and '$(BuildingInsideVisualStudio)' != 'true'">$(MsBuildFrameworkToolsPath)</VbcToolPath>
       </PropertyGroup>
     </When>
+    <When Condition="'$(IsCrossTargetingBuild)' == 'true'">
+      <PropertyGroup>
+        <VisualBasicTargetsPath>$(MSBuildToolsPath)\Microsoft.Common.CrossTargeting.targets</VisualBasicTargetsPath>
+      </PropertyGroup>
+    </When>
     <Otherwise>
       <PropertyGroup>
         <VisualBasicTargetsPath>$(MSBuildToolsPath)\Microsoft.VisualBasic.CurrentVersion.targets</VisualBasicTargetsPath>

From e12c48fbd8de822edcc75e6967b339f43bec55b2 Mon Sep 17 00:00:00 2001
From: Nick Guerrera <nicholg@microsoft.com>
Date: Wed, 14 Sep 2016 12:56:50 -0700
Subject: [PATCH 2/2] Add cross-targeting targets to nuspec

---
 src/nuget/Microsoft.Build.Targets.nuspec | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/nuget/Microsoft.Build.Targets.nuspec b/src/nuget/Microsoft.Build.Targets.nuspec
index bfe799a2f01..493cbf0ce80 100644
--- a/src/nuget/Microsoft.Build.Targets.nuspec
+++ b/src/nuget/Microsoft.Build.Targets.nuspec
@@ -30,6 +30,7 @@
   </metadata>
   <files>
     <file src="_._" target="lib\netstandard1.3" />
+    <file src="Microsoft.Common.CrossTargeting.targets" target="runtimes\any\native" />
     <file src="Microsoft.Common.CurrentVersion.targets" target="runtimes\any\native" />
     <file src="Microsoft.Common.targets" target="runtimes\any\native" />
     <file src="Microsoft.CSharp.CurrentVersion.targets" target="runtimes\any\native" />