Avoid duplicate 'WindowsAppRuntimeAutoInitializer.cpp' compilation

Author: mschofie

build/NuSpecs/WindowsAppSDK-Nuget-Native.AutoInitializer.targets

@@ -3,13 +3,27 @@
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
   <Target Name="WindowsAppRuntimeAutoInitializer">
+    <PropertyGroup>
+      <WindowsAppRuntimeAutoInitializerPath>$(MSBuildThisFileDirectory)..\..\include\WindowsAppRuntimeAutoInitializer.cpp</WindowsAppRuntimeAutoInitializerPath>
+      <WindowsAppRuntimeAutoInitializerDefines />
+      <WindowsAppRuntimeAutoInitializerDefines Condition="'$(WindowsAppSdkBootstrapInitialize)'=='true'">$(WindowsAppRuntimeAutoInitializerDefines);MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_BOOTSTRAP</WindowsAppRuntimeAutoInitializerDefines>
+      <WindowsAppRuntimeAutoInitializerDefines Condition="'$(WindowsAppSdkDeploymentManagerInitialize)'=='true'">$(WindowsAppRuntimeAutoInitializerDefines);MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_DEPLOYMENTMANAGER</WindowsAppRuntimeAutoInitializerDefines>
+      <WindowsAppRuntimeAutoInitializerDefines Condition="'$(WindowsAppSdkUndockedRegFreeWinRTInitialize)'=='true'">$(WindowsAppRuntimeAutoInitializerDefines);MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_UNDOCKEDREGFREEWINRT</WindowsAppRuntimeAutoInitializerDefines>
+      <WindowsAppRuntimeAutoInitializerDefines Condition="'$(WindowsAppSdkCompatibilityInitialize)'=='true'">$(WindowsAppRuntimeAutoInitializerDefines);MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_COMPATIBILITY</WindowsAppRuntimeAutoInitializerDefines>
+    </PropertyGroup>
+
+    <!--
+    Add a ClCompile for the 'WindowsAppRuntimeAutoInitializer'. This is done in two steps;
+      1. Add the ClCompile item with no metadata, so the default metadata is applied.
+      2. Add a second ClCompile item that uses the %(Identity) metadata to force a 'task batch' with just the one item
+          we want to modify. This allows us to use "%(PreprocessorDefinitions)" (without causing more task batching) to
+          append the PreprocessorDefinitions to apply.
+    -->
     <ItemGroup>
-      <ClCompile Include="$(MSBuildThisFileDirectory)..\..\include\WindowsAppRuntimeAutoInitializer.cpp">
+      <ClCompile Include="$(WindowsAppRuntimeAutoInitializerPath)" />
+      <ClCompile Condition=" '%(Identity)' == '$(WindowsAppRuntimeAutoInitializerPath)' ">
         <PrecompiledHeader>NotUsing</PrecompiledHeader>
-        <PreprocessorDefinitions Condition="'$(WindowsAppSdkBootstrapInitialize)'=='true'">MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_BOOTSTRAP;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-        <PreprocessorDefinitions Condition="'$(WindowsAppSdkDeploymentManagerInitialize)'=='true'">MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_DEPLOYMENTMANAGER;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-        <PreprocessorDefinitions Condition="'$(WindowsAppSdkUndockedRegFreeWinRTInitialize)'=='true'">MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_UNDOCKEDREGFREEWINRT;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-        <PreprocessorDefinitions Condition="'$(WindowsAppSdkCompatibilityInitialize)'=='true'">MICROSOFT_WINDOWSAPPSDK_AUTOINITIALIZE_COMPATIBILITY;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+        <PreprocessorDefinitions>$(WindowsAppRuntimeAutoInitializerDefines);%(PreprocessorDefinitions)</PreprocessorDefinitions>
       </ClCompile>
     </ItemGroup>
   </Target>