Use custom property instead of TargetPlatformIdentifier to avoid SDK conflicts

Author: Arlodotexe

MultiTarget/MultiTargetIdentifiers.props

@@ -43,8 +43,11 @@
 
     <IsUwp Condition="'$(IsUwp)' == '' AND $(UwpTargetFramework.Contains('$(TargetFramework);')) AND '$(UwpTargetFramework)' != '' AND '$(MultiTargetsUwp)' == 'true'">true</IsUwp>
     <IsWinAppSdk Condition="'$(IsWinAppSdk)' == '' AND $(WinAppSdkTargetFramework.Contains('$(TargetFramework);')) AND '$(WinAppSdkTargetFramework)' != '' AND '$(MultiTargetsWasdk)' == 'true'">true</IsWinAppSdk>
-    <TargetPlatformIdentifier>$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</TargetPlatformIdentifier>
-    <IsWindowsTfm Condition="$(TargetPlatformIdentifier) == 'windows'">true</IsWindowsTfm>
+    
+    <MultiTargetPlatformIdentifier Condition="'$(MultiTargetPlatformIdentifier)' == ''">$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</MultiTargetPlatformIdentifier>
+
+    <!-- TODO: Investigate. Should be named IsWindows, but ran into unexpected issues in VS. Property name may be taken and internally used by an SDK. -->
+    <IsWindowsTfm Condition="$(MultiTargetPlatformIdentifier) == 'windows'">true</IsWindowsTfm>
 
     <IsDroid Condition="'$(IsDroid)' == '' AND $(AndroidLibTargetFramework.Contains('$(TargetFramework);')) AND '$(AndroidLibTargetFramework)' != '' AND '$(MultiTargetsDroid)' == 'true'">true</IsDroid>
     <IsMacOS Condition="'$(IsMacOS)' == '' AND $(MacOSLibTargetFramework.Contains('$(TargetFramework);')) AND '$(MacOSLibTargetFramework)' != '' AND '$(MultiTargetsMacOS)' == 'true'">true</IsMacOS>
@@ -62,6 +65,6 @@
     <WinUIMajorVersion Condition="'$(HasWinUI)' == 'true' AND '$(IsUwp)' == 'true' AND $(WinUIMajorVersion) == ''">2</WinUIMajorVersion>
     <WinUIMajorVersion Condition="'$(HasWinUI)' == 'true' AND '$(IsWinAppSdk)' == 'true' AND $(WinUIMajorVersion) == ''">3</WinUIMajorVersion>
 
-    <UseUwp Condition="'$(HasWinUI)' == 'true' AND '$(IsUwp)' == 'true' AND '$(IsWindowsTfm)' == 'true'">true</UseUwp>
+    <UseUwp Condition="'$(HasWinUI)' == 'true' AND '$(IsUwp)' == 'true' AND '$(MultiTargetPlatformIdentifier)' == 'windows'">true</UseUwp>
   </PropertyGroup>
 </Project>

MultiTarget/NoWarn.props

@@ -1,6 +1,6 @@
 <Project>  
   <!-- Disable warnings for 'This call site is reachable on all platforms.' caused by underlying platform. -->
-  <PropertyGroup Condition="'$(IsUwp)' == 'true' AND '$(IsWindowsTfm)' == 'true'">
+  <PropertyGroup Condition="'$(IsUwp)' == 'true' AND '$(MultiTargetPlatformIdentifier)' == 'windows'">
     <NoWarn>$(NoWarn);CA1416;NETSDK1219;</NoWarn>
   </PropertyGroup>
 

MultiTarget/PackageReferences/Uwp.props

@@ -1,9 +1,9 @@
 <Project>
   <ItemGroup>
     <PackageReference Condition="'$(HasWinUI)' == 'true'" Include="Microsoft.UI.Xaml" Version="2.8.7-prerelease.241119001" />
-    <PackageReference Condition="'$(IsWindowsTfm)' == 'true'" Include="Microsoft.Windows.CsWinRT" Version="2.1.6" PrivateAssets="all" />
+    <PackageReference Condition="'$(MultiTargetPlatformIdentifier)' == 'windows'" Include="Microsoft.Windows.CsWinRT" Version="2.1.6" PrivateAssets="all" />
 
     <!-- Temp workaround until next Windows SDK servicing update -->
-    <PackageReference Condition="'$(HasWinUI)' == 'true' AND '$(IsWindowsTfm)' == 'true'" Include="Microsoft.Windows.SDK.CPP" Version="10.0.26100.2454" PrivateAssets="all" />
+    <PackageReference Condition="'$(HasWinUI)' == 'true' AND '$(MultiTargetPlatformIdentifier)' == 'windows'" Include="Microsoft.Windows.SDK.CPP" Version="10.0.26100.2454" PrivateAssets="all" />
   </ItemGroup>
 </Project>

ProjectHeads/Head.Uwp.props

@@ -13,6 +13,7 @@
         <AppDesignerFolder>Properties</AppDesignerFolder>
         <DefaultLanguage>en-US</DefaultLanguage>
         <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+        <MultiTargetPlatformIdentifier>$(TargetPlatformIdentifier)</MultiTargetPlatformIdentifier>
         <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
         <FileAlignment>512</FileAlignment>
         <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>

ProjectHeads/Head.WinAppSdk.props

@@ -5,6 +5,7 @@
     <Platforms>x86;x64;arm64</Platforms>
     <PublishProfile>win-$(Platform).pubxml</PublishProfile>
     <UseWinUI>true</UseWinUI>
+    <MultiTargetPlatformIdentifier>windows</MultiTargetPlatformIdentifier>
     <EnablePreviewMsixTooling>true</EnablePreviewMsixTooling>
     <EnableMsixTooling>true</EnableMsixTooling>
     <WindowsAppContainer>true</WindowsAppContainer>