Refactor the platform support attribute generation in the build

eng/targetframeworksuffix.props

@@ -1,18 +1,21 @@
 <Project>
-  
+
   <PropertyGroup>
     <TargetPlatformSupported>true</TargetPlatformSupported>
     <TargetPlatformVersionSupported>true</TargetPlatformVersionSupported>
+
+    <!-- Value of 0.0 produces versionless SupportedOSPlatform attribute.
+         This is required for platforms not expected to have a version,
+         and we currently omit the version for all platforms. -->
+    <SupportedOSPlatformVersion>0.0</SupportedOSPlatformVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(TargetFrameworkSuffix)' != '' and '$(TargetFrameworkSuffix)' != 'windows'">
     <TargetPlatformIdentifier>$(TargetFrameworkSuffix)</TargetPlatformIdentifier>
     <TargetPlatformVersion>1.0</TargetPlatformVersion>
     <TargetPlatformMoniker>$(TargetFrameworkSuffix),Version=$(TargetPlatformVersion)</TargetPlatformMoniker>
-    <!-- Value of 0.0 produces versionless SupportedOSPlatform attribute, which is important for platforms not expected to have a version -->
-    <SupportedOSPlatformVersion>0.0</SupportedOSPlatformVersion>
   </PropertyGroup>
-  
+
   <Choose>
     <When Condition="'$(TargetFrameworkSuffix)' == 'windows'">
       <PropertyGroup>

eng/versioning.targets

@@ -25,13 +25,6 @@
     </AssemblyMetadata>
   </ItemGroup>
 
-  <!-- Adds SupportedOSPlatform attribute for Windows Specific libraries -->
-  <ItemGroup Condition="'$(IsWindowsSpecific)' == 'true' and '$(IsTestProject)' != 'true' and '$(IncludePlatformAttributes)' != 'false'">
-    <AssemblyAttribute Include="System.Runtime.Versioning.SupportedOSPlatform">
-        <_Parameter1>windows</_Parameter1>
-    </AssemblyAttribute>
-  </ItemGroup>
-
   <PropertyGroup Condition="'$(TargetsAnyOS)' == 'true' and !$(TargetFrameworks.Contains('$(TargetFramework)-Browser'))">
       <CrossPlatformAndHasNoBrowserTarget>true</CrossPlatformAndHasNoBrowserTarget>
   </PropertyGroup>
@@ -57,29 +50,37 @@
     <SupportedPlatform Condition="'$(TargetsUnix)' == 'true'" Include="Unix"/>
   </ItemGroup>
 
-  <ItemGroup>
-    <_unsupportedOSPlatforms Include="$(UnsupportedOSPlatforms)" />
-    <_supportedOSPlatforms Include="$(SupportedOSPlatforms)" />
-  </ItemGroup>
-
   <!-- Adds UnsupportedOSPlatform and SupportedOSPlatform attributes to the assembly when:
-      * At least one <UnsupportedOSPlatforms /> or <SupportedOSPlatforms /> has been specified
       * This isn't a test project
       * This is a cross-platform target
       * The build isn't targeting .NET Framework
     -->
   <Target Name="AddOSPlatformAttributes" BeforeTargets="GenerateAssemblyInfo" AfterTargets="PrepareForBuild"
     Condition="'$(TargetsAnyOS)' == 'true' and '$(IsTestProject)' != 'true' and '$(TargetFrameworkIdentifier)' != '.NETFramework'">
+    <!-- Defensively de-dupe the values -->
+    <ItemGroup>
+      <_unsupportedOSPlatforms Include="$(UnsupportedOSPlatforms)" />
+      <_supportedOSPlatforms Include="$(SupportedOSPlatforms)" />
+    </ItemGroup>
+
     <ItemGroup Condition="'@(_unsupportedOSPlatforms)' != ''">
+      <!-- Add the assembly attribute -->
       <AssemblyAttribute Include="System.Runtime.Versioning.UnsupportedOSPlatform">
         <_Parameter1>%(_unsupportedOSPlatforms.Identity)</_Parameter1>
       </AssemblyAttribute>
+
+      <!-- Ensure this platform is included in the platforms enabled for the CA1416 analyzer -->
+      <SupportedPlatform Include="%(_unsupportedOSPlatforms.Identity)" />
     </ItemGroup>
 
     <ItemGroup Condition="'@(_supportedOSPlatforms)' != ''">
+      <!-- Add the assembly attribute -->
       <AssemblyAttribute Include="System.Runtime.Versioning.SupportedOSPlatform">
         <_Parameter1>%(_supportedOSPlatforms.Identity)</_Parameter1>
       </AssemblyAttribute>
+
+      <!-- Ensure this platform is included in the platforms enabled for the CA1416 analyzer -->
+      <SupportedPlatform Include="%(_supportedOSPlatforms.Identity)" />
     </ItemGroup>
   </Target>
 

src/libraries/Directory.Build.targets

@@ -133,12 +133,12 @@
     <PropertyGroup>
       <_ExcludeAPIList>$([MSBuild]::NormalizePath('$(MSBuildProjectDirectory)', '..', 'ref', 'ReferenceSourceExcludeApi.txt'))</_ExcludeAPIList>
       <_ExcludeAttributesList>$(RepositoryEngineeringDir)DefaultGenApiDocIds.txt</_ExcludeAttributesList>
-      <_LicenseHeaderTxtPath>$(RepositoryEngineeringDir)LicenseHeader.txt</_LicenseHeaderTxtPath> 
+      <_LicenseHeaderTxtPath>$(RepositoryEngineeringDir)LicenseHeader.txt</_LicenseHeaderTxtPath>
       <GenAPITargetPath>$([MSBuild]::NormalizePath('$(MSBuildProjectDirectory)', '..', 'ref', '$(AssemblyName).cs'))</GenAPITargetPath>
       <GenAPIAdditionalParameters>$(GenAPIAdditionalParameters) --exclude-attributes-list "$(_ExcludeAttributesList)"</GenAPIAdditionalParameters>
       <GenAPIAdditionalParameters Condition="Exists('$(_ExcludeAPIList)')">$(GenAPIAdditionalParameters) --exclude-api-list "$(_ExcludeAPIList)"</GenAPIAdditionalParameters>
       <GenAPIAdditionalParameters>$(GenAPIAdditionalParameters) --header-file "$(_LicenseHeaderTxtPath)"</GenAPIAdditionalParameters>
-      <GenAPIAdditionalParameters Condition="'$(LangVersion)' != ''">$(GenAPIAdditionalParameters) --lang-version "$(LangVersion)"</GenAPIAdditionalParameters>  
+      <GenAPIAdditionalParameters Condition="'$(LangVersion)' != ''">$(GenAPIAdditionalParameters) --lang-version "$(LangVersion)"</GenAPIAdditionalParameters>
       <GenAPIAdditionalParameters Condition="'%(ProjectReference.Identity)' == '$(CoreLibProject)'">$(GenAPIAdditionalParameters) --follow-type-forwards</GenAPIAdditionalParameters>
     </PropertyGroup>
   </Target>
@@ -232,7 +232,10 @@
   <!-- Adds System.Runtime.Versioning*Platform* annotation attributes to < .NET 5 builds -->
   <Choose>
     <When Condition="'$(IncludePlatformAttributes)' == 'false'" />
-    <When Condition="('$(IncludePlatformAttributes)' == 'true' or '$(IsWindowsSpecific)' == 'true') and ('$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '5.0')))">
+    <When Condition="('$(IncludePlatformAttributes)' == 'true' or '$(SupportedOSPlatforms)' != '' or '$(UnsupportedOSPlatforms)' != '') and ('$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan($(TargetFrameworkVersion), '5.0')))">
+      <!-- If a project is downlevel from net5.0 but uses the platform support attributes, then we include the classes
+           in the project as internal. If a project has specified assembly-level SupportedOSPlatforms or UnsupportedOSPlatforms,
+           we can infer the need without having IncludePlatformAttributes set. -->
       <ItemGroup>
         <Compile Include="$(CoreLibSharedDir)System\Runtime\Versioning\PlatformAttributes.cs" Link="System\Runtime\Versioning\PlatformAttributes.cs" />
       </ItemGroup>

src/libraries/Microsoft.Win32.Registry.AccessControl/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides support for managing access and audit control lists for Microsoft.Win32.RegistryKey.
 
 Commonly Used Types:

src/libraries/Microsoft.Win32.Registry/Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides support for accessing and modifying the Windows Registry.
 
 Commonly Used Types:

src/libraries/Microsoft.Win32.SystemEvents/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides access to Windows system event notifications.
 
 Commonly Used Types:

src/libraries/System.Data.OleDb/Directory.Build.props

@@ -1,7 +1,7 @@
 <Project>
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides a collection of classes for OLEDB.
 
 Commonly Used Types:

src/libraries/System.Diagnostics.EventLog/Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides the System.Diagnostics.EventLog class, which allows the applications to use the windows event log service.
 
 Commonly Used Types:

src/libraries/System.Diagnostics.EventLog/src/Messages/System.Diagnostics.EventLog.Messages.csproj

@@ -2,6 +2,7 @@
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
     <Win32Resource>EventLogMessages.res</Win32Resource>
-    <IncludePlatformAttributes>false</IncludePlatformAttributes>
+    <!-- Override the parent Directory.Build.props -->
+    <SupportedOSPlatforms />
   </PropertyGroup>
 </Project>

src/libraries/System.Diagnostics.PerformanceCounter/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides the System.Diagnostics.PerformanceCounter class, which allows access to Windows performance counters.
 
 Commonly Used Types:

src/libraries/System.DirectoryServices.AccountManagement/Directory.Build.props

@@ -6,7 +6,7 @@
          to a different assembly. -->
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <StrongNameKeyId>ECMA</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides uniform access and manipulation of user, computer, and group security principals across the multiple principal stores: Active Directory Domain Services (AD DS), Active Directory Lightweight Directory Services (AD LDS), and Machine SAM (MSAM).</PackageDescription>
   </PropertyGroup>
 </Project>

src/libraries/System.DirectoryServices/Directory.Build.props

@@ -6,7 +6,7 @@
          to a different assembly. -->
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides easy access to Active Directory Domain Services.
 
 Commonly Used Types:

src/libraries/System.IO.FileSystem.AccessControl/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides types for managing access and audit control lists for files and directories.
 
 Commonly Used Types:

src/libraries/System.IO.Pipes.AccessControl/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides types for managing access and audit control lists for pipes.
 
 Commonly Used Types:

src/libraries/System.Management/Directory.Build.props

@@ -6,7 +6,7 @@
          to a different assembly. -->
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides access to a rich set of management information and management events about the system, devices, and applications instrumented to the Windows Management Instrumentation (WMI) infrastructure.
 
 Commonly Used Types:

src/libraries/System.Net.Http.WinHttpHandler/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides a message handler for HttpClient based on the WinHTTP interface of Windows. While similar to HttpClientHandler, it provides developers more granular control over the application's HTTP communication than the HttpClientHandler.
 
 Commonly Used Types:

src/libraries/System.Security.AccessControl/Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides base classes that enable managing access and audit control lists on securable objects.
 
 Commonly Used Types:

src/libraries/System.Security.Cryptography.Cng/Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides cryptographic algorithm implementations and key management with Windows Cryptographic Next Generation API (CNG).
 
 Commonly Used Types:

src/libraries/System.Security.Cryptography.ProtectedData/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides access to Windows Data Protection Api.
 
 Commonly Used Types:

src/libraries/System.Security.Principal.Windows/Directory.Build.props

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides classes for retrieving the current Windows user and for interacting with Windows users and groups.
 
 Commonly Used Types:

src/libraries/System.ServiceProcess.ServiceController/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides the System.ServiceProcess.ServiceContainer class, which allows you to connect to a running or stopped service, manipulate it, or get information about it.
 
 Commonly Used Types:

src/libraries/System.Speech/Directory.Build.props

@@ -6,7 +6,7 @@
          to a different assembly. -->
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <StrongNameKeyId>MicrosoftShared</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides types to perform speech synthesis and speech recognition.
 
 Commonly Used Types

src/libraries/System.Threading.AccessControl/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides support for managing access and audit control lists for synchronization primitives.
 
 Commonly Used Types:

src/libraries/System.Threading.Overlapped/Directory.Build.props

@@ -2,6 +2,6 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
   </PropertyGroup>
 </Project>

src/libraries/System.Windows.Extensions/Directory.Build.props

@@ -2,7 +2,7 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <StrongNameKeyId>Open</StrongNameKeyId>
-    <IsWindowsSpecific>true</IsWindowsSpecific>
+    <SupportedOSPlatforms>windows</SupportedOSPlatforms>
     <PackageDescription>Provides miscellaneous Windows-specific types
 
 Commonly Used Types: