Use `$(TargetFrameworkIdentifier)` and `$(TargetFrameworkVersion)` consistently (#25428)

- always use `$([MSBuild]::VersionXYZ(...))` for version checks
- use `$(NETCoreAppFrameworkIdentifier)` where it's available
- move `$(KnownAppHostPackOrFrameworkReferenceTfm)` setting to Directory.Build.props
  - use it to correct `@(KnownFrameworkReference)` updates
  - metadata of those items still uses `netcoreapp5.0`
  - see also https://github.com/dotnet/efcore/pull/22279#discussion_r478674176

nits:
- do not assume `$(TargetFrameworkVersion)` starts with a 'v'; valid w/o it
- add `$(_IsMicrosoftNETCoreApp20OrOlder)` property in OpenAPI targets file
  - evaluate the `Condition` once instead of three times

Directory.Build.targets

@@ -134,14 +134,20 @@
     <AssemblyVersion>$(AspNetCoreMajorVersion).$(AspNetCoreMinorVersion).0.0</AssemblyVersion>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <KnownAppHostPackOrFrameworkReferenceTfm>$(DefaultNetCoreTargetFramework)</KnownAppHostPackOrFrameworkReferenceTfm>
+    <KnownAppHostPackOrFrameworkReferenceTfm Condition=" '$(TargetFrameworkIdentifier)' == '$(NETCoreAppFrameworkIdentifier)' AND
+      $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '5.0')) ">netcoreapp$(TargetFrameworkVersion.TrimStart('vV'))</KnownAppHostPackOrFrameworkReferenceTfm>
+  </PropertyGroup>
+
   <ItemGroup>
     <KnownFrameworkReference Update="Microsoft.NETCore.App">
       <!-- Always update the 'latest version', whether the repo is servicing or not. -->
-      <LatestRuntimeFrameworkVersion Condition="'%(TargetFramework)' == '$(DefaultNetCoreTargetFramework)'">$(MicrosoftNETCoreAppRuntimeVersion)</LatestRuntimeFrameworkVersion>
+      <LatestRuntimeFrameworkVersion Condition="'%(TargetFramework)' == '$(KnownAppHostPackOrFrameworkReferenceTfm)'">$(MicrosoftNETCoreAppRuntimeVersion)</LatestRuntimeFrameworkVersion>
       <!-- Only update the default runtime version for preview builds. -->
-      <DefaultRuntimeFrameworkVersion Condition="'%(TargetFramework)' == '$(DefaultNetCoreTargetFramework)' and '$(IsServicingBuild)' != 'true'">$(MicrosoftNETCoreAppRuntimeVersion)</DefaultRuntimeFrameworkVersion>
+      <DefaultRuntimeFrameworkVersion Condition="'%(TargetFramework)' == '$(KnownAppHostPackOrFrameworkReferenceTfm)' and '$(IsServicingBuild)' != 'true'">$(MicrosoftNETCoreAppRuntimeVersion)</DefaultRuntimeFrameworkVersion>
       <!-- Only update the targeting pack version for preview builds. -->
-      <TargetingPackVersion Condition="'%(TargetFramework)' == '$(DefaultNetCoreTargetFramework)' and '$(IsServicingBuild)' != 'true'">$(MicrosoftNETCoreAppRefPackageVersion)</TargetingPackVersion>
+      <TargetingPackVersion Condition="'%(TargetFramework)' == '$(KnownAppHostPackOrFrameworkReferenceTfm)' and '$(IsServicingBuild)' != 'true'">$(MicrosoftNETCoreAppRefPackageVersion)</TargetingPackVersion>
     </KnownFrameworkReference>
 
     <KnownFrameworkReference Condition="'$(UseAspNetCoreSharedRuntime)' != 'true'" Remove="Microsoft.AspNetCore.App" />

eng/Workarounds.targets

@@ -22,7 +22,9 @@
   <ItemGroup>
     <FrameworkReference Remove="Microsoft.AspNetCore.App" Condition="'$(DoNotApplyWorkaroundsToMicrosoftAspNetCoreApp)' != 'true'" />
     <!-- Required because the Razor SDK will generate attributes -->
-    <Reference Include="Microsoft.AspNetCore.Mvc" Condition="'$(UsingMicrosoftNETSdkWeb)' == 'true' AND '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(GenerateRazorAssemblyInfo)' == 'true'" />
+    <Reference Include="Microsoft.AspNetCore.Mvc" Condition="'$(UsingMicrosoftNETSdkWeb)' == 'true' AND
+      '$(TargetFrameworkIdentifier)' == '$(NETCoreAppFrameworkIdentifier)' AND
+      '$(GenerateRazorAssemblyInfo)' == 'true'" />
   </ItemGroup>
 
   <!-- Workaround https://github.com/dotnet/aspnetcore/issues/7503. This chains GenerateSourceLinkFile before razor component targets run. -->
@@ -40,11 +42,6 @@
     <PackageReference Include="Internal.AspNetCore.BuildTasks" PrivateAssets="All" Version="$(InternalAspNetCoreBuildTasksPackageVersion)" IsImplicitlyDefined="true" />
   </ItemGroup>
 
-  <PropertyGroup>
-    <KnownAppHostPackOrFrameworkReferenceTfm>$(DefaultNetCoreTargetFramework)</KnownAppHostPackOrFrameworkReferenceTfm>
-    <KnownAppHostPackOrFrameworkReferenceTfm Condition="'$(KnownAppHostPackOrFrameworkReferenceTfm)' == 'net5.0'">netcoreapp5.0</KnownAppHostPackOrFrameworkReferenceTfm>
-  </PropertyGroup>
-
   <ItemGroup>
     <!-- Workaround when there is no vNext SDK available, copy known apphost/framework reference info from 3.1 -->
     <KnownAppHostPack

eng/targets/CSharp.Common.targets

@@ -2,7 +2,7 @@
 
   <!-- For 'legacy' .csproj files, set map TargetFrameworkVersion back to TargetFramework -->
   <PropertyGroup Condition=" '$(TargetFramework)' == '' AND '$(TargetFrameworks)' == '' ">
-    <TargetFramework>net$(TargetFrameworkVersion.Substring(1).Replace('.',''))</TargetFramework>
+    <TargetFramework>net$(TargetFrameworkVersion.TrimStart('vV').Replace('.',''))</TargetFramework>
     <TargetFrameworkIdentifier>.NETFramework</TargetFrameworkIdentifier>
   </PropertyGroup>
 

src/Razor/Microsoft.NET.Sdk.Razor/src/build/netstandard2.0/Sdk.Razor.CurrentVersion.targets

@@ -38,9 +38,10 @@ Copyright (c) .NET Foundation. All rights reserved.
 
   <!-- Resolve the RazorLangVersion based on values imported or TFM. -->
   <PropertyGroup>
-    <_TargetFrameworkVersionWithoutV>$(TargetFrameworkVersion.TrimStart('vV'))</_TargetFrameworkVersionWithoutV>
-    <_TargetingNETCoreApp30OrLater Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(_TargetFrameworkVersionWithoutV)' >= '3.0'">true</_TargetingNETCoreApp30OrLater>
-    <_TargetingNET50OrLater Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(_TargetFrameworkVersionWithoutV)' >= '5.0'">true</_TargetingNET50OrLater>
+    <_TargetingNETCoreApp30OrLater Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND
+      $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '3.0')) ">true</_TargetingNETCoreApp30OrLater>
+    <_TargetingNET50OrLater Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND
+      $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '5.0')) ">true</_TargetingNET50OrLater>
 
     <!--
       Infer the RazorLangVersion if no value was specified. When adding support for newer target frameworks, list newer language versions first.
@@ -227,7 +228,10 @@ Copyright (c) .NET Foundation. All rights reserved.
     <CopyRefAssembliesToPublishDirectory Condition="'$(CopyRefAssembliesToPublishDirectory)'==''">$(PreserveCompilationReferences)</CopyRefAssembliesToPublishDirectory>
 
     <!-- For 2.x projects desktop and .NET Core projects, if they're opting in to runtime compilation (indicated by PreserveCompilationContext=true), set PreserveCompilationReferences = true -->
-    <PreserveCompilationReferences Condition="'$(PreserveCompilationContext)' == 'true' AND (('$(TargetFrameworkIdentifier)' == '.NETFramework') OR ('$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(_TargetFrameworkVersionWithoutV)' &lt; '3.0'))">true</PreserveCompilationReferences>
+    <PreserveCompilationReferences Condition=" '$(PreserveCompilationContext)' == 'true' AND
+      ('$(TargetFrameworkIdentifier)' == '.NETFramework' OR
+       ('$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND
+        '$(_TargetingNETCoreApp30OrLater)' != 'true')) ">true</PreserveCompilationReferences>
 
     <!--
       We can't set the actual default value here due to evaluation order (depends on $(OutDir)).

src/Tools/Extensions.ApiDescription.Server/src/build/Microsoft.Extensions.ApiDescription.Server.targets

@@ -1,9 +1,13 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <Project>
+  <PropertyGroup>
+    <_IsMicrosoftNETCoreApp20OrOlder>false</_IsMicrosoftNETCoreApp20OrOlder>
+    <_IsMicrosoftNETCoreApp20OrOlder Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND
+      $([MSBuild]::VersionLessThanOrEquals('$(TargetFrameworkVersion)', '2.0') ">true</_IsMicrosoftNETCoreApp20OrOlder>
+  </PropertyGroup>
   <PropertyGroup Condition=" '$(OpenApiGenerateDocuments)' == '' ">
     <OpenApiGenerateDocuments>true</OpenApiGenerateDocuments>
-    <OpenApiGenerateDocuments
-        Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(TargetFrameworkVersion.TrimStart(&quot;vV&quot;))' &lt; '2.1' " />
+    <OpenApiGenerateDocuments Condition=" $(_IsMicrosoftNETCoreApp20OrOlder) " />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(OpenApiGenerateDocumentsOnBuild)' == '' ">
     <OpenApiGenerateDocumentsOnBuild>$(OpenApiGenerateDocuments)</OpenApiGenerateDocumentsOnBuild>
@@ -22,7 +26,7 @@
         Text="OpenAPI document generation is disabled. Add '&lt;OpenApiGenerateDocuments>true&lt;/OpenApiGenerateDocuments>' to the project." />
     <!-- E.g. project set $(OpenApiGenerateDocuments) to 'true' but TFM is not supported. -->
     <Error
-        Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(TargetFrameworkVersion.TrimStart(&quot;vV&quot;))' &lt; '2.1' "
+        Condition=" $(_IsMicrosoftNETCoreApp20OrOlder) "
         Text="OpenAPI document generation is not supported when targeting netcoreapp2.0 or earlier. Disable the feature or move to a later target framework." />
     <!-- E.g. project set $(OpenApiGenerateDocumentsOnBuild) to 'false' but did not invoke GenerateOpenApiDocuments. -->
     <Error Condition=" !Exists('$(_OpenApiDocumentsCache)' )"
@@ -43,7 +47,7 @@
         Text="OpenAPI document generation is disabled. Add '&lt;OpenApiGenerateDocuments>true&lt;/OpenApiGenerateDocuments>' to the project." />
     <!-- E.g. project sets $(OpenApiGenerateDocuments) to 'true' but TFM is not supported. -->
     <Error
-        Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(TargetFrameworkVersion.TrimStart(&quot;vV&quot;))' &lt; '2.1' "
+        Condition=" $(_IsMicrosoftNETCoreApp20OrOlder) "
         Text="OpenAPI document generation is not supported when targeting netcoreapp2.0 or earlier. Disable the feature or move to a later target framework." />
 
     <PropertyGroup>

src/Tools/dotnet-watch/src/assets/DotNetWatch.targets

@@ -11,8 +11,8 @@ them to a file.
           DependsOnTargets="_CollectWatchItems">
 
     <PropertyGroup>
-      <_IsMicrosoftNETCoreApp31OrNewer
-          Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And $([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), '3.1'))">true</_IsMicrosoftNETCoreApp31OrNewer>
+      <_IsMicrosoftNETCoreApp31OrNewer Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND
+        $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '3.1'))">true</_IsMicrosoftNETCoreApp31OrNewer>
 
       <_IsMicrosoftNETCoreApp31OrNewer Condition="'$(_IsMicrosoftNETCoreApp31OrNewer)' == ''">false</_IsMicrosoftNETCoreApp31OrNewer>
     </PropertyGroup>