[build] Update to net9.0 and netstandard2.0 (#251)

Introduces a `$(DotNetTargetFramework)` property to control the target
framework version used for exe projects, and sets it to the latest
stable .NET version (`net9.0`).

Library and build task projects have been updated to only target
`netstandard2.0`, which is compatible with both .NET Framework and .NET
Core.

Author: pjcollins

Directory.Build.props

@@ -5,6 +5,8 @@
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <!-- Disables the transitive restore of packages like Microsoft.AspNetCore.App.Ref, Microsoft.WindowsDesktop.App.Ref -->
     <DisableTransitiveFrameworkReferenceDownloads>true</DisableTransitiveFrameworkReferenceDownloads>
+    <DotNetTargetFrameworkVersion>9.0</DotNetTargetFrameworkVersion>
+    <DotNetTargetFramework>net$(DotNetTargetFrameworkVersion)</DotNetTargetFramework>
   </PropertyGroup>
   <Import
       Project="$(MSBuildThisFileDirectory)Configuration.Override.props"
@@ -16,17 +18,6 @@
   />
   <PropertyGroup>
     <BaseIntermediateOutputPath Condition=" '$(BaseIntermediateOutputPath)' == '' ">obj\</BaseIntermediateOutputPath>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(TargetFramework)' != '' and '$(TargetFramework)' != 'net472' and '$(TargetFramework)' != 'netstandard2.0' ">
-    <XATBuildingForNetCoreApp>True</XATBuildingForNetCoreApp>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(XATBuildingForNetCoreApp)' == 'True' ">
-    <IntermediateOutputPath>$(BaseIntermediateOutputPath)\$(Configuration)-$(TargetFramework.ToLowerInvariant())</IntermediateOutputPath>
-    <BuildToolOutputFullPath>$(MSBuildThisFileDirectory)bin\Build$(Configuration)\$(TargetFramework.ToLowerInvariant())\</BuildToolOutputFullPath>
-    <ToolOutputFullPath>$(MSBuildThisFileDirectory)bin\$(Configuration)\$(TargetFramework.ToLowerInvariant())\</ToolOutputFullPath>
-    <TestOutputFullPath>$(MSBuildThisFileDirectory)bin\Test$(Configuration)-$(TargetFramework.ToLowerInvariant())\</TestOutputFullPath>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(XATBuildingForNetCoreApp)' != 'True' ">
     <IntermediateOutputPath>$(BaseIntermediateOutputPath)\$(Configuration)</IntermediateOutputPath>
     <BuildToolOutputFullPath>$(MSBuildThisFileDirectory)bin\Build$(Configuration)\</BuildToolOutputFullPath>
     <ToolOutputFullPath>$(MSBuildThisFileDirectory)bin\$(Configuration)\</ToolOutputFullPath>

azure-pipelines.yaml

@@ -46,7 +46,7 @@ jobs:
     displayName: Run Tests
     inputs:
       command: test
-      projects: bin/TestDebug-net*/**/*-Tests.dll
+      projects: bin/TestDebug/**/*-Tests.dll
 
   - powershell: |
       $hashOfLastVersionChange = & "git" "log" "--follow" "-1" "--pretty=%H" "nuget.version"

src/Microsoft.Android.Build.BaseTasks/Microsoft.Android.Build.BaseTasks.csproj

@@ -3,7 +3,7 @@
   <Import Project="MSBuildReferences.projitems" />
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Microsoft.Android.Build.Tasks</RootNamespace>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <SignAssembly>true</SignAssembly>

src/Xamarin.Android.Tools.AndroidSdk/Xamarin.Android.Tools.AndroidSdk.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <LangVersion>8.0</LangVersion>
     <Nullable>enable</Nullable>
     <DefineConstants>INTERNAL_NULLABLE_ATTRIBUTES</DefineConstants>
@@ -17,10 +17,6 @@
     <AssemblyName>$(VendorPrefix)Xamarin.Android.Tools.AndroidSdk$(VendorSuffix)</AssemblyName>
   </PropertyGroup>
 
-  <ItemGroup>
-    <Compile Condition=" '$(TargetFramework)' != 'netstandard2.0' " Remove="NullableAttributes.cs" />
-  </ItemGroup>
-
   <PropertyGroup>
     <OutputPath>$(ToolOutputFullPath)</OutputPath>
   </PropertyGroup>

tests/Microsoft.Android.Build.BaseTasks-Tests/Microsoft.Android.Build.BaseTasks-Tests.csproj

@@ -1,10 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <!-- $(TargetFrameworks) is used to allow the $(TargetFramework) check in Directory.Build.props to work.
-        If $(TargetFramework) is declared here instead, it will not be evaluated before Directory.Build.props
-        is loaded and the wrong $(TestOutputFullPath) will be used. -->
-    <TargetFrameworks>net8.0</TargetFrameworks>
+    <TargetFramework>$(DotNetTargetFramework)</TargetFramework>
     <RootNamespace>Microsoft.Android.Build.BaseTasks.Tests</RootNamespace>
     <IsPackable>false</IsPackable>
     <OutputPath>$(TestOutputFullPath)</OutputPath>

tests/Xamarin.Android.Tools.AndroidSdk-Tests/Xamarin.Android.Tools.AndroidSdk-Tests.csproj

@@ -1,10 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <!-- $(TargetFrameworks) is used to allow the $(TargetFramework) check in Directory.Build.props to work.
-        If $(TargetFramework) is declared here instead, it will not be evaluated before Directory.Build.props
-        is loaded and the wrong $(TestOutputFullPath) will be used. -->
-    <TargetFrameworks>net8.0</TargetFrameworks>
+    <TargetFramework>$(DotNetTargetFramework)</TargetFramework>
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>..\..\product.snk</AssemblyOriginatorKeyFile>
     <IsPackable>false</IsPackable>

tools/ls-jdks/ls-jdks.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFrameworks>net472;net6.0</TargetFrameworks>
+    <TargetFramework>$(DotNetTargetFramework)</TargetFramework>
     <RootNamespace>Xamarin.Android.Tools</RootNamespace>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <OutputPath>$(ToolOutputFullPath)</OutputPath>