[One .NET] support building net6.0-android apps in .NET 7 (#6988)

We currently have a hard dependency between:

  * `Xamarin.Android.Build.Tasks.dll`
  * `libmonodroid.so`

The design for building a `net6.0-android` app with a .NET 7 SDK
results in us using a .NET 7 `Xamarin.Android.Builds.Tasks.dll` and a
.NET 6 `libmonodroid.so`.  This crashes with:

	E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed:
	cannot locate symbol "java_name_width" referenced by
	"/data/app/~~8CHtXY8wK4g7s9VcOLTQEg==/com.microsoft.net6.helloandroid-cUUhwuQls7TRb6JdBsbPdg==/split_config.arm64_v8a.apk!/lib/arm64-v8a/libmonodroid.so"...

To solve this problem:

  * Define `$(AndroidNet6Version)` to specify our .NET 6 GA
    `32.0.301` build that is released.

  * Add an alias for a `Microsoft.Android.Sdk.$(HostOS).NET6`
    workload pack that loads a .NET 6 version of
    `Microsoft.Android.Sdk.$(HostOS)`.

  * Include both the .NET 6 and .NET 7 versions of these packs in the
    workload.

  * Check `$(TargetFrameworkVersion)` and import the .NET 7 or .NET 6
    MSBuild targets when appropriate.

  * Update `@(KnownFrameworkReference)` to the version of .NET 6
    that our .NET 7 packs know about.

  * We have a matching .NET 6 `Xamarin.Android.Build.Tasks.dll` and
    `libmonodroid.so`!

This obviously increases our install footprint of
`Microsoft.Android.Sdk.$(HostOS)` by 2x.  We might be able to address
this by splitting out some files into a
`Microsoft.Android.Sdk.Tooling` pack that can be shared between
.NET 6 and .NET 7.  (Perhaps files like `bundletool.jar` and `r8.jar`
could be shared?)

One hack I had to put in place was to avoid the crash:

	E AndroidRuntime: java.lang.UnsatisfiedLinkError: dlopen failed:
	cannot locate symbol "mono_opt_aot_lazy_assembly_load" referenced by
	"/data/app/~~Fp4gEr_9sxU1qU6PoI-v6Q==/com.companyname.foo-EKEtL67XJI-d0H17_3oz3g==/lib/arm64/libmonodroid.so"...

The .NET 7 SDK we are on does not yet know about .NET runtime 6.0.5
(it uses 6.0.3), so I manually fixed this version number for now.
We should be able to remove this eventually when the .NET 7 SDK
provides 6.0.5 by default.

A second hack I put in place:

Make `Microsoft.Android.Sdk.NET6` a "framework" and not an "sdk"
within `WorkloadManifest.json`.  This prevents *both* the .NET 6
`AutoImport.props` *and* .NET 7 `AutoImport.props` files from being
imported, causing duplication of item groups/etc.

This seems very weird, but this still works:

	<Import Project="Sdk.targets" Sdk="Microsoft.Android.Sdk" />

We can remove this if I condition everything in `AutoImport.props`
behind a current `$(TargetFrameworkVersion)`.  We would then need to
ship this in a .NET 6 release.

Author: jonathanpeppers

Configuration.props

@@ -47,6 +47,7 @@
     <DebugType Condition=" '$(DebugType)' == '' ">portable</DebugType>
     <Deterministic Condition=" '$(Deterministic)' == '' ">True</Deterministic>
     <LangVersion Condition=" '$(LangVersion)' == '' ">latest</LangVersion>
+    <AndroidNet6Version Condition=" '$(AndroidNet6Version)' == '' ">32.0.301</AndroidNet6Version>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(HostOS)' == '' ">
     <HostOS Condition="$([MSBuild]::IsOSPlatform('windows'))">Windows</HostOS>

build-tools/create-packs/Directory.Build.targets

@@ -123,6 +123,8 @@
     </PropertyGroup>
     <ItemGroup>
       <_NuGetSources Include="$(OutputPath.TrimEnd('\'))" />
+      <!-- This allows us to install our Android .NET 6 packs -->
+      <_NuGetSources Include="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
       <_PreviewPacks Condition=" '$(AndroidLatestStableApiLevel)' != '$(AndroidLatestUnstableApiLevel)' " Include="$(XamarinAndroidSourcePath)bin\Build$(Configuration)\nuget-unsigned\Microsoft.Android.Ref.$(AndroidLatestUnstableApiLevel).*.nupkg" />
       <_InstallArguments Include="android" />
       <_InstallArguments Include="android-$(AndroidLatestUnstableApiLevel)" Condition=" '@(_PreviewPacks->Count())' != '0' " />

build-tools/create-packs/Microsoft.NET.Sdk.Android.proj

@@ -28,18 +28,24 @@ about the various Microsoft.Android workloads.
       DependsOnTargets="_GetDefaultPackageVersion;_GetLicense">
     <PropertyGroup>
       <WorkloadManifestJsonPath>$(OutputPath)workload-manifest\WorkloadManifest.json</WorkloadManifestJsonPath>
+      <WorkloadManifestTargetsPath>$(OutputPath)workload-manifest\WorkloadManifest.targets</WorkloadManifestTargetsPath>
     </PropertyGroup>
 
-    <MakeDir Directories="$([System.IO.Path]::GetDirectoryName ($(WorkloadManifestJsonPath)))" />
+    <MakeDir Directories="$(OutputPath)workload-manifest" />
     <ReplaceFileContents
         SourceFile="$(XamarinAndroidSourcePath)src\Xamarin.Android.Build.Tasks\Microsoft.NET.Sdk.Android\WorkloadManifest.in.json"
         DestinationFile="$(WorkloadManifestJsonPath)"
-        Replacements="@WORKLOAD_VERSION@=$(AndroidPackVersionLong)">
+        Replacements="@WORKLOAD_VERSION@=$(AndroidPackVersionLong);@NET6_VERSION@=$(AndroidNet6Version)">
+    </ReplaceFileContents>
+    <ReplaceFileContents
+        SourceFile="$(XamarinAndroidSourcePath)src\Xamarin.Android.Build.Tasks\Microsoft.NET.Sdk.Android\WorkloadManifest.in.targets"
+        DestinationFile="$(WorkloadManifestTargetsPath)"
+        Replacements="@NET6_VERSION@=$(AndroidNet6Version)">
     </ReplaceFileContents>
 
     <ItemGroup>
-      <_PackageFiles Include="$(XamarinAndroidSourcePath)src\Xamarin.Android.Build.Tasks\Microsoft.NET.Sdk.Android\WorkloadManifest.targets" PackagePath="data" />
       <_PackageFiles Include="$(WorkloadManifestJsonPath)" PackagePath="data" />
+      <_PackageFiles Include="$(WorkloadManifestTargetsPath)" PackagePath="data" />
     </ItemGroup>
   </Target>
 

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/in/Microsoft.Android.Sdk.BundledVersions.in.targets

@@ -18,18 +18,6 @@ WARNING:  DO NOT MODIFY this file unless you are knowledgeable about MSBuild and
     <_AndroidRuntimePackId Condition=" '$(_AndroidRuntimePackId)' == '' ">$(_AndroidTargetingPackId)</_AndroidRuntimePackId>
   </PropertyGroup>
   <ItemGroup>
-    <!-- TODO: NET7TODO: Is this the right way to support building net6.0 projects? Need to bump versions as packages are release to NuGet.org as well -->
-    <KnownFrameworkReference
-        Include="Microsoft.Android"
-        TargetFramework="net6.0"
-        RuntimeFrameworkName="Microsoft.Android"
-        LatestRuntimeFrameworkVersion="32.0.300-rc.1.4"
-        TargetingPackName="Microsoft.Android.Ref.$(_AndroidTargetingPackId)"
-        TargetingPackVersion="32.0.300-rc.1.4"
-        RuntimePackNamePatterns="Microsoft.Android.Runtime.$(_AndroidRuntimePackId).**RID**"
-        RuntimePackRuntimeIdentifiers="android-arm;android-arm64;android-x86;android-x64"
-        Profile="Android"
-    />
     <KnownFrameworkReference
         Include="Microsoft.Android"
         TargetFramework="@DOTNET_TARGET_FRAMEWORK@"

src/Xamarin.Android.Build.Tasks/Microsoft.NET.Sdk.Android/WorkloadManifest.in.json

@@ -5,6 +5,7 @@
       "description": ".NET SDK Workload for building Android applications.",
       "packs": [
         "Microsoft.Android.Sdk",
+        "Microsoft.Android.Sdk.NET6",
         "Microsoft.Android.Ref.32",
         "Microsoft.Android.Runtime.32.android-arm",
         "Microsoft.Android.Runtime.32.android-arm64",
@@ -40,6 +41,17 @@
         "linux-x64": "Microsoft.Android.Sdk.Linux"
       }
     },
+    "Microsoft.Android.Sdk.NET6": {
+      "kind": "framework",
+      "version": "@NET6_VERSION@",
+      "alias-to": {
+        "osx-x64": "Microsoft.Android.Sdk.Darwin",
+        "osx-arm64": "Microsoft.Android.Sdk.Darwin",
+        "win-x86": "Microsoft.Android.Sdk.Windows",
+        "win-x64": "Microsoft.Android.Sdk.Windows",
+        "linux-x64": "Microsoft.Android.Sdk.Linux"
+      }
+    },
     "Microsoft.Android.Ref.32": {
       "kind": "framework",
       "version": "@WORKLOAD_VERSION@"

src/Xamarin.Android.Build.Tasks/Microsoft.NET.Sdk.Android/WorkloadManifest.in.targets

@@ -0,0 +1,26 @@
+<Project>
+  <ImportGroup Condition=" '$(TargetPlatformIdentifier)' == 'android' ">
+    <Import Project="Sdk.targets" Sdk="Microsoft.Android.Sdk"
+        Condition=" $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '7.0')) " />
+    <Import Project="Sdk.targets" Sdk="Microsoft.Android.Sdk.NET6"
+        Condition=" $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '6.0')) " />
+  </ImportGroup>
+
+  <ItemGroup Condition=" '$(TargetPlatformIdentifier)' == 'android' and $([MSBuild]::VersionEquals($(TargetFrameworkVersion), '6.0')) ">
+    <KnownFrameworkReference
+        Update="Microsoft.Android"
+        LatestRuntimeFrameworkVersion="@NET6_VERSION@"
+        TargetingPackVersion="@NET6_VERSION@"
+    />
+    <!--
+      HACK:
+      The .NET 7 SDK specifies 6.0.3 for .NET 6, but our .NET 6 libmonodroid.so depends on 6.0.5.
+      We should be able to remove this when we get a newer .NET 7 SDK.
+     -->
+    <KnownRuntimePack Update="Microsoft.NETCore.App" LatestRuntimeFrameworkVersion="6.0.5" />
+  </ItemGroup>
+
+  <ItemGroup Condition=" '$(TargetFrameworkIdentifier)' == '.NETCoreApp' and $([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), '6.0')) ">
+    <SdkSupportedTargetPlatformIdentifier Include="android" DisplayName="Android" />
+  </ItemGroup>
+</Project>

src/Xamarin.Android.Build.Tasks/Microsoft.NET.Sdk.Android/WorkloadManifest.targets

@@ -233,12 +233,12 @@ public void DotNetNew ([Values ("android", "androidlib", "android-bindinglib")]
 			new object[] {
 				"net6.0",
 				"android",
-				XABuildConfig.AndroidDefaultTargetDotnetApiLevel,
+				31,
 			},
 			new object[] {
 				"net6.0",
-				$"android{XABuildConfig.AndroidDefaultTargetDotnetApiLevel}",
-				XABuildConfig.AndroidDefaultTargetDotnetApiLevel,
+				"android31",
+				31,
 			},
 			new object[] {
 				"net7.0",

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/XASdkTests.cs

@@ -108,10 +108,26 @@ public static string DotNetAndroidSdkDirectory {
 					IsWindows ? "Microsoft.Android.Sdk.Windows" :
 					"Microsoft.Android.Sdk.Linux";
 
-				return _dotNetAndroidSdkDirectory = Directory.GetDirectories (Path.Combine (AndroidSdkResolver.GetDotNetPreviewPath (), "packs", sdkName)).LastOrDefault ();
+				var directories = from d in Directory.GetDirectories (Path.Combine (AndroidSdkResolver.GetDotNetPreviewPath (), "packs", sdkName))
+								  let version = ParseVersion (d)
+								  orderby version descending
+								  select d;
+				return _dotNetAndroidSdkDirectory = directories.FirstOrDefault ();
 			}
 		}
 
+		static Version ParseVersion (string path)
+		{
+			var folderName = Path.GetFileName (path);
+			var index = folderName.IndexOf ('-');
+			if (index != -1) {
+				folderName = folderName.Substring (0, index);
+			}
+			if (Version.TryParse (folderName, out var v))
+				return v;
+			return new Version (0, 0);
+		}
+
 		public static string DotNetAndroidSdkToolsDirectory {
 			get {
 				return Path.Combine (DotNetAndroidSdkDirectory, "tools");

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.ProjectTools/Common/TestEnvironment.cs

@@ -23,32 +23,43 @@ public class XASdkDeployTests : DeviceTest
 				/* isRelease */      false,
 				/* xamarinForms */   false,
 				/* publishTrimmed */ default (bool?),
+				/* targetFramework*/ "net7.0-android",
 			},
 			new object[] {
 				/* isRelease */      true,
 				/* xamarinForms */   false,
 				/* publishTrimmed */ default (bool?),
+				/* targetFramework*/ "net7.0-android",
 			},
 			new object[] {
 				/* isRelease */      false,
 				/* xamarinForms */   true,
 				/* publishTrimmed */ default (bool?),
+				/* targetFramework*/ "net7.0-android",
 			},
 			new object[] {
 				/* isRelease */      true,
 				/* xamarinForms */   true,
 				/* publishTrimmed */ default (bool?),
+				/* targetFramework*/ "net7.0-android",
 			},
 			new object[] {
 				/* isRelease */      true,
 				/* xamarinForms */   false,
 				/* publishTrimmed */ false,
+				/* targetFramework*/ "net7.0-android",
+			},
+			new object[] {
+				/* isRelease */      true,
+				/* xamarinForms */   true,
+				/* publishTrimmed */ true,
+				/* targetFramework*/ "net6.0-android",
 			},
 		};
 
 		[Test]
 		[TestCaseSource (nameof (DotNetInstallAndRunSource))]
-		public void DotNetInstallAndRun (bool isRelease, bool xamarinForms, bool? publishTrimmed)
+		public void DotNetInstallAndRun (bool isRelease, bool xamarinForms, bool? publishTrimmed, string targetFramework)
 		{
 			AssertHasDevices ();
 
@@ -62,6 +73,7 @@ public void DotNetInstallAndRun (bool isRelease, bool xamarinForms, bool? publis
 					IsRelease = isRelease
 				};
 			}
+			proj.TargetFramework = targetFramework;
 			if (publishTrimmed != null) {
 				proj.SetProperty (KnownProperties.PublishTrimmed, publishTrimmed.ToString ());
 			}
@@ -137,12 +149,13 @@ public void TypeAndMemberRemapping ([Values (false, true)] bool isRelease)
 
 		[Test]
 		[Category ("Debugger"), Category ("Node-4")]
-		public void DotNetDebug ()
+		public void DotNetDebug ([Values("net6.0-android", "net7.0-android")] string targetFramework)
 		{
 			AssertCommercialBuild ();
 			AssertHasDevices ();
 
 			var proj = new XASdkProject ();
+			proj.TargetFramework = targetFramework;
 			proj.SetRuntimeIdentifier (DeviceAbi);
 			string runtimeId = proj.GetProperty (KnownProperties.RuntimeIdentifier);