move native libraries targeting mobile to a separate Grpc.Core.Xamarin package

src/csharp/Grpc.Core.Xamarin/.gitignore

@@ -0,0 +1,2 @@
+bin
+obj

src/csharp/Grpc.Core.Xamarin/Grpc.Core.Xamarin.csproj

@@ -0,0 +1,61 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <Import Project="..\Grpc.Core\Common.csproj.include" />
+
+  <PropertyGroup>
+    <Authors>The gRPC Authors</Authors>
+    <Copyright>Copyright 2015 The gRPC Authors</Copyright>
+    <Description>Xamarin support for gRPC C#. Note that the gRPC C# support for the Xamarin platform is considered experimental.
+    This package contains the native grpc_csharp_ext libraries that are needed to run gRPC C# on mobile platforms (Android, iOS).
+    WARNING: Versions of Grpc.Core.Xamarin and Grpc.Core dependencies being used in your project must always match exactly, otherwise
+    things will be badly broken.</Description>
+    <PackageIconUrl>https://github.com/grpc/grpc.github.io/raw/master/img/grpc_square_reverse_4x.png</PackageIconUrl>
+    <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
+    <PackageProjectUrl>https://github.com/grpc/grpc</PackageProjectUrl>
+    <PackageTags>gRPC RPC HTTP/2</PackageTags>
+    <VersionPrefix>$(GrpcCsharpVersion)</VersionPrefix>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <TargetFrameworks>net45;netstandard1.5;netstandard2.0</TargetFrameworks>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+
+  <Import Project="..\Grpc.Core\SourceLink.csproj.include" />
+
+  <ItemGroup>
+    <Content Include="..\nativelibs\csharp_ext_linux_android_armeabi-v7a\libgrpc_csharp_ext.so">
+      <PackagePath>native/android/armeabi-v7a/libgrpc_csharp_ext.so</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="..\nativelibs\csharp_ext_linux_android_arm64-v8a\libgrpc_csharp_ext.so">
+      <PackagePath>native/android/arm64-v8a/libgrpc_csharp_ext.so</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="..\nativelibs\csharp_ext_linux_android_x86\libgrpc_csharp_ext.so">
+      <PackagePath>native/android/x86/libgrpc_csharp_ext.so</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="..\nativelibs\csharp_ext_macos_ios\libgrpc_csharp_ext.a">
+      <PackagePath>native/ios/universal/libgrpc_csharp_ext.a</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="..\nativelibs\csharp_ext_macos_ios\libgrpc.a">
+      <PackagePath>native/ios/universal/libgrpc.a</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="build\MonoAndroid10\Grpc.Core.Xamarin.targets">
+      <PackagePath>build/MonoAndroid10/</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+    <Content Include="build\Xamarin.iOS10\Grpc.Core.Xamarin.targets">
+      <PackagePath>build/Xamarin.iOS10/</PackagePath>
+      <Pack>true</Pack>
+    </Content>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="../Grpc.Core/Grpc.Core.csproj" />
+  </ItemGroup>
+</Project>

src/csharp/Grpc.Core.Xamarin/Internal.cs

@@ -0,0 +1,24 @@
+#region Copyright notice and license
+// Copyright 2020 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#endregion
+
+namespace Grpc.Core
+{
+
+    // Generate an empty assembly
+    internal static class UnusedClass
+    {
+    }
+}

src/csharp/Grpc.Core/Grpc.Core.csproj

@@ -51,38 +51,10 @@
       <PackagePath>runtimes/win/native/grpc_csharp_ext.x86.dll</PackagePath>
       <Pack>true</Pack>
     </Content>
-    <Content Include="..\nativelibs\csharp_ext_linux_android_armeabi-v7a\libgrpc_csharp_ext.so">
-      <PackagePath>native/android/armeabi-v7a/libgrpc_csharp_ext.so</PackagePath>
-      <Pack>true</Pack>
-    </Content>
-    <Content Include="..\nativelibs\csharp_ext_linux_android_arm64-v8a\libgrpc_csharp_ext.so">
-      <PackagePath>native/android/arm64-v8a/libgrpc_csharp_ext.so</PackagePath>
-      <Pack>true</Pack>
-    </Content>
-    <Content Include="..\nativelibs\csharp_ext_linux_android_x86\libgrpc_csharp_ext.so">
-      <PackagePath>native/android/x86/libgrpc_csharp_ext.so</PackagePath>
-      <Pack>true</Pack>
-    </Content>
-    <Content Include="..\nativelibs\csharp_ext_macos_ios\libgrpc_csharp_ext.a">
-      <PackagePath>native/ios/universal/libgrpc_csharp_ext.a</PackagePath>
-      <Pack>true</Pack>
-    </Content>
-    <Content Include="..\nativelibs\csharp_ext_macos_ios\libgrpc.a">
-      <PackagePath>native/ios/universal/libgrpc.a</PackagePath>
-      <Pack>true</Pack>
-    </Content>
     <Content Include="build\net45\Grpc.Core.targets">
       <PackagePath>build/net45/</PackagePath>
       <Pack>true</Pack>
     </Content>
-    <Content Include="build\MonoAndroid10\Grpc.Core.targets">
-      <PackagePath>build/MonoAndroid10/</PackagePath>
-      <Pack>true</Pack>
-    </Content>
-    <Content Include="build\Xamarin.iOS10\Grpc.Core.targets">
-      <PackagePath>build/Xamarin.iOS10/</PackagePath>
-      <Pack>true</Pack>
-    </Content>
   </ItemGroup>
 
   <ItemGroup>

src/csharp/Grpc.sln

@@ -47,6 +47,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Grpc.Tools.Tests", "Grpc.To
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Grpc.IntegrationTesting.XdsClient", "Grpc.IntegrationTesting.XdsClient\Grpc.IntegrationTesting.XdsClient.csproj", "{7306313A-4853-4CFF-B913-0FCB1A497449}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Grpc.Core.Xamarin", "Grpc.Core.Xamarin\Grpc.Core.Xamarin.csproj", "{1DCB698B-1383-4297-975A-EC8383295141}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -141,6 +143,10 @@ Global
 		{7306313A-4853-4CFF-B913-0FCB1A497449}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7306313A-4853-4CFF-B913-0FCB1A497449}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{7306313A-4853-4CFF-B913-0FCB1A497449}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1DCB698B-1383-4297-975A-EC8383295141}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1DCB698B-1383-4297-975A-EC8383295141}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1DCB698B-1383-4297-975A-EC8383295141}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1DCB698B-1383-4297-975A-EC8383295141}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

src/csharp/build_nuget.sh

@@ -47,6 +47,7 @@ dotnet pack --configuration Release Grpc.Tools --output ../../../artifacts
 # rem build auxiliary packages
 dotnet pack --configuration Release Grpc --output ../../../artifacts
 dotnet pack --configuration Release Grpc.Core.NativeDebug --output ../../../artifacts
+dotnet pack --configuration Release Grpc.Core.Xamarin --output ../../../artifacts
 
 # Create a zipfile with all the nugets we just created
 cd ../../artifacts

src/csharp/experimental/README.md

@@ -6,6 +6,12 @@ platforms that are not yet fully supported.
 gRPC C# now has experimental support for Xamarin.
 See [HelloworldXamarin](/examples/csharp/HelloworldXamarin) for an example how to use it.
 
+Starting from gRPC C# 2.34.x: in addition to the regular `Grpc.Core` dependency, you will also
+need to add `Grpc.Core.Xamarin` dependency to your project (which has the mobile-specific builds of c# native extension library).
+The `Grpc.Core` and `Grpc.Core.Xamarin` package versions must always match exactly for things to work.
+Also note that the `Grpc.Core.Xamarin` needs to be added to your `*.Android` and `*.iOS` projects
+in order for the native library bindings to be registered correctly (see https://github.com/grpc/grpc/issues/16250).
+
 What's currently supported:
 
 Xamarin.Android