[One .NET] add $(AndroidGenerateResourceDesigner) property (#6224)

Fixes: #6198

When migrating Xamarin.Android binding projects to .NET 6, one
difference is that `Resource.designer.cs` will be generated by .NET 6
class libraries.

This can result in build failures, e.g.:

	error CS0101: The namespace 'MyBinding' already contains a definition for 'Resource'

There is not currently a way to turn this off; if you try:

	dotnet build -p:AndroidUseIntermediateDesignerFile=false

Then `Resources\Resource.designer.cs` will be generated instead.
There is no way to prevent this behavior, because
`$(AndroidResgenFile)` defaults to this value.

To solve cases where you *don't* want `Resource.designer.cs` at all:

 1. Remove the `$(AndroidResgenFile)` default value.

 2. Add a new `$(AndroidGenerateResourceDesigner)` MSBuild property,
    that seems like it will be a better name for .NET 6.
    `$(AndroidGenerateResourceDesigner)` defaults to True.

 3. `$(AndroidUseIntermediateDesignerFile)` is based on
    `$(AndroidGenerateResourceDesigner)`.

This way, if a Xamarin.Android binding project is migrated to .NET 6,
the binding project can set `$(AndroidGenerateResourceDesigner)`=False
to prevent `Resource.designer.cs` from being generated, which may
prevent build failures.

I added a test and docs for the new property.

Author: jonathanpeppers

Documentation/guides/OneDotNetBindingProjects.md

@@ -217,5 +217,36 @@ As the default for .NET 6 is `disable`, the same applies for Xamarin Android pro
 
 Use `enable` as shown above to enable NRT support.
 
-
 [11-0-release-notes]: https://docs.microsoft.com/en-us/xamarin/android/release-notes/11/11.0
+
+### `Resource.designer.cs`
+
+In Xamarin.Android, Java binding projects did not support generating a `Resource.designer.cs` file.
+Since binding projects are just class libraries in .NET 6, this file will be generated. This could
+be a breaking change when migrating existing projects.
+
+One example of a failure from this change, is if your binding generates a class named `Resource`
+in the root namespace:
+
+```
+error CS0101: The namespace 'MyBinding' already contains a definition for 'Resource'
+```
+
+Or in the case of AndroidX, we have project files with `-` in the name such as
+`androidx.window/window-extensions.csproj`. This results in the root namespace `window-extensions`
+and invalid C# in `Resource.designer.cs`:
+
+```
+error CS0116: A namespace cannot directly contain members such as fields, methods or statements
+error CS1514: { expected 
+error CS1022: Type or namespace definition, or end-of-file expected
+```
+
+To disable `Resource.designer.cs` generation, set `$(AndroidGenerateResourceDesigner)` to `false`
+in your `.csproj`:
+
+```xml
+<PropertyGroup>
+  <AndroidGenerateResourceDesigner>false</AndroidGenerateResourceDesigner>
+</PropertyGroup>
+```

Documentation/guides/building-apps/build-properties.md

@@ -569,6 +569,12 @@ Enables generation of [layout code-behind](https://github.com/xamarin/xamarin-an
 if set to `true` or disables it completely if set to `false`. The
 default value is `false`.
 
+## AndroidGenerateResourceDesigner
+
+Defaults to `true`. When set to `false`, disables the generation of `Resource.designer.cs`.
+
+Added in .NET 6 RC 1. Not supported in Xamarin.Android.
+
 ## AndroidHttpClientHandlerType
 
 Controls the default

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.DefaultProperties.targets

@@ -7,11 +7,11 @@
     <MonoAndroidResourcePrefix Condition=" '$(MonoAndroidResourcePrefix)' == '' ">Resources</MonoAndroidResourcePrefix>
     <MonoAndroidAssetsPrefix Condition=" '$(MonoAndroidAssetsPrefix)' == '' ">Assets</MonoAndroidAssetsPrefix>
     <AndroidResgenClass Condition=" '$(AndroidResgenClass)' == '' ">Resource</AndroidResgenClass>
-    <AndroidResgenFile Condition=" '$(AndroidResgenFile)' == '' ">$(MonoAndroidResourcePrefix)\$(_AndroidResourceDesigner)</AndroidResgenFile>
     <AndroidEnableSGenConcurrent Condition=" '$(AndroidEnableSGenConcurrent)' == '' ">true</AndroidEnableSGenConcurrent>
     <AndroidHttpClientHandlerType Condition=" '$(AndroidHttpClientHandlerType)' == '' and '$(UsingAndroidNETSdk)' == 'true' ">Xamarin.Android.Net.AndroidMessageHandler</AndroidHttpClientHandlerType>
     <AndroidHttpClientHandlerType Condition=" '$(AndroidHttpClientHandlerType)' == '' and '$(UsingAndroidNETSdk)' != 'true' ">Xamarin.Android.Net.AndroidClientHandler</AndroidHttpClientHandlerType>
-    <AndroidUseIntermediateDesignerFile Condition=" '$(AndroidUseIntermediateDesignerFile)' == '' ">true</AndroidUseIntermediateDesignerFile>
+    <AndroidGenerateResourceDesigner Condition=" '$(AndroidGenerateResourceDesigner)' == '' ">true</AndroidGenerateResourceDesigner>
+    <AndroidUseIntermediateDesignerFile Condition=" '$(AndroidUseIntermediateDesignerFile)' == '' ">$(AndroidGenerateResourceDesigner)</AndroidUseIntermediateDesignerFile>
     <GenerateDependencyFile Condition=" '$(GenerateDependencyFile)' == '' ">false</GenerateDependencyFile>
     <CopyLocalLockFileAssemblies Condition=" '$(CopyLocalLockFileAssemblies)' == '' ">false</CopyLocalLockFileAssemblies>
     <ComputeNETCoreBuildOutputFiles Condition=" '$(ComputeNETCoreBuildOutputFiles)' == '' ">false</ComputeNETCoreBuildOutputFiles>

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

@@ -286,6 +286,37 @@ public void DotNetLibraryAarChanges ()
 			}
 		}
 
+		[Test]
+		public void GenerateResourceDesigner_false()
+		{
+			var proj = new XASdkProject (outputType: "Library") {
+				Sources = {
+					new AndroidItem.AndroidResource (() => "Resources\\drawable\\foo.png") {
+						BinaryContent = () => XamarinAndroidCommonProject.icon_binary_mdpi,
+					},
+				}
+			};
+			// Turn off Resource.designer.cs and remove usage of it
+			proj.SetProperty ("AndroidGenerateResourceDesigner", "false");
+			proj.MainActivity = proj.DefaultMainActivity
+				.Replace ("Resource.Layout.Main", "0")
+				.Replace ("Resource.Id.myButton", "0");
+
+			var dotnet = CreateDotNetBuilder (proj);
+			Assert.IsTrue (dotnet.Build (), "build should succeed");
+
+			var intermediate = Path.Combine (FullProjectDirectory, proj.IntermediateOutputPath);
+			var resource_designer_cs = Path.Combine (intermediate, "Resource.designer.cs");
+			FileAssert.DoesNotExist (resource_designer_cs);
+
+			var assemblyPath = Path.Combine (FullProjectDirectory, proj.OutputPath, $"{proj.ProjectName}.dll");
+			FileAssert.Exists (assemblyPath);
+			using var assembly = AssemblyDefinition.ReadAssembly (assemblyPath);
+			var typeName = $"{proj.ProjectName}.Resource";
+			var type = assembly.MainModule.GetType (typeName);
+			Assert.IsNull (type, $"{assemblyPath} should *not* contain {typeName}");
+		}
+
 		[Test]
 		[Category ("SmokeTests")]
 		public void DotNetBuildBinding ()

tests/CodeBehind/BuildTests/CodeBehindBuildTests.NET.csproj

@@ -7,6 +7,7 @@
     <_ApkDebugKeyStore>debug.keystore</_ApkDebugKeyStore>
     <EnableDefaultItems>false</EnableDefaultItems>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
+    <AndroidResgenFile>Resources\Resource.designer.cs</AndroidResgenFile>
     <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
     <AppendRuntimeIdentifierToOutputPath>false</AppendRuntimeIdentifierToOutputPath>
     <AppendTargetFrameworkToIntermediateOutputPath>false</AppendTargetFrameworkToIntermediateOutputPath>

tests/Mono.Android-Tests/Runtime-Microsoft.Android.Sdk/Mono.Android.NET-Tests.csproj

@@ -33,7 +33,6 @@
 
   <ItemGroup>
     <Compile Remove="..\Resources\Resource.designer.cs" />
-    <Compile Include="Resources\Resource.designer.cs" />
     <Compile Include="System\AppContextTests.cs" />
     <!-- Mono.Data.Sqlite is not supported in .NET 6 -->
     <Compile Remove="..\Mono.Data.Sqlite\SqliteTests.cs" />