[Xamarin.Android.Build.Tasks] allow multiple r-classes.jar files (dot…

…net#5691)

Fixes: dotnet#5627

In some cases, Android Studio projects can produce `.aar` files that
contain:

	libs/r-classes.jar

Reviewing the contents of one of these `r-classes.jar` files:

	$ jar tf libs/r-classes.jar
	com/test/R.class

It appears Android Studio is potentially moving any `R.java` files
into this new `r-classes.jar` file.

If you have two `.aar` files that contain a `r-classes.jar` in a
Xamarin.Android application, you would currently run into the error:

	JAR library references with identical file names but different contents were found: r-classes.jar.
	Please remove any conflicting libraries from EmbeddedJar, InputJar and AndroidJavaLibrary.

Make the `<CheckDuplicateJavaLibraries/>` MSBuild task
ignore this issue for `r-classes.jar`, as it does for `classes.jar`.

I can't find any good links to explain this new file, or why it exists.

I added a test for this scenario.

src/Xamarin.Android.Build.Tasks/Tasks/CheckDuplicateJavaLibraries.cs

@@ -9,6 +9,11 @@ namespace Xamarin.Android.Tasks
 {
 	public class CheckDuplicateJavaLibraries : AndroidTask
 	{
+		readonly static string [] ExcludedFiles = new [] {
+			"classes.jar",
+			"r-classes.jar",
+		};
+
 		public override string TaskPrefix => "CDJ";
 
 		public ITaskItem [] JavaSourceFiles { get; set; }
@@ -26,7 +31,7 @@ public override bool RunTask ()
 
 			// Remove duplicate identical jars by name, size and content, and reject any jars that conflicts by name (i.e. different content).
 			var jars = MonoAndroidHelper.DistinctFilesByContent (jarFilePaths).ToArray ();
-			var dups = MonoAndroidHelper.GetDuplicateFileNames (jars, new string [] {"classes.jar"});
+			var dups = MonoAndroidHelper.GetDuplicateFileNames (jars, ExcludedFiles);
 			if (dups.Any ()) {
 				Log.LogCodedError ("XA1014", Properties.Resources.XA1014, String.Join (", ", dups.ToArray ()));
 				return false;

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

@@ -650,5 +650,42 @@ public void LibraryProjectZipWithLint ()
 					"`lint.jar` should not be extracted!");
 			}
 		}
+
+		/// <summary>
+		/// Tests two .aar files with r-classes.jar
+		/// </summary>
+		[Test]
+		public void AarWithRClassesJar ()
+		{
+			var path = Path.Combine ("temp", TestName);
+			var lib1 = new XamarinAndroidBindingProject {
+				ProjectName = "Library1",
+				AndroidClassParser = "class-parse",
+				Jars = {
+					new AndroidItem.LibraryProjectZip ("Library1.aar") {
+						BinaryContent = () => ResourceData.Library1Aar
+					}
+				},
+			};
+			var lib2 = new XamarinAndroidBindingProject {
+				ProjectName = "Library2",
+				AndroidClassParser = "class-parse",
+				Jars = {
+					new AndroidItem.LibraryProjectZip ("Library2.aar") {
+						BinaryContent = () => ResourceData.Library2Aar
+					}
+				},
+			};
+			var app = new XamarinAndroidApplicationProject ();
+			app.AddReference (lib1);
+			app.AddReference (lib2);
+			using (var lib1Builder = CreateDllBuilder (Path.Combine (path, lib1.ProjectName)))
+			using (var lib2Builder = CreateDllBuilder (Path.Combine (path, lib2.ProjectName)))
+			using (var appBuilder = CreateApkBuilder (Path.Combine (path, app.ProjectName))) {
+				Assert.IsTrue (lib1Builder.Build (lib1), "Library1 build should have succeeded.");
+				Assert.IsTrue (lib2Builder.Build (lib2), "Library2 build should have succeeded.");
+				Assert.IsTrue (appBuilder.Build (app), "App build should have succeeded.");
+			}
+		}
 	}
 }

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Utilities/ResourceData.cs

@@ -12,14 +12,18 @@ static class ResourceData
 		static Lazy<byte[]> javaSourceJarTestJar        = new Lazy<byte[]>(() => GetResourceData ("javasourcejartest.jar"));
 		static Lazy<byte[]> javaSourceJarTestSourcesJar = new Lazy<byte[]>(() => GetResourceData ("javasourcejartest-sources.jar"));
 		static Lazy<byte[]> javaSourceJarTestJavadocJar = new Lazy<byte[]>(() => GetResourceData ("javasourcejartest-javadoc.jar"));
+		static Lazy<byte []> library1Aar = new Lazy<byte []> (() => GetResourceData ("library1.aar"));
+		static Lazy<byte []> library2Aar = new Lazy<byte []> (() => GetResourceData ("library2.aar"));
 
 		public  static  byte[]  JavaSourceJarTestJar            => javaSourceJarTestJar.Value;
 		public  static  byte[]  JavaSourceJarTestSourcesJar     => javaSourceJarTestSourcesJar.Value;
 		public  static  byte[]  JavaSourceJarTestJavadocJar     => javaSourceJarTestJavadocJar.Value;
+		public  static  byte [] Library1Aar => library1Aar.Value;
+		public  static  byte [] Library2Aar => library2Aar.Value;
 
 		static byte[] GetResourceData (string name)
 		{
-			using var s = typeof (InlineData).Assembly.GetManifestResourceStream (name);
+			using var s = typeof (ResourceData).Assembly.GetManifestResourceStream (name);
 			using var m = new MemoryStream (checked ((int) s.Length));
 			s.CopyTo (m);
 			return m.ToArray ();

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Xamarin.Android.Build.Tests.csproj

@@ -43,14 +43,8 @@
   </ItemGroup>
 
   <ItemGroup>
-    <EmbeddedResource Include="Resources\javasourcejartest.jar">
-      <LogicalName>javasourcejartest.jar</LogicalName>
-    </EmbeddedResource>
-    <EmbeddedResource Include="Resources\javasourcejartest-sources.jar">
-      <LogicalName>javasourcejartest-sources.jar</LogicalName>
-    </EmbeddedResource>
-    <EmbeddedResource Include="Resources\javasourcejartest-javadoc.jar">
-      <LogicalName>javasourcejartest-javadoc.jar</LogicalName>
+    <EmbeddedResource Include="Resources\*">
+      <LogicalName>%(FileName)%(Extension)</LogicalName>
     </EmbeddedResource>
   </ItemGroup>