[Xamarin.Android.Build.Tasks] Add support for Proguard mapping.txt file

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

@@ -806,6 +806,17 @@ with build environments that have FIPS compliance enforced.
 
 Added in Xamarin.Android 10.1.
 
+## AndroidProguardMappingFile
+
+Specifies the `-printmapping` proguard rule for `r8`. This will
+mean the `mapping.txt` file will be produced in the `$(OutputPath)`
+folder. This file can then be used when uploading packages to the
+Google Play Store.
+
+Default value is `$(OutputPath)mapping.txt`
+
+Added in Xamarin.Android 11.2
+
 ## AndroidR8IgnoreWarnings
 
 Specifies

Documentation/release-notes/5304.md

@@ -0,0 +1,9 @@
+### Build and deployment performance
+
+  * [GitHub PR 5304](https://github.com/xamarin/xamarin-android/pull/5304):
+    Add support for producing a proguard `mapping.txt` file to the
+    build system. This file can be used by users to remove this warning
+
+        "This App Bundle contains Java/Kotlin code, which might be obfuscated."
+
+    when uploading packages to the Google Play Store.

src/Xamarin.Android.Build.Tasks/Resources/proguard_xamarin.cfg

@@ -2,6 +2,10 @@
 
 -dontobfuscate
 
+# required for publishing proguard mapping file
+-keepattributes SourceFile
+-keepattributes LineNumberTable
+
 -keep class android.support.multidex.MultiDexApplication { <init>(); }
 -keep class com.xamarin.java_interop.** { *; <init>(); }
 -keep class mono.MonoRuntimeProvider* { *; <init>(...); }

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

@@ -48,14 +48,15 @@ public class Proguard : AndroidToolTask
 		public string ProguardGeneratedReferenceConfiguration { get; set; }
 		public string ProguardGeneratedApplicationConfiguration { get; set; }
 		public string ProguardCommonXamarinConfiguration { get; set; }
+		public string ProguardMappingFileOutput { get; set; }
 
 		[Required]
 		public string [] ProguardConfigurationFiles { get; set; }
 
 		public ITaskItem[] JavaLibrariesToEmbed { get; set; }
-		
+
 		public ITaskItem[] JavaLibrariesToReference { get; set; }
-		
+
 		public bool UseProguard { get; set; }
 
 		public string JavaOptions { get; set; }
@@ -92,11 +93,11 @@ protected override string GenerateCommandLineCommands ()
 				// Add the JavaOptions if they are not null
 				// These could be any of the additional options
 				if (!string.IsNullOrEmpty (JavaOptions)) {
-					cmd.AppendSwitch (JavaOptions);		
+					cmd.AppendSwitch (JavaOptions);
 				}
 
 				// Add the specific -XmxN to override the default heap size for the JVM
-				// N can be in the form of Nm or NGB (e.g 100m or 1GB ) 
+				// N can be in the form of Nm or NGB (e.g 100m or 1GB )
 				cmd.AppendSwitchIfNotNull ("-Xmx", JavaMaximumHeapSize);
 
 				cmd.AppendSwitchIfNotNull ("-jar ", Path.Combine (ProguardJarPath));
@@ -118,9 +119,12 @@ protected override string GenerateCommandLineCommands ()
 					}
 
 			if (!string.IsNullOrWhiteSpace (ProguardCommonXamarinConfiguration))
-				using (var xamcfg = File.Create (ProguardCommonXamarinConfiguration))
-					GetType ().Assembly.GetManifestResourceStream ("proguard_xamarin.cfg").CopyTo (xamcfg);
-
+				using (var xamcfg = File.CreateText (ProguardCommonXamarinConfiguration)) {
+					GetType ().Assembly.GetManifestResourceStream ("proguard_xamarin.cfg").CopyTo (xamcfg.BaseStream);
+					if (!string.IsNullOrEmpty (ProguardMappingFileOutput))
+						xamcfg.WriteLine ($"-printmapping {Path.GetFullPath (ProguardMappingFileOutput)}");
+				}
+
 			var enclosingChar = OS.IsWindows ? "\"" : string.Empty;
 
 			foreach (var file in ProguardConfigurationFiles) {

src/Xamarin.Android.Build.Tasks/Tasks/R8.cs

@@ -29,6 +29,7 @@ public class R8 : D8
 		public string ProguardGeneratedReferenceConfiguration { get; set; }
 		public string ProguardGeneratedApplicationConfiguration { get; set; }
 		public string ProguardCommonXamarinConfiguration { get; set; }
+		public string ProguardMappingFileOutput { get; set; }
 		public string [] ProguardConfigurationFiles { get; set; }
 
 		protected override string MainClass => "com.android.tools.r8.R8";
@@ -99,6 +100,8 @@ protected override CommandLineBuilder GetCommandLineBuilder ()
 						if (IgnoreWarnings) {
 							xamcfg.WriteLine ("-ignorewarnings");
 						}
+						if (!string.IsNullOrEmpty (ProguardMappingFileOutput))
+							xamcfg.WriteLine ($"-printmapping {Path.GetFullPath (ProguardMappingFileOutput)}");
 					}
 				}
 			} else {
@@ -115,6 +118,8 @@ protected override CommandLineBuilder GetCommandLineBuilder ()
 				if (IgnoreWarnings) {
 					lines.Add ("-ignorewarnings");
 				}
+				if (!string.IsNullOrEmpty (ProguardMappingFileOutput))
+					lines.Add ($"-printmapping {Path.GetFullPath (ProguardMappingFileOutput)}");
 				File.WriteAllLines (temp, lines);
 				tempFiles.Add (temp);
 				cmd.AppendSwitchIfNotNull ("--pg-conf ", temp);
@@ -131,5 +136,5 @@ protected override CommandLineBuilder GetCommandLineBuilder ()
 			return cmd;
 		}
 	}
-	
+
 }

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

@@ -48,6 +48,21 @@ public void CheckManagedSymbolsArchive (bool isRelease, bool monoSymbolArchive,
 			}
 		}
 
+		[Test]
+		public void CheckProguardMappingFileExists ()
+		{
+			var proj = new XamarinAndroidApplicationProject {
+				IsRelease = true,
+			};
+			proj.SetProperty (proj.ReleaseProperties, KnownProperties.AndroidDexTool, "d8");
+			proj.SetProperty (proj.ReleaseProperties, KnownProperties.AndroidLinkTool, "r8");
+			using (var b = CreateApkBuilder ()) {
+				Assert.IsTrue (b.Build (proj), "build should have succeeded.");
+				string mappingFile = Path.Combine (Root, b.ProjectDirectory, proj.OutputPath, "mapping.txt");
+				FileAssert.Exists (mappingFile, $"'{mappingFile}' should have been generated.");
+			}
+		}
+
 		[Test]
 		public void CheckIncludedAssemblies ()
 		{

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -275,6 +275,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 	<AndroidLinkTool       Condition=" '$(AndroidLinkTool)' == '' And '$(AndroidEnableProguard)' == 'True' ">proguard</AndroidLinkTool>
 	<AndroidLinkTool       Condition=" '$(AndroidLinkTool)' == 'proguard' And '$(AndroidEnableDesugar)' == 'True' ">r8</AndroidLinkTool>
 	<AndroidEnableProguard Condition=" '$(AndroidLinkTool)' != '' ">True</AndroidEnableProguard>
+  <AndroidProguardMappingFile Condition=" '$(AndroidProguardMappingFile)' == '' ">$(OutputPath)mapping.txt</AndroidProguardMappingFile>
 	<AndroidEnableDesugar  Condition=" '$(AndroidEnableDesugar)' == '' And ('$(AndroidDexTool)' == 'd8' Or '$(AndroidLinkTool)' == 'r8') ">True</AndroidEnableDesugar>
 	<AndroidEnableDesugar  Condition=" '$(AndroidEnableDesugar)' == '' ">False</AndroidEnableDesugar>
 	<AndroidR8IgnoreWarnings    Condition=" '$(AndroidR8IgnoreWarnings)' == '' ">True</AndroidR8IgnoreWarnings>

src/Xamarin.Android.Build.Tasks/Xamarin.Android.D8.targets

@@ -67,6 +67,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
         ProguardCommonXamarinConfiguration="$(IntermediateOutputPath)proguard\proguard_xamarin.cfg"
         ProguardGeneratedReferenceConfiguration="$(_ProguardProjectConfiguration)"
         ProguardGeneratedApplicationConfiguration="$(IntermediateOutputPath)proguard\proguard_project_primary.cfg"
+        ProguardMappingFileOutput="$(AndroidProguardMappingFile)"
         ProguardConfigurationFiles="@(_ProguardConfiguration)"
         EnableShrinking="$(_R8EnableShrinking)"
         EnableMultiDex="$(AndroidEnableMultiDex)"
@@ -96,6 +97,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
     <Touch Files="$(_AndroidStampDirectory)_CompileToDalvik.stamp" AlwaysCreate="true" />
     <ItemGroup>
       <FileWrites Include="$(_AndroidIntermediateDexOutputDirectory)*.dex" />
+      <FileWrites Include="$(AndroidProguardMappingFile)" />
     </ItemGroup>
 
   </Target>

src/Xamarin.Android.Build.Tasks/Xamarin.Android.DX.targets

@@ -26,7 +26,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
     <ItemGroup>
       <_JarsToProguard Include="@(_JavaLibrariesToCompile)" />
     </ItemGroup>
-    
+
     <MakeDir Directories="$(IntermediateOutputPath)proguard" />
 
     <Proguard
@@ -42,6 +42,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
         ProguardCommonXamarinConfiguration="$(IntermediateOutputPath)proguard\proguard_xamarin.cfg"
         ProguardGeneratedReferenceConfiguration="$(_ProguardProjectConfiguration)"
         ProguardGeneratedApplicationConfiguration="$(IntermediateOutputPath)proguard\proguard_project_primary.cfg"
+        ProguardMappingFileOutput="$(AndroidProguardMappingFile)"
         ProguardConfigurationFiles="@(_ProguardConfiguration)"
         JavaLibrariesToEmbed="@(_JarsToProguard);@(_InstantRunJavaReference)"
         JavaLibrariesToReference="@(AndroidExternalJavaLibrary)"
@@ -79,7 +80,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
     <Delete Files="@(_DexesToDelete)" />
 
     <!-- Compile java code to dalvik -->
-    <CompileToDalvik 
+    <CompileToDalvik
         DxJarPath="$(DxJarPath)"
         DxExtraArguments="$(DxExtraArguments)"
         JavaToolPath="$(JavaToolPath)"
@@ -98,6 +99,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
     <Touch Files="$(_AndroidStampDirectory)_CompileToDalvik.stamp" AlwaysCreate="true" />
     <ItemGroup>
       <FileWrites Include="$(_AndroidIntermediateDexOutputDirectory)*.dex" />
+      <FileWrites Include="$(AndroidProguardMappingFile)" />
     </ItemGroup>
 
   </Target>