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[build] Pass class files directly to D8 and R8 #12438

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e2c5f69
[build] Pass class files directly to D8 and R8
simonrozsival Aug 19, 2026
6951a1c
[tests] Check loose javac class outputs
simonrozsival Aug 19, 2026
3d7d113
[build] Separate binding JAR creation from Javac
simonrozsival Aug 20, 2026
ceb8a43
[build] Avoid binding JARs in app builds
simonrozsival Aug 20, 2026
5815d1f
[tests] Exercise bound Java source in app builds
simonrozsival Aug 20, 2026
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4 changes: 2 additions & 2 deletions ...n.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Bindings.ClassParse.targets
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Expand Up @@ -31,7 +31,7 @@ This file is only used by binding projects.

<Target Name="_ExportJarToXml"
DependsOnTargets="_ExtractJavadocsFromJavaSourceJars;_ExportJarToXmlInputs"
Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);@(_AndroidMSBuildAllProjects)"
Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);@(_JavaBindingClassFile);@(_AndroidMSBuildAllProjects)"
Outputs="@(_ExportJarToXmlOutputs)">

<PropertyGroup>
Expand All @@ -50,7 +50,7 @@ This file is only used by binding projects.
</ItemGroup>
<ClassParse
OutputFile="$(ApiOutputFile).class-parse"
SourceJars="@(EmbeddedJar);@(InputJar)"
SourceJars="@(EmbeddedJar);@(InputJar);@(_JavaBindingClassFile)"
ReferenceOutputFile="$(ApiOutputFile).reference.class-parse"
ReferenceJars="@(EmbeddedReferenceJar);@(ReferenceJar)"
DocumentationPaths="@(_AndroidDocumentationPath)"
Expand Down
23 changes: 17 additions & 6 deletions src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Javac.targets
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Expand Up @@ -106,15 +106,14 @@ It is shared between "legacy" binding projects and .NET 7+ projects.
Inputs="@(_AndroidMSBuildAllProjects);$(_AndroidCompileBindingJavaFileList);$(MonoPlatformJarPath);@(_JavaBindingSource)"
Outputs="$(_AndroidCompileBindingJavaStampFile)">

<!-- remove existing <Javac /> outputs, since *.class files and classes.zip could contain old files -->
<!-- remove existing outputs, since *.class and *.jar files could contain old files -->
<RemoveDirFixed Directories="$(_AndroidIntermediateBindingJavaClassDirectory)" Condition="Exists('$(_AndroidIntermediateBindingJavaClassDirectory)')" />
<Delete Files="$(_AndroidIntermediateBindingClassesZip)" Condition="Exists('$(_AndroidIntermediateBindingClassesZip)')" />
<!-- Compile java code -->
<Javac
Condition=" '@(_JavaBindingSource->Count())' != '0' "
JavaPlatformJarPath="$(JavaPlatformJarPath)"
ClassesOutputDirectory="$(_AndroidIntermediateBindingJavaClassDirectory)"
ClassesZip="$(_AndroidIntermediateBindingClassesZip)"
StubSourceDirectory="$(_AndroidIntermediateBindingJavaSourceDirectory)"
JavaSourceFiles="@(_JavaBindingSource)"
ToolPath="$(JavacToolPath)"
Expand All @@ -126,6 +125,12 @@ It is shared between "legacy" binding projects and .NET 7+ projects.
IntermediateOutputPath="$(IntermediateOutputPath)"
AssemblyIdentityMapFile="$(_AndroidLibrayProjectAssemblyMapFile)"
/>
<ZipDirectory
Condition=" '$(AndroidApplication)' != 'true' or '$(AndroidClassParser)' == 'jar2xml' "
SourceDirectory="$(_AndroidIntermediateBindingJavaClassDirectory)"
DestinationFile="$(_AndroidIntermediateBindingClassesZip)"
Overwrite="true"
/>
<JavaSourceUtils
Condition=" '@(_JavaBindingSource->Count())' != '0' "
JavaSourceUtilsJar="$(AndroidJavaSourceUtilsJar)"
Expand All @@ -142,6 +147,14 @@ It is shared between "legacy" binding projects and .NET 7+ projects.
/>
<Touch Files="$(_AndroidCompileBindingJavaStampFile)" AlwaysCreate="true" />
<ItemGroup>
<_JavaBindingClassDirectory
Condition=" '$(AndroidApplication)' == 'true' and '$(AndroidClassParser)' != 'jar2xml' "
Include="$(_AndroidIntermediateBindingJavaClassDirectory)"
/>
<_JavaBindingClassFile
Condition=" '$(AndroidApplication)' == 'true' and '$(AndroidClassParser)' != 'jar2xml' "
Include="$(_AndroidIntermediateBindingJavaClassDirectory)**\*.class"
/>
<EmbeddedJar Include="$(_AndroidIntermediateBindingClassesZip)" Condition="Exists('$(_AndroidIntermediateBindingClassesZip)')" />
<AndroidJavaLibrary Include="$(_AndroidIntermediateBindingClassesZip)" Condition="Exists('$(_AndroidIntermediateBindingClassesZip)')" />
<FileWrites Include="$(_AndroidIntermediateBindingClassesZip)" Condition="Exists('$(_AndroidIntermediateBindingClassesZip)')" />
Expand All @@ -154,21 +167,19 @@ It is shared between "legacy" binding projects and .NET 7+ projects.
Inputs="@(_AndroidMSBuildAllProjects);$(_AndroidCompileJavaFileList);$(MonoPlatformJarPath);@(_JavaStubFiles);@(_JavaSource)"
Outputs="$(_AndroidCompileJavaStampFile)">

<!-- remove existing <Javac /> outputs, since *.class files and classes.zip could contain old files -->
<!-- remove existing <Javac /> outputs, since *.class files could contain old files -->

@jonathanpeppers jonathanpeppers Aug 19, 2026

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The <Javac/> task still has the ClassesZip property and code to create the classes.zip, can we remove that, too?

@simonrozsival simonrozsival Aug 20, 2026

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Done in 3d7d113. Javac no longer has a ClassesZip property or archive-writing code. _CompileBindingJava now creates its required binding JAR separately with MSBuild’s ZipDirectory task.

@simonrozsival simonrozsival Aug 20, 2026

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Follow-up in ceb8a43: class-parse app builds now avoid the binding JAR as well. Their bound .class files flow directly to class-parse, javac, and D8/R8. JAR creation remains only for library/AAR output and legacy jar2xml.

<RemoveDirFixed Directories="$(_AndroidIntermediateJavaClassDirectory)" />
<Delete Files="$(_AndroidIntermediateClassesZip)" />

<!-- Compile java code -->
<Javac
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JavaPlatformJarPath="$(JavaPlatformJarPath)"
ClassesOutputDirectory="$(_AndroidIntermediateJavaClassDirectory)"
ClassesZip="$(_AndroidIntermediateClassesZip)"
StubSourceDirectory="$(_AndroidIntermediateJavaSourceDirectory)"
AdditionalStubSourceDirectories="@(_AdditionalJavaStubDirectory)"
JavaSourceFiles="@(_JavaSource)"
ToolPath="$(JavacToolPath)"
ToolExe="$(JavacToolExe)"
Jars="@(_JavaLibrariesToCompile);@(_ReferenceJavaLibs)"
Jars="@(_JavaBindingClassDirectory);@(_JavaLibrariesToCompile);@(_ReferenceJavaLibs)"
JavacTargetVersion="$(JavacTargetVersion)"
JavacSourceVersion="$(JavacSourceVersion)"
JdkVersion="$(_JdkVersion)"
Expand Down
24 changes: 13 additions & 11 deletions src/Xamarin.Android.Build.Tasks/Tasks/D8.cs
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Expand Up @@ -36,7 +36,7 @@ public class D8 : JavaToolTask
public bool EnableDesugar { get; set; } = true;

// Java libraries to embed or reference
public string? ClassesZip { get; set; }
public ITaskItem []? ClassFiles { get; set; }
[Required]
public string JavaPlatformJarPath { get; set; } = "";
public ITaskItem []? JavaLibrariesToEmbed { get; set; }
Expand Down Expand Up @@ -135,21 +135,23 @@ protected virtual string CreateResponseFile ()
}
}

// --lib and input jars
var injars = new List<string> ();
// --lib and program inputs
var inputs = new List<string> ();
var libjars = new List<string> ();
if (ClassFiles != null) {
foreach (var classFile in ClassFiles) {
inputs.Add (classFile.ItemSpec);
}
}
if (AlternativeJarLibrariesToEmbed?.Length > 0) {
Log.LogDebugMessage (" processing AlternativeJarLibrariesToEmbed...");
foreach (var jar in AlternativeJarLibrariesToEmbed) {
injars.Add (jar.ItemSpec);
inputs.Add (jar.ItemSpec);
}
} else if (JavaLibrariesToEmbed != null) {
Log.LogDebugMessage (" processing ClassesZip, JavaLibrariesToEmbed...");
if (!ClassesZip.IsNullOrEmpty () && File.Exists (ClassesZip)) {
injars.Add (ClassesZip);
}
Log.LogDebugMessage (" processing JavaLibrariesToEmbed...");
foreach (var jar in JavaLibrariesToEmbed) {
injars.Add (jar.ItemSpec);
inputs.Add (jar.ItemSpec);
}
}
libjars.Add (JavaPlatformJarPath);
Expand All @@ -163,8 +165,8 @@ protected virtual string CreateResponseFile ()
WriteArg (response, "--lib");
WriteArg (response, jar);
}
foreach (var jar in injars) {
WriteArg (response, jar);
foreach (var input in inputs) {
WriteArg (response, input);
}

return responseFile;
Expand Down
15 changes: 1 addition & 14 deletions src/Xamarin.Android.Build.Tasks/Tasks/Javac.cs
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Expand Up @@ -9,7 +9,6 @@
using Microsoft.Build.Utilities;
using System.Text;
using System.Collections.Generic;
using Xamarin.Tools.Zip;
using Xamarin.Android.Tools;
using Microsoft.Android.Build.Tasks;

Expand All @@ -22,8 +21,6 @@ public class Javac : JavaCompileToolTask
[Required]
public string ClassesOutputDirectory { get; set; } = "";

public string? ClassesZip { get; set; }

public string? JavaPlatformJarPath { get; set; }

public string? JavacTargetVersion { get; set; }
Expand All @@ -37,17 +34,7 @@ public override bool RunTask ()
{
if (!Directory.Exists (ClassesOutputDirectory))
Directory.CreateDirectory (ClassesOutputDirectory);
var result = base.RunTask ();
if (!result)
return result;
// compress all the class files
if (!ClassesZip.IsNullOrEmpty ()) {
using (var zip = new ZipArchiveEx (ClassesZip, FileMode.OpenOrCreate)) {
zip.AutoFlush = false;
zip.AddDirectory (ClassesOutputDirectory, "", CompressionMethod.Store);
}
}
return result;
return base.RunTask ();
}

protected override string GenerateCommandLineCommands ()
Expand Down
26 changes: 24 additions & 2 deletions src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest.cs
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Expand Up @@ -2152,16 +2152,38 @@ public static Toolbar GetToolbar (Context context) {
}
}
",
Encoding = Encoding.ASCII
Encoding = Encoding.ASCII,
Metadata = { { "Bind", "True" } },
},
}
},
Sources = {
new BuildItem.Source ("UseToolbarEx.cs") {
TextContent = () => """
using Android.Content;

class UseToolbarEx
{
public AndroidX.AppCompat.Widget.Toolbar GetToolbar (Context context) =>
Com.Unnamedproject.Unnamedproject.ToolbarEx.GetToolbar (context);
}
""",
},
},
};
proj.SetRuntime (runtime);
proj.PackageReferences.Add (KnownPackages.AndroidXAppCompat);
using (var b = CreateApkBuilder ()) {
b.ThrowOnBuildFailure = false;
Assert.IsTrue (b.Build (proj), "Build should have succeeded");

var intermediate = Path.Combine (Root, b.ProjectDirectory, proj.IntermediateOutputPath);
var bindingJar = Path.Combine (intermediate, "binding", "bin", $"{proj.ProjectName}.jar");
FileAssert.DoesNotExist (bindingJar, "Application builds should pass bound Java class files directly to D8/R8.");
Comment thread
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var dexFile = Path.Combine (intermediate, "android", "bin", "classes.dex");
FileAssert.Exists (dexFile);
Assert.IsTrue (DexUtils.ContainsClass ("Lcom/unnamedproject/unnamedproject/ToolbarEx;", dexFile, AndroidSdkPath),
$"`{dexFile}` should contain the bound Java source.");

Assert.IsTrue (b.Clean (proj), "Clean should have succeeded.");
}
}
Expand Down
33 changes: 14 additions & 19 deletions src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest2.cs
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Expand Up @@ -1432,35 +1432,30 @@ public void BuildIncrementingClassName ([Values (AndroidRuntime.CoreCLR, Android
using (var b = CreateApkBuilder ()) {
Assert.IsTrue (b.Build (proj), "Build should have succeeded.");

var classesZipPath = Path.Combine (Root, b.ProjectDirectory, proj.IntermediateOutputPath, "android", "bin", "classes.zip");
FileAssert.Exists (classesZipPath);
var expectedBuilder = new StringBuilder ();
using (var zip = ZipHelper.OpenZip (classesZipPath)) {
foreach (var file in zip) {
expectedBuilder.AppendLine (file.FullName);
}
}
var expectedZip = expectedBuilder.ToString ();
var classesDirectory = Path.Combine (Root, b.ProjectDirectory, proj.IntermediateOutputPath, "android", "bin", "classes");
DirectoryAssert.Exists (classesDirectory);
var expectedClasses = Directory.GetFiles (classesDirectory, "*.class", SearchOption.AllDirectories)
.Select (path => Path.GetRelativePath (classesDirectory, path))
.OrderBy (path => path)
.ToArray ();
Assert.IsNotEmpty (expectedClasses);

source.Timestamp = null; //Force the file to re-save w/ new Timestamp
Assert.IsTrue (b.Build (proj), "Second build should have succeeded.");

var actualBuilder = new StringBuilder ();
using (var zip = ZipHelper.OpenZip (classesZipPath)) {
foreach (var file in zip) {
actualBuilder.AppendLine (file.FullName);
}
}
var actualZip = actualBuilder.ToString ();
Assert.AreNotEqual (expectedZip, actualZip);
var actualClasses = Directory.GetFiles (classesDirectory, "*.class", SearchOption.AllDirectories)
.Select (path => Path.GetRelativePath (classesDirectory, path))
.OrderBy (path => path)
.ToArray ();
CollectionAssert.AreNotEqual (expectedClasses, actualClasses);

//Build with no changes
Assert.IsTrue (b.Build (proj), "Third build should have succeeded.");
FileAssert.Exists (classesZipPath);
DirectoryAssert.Exists (classesDirectory);

//Clean
Assert.IsTrue (b.Clean (proj), "Clean should have succeeded.");
FileAssert.DoesNotExist (classesZipPath);
DirectoryAssert.DoesNotExist (classesDirectory);
}
}

Expand Down
6 changes: 6 additions & 0 deletions src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/D8Tests.cs
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Expand Up @@ -46,10 +46,12 @@ public void ResponseFileContainsLibAndInputJars ()
var inputJar1 = Path.Combine (tempDir, "input1.jar");
var inputJar2 = Path.Combine (tempDir, "input2.jar");
var libJar1 = Path.Combine (tempDir, "lib1.jar");
var classFile = Path.Combine (tempDir, "Example.class");
File.WriteAllText (platformJar, "mock");
File.WriteAllText (inputJar1, "mock");
File.WriteAllText (inputJar2, "mock");
File.WriteAllText (libJar1, "mock");
File.WriteAllText (classFile, "mock");

var d8Task = new D8TestTask {
BuildEngine = engine,
Expand All @@ -60,6 +62,9 @@ public void ResponseFileContainsLibAndInputJars ()
new TaskItem (inputJar1),
new TaskItem (inputJar2),
},
ClassFiles = new ITaskItem [] {
new TaskItem (classFile),
},
JavaLibrariesToReference = new ITaskItem [] {
new TaskItem (libJar1),
},
Expand Down Expand Up @@ -87,6 +92,7 @@ public void ResponseFileContainsLibAndInputJars ()
// Should contain input jars as direct arguments (no --lib prefix)
Assert.IsTrue (responseFileContent.Any (line => line.Contains ("input1.jar")), "Response file should contain input1.jar");
Assert.IsTrue (responseFileContent.Any (line => line.Contains ("input2.jar")), "Response file should contain input2.jar");
Assert.IsTrue (responseFileContent.Any (line => line.Contains ("Example.class")), "Response file should contain class files");

} finally {
// Clean up response file
Expand Down
4 changes: 2 additions & 2 deletions src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets
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Expand Up @@ -921,7 +921,6 @@ because xbuild doesn't support framework reference assemblies.
<_AndroidIntermediateJavaSourceDirectory>$(IntermediateOutputPath)android\src\</_AndroidIntermediateJavaSourceDirectory>
<_AndroidIntermediateDexOutputDirectory>$(IntermediateOutputPath)android\bin\</_AndroidIntermediateDexOutputDirectory>
<_AndroidIntermediateJavaClassDirectory>$(IntermediateOutputPath)android\bin\classes\</_AndroidIntermediateJavaClassDirectory>
<_AndroidIntermediateClassesZip>$(IntermediateOutputPath)android\bin\classes.zip</_AndroidIntermediateClassesZip>
<_AndroidAotBinDirectory>$(IntermediateOutputPath)aot</_AndroidAotBinDirectory>
<_AndroidResgenFlagFile>$(IntermediateOutputPath)R.cs.flag</_AndroidResgenFlagFile>
<_AndroidResFlagFile>$(IntermediateOutputPath)res.flag</_AndroidResFlagFile>
Expand Down Expand Up @@ -1968,8 +1967,9 @@ because xbuild doesn't support framework reference assemblies.
<_CompileToDalvikInputs>
@(_AndroidMSBuildAllProjects)
;@(_JavaLibrariesToCompileForApp)
;@(_JavaBindingClassFile)
;@(AndroidExternalJavaLibrary)
;$(_AndroidIntermediateClassesZip)
;$(_AndroidCompileJavaStampFile)
;@(ProguardConfiguration)
;@(MultiDexMainDexList)
;$(_AndroidBuildPropertiesCache)
Expand Down
6 changes: 4 additions & 2 deletions src/Xamarin.Android.Build.Tasks/Xamarin.Android.D8.targets
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Expand Up @@ -51,6 +51,8 @@ Copyright (C) 2018 Xamarin. All rights reserved.
<ItemGroup>
<_AndroidD8MapDiagnostics Condition=" '$(AndroidD8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
<_AndroidR8MapDiagnostics Condition=" '$(AndroidR8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
<_JavaClassFile Include="$(_AndroidIntermediateJavaClassDirectory)**\*.class" />
<_JavaClassFile Include="@(_JavaBindingClassFile)" />
<!-- User-authored AndroidJavaSource (Bind != True) is not in the acw-map; pass it to R8 so it
is kept when shrinking is enabled rather than silently removed. -->
<_R8KeepJavaSource Include="@(AndroidJavaSource)" Condition=" '%(AndroidJavaSource.Bind)' != 'True' " />
Expand All @@ -66,7 +68,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
OutputDirectory="$(_AndroidIntermediateDexOutputDirectory)"
Debug="$(AndroidIncludeDebugSymbols)"
JavaPlatformJarPath="$(JavaPlatformJarPath)"
ClassesZip="$(_AndroidIntermediateClassesZip)"
ClassFiles="@(_JavaClassFile)"
JavaLibrariesToEmbed="@(_JavaLibrariesToCompileForApp);"
JavaLibrariesToReference="@(AndroidExternalJavaLibrary)"
EnableDesugar="$(AndroidEnableDesugar)"
Expand Down Expand Up @@ -99,7 +101,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
OutputDirectory="$(_AndroidIntermediateDexOutputDirectory)"
Debug="$(AndroidIncludeDebugSymbols)"
JavaPlatformJarPath="$(JavaPlatformJarPath)"
ClassesZip="$(_AndroidIntermediateClassesZip)"
ClassFiles="@(_JavaClassFile)"
JavaLibrariesToEmbed="@(_JavaLibrariesToCompileForApp)"
AlternativeJarLibrariesToEmbed="@(_AlternativeJarForAppD8)"
JavaLibrariesToReference="@(AndroidExternalJavaLibrary)"
Expand Down
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