src/test/java/com/android/tools/r8/classmerging/vertical/LambdaRewritingTest.java

// Copyright (c) 2020, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.classmerging.vertical;

import com.android.tools.r8.NeverInline;
import com.android.tools.r8.TestBase;
import com.android.tools.r8.TestParameters;
import com.android.tools.r8.TestParametersCollection;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;

@RunWith(Parameterized.class)
public class LambdaRewritingTest extends TestBase {

  private final TestParameters parameters;

  @Parameterized.Parameters(name = "{0}")
  public static TestParametersCollection data() {
    return getTestParameters().withAllRuntimesAndApiLevels().build();
  }

  public LambdaRewritingTest(TestParameters parameters) {
    this.parameters = parameters;
  }

  @Test
  public void test() throws Exception {
    testForR8(parameters.getBackend())
        .addInnerClasses(getClass())
        .addKeepMainRule(Main.class)
        .addVerticallyMergedClassesInspector(
            inspector -> inspector.assertMergedIntoSubtype(Interface.class))
        .enableInliningAnnotations()
        .setMinApi(parameters.getApiLevel())
        .compile()
        .run(parameters.getRuntime(), Main.class);
  }

  public static class Main {

    public static void main(String[] args) {
      Interface obj = new InterfaceImpl();

      // Leads to an invoke-custom instruction that mentions the type of `obj` since it is captured.
      invoke(() -> obj.foo());

      FunctionImpl functionImpl = new FunctionImpl();
      if (System.currentTimeMillis() < 0) {
        System.out.println(functionImpl);
      }
    }

    @NeverInline
    private static void invoke(Function f) {
      f.accept();
    }
  }

  // Cannot be merged as it has two subtypes: FunctionImpl and a lambda.
  public interface Function {

    void accept();
  }

  public static class FunctionImpl implements Function {

    @Override
    public void accept() {
      System.out.println("In FunctionImpl.accept()");
    }
  }

  // Will be merged into InterfaceImpl.
  public interface Interface {

    void foo();
  }

  public static class InterfaceImpl implements Interface {

    @Override
    public void foo() {
      System.out.println("In InterfaceImpl.foo()");
    }
  }
}