src/test/java/com/android/tools/r8/ir/optimize/checkcast/CheckCastNullForTypeTest.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.ir.optimize.checkcast;

import static com.android.tools.r8.utils.codeinspector.Matchers.isPresent;
import static junit.framework.TestCase.assertEquals;
import static org.hamcrest.MatcherAssert.assertThat;

import com.android.tools.r8.TestBase;
import com.android.tools.r8.TestParameters;
import com.android.tools.r8.TestParametersCollection;
import com.android.tools.r8.utils.StringUtils;
import com.android.tools.r8.utils.codeinspector.ClassSubject;
import com.android.tools.r8.utils.codeinspector.MethodSubject;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

/** This is a reproduction of b/160856783. */
@RunWith(Parameterized.class)
public class CheckCastNullForTypeTest extends TestBase {

  private final TestParameters parameters;
  private static final String EXPECTED = StringUtils.lines("null", "null");

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

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

  @Test
  public void testRuntime() throws Exception {
    testForRuntime(parameters)
        .addProgramClasses(A.class, Main.class)
        .run(parameters.getRuntime(), Main.class)
        .assertSuccessWithOutput(EXPECTED);
  }

  @Test
  public void testR8() throws Exception {
    testForR8(parameters.getBackend())
        .addProgramClasses(A.class, Main.class)
        .setMinApi(parameters.getApiLevel())
        .addKeepClassAndMembersRules(Main.class)
        .run(parameters.getRuntime(), Main.class)
        .assertSuccessWithOutput(EXPECTED)
        .inspect(
            codeInspector -> {
              ClassSubject main = codeInspector.clazz(Main.class);
              assertThat(main, isPresent());
              MethodSubject mainMethod = main.uniqueMethodWithName("main");
              assertThat(mainMethod, isPresent());
              assertEquals(
                  0,
                  mainMethod
                      .streamInstructions()
                      .filter(instruction -> instruction.isCheckCast(Main.class.getTypeName()))
                      .count());
            });
  }

  public static class A {}

  public static class Main {

    private static void print(Main main) {
      System.out.println(main);
    }

    public static void main(String[] args) {
      A a = null;
      Main main;
      do {
        main = (Main) (Object) a;
      } while ((a = (A) null) != null);
      System.out.println(a);
      print(main);
    }
  }
}