System.exit()

Nobody has claimed this yet.

I've found a case, that is not handled properly (I think). I expect the JVM to shutdown when I call System.exit(1); and therefore I'd expect this statement to behave as a control-flow guard, similar to putting there a return;. But it is ignored.

@Nullable CommandsGroup commandBean = getCommandBean(commandNameParts[0], context);
if (commandBean == null) {
    System.err.println("Command " + commandName + " not found.");
    System.exit(1);
}

commandBean.runCommand(commandNameParts[1], context.getBean(ApplicationArguments.class));

produces

[ERROR] ConsoleApplication.java:[54,24] [NullAway] dereferenced expression commandBean is @Nullable
    (see http://t.uber.com/nullaway )

The fix in my code is trivial

@Nullable CommandsGroup commandBean = getCommandBean(commandNameParts[0], context);
if (commandBean == null) {
    System.err.println("Command " + commandName + " not found.");
    System.exit(1);

} else {
    commandBean.runCommand(commandNameParts[1], context.getBean(ApplicationArguments.class));
}

Alternatively this

@Nullable CommandsGroup commandBean = getCommandBean(commandNameParts[0], context);
if (commandBean == null) {
    System.err.println("Command " + commandName + " not found.");
    System.exit(1);
    return;
}

commandBean.runCommand(commandNameParts[1], context.getBean(ApplicationArguments.class));

But IMHO this is something the NullAway should handle.

I wasn't looking very hard, but I don't believe there is a way to escape the System.exit(1); (apart from the shutdown handler hook, that is executed in different thread and there doesn't affect the method and thread calling the exit).

maven: effective pom

    <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.0</version>
        <dependencies>
          <dependency>
            <groupId>org.codehaus.plexus</groupId>
            <artifactId>plexus-compiler-javac-errorprone</artifactId>
            <version>2.8.5</version>
            <scope>compile</scope>
          </dependency>
          <dependency>
            <groupId>com.google.errorprone</groupId>
            <artifactId>error_prone_core</artifactId>
            <version>2.3.3</version>
            <scope>compile</scope>
          </dependency>
        </dependencies>
        <configuration>
          <compilerId>javac-with-errorprone</compilerId>
          <forceJavacCompilerUse>true</forceJavacCompilerUse>
          <source>1.8</source>
          <target>1.8</target>
          <compilerArgs>
            <arg>-Werror</arg>
            <arg>-Xlint:all,-fallthrough,-processing,-serial,-classfile</arg>
            <arg>-parameters</arg>
            <arg>-XDcompilePolicy=simple</arg>
            <arg>-Xep:NullAway:ERROR</arg>
            <arg>-XepOpt:NullAway:AnnotatedPackages=com.cogvio.dl</arg>
            <arg>-XepOpt:NullAway:TreatGeneratedAsUnannotated=true</arg>
            <arg>-XepOpt:NullAway:AcknowledgeRestrictiveAnnotations=true</arg>
          </compilerArgs>
          <annotationProcessorPaths>
            <path>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-configuration-processor</artifactId>
              <version>2.2.0.M1</version>
            </path>
            <path>
              <groupId>org.springframework</groupId>
              <artifactId>spring-context-indexer</artifactId>
              <version>5.2.0.M1</version>
            </path>
            <path>
              <groupId>com.uber.nullaway</groupId>
              <artifactId>nullaway</artifactId>
              <version>0.7.2</version>
            </path>
          </annotationProcessorPaths>
          <showWarnings>true</showWarnings>
          <parameters>true</parameters>
        </configuration>
      </plugin>

Start with NullAway's analysis of the Java System.exit(1) call and determine whether it models that call as terminating control flow. Add coverage for the shown nullable dereference case and verify that the diagnostic is not emitted after exit; the issue names no repository file or test.

Written by the indexing model from the issue text.

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