checker/tests/mustcall/LogTheSocket.java

// This test case was intended to simulate the code below, which issued
// a false positive at the call to LOG.warn() because the socket is @MustCall("close"):
//
//     synchronized void closeSockets() {
//       for (ServerSocket serverSocket : serverSockets) {
//           if (!serverSocket.isClosed()) {
//               try {
//                   serverSocket.close();
//               } catch (IOException e) {
//                   LOG.warn("Ignoring unexpected exception during close {}", serverSocket, e);
//               }
//           }
//       }
//    }
//

import java.io.IOException;
import java.net.ServerSocket;
import java.nio.channels.SocketChannel;
import org.checkerframework.checker.mustcall.qual.*;

class LogTheSocket {

  @NotOwning ServerSocket s;

  @MustCall("") Object s2;

  void testAssign(@Owning ServerSocket s1) {
    s = s1;
    // :: error: assignment
    s2 = s1;
  }

  void logVarargs(String s, Object... objects) {}

  void logNoVarargs(String s, Object object) {}

  void test(ServerSocket serverSocket) {
    if (!serverSocket.isClosed()) {
      try {
        serverSocket.close();
      } catch (IOException e) {
        logVarargs("Ignoring unexpected exception during close {}", serverSocket, e);
      }
    }
  }

  void test2(ServerSocket serverSocket) {
    if (!serverSocket.isClosed()) {
      try {
        serverSocket.close();
      } catch (IOException e) {
        logNoVarargs("Ignoring unexpected exception during close {}", serverSocket);
      }
    }
  }

  // This is (mostly) copied from ACSocketTest; under a previous implementation of the
  // ownership-transfer scheme,
  // it caused false positive warnings from the Must Call checker.
  SocketChannel createSock() throws IOException {
    SocketChannel sock;
    sock = SocketChannel.open();
    sock.configureBlocking(false);
    sock.socket().setSoLinger(false, -1);
    sock.socket().setTcpNoDelay(true);
    return sock;
  }

  @SuppressWarnings("mustcall") // https://github.com/typetools/checker-framework/pull/3867
  void testPrintln(ServerSocket s) {
    System.out.println(s);
  }
}