Spotbugs: Try-with-resources and java9 shows bugs

[ptahchiev]

This is the code:
try (Connection cnn = platformFlyway.getDataSource().getConnection(); Statement st = cnn.createStatement(); ResultSet rs = st.executeQuery(query)) { return processQueryResult(rs); }
Works fine with spotbugs and java8.
With java9 I get this:

````
[INFO] com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl.executeDatabaseQuery(String, boolean) may fail to clean up java.sql.ResultSet [com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl] Obligation to clean up resource created at PlatformServiceImpl.java:[line 641] is not dischargedPath continues at PlatformServiceImpl.java:[line 642]Path continues at PlatformServiceImpl.java:[line 643]Path continues at PlatformServiceImpl.java:[line 642] OBL_UNSATISFIED_OBLIGATION
[INFO] com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl.executeDatabaseQuery(String, boolean) may fail to clean up java.sql.Statement [com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl, com.nemesis.platform.core.service.platform.impl.PlatformServiceImpl] Obligation to clean up resource created at PlatformServiceImpl.java:[line 641] is not dischargedPath continues at PlatformServiceImpl.java:[line 642]Path continues at PlatformServiceImpl.java:[line 643]Path continues at PlatformServiceImpl.java:[line 642] OBL_UNSATISFIED_OBLIGATION
[INFO]

````

[KengoTODA]

Reproduced this problem by unit test. I will attach result of javap:

• java8.txt
• java9.txt

It seems that java9 uses local method Issue493.$closeResource:(Ljava/lang/Throwable;Ljava/lang/AutoCloseable;)V to close AutoCloseable instances.
SpotBugs should handle the second parameter of this method as @WillClose.

  private static void $closeResource(java.lang.Throwable, java.lang.AutoCloseable);
    descriptor: (Ljava/lang/Throwable;Ljava/lang/AutoCloseable;)V
    flags: (0x100a) ACC_PRIVATE, ACC_STATIC, ACC_SYNTHETIC
    Code:
      stack=2, locals=3, args_size=2
         0: aload_0
         1: ifnull        22
         4: aload_1
         5: invokeinterface #1,  1            // InterfaceMethod java/lang/AutoCloseable.close:()V
        10: goto          28
        13: astore_2
        14: aload_0
        15: aload_2
        16: invokevirtual #3                  // Method java/lang/Throwable.addSuppressed:(Ljava/lang/Throwable;)V
        19: goto          28
        22: aload_1
        23: invokeinterface #1,  1            // InterfaceMethod java/lang/AutoCloseable.close:()V
        28: return

private static void $closeResource(java.lang.Throwable t, java.lang.AutoCloseable a)
    throws Exception {
  if (t == null) {
    a.close();
    return;
  }

  try {
    a.close();
  } catch (Throwable e) {
    t.addSuppressed(e);
  }
}

[KengoTODA]

I investigated implementation of BuildObligationPolicyDatabase, and found that we cannot support this case $closeResource.

I expected that change like 138729ba91b77d9690588c0e2c0213f570ccbc2a can treat the parameter of $closeResource as annotated with @WillClose. But I found that this change does not as I expected; it mark variable closed only when variable's type is same with method parameter's type. In other words, type of Obligation#className is now java.lang.AutoCloseable but type of variables are java.sql.Connection etc. In my understanding, there is no prepared way to fill this gap.

[tokuhirom]

What's the current status of this issue?

[KengoTODA]

No update. Currently nobody can propose solution for this issue.

[mattnelson]

No update. Currently nobody can propose solution for this issue.

Can a solution be influenced from jacoco? https://github.com/jacoco/jacoco/pull/669

[davidlinse]

Are there any news on this ?

[KengoTODA]

note: The class file built by Java 11.0.7 (AdoptOpenJDK 11.0.7+10). As described at https://github.com/jacoco/jacoco/pull/669 we have no $closeResource method.

• java11.txt

I guess that this issue does not exist in the latest Java 11 release.