8328649: Disallow enclosing instances for local classes in constructor prologues

[archiecobbs]

A local class declared in a static context is not supposed to have an immediately enclosing instance (§15.9.2). That includes local classes declared in constructors prior to super() (during the "constructor prologue" in the new lingo).

However, the compiler is allowing code like this to successfully compile:

import java.util.concurrent.atomic.*;
public class Test extends AtomicReference<Object> {
  
    public Test() {
        super(switch (0) {
          default -> {
              class Local { { Test.this.hashCode(); } }   // this should fail
              yield null;
            }
        });
    }
}

This patch fixes the "leak".

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires CSR request JDK-8328706 to be approved

Issues

• JDK-8328649: Disallow enclosing instances for local classes in constructor prologues (Bug - P4)
• JDK-8328706: Disallow enclosing instances for local classes in constructor prologues (CSR)

Reviewers

• Vicente Romero (@vicente-romero-oracle - Reviewer)

Reviewing

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$ git fetch https://git.openjdk.org/jdk.git pull/18416/head:pull/18416
$ git checkout pull/18416

Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/18416/head

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$ git pr checkout 18416

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https://git.openjdk.org/jdk/pull/18416.diff

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[bridgekeeper]

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[openjdk]

@archiecobbs This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8328649: Disallow enclosing instances for local classes in constructor prologues

Reviewed-by: vromero

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At the time when this comment was updated there had been 36 new commits pushed to the master branch:

• 4276d5c: 8329637: Apparent typo in java.security file property jdk.tls.keyLimits
• 6382a12: 8326666: Remove the Java Management Extension (JMX) Subject Delegation feature
• d90e5b5: 8329546: Assume sized integral types are available
• f3db279: 8327410: Add hostname option for UL file names
• 21867c9: 8313332: Simplify lazy jmethodID cache in InstanceKlass
• b9da140: 8329594: G1: Consistent Titles to Thread Work Items.
• a169c06: 8329580: Parallel: Remove VerifyObjectStartArray
• 8efd7aa: 8328786: [AIX] move some important warnings/errors from trcVerbose to UL
• f26e430: 8327110: Refactor create_bool_from_template_assertion_predicate() to separate class and fix identical cloning cases used for Loop Unswitching and Split If
• e5e21a8: 8328702: C2: Crash during parsing because sub type check is not folded
• ... and 26 more: https://git.openjdk.org/jdk/compare/6ae1cf12cee268ac7599eb9ade9c0861a89748f9...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (c9d399d7)
• 00: Full (d98cb3d5)

[liach]

Thanks for this change! This unification of outer instance handling of inner and anonymous class declaration paves the way for Valhalla's value classes and makes things more straightforward.

According to #13656 (comment) this change will affect the class file generated, such as for your given example. Should this patch get a CSR then?

[archiecobbs]

According to #13656 (comment) this change will affect the class file generated, such as for your given example. Should this patch get a CSR then?

Well, this change only affects generated classfiles in the sense that it will be no longer possible to generate certain classfiles because compilation will fail instead :)

But regardless I think a CSR is probably warranted so I'll add one. Thanks.

[archiecobbs]

/csr

[openjdk]

@archiecobbs has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@archiecobbs please create a CSR request for issue JDK-8328649 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

[vicente-romero-oracle]

looks good to me

[archiecobbs]

@vicente-romero-oracle, would you (or anyone) mind reviewing the associated CSR per @jddarcy's request?

Thanks.

[vicente-romero-oracle]

@vicente-romero-oracle, would you (or anyone) mind reviewing the associated CSR per @jddarcy's request?

Thanks.

looks good

[vicente-romero-oracle]

/sponsor

[openjdk]

@vicente-romero-oracle The change author (@archiecobbs) must issue an integrate command before the integration can be sponsored.

[archiecobbs]

/integrate

[openjdk]

@archiecobbs
Your change (at version c9d399d) is now ready to be sponsored by a Committer.

[archiecobbs]

Hi @vicente-romero-oracle , thanks for reviewing & sponsoring. Please sponsor one more time as the bot got confused somehow. Thanks.

[vicente-romero-oracle]

/sponsor

[openjdk]

Going to push as commit d80d478.
Since your change was applied there have been 38 commits pushed to the master branch:

• 83eba86: 8329332: Remove CompiledMethod and CodeBlobLayout classes
• 28216aa: 8328366: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501
• 4276d5c: 8329637: Apparent typo in java.security file property jdk.tls.keyLimits
• 6382a12: 8326666: Remove the Java Management Extension (JMX) Subject Delegation feature
• d90e5b5: 8329546: Assume sized integral types are available
• f3db279: 8327410: Add hostname option for UL file names
• 21867c9: 8313332: Simplify lazy jmethodID cache in InstanceKlass
• b9da140: 8329594: G1: Consistent Titles to Thread Work Items.
• a169c06: 8329580: Parallel: Remove VerifyObjectStartArray
• 8efd7aa: 8328786: [AIX] move some important warnings/errors from trcVerbose to UL
• ... and 28 more: https://git.openjdk.org/jdk/compare/6ae1cf12cee268ac7599eb9ade9c0861a89748f9...master

Your commit was automatically rebased without conflicts.

[openjdk]

@vicente-romero-oracle @archiecobbs Pushed as commit d80d478.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.