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8297974: ClassCastException in #11479

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@lahodaj lahodaj commented Dec 2, 2022

Considering code like:

class RecoveryTest {

    interface I {
        int convert(int i);

    void t(I f, String e) {
        t(param -> param); //a parameter missing here


This is clearly wrong (the invocation of t is missing a parameter). But, running this crashes the compiler in addition to reporting the error:

$ javac -XDdev 
/tmp/ error: method t in class RecoveryTest cannot be applied to given types;
        t(param -> param);
  required: I,String
  found:    (param)->param
  reason: actual and formal argument lists differ in length
1 error
An exception has occurred in the compiler (20-internal). Please file a bug against the Java compiler via the Java bug reporting page ( after checking the Bug Database ( for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
java.lang.ClassCastException: class$JCIdent cannot be cast to class$JCBlock ($JCIdent and$JCBlock are in module jdk.compiler of loader 'app')
        at jdk.compiler/
        at jdk.compiler/

The reason is that AttrRecovery will try to temporarily tweak the AST, so that it can be more correctly attributed. In particular, it will try to add a return statement into the lambda - but as the lambda is not a block lambda, and it crashes.

It seems it is enough to avoid adding the return statement into the expression lambdas, the recovery should still be reasonable, and the crash will be avoided. So, this is what the patch is doing.


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  • JDK-8297974: ClassCastException in



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Update a local copy of the PR:
$ git checkout pull/11479
$ git pull pull/11479/head

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$ git pr checkout 11479

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👋 Welcome back jlahoda! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

@openjdk openjdk bot added the rfr Pull request is ready for review label Dec 2, 2022
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openjdk bot commented Dec 2, 2022

@lahodaj The following label will be automatically applied to this pull request:

  • compiler

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looks good

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openjdk bot commented Dec 2, 2022

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file for details.

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

8297974: ClassCastException in

Reviewed-by: vromero

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 31 new commits pushed to the master branch:

  • 6065696: 8297982: Exclude vmTestbase/nsk/monitoring/stress/lowmem/ with ZGC until 8297979 is fixed
  • 415cfd2: 8297285: Shenandoah pacing causes assertion failure during VM initialization
  • df07255: 8297984: Turn on warnings as errors for javadoc
  • 227364d: 8297953: Fix several C2 IR matching tests for RISC-V
  • 1370228: 8297941: Add override modifier in space.hpp
  • 319faa5: 8296084: javax/swing/JSpinner/4788637/ fails intermittently on a VM
  • b73363f: 8297686: JFR: Improve documentation of EventStream::onMetadata(Consumer)
  • 1376f33: 8297911: Memory leak in JfrUpcalls::on_retransform
  • 5c0ff26: 8291444: GHA builds/tests won't run manually if disabled from automatic running
  • 6d0fbb2: 8297645: Drop the test/jdk/java/net/httpclient/reactivestreams-tck-tests/ test
  • ... and 21 more:

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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Dec 2, 2022
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lahodaj commented Dec 5, 2022


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openjdk bot commented Dec 5, 2022

Going to push as commit 777fb52.
Since your change was applied there have been 50 commits pushed to the master branch:

  • 17666fb: 8297794: Deprecate JMX Management Applets for Removal
  • 619b68c: 8294540: Remove Opaque2Node: it is broken and triggers assert
  • 82561de: 8296384: [TESTBUG] sun/security/provider/SecureRandom/AbstractDrbg/ intermittently timeout
  • 61b7093: 8297872: Non-local G1MonotonicArenaFreePool::_freelist_pool has non-trivial ctor/dtor
  • 3b3bbe5: 8296907: VMError: add optional callstacks, siginfo for secondary errors
  • a573923: 8297264: C2: Cast node is not processed again in CCP and keeps a wrong too narrow type which is later replaced by top
  • b49fd92: 8298055: AArch64: fastdebug build fails after JDK-8247645
  • 914ef07: 8297609: Add application/wasm MIME type for wasm file extension
  • a71d91b: 8298067: Persistent test failures after 8296012
  • 87572d4: 8298068: ProblemList tests failing due to JDK-8297235
  • ... and 40 more:

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Dec 5, 2022
@openjdk openjdk bot closed this Dec 5, 2022
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Dec 5, 2022
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openjdk bot commented Dec 5, 2022

@lahodaj Pushed as commit 777fb52.

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

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