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8269113: Javac throws when compiling switch (null) #4679

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@lgxbslgx lgxbslgx commented Jul 4, 2021

Hi all,

When we use switch(null) in the source code, the type of the selector is BottomType.
So the statement Type seltype = selector.type; of the method TransPatterns::handleSwitch will get a BottomType.
Then compiler mistakenly uses this BottomType to construct a new VarSymbol.

            VarSymbol temp = new VarSymbol(Flags.SYNTHETIC,
                    names.fromString("selector" + tree.pos + target.syntheticNameChar() + "temp"),
                    seltype,     // <--------here is a BottomType
                    currentMethodSym);

At last, when the compiler uses the new VarSymbol temp to construct a new JCVariableDecl(the code shown as below), it crashes at the method TreeMaker::Type because the method TreeMaker::Type can't handle the type BottomType.

statements.append(make.at(tree.pos).VarDef(temp, !hasNullCase ? attr.makeNullCheck(selector)
                                                                          : selector));

This patch changes the type from BottomType to syms.objectType and adds the corresponding test.
Thanks for taking the time to review.

Best Regards,
-- Guoxiong


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  • JDK-8269113: Javac throws when compiling switch (null)

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@bridgekeeper bridgekeeper bot commented Jul 4, 2021

👋 Welcome back gli! 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 label Jul 4, 2021
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@openjdk openjdk bot commented Jul 4, 2021

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

  • compiler

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

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@mlbridge mlbridge bot commented Jul 4, 2021

Webrevs

lahodaj
lahodaj approved these changes Jul 7, 2021
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@lahodaj lahodaj left a comment

Looks good to me. Might make sense to submit against openjdk/jdk17 and integrate there?

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@openjdk openjdk bot commented Jul 7, 2021

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

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

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

8269113: Javac throws when compiling switch (null)

Reviewed-by: jlahoda

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 47 new commits pushed to the master branch:

  • d1cecaa: 8269481: SctpMultiChannel never releases own file descriptor
  • 2209e3e: 8270027: ProblemList jdk/jfr/event/oldobject/TestObjectSize.java on macOS-x64
  • 2dc5486: 8267303: Replace MinObjectAlignmentSize usages for non-Java heap objects
  • 3586a23: 8268635: Corrupt oop in ClassLoaderData
  • bffb1a7: 8269923: runtime/jni/checked/TestPrimitiveArrayCriticalWithBadParam.java failed with "FATAL ERROR in native method: Primitive type array expected but not received for JNI array operation"
  • 77a5b7b: 8269761: idea.sh missing .exe suffix when invoking javac on WSL
  • 248aa50: 8269294: Verify_before/after_young_collection should execute all verification
  • 18b80c7: 8269908: Move MemoryService::track_memory_usage call into G1MonitoringScope
  • a685011: 8269022: Put evacuation failure string directly into gc=info log message
  • 72530ef: 8269574: C2: Avoid redundant uncommon traps in GraphKit::builtin_throw() for JVMTI exception events
  • ... and 37 more: https://git.openjdk.java.net/jdk/compare/17f53f2f9c5928395eff9186160924e9a8e9a794...master

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@openjdk openjdk bot added the ready label Jul 7, 2021
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@lgxbslgx lgxbslgx commented Jul 7, 2021

@lahodaj thanks for your review. I will move this patch to JDK 17 later.

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@lahodaj lahodaj commented Jul 7, 2021

I am sorry, but it may not be so simple. I apologize for that, I need to do some more investigations, sorry.

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@lgxbslgx lgxbslgx commented Jul 7, 2021

Never mind. I will continue to contact or assist you in this PR. If the final patch is not large, it could be moved to JDK 17 at last.

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@bridgekeeper bridgekeeper bot commented Aug 4, 2021

@lgxbslgx This pull request has been inactive for more than 4 weeks and will be automatically closed if another 4 weeks passes without any activity. To avoid this, simply add a new comment to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

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@bridgekeeper bridgekeeper bot commented Sep 1, 2021

@lgxbslgx This pull request has been inactive for more than 8 weeks and will now be automatically closed. If you would like to continue working on this pull request in the future, feel free to reopen it! This can be done using the /open pull request command.

@bridgekeeper bridgekeeper bot closed this Sep 1, 2021
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