JDK-8289894: A NullPointerException thrown from guard expression

[lahodaj]

Consider the following code:

public class SwitchGuard {
    public static void main(String... args) {
        test(null);
    }
    private static void test(Object o) {
        switch (o) {
            case null, String s when s.isEmpty() -> System.err.println("OK.");
            default -> {}
        }
    }
}

In the current specification, the guard should not be invoked when o is null, but javac will invoke it, for historical reasons.

Also, as opposed to JDK 18/JEP 420, case null, <pattern> is allowed for parenthesized pattern when the parenthesized pattern encloses (directly or via other parenthesized patterns) a type pattern.

The patch proposed here strives to fix both of these problems.

---

Progress

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• Commit message must refer to an issue

Issue

• JDK-8289894: A NullPointerException thrown from guard expression

Reviewers

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

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk19 pull/120/head

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$ git pr checkout 120

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[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (ea7cde94)

[biboudis]

LGTM 🎉

[vicente-romero-oracle]

looks sensible

[openjdk]

@lahodaj 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:

8289894: A NullPointerException thrown from guard expression

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 9 new commits pushed to the master branch:

• 460d879: 8289601: SegmentAllocator::allocateUtf8String(String str) should be clarified for strings containing \0
• 732f106: 8289223: Canonicalize header ids in foreign API javadocs
• ea21c46: 8289799: Build warning in methodData.cpp memset zero-length parameter
• 6428607: 8289030: [macos] app image signature invalid when creating DMG or PKG
• 1304390: 8289951: ProblemList jdk/jfr/api/consumer/TestRecordingFileWrite.java on linux-x64 and macosx-x64
• 11319c2: 8278469: Test java/nio/channels/FileChannel/LargeGatheringWrite.java times out
• 3212dc9: 8289486: Improve XSLT XPath operators count efficiency
• a8eb728: 8289779: Map::replaceAll javadoc has redundant @throws clauses
• 889150b: 8289558: Need spec clarification of j.l.foreign.*Layout

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[lahodaj]

/integrate

[openjdk]

Going to push as commit 25f4b04.
Since your change was applied there have been 14 commits pushed to the master branch:

• b542bcb: 8289729: G1: Incorrect verification logic in G1ConcurrentMark::clear_next_bitmap
• c86c51c: 8282071: Update java.xml module-info
• 9981c85: 8290033: ProblemList serviceability/jvmti/GetLocalVariable/GetLocalWithoutSuspendTest.java on windows-x64 in -Xcomp mode
• c142fbb: 8289697: buffer overflow in MTLVertexCache.m: MTLVertexCache_AddGlyphQuad
• eeaf0bb: 8289872: wrong wording in @param doc for HashMap.newHashMap et. al.
• 460d879: 8289601: SegmentAllocator::allocateUtf8String(String str) should be clarified for strings containing \0
• 732f106: 8289223: Canonicalize header ids in foreign API javadocs
• ea21c46: 8289799: Build warning in methodData.cpp memset zero-length parameter
• 6428607: 8289030: [macos] app image signature invalid when creating DMG or PKG
• 1304390: 8289951: ProblemList jdk/jfr/api/consumer/TestRecordingFileWrite.java on linux-x64 and macosx-x64
• ... and 4 more: https://git.openjdk.org/jdk19/compare/8dd94a2c14f7456b3eaf3e02f38d9e114eb8acc3...master

Your commit was automatically rebased without conflicts.

[openjdk]

@lahodaj Pushed as commit 25f4b04.

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