8337787: Fix -Wzero-as-null-pointer-constant warnings when JVMTI feature is disabled

[kimbarrett]

Please review this trivial change that replaces some uses of literal 0 as a
null pointer constant when JVMTI is disabled to instead use nullptr.

Testing: mach5 tier1

---

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

Issue

• JDK-8337787: Fix -Wzero-as-null-pointer-constant warnings when JVMTI feature is disabled (Enhancement - P4)

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)
• Serguei Spitsyn (@sspitsyn - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/20455/head

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[openjdk]

@kimbarrett 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:

8337787: Fix -Wzero-as-null-pointer-constant warnings when JVMTI feature is disabled

Reviewed-by: ayang, sspitsyn

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At the time when this comment was updated there had been 3 new commits pushed to the master branch:

• fbe8a81: 8333144: docker tests do not work when ubsan is configured
• dabdae6: 8334599: Improve code from JDK-8302671
• 8bd3cd5: 8337716: ByteBuffer hashCode implementations are inconsistent

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (fe35c76a)

[sspitsyn]

Looks good and trivial.

[kimbarrett]

Thanks for reviews @albertnetymk and @sspitsyn

[kimbarrett]

/integrate

[openjdk]

Going to push as commit 42652b2.
Since your change was applied there have been 13 commits pushed to the master branch:

• 807186f: 8337784: Fix simple -Wzero-as-null-pointer-constant warnings in linux/posix code
• e68df52: 8337054: JDK 23 RDP2 L10n resource files update
• 9856216: 8336928: GHA: Bundle artifacts removal broken
• 219e1eb: 8337712: Wrong javadoc in java.util.Date#toString(): "61" and right parenthesis
• 97afbd9: 8336410: runtime/NMT/TotalMallocMmapDiffTest.java Total malloc diff is incorrect. Expected malloc diff range
• c095c0e: 8336489: Track scoped accesses in JVMCI compiled code
• 7e925d7: 8337283: configure.log is truncated when build dir is on different filesystem
• 2e093b0: 8337779: test/jdk/jdk/jfr/jvm/TestHiddenWait.java is a bit fragile
• d3e7b0c: 8336462: ConcurrentSkipListSet Javadoc incorrectly warns about size method complexity
• be34730: 8335257: Refactor code to create Initialized Assertion Predicates into separate class
• ... and 3 more: https://git.openjdk.org/jdk/compare/367e0a65561f95aad61b40930d5f46843fee3444...master

Your commit was automatically rebased without conflicts.

[openjdk]

@kimbarrett Pushed as commit 42652b2.

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