8378180: Compiling OpenJDK with C23 C-Compiler gives warning: initialization discards ‘const’ qualifier from pointer target type

[fthevenet]

This is an unclean backport of of commit 548d07d3 from the openjdk/jdk repository (itslef a backport of 76a44b3e from openjdk/jdk).

The aim for this backport is to address compiler warnings that arise when attempting to build with with more recent version of gcc (16.1+).

The backport does not apply cleanly, because I had to omit the clean-up of an used variable in log_messages.c that was introduced in jdk 20 as part of JDK-8289768.
I opted to not do a prior backport for JDK-8289768, as it touches quite a large number of files.

I have verified that with this patch, jdk17u-dev compiles without warning on Fedora 44 with gcc 16.1.1.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue
• JDK-8378180 needs maintainer approval

Issue

• JDK-8378180: Compiling OpenJDK with C23 C-Compiler gives warning: initialization discards ‘const’ qualifier from pointer target type (Enhancement - P3 - Approved)

Reviewers

• Andrew John Hughes (@gnu-andrew - Reviewer)

Reviewing

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[openjdk]

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8378180: Compiling OpenJDK with C23 C-Compiler gives warning: initialization discards ‘const’ qualifier from pointer target type

Reviewed-by: andrew

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At the time when this comment was updated there had been 15 new commits pushed to the master branch:

• 4e5bb3d: Merge
• 10cd730: 8386551: Windows build broken because of MSys2/Make update
• 210ff05: 8385490: Update HarfBuzz to 14.2.0
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[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @fthevenet This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

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[fthevenet]

/approval request I'd like to backport this to JDK 17.

Motivation: This patch is needed in order to build jdk17u with more recent version of gcc (16.1.1+), as it fixes compiler warnings.
The backport does not apply cleanly, because I had to omit the clean-up of an used variable in log_messages.c that was introduced in jdk 20 as part of JDK-8289768.
I opted to not do a prior backport for JDK-8289768, as it touches quite a large number of files.

The change introduces no behaviour change and is low risk.

I have verified that with this patch, jdk17u-dev compiles without warning on Fedora 44 with gcc 16.1.1.

[openjdk]

@fthevenet
8378180: The approval request has been created successfully.

[gnu-andrew]

/reviewer 1 reviewer

Not sure why this is being marked clean when it is not clean by the submitter's own admission.

[openjdk]

@gnu-andrew Only the author (@fthevenet) is allowed to issue the reviewer command.

[gnu-andrew]

/reviewers 1 reviewer

[openjdk]

@gnu-andrew
Warning: By issuing the /reviewers command in this clean backport pull request, the reviewers check has now been enabled.
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 1 (with at least 1 Reviewer).

[gnu-andrew]

Patch looks good to me. There's no need to backport a change that just touched the same copyright header and especially not a cleanup one.

Despite the subject, I don't believe this is related to C23, as 17u should be passing -std=c99. It's likely just additional warnings with a newer gcc.

[fthevenet]

Thanks for the review, @gnu-andrew