RFR: 8308286 Fix clang warnings in linux code [v5]

[Daniel Jeliński]

On Sun, 11 Jun 2023 16:38:31 GMT, Artem Semenov <asemenov at openjdk.org> wrote:

>> When using the clang compiler to build OpenJDk on Linux, we encounter various "warnings as errors".
>> They can be fixed with small changes.
>
> Artem Semenov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - update
>  - update
>  - update
>  - update
>  - 8308286 Fix clang warnings in linux code

Please update copyright years where they aren't at 2023 yet.

I verified these changes on Ubuntu 20.04 + clang 10; they are both necessary and sufficient to make the build pass with warnings as errors. I saw one more warning:

clang: warning: argument unused during compilation: '-static-libstdc++' [-Wunused-command-line-argument]

in `BUILD_SYSLOOKUPLIB_link.log`, but that one does not break the build.

I'm going to approve this once you fix the mentioned issues. Thanks for working on this!

make/modules/java.desktop/lib/Awt2dLibraries.gmk line 235:

> 233:         DISABLED_WARNINGS_gcc := int-to-pointer-cast, \
> 234:         DISABLED_WARNINGS_gcc_awt_Taskbar.c := parentheses, \
> 235:         DISABLED_WARNINGS_clang_awt_Taskbar.c := parentheses, \

please group the disabled warnings by compiler (gcc, then clang, then clang_aix)

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PR Review: https://git.openjdk.org/jdk/pull/14033#pullrequestreview-1489972241
PR Review Comment: https://git.openjdk.org/jdk/pull/14033#discussion_r1236510850