RFR: 8294314: Minimize disabled warnings in hotspot [v4]

[Magnus Ihse Bursie]

On Tue, 27 Sep 2022 12:11:23 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Magnus Ihse Bursie has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Add warnings for additional platforms (thanks shipilev!)
>>  - Revert "Trigger GHA to compile with all warnings before aborting"
>>    
>>    This reverts commit 031acab542c0693d5ee4f90c6f94452206bbb203.
>
> make/hotspot/lib/CompileJvm.gmk line 95:
> 
>> 93: 
>> 94: DISABLED_WARNINGS_clang := ignored-qualifiers sometimes-uninitialized \
>> 95:     missing-braces delete-non-abstract-non-virtual-dtor unknown-pragmas
> 
> Per JDK-9240259, -Wshift-negative-value should remain globally disabled, for
> all of gcc and clang (and xlc, where it hasn't been removed).
> 
> Per discussion for JDK-8211073, -Wempty-body should remain globally disabled
> for gcc.
> 
> As for the other gcc and clang warnings being removed from the globally
> disabled lists, that looks okay to me. I'm particularly happy to see
> -Wstrict-overflow removed from that list, and that we don't seem to have any
> of those any more.
> 
> I've not looked at the changes to warnings for Windows.

You mentioned shift-negative-value earlier in this PR. I apologize I forgot about it.

I can't find any discussion about JDK-8211073 wrt to `-Wempty-body` (are you sure this is the correct bug ID?), but I can put that as well to the globally disabled set.

As for xlc, I have no access to that compiler and I have therefore not done much changes here. But I think xlc compiles with "warnings as errors" off by default so most likely the people still supporting the AIX port don't care that much about warnings.

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PR: https://git.openjdk.org/jdk/pull/10414