RFR: 8335298: Fix -Wzero-as-null-pointer-constant warning in G1CardSetContainers [v2]

[Albert Mingkun Yang]

On Tue, 2 Jul 2024 07:33:45 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change to the G1CardSetInlinePtr default constructor to
>> avoid -Wzero-as-null-pointer-constant.  The problem is that it is casting a
>> constant 0 to a pointer.  Because casting 0 to a pointer is what this code
>> needs to do, the options are to (1) suppress the warning, or (2) write the
>> code in such a way as to dodge the warning.  We take the latter approach, as
>> it involves less source code clutter.  We expect an optimizing compiler to
>> produce the same code either way.
>> 
>> Also simplified the constructors by using delegation.
>> 
>> Testing: mach5 tier1.
>> Locally (linux-x64) verified the warning no longer occurs with this change.
>
> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
> 
>   change comment to refer to gcc bug

Marked as reviewed by ayang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/19955#pullrequestreview-2153095225