RFR: 8254072: AArch64: Get rid of --disable-warnings-as-errors on Windows+ARM64 build [v4]

[Magnus Ihse Bursie]

On Mon, 2 Nov 2020 16:06:15 GMT, Bernhard Urban-Forster <burban at openjdk.org> wrote:

>> @lewurm 
>> This patch seems to break on linux-aarch64 with gcc:
>> open/src/hotspot/cpu/aarch64/sharedRuntime_aarch64.cpp:1501:52: error: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Werror=sign-compare]
>>  1501 |     assert(StackOverflow::stack_shadow_zone_size() == (int)StackOverflow::stack_shadow_zone_size(), "must be same");
>>       |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> Did you test building this on any aarch64 platforms besides Windows?
>
> @magicus I did test the initial version of this PR on linux+arm64, but not the latest iteration. sorry about that 🙁 
> 
> What is the policy here? Submit a revert right away or investigate a fix?

@lewurm Open a new JBS issue with the bug. If you can find a fix in a short amount of time (which I would believe should be possible; probably just need a proper cast) it's acceptable to fix it directly. What amounts to a "short amount of time" is left to reasonable judgement; minutes to hours are okay, days are not.

Otherwise, create an anti-delta (revert changeset) to back out your changes, and open yet another JBS issue for re-implementing them correctly.  

 In this case, an alternative short-term fix could also be to remove the assert instead of backing out the entire patch.

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PR: https://git.openjdk.java.net/jdk/pull/530