RFR: 8286775: Remove identical per-compiler definitions of unsigned integral jtypes

[David Holmes]

On Tue, 24 Jan 2023 16:03:24 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Trivial update to share the common typedef's.
>> 
>> Testing: 
>>   - Oracle tier 1 - 5 builds
>>   - GHA (TBD)
>> 
>> Thanks.
>
> `using` declarations are intended to be permitted by the Style Guide. (I know
> what I intended when I wrote the relevant part.) It seems that's ambiguous
> though. The Style Guide has this:
> 
> * Template aliases (n2258)
> 
> That paper also introduced the term "alias declaration", for a non-templated
> `using` type declaration.  So the Style Guide should probably say "Alias
> declarations and template aliases".
> 
> `using Foo = xxx` is equivalent to `typedef xxx Foo`. The former can be easier
> to read, as it's easier to find the identifier being declared, esp. when the
> `xxx` part is long and complex and perhaps even multi-line.
> 
> But I understand the consistency with surrounding code argument.
> 
> `std::make_unsigned` is in <type_traits>, which we're allowed to use. But I
> don't think it's really helpful in this case for readability. We know what the
> representation for these is, since the signed types are defined by the Java
> language.
> 
> Also, the compilation failures are a result of using `std::make_unsigned`.
> I'm not feeling like digging into exactly why.

Thanks for the additional explanations @kimbarrett !

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PR: https://git.openjdk.org/jdk/pull/12136