RFR: 8299811: SHIFT_JIS compatible charsets should be in java.base module on Linux platform

[Naoto Sato]

On Mon, 9 Jan 2023 17:28:20 GMT, Ichiroh Takiguchi <itakiguchi at openjdk.org> wrote:

> On Japanese environment, following SHIFT_JIS compatible charsets are there:
> * PCK (x-PCK)
> * MS932 (windows-31j)
> * IBM943C (x-IBM943C)
> 
> According to make/data/charsetmapping/charsets,
> PCK and MS932 are independent charset and have no dependencies on others.
> 
> On RHEL8, SHIFT_JIS encoding is supported
> 
> $ env LANG=ja_JP.sjis locale charmap
> SHIFT_JIS
> 
> According to make/data/charsetmapping/stdcs-linux,
> SJIS (SHIFT_JIS) is in there, also MS932 and PCK are there.
> This means these are in java.base module on Linux platform.
> But IBM943C is not in stdcs-linux.
> I think IBM943C also should be in java.base module because of compatibility.

I think the general consensus is to keep the `java.base` module minimal. IIRC, the reason we have `PCK` charsets in Un*x platforms was that it was required to boot Solaris in Japanese env (sorry if I am wrong). So I would remove it from `java.base` if possible. Thus moving those IBM* encodings that are equivalent to SJIS into `java.base` is something I would not want to do. It is definitely not a compatibility issue.

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PR: https://git.openjdk.org/jdk/pull/11908