RFR: 8300819: -Dfile.encoding=Cp943C option does not work as expected since jdk18 [v2]

[Alan Bateman]

On Mon, 23 Jan 2023 09:44:48 GMT, Ichiroh Takiguchi <itakiguchi at openjdk.org> wrote:

> Java8 works `-Dfile.encoding=Cp943C` option on Linux. Since many users are migrating from Java8, I'm getting similar requests from my clients. Cp943C is not supported by Linux natively, but some clients want to use same encoding with Linux and AIX.
> 
> Japanese AIX environment supports IBM-943(Cp943C)/IBM-eucJP(Cp29626C)/UTF-8 encoding. Cp943C and Cp29626C are in base.base module on AIX platform.

It's never been supported to run with -Dfile.encoding=Cp943C. It may have worked in JDK 8 but I doubt it could have worked consistently since JDK 9 because the default charset is derived before it's possible to locate charset implementations outside of java.base.

I think it would be useful to know a bit more about the environment. It sounds like it might be AIX -> Linux migration but I'm curious if you have any insight into why these applications depend on default charset being Cp943C. Is it text files that are opened without specifying the charset or is is something else?

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PR: https://git.openjdk.org/jdk/pull/12132