x/text/encoding/charmap: support for code page `1125` aka `cp866u`

[yukal]

Proposal Details

👋 Hey team,

I'm encountering issues with the charmap package when attempting to decode/encode using code page cp1125. This encoding is missing. Given that some of our Ukrainian projects rely on CP1125, especially when interacting with legacy systems, addressing this would be greatly beneficial.

IBM CP1125 (aka cp866u) is Ukrainian government standard (RST 2018-91) for DOS, based on common "alternative" encoding, but different from cp866 in 0xF2-0xF9. It is known by GNU iconv as CP1125.

• https://public.dhe.ibm.com/software/globalization/gcoc/attachments/CP01125.pdf
• https://public.dhe.ibm.com/software/globalization/gcoc/attachments/CP01125.txt
• https://github.com/unicode-org/icu/blob/main/icu4c/source/data/mappings/ibm-1125_P100-1997.ucm
• https://en.wikipedia.org/wiki/Code_page_866#Ukrainian_and_Belarusian_variants
• https://segfault.kiev.ua/cyrillic-encodings/#ruscii

https://github.com/microsoft/vscode/issues/230438

I'd be happy to provide more details or assist with testing if needed. Thank you for considering this request.

[yukal]

Oh, I little bit confused, should this issue located here, or it should located at https://github.com/golang/text? Ok, I just leave it here, cause I didn't found any issue tracker at https://github.com/golang/text.

[ianlancetaylor]

CC @mpvl

I don't see a reason for this to be in the proposal process. Happy to hear otherwise.