[php-src] Issue #8281: mb_convert_encoding "\" (backslash) and "~" (tilde) convert failed to Shift_JIS

Issue: https://github.com/php/php-src/issues/8281 Comment Author: alexdowad @youkidearitai, Thanks for those references. This was particularly interesting: > > 多くの日本語JISキーボードでは円記号とバックスラッシュのキーが別々に存在しているが、どちらを入力しても005Cが入力されるようになっている。 That is completely insane. Whoever came up with that idea deserves an award for bad design. Thanks also for the reference to the book プログラマのための文字コード入門, though it doesn't seem there is any way I can access a copy right now. I will be in Japan in a few months (COVID-19 situation allowing) and could look it up then, but it would be nice to conclude this issue faster than that. 😆 As we consider this matter further, I think it would also help if you could explain: What is your use case here? How would treating SJIS 0x5C as a halfwidth backslash (U+005C) rather than a Yen sign (U+00A5) affect the software which you are developing or maintaining? What is the typical source of SJIS text data for PHP-based software that you are working on, or are aware of? Text files uploaded by users? Direct text inputs in entry fields on a web site, from users whose OS supports SJIS input? Are we talking about *newly created* data, or *legacy* data which has been around for a long time, but you still need to process?