bug#65816: 27.2, 28.2, 29.2; Quail-based Japanese conversion error

[Eli Zaretskii <eliz@gnu.org>]

merge 65816 65815
thanks

> From: Hippo Man <hippoman@gmail.com>
> Date: Thu, 7 Sep 2023 23:58:33 -0400
> 
> The following error that I am reporting appears in emacs-27.2, emacs-28.2, and emacs-29.2.
> 
> This error report is written under the assumption that the reader is familiar with Quail
> and with Japanese syllabary.
> 
> When using (set-language-environment "Japanese") and (set-input-method "japanese") with Quail,
> when we type romaji, the displayed text is correctly converted to hiragana. If we want to
> convert the hiragana to katakana, we just follow the hiragana with "K", and the text display
> is correctly toggled to katakana. Typing "K" again will correctly toggle back to hiragana.
> 
> In most cases, this indeed works correctly. For example, typing "hoteru" correctly yields
> the hiragana "ほてる", and then following that with "K" switches it correctly to the katakana
> "ホテル". And then following that again with "K" correctly toggles it back to "ほてる".
> 
> However, when the word contains an embedded hyphen, the "K" toggling does not work properly.
> 
> For example, typing "ko-to" correctly yields the hiragana "こーと", and then typing "K"
> correctly converts it to the katakana "コート". But then, if I type "K" again, the word does
> not get converted back to hiragana, and the katakana form remains.
> 
> This erroneous behavior occurs with all katakana text which contains one or more embedded
> hyphens. The existence of a hyphen anywhere in the text prevents that text from being
> toggled from katakana to hiragana when "K" is typed.
> 
> Can anyone suggest a way that this incorrect behavior can be fixed?

You have reported 10 minutes ago an identical bug report with a
different email address.  I'm merging the two bugs.