🐛 Borders displayed too long in environment with East Asian Ambiguous Width == 2

[aoyama-val]

A lot of CJK environments assume that East Asian Ambiguous Width characters are double width, whereas Eastern enviroments single. In former, the borders are displayed with double width and wrapped.It would be preferrable if there was an option to treat those characters as double width or to use ASCII characters to draw borders.

To reproduce:

• Use a terminal that is configurable so that Ambiguous Width characters are double width (e.g. iTerm2)

[th1000s]

I see, delta is using ambiguous chars there, e.g. ─ BOX DRAWINGS LIGHT HORIZONTAL, full list at https://www.unicode.org/reports/tr11-2/.

Also, when determining the width of chars in the diff itself UnicodeWidthStr::width() is always called with no option to switch to width_cjk(). This is most noticeable in side-by-side views so you may also have seen that.

[th1000s]

FTR: On Linux, GNOME Terminal supports setting ambiguous chars to double width (have not found other terms yet). Preferences -> Profile -> Tab "Compatibility" -> Ambiguous-width characters: Wide