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Date: Wed, 13 May 2009 20:04:06 +0100
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Subject: Re: [Fwd: [1.7] wcwidth failing configure tests]
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
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2009/5/12 Corinna Vinschen:
>> Trouble is, there's the thorny issue of the "CJK Ambiguous Width"
>> category of characters, which consists of things like Greek and
>> Cyrillic letters as well as line drawing symbols. Those have a width
>> of 1 in Western use, yet with CJK fonts they have a width of 2. That's
>> why Markus Kuhn's code includes the mk_wcswidth_cjk() variant.
>
> We should use the standard variation alone, imho.

I'm not sure that CJK users would be happy with that. See MinTTY issue
88 for my misguided attempts to dismiss this as a legacy issue:
http://code.google.com/p/mintty/issues/detail?id=3D88

In comment 8 on that, "deenheart" mentioned that he was working on a
fix for wcwidth(). I don't know what he had in mind, but I'd suspect
something based on an environment variable setting.

> And we need some workaround for UTF-16 systems like Cygwin.
> Unfortunately, surrogate pairs only work well as part of a string, not
> as standalone chars. =C2=A0So wcwidth would return -1 for each single cha=
r,
> but wcswidth could be tweaked to handle them gracefully.

Looking at the ranges in wcwidth.c, it might be possible to decide the
width of a surrogate pair based on the high surrogate only, and then
treat the low surrogate as a combining character with length 0.

Andy

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