Re: column numbers for non-ASCII characters in error messages

[Ben Pfaff]

Bruno Haible <address@hidden> writes:

> For this reason, the second definition is the one that is normally
> agreed upon. Note, however, that it is ambiguous: For "ambiguous width"
> Unicode characters, the width may depend on the terminal emulator or
> on the locale. But this is not a big problem in practice, because such
> characters occur rarely.
>
> This notion of width, measured by screen columns, is implemented by
>   - the POSIX function wcwidth(),
>   - the gnulib function mbswidth() (applicable to multibyte strings),
>   - the gnulib or libunistring function u8_strwidth() (applicable to UTF-8
>     strings).

Bruno and John, thanks for the additional comments.  It seems
clear that display width is the correct metric here.

I'm going to use a wrapper around uc_width() from libunistring
that is similar to u8_width() but handles tabs.
-- 
Ben Pfaff 
http://benpfaff.org