Re: [HACKERS] Unicode combining characters

> > After applying your patches, do the 4-bytes UTF-8 convert to UCS-2 (2
> > bytes) or UCS-4 (4 bytes) in pg_utf2wchar_with_len()? If it were 4
> > bytes, we are in trouble. Current regex implementaion does not handle
> > 4 byte width charsets.
>
> *sigh* yes, it does encode to four bytes :(
>
> Three solutions then :
>
> 1) we support these supplementary characters, knowing that they won't
>    work with regexes,
>
> 2) I back out the change, but then anyone using these characters will
>    get something weird, since the decoding would be faulty (they would
>    be handled as 3 bytes UTF-8 chars, and then the fourth byte would
>    become a "faulty char"... not very good, as the 3-byte version is
>    still not a valid UTF-8 code !),
>
> 3) we fix the regex engine within the next 24 hours, before the beta
>    deadline is activated :/
>
> I must say that I doubt that anyone will use these characters in the
> next few months : these are mostly chinese extended characters, with
> old italic, deseret, and gothic scripts, and bysantine and western
> musical symbols, as well as the mathematical alphanumerical symbols.
>
> I would prefer solution 1), as I think it is better to allow these
> characters, even with a temporary restriction on the regex, than to
> fail completely on them. As for solution 3), we may still work at it
> in the next few months :) [I haven't even looked at the regex engine
> yet, so I don't know the implications of what I have just said !]
>
> What do you think ?

I think 2) is not very good, and we should reject these 4-bytes UTF-8
strings. After all, we are not ready for them.

BTW, other part of your patches looks good. Peter, what do you think?
--
Tatsuo Ishii