Re: From wchar_t to char32_t

[Paul Eggert]

On 2023-07-04 12:31, Bruno Haible wrote:
> Yes.
>
> As far as I can see, this proposed patch should cope with (size_t) -3
> returns correctly.

I still see a couple of problems with it. First, it mishandles the case 
where mbrtoc32 returns 0, which ISO C allows.

Second and more interestingly, its "fwrite (tp0, 1, bytes, out);" could 
output a byte string that represents multiple characters where the first 
character fits in the output column width but the remaining characters 
do not, and this would exceed the output column width.

I suppose one could fix the second problem by not outputting such a byte 
string, just as the code already suppresses the output of a byte string 
representing a single character that occupies multiple columns 
straddling the column border. That is, count all the columns of all the 
characters that the byte string represents, before deciding whether to 
output the byte string.