Re: From wchar_t to char32_t

[Paul Eggert]

On 2023-07-02 06:33, Bruno Haible wrote:
> +                    else if (bytes == (size_t) -3)
> +                      bytes = 0;

Why is this sort of thing needed?  I thought that (size_t) -3 was 
possible only after a low surrogate, which is possible when decoding 
valid UTF-16 to Unicode, but not when decoding valid UTF-8 to Unicode. 
When can we get (size_t) -3 in a real-world system?

If (size_t) -3 is possible, I suppose I should change diffutils to take 
this into account, as bleeding-edge diffutils/src/side.c treats (size_t) 
-3 as meaning the next input byte is an encoding error, which is 
obviously wrong. The simplest way to fix this would be for diffutils to 
go back to using wchar_t, although I don't know what the downsides of 
that would be (diffutils doesn't care about Unicode; all it cares is 
about is character classes and print widths).