Re: mbcel module for Gnulib?, incomplete multibyte sequences

[Paul Eggert]

On 2023-07-24 15:58, Bruno Haible wrote:
> Paul Eggert wrote:
> > in UTF-8 the byte sequence E0 80 is not an incomplete character
> > (in the sense that additional bytes may lead to a complete character),
> > because every byte you append to E0 80 causes glibc mbrtoc32 to return
> > (size_t) -1. Yet glibc mbrtoc32 returns (size_t) -2 for E0 80.
>
> And gnulib/lib/unistr/u8-mbtouc-aux.c does it wrong as well!
> The return value for E0 {80..9F} should be (size_t) -1, because
> U+0800 is E0 A0 80.
>
> I'll fix the gnulib part soon. Very good point. It looks like few people
> understood the implications of
> https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf page 125, table 3-7.

I hope we don't need to replace mbrtoc32 merely because of this obscure 
issue. Or at least if mbrtoc32 can be replaced, I hope an application 
can disable replacement merely because of this issue, assuming the 
application doesn't need to worry about the issue and there is a 
performance benefit to not replacing.