Re: [PATCH] mbrlen, mbrtowc: fix bug with empty input

[Paul Eggert]

Pádraig Brady wrote:
> To me, mbrtowc returning 0 for empty input is not surprising.
> Also POSIX says for mbr{len,towc} that they shall return 0
> "If the next n or fewer bytes complete the character that corresponds to the 
> null wide character

At least 1 byte is needed to represent a null wide character. 
Therefore, zero bytes cannot possibly complete a null wide character, 
which means mbrtowc on empty input cannot return 0 if it wants to 
conform to POSIX and/or C11.

A similar argument shows why mbrtowc can't return (size_t) -1 on empty 
input: it's because you need at least 1 byte to represent an encoding error.

Thanks for the typo fix, by the way.