Signedness of wchar_t and wint_t leads to problems with gcc -Wsign-conversion

[Andreas Schwab]

On Nov 21 2016, "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> wrote:

> However, we don't have a similar solution for iswlower(), because
> there is no "(unsigned wchar_t)" cast. And casting to (wint_t) seems
> incorrect to me, because if wchar_t is a signed type smaller than
> wint_t, then sign extension could occur.

wint_t is "an integer type capable of storing any valid value of wchar_t
or WEOF".  If the sign-extended value of a wchar_t isn't a valid value
then you have undefined behaviour.  WEOF must be defined such that no
conflict can occur with any valid wchar_t value.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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