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

[Florian Weimer]

On 11/21/2016 03:05 PM, Zack Weinberg wrote:

> However, it is not clear to me that actual implementations honor that
> requirement.  Consider the case where wchar_t is signed short (this
> hypothetical implementation is limited to the BMP), wint_t is signed
> int, and WEOF == ((wint_t)-1).  Then (wint_t)U+FFFF is
> indistinguishable from WEOF.  Yes, U+FFFF is a reserved codepoint, but
> it's still wrong for it to collide.

That would be consistent with the situation with signed chars and EOF. 
Everyone in a while, someone complains why isalpha ('ÿ') is 0.

Florian