Upstream maintainer here.
I added the missing include.
But I am unsure what to do about the other point (regarding gcc
-Wconversion). There is an analogous situation with islower() and
similar functions, where the solution is described by an update I
recently added for the upcoming upstream release
The standards require that the argument c for these functions is
either EOF or a value that is representable in the type unsigned
char. If the argument c is of type char, it must be cast to
unsigned char, as in the following example:
char c;
...
res = toupper((unsigned char) c);
This is necessary because char may be the equivalent signed char,
in which case a byte where the top bit is set would be sign
extended when converting to int, yielding a value that is outside
the range of unsigned char.
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.
I could be wrong, but it seems like an implementation bug that one of
these types is signed and the other is unsigned.
Cheers,
Michael
