PR lib/57798
Digit value specified by TODIGIT is storaged as lowest 8 bits of
_RuneType, see lib/libc/locale/runetype_file.h:
https://nxr.netbsd.org/xref/src/lib/libc/locale/runetype_file.h#56
The symptom reported in the PR is due to missing range check for
this value; values of 256 and above were mistakenly treated as
other flag bits in _RuneType.
For example, U+5146 has numerical value 1000,000,000,000 ==
0xe8d4a51000 where __BITS(30, 31) == _RUNETYPE_SW3 are turned on.
This is why wcwidth(3) returned 3 for this character.
This apparently affected not only character width, but also other
attributes storaged in _RuneType.
IIUC, digit value attributes in _RuneType have never been utilized
until now, but preserve these if digit fits within (0, 256). This
should be safer for pulling this up into netbsd-10. Also, these
attributes may be useful to implement some I18N features as
suggested by uwe@ in the PR.
netbsd-[98] is not affected as these use old UTF-8 ctype definitions.
1246b914bd