The isspace(3) man page is badly out of date (newlib)

[Brian Inglis]

On 2026-08-07 16:06, Keith Thompson via Cygwin wrote:
> On Fri, Aug 7, 2026 at 1:28 PM Keith Thompson
> <Keith.S.Thompson@gmail.com> wrote:
>>
>> The `isspace(3)` man page is badly out of date.
>>
>> "isspace is a macro which classifies singlebyte charset values by
>> table lookup. It is a predicate returning non-zero for whitespace
>> characters, and 0 for other characters. It is defined only when
>> isascii(c) is true or c is EOF."
>>
>> In fact, the ISO C standard, since C89/C90, requires that isspace(c)
>> is defined when c either representable as an unsigned char or equal to
>> EOF; the behavior is undefined for any other value.
>>
>> And the actual implementation of isspace() satisfies this requirement.
>> Only the man page is out of date.
>>
>> The man page is generated from newlib/libc/ctype/isspace.c in the
>> newlib git repo, <https://sourceware.org/git/newlib-cygwin.git>.
>>
>> This only affects the isspace(3) man page.  The other is*(3) man pages
>> are correct.
>>
>> A couple of minor points affecting all the <ctype.h> functions/macros:
>>
>> There are two occurrences of "#include <ctype.h>" in the SYNOPSIS
>> section.  The second occurrence is indented too far:
>>
>> SYNOPSIS
>>       #include <ctype.h>
>>
>>       int isspace(int c);
>>
>>                   #include <ctype.h>
>>
>>       int isspace_l(int c, locale_t locale);
>>
>> A lot of library man pages refer to "ANSI C".  "ISO C" would be
>> more accurate.  The term "ANSI C" is ambiguous.  Since 1990, the
>> C standard is controlled by ISO; ANSI adopts each ISO C standard
>> after it's published.
> 
> I've reported this, with a proposed patch, to the
> newlib@sourceware.org mailing list.
> 
> https://sourceware.org/pipermail/newlib/2026/022575.html

The correct wording appears in the isspace(3p) man page when Cygwin package
man-pages-posix is installed (this is the 2018 SUSv4 release, as POSIX has not 
yet publicly released the SUSv5 2024 man pages, although isspace(3p) has not 
changed since SUSv3 Issue 6 2001, but isspace_l(3p) was added in SUSv4 Issue 7 
2018).

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher  but when there is no more to cut
                                 -- Antoine de Saint-Exupéry