Re: [PATCH 2/2] Include unistd.h.

[Erik Faye-Lund <kusmabite@gmail.com>]

On Wed, May 25, 2011 at 8:30 PM, Junio C Hamano <gitster@pobox.com> wrote:
> mduft@gentoo.org writes:
>
>> At least on Interix, NULL is defined in unistd.h, and not including it
>> causes compilation failure.
>>
>> Signed-off-by: Markus Duft <mduft@gentoo.org>
>> ---
>>  compat/fnmatch/fnmatch.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/compat/fnmatch/fnmatch.c b/compat/fnmatch/fnmatch.c
>> index 14feac7..0238cca 100644
>> --- a/compat/fnmatch/fnmatch.c
>> +++ b/compat/fnmatch/fnmatch.c
>> @@ -25,6 +25,7 @@
>>  # define _GNU_SOURCE 1
>>  #endif
>>
>> +#include <unistd.h>
>>  #include <errno.h>
>>  #include <fnmatch.h>
>>  #include <ctype.h>
>
> The header stddef.h is where NULL is supposed to be defined, and commonly
> used headers are supposed to define NULL the same way as stddef.h does.
> There is a conditional inclusion of stdlib.h in fnmatch.c and stdlib.h is
> one of those files; probably that is how the upstream pulls in NULL when
> compiling this.
>
> But we don't define STDC_HEADERS nor _LIBC (and we shouldn't), so I don't
> know how the existing users of compat/fnmatch/ gets the defintion of NULL
> from. Output from "gcc -E -dD -DNO_FNMATCH compat/fnmatch/fnmatch.c" does
> not seem to show any NULL defined.
>
> Other platforms (e.g. SunOS, IRIX, HPUX, Windows) use NO_FNMATCH_CASEFOLD
> and compile this file.  How are they getting their NULLs?

Windows/MinGW:

$ gcc -E -dD -DNO_FNMATCH compat/fnmatch/fnmatch.c | grep NULL
compat/fnmatch/fnmatch.c:29:21: error: fnmatch.h: No such file or directory
#define __MINGW_ATTRIB_NONNULL(arg) __attribute__ ((__nonnull__ (arg)))
#undef __need_NULL
#define __need_NULL
#undef NULL
#define NULL ((void *)0)
#undef __need_NULL

The "#define NULL ((void *)0)"-line comes from stddef.h, which is
included from string.h, which in turn is included by fnmatch.c.