Re: iconv(3) protype mismatch with POSIX

[Kamil Rytarowski <n54%gmx.com@localhost>]

On 16.06.2016 20:16, David Holland wrote:
> On Thu, Jun 16, 2016 at 12:27:47PM +0200, Kamil Rytarowski wrote:
>  > >  > This is an interesting exercise to use C11.. however:
>  > >  > 1. Not all ports moved to gcc 4.9+,
>  > >  > 2. pcc doesn't support it,
>  > >  > 3. it won't work as a valid and acceptable C++ code.
>  > >  > 4. Many software expects system headers to be C89, GNU89 etc, and
>  > >  > doesn't request C11.
>  > > 
>  > > None of that matters, it just needs to be wrapped in suitable ifdefs.
>  > 
>  > All of them matters to me and C11 in a public-header is no-go.
> 
> Uh, I don't follow. What's wrong with
> 
> #if defined(_NETBSD_SOURCE_) && \
>     defined(__GNUC_PREREQ__(5,3)) && !defined(__cplusplus)
> (polymorphic iconv as suggested)
> #else
> (posix iconv)
> #endif
> 
> ?
> 

I understood that the default-fallback one will be the non complainant one.

Is it going to be a temporary solution?

_Generic is available since GCC-4.9, a more portable implementation is
to use __builtin_constant_p + __builtin_choose_expr... however there are
still plenty of compilers without support for similar features (like PCC).

In C++ there is a polymorphic solution out-of-the-box in C++98 with
function overloading.

>  > > "extern" option?
>  > 
>  > NAME
>  > 
>  > iconv - code conversion function
>  > 
>  > SYNOPSIS
>  > 
>  >    Default
>  > 
>  > #include <iconv.h>
>  > 
>  > extern size_t iconv(iconv_t cd, const char **restrict inbuf,
>  > size_t *restrict inbytesleft, char **restrict outbuf,
>  > size_t *restrict outbytesleft);
>  > 
>  > 
>  > SUSv3
>  > #include <iconv.h>
>  > 
>  > size_t iconv(iconv_t cd, char **restrict inbuf,
>  > size_t *restrict inbytesleft, char **restrict outbuf,
>  > size_t *restrict outbytesleft);
> 
> Uh, I have no idea what you're getting at.
> 

I'm not familiar with opensolaris development.. I got an example:

#ifdef _XPG6
extern size_t	iconv(iconv_t, char **_RESTRICT_KYWD,
		size_t *_RESTRICT_KYWD, char **_RESTRICT_KYWD,
		size_t *_RESTRICT_KYWD);
#else
extern size_t	iconv(iconv_t, const char **_RESTRICT_KYWD,
		size_t *_RESTRICT_KYWD, char **_RESTRICT_KYWD,
		size_t *_RESTRICT_KYWD);
#endif

--
https://github.com/illumos/illumos-gate/blob/5a4ef21a18dfdc65328821a265582d03e85a97c9/usr/src/head/iconv.h


Assuming that the POSIX version has been already proposed as the default
one, how about:

#if defined(_NETBSD_SOURCE) && defined(_CONSTIFIED_ICONV)
size_t  iconv(iconv_t, const char ** __restrict,
                     size_t * __restrict, char ** __restrict,
                     size_t * __restrict);
#else
size_t  iconv(iconv_t, const char ** __restrict,
                     size_t * __restrict, char ** __restrict,
                     size_t * __restrict);
#endif

It will work for all c(89+)/c++(98+)/objc/.. compilers.

With that we could build software with additional CPPFLAGS defines when
needed.

Next step is to detect what fails to build in pkgsrc and adjust it
accordingly.