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Re: [bug-gnu-libiconv] iconv.h differs on Mac OS X 10.4 and 10.5

From: Ryan Schmidt
Subject: Re: [bug-gnu-libiconv] iconv.h differs on Mac OS X 10.4 and 10.5
Date: Thu, 3 Jul 2008 00:45:23 -0500

On Jun 2, 2008, at 19:14, Bruno Haible wrote:

Ryan Schmidt wrote:

I have a problem with iconv.h from libiconv 1.12 and the
fact that it differs depending on whether it's installed on Mac OS X
10.4 or 10.5.

On Mac OS X 10.4 with Xcode 2.4.1 (or Xcode 2.5), and libiconv 1.12
installed by MacPorts, iconv.h defines the iconv() function this way:

extern size_t iconv (iconv_t cd, const char* * inbuf, size_t
*inbytesleft, char* * outbuf, size_t *outbytesleft);

On Mac OS X 10.5 with Xcode 3.0 (or Xcode 3.1 from iPhone SDK beta
6), the same version of libiconv defines the second parameter of iconv
() differently:

extern size_t iconv (iconv_t cd,  char* * inbuf, size_t *inbytesleft,
char* * outbuf, size_t *outbytesleft);

libiconv, installed from source, uses 'const' or not here, depending whether the system header uses 'const' or not. And in MacOS X 10.5, Apple changed their headers for POSIX compliance (so as to get the UNIX 2003 branding).
And POSIX happens to specify 'char **' for iconv's inbuf parameter.

See the diff between the 10.4 and 10.5 headers at the end of this mail.

This causes problems for software that wants to work on both Mac OS X
10.4 and 10.5. See:

cpp%2FPortfile%4037235&old=trunk%2Fdports%2Fdevel%2Fice-cpp% 2FPortfile



The developer of the pure language feels this is a bug in libiconv.

This incompatible change is under Apple's responsibility, since they changed
the system header.

You can blame libiconv for having used 'const' by default in the past, but
this is "corrected" in libiconv 1.12.

As a way out, the iconv.m4 macro from gnulib
detects the presence or absence of 'const' and defines ICONV_CONST
accordingly. So that you can cast the argument to (ICONV_CONST char **)
and be safe in all cases. It is documented here:
<http://www.gnu.org/software/gettext/manual/html_node/ AM_005fICONV.html>

Thanks for the tip! Pure now uses autoconf so it can use this macro to detect the proper way to call iconv.

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