Re: [bug-gettext] Linking problem using mingw-w64

[B. Scott Michel]

On 09.03.2012 03:39, Marcel Wysocki wrote:

> can be fixed using this patch:
>
> http://code.google.com/p/mingw-w64-dgn/source/browse/trunk/patch/gettext-0.18.x-w64.patch
> no idea if its a valid fix or just a workaround tho.

It looks like a reasonable workaround. There is a more fundamental 
problem to address, if you've grep-ed your code for warnings. For 
example, this kind of code generates a warning:

extern __dllimport int exit_failure;
int exit_failure = 1;

GCC 4.6.x and 4.7.x both expect consistency with declaration 
attributes, despite the fact that the warnings are fairly harmless. 
Unless a gettext maintainer says otherwise, I'm inclined to rework the 
Makefile.am and header files so that the suggestions from the "GCC 
visibility" pages are implemented properly. That is, using libintl as an 
example:

- Change "DLL_VARIABLE" to something more meaningful, such as 
"LIBINTL_VISIBILITY".

- config.h.in contains something like this:

#if HAVE_VISIBILITY && COMPILING_ON_WINDOWS_PLATFORM
#  if BUILDING_LIBINTL
#    define LIBINTL_VISIBILITY __declspec(dllexport)
#  else
#    define LIBINTL_VISIBILITY __declspec(dllimport)
#  endif
#elif defined HAVE_VISIBILITY && BUILDING_LIBINTL
#define LIBINTL_VISIBILITY __attribute__((__visiblity__("default")))
#else
#define LIBINTL_VISIBILITY
#endif

- Eliminate the woe32dll "-export.c" files, since the declaration 
attribute takes care of the problem.

- Introduce an install pre-hook that replaces "LIBINTL_VISIBLE" with 
"__declspec(dllimport)" when the header files are installed on win32 and 
win64.

Yes, I know it will probably break something on FreeBSD or Linux, but 
the result will be a more robust code base and allow for future function 
visibility modifications for ELF DSOs.


-scooter

"GCC visibility" page: 
http://www.gnu.org/software/gnulib/manual/html_node/Exported-Symbols-of-Shared-Libraries.html