[Zlib-devel] zlib 1.2.3.6 available for testing

[Török Edwin]

On 01/19/2010 02:47 PM, glennrp at comcast.net wrote:
> 1) >> IIRC we now have multiple versions of some functions (the libxml issue),
>   
>>> I'd like to see a way for getting rid of the old ones at compile time.
>>>       
>> Only one set of functions is compiled for a given build.
>>     
>
> See some recent discussion on png-mng-implement.
>
> It seems that now instead of building libfoo.so.0, libfoo.so.2, libfoo.so.4
> the linker no longer uses the final suffix.  Instead when you build
> libfoo.so, internally each symbol (function, global variable, etc.)
> gets a version symbol appended and they all go into the same library
>
>   You compile libfoo and it contains an entry point foo()
>   Somehow when you construct the shared library,
>
>   libfoo.so.1 contains entry points like
>     foo{0}()
>     foo{2}()
>     foo{4}()
>
> if I understand the png-mng implement discussion and gcc documentation
> correctly.  We aren't doing it that way with libpng, but some downstream
> distros might be.  I don't even know how the step of merging several
> versions into one library is done.  

See section 3.7 "Incompatible changes" in Ulrich Drepper's DSO howto:
http://people.redhat.com/drepper/dsohowto.pdf

Unfortunately that only works on Linux (compatible changes are also
supported on
Solaris's linker, but thats it).

Best regards,
--Edwin