Re: [fluid-dev] SONAME Bump?

[David Henningsson]

On 08/06/2011 02:13 PM, Pedro Lopez-Cabanillas wrote:
> On Saturday 06 August 2011, David Henningsson wrote:
> > As reported in ticket #98, FluidSynth 1.1.4 dropped one symbol. However,
> > this symbol (fluid_defsfont_get_sample) is not part of the public API,
> > so no programs should use it anyway.
> >
> > I don't know how much of a big deal this is, really. Can you help me
> > determine that, and the proper action for it?
>
> It is a bug, and should be resolved. Not a big concern, because as you noticed 
> it is not part of the public API.

Ok.

> > Is it something that alone calls for a new release (1.1.5) or can we
> > just update svn? What implications does bumping the SONAME have?
>
> Changing the SONAME because this bug is too much a burden for everybody.

Sorry, I'm not following: what burden would changing the SONAME be - is 
that just recompiling everything depending on libfluidsynth, or what?

> My suggestion is to restore the removed symbol with a dummy function body, and 
> release 1.1.5

Ok, I can add a dummy function body. Let's wait a week or two to see if 
more showstoppers show up before making another release.

> > IMO, the ideal would be if we could tell gcc to stop exporting all
> > symbols that are not part of the public API. Then we would get rid of
> > this problem altogether. Is that possible?
>
> Yes, this is possible. But this is a task for the next major release, and of 
> course it requires changing the SONAME anyway.
>
> Technically, we need to take into account all platforms and compilers. For the 
> GCC compiler, we have several tools:
> * gcc arguments CFLAGS=-fvisibility=hidden
>         
> http://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fvisibility-2198
>         Source changes. Either:
>         * function attributes: 
> http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
>                 * dllimport and dllexport attributes for Windows platform (we 
> already do this in the macro FLUIDSYNTH_API)
>                 * visibility attribute for ELF platforms
> http://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html#index-g_t_0040code_007bvisibility_007d-attribute-2547

Thanks for the pointers. As the FLUIDSYNTH_API is already in place, if 
we could make that evaluate to something like __attribute__ ((visibility 
("default"))) on gcc platform, that would be the simplest way of solving 
this problem?

>         * visibility #pragma: 
> http://gcc.gnu.org/onlinedocs/gcc/Visibility-Pragmas.html
> * we can also include a linker version script as a complement
> http://sca.uwaterloo.ca/coldfire/gcc-doc/docs/ld_25.html

Hmm, with those options I think that we need to update in one more place 
every time we change the public API. That makes it possible to forget 
one of the places.

// David