[Speex-dev] speex-1.2rc1 breaks ABI on OS X

[Hanspeter Niederstrasser]

On 8/2/10 9:17 AM, Jean-Marc Valin wrote:
> The part of the ABI that changed was never actually frozen to begin with. The
> stable part of the ABI (i.e. the codec part) is still the same as it was back
> in 1.0.
>
>      Jean-Marc

Thanks for the reply.  The problem is that during compilation, Darwin's 
linker marks which linked library provides each symbol (determined by 
the install name) and at runtime, dyld only searches that library for 
that symbol.

So now, something that linked to the old prebeta3 libspeex.1.dylib and 
needs, for example _speex_echo_cancel, will fail when the new postbeta3 
libspeex.1.dylib is present.  It will not look for it in 
libspeexdsp.1.dylib.  So now, if one package was built against the old 
speex and a new package is built against the new speex, the new speex 
must first be placed into some random dir like $PREFIX/lib/speex-b3 to 
prevent a filename collision.

 From what I understand of libtool versioning, any time an interface is 
removed, the install name (Darwin's soname) needs to be bumped (via 
-version_info flag in Makefile.am, or updating CURRENT or some similar 
method) in order to maintain portability.  I now understand that the ABI 
for those things wasn't frozen, but those symbols were available and 
things could have linked against them, and now they're missing.

Hanspeter