[LLVMdev] Name of the libraries + soname? 3.4.1 ?

[Tom Stellard]

On Mon, May 12, 2014 at 04:05:20PM +0200, Sylvestre Ledru wrote:
> On 12/05/2014 15:22, Tom Stellard wrote:
> > On Mon, May 12, 2014 at 08:41:36AM +0200, Sylvestre Ledru wrote:
> >> Hello,
> >>
> >> With the release of 3.4.1, the LLVM library has been renamed from
> >> libLLVM-3.4.so to libLLVM-3.4.1.so. In parallel, the soname has been
> >> updated to
> >> reflect this change.
> >>
> >> AFAIK, we kept the ABI compatible from 3.4 to 3.4.1. So, is there any
> >> reason for doing it?
> >> This caused some breakages in Debian (basically, breaking some X because
> >> of mesa could not
> >> link against LLVM due to the new soname).
> >> I noticed that we did the same with 3.5.
> >>
> >> I am not sure to understand what was wrong with the X.Y naming schema.
> > 
> > The library was renamed, but a libLLVM-3.4.so symlink was added to point
> > to libLLVM-3.4.1.so, so I don't think anything should break.
> Yes but the (distro?) tools relies on the soname for linking and the
> soname was updated.

Is soname an attribute that is stored somewhere within the shared library, or does
it refer to the name of the shared object file?

-Tom

> The link could not be done correctly. See:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=747701
> AFAIK, this change in the soname was not intentional.
> It is done in tools/llvm-shlib/Makefile
> LIBRARYNAME = LLVM-$(LLVMVersion)
> 
> Here, we should have done the opposite:
> * build libLLVM-3.4.so with libLLVM-3.4.so as soname
> * link libLLVM-3.4.so to libLLVM-3.4.1.so
> 
> > The rationale behind adding the patch level to the soname was to allow
> > applications to link against a specific LLVM point release.
> OK but it is clearly not the expected behavior from the distro POV. We
> expect the soname to remain the same if no changes in the ABI are done.
> Otherwise, we would have to rebuild all packages depending on libllvm
> just to fix that (instead, I hacked the build system to force
> libLLVM-3.4.so as soname).
> 
> Hoping I am clear here :)
> 
> Cheers,
> Sylvestre
> 
>