Re: Alternate SONAME values

[Ralf Wildenhues]

Hi Keith,

* Keith Packard wrote on Fri, Jul 08, 2005 at 06:59:10AM CEST:
> On Fri, 2005-07-08 at 09:24 +0530, Ganesan Rajagopal wrote:
> 
> > But libXaw.so.<major_number> is the default behaviour for libtool.  Are you
> > using -release instead of -version-info or -version-number? I think
> > -version-number will give you exactly what you need.
> 
> I want the SONAME to be libXaw.so.6, but the filename to be libXaw6.la,
> libXaw6.so.6.0.1, libXaw6.so.6 and libXaw6.so
> 
> And, yes, I'm already using -version-number (which I added to libtool)
> as X has always used the same version number on all platforms (yes, this
> is bad, but I can't do anything about it).

I have thought a little bit about this, quite a bit of open questions
still, before I can allow myself an informed opinion about this.
(I'll freely admit that you probably know more about the topic than I
do.  :)

First, to stay with your GNU/Linux example, unless you also have
libXaw.so.6 as symlink, how will ld.so find your library (as installed
library; or alternatively as user-installed test version below $HOME)?

Second, have you tried this on a different system?  Especially for
  AIX (without runtime linking)
  Darwin
  w32 (cygwin/mingw)
I don't know off the head whether this could be made to work.

Next, what is the general rule for applications which may use libraries
that link against different Xaw major versions?  Here, big trouble may
ensue.  It sounds like you don't want to encourage this anyway, but I'm
not certain.  (Carrying this on and allowing other libs several major
versions installed, you may end up with libraries libfoo6-bar2-Xaw7,
since the dependent libraries have to carry over that versioning.)

Last, I do believe that if Libtool were to allow this, it might have to
adapt its deplib search algorithm as well, at least on some systems.
This in turn should avoid backwards-incompatibility (i.e., older libtool
versions not being able to link against the libs created by newer
libtool).  Haven't thought about this in detail yet, but I'd really like
to avoid breaking applications that depend on libXaw* and happen to use
(an older version of) libtool, if possible.

Cheers,
Ralf