Re: ld-output-def

[Ralf Wildenhues]

* Simon Josefsson wrote on Wed, Apr 01, 2009 at 06:50:07AM CEST:
> Bruno Haible <address@hidden> writes:
> > Your documented example looks like this:
> >
> >> +if HAVE_LD_OUTPUT_DEF
> >> +libfoo_la_LDFLAGS += -Wl,--output-def,libfoo-$(SOVERSION).def
> >> +defexecdir = $(bindir)
> >> +defexec_DATA = libfoo-$(SOVERSION).def
> >> +DISTCLEANFILES += $(defexec_DATA)
> >> +endif
> >
> > What is $(SOVERSION) ? As I understand it, libfoo-$(SOVERSION).def should
> > match the basename of libfoo-$(SOVERSION).dll, right? But that basename is
> > determined by libtool from the L:T:V triple that gets passed as
> > -version-info argument, in an undocumented (platform dependent) way.
> 
> I forgot this aspect.  The application needs to compute the SOVERSION
> field from the values passed to libtool.  Assuming the projects uses:
> 
> AC_SUBST(LT_CURRENT, 1)
> AC_SUBST(LT_REVISION, 1)
> AC_SUBST(LT_AGE, 0)
> ...
> libgss_la_LDFLAGS = -no-undefined \
>       -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE)
> 
> It can compute the SOVERSION value as follows:
> 
> SOVERSION=`expr ${LT_CURRENT} - ${LT_AGE}`
> AC_SUBST(SOVERSION)
> 
> I'll include this in an updated version of the patch.

But this requires the user to know the particular version computation
for this one system.  Worse even, the generic name `SOVERSION' easily
implies to the naive user that this version holds for all systems this
package may be built upon.  That can't be sensible.

> > Right? Then, the --output-def functionality should be available
> > through libtool. We are not supposed to define and update manually an
> > SOVERSION macro that is actually the result of some computations done by
> > libtool.
> 
> DEF files are only relevant for windows targets, so I don't see any
> point in having this functionality in libtool?

I don't understand this argument.  AIUI you won't be using this
functionality without libtool at all anyway, right?  But even if,
the above is an argument *for* including this functionality in libtool.

I think all the functionality you need is contained in the
pr-msvc-support branch of git Libtool.  Can you check whether that is
sufficient for you?

Thanks,
Ralf