readline with shared libraries on Mac OS X/Darwin

[David R. Morrison]

Hello.  I'm one of the developers in the Fink project, which packages Unix
software for Mac OS X/Darwin.

We've noticed a problem with the darwin|macosx "stanza" in the shobj-conf
file in readline.  In Darwin, the shared library command requires a bunch
of flags which are unknown on ELF and other systems.  The flag giving
trouble is Darwin's -install_name flag.

Whoever wrote this stanza (and it may well have been Fink's founder, chrisp,
who is no longer with the project), wrote
  -install_name $(libdir)/$@
and when this is actually used (in the current version, say), $@ expands to
libreadline.4.3.dylib or libhistory.4.3.dylib.  However, what we need it to
expand to is libreadline.4.dylib or libhistory.4.dylib.  In other words, it
should show the filename with only the major version number present, not
the minor version number.

(You'll notice other differences from ELF, like our suffix coming after the
number instead of before.)

Does anyone have suggestions for how this can be implemented?  I can't find
a similar construction in other stanzas, and I hesitate to hack away on it
without advice since I don't know where and how SHLIB_XLDFLAGS is used
in the code.

(We've had to add "ln -s libreadline.4.3.dylib libreadline.4.2.dylib" to our
Fink package to get backwards compatibility in the recent upgrade; this
wouldn't be necessary if we had the .4.dylib construction instead.)

  Thanks,
  Dave