Re: [bug-gnulib] new module lib-ignore; new section build_lib in MODULES.html

[Bruno Haible]

Paul Eggert wrote:
> If a package like that defines several programs,
> only some of which call clock_gettime, then the maintainer will have
> to do something like this (this is an extract from
> coreutils/src/Makefile.am):
>
> pr_LDADD = $(LDADD) $(LIB_CLOCK_GETTIME)
> shred_LDADD = $(LDADD) $(LIB_GETHRXTIME) $(LIB_FDATASYNC)
> sort_LDADD = $(LDADD) $(POW_LIB) $(LIB_GETHRXTIME)
> ...
>
> where each program is carefully linked to each optionally-available
> library it might use.

Yes, that's the state-of-the-art technique. It's tedious but reliable.

> This sort of cataloging is error-prone and a pain to maintain.  It
> should be automated, and -zignore does the automation.

Is -zignore fully portable? If you find only a single platform where
-zignore's functionality does not exist, then you need to go back to the
explicit list of potential dependencies.

>       if test "$gl_ldd_output0"; then

The autoconf manual recommends   test -n "$gl_ldd_output0"   here.

>         test "$gl_ldd_output0" != "$gl_ldd_output1" then

I'm not sure that all 'ldd' variants will keep the output the same when
the set of dependent libraries has not changed. Some also include hexadecimal
addresses in the output, I think.

Bruno