How, when, where to set script variables of libtool? (e.g. hardcode_minus_L)

Long story short: I worked on relative rpath linking with this script (that uses automake, autoconf, libtool). The problem is that the final rpath/runpath entry in the binary executable or so file still has the absolute path:

it turned out libtool is configured by default like this with hardcode_libdir_flag_spec to include any -L value if it's set in LDFLAGS

The only question remains: how and at which point (what's the proper way) can I set other libtool variables, like hardcode_minus_L. (I've searched for it on the net, but I couldn't find anything.)

I tried to do the following:

after configure is called I tried to replace the value of the variable with sed in libtool file (in the proper directory): it worked but when make is called it overwrote the whole libtool file again (it was regenerated)

Note, that 2 binary files are effected by this, entry for rpath/runpath with objdump -p:

libcurl.so : RUNPATH /home/user1/lib/rtorrent-0.9.7-1.5.3/lib:$ORIGIN/../lib
rtorrent : RUNPATH $ORIGIN/../lib:/home/user1/lib/rtorrent-0.9.7-1.5.3/lib

Thanks

Solution

It turned out it's fairly easy to modify these variables in configure.ac, no need for sed - after fiddling around and taking a look into the generated scripts. The only thing can be confusing that these variables can be applied to tags defined in the given project.

E.g. to change hardcode_libdir_flag_spec to an empty value in rtorrent project (means it will break compilation), you would insert into configure.ac:

_LT_TAGVAR(hardcode_libdir_flag_spec, )=""
_LT_TAGVAR(hardcode_libdir_flag_spec, CXX)=""
_LT_TAGVAR(hardcode_minus_L, )=yes
_LT_TAGVAR(hardcode_minus_L, CXX)=yes

The 2nd parameter is the tag or default tag if it's empty.