support building sassc with shared libsass library about sassc

[craigbarnes]

I added the shared target to the libsass Makefile a while back to make it easier to package for Fedora. I never got around to submitting one for sassc, since it's so easy to manually build the single file. I'll make a patch soon unless someone beats me to it but I'm guessing the main authors are quite content with static linking.

[akhleung]

We're currently happy with static linking, but if you have a working patch for linking against a shared libsass, please make a pull request!

[idupree]

If you use the autotools build systems for libsass and sassc, then sassc is already built against shared libsass. On my Arch Linux:

% ldd /usr/bin/sassc
        linux-vdso.so.1 (0x00007fffa3944000)
        libsass.so.0 => /usr/lib/libsass.so.0 (0x00007f75cfc8a000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007f75cf8e7000)
        libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x00007f75cf5d8000)
        libm.so.6 => /usr/lib/libm.so.6 (0x00007f75cf2d3000)
        libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007f75cf0bd000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f75d0001000)

I didn't write the build systems, I only packaged them for Archlinux (libsass, sassc). So I don't know why there are two buildsystems (namely: plain old Makefiles; and autotools that overwrites the plain old Makefiles if you run ./configure [1]). Currently the autotools build system is most suitable for distro packaging, and the Makefile build system is most convenient for development of libsass/sassc.

[1] If using a git checkout, first run something like autoreconf -i to generate the configure script.

[craigbarnes]

@idupree Unless I'm mistaken, it seems the libsass API and ABI have changed quite a bit without any corresponding soname version bumps. The autotools build does seem best, but I'm not so sure that any dynamically linked build is suitable for distro packaging without proper versioning.

[mgreter]

Actually there were some commits recently that have added basic test if dynamic linking is working.
The version for libtool is defined in Makefile.am

libsass_la_LDFLAGS = -no-undefined -version-info 0:0:0

This was pretty much just prepared for once libsass wants to ship stable libraries.
I guess it is currently still moving to fast to consider this, but IMO we're getting there.

I actually have refactored the c interface quite heavily on a local branch to get the api/abi more stable in this perspective. Will probably create a PR soon to get this going. This could finally close the oldest standing issue reported for libsass.

[mgreter]

Sassc can now link libsass dynamically:
https://travis-ci.org/sass/sassc/builds/43364566