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Libtool

5.2 Using Automake with libtool

Libtool library support is implemented under the `LTLIBRARIES' primary.

Here are some samples from the Automake `Makefile.am' in the libtool distribution's `demo' subdirectory.

First, to link a program against a libtool library, just use the `program_LDADD' variable:

bin_PROGRAMS = hell hell.debug # Build hell from main.c and libhello.la hell_SOURCES = main.c hell_LDADD = libhello.la # Create an easier-to-debug version of hell. hell_debug_SOURCES = main.c hell_debug_LDADD = libhello.la hell_debug_LDFLAGS = -static

The flags `-dlopen' or `-dlpreopen' (see section 4.2 Link mode) would fit better in the program_LDADD variable. Unfortunately, GNU automake, up to release 1.4, doesn't accept these flags in a program_LDADD variable, so you have the following alternatives:

• add them to program_LDFLAGS, and list the libraries in program_DEPENDENCIES, then wait for a release of GNU automake that accepts these flags where they belong;

• surround the flags between quotes, but then you must set program_DEPENDENCIES too:

  program_LDADD = "-dlopen" libfoo.la program_DEPENDENCIES = libfoo.la

• set and `AC_SUBST' variables DLOPEN and DLPREOPEN in `configure.in' and use `@DLOPEN@' and `@DLPREOPEN@' as replacements for the explicit flags `-dlopen' and `-dlpreopen' in `program_LDADD'. Automake will discard `AC_SUBST'ed variables from dependencies, so it will behave exactly as we expect it to behave when it accepts these flags in `program_LDADD'. But hey!, this is ugly!

You may use the `program_LDFLAGS' variable to stuff in any flags you want to pass to libtool while linking `program' (such as `-static' to avoid linking uninstalled shared libtool libraries).

Building a libtool library is almost as trivial... note the use of `libhello_la_LDFLAGS' to pass the `-version-info' (see section 6. Library interface versions) option to libtool:

# Build a libtool library, libhello.la for installation in libdir. lib_LTLIBRARIES = libhello.la libhello_la_SOURCES = hello.c foo.c libhello_la_LDFLAGS = -version-info 3:12:1

The `-rpath' option is passed automatically by Automake (except for libraries listed as noinst_LTLIBRARIES), so you should not specify it.

See section `The Automake Manual' in The Automake Manual, for more information.