Linking to sibling libtool library with recursive Automake

Question

I am building a shared library, and have a source tree structured like this:

Makefile.am
src/
    Makefile.am
    srcfile1.h
    srcfile1.cpp
    ...
thirdpaty/
    Makefile.am
    lib1/
        Makefile.am
        lib1.h
        lib1.cpp
        ...
    lib2/
        ...

I use recursive Automake since some of the third party libraries are distributed with their own Automake files. src/Makefile.am includes the usual libtool macros:

lib_LTLIBRARIES = libmylib.la 
libmylib_la_SOURCES = scrfile1.h srcfile1.cpp ...

How do I link the main library to the third party ones? The Autotools manual leads me to believe that the third party libraries needs to be built as libtool convenience libraries, so I have the following in thirdparty/lib1/Makefile.am:

noinst_LTLIBRARIES  = libthirdpaty1.la
libthirdpaty1_la_SOURCES = lib1.cpp lib1.h

And add the following in src/Makefile.am:

libmylib_la_LIBADD = $(top_buildir)/thirdparty/lib1/libthirdpaty1.la

My root Makefile.am holds the INCLUDES macro:

INCLUDES = -I$(top_builddir)/thirdparty

But building with this configuration gives me undefined symbol errors.

What is the correct way to structure this source code and link all the libraries together?

Answer 1

It turns out that that source layout and libtool usage were fine, but my root Makefile.am had the following macro:

SUBDIRS = src thirdparty

Which should have been

SUBDIRS = thirdparty src

Since the code in src/ referenced the code in thirdparty/, the thirdparty/ code needed to be built first. The SUBDIRS macro causes subfolders to be built in the order they are specified, from left to right.