Make static libtool library with no source files

Question

Using autotools and libtool, I need to merge several libraries in subdirectories into a bigger static library in toplevel directory. Here is schema:

# src/Makefile.am

ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS} -I m4                                                                                                                               
AUTOMAKE_OPTIONS = subdir-objects                                                                                                                                      

SUBDIRS = foo bar .                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

noinst_LTLIBRARIES = libbig.la                                                                                                                     

libbig_la_LIBADD = \                                                                                                                               
    foo/libfoo.la \
    foo/libbar.la                                                                                                                              

In sub-directories:

# src/foo/Makefile.am

ACLOCAL_AMFLAGS = ${ACLOCAL_FLAGS} -I m4                                                                                                                               

noinst_LTLIBRARIES = libfoo.la                                                                                                                     

libbig_la_SOURCES = \                                                                                                                               
    foo.cpp \
    foo_ji.cpp 

It says no rule to make target libbig.la. Is it possible to make a library (static or shared) using no source files?

Answer 1

It needs to read libfoo_la_SOURCES and libbig_la_SOURCES and libbig_la_LIBADD