Why Autotools Ignores Installed Static Library? - static-linking

Question

I have installed ROHC library (http://rohc-lib.org) using following commands during installation:
autoreconf -if
./configure --enable-static=yes --enable-shared=no --disable-shared --prefix=/usr
make
make install
It successfully installed static (and only static) libraries in /usr/lib directory. It contains librohc.a and librohc.la and no shared-library (i.e. librohc.so*).
I am trying to link this library with OpenVPN. I added following lines in configure.ac of OpenVPN:
AC_CHECK_HEADERS(
[rohc/rohc.h rohc/rohc_comp.h rohc/rohc_decomp.h],
,
[AC_MSG_ERROR([ROHC headers not found])]
)
AC_CHECK_LIB(
[rohc],
[rohc_compress4],
,
[AC_MSG_ERROR([ROHC library not found])]
)
But when I run make in OpenVPN source directory, I get the following error:
/bin/sh ../../libtool --tag=CC --mode=link gcc -DPLUGIN_LIBDIR=\"/usr/local/lib/openvpn/plugins\" -Wall -Wno-unused-parameter -Wno-unused-function -g -O2 -std=c99 -lrt -o openvpn argv.o base64.o buffer.o clinat.o comp.o compstub.o comp-lz4.o crypto.o crypto_openssl.o crypto_mbedtls.o dhcp.o error.o event.o fdmisc.o forward.o fragment.o gremlin.o helper.o httpdigest.o lladdr.o init.o interval.o list.o lzo.o manage.o mbuf.o misc.o platform.o console.o console_builtin.o console_systemd.o mroute.o mss.o mstats.o mtcp.o mtu.o mudp.o multi.o ntlm.o occ.o pkcs11.o pkcs11_openssl.o pkcs11_mbedtls.o openvpn.o options.o otime.o packet_id.o perf.o pf.o ping.o plugin.o pool.o proto.o proxy.o ps.o push.o reliable.o route.o schedule.o session_id.o shaper.o sig.o socket.o socks.o ssl.o ssl_openssl.o ssl_mbedtls.o ssl_verify.o ssl_verify_openssl.o ssl_verify_mbedtls.o status.o tls_crypt.o tun.o win32.o rohc.o trunk.o cryptoapi.o ../../src/compat/libcompat.la -lnsl -lresolv -llzo2 -llz4 -lssl -lcrypto -ldl -lrohc
libtool: link: gcc -DPLUGIN_LIBDIR=\"/usr/local/lib/openvpn/plugins\" -Wall -Wno-unused-parameter -Wno-unused-function -g -O2 -std=c99 -o openvpn argv.o base64.o buffer.o clinat.o comp.o compstub.o comp-lz4.o crypto.o crypto_openssl.o crypto_mbedtls.o dhcp.o error.o event.o fdmisc.o forward.o fragment.o gremlin.o helper.o httpdigest.o lladdr.o init.o interval.o list.o lzo.o manage.o mbuf.o misc.o platform.o console.o console_builtin.o console_systemd.o mroute.o mss.o mstats.o mtcp.o mtu.o mudp.o multi.o ntlm.o occ.o pkcs11.o pkcs11_openssl.o pkcs11_mbedtls.o openvpn.o options.o otime.o packet_id.o perf.o pf.o ping.o plugin.o pool.o proto.o proxy.o ps.o push.o reliable.o route.o schedule.o session_id.o shaper.o sig.o socket.o socks.o ssl.o ssl_openssl.o ssl_mbedtls.o ssl_verify.o ssl_verify_openssl.o ssl_verify_mbedtls.o status.o tls_crypt.o tun.o win32.o rohc.o trunk.o cryptoapi.o ../../src/compat/.libs/libcompat.a -lrt -lnsl -lresolv -llzo2 -llz4 -lssl -lcrypto -ldl /usr/lib/librohc.so
gcc: /usr/lib/librohc.so: No such file or directory
Yes, /usr/lib/librohc.so does not exist, but /usr/lib/librohc.a exists. Why is it not linking with the static library /usr/lib/librohc.a at absence of .so ?
You may ask me why I am not installing shared libs of ROHC; answer is that I want to force static linking with ROHC, and when it is done I will uninstall ROHC libs.
If someone could show me how to do this static linking without installing ROHC first (like adding dependency to configure.ac or Makefile.am of OpenVPN), it would be better for me.
Note that, both OpenVPN and ROHC library require autotools.

Answer 1

I specified --libdir=/usr/lib64 with ./configure of ROHC library and finally the build system used the static library librohc.a when linking with OpenVPN. I installed ROHC with:
autoreconf -if
./configure --enable-static --disable-shared --prefix=/usr --libdir=/usr/lib64
make
make install
Now it installs the library as /usr/lib64/librohc.a and Compilation of OpenVPN successfully finds and links to it.
And surely, it took place in a 64 bit machine (CentOS 6). In a 32 bit environment (OpenWrt in a 32-bit MIPS router) where there is nothing like /usr/lib64, the problem in the question does not take place.