Difference between --static and -static LD_FLAGS in Makefile.am

Question

I am working on debugging a library linking problem and i came across something i didnot expect. Here is the issue. I am using build tools to generate my Makefile and so i only have to write Makefile.am. The eventual goal is to build a shared library( srv.so ). There are some libs that i want to link statically so i want to use the "static" flag to LD. My Makefile.am has LD_FLAGS like this

srv_la_LDFLAGS= -module -avoid-version

Now when i add the "static" flags it turns our there are 2 seperate interpretations of it

1st

srv_la_LDFLAGS= -module -avoid-version -static /path/to/lib.a

2nd

srv_elastica_la_LDFLAGS= -module -avoid-version --static /path/to/lib.a

Notice the difference between --static and -static .

The 1st one produces a linker line which run ar and attempts to produce srv.a instead of srv.so

/bin/bash ../../libtool --tag=CC   --mode=link gcc -I../../include/  
-Wno-unused-label     -DMONGO_HAVE_STDINT   -g -O2 -Wall -D_REENTRANT -g -O2 -Wall 
-DCI_BUILD_MODULE -I/usr/local /c_icap/include/c_icap -module -avoid-version -z defs 
-static /usr/local/lib/libmongoc.a  -o srv.la -rpath /usr/local/lib/c_icap_modules 
 srv_la-srv.lo -lrt -lcre2 -lre2 -lcurl -lpthread -lbson 

*** Warning: Linking the shared library srv_elastica.la against the
*** static library /usr/local/lib/libmongoc.a is not portable!
libtool: link: ar cru .libs/srv.a /usr/loc/lib/libmongoc.a                     
.libs/srv_la-srv.o

Whereas the 2nd one produces the correct linker line( -shared ) to output srv.so

/bin/bash ../../libtool --tag=CC   --mode=link gcc -I../../include/ -Wno-unused-label  
-DMONGO_HAVE_STDINT   -g -O2 -Wall -D_REENTRANT -g -O2 -Wall -DCI_BUILD_MODULE -I/usr
/local/c_icap/include/c_icap -module -avoid-version -z defs --static /usr/local
/lib/libmongoc.a  -o srv.la -rpath /usr/local/lib/c_icap_modules srv_la-srv.lo
-lrt -lcre2 -lre2 -lcurl -lpthread -lbson 

*** Warning: Linking the shared library srv_elastica.la against the
*** static library /usr/local/lib/libmongoc.a is not portable!
libtool: link: gcc -shared  -fPIC -DPIC  .libs/srv_la-srv.o
/usr/local/lib/libmongoc.a -lrt -lcre2 -lre2 /usr/lib/x86_64-linux-gnu/libcurl.so 
-lpthread -lbson  -O2 -O2   -Wl,-soname -Wl,srv.so -o .libs/srv.so

This is kind of strange.There is nothing mentioned on manpage of ld of this sort. Any help?

Answer 1

Test library requests static library from your build test library.it should define in Makefile.am follow as

srv_elastica_la_LDFLAGS= -module -avoid-version --static -L/path/to/lib_test_name -llib_test_name

In case you declare -static flag in name_LDFLAGS. We define -static in order to link the dynamic libraries on project.