Shared library linked with static library: relocation error

Question

I would like to create a shared library with gfortran, linking it with the static version of libgfortran for portability reasons. Unfortunately, I don't manage to link the different objects appropriately. I have already found some posts addressing a similar issue, but I could not figure out how to fix the problem.

My source files are all compiled with the -fPIC flag. When I try to link the objects with the flags -shared and -static-libgfortran, I get the following error message:

gfortran -shared -static-libgfortran file1.o file2.o file3.o -o "mynewlib.so"
/usr/bin/ld: ../lib64/libgfortran.a(error.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC
../lib64/libgfortran.a: could not read symbols: Bad value
collect2: ld returned 1 exit status

I am using gfortran 4.6.3, that I compiled from scratch on my server. The installation ran smoothly and I did not change the standard configuration. I found on old posts that the compiler should be configured with --with-pic, but this flag is not mentioned in the GCC manual.

Does the problem come from the compiler or from the way I am trying to link the different objects? Any idea how I can fix this?

Thank you very much in advance for your help!

Haruspicy

Answer 1

The libgfortran, when you use the static version, is not compiled with the -fPIC flag (so it does not contain position indenpendent code).

Hence you cannot link libfgortran (statically) to your shared object.

I suggest you to package your library properly (e.g. as a .deb file for Debian or Ubuntu) and to add gfortran to the dependencies of your package.

Plectron

That was my guess, but how to get a version of libgfortran compiled with -fPIC? – Haruspicy

You might consider compiling GCC from its source code, and tweaking manually some flags (perhaps with ../gcc-4.7/configure CFLAGS='-fPIC' ....) but I really believe it is not worth the effort. – Plectron

More details on my problem: I am sharing this library on a server where a very old version of GCC is installed, which is too old to compile my code. I just installed a more recent version of GCC to solve this problem, but then my colleagues would also have to have access to the shared version of libgfortran. I thought it would be easier to have a self-contained shared library. Would you rather not do that? What's the alternative? Sharing libgfortran with them as well? – Haruspicy

Share the entire GCC 4.7 compiler suite with your colleagues. Ask help from, and tell about this issue, your sysadmin. – Plectron