Based on this SO post I want to create software with gcc which uses mixed language source code, e.g. C and Fortran. While the linking of the generated object files works fine, the linker gives me the following error if I use a static or shared library instead of the object file:
/usr/bin/ld: /tmp/ccdqJ6hY.o: in function `MAIN__':
hello.f90:(.text+0x76): undefined reference to `fun'
collect2: error: ld returned 1 exit status
This is my C library source code file fun.c:
#include <stdio.h>
void fun(void) {
printf("Hello from C function.\n");
}
This is my Fortran source code hello.f90:
program hello
print *, "Hello from Fortran program."
call fun()
end
This is my build script:
#! /bin/sh
#
gcc -c fun.c # Create object file of C library
ar r libfun.a fun.o # Create static C library
gcc -shared -o libfun.so fun.o # Create shared/dynamic linked C library
#
gfortran -fno-underscoring -o hello1 fun.o hello.f90 # This works.
#
gfortran -fno-underscoring -o hello2 -L. -Wl,-rpath=`pwd` -lfun hello.f90 # This fails.
#
gfortran -fno-underscoring -o hello3 -L. libfun.a hello.f90 # This fails.
The symbol name fun is fine in the libraries as indicated by nm:
$ nm libfun.a
fun.o:
0000000000000000 T fun
I'm using gcc version gcc (Debian 10.2.1-6) 10.2.1 20210110 on Debian GNU/Linux 11 (bullseye).
I suppose that something with my gcc configuration might be broken, but I have no glue, what.
Could you give me any advice, please?
