I am attempting to link a thin archive that combines two archive libraries to a C program.
I constructed two simple hello world functions and built an archive with the commands:
ar rcs lib1.a lib1.o
ar rcs lib2.a lib2.o
The two archives are then merged using a thin-archive:
ar rcsT all_lib.a lib1.a lib2.a
and then compiled with gcc:
gcc main.o all_lib.a -o hello
I end up with a error message saying:
ld: warning: ignoring file all_lib.a, file was built for unsupported file format which is not the architecture being linked (x86_64)
Undefined symbols for architecture x86_64: "_func1", referenced from: _main in main.o "_func2", referenced from: _main in main.o ld: symbol(s) not found for architecture x86_64
If I attempt to link main.o with lib1.a and lib2.a directly, everything works.
I am using gcc (MacPorts gcc46 4.6.3_3) 4.6.3 and GNU ar (GNU Binutils) 2.21 on Mac OSX 10.6.8.
Makefile
test1: main.o lib1.o lib2.o
gcc main.o lib1.a lib2.a -o hello
test2: main.o combine
gcc main.o all_lib.a -o hello
lib1.o: lib1.c
gcc -c lib1.c
ar rcs lib1.a lib1.o
lib2.o: lib2.c
gcc -c lib2.c
ar rcs lib2.a lib2.o
combine: lib1.o lib2.o
ar rcsT all_lib.a lib1.a lib2.a
main.o: main.c
gcc -c main.c
clean:
rm -rf *.o *.a hello
main.c
#include<stdio.h>
#include "lib1.h"
#include "lib2.h"
main()
{
printf("Hello World\n");
func1();
func2();
}
lib1.h
#include<stdio.h>
void func1();
lib2.h
#include<stdio.h>
void func2();
lib1.c
#include "lib1.h"
void func1()
{
printf("Hello World 1\n");
}
lib2.c
#include "lib2.h"
void func2()
{
printf("Hello World 2\n");
}