Mac Forum / Programming / Mac Programming / May 2007

hello,

i'm having troubles with symbol resolution of variables when linking
to a static library. here's a simple setup that can be used reproduce
the issue:

---------------------------------------------------
~/mactest/tmp>cat one.c
int a;
~/mactest/tmp>cat two.c
#include<stdio.h>
extern int a;
void show(){printf("a is %d\n",a);}
~/mactest/tmp>cat main.c
int main(){show();}
~/mactest/tmp>make main
cc    -c -o main.o main.c
cc    -c -o one.o one.c
cc    -c -o two.o two.c
libtool -o liba.a one.o two.o
cc main.o -L. -la -o main
/usr/bin/ld: Undefined symbols:
_a
collect2: ld returned 1 exit status
make: *** [main] Error 1
---------------------------------------------------

the int 'a' is defined in one.o - and it is accessed inside two.o.
when i club the two object files together into a single static library
and link it with an executable the resolution fails, as seen above.
any clues? the "undefined symbols" error goes when i pass the "-
all_load" option. but i don't want to go that way, because "-all_load"
might load a lot of unwanted symbols.

thanks,