[LLVMdev] global question

[Jean-Daniel Dupas]

Le 7 mars 09 à 20:10, John Regehr a écrit :

>> Please correct me if I'm wrong, but how can the compiler know, that  
>> x is not
>> initialized in another file which defines x as extern? It can only be
>> sure, when x is declared static.
>
> I don't think you can attach an initializer to an extern except at the
> point where the variable is defined.  But since x is defined here,  
> there
> would then be two definitions of x, a link-time error.
>

FWIW

-------- main.c ----------
#include <stdio.h>

int x;

int main(int arcg, char **argv) {
	fprintf(stderr, "x is: %d\n", x);
	return 0;
}


---------- init.c ---------
extern int x;

__attribute__((constructor))
static void __initialize() {
	x = 12;
}


[MacBook:~/Desktop]% gcc -c init.c
[MacBook:~/Desktop]% gcc -c main.c
[MacBook:~/Desktop]% gcc -o test init.o main.o
[MacBook:~/Desktop]% ./test
x is: 12


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