Re: Use a variable before it's declaration

Rock Lee <rocklee_104@outlook.com> writes:

...

Hi, all: Here is a snippet of linux-v3.4 which drives me crazy. Because init_task hasn't been declared yet when init_thread_union is initializing. Why is there no compiling error? Any hint would be helpful.

union thread_union init_thread_union __init_task_data =

{ INIT_THREAD_INFO(init_task) };

/*

* Initial task structure.

*

* All other task structs will be allocated on slabs in fork.c

*/

struct task_struct init_task = INIT_TASK(init_task);

Because init_task is declared "extern" in linux/sched.h

Bjørn

I do something like that: extern int b; int a = b + 10; int b = 20; int main(void) { return 0; } No doubt, compiling error. -- Rock Lee