Check undefined init_priority static object dependency

[Quuxplusone]

Bugzilla Link	PR20066
Status	NEW
Importance	P enhancement
Reported by	Albert Zeyer (ich@az2000.de)
Reported on	2014-06-17 09:15:45 -0700
Last modified on	2018-10-10 07:43:08 -0700
Version	unspecified
Hardware	PC All
CC	ganna@apple.com, llvm-bugs@lists.llvm.org
Fixed by commit(s)
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Example:

header.h:

extern int a;
extern int b;

a.cpp:

#include "header.h"
int a = 2;

b.cpp:

#include "header.h"
int b = a;

main.cpp:

#include <stdio.h>
#include "header.h"

__attribute__((constructor))
static void init() {
    printf("init: %i %i\n", a, b);
}

int main() {}

---

a and b will both get the same init_priority (I think it's
DEFAULT_INIT_PRIORITY = 65535), and thus it's not well defined whether a or b
is initialized first.

I would like to have a check, if the initialization of a global/static variable
depends on another global/static variable (int b = a), its init_priority must
be a  bigger value than of all its dependencies.

---

In case that you wont implement this feature in the (near) future, maybe you
can give some guidance about what I need to do to implement such a static check
myself.

[Quuxplusone]

Currently, the clang static analyzer does not have cross implementation file
analysis, so there is not enough infrastructure to implement this effectively.

Check out the initialization order checking with Address Sanitizer and see if
that is something you might be able to use instead:
http://clang.llvm.org/docs/AddressSanitizer.html

For more info, use cfe-dev mailing list.