pinctrl: sirf/atlas7: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this change:

"Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

---
 drivers/pinctrl/sirf/pinctrl-atlas7.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index b1a9611f46b3..50df9e084414 100644
@@ -352,7 +352,7 @@ struct atlas7_gpio_chip {
 	int nbank;
 	raw_spinlock_t lock;
 	struct gpio_chip chip;
-	struct atlas7_gpio_bank banks[0];
+	struct atlas7_gpio_bank banks[];
 };
 
 /**

2.25.0

Patch applied!

Yours,
Linus Walleij