Zero-length arrays are deprecated and we are moving towards adopting
C99 flexible-array members, instead. So, replace zero-length arrays
declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
helper macro.

This helper allows for flexible-array members in unions.

Link: https://github.com/KSPP/linux/issues/193
Link: https://github.com/KSPP/linux/issues/213
Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/md/bcache/bcache_ondisk.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/md/bcache/bcache_ondisk.h b/drivers/md/bcache/bcache_ondisk.h
index 97413586195b..d086a0ce4bc2 100644
--- a/drivers/md/bcache/bcache_ondisk.h
+++ b/drivers/md/bcache/bcache_ondisk.h
@@ -359,8 +359,8 @@ struct jset {
 	__u64			prio_bucket[MAX_CACHES_PER_SET];
 
 	union {
-		struct bkey	start[0];
-		__u64		d[0];
+		DECLARE_FLEX_ARRAY(struct bkey, start);
+		DECLARE_FLEX_ARRAY(__u64, d);
 	};
 };
 
@@ -424,8 +424,8 @@ struct bset {
 	__u32			keys;
 
 	union {
-		struct bkey	start[0];
-		__u64		d[0];
+		DECLARE_FLEX_ARRAY(struct bkey, start);
+		DECLARE_FLEX_ARRAY(__u64, d);
 	};
 };
 
-- 
2.34.1

On Mon, Sep 26, 2022 at 04:43:15PM -0500, Gustavo A. R. Silva wrote:
> Zero-length arrays are deprecated and we are moving towards adopting
> C99 flexible-array members, instead. So, replace zero-length arrays
> declarations in anonymous union with the new DECLARE_FLEX_ARRAY()
> helper macro.
> 
> This helper allows for flexible-array members in unions.
> 
> Link: https://github.com/KSPP/linux/issues/193
> Link: https://github.com/KSPP/linux/issues/213
> Link: https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook