>From 19f55c05ea592b1339ee0d503c86be349447553f Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Wed, 25 Mar 2020 13:52:51 +0800 Subject: [PATCH 1/2] mdraid1x_linux: Fix gcc10 error -Werror=array-bounds We bumped into the build error while testing gcc-10 pre-release. ../../grub-core/disk/mdraid1x_linux.c: In function 'grub_mdraid_detect': ../../grub-core/disk/mdraid1x_linux.c:181:15: error: array subscript is outside array bounds of 'grub_uint16_t[0]' {aka 'short unsigned int[0]'} [-Werror=array-bounds] 181 | (char *) &sb.dev_roles[grub_le_to_cpu32 (sb.dev_number)] | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ../../grub-core/disk/mdraid1x_linux.c:98:17: note: while referencing 'dev_roles' 98 | grub_uint16_t dev_roles[0]; /* Role in array, or 0xffff for a spare, or 0xfffe for faulty. */ | ^~~~~~~~~ ../../grub-core/disk/mdraid1x_linux.c:127:33: note: defined here 'sb' 127 | struct grub_raid_super_1x sb; | ^~ cc1: all warnings being treated as errors Apparently gcc issues the warning when trying to access sb.dev_roles array's member, since it is a zero length array as the last element of struct grub_raid_super_1x that is allocated sparsely without extra chunks for the trailing bits, so the warning looks legitimate in this regard. As the whole thing here is doing offset computation, it is undue to use syntax that would imply array member access then take address from it later. Instead we could accomplish the same thing through basic array pointer arithmetic to pacify the warning. Signed-off-by: Michael Chang --- grub-core/disk/mdraid1x_linux.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/grub-core/disk/mdraid1x_linux.c b/grub-core/disk/mdraid1x_linux.c index 7cc80d3df..c980feba4 100644 --- a/grub-core/disk/mdraid1x_linux.c +++ b/grub-core/disk/mdraid1x_linux.c @@ -178,7 +178,7 @@ grub_mdraid_detect (grub_disk_t disk, return NULL; if (grub_disk_read (disk, sector, - (char *) &sb.dev_roles[grub_le_to_cpu32 (sb.dev_number)] + (char *) (sb.dev_roles + grub_le_to_cpu32 (sb.dev_number)) - (char *) &sb, sizeof (role), &role)) return NULL; -- 2.16.4