grub/head build with pre-release GCC10 ; fail @ "grub-core/disk/mdraid1x_linux.c:181:15: error: ..."

[PGNet Dev]

 building curren head,

        git clone https://git.savannah.gnu.org/git/grub.git
        cd grub
        git describe
                grub-2.04-71-g552c9fd08

with soon(ish)-to-be-release GCC10

        gcc --version
                gcc (SUSE Linux) 10.0.1 20200320 (experimental) [revision 
7d4549b2cd209eb621453ce13be7ffd84ffa720a]

config's OK

        unset CC CPP
        ./bootstrap
        ./autogen.sh
        ./configure

build fails,

make V=1
        ...
        gcc -DHAVE_CONFIG_H -I.  -Wall -W -DGRUB_UTIL=1 -D_FILE_OFFSET_BITS=64 
-I./include -DGRUB_FILE=\"grub-core/disk/mdraid1x_linux.c\" -I. -I. -I. -I. 
-I./include -I./include -I./grub-core/lib/libgcrypt-grub/src/  
-I./grub-core/lib/minilzo -I./grub-core/lib/xzembed -I./grub-core/lib/zstd 
-DMINILZO_HAVE_CONFIG_H -O3 -Wall -fstack-protector-strong -funwind-tables 
-fasynchronous-unwind-tables -fmessage-length=0 -grecord-gcc-switches 
-march=native -mtune=native -D_FORTIFY_SOURCE=2 -D_FILE_OFFSET_BITS=64 -Wall -W 
-Wshadow -Wpointer-arith -Wundef -Wchar-subscripts -Wcomment 
-Wdeprecated-declarations -Wdisabled-optimization -Wdiv-by-zero -Wfloat-equal 
-Wformat-extra-args -Wformat-security -Wformat-y2k -Wimplicit 
-Wimplicit-function-declaration -Wimplicit-int -Wmain -Wmissing-braces 
-Wmissing-format-attribute -Wmultichar -Wparentheses -Wreturn-type 
-Wsequence-point -Wshadow -Wsign-compare -Wswitch -Wtrigraphs -Wunknown-pragmas 
-Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value  
-Wunused-variable -Wwrite-strings -Wnested-externs -Wstrict-prototypes 
-Wcast-align  -Wextra -Wattributes -Wendif-labels -Winit-self 
-Wint-to-pointer-cast -Winvalid-pch -Wmissing-field-initializers -Wnonnull 
-Woverflow -Wvla -Wpointer-to-int-cast -Wstrict-aliasing -Wvariadic-macros 
-Wvolatile-register-var -Wpointer-sign -Wmissing-include-dirs 
-Wmissing-prototypes -Wmissing-declarations -Wformat=2 -Werror  -fno-builtin 
-Wno-undef -O3 -Wall -fstack-protector-strong -funwind-tables 
-fasynchronous-unwind-tables -fmessage-length=0 -grecord-gcc-switches 
-march=native -mtune=native -MT grub-core/disk/libgrubmods_a-mdraid1x_linux.o 
-MD -MP -MF grub-core/disk/.deps-util/libgrubmods_a-mdraid1x_linux.Tpo -c -o 
grub-core/disk/libgrubmods_a-mdraid1x_linux.o `test -f 
'grub-core/disk/mdraid1x_linux.c' || echo './'`grub-core/disk/mdraid1x_linux.c
        grub-core/disk/mdraid1x_linux.c: In function ‘grub_mdraid_detect’:
        grub-core/disk/mdraid1x_linux.c:181:15: error: array subscript 
<unknown> 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
        make[2]: *** [Makefile:7059: 
grub-core/disk/libgrubmods_a-mdraid1x_linux.o] Error 1
        make[2]: Leaving directory '/usr/local/src/grub'
        make[1]: *** [Makefile:11920: all-recursive] Error 1
        make[1]: Leaving directory '/usr/local/src/grub'
        make: *** [Makefile:3772: all] Error 2


known/expected issue? bug-worthy?  or still too early for GCC10 issues?