While trying to update s390-tools to conform to the usrmerge change, the build
fails with the following error:
gcc -I ../../include -D_GNU_SOURCE -fno-pie -Os -g -I../..//zipl/boot
-I../..//zipl/include -I../..//include -DENABLE_SCLP_ASCII=1
-DS390_TOOLS_RELEASE=2.19.0-324.1 -fno-builtin -ffreestanding
-fno-asynchronous-unwind-tables -fno-delete-null-pointer-checks
-fno-stack-protector -fexec-charset=IBM1047 -m64 -mpacked-stack
-mstack-size=4096 -mstack-guard=128 -msoft-float -Wall -Wformat-security
-Wextra -Werror -c stage3a.c -o stage3a.o
 In file included from stage3a.c:14:
 In function '__test_facility',
     inlined from 'test_facility' at ../../include/boot/s390.h:428:9,
     inlined from 'start' at stage3a.c:42:7:
 ../../include/boot/s390.h:418:17: error: array subscript 0 is outside array
bounds of 'void[0]' [-Werror=array-bounds]
   418 |         return (*ptr & (0x80 >> (nr & 7))) != 0;
       |                 ^~~~
 cc1: all warnings being treated as errors
 make[2]: *** [../../common.mak:268: stage3a.o] Error 1
 make[2]: Leaving directory
'/home/abuild/rpmbuild/BUILD/s390-tools-2.19.0/genprotimg/boot'
 make[1]: *** [Makefile:22: all-recursive] Error 1
 make: *** [Makefile:51: genprotimg] Error 2

The failure can be seen in both
https://build.opensuse.org/package/show/home:markkp:branches:Base:System/s390-tools
and https://build.opensuse.org/package/show/Base:System/s390-tools

The last successful build was on May 11, 2022. From what I can tell, that build
was performed with gcc11, so it appears that gcc12 is detecting something that
previous versions did not.