[Bug c/92397] New: real.c -Warray-bounds suspicious warning

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92397

            Bug ID: 92397
           Summary: real.c -Warray-bounds suspicious warning
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

I am in the middle of a ubsan bootstrap, and saw this:

./../trunk/gcc/real.c: In function ‘void real_roundeven(real_value*,
format_helper, const real_value*)’:
../../trunk/gcc/real.c:423:13: warning: array subscript 3 is above array bounds
of ‘long unsigned int [3]’ [-Warray-bounds]
  423 |   r->sig[w] &= ~(((unsigned long)1 << (n % HOST_BITS_PER_LONG)) - 1);
      |   ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../trunk/gcc/coretypes.h:449,
                 from ../../trunk/gcc/real.c:24:
../../trunk/gcc/real.h:56:17: note: while referencing ‘real_value::sig’
   56 |   unsigned long sig[SIGSZ];
      |                 ^~~