[Bug libfortran/81986] New: sanitizer detects negation of large number in string.c

[zeccav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81986

            Bug ID: 81986
           Summary: sanitizer detects negation of large number in string.c
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zeccav at gmail dot com
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
             Build: trunk 251201

! from test case pr66311.f90
! must be compiled and run
! libgfortran/runtime/string.c:199:11: runtime error: negation of
0x80000000000000000000000000000000 cannot be represented in type '__int128';
cast to an unsigned type to negate this value to itself
      character(len=100) :: buffer
      write(buffer,*) -huge(0_16)-1
      end