[Bug c/66415] New: ice in location_column_from_byte_offset

["dcb314 at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66415

            Bug ID: 66415
           Summary: ice in location_column_from_byte_offset
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Created attachment 35695
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35695&action=edit
C source code

gcc trunk dated 20150603 does this with the attached code

ctfCompress.c: In function âctfCompress2â:
ctfCompress.c:271:4: internal compiler error: Segmentation fault
0xbcea5f crash_signal
        ../../src/trunk/gcc/toplev.c:380
0x58af2b location_column_from_byte_offset
        ../../src/trunk/gcc/c-family/c-format.c:89
0x58af2b location_from_offset
        ../../src/trunk/gcc/c-family/c-format.c:148
0x58b126 format_type_warning
        ../../src/trunk/gcc/c-family/c-format.c:2683
0x58bb8c check_format_types
        ../../src/trunk/gcc/c-family/c-format.c:2627

c-format.c:89 is

  if (*c != '"')

so maybe a reasonable bodge is to ensure c != NULL before use.