[Bug libfortran/67534] New: libgfortran.h sanitizer complains on left shift of ~0 runtime error: left shift of negative value -1

[zeccav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67534

            Bug ID: 67534
           Summary: libgfortran.h sanitizer complains on left shift of ~0
                    runtime error: left shift of negative value -1
           Product: gcc
           Version: 5.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zeccav at gmail dot com
  Target Milestone: ---

The sanitizer complains on libgfortran.h:408

((~((index_type) 0) >> GFC_DTYPE_SIZE_SHIFT) << GFC_DTYPE_SIZE_SHIFT)

issuing

runtime error: left shift of negative value -1

because 0 is int. I believe it must be 0u to avoid undefined behaviour as in


((~((index_type) 0u) >> GFC_DTYPE_SIZE_SHIFT) << GFC_DTYPE_SIZE_SHIFT)

Target: x86_64-unknown-linux-gnu