New subject: [Bug 37117] PVS-Studio Error: Shifting a negative number

16 Aug 2014


      https://bugs.winehq.org/show_bug.cgi?id=37117
Bug ID: 37117
           Summary: PVS-Studio Error: Shifting a negative number
           Product: Wine
           Version: 1.7.22
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: wine-bugs@winehq.org
          Reporter: lukebenes@hotmail.com
PVS-Studio Error: V610 Undefined behavior. Check the shift operator '<<. The
left operand '(LONGLONG) - 1' is negative. propvar.c 127
...
if (*res >= ((LONGLONG)1 << (dest_bits-1)) ||
  *res < ((LONGLONG)-1 << (dest_bits-1)))
  return HRESULT_FROM_WIN32(ERROR_ARITHMETIC_OVERFLOW);
...
The LONGLONG type is declared as 'typedef signed __int64 LONGLONG;', i.e. it is
a signed type. According to the new standard, shifting negative numbers leads
to undefined or unspecified behavior. To find out why such code still may work
and how to fix it best, see the article Wade not in unknown waters - part
three.
details on the V610 error here: http://www.viva64.com/en/d/0225/
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[Bug 37117] New: PVS-Studio Error: Shifting a negative number