Examples of errors detected by the V784 diagnostic

V784. The size of the bit mask is less than the size of the first operand. This will cause the loss of the higher bits.

Perl 5

V784 The size of the bit mask is less than the size of the first operand. This will cause the loss of higher bits. inffast.c 296


void ZLIB_INTERNAL inflate_fast(z_streamp strm, unsigned start)
{
  ....
  unsigned long hold;         /* local strm->hold */
  unsigned bits;              /* local strm->bits */
  ....
  hold &= (1U << bits) - 1;
  ....
}

Clang

V784 The size of the bit mask is less than the size of the first operand. This will cause the loss of higher bits. RuntimeDyld.cpp 815


unsigned getStubAlignment() override {
  if (Arch == Triple::systemz)
    return 8;
  else
    return 1;
}

Expected<unsigned>
RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
                             const SectionRef &Section,
                             bool IsCode) {
  ....
  uint64_t DataSize = Section.getSize();
  ....
  if (StubBufSize > 0)
    DataSize &= ~(getStubAlignment() - 1);
  ....
}