Define a third kind of COW state; STATIC

Previously, when IsCOW flag was set there were two cases:
  SvLEN()==0:
      PV is really a shared HEK

  SvLEN()!=0:
      PV is a COW structure with 1..256 refcount stored in its extra final byte

This change adds a third state:

  SvLEN()==0 && SvFLAGS() & SVppv_STATIC:
      PV is a shared static const pointer and must not be modified

sv_setsv_flags() and sv_setsv_cow() will preserve this state

sv_uncow() will copy it out to a regular string buffer

sv_dup() will preserve the static pointer into cloned threads

0 files changed, 0 insertions, 0 deletions