Try this C code:
SEXP set_intseq_data(SEXP x)
{
if (MAYBE_SHARED(x))
error("Oops, not supposed to do this!");
void* ptr = DATAPTR(x);
((int*)ptr)[3] = 1234;
return R_NilValue;
}
Lots of things will break if you modify objects that have been marked
as immutable (and hen
Experimenting with altrep objects and v3 serialization, I discovered a
possible bug. Calling DATAPTR on a compact_intseq object returns a
pointer to the expanded integer sequence in memory. If you modify
this data, the object values appear to be changed. However, if the
compact_intseq object is
