Decay integer-only (Optional)SymIntArrayRef to IntList in IValue (#86094)
We have logic that says if you ask for a SymIntList from an IValue, but the IValue is actually an IntList, we will still give it to you in that case (check ivalue_to_arg in aten/src/ATen/core/boxing/impl/make_boxed_from_unboxed_functor.h). However, we also need the *inverse* version of this logic, which says that if you construct an IValue from a SymIntArrayRef, and it is actually integer only, we need to store it as an IntList, so that toIntList on the IValue will work.
The way this works is a bit twisty, but our basic strategy is to disable construction of IValue from list container types that contain SymInt directly, and then directly implement variants of these constructors by hand, which iterate over the elements of the list and test if there are any SymInts or not to decide what type to construct the underlying List. These variants have to be templated, otherwise we will run afoul ambiguous overloads. I only did the overloads that actually occurred in practice; you may need to add more if you SymIntify more stuff.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86094
Approved by: https://github.com/anjali411, https://github.com/albanD
