Properly resolve source_ref when constructing shape guards (#91058)
Whenever you guard on something, you're supposed to tell GuardBuilder about it, so GuardBuilder knows that it has to actually bind it in scope when it creates the guard function. But shape env guards bypass that mechanism completely. Well, now they don't.
For the most part, this didn't matter in practice, because we usually had a `TENSOR_MATCH` guard floating around that made sure that the guard stayed live. But if we ever eliminate those guards (e.g., because we build it into the shape guard directly; something we'll probably want to do when https://github.com/pytorch/pytorch/pull/89707 goes online) then this will indeed matter.
One complication: some of the shape env guards are on globals. You have to make sure to shunt the usage to the correct guard builder in that case. Maybe it would be better if we refactored things so there is only one GuardBuilder. Not sure.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91058
Approved by: https://github.com/voznesenskym
