Check coroutine upvars and resume ty in dtorck constraint #144156
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Fix for #144155.
r? @lcnr or reassign 😸
Just some thoughts --- a proper fix for this whole situation would be to consider
TypingModein theneeds_dropcall, and just callingcoroutine_ty.needs_drop()in the dtorck constraint check. During MIR building, we should probably use a typing mode that stalls the local coroutines and considers them to be unconditionally drop, or perhaps just stall all coroutines in analysis mode. Then in borrowck mode, we can re-checkneeds_dropbut descend into witness types properly. #144158 implements this experimentally.This is a pretty involved fix, and conflicts with some in-flight changes (#144157) that I have around removing coroutine witnesses altogether. I'm happy to add a FIXME to rework this whole approach, but I don't want to block this quick fix since it's obviously more correct than the status-quo.