#rust-lang

ubsan_: there is a potential really jank trick of a dst return poping base ptr, return ptr, etc and then doing an alloca

which then is associated with the callee's now-larger stack fram

alloca here takes the same roll as malloc

for box (t: SomeDst)

or box mk_dst()

more realistically

except that has no get-rid-of-stackframe requirement

(alternatively return pointer / base pointer / something else stays in place and we "leak stack"

....these things probably require LLVM work but thought I'd throw out