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Forward pointer-union wraps of call arguments to the callee's parameter proof - #2048
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…er proof A call argument that wraps a binding into a nullable-pointer union passes the binding's pointer itself. The call-lifetimes analysis now treats it like the bare binding, so a record or instance passed to a `T | undefined` parameter that is only projected keeps its frame storage and result slot.
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… narrowed payload A union parameter's proof covered the union, not its payload: narrowing it and storing, returning or pushing the result, a narrowed nullish read, and a store into a nullable-pointer field all counted as projections. That holds for a boxed union, whose payload is a separate object. A record passed through a nullable-pointer union is that payload, so forwarding it to such a callee let a record in its caller's frame escape the frame. A pointer-wrapped argument now needs a second fact from the callee's union parameter: its payload stays in place too. The payload is in place when it is only tested, narrowed for a field read (directly or through the checked narrowing a field read of a `T | undefined` parameter compiles to), or passed on to a parameter that is proved in turn. The facts that other arguments use are unchanged. Corpus 7663 has callees that push (directly and through a non-null assertion), default, store in a global record field or a class field, or pass on the narrowed record, and one that only reads it.
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T | undefined,T | null) passes its pointer unchanged, so the call-lifetimes analysis now forwards it to the callee's parameter proof like the bare binding; callees that only read the argument let it keep its frame storage and result slot.