Fix: Box(T).box allocates when T < Pointer #15562
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While discussing to use
Box(T)in #15395 I noticed thatBox(Pointer).box(ptr)allocates into the GC heap to store the pointer address into.That felt like an overlook since we don't need to allocate to box a Reference or Nil, so it should be fine to box a raw pointer without allocating an intermediary pointer. Am I missing something?
I only allowed
T < Pointerin addition to the Reference and nilable Reference cases. I'm not sure a Pointer appearing in an union along Nil or Reference would behave correctly —is it passing the{type, value}union by value?