{"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"`T`,"}]}
`T`, and all its fields are ZSTs except for exactly one field of type `T`, then
layout, size, and ABI as its single non-ZST field. If it is generic over a type
it has the same layout and ABI as `T` (even if `T` is a ZST when monomorphized).