なるほど
// makeBase(a : Int) -> Base sil @main.makeBase (a : Swift.Int) -> main.Base : $@convention(thin) (Int) -> @owned Base { bb0(%0 : $Int): %1 = alloc_ref $Base, scope 6 // users: %6, %7 %2 = alloc_ref $Base, scope 16 // users: %8, %5, %4, %3 debug_value %2 : $Base, let, name "self", loc "<stdin>":10:15, scope 23 // id: %3 debug_value %2 : $Base, let, name "s", argno 1, loc "<stdin>":4:10, scope 29 // id: %4 debug_value %2 : $Base, let, name "s", argno 1, loc "<stdin>":4:10, scope 29 // id: %5 %6 = value_metatype $@thick Base.Type, %1 : $Base, loc "<stdin>":15:10, scope 32 // user: %7 dealloc_partial_ref %1 : $Base, %6 : $@thick Base.Type, loc "<stdin>":15:10, scope 32 // id: %7 return %2 : $Base, loc "<stdin>":20:3, scope 4 // id: %8 } // end sil function 'main.makeBase (a : Swift.Int) -> main.Base'