BTreeMap: define forget_type only when relevant Similar to `forget_node_type` for handles. No effect on generated code, apart maybe from the superfluous calls that might not have been optimized away. r? @Mark-Simulacrum
BTreeMap: define forget_type only when relevant Similar to `forget_node_type` for handles. No effect on generated code, apart maybe from the superfluous calls that might not have been optimized away. r? @Mark-Simulacrum