feat(ts): drop a whole B-tree node by node as std's drop_tree does

quest/m3/README.md

@@ -26,4 +26,3 @@ generic std gap is planned here even when moq never calls it.
 - [rust2-ts with no ts.toml](/quest/m3/ts-configless.md) - a crate's whole `pub` API translates with no config and no bound items
 - [Buf on a deque of bytes](/quest/m3/ts-vecdeque-buf.md) - `bytes`' `Buf` for a deque of bytes translates
 - [std's panic messages hold std's capacity](/quest/m3/ts-panic-payload-capacity.md) - a hook reads native's `String` capacity from std's own formatted panics
-- [A B-tree drops as std's does](/quest/m3/ts-btree-drop-order.md) - keys and values drop node by node, in std's order

ts/README.md

@@ -1025,10 +1025,11 @@ they need.
   where JS fails to allocate a byte `Vec`'s or `VecDeque`'s `Uint8Array` (decided with the
   maintainer on 2026-11-03). A `LinkedList` is nodes linked both ways, as std's are,
   so `append` is O(1) and `split_off` walks from the nearer end; each node is the place
-  `iter_mut` and `front_mut` lend of an item JS copies. Dropping a whole map or set drops its entries in the
-  runtime's order, keys' for a B-tree, not std's node by node: std leaves that order
-  undocumented ([#272](https://github.com/moq-dev/rust2/pull/272)). Maintainer's decision
-  on 2026-10-30; a map's `IntoIter` still drops in std's order.
+  `iter_mut` and `front_mut` lend of an item JS copies. Dropping a whole hash map or set drops its entries in the
+  runtime's order, not hashbrown's: std leaves that order undocumented
+  ([#272](https://github.com/moq-dev/rust2/pull/272)). Maintainer's decision on 2026-10-30.
+  A whole B-tree drops as std's `drop_tree` does, node by node in postorder, and its
+  `IntoIter` in key order, as std's does.
 - A slice's `sort` and `sort_unstable` are std's driftsort and ipnsort, ported to the
   runtime with the choices std makes by the element's size on wasm32 and whether it is
   `Freeze` and `Copy`, so each calls the comparator in std's order and leaves equal

ts/fixtures/lang/collections/expected/collections.Tagged.ts

@@ -0,0 +1,37 @@
+// Generated by rust2-ts. Do not edit.
+
+import * as rs from "./rs.ts";
+
+/**
+ * A B-tree value, or a set's key, that logs its tag as it drops, ordered by it. A clone's
+ * tag is 1000 past the original's.
+ */
+export class Tagged {
+	_0: rs.u16;
+	_1: rs.RefCell<rs.Vec<rs.u16>>;
+
+	constructor(_0: rs.u16, _1: rs.RefCell<rs.Vec<rs.u16>>) {
+		this._0 = _0;
+		this._1 = _1;
+	}
+
+	[Symbol.dispose](): void {
+		drop$ops_Drop(this);
+	}
+}
+
+export function drop$ops_Drop(self: Tagged): void {
+	const _5: rs.RefCell<rs.Vec<rs.u16>> = rs.refCellBorrowMut(self._1);
+	_5.value.items.push(self._0);
+	rs.refMutRelease(_5);
+}
+
+export function clone$Clone(self: Tagged): Tagged {
+	return new Tagged(rs.u16Add(self._0, 1000), self._1);
+}
+
+export function cmp$cmp_Ord(self: Tagged, other: Tagged): rs.Ordering {
+	return rs.cmp(self._0, other._0);
+}
+
+//# sourceMappingURL=collections.Tagged.ts.map

ts/fixtures/lang/collections/expected/collections.ts

@@ -1,7 +1,7 @@
 // Generated by rust2-ts. Do not edit.
 
 import * as rs from "./rs.ts";
-import { copy$Option_collections_Tally, copy$array_collections_Quirky, copy$array_tuple2_u8_u16, copy$array_tuple2_u8_u8, copy$array_u8, copy$collections_Bumped, copy$collections_Quirky, copy$collections_Tally, copy$collections_Wrap_u8, copy$tuple2_u8_collections_Tally, copy$tuple2_u8_u16, copy$tuple2_u8_u8, drop$Option_tuple2_collections_Logged_collections_Logged, drop$ops_Range_collections_Logged, drop$tuple2_collections_Logged_collections_Logged, drop$tuple2_ops_Bound_collections_Logged_ops_Bound_collections_Logged, drop$tuple2_sync_Arc_collections_Picky_u8 } from "./lib.ts";
+import { copy$Option_collections_Tally, copy$array_collections_Quirky, copy$array_tuple2_u8_u16, copy$array_tuple2_u8_u8, copy$array_u8, copy$collections_Bumped, copy$collections_Quirky, copy$collections_Tally, copy$collections_Wrap_u8, copy$tuple2_u8_collections_Tally, copy$tuple2_u8_u16, copy$tuple2_u8_u8, drop$Option_tuple2_collections_Logged_collections_Logged, drop$Option_tuple2_u16_collections_Tagged, drop$collections_BTreeMap_u16_collections_Tagged, drop$ops_Range_collections_Logged, drop$tuple2_collections_Logged_collections_Logged, drop$tuple2_ops_Bound_collections_Logged_ops_Bound_collections_Logged, drop$tuple2_sync_Arc_collections_Picky_u8 } from "./lib.ts";
 import type * as Boxed from "./collections.Boxed.ts";
 import * as Bumped from "./collections.Bumped.ts";
 import * as ByRef from "./collections.ByRef.ts";
@@ -23,6 +23,7 @@ import * as Probe from "./collections.Probe.ts";
 import * as Quirky from "./collections.Quirky.ts";
 import * as Rank from "./collections.Rank.ts";
 import * as Right from "./collections.Right.ts";
+import * as Tagged from "./collections.Tagged.ts";
 import * as Tally from "./collections.Tally.ts";
 import * as Window from "./collections.Window.ts";
 import * as Wrap from "./collections.Wrap.ts";
@@ -5926,36 +5927,34 @@ export function btreeExtracts(kind: rs.u8, data: rs.ByteSlice, out: rs.ByteVec):
 		rs.byteVecPush(out, _302 === undefined ? 1 : 0);
 		drop$Option_tuple2_collections_Logged_collections_Logged(_302);
 		rs.drop(it4);
-		rs.iterForEach(rs.btreeIter(map2, rs.drop, rs.drop), (a0: [Logged.Logged, Logged.Logged]): undefined => {
-			drop$tuple2_collections_Logged_collections_Logged(a0);
-		}, true);
+		rs.btreeDrop(map2, rs.drop, rs.drop);
 		const bytes: rs.BTreeMap<rs.u16, rs.u8> = rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, rs.u8>;
 		const window: (a0: rs.u16, a1: rs.u16) => Window.Window = (lo2: rs.u16, hi2: rs.u16): Window.Window => {
 			return { lo: lo2, hi: hi2, log };
 		};
-		const _315: Window.Window = window(0, 9);
-		rs.iterForEach(rs.btreeExtractIfMut(bytes, rs.boundsOf(_315, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), (_26: rs.u16, _310: rs.Place<rs.u8>): boolean => {
+		const _314: Window.Window = window(0, 9);
+		rs.iterForEach(rs.btreeExtractIfMut(bytes, rs.boundsOf(_314, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), (_26: rs.u16, _310: rs.Place<rs.u8>): boolean => {
 			return true;
-		}), (_a02: [rs.u16, rs.u8]): undefined => {
+		}), (_a0: [rs.u16, rs.u8]): undefined => {
 			undefined;
 		});
 		rs.btreeInsert(bytes, 1, 1);
 		rs.btreeRemove(bytes, 1);
-		const _326: Window.Window = window(0, 9);
-		rs.iterForEach(rs.btreeExtractIfMut(bytes, rs.boundsOf(_326, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), (_27: rs.u16, _311: rs.Place<rs.u8>): boolean => {
+		const _325: Window.Window = window(0, 9);
+		rs.iterForEach(rs.btreeExtractIfMut(bytes, rs.boundsOf(_325, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), (_27: rs.u16, _311: rs.Place<rs.u8>): boolean => {
 			return true;
-		}), (_a03: [rs.u16, rs.u8]): undefined => {
+		}), (_a02: [rs.u16, rs.u8]): undefined => {
 			undefined;
 		});
-		const _331: rs.Iter<[rs.u16, rs.u8]> = rs.iterMap(new rs.Range(0, n), (k3: rs.u16): [rs.u16, rs.u8] => {
+		const _330: rs.Iter<[rs.u16, rs.u8]> = rs.iterMap(new rs.Range(0, n), (k3: rs.u16): [rs.u16, rs.u8] => {
 			return [k3, k3 & 0xff] as [rs.u16, rs.u8];
 		});
-		rs.btreeExtend(bytes, _331);
-		const _336: Window.Window = window(rs.u16Div(lo, 2), rs.u16Div(hi, 2));
-		const _343: (a0: rs.u16, a1: rs.Place<rs.u8>) => boolean = (k4: rs.u16, _314: rs.Place<rs.u8>): boolean => {
+		rs.btreeExtend(bytes, _330);
+		const _335: Window.Window = window(rs.u16Div(lo, 2), rs.u16Div(hi, 2));
+		const _342: (a0: rs.u16, a1: rs.Place<rs.u8>) => boolean = (k4: rs.u16, _315: rs.Place<rs.u8>): boolean => {
 			return rs.u16Rem(k4, every) === 0;
 		};
-		rs.iterExtendBytes(out, rs.iterMap(rs.iterSlice(rs.iterToVec(rs.btreeExtractIfMut(bytes, rs.boundsOf(_336, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), _343), "next", 4).items), (_210: [rs.u16, rs.u8]): rs.u8 => {
+		rs.iterExtendBytes(out, rs.iterMap(rs.iterSlice(rs.iterToVec(rs.btreeExtractIfMut(bytes, rs.boundsOf(_335, Window.startBound$ops_RangeBounds_u16, Window.endBound$ops_RangeBounds_u16), _342), "next", 4).items), (_210: [rs.u16, rs.u8]): rs.u8 => {
 			return _210[1];
 		}), undefined, true);
 		rs.iterExtendBytes(out, rs.iterFlatMap(rs.iterSlice(rs.refCellReplace(log, new rs.Vec()).items), (e: rs.u16): Uint8Array => {
@@ -6451,4 +6450,182 @@ export function btreeBorrows(kind: rs.u8, data: rs.ByteSlice, out: rs.ByteVec):
 	put(out, part25);
 }
 
+/**
+ * Whole B-trees whose entries log as they drop, which std drops node by node, each node's
+ * entries in order after its children's: maps built by random, ascending, and descending
+ * inserts and by `collect`, emptied in part by removals that merge nodes, cleared, assigned
+ * over, retained, split, cloned, and nested, sets, and `IntoIter`, which drops what it still
+ * holds in key order. The first byte sets how many entries, up to 297 so trees reach height
+ * 2, and the rest seed the keys. Each drop is logged, with a mark between the steps.
+ */
+export function btreeDrops(kind: rs.u8, data: rs.ByteSlice, out: rs.ByteVec): void {
+	let _201!: rs.u16;
+	const log: rs.RefCell<rs.Vec<rs.u16>> = new rs.RefCell(new rs.Vec());
+	const tag: (a0: rs.u16) => Tagged.Tagged = (k4: rs.u16): Tagged.Tagged => {
+		return new Tagged.Tagged(k4, log);
+	};
+	const mark: (a0: rs.u16) => undefined = (m: rs.u16): undefined => {
+		const _55: rs.RefCell<rs.Vec<rs.u16>> = rs.refCellBorrowMut(log);
+		_55.value.items.push(61440 | m);
+		rs.refMutRelease(_55);
+	};
+	const n: rs.u16 = rs.u16Div(rs.u16Mul(option_unwrapOr$1fr498u(rs.byteSliceFirst(data), 0) as rs.u16, 7), 6);
+	let state: rs.u32 = (rs.iterFold(rs.iterSlice(rs.byteSliceView(data)), 2654435769, (s: rs.u32, _32: rs.u8): rs.u32 => {
+		return (rs.intRotateLeft(s, 5, 32, false) ^ _32 as rs.u32) >>> 0;
+	}) | 1) >>> 0;
+	const key: () => rs.u16 = (): rs.u16 => {
+		state = (state ^ ((state << 13) >>> 0)) >>> 0;
+		state = (state ^ (state >>> 17)) >>> 0;
+		state = (state ^ ((state << 5) >>> 0)) >>> 0;
+		return rs.u32Rem(state, 400) & 0xffff;
+	};
+	const random: (a0: rs.u16) => rs.BTreeMap<rs.u16, Tagged.Tagged> = (count: rs.u16): rs.BTreeMap<rs.u16, Tagged.Tagged> => {
+		const map8: rs.BTreeMap<rs.u16, Tagged.Tagged> = rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>;
+		let iterStart9: rs.u16 = 0;
+		const iterEnd9: rs.u16 = count;
+		while (true) {
+			if (!(iterStart9++ < iterEnd9)) {
+				return map8;
+			}
+			const k5: rs.u16 = key();
+			const _133: Tagged.Tagged = tag(k5);
+			rs.drop(rs.btreeInsert(map8, k5, _133));
+		}
+	};
+	const _26: rs.u8 = rs.u8Rem(kind, 10);
+	if (_26 === 0) {
+		const map: rs.BTreeMap<rs.u16, Tagged.Tagged> = random(n);
+		mark(0);
+		rs.btreeDrop(map, undefined, rs.drop);
+	} else if (_26 === 1) {
+		rs.btreeDrop(rs.iterFold(new rs.Range(0, n), rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>, (map9: rs.BTreeMap<rs.u16, Tagged.Tagged>, k8: rs.u16): rs.BTreeMap<rs.u16, Tagged.Tagged> => {
+			const _65: Tagged.Tagged = tag(k8);
+			rs.drop(rs.btreeInsert(map9, k8, _65));
+			return map9;
+		}), undefined, rs.drop);
+		mark(0);
+		rs.btreeDrop(rs.iterFold(rs.iterRev(new rs.Range(0, n)), rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>, (map10: rs.BTreeMap<rs.u16, Tagged.Tagged>, k9: rs.u16): rs.BTreeMap<rs.u16, Tagged.Tagged> => {
+			const _66: Tagged.Tagged = tag(k9);
+			rs.drop(rs.btreeInsert(map10, k9, _66));
+			return map10;
+		}), undefined, rs.drop);
+	} else if (_26 === 2) {
+		const _57: rs.Iter<[rs.u16, Tagged.Tagged]> = rs.iterMap(rs.vecIntoIter(rs.iterToVec(rs.iterMap(new rs.Range(0, n), (_22: rs.u16): rs.u16 => {
+			return key();
+		}), undefined, 2, true)), (k7: rs.u16): [rs.u16, Tagged.Tagged] => {
+			return [k7, tag(k7)] as [rs.u16, Tagged.Tagged];
+		});
+		const map2: rs.BTreeMap<rs.u16, Tagged.Tagged> = rs.btreeCollect(rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>, rs.iterToVec(_57, undefined, 12, true).items, 12, true, undefined, undefined, rs.drop);
+		mark(0);
+		rs.btreeDrop(map2, undefined, rs.drop);
+	} else if (_26 === 3) {
+		const map3: rs.BTreeMap<rs.u16, Tagged.Tagged> = random(n);
+		let iterStart: rs.u16 = 0;
+		const iterEnd: rs.u16 = n;
+		while (iterStart++ < iterEnd) {
+			const k: rs.u16 = key();
+			if (rs.u16Rem(k, 3) !== 0) {
+				rs.drop(rs.btreeRemove(map3, k));
+			}
+		}
+		const _85: rs.u16 = rs.u16Div(n, 8);
+		let iterStart2: rs.u16 = 0;
+		const iterEnd2: rs.u16 = _85;
+		while (iterStart2++ < iterEnd2) {
+			drop$Option_tuple2_u16_collections_Tagged(rs.btreePop(map3));
+			drop$Option_tuple2_u16_collections_Tagged(rs.btreePop(map3, true));
+		}
+		mark(0);
+		rs.btreeDrop(map3, undefined, rs.drop);
+	} else if (_26 === 4) {
+		const set: rs.BTreeSet<Tagged.Tagged> = rs.btreeNew(Tagged.cmp$cmp_Ord) as rs.BTreeSet<Tagged.Tagged>;
+		let iterStart3: rs.u16 = 0;
+		const iterEnd3: rs.u16 = n;
+		while (iterStart3++ < iterEnd3) {
+			const part2 = key();
+			const _111: Tagged.Tagged = tag(part2);
+			rs.btreeAdd(set, _111, rs.drop);
+		}
+		const _118: rs.u16 = rs.u16Div(n, 2);
+		let iterStart4: rs.u16 = 0;
+		const iterEnd4: rs.u16 = _118;
+		while (iterStart4++ < iterEnd4) {
+			const part3 = key();
+			const _127: Tagged.Tagged = tag(part3);
+			rs.btreeDelete(set, _127, rs.drop);
+			_127[Symbol.dispose]();
+		}
+		mark(0);
+		rs.btreeDrop(set, rs.drop);
+	} else if (_26 === 5) {
+		const map4: rs.BTreeMap<rs.u16, rs.BTreeMap<rs.u16, Tagged.Tagged>> = rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, rs.BTreeMap<rs.u16, Tagged.Tagged>>;
+		let iterStart5: rs.u16 = 0;
+		const iterEnd5: rs.u16 = n;
+		while (iterStart5++ < iterEnd5) {
+			const _146: [rs.u16, rs.u16] = [rs.u16Rem(key(), 24), key()];
+			const k2: rs.u16 = _146[0];
+			const j: rs.u16 = _146[1];
+			rs.drop(rs.btreeInsert(rs.entryOrInsertWith(rs.entry(map4, k2), (): rs.BTreeMap<rs.u16, Tagged.Tagged> => {
+				return rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>;
+			}), j, tag(j)));
+		}
+		mark(0);
+		rs.btreeDrop(map4, undefined, drop$collections_BTreeMap_u16_collections_Tagged);
+	} else if (_26 === 6) {
+		const iter6: rs.Iter<[rs.u16, Tagged.Tagged]> = rs.btreeIter(random(n), undefined, rs.drop);
+		let iterStart6: rs.usize = 0;
+		const iterEnd6: rs.usize = data.length;
+		while (iterStart6++ < iterEnd6) {
+			drop$Option_tuple2_u16_collections_Tagged(rs.iterToOption(iter6.next()));
+			drop$Option_tuple2_u16_collections_Tagged(rs.iterToOption(iter6.nextBack()));
+		}
+		mark(0);
+		rs.drop(iter6);
+	} else if (_26 === 7) {
+		let map5: rs.BTreeMap<rs.u16, Tagged.Tagged> = random(n);
+		mark(0);
+		rs.btreeClear(map5, undefined, rs.drop);
+		mark(1);
+		let iterStart7: rs.u16 = 0;
+		const iterEnd7: rs.u16 = n;
+		while ((_201 = iterStart7++) < iterEnd7) {
+			const k3: rs.u16 = _201;
+			rs.drop(rs.btreeInsert(map5, k3, tag(k3)));
+		}
+		const _210: rs.BTreeMap<rs.u16, Tagged.Tagged> = rs.btreeNew(rs.cmp) as rs.BTreeMap<rs.u16, Tagged.Tagged>;
+		rs.btreeDrop(map5, undefined, rs.drop);
+		map5 = _210;
+		const part = rs.btreeLen(map5) & 0xffff;
+		mark(part);
+		rs.btreeDrop(map5, undefined, rs.drop);
+	} else if (_26 === 8) {
+		const map6: rs.BTreeMap<rs.u16, Tagged.Tagged> = random(n);
+		rs.btreeRetain(map6, (k6: rs.u16, _35: Tagged.Tagged): boolean => {
+			return rs.u16Rem(k6, 5) !== 0;
+		}, undefined, rs.drop);
+		mark(0);
+		const high: rs.BTreeMap<rs.u16, Tagged.Tagged> = rs.btreeSplitOff(map6, 200);
+		rs.btreeDrop(map6, undefined, rs.drop);
+		mark(1);
+		rs.btreeDrop(high, undefined, rs.drop);
+	} else {
+		const map7: rs.BTreeMap<rs.u16, Tagged.Tagged> = random(n);
+		const _239: rs.u16 = rs.u16Div(n, 2);
+		let iterStart8: rs.u16 = 0;
+		const iterEnd8: rs.u16 = _239;
+		while (iterStart8++ < iterEnd8) {
+			const _249: rs.u16 = key();
+			rs.drop(rs.btreeRemove(map7, _249));
+		}
+		mark(0);
+		const copy: rs.BTreeMap<rs.u16, Tagged.Tagged> = rs.btreeClone(map7, undefined, Tagged.clone$Clone);
+		rs.btreeDrop(map7, undefined, rs.drop);
+		mark(1);
+		rs.btreeDrop(copy, undefined, rs.drop);
+	}
+	rs.iterExtendBytes(out, rs.iterFlatMap(rs.iterSlice(rs.refCellReplace(log, new rs.Vec()).items), (e: rs.u16): Uint8Array => {
+		return rs.u16ToBeBytes(e);
+	}, (value: Uint8Array) => rs.iterSlice(value), true, 2), undefined, true);
+}
+
 //# sourceMappingURL=collections.ts.map