FA-90801 / Garbage collector invariants / Open access

Oop maps: primitive arrays scanned like object arrays · case 01

Integers stored in int[] arrays keep unrelated objects alive.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Every array kind takes the object-array path.

VERIFIED REPAIR

Only object arrays have reference elements.

Unsuccessful approach: Testing for non-instance kinds still routes primitive arrays to the element scan.

Case contract

Precise tracing with per-class reference maps. Objects are word lists: words 0-1 are the header; object arrays keep their length in word 2 and elements in words 3..3+len-1 (anything after is padding); primitive arrays contain no references. Instance classes list [offset, count] runs of reference words and inherit all superclass runs. A reference word of 0 is null; a nonzero reference that is not an object id is reported as [object, word]. Return the reachable ids and the bad references.

Why this case matters

Tracing must follow exactly the reference words described by type metadata, no more and no less.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(classes, objects, roots):
    def ref_slots(o):
        ob = objects[o]
        cls = classes[ob['class']]
        if cls['kind'].endswith('array'):
            return list(range(3, 3 + ob['words'][2]))
        if cls['kind'] == 'primarray':
            return []
        slots = []
        c = ob['class']
        while c is not None:
            for off, cnt in classes[c]['maps']:
                slots.extend(range(off, off + cnt))
            c = classes[c]['super']
        return slots
    seen = set()
    stack = list(roots)
    bad = []
    while stack:
        o = stack.pop()
        if o in seen:
            continue
        seen.add(o)
        words = objects[o]['words']
        for s in ref_slots(o):
            v = words[s]
            if v == 0:
                continue
            if v not in objects:
                bad.append([o, s])
                continue
            stack.append(v)
    return {'live': sorted(seen), 'bad': sorted(bad)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [105]),
   {'bad': [], 'live': [105]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})]]
for label, args, expected in cases[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
regression: trace through fields, arrays and subclasses	`{'bad': [[103, 4]], 'live': [100, 101, 102, 103, 104, 106, 107]}`	`{'bad': [], 'live': [100, 101, 102, 103, 104, 107]}`	Failed
object array elements and trailing padding	`{'bad': [[103, 4]], 'live': [102, 103, 104, 106, 107]}`	`{'bad': [], 'live': [102, 103, 104, 107]}`	Failed
primitive array contents are not references	`{'bad': [[103, 4]], 'live': [103, 106, 107]}`	`{'bad': [], 'live': [103]}`	Failed
inherited reference field of a subclass	`{'bad': [], 'live': [104, 107]}`	`{'bad': [], 'live': [104, 107]}`	Passed
integer field that equals an object id	`{'bad': [], 'live': [101, 105, 109]}`	`{'bad': [], 'live': [101, 105, 109]}`	Passed
control: base object without references	`{'bad': [], 'live': [106]}`	`{'bad': [], 'live': [106]}`	Passed

SHA-256 / cf1ced3d69092b250ebc9571d7877146818bc46ca0aef28e0aac7208d9dba35b

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(classes, objects, roots):
    def ref_slots(o):
        ob = objects[o]
        cls = classes[ob['class']]
        if cls['kind'] != 'instance':
            return list(range(3, 3 + ob['words'][2]))
        if cls['kind'] == 'primarray':
            return []
        slots = []
        c = ob['class']
        while c is not None:
            for off, cnt in classes[c]['maps']:
                slots.extend(range(off, off + cnt))
            c = classes[c]['super']
        return slots
    seen = set()
    stack = list(roots)
    bad = []
    while stack:
        o = stack.pop()
        if o in seen:
            continue
        seen.add(o)
        words = objects[o]['words']
        for s in ref_slots(o):
            v = words[s]
            if v == 0:
                continue
            if v not in objects:
                bad.append([o, s])
                continue
            stack.append(v)
    return {'live': sorted(seen), 'bad': sorted(bad)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [105]),
   {'bad': [], 'live': [105]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})]]
for label, args, expected in cases[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
regression: trace through fields, arrays and subclasses	`{'bad': [[103, 4]], 'live': [100, 101, 102, 103, 104, 106, 107]}`	`{'bad': [], 'live': [100, 101, 102, 103, 104, 107]}`	Failed
object array elements and trailing padding	`{'bad': [[103, 4]], 'live': [102, 103, 104, 106, 107]}`	`{'bad': [], 'live': [102, 103, 104, 107]}`	Failed
primitive array contents are not references	`{'bad': [[103, 4]], 'live': [103, 106, 107]}`	`{'bad': [], 'live': [103]}`	Failed
inherited reference field of a subclass	`{'bad': [], 'live': [104, 107]}`	`{'bad': [], 'live': [104, 107]}`	Passed
integer field that equals an object id	`{'bad': [], 'live': [101, 105, 109]}`	`{'bad': [], 'live': [101, 105, 109]}`	Passed
control: base object without references	`{'bad': [], 'live': [106]}`	`{'bad': [], 'live': [106]}`	Passed

SHA-256 / c9bc558dfc7779fbaab941ccdb1e2dc670cfc2cf2a960c2c12dfaeb10098323b

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(classes, objects, roots):
    def ref_slots(o):
        ob = objects[o]
        cls = classes[ob['class']]
        if cls['kind'] == 'objarray':
            return list(range(3, 3 + ob['words'][2]))
        if cls['kind'] == 'primarray':
            return []
        slots = []
        c = ob['class']
        while c is not None:
            for off, cnt in classes[c]['maps']:
                slots.extend(range(off, off + cnt))
            c = classes[c]['super']
        return slots
    seen = set()
    stack = list(roots)
    bad = []
    while stack:
        o = stack.pop()
        if o in seen:
            continue
        seen.add(o)
        words = objects[o]['words']
        for s in ref_slots(o):
            v = words[s]
            if v == 0:
                continue
            if v not in objects:
                bad.append([o, s])
                continue
            stack.append(v)
    return {'live': sorted(seen), 'bad': sorted(bad)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 6, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 7, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 8, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [105]),
   {'bad': [], 'live': [105]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 9, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [106]),
   {'bad': [], 'live': [106]})],
 [('regression: trace through fields, arrays and subclasses',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [100]),
   {'bad': [], 'live': [100, 101, 102, 103, 104, 107]}),
  ('object array elements and trailing padding',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [102]),
   {'bad': [], 'live': [102, 103, 104, 107]}),
  ('primitive array contents are not references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [103]),
   {'bad': [], 'live': [103]}),
  ('inherited reference field of a subclass',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [104]),
   {'bad': [], 'live': [104, 107]}),
  ('integer field that equals an object id',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [109, 101]),
   {'bad': [], 'live': [101, 105, 109]}),
  ('control: base object without references',
   ({'Base': {'kind': 'instance', 'maps': [[2, 1]], 'super': None},
     'Derived': {'kind': 'instance', 'maps': [[4, 2]], 'super': 'Base'},
     'Leaf': {'kind': 'instance', 'maps': [], 'super': 'Derived'},
     'Object[]': {'kind': 'objarray', 'maps': [], 'super': None},
     'int[]': {'kind': 'primarray', 'maps': [], 'super': None}},
    {100: {'class': 'Derived', 'words': [51966, 0, 101, 7, 102, 0, 999]},
     101: {'class': 'Base', 'words': [51966, 0, 0, 105]},
     102: {'class': 'Object[]', 'words': [51966, 0, 2, 103, 104, 106]},
     103: {'class': 'int[]', 'words': [51966, 0, 3, 106, 10, 107]},
     104: {'class': 'Leaf', 'words': [51966, 0, 0, 108, 0, 107, 0]},
     105: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     106: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     107: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     108: {'class': 'Base', 'words': [51966, 0, 0, 0]},
     109: {'class': 'Derived', 'words': [51966, 0, 105, 106, 0, 0, 0]}},
    [107]),
   {'bad': [], 'live': [107]})]]
for label, args, expected in cases[N - 1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
regression: trace through fields, arrays and subclasses	`{'bad': [], 'live': [100, 101, 102, 103, 104, 107]}`	`{'bad': [], 'live': [100, 101, 102, 103, 104, 107]}`	Passed
object array elements and trailing padding	`{'bad': [], 'live': [102, 103, 104, 107]}`	`{'bad': [], 'live': [102, 103, 104, 107]}`	Passed
primitive array contents are not references	`{'bad': [], 'live': [103]}`	`{'bad': [], 'live': [103]}`	Passed
inherited reference field of a subclass	`{'bad': [], 'live': [104, 107]}`	`{'bad': [], 'live': [104, 107]}`	Passed
integer field that equals an object id	`{'bad': [], 'live': [101, 105, 109]}`	`{'bad': [], 'live': [101, 105, 109]}`	Passed
control: base object without references	`{'bad': [], 'live': [106]}`	`{'bad': [], 'live': [106]}`	Passed

SHA-256 / 83b88a19f8ef29656bb5f53b04828216dd0677d2a8cfd5a82ca28f9598c83c1a

Verification & scope

A deterministic, bounded teaching model of one garbage-collector mechanism with stipulated rules; it is not a production collector and claims no conformance to any particular runtime. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:51:30.093006+00:00.

Case digest / 91a2276483caac0b303c59c446107c0e7a8a36cf9c4ba827fecb9fdcc45aefdb