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FA-50341 / Raster clipping / Open access

Saved clip stack: save alias · case 01

Saving aliases the mutable clip so later in-place intersections corrupt the saved region.

Verified by executionVariant 1 · 11 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Saving aliases the mutable clip so later in-place intersections corrupt the saved region.

THE FAILURE

Saving aliases the mutable clip so later in-place intersections corrupt the saved region.

Unsuccessful approach: Copying the region fixes aliasing, but reconstructing the saved enable flag as true loses disabled scopes.

Case contract

Commands act on finite sample indices [0,size). Save/restore includes the clip-enable bit; region edits update stored coverage even while clipping is disabled. Restore underflow is inert. Draw emits sorted effective samples.

Why this case matters

Raster clip state can leak coverage across draws even when every individual region is valid.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(commands, size):
    full=set(range(size))
    clip=set(full)
    enabled=True
    stack=[]
    out=[]
    for cmd in commands:
        op=cmd[0]
        mask=set(cmd[1]) & full if len(cmd)>1 else set()
        if op=='save': stack.append((clip,enabled))
        elif op=='restore':
            if stack: clip,enabled=stack.pop()
        elif op=='intersect': clip &= mask
        elif op=='exclude': clip -= mask
        elif op=='union': clip |= mask
        elif op=='replace': clip=set(mask)
        elif op=='invert': clip=full-clip
        elif op=='reset': clip=set(full)
        elif op=='disable': enabled=False
        elif op=='enable': enabled=True
        elif op=='draw': out.append(sorted(clip if enabled else full))
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 4), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 4), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 4), [[0, 1, 2, 3]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 4), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 4), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 4), [[2], [0, 1, 3], [0, 1, 2, 3]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 4), [[0, 1, 2, 3]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 4), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 4), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 4), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 4), [[]])
if N == 2:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 5), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 5), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 5), [[0, 1, 2, 3, 4]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 5), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 5), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 5), [[2], [0, 1, 3, 4], [0, 1, 2, 3, 4]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 5), [[0, 1, 2, 3, 4]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 5), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 5), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 5), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 5), [[]])
if N == 3:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 6), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 6), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 6), [[0, 1, 2, 3, 4, 5]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 6), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 6), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 6), [[2], [0, 1, 3, 4, 5], [0, 1, 2, 3, 4, 5]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 6), [[0, 1, 2, 3, 4, 5]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 6), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 6), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 6), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 6), [[]])
if N == 4:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 7), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 7), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 7), [[0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 7), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 7), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 7), [[2], [0, 1, 3, 4, 5, 6], [0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 7), [[0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 7), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 7), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 7), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 7), [[]])
if N == 5:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 8), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 8), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 8), [[0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 8), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 8), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 8), [[2], [0, 1, 3, 4, 5, 6, 7], [0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 8), [[0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 8), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 8), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 8), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 8), [[]])
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 fixtureActualExpectedOutcome
explicit sequence 0[[0, 2], [0, 2]][[0, 2], [0, 1, 2]]Failed
explicit sequence 1[[1], [0]][[1], [0]]Passed
explicit sequence 2[[0, 1, 2, 3]][[0, 1, 2, 3]]Passed
explicit sequence 3[[1, 2]][[1, 2]]Passed
explicit sequence 4[[0], [0, 2]][[0], [0, 2]]Passed
explicit sequence 5[[2], [0, 1, 3], [0, 1, 2, 3]][[2], [0, 1, 3], [0, 1, 2, 3]]Passed
explicit sequence 6[[0, 1, 2, 3]][[0, 1, 2, 3]]Passed
explicit sequence 7[[]][[]]Passed
explicit sequence 8[[0, 2]][[0, 2]]Passed
explicit sequence 9[[0]][[0]]Passed
explicit sequence 10[[]][[]]Passed

SHA-256 / bc8c8e22efc15cf3e744a8feddf1b03ad0e69b0d478a076a55acc9030fa5da3e

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(commands, size):
    full=set(range(size))
    clip=set(full)
    enabled=True
    stack=[]
    out=[]
    for cmd in commands:
        op=cmd[0]
        mask=set(cmd[1]) & full if len(cmd)>1 else set()
        if op=='save': stack.append((set(clip),True))
        elif op=='restore':
            if stack: clip,enabled=stack.pop()
        elif op=='intersect': clip &= mask
        elif op=='exclude': clip -= mask
        elif op=='union': clip |= mask
        elif op=='replace': clip=set(mask)
        elif op=='invert': clip=full-clip
        elif op=='reset': clip=set(full)
        elif op=='disable': enabled=False
        elif op=='enable': enabled=True
        elif op=='draw': out.append(sorted(clip if enabled else full))
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 4), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 4), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 4), [[0, 1, 2, 3]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 4), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 4), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 4), [[2], [0, 1, 3], [0, 1, 2, 3]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 4), [[0, 1, 2, 3]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 4), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 4), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 4), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 4), [[]])
if N == 2:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 5), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 5), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 5), [[0, 1, 2, 3, 4]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 5), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 5), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 5), [[2], [0, 1, 3, 4], [0, 1, 2, 3, 4]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 5), [[0, 1, 2, 3, 4]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 5), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 5), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 5), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 5), [[]])
if N == 3:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 6), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 6), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 6), [[0, 1, 2, 3, 4, 5]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 6), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 6), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 6), [[2], [0, 1, 3, 4, 5], [0, 1, 2, 3, 4, 5]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 6), [[0, 1, 2, 3, 4, 5]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 6), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 6), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 6), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 6), [[]])
if N == 4:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 7), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 7), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 7), [[0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 7), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 7), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 7), [[2], [0, 1, 3, 4, 5, 6], [0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 7), [[0, 1, 2, 3, 4, 5, 6]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 7), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 7), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 7), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 7), [[]])
if N == 5:
    check('explicit sequence 0', solve([['replace', [0, 1, 2]], ['save'], ['exclude', [1]], ['draw'], ['restore'], ['draw']], 8), [[0, 2], [0, 1, 2]])
    check('explicit sequence 1', solve([['replace', [0]], ['save'], ['replace', [1]], ['save'], ['replace', [2]], ['restore'], ['draw'], ['restore'], ['draw']], 8), [[1], [0]])
    check('explicit sequence 2', solve([['replace', [0]], ['disable'], ['save'], ['enable'], ['restore'], ['draw']], 8), [[0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 3', solve([['replace', [1, 2]], ['disable'], ['enable'], ['draw']], 8), [[1, 2]])
    check('explicit sequence 4', solve([['replace', [0]], ['exclude', [2]], ['draw'], ['union', [0, 2]], ['draw']], 8), [[0], [0, 2]])
    check('explicit sequence 5', solve([['replace', [1]], ['replace', [2]], ['draw'], ['invert'], ['draw'], ['reset'], ['draw']], 8), [[2], [0, 1, 3, 4, 5, 6, 7], [0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 6', solve([['restore'], ['draw']], 8), [[0, 1, 2, 3, 4, 5, 6, 7]])
    check('explicit sequence 7', solve([['replace', []], ['draw']], 8), [[]])
    check('explicit sequence 8', solve([['disable'], ['replace', [0, 2, 8]], ['enable'], ['draw']], 8), [[0, 2]])
    check('explicit sequence 9', solve([['reset'], ['replace', [0]], ['draw']], 8), [[0]])
    check('explicit sequence 10', solve([['replace', []], ['disable'], ['enable'], ['draw']], 8), [[]])
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 fixtureActualExpectedOutcome
explicit sequence 0[[0, 2], [0, 1, 2]][[0, 2], [0, 1, 2]]Passed
explicit sequence 1[[1], [0]][[1], [0]]Passed
explicit sequence 2[[0]][[0, 1, 2, 3]]Failed
explicit sequence 3[[1, 2]][[1, 2]]Passed
explicit sequence 4[[0], [0, 2]][[0], [0, 2]]Passed
explicit sequence 5[[2], [0, 1, 3], [0, 1, 2, 3]][[2], [0, 1, 3], [0, 1, 2, 3]]Passed
explicit sequence 6[[0, 1, 2, 3]][[0, 1, 2, 3]]Passed
explicit sequence 7[[]][[]]Passed
explicit sequence 8[[0, 2]][[0, 2]]Passed
explicit sequence 9[[0]][[0]]Passed
explicit sequence 10[[]][[]]Passed

SHA-256 / a909c67d9a2b08f40dcf328d693bfce3757aeb8ae3bd656dbfde9d2a05200d53

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 11 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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Verification & scope

Finite one-dimensional integer sample sets model coverage state only; no geometric intersection, memory layout, GPU or graphics-standard conformance is claimed. 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 2026-09-29T14:45:08.613636+00:00.

Case digest / cf0c94e650e3b4a558fb252a91ac24b5280e291543ab03b5edde48449f1145e2