{"abstract":"The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].","category":"Container mutation","checks":4,"contract":"Clear the list in place so an existing alias observes an empty list; return [target,alias]. Inputs are the finite Python values shown by the executable fixtures; no concurrent execution is assumed.","evaluation_group":"model-e73c6a44c484180e","failed_approach":"An empty slice creates another list rather than clearing the aliased object.","family":"xr-list-clear-preserves-alias-reference","id":"FA-4376","implementations":{"attempt":{"sha256":"1ab813ebb450491f1b5a1df4f70f2aae22acd2285dcef3968e052e1d2ca37009","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    a=list(x); alias=a; a=a[:0]; return [a,alias]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('populated alias', solve(['a', 'b']), [[], []])\ncheck('singleton alias', solve(['a']), [[], []])\ncheck('already empty', solve([]), [[], []])\ncheck('duplicates', solve(['a', 'a']), [[], []])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"c267ba390e1ac0d18846b1871dc65ecbe3609a33f92ee138d141f3a5ecdc16fa","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    a=list(x); alias=a; a=[]; return [a,alias]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('populated alias', solve(['a', 'b']), [[], []])\ncheck('singleton alias', solve(['a']), [[], []])\ncheck('already empty', solve([]), [[], []])\ncheck('duplicates', solve(['a', 'a']), [[], []])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"d81f91842dfaff9ed8a99fdcc494323e6482d083322406a6d8a0f20b4454cbe3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x, y=None):\n    a=list(x); alias=a; a.clear(); return [a,alias]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('populated alias', solve(['a', 'b']), [[], []])\ncheck('singleton alias', solve(['a']), [[], []])\ncheck('already empty', solve([]), [[], []])\ncheck('duplicates', solve(['a', 'a']), [[], []])\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xr-list-clear-preserves-alias-reference","generated_at":"2026-09-29T14:37:38.493384+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.","repair":"Clear the list in place so an existing alias observes an empty list; return [target,alias].","root_cause":"Rebinding the local name leaves aliases pointing at the populated original list.","sha256":"0d391bf1c41bd694f63b65f73fe87f0ff12321b52fbf223bf0be99c890393aa9","title":"List clear preserves alias reference · case 01","variant":1,"variant_policy":"Five execution reruns of a fixed adversarial fixture suite; variant number does not alter semantic inputs.","verification":{"attempt":{"elapsed_ms":38.541,"exit_code":1,"observations":[{"actual":[[],["a","b"]],"check":"populated alias","expected":[[],[]],"passed":false},{"actual":[[],["a"]],"check":"singleton alias","expected":[[],[]],"passed":false},{"actual":[[],[]],"check":"already empty","expected":[[],[]],"passed":true},{"actual":[[],["a","a"]],"check":"duplicates","expected":[[],[]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"populated alias\", \"actual\": [[], [\"a\", \"b\"]], \"expected\": [[], []], \"passed\": false}, {\"check\": \"singleton alias\", \"actual\": [[], [\"a\"]], \"expected\": [[], []], \"passed\": false}, {\"check\": \"already empty\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"duplicates\", \"actual\": [[], [\"a\", \"a\"]], \"expected\": [[], []], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.321,"exit_code":1,"observations":[{"actual":[[],["a","b"]],"check":"populated alias","expected":[[],[]],"passed":false},{"actual":[[],["a"]],"check":"singleton alias","expected":[[],[]],"passed":false},{"actual":[[],[]],"check":"already empty","expected":[[],[]],"passed":true},{"actual":[[],["a","a"]],"check":"duplicates","expected":[[],[]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"populated alias\", \"actual\": [[], [\"a\", \"b\"]], \"expected\": [[], []], \"passed\": false}, {\"check\": \"singleton alias\", \"actual\": [[], [\"a\"]], \"expected\": [[], []], \"passed\": false}, {\"check\": \"already empty\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"duplicates\", \"actual\": [[], [\"a\", \"a\"]], \"expected\": [[], []], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":37.889,"exit_code":0,"observations":[{"actual":[[],[]],"check":"populated alias","expected":[[],[]],"passed":true},{"actual":[[],[]],"check":"singleton alias","expected":[[],[]],"passed":true},{"actual":[[],[]],"check":"already empty","expected":[[],[]],"passed":true},{"actual":[[],[]],"check":"duplicates","expected":[[],[]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"populated alias\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"singleton alias\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"already empty\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}, {\"check\": \"duplicates\", \"actual\": [[], []], \"expected\": [[], []], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}