FA-3091 / Regular expressions / Open access

One tag match consumes neighboring tags · case 01

One tag match consumes neighboring tags.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Extract each nonnested angle-bracket body; fixtures contain no brackets inside a body.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Extract each nonnested angle-bracket body; fixtures contain no brackets inside a body.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Extract each nonnested angle-bracket body; fixtures contain no brackets inside a body.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'<(.*)>',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('<a><b>'), ['a', 'b'])
check('boundary 2', solve('<>'), [''])
check('boundary 3', solve('x<c>y'), ['c'])
check('boundary 4', solve('none'), [])
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
boundary 1	`['a><b']`	`['a', 'b']`	Failed
boundary 2	`['']`	`['']`	Passed
boundary 3	`['c']`	`['c']`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / a5db4766c1225657a4d0b834459b24b8011ffd86587e653e86228c20d13393df

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'<(.+?)>',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('<a><b>'), ['a', 'b'])
check('boundary 2', solve('<>'), [''])
check('boundary 3', solve('x<c>y'), ['c'])
check('boundary 4', solve('none'), [])
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
boundary 1	`['a', 'b']`	`['a', 'b']`	Passed
boundary 2	`[]`	`['']`	Failed
boundary 3	`['c']`	`['c']`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / e7fd761d24009a506eabf15603598961d9031f7b1ef3cb4b34b74780d4157fbb

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'<([^<>]*)>',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('<a><b>'), ['a', 'b'])
check('boundary 2', solve('<>'), [''])
check('boundary 3', solve('x<c>y'), ['c'])
check('boundary 4', solve('none'), [])
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
boundary 1	`['a', 'b']`	`['a', 'b']`	Passed
boundary 2	`['']`	`['']`	Passed
boundary 3	`['c']`	`['c']`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / ca3c940a184a0656d50ca548d762dc710c7d1d9a81ea916251f0d1993fca5868

Verification & scope

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 2026-09-29T14:37:21.351509+00:00.

Case digest / 2431c1baef3e06644b5afe65d4b94505e4edb50383cd50b92189f7f6c2f1522c