FA-3111 / Regular expressions / Open access

Unicode word characters alter ASCII identifier boundaries · case 01

Unicode word characters alter ASCII identifier boundaries.

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 ASCII word runs using ASCII word and boundary semantics.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Extract ASCII word runs using ASCII word and boundary semantics.

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

Case contract

Extract ASCII word runs using ASCII word and boundary semantics.

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'\b[A-Za-z0-9_]+\b',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('éabc'), ['abc'])
check('boundary 2', solve('a_b'), ['a_b'])
check('boundary 3', solve('中42'), ['42'])
check('boundary 4', solve('!'), [])
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	`[]`	`['abc']`	Failed
boundary 2	`['a_b']`	`['a_b']`	Passed
boundary 3	`[]`	`['42']`	Failed
boundary 4	`[]`	`[]`	Passed

SHA-256 / 8d6e1fc69a85eb1a6b40ba16eab4ea6df192fb9f842ef0176e4dd8ee69294fb2

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'\w+',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('éabc'), ['abc'])
check('boundary 2', solve('a_b'), ['a_b'])
check('boundary 3', solve('中42'), ['42'])
check('boundary 4', solve('!'), [])
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	`['éabc']`	`['abc']`	Failed
boundary 2	`['a_b']`	`['a_b']`	Passed
boundary 3	`['中42']`	`['42']`	Failed
boundary 4	`[]`	`[]`	Passed

SHA-256 / d3ab1d8b251a3754c452177ed8136958275cd8fee0c0ce6cfdc9fa8010de523d

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'\b\w+\b',x,re.ASCII)
    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('éabc'), ['abc'])
check('boundary 2', solve('a_b'), ['a_b'])
check('boundary 3', solve('中42'), ['42'])
check('boundary 4', solve('!'), [])
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	`['abc']`	`['abc']`	Passed
boundary 2	`['a_b']`	`['a_b']`	Passed
boundary 3	`['42']`	`['42']`	Passed
boundary 4	`[]`	`[]`	Passed

SHA-256 / 01fac8869c26587a063b141dc48d4c4bbd281bb4eb0b2746ed98a46e7f213cb6

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 2026-09-29T14:37:21.626172+00:00.

Case digest / 28fffd922cc847eb1c92d8c9dc1dfe77bbec01d7768f7db594f0af95782c200f