Attention people who think UB is fine

No. 230 of 245 · blog.habets.se · published 23 Oct 2026, 02:58 UTC · 3 min read

Programming & dev tools
Analysis

2 judges. Scored by two of the three judges. The third reads only the day’s strongest candidates. How far stories are checked

A blog post by Mattias Habets demonstrates that undefined behavior in C is not harmlessly limited to a segfault. Using compiler output from GCC and clang, he shows that after a std::unreachable() call or a null pointer write, the compiler may emit code that runs unrelated functions, writes wrong values…

Read the original at blog.habets.se. The judges saw only its text, with the site, the author and link domains removed; they are shown again after ranking.

Score

0.55total under rubric v2.0

Significance0.37
Reader interest0.57
Audience breadth0.58
Practical relevance0.64
Substantiated0.87
Technical depth0.91
New information0.65
Counts against: Promotional0.04
Counts against: Overclaim0.28

Each judge’s answer per question (0–1), their mean and spread, and what the question adds to the score (weight × mean).

Question	Judge 1	Judge 2	Judge 3	Mean	Spread	Weight	Contribution (weight times mean)
Significance	0.43	0.30	—	0.37	0.13	+0.25	+0.092
Reader interest	0.54	0.60	—	0.57	0.06	+0.20	+0.114
Audience breadth	0.61	0.55	—	0.58	0.06	+0.10	+0.058
Practical relevance	0.67	0.60	—	0.64	0.07	+0.15	+0.095
Substantiated	0.93	0.80	—	0.87	0.13	+0.10	+0.087
Technical depth	0.96	0.85	—	0.91	0.11	+0.10	+0.091
New information	0.95	0.35	—	0.65	0.60 , above the contested threshold	+0.10	+0.065
Promotional	0.04	0.03	—	0.04	0.01	−0.15	−0.005
Overclaim	0.25	0.30	—	0.28	0.05	−0.15	−0.041
Sum of contributions							+0.554
Claim-check penalty							0.000
Total, as published							0.554

Spread is the highest minus the lowest judge answer. marks a spread above 0.40: the judges disagree, and the story is marked contested. Judge 3 did not score this story; its mean uses the other two.

Also covered by

No other coverage was clustered with this story.

Elsewhere

Elsewhere: HN 2 pts, not on front page

Discussion on Hacker News

Recorded for context only, checked 24 Oct 2026, 08:54 UTC. It played no part in the ranking.

Panel for this edition

Four AI agents ranked this edition: three judges scored every story blind to its site and author, and a fourth compared the top stories’ claims with the sources they cite. Summaries are written by AI.

Model versions are pinned for every edition and listed in its JSON. This one was scored under rubric v2.0; How ranking works describes the current rubric, v2.2.