tursodatabase/turso

Fuzzer failure in math_expression_fuzz_run_mvcc with trigonometry functions

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#5,165 opened on Feb 11, 2026

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Description

[78](https://github.com/tursodatabase/turso/actions/runs/21879378973/job/63157240521?pr=4999#step:11:179)

    thread 'fuzz_tests::math_expression_fuzz_run_mvcc' panicked at tests/fuzz/mod.rs:4337:21:
    query: SELECT (trunc(atanh((tanh(0.0 - 2.0) + mod(2.0, 2.0) * (-2.0 - 0.0))))) + -2.0, limbo: -3.0, sqlite: -4.0 seed: 1770752065271

https://github.com/tursodatabase/turso/actions/runs/21879378973/job/63157240521?pr=4999

Contributor guide

Research direction
Reproduce the failing fuzz test locally by running the specific seed (1770752065271) and trace the execution of the math expression through the SQL parser, validator, and executor. Compare the result with SQLite's result to identify where the discrepancy occurs. Focus on the implementation of `atanh`, `tanh`, `trunc`, and `mod` functions.
Tech stack
rust
Domain
database
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Rustfuzzing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40