uutils/coreutils

Date rejects valid large years that GNU date accepts

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#9,774 opened on Dec 22, 2025

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U - datefuzzinggood first issue

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Description

GNU:

  $ LANG=C TZ=UTC0 /usr/bin/date -d "18978-01-01"
  Thu Jan  1 00:00:00 UTC 18978

Rust:

  $ LANG=C TZ=UTC0 ./target/debug/date -d "18978-01-01"
  date: invalid date '18978-01-01'
  • GNU date: Accepts year 18978 and outputs the date correctly
  • Rust date: Rejects year 18978 as invalid date, appears to have a limit around year 9999
  • GNU date supports much larger year ranges than our implementation

Found with a fuzzer

Contributor guide

Research direction
Identify the date parsing code that limits years to 9999 and extend it to handle larger years like 18978.
Tech stack
rust
Domain
cli
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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
Rust
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75