Ubuntu 18.04预装rustc 1.18而非1.21的原因及是否建议调整

Great question—this kind of version discrepancy in Ubuntu releases often boils down to the distro's core policies and dependency management. Let’s unpack the details:

Why the Rustc Version "Downgraded" in Ubuntu 18.04 #

• LTS Stability & Freeze Policies: Ubuntu 18.04 is a Long-Term Support (LTS) release, which prioritizes stability over cutting-edge software. The release has a strict feature freeze window several months before launch—if rustc 1.18 was the most recent stable, thoroughly tested version available when the freeze hit, maintainers would lock it in. Non-LTS releases (like versions <18.04) have shorter support cycles and looser freeze rules, so they could adopt rustc 1.21 after it launched without breaking the release timeline.
• Dependency Chain Compatibility: Ubuntu’s package ecosystem is deeply interconnected. Upgrading rustc to a newer version might break other pre-installed software that relies on specific APIs or behavior from 1.18. Maintainers avoid making such changes late in the release cycle to prevent widespread compatibility issues.

Is It Worth Suggesting an Adjustment Before Official Release? #

Absolutely—here’s why:

• Critical Software Requirements: You noted that recent Firefox versions require at least rustc 1.23 (I assume that’s a typo for 1.23 instead of 2.23). If Ubuntu 18.04 ships with 1.18, users who want to compile the latest Firefox (or other Rust-dependent software) will hit immediate roadblocks, even if they use the distro’s official tools.
• User Experience Impact: For developers and power users relying on Rust, having an outdated system-wide rustc version creates unnecessary friction. While tools like rustup can work around this, the default system package should ideally meet common modern use cases.

If you submit a suggestion to the Ubuntu package maintainers, framing it around critical dependency needs (like Firefox compatibility) will make it more likely to be considered before the final release.

内容的提问来源于stack exchange，提问作者Kalle Richter