{
  "$type": "site.standard.document",
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  "path": "/t/why-is-rustc-bootstrap-so-actively-discouraged/24123#post_6",
  "publishedAt": "2026-04-01T14:13:08.000Z",
  "site": "https://internals.rust-lang.org",
  "tags": [
    "common pasture"
  ],
  "textContent": "MusicalNinjaDad:\n\n> Yes, but why does that argument not hold just the same for nightly (also not available on a per-crate basis) where the breakage could happen every 24 hours, not every 6 weeks?\n\nFirst of all, it is your choice how often you update the nightly version you use or support for your project. Nobody forces you to update every 24 hours.\n\nAlso, if you use stable, then things are very unlikely to break every 6 weeks. We spend a lot of effort on that. But if any of your dependencies uses unstable features, the risk of breakage increases dramatically. Therefore it is very important that you as application developer know whether any _transitive_ dependency needs unstable features. But anyway that hole in the Rust stability story has been fixed so this is not a concern any more.\n\n* * *\n\nTo answer the original question -- there is a non-trivial social contract around RUSTC_BOOTSTRAP. Using it responsibly comes with a bunch of obligations to the party that enables this flag. If it gets overused, that is very likely to do enormous damage to the Rust ecosystem. We _need_ the freedom to iterate on unstable features, including breaking changes, without the overhead of deprecation periods and future-compatibility cycles. If a sufficiently large part of the ecosystem breaks when we do that, we effectively lose that freedom, which is very bad news for Rust language development. We strongly discourage its use because we want to avoid that damage.\n\nSo, why should you not use RUSTC_BOOTSTRAP? For the same reason that you shouldn't let your cows overfeed on the common pasture.",
  "title": "Why is `RUSTC_BOOTSTRAP` so actively discouraged?"
}