Remove bootstrap cfgs from library/ by cuviper · Pull Request #141925 · rust-lang/rust

cuviper · 2025-06-02T17:26:33Z

These cfg(bootstrap) are always false now that #119899 has landed, and likewise cfg(not(bootstrap)) is always true. Therefore, we don't need to wait for the usual stage0 bump to clean these up.

rustbot · 2025-06-02T17:26:37Z

r? @workingjubilee

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rustbot · 2025-06-02T17:26:40Z

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

bjorn3 · 2025-06-02T18:26:37Z

Can we stop allowing cfg(bootstrap) for check-cfg in the standard library?

cuviper · 2025-06-02T21:34:03Z

Good idea -- I've removed a few more places, including those explicit check-cfg, although I suspect src/bootstrap is still setting the flag too, e.g. here.

workingjubilee · 2025-06-02T22:04:34Z

allowing cfg(bootstrap) in the compiler itself might be good for obvious reasons, so probably the bootstrap allowance should stay. if we find it gets applied to std too then that can be fixed separately.

workingjubilee · 2025-06-02T22:05:01Z

Thanks!

@bors r+ rollup

bors · 2025-06-02T22:05:04Z

📌 Commit c87b072 has been approved by workingjubilee

It is now in the queue for this repository.

…kingjubilee Remove bootstrap cfgs from library/ These `cfg(bootstrap)` are always false now that rust-lang#119899 has landed, and likewise `cfg(not(bootstrap))` is always true. Therefore, we don't need to wait for the usual stage0 bump to clean these up.

Rollup of 8 pull requests Successful merges: - #137725 (Add `iter` macro) - #141455 (std: abort the process on failure to allocate a TLS key) - #141569 (Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`) - #141698 (Use the informative error as the main const eval error message) - #141925 (Remove bootstrap cfgs from library/) - #141943 (Remove pre-expansion AST stats.) - #141945 (Remove `Path::is_ident`.) - #141957 (Add missing `dyn` keywords to tests that do not test for them Part 2) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #141925 - cuviper:vestigial-bootstrap, r=workingjubilee Remove bootstrap cfgs from library/ These `cfg(bootstrap)` are always false now that #119899 has landed, and likewise `cfg(not(bootstrap))` is always true. Therefore, we don't need to wait for the usual stage0 bump to clean these up.

Rollup of 8 pull requests Successful merges: - rust-lang/rust#137725 (Add `iter` macro) - rust-lang/rust#141455 (std: abort the process on failure to allocate a TLS key) - rust-lang/rust#141569 (Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`) - rust-lang/rust#141698 (Use the informative error as the main const eval error message) - rust-lang/rust#141925 (Remove bootstrap cfgs from library/) - rust-lang/rust#141943 (Remove pre-expansion AST stats.) - rust-lang/rust#141945 (Remove `Path::is_ident`.) - rust-lang/rust#141957 (Add missing `dyn` keywords to tests that do not test for them Part 2) r? `@ghost` `@rustbot` modify labels: rollup

RalfJung · 2025-06-06T06:55:51Z

library/core/Cargo.toml

 [lints.rust.unexpected_cfgs]
 level = "warn"
 check-cfg = [
-    'cfg(bootstrap)',


Despite this removal, cfg(bootstrap) gets accepted in libcore apparently. However, it now gets rejected for out-of-tree builds, such as https://github.com/rust-lang/miri-test-libstd/. That's bad since it means we'll land changes that then fail to build elsewhere.

I think either the cfg(bootstrap) here should be added back, or our CI needs to ensure that there truly isn't any cfg(bootstrap) in libcore.

Also see https://rust-lang.zulipchat.com/#narrow/channel/269128-miri/topic/Miri.20test-libstd.20Failure.20.282025-06.29/with/522715612

Oh, that's troublesome. Sorry, I didn't realize that would happen.

That's probably because bootstrap is still adding the cfg manually to all crates.

rust/src/bootstrap/src/lib.rs

Lines 80 to 84 in d00435f

/// Extra `--check-cfg` to add when building the compiler or tools

/// (Mode restriction, config name, config values (if any))

#[expect(clippy::type_complexity)] // It's fine for hard-coded list and type is explained above.

const EXTRA_CHECK_CFGS: &[(Option<Mode>, &str, Option<&[&'static str]>)] = &[

(None, "bootstrap", None),

…kingjubilee Remove bootstrap cfgs from library/ These `cfg(bootstrap)` are always false now that rust-lang#119899 has landed, and likewise `cfg(not(bootstrap))` is always true. Therefore, we don't need to wait for the usual stage0 bump to clean these up.

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#137725 (Add `iter` macro) - rust-lang#141455 (std: abort the process on failure to allocate a TLS key) - rust-lang#141569 (Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`) - rust-lang#141698 (Use the informative error as the main const eval error message) - rust-lang#141925 (Remove bootstrap cfgs from library/) - rust-lang#141943 (Remove pre-expansion AST stats.) - rust-lang#141945 (Remove `Path::is_ident`.) - rust-lang#141957 (Add missing `dyn` keywords to tests that do not test for them Part 2) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 8 pull requests Successful merges: - rust-lang/rust#137725 (Add `iter` macro) - rust-lang/rust#141455 (std: abort the process on failure to allocate a TLS key) - rust-lang/rust#141569 (Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`) - rust-lang/rust#141698 (Use the informative error as the main const eval error message) - rust-lang/rust#141925 (Remove bootstrap cfgs from library/) - rust-lang/rust#141943 (Remove pre-expansion AST stats.) - rust-lang/rust#141945 (Remove `Path::is_ident`.) - rust-lang/rust#141957 (Add missing `dyn` keywords to tests that do not test for them Part 2) r? `@ghost` `@rustbot` modify labels: rollup

Remove bootstrap cfgs from library/

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rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 2, 2025

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Remove more library bootstrap

c87b072

cuviper force-pushed the vestigial-bootstrap branch from 8e99f2b to c87b072 Compare June 2, 2025 21:46

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 2, 2025

workingjubilee mentioned this pull request Jun 3, 2025

Rollup of 14 pull requests #141940

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workingjubilee mentioned this pull request Jun 3, 2025

Rollup of 13 pull requests #141941

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matthiaskrgr mentioned this pull request Jun 3, 2025

Rollup of 8 pull requests #141984

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bors merged commit c8a0f69 into rust-lang:master Jun 4, 2025
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RalfJung reviewed Jun 6, 2025

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RalfJung mentioned this pull request Jun 7, 2025

cfg(bootstrap) should not be allowed in library/ #142150

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GuillaumeGomez added a commit to GuillaumeGomez/rust that referenced this pull request Jun 10, 2025

Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Implement RFC 3631: add rustdoc doc_cfg features #138907

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Update to Rust 1.89.0 dtolnay/buck2-rustc-bootstrap#21

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Remove cfg(bootstrap) for doc_cfg feature following rust-lang#141925

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Toolchain upgrade to nightly-2025-10-09 flux-rs/flux#1271

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Remove bootstrap cfgs from library/#141925

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bors merged 2 commits intorust-lang:masterfrom
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	/// Extra `--check-cfg` to add when building the compiler or tools
	/// (Mode restriction, config name, config values (if any))
	#[expect(clippy::type_complexity)] // It's fine for hard-coded list and type is explained above.
	const EXTRA_CHECK_CFGS: &[(Option<Mode>, &str, Option<&[&'static str]>)] = &[
	(None, "bootstrap", None),

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