compiler: Fix a couple issues around cargo feature unification #148341

jyn514 · 2025-10-31T18:22:23Z

cc #148266. this doesn't fix all the issues (rustc_public and rustc_transmute still emit warnings when tested individually), but it fixes all the simple ones.

To fix rustc_public I will probably need help from @AlexanderPortland or @makai410 to make sure I am not accidentally cfg-ing out items that are meant to be public. To fix rustc_transmute, I will need to know (from @jswrenn ?) in what context the rustc cargo feature is disapled. To reproduce the issues, you can run x test rustc_{transmute,public} locally.

The first issue I fixed was a warning in rustc_index:

Testing stage2 {rustc_parse_format} (aarch64-apple-darwin)
   Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index)
error: extern crate `smallvec` is unused in crate `rustc_index`
 --> compiler/rustc_index/src/lib.rs:2:1
  |
2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))]
  | ^
  |
  = help: remove the dependency or add `use smallvec as _;` to the crate root
  = note: `-D unused-crate-dependencies` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]`

error: could not compile `rustc_index` (lib) due to 1 previous error

The second was that type_ir_macros didn't fully specify its dependencies:

Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin)
   Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros)
error[E0432]: unresolved import `syn::visit_mut`
   --> compiler/rustc_type_ir_macros/src/lib.rs:2:10
    |
  2 | use syn::visit_mut::VisitMut;
    |          ^^^^^^^^^ could not find `visit_mut` in `syn`
    |
note: found an item that was configured out
   --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21
    |
878 | #[cfg(feature = "visit-mut")]
    |       --------------------- the item is gated behind the `visit-mut` feature
879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))]
880 | pub use crate::gen::visit_mut;
    |                     ^^^^^^^^^

error[E0433]: failed to resolve: could not find `visit_mut` in `syn`
   --> compiler/rustc_type_ir_macros/src/lib.rs:206:18
    |
206 |             syn::visit_mut::visit_type_path_mut(self, i);
    |                  ^^^^^^^^^ could not find `visit_mut` in `syn`
    |
note: found an item that was configured out
   --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21
    |
878 | #[cfg(feature = "visit-mut")]
    |       --------------------- the item is gated behind the `visit-mut` feature
879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))]
880 | pub use crate::gen::visit_mut;
    |                     ^^^^^^^^^

The first was a warning: ``` Testing stage2 {rustc_parse_format} (aarch64-apple-darwin) Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index) error: extern crate `smallvec` is unused in crate `rustc_index` --> compiler/rustc_index/src/lib.rs:2:1 | 2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))] | ^ | = help: remove the dependency or add `use smallvec as _;` to the crate root = note: `-D unused-crate-dependencies` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]` error: could not compile `rustc_index` (lib) due to 1 previous error ``` The second was that `type_ir_macros` didn't fully specify its dependencies: ``` Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin) Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros) error[E0432]: unresolved import `syn::visit_mut` --> compiler/rustc_type_ir_macros/src/lib.rs:2:10 | 2 | use syn::visit_mut::VisitMut; | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ error[E0433]: failed to resolve: could not find `visit_mut` in `syn` --> compiler/rustc_type_ir_macros/src/lib.rs:206:18 | 206 | syn::visit_mut::visit_type_path_mut(self, i); | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ ```

rustbot · 2025-10-31T18:22:28Z

r? @BoxyUwU

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jyn514 · 2025-10-31T18:32:36Z

ohai boxy

makai410 · 2025-11-01T08:33:19Z

I've done the rustc_public part in #148358 .

BoxyUwU · 2025-11-04T15:56:27Z

@bors r+ rollup

BoxyUwU · 2025-11-04T15:56:30Z

hi jyn

bors · 2025-11-04T15:56:30Z

📌 Commit 60c230b has been approved by BoxyUwU

It is now in the queue for this repository.

bors · 2025-11-04T15:56:31Z

🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened.

compiler: Fix a couple issues around cargo feature unification cc rust-lang#148266. this doesn't fix all the issues (`rustc_public` and `rustc_transmute` still emit warnings when tested individually), but it fixes all the simple ones. To fix rustc_public I will probably need help from `@AlexanderPortland` or `@makai410` to make sure I am not accidentally cfg-ing out items that are meant to be public. To fix `rustc_transmute`, I will need to know (from `@jswrenn` ?) in what context the `rustc` cargo feature is disapled. To reproduce the issues, you can run `x test rustc_{transmute,public}` locally. --- The first issue I fixed was a warning in `rustc_index`: ``` Testing stage2 {rustc_parse_format} (aarch64-apple-darwin) Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index) error: extern crate `smallvec` is unused in crate `rustc_index` --> compiler/rustc_index/src/lib.rs:2:1 | 2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))] | ^ | = help: remove the dependency or add `use smallvec as _;` to the crate root = note: `-D unused-crate-dependencies` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]` error: could not compile `rustc_index` (lib) due to 1 previous error ``` The second was that `type_ir_macros` didn't fully specify its dependencies: ``` Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin) Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros) error[E0432]: unresolved import `syn::visit_mut` --> compiler/rustc_type_ir_macros/src/lib.rs:2:10 | 2 | use syn::visit_mut::VisitMut; | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ error[E0433]: failed to resolve: could not find `visit_mut` in `syn` --> compiler/rustc_type_ir_macros/src/lib.rs:206:18 | 206 | syn::visit_mut::visit_type_path_mut(self, i); | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ ```

compiler: Fix a couple issues around cargo feature unification cc rust-lang#148266. this doesn't fix all the issues (`rustc_public` and `rustc_transmute` still emit warnings when tested individually), but it fixes all the simple ones. To fix rustc_public I will probably need help from ``@AlexanderPortland`` or ``@makai410`` to make sure I am not accidentally cfg-ing out items that are meant to be public. To fix `rustc_transmute`, I will need to know (from ``@jswrenn`` ?) in what context the `rustc` cargo feature is disapled. To reproduce the issues, you can run `x test rustc_{transmute,public}` locally. --- The first issue I fixed was a warning in `rustc_index`: ``` Testing stage2 {rustc_parse_format} (aarch64-apple-darwin) Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index) error: extern crate `smallvec` is unused in crate `rustc_index` --> compiler/rustc_index/src/lib.rs:2:1 | 2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))] | ^ | = help: remove the dependency or add `use smallvec as _;` to the crate root = note: `-D unused-crate-dependencies` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]` error: could not compile `rustc_index` (lib) due to 1 previous error ``` The second was that `type_ir_macros` didn't fully specify its dependencies: ``` Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin) Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros) error[E0432]: unresolved import `syn::visit_mut` --> compiler/rustc_type_ir_macros/src/lib.rs:2:10 | 2 | use syn::visit_mut::VisitMut; | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ error[E0433]: failed to resolve: could not find `visit_mut` in `syn` --> compiler/rustc_type_ir_macros/src/lib.rs:206:18 | 206 | syn::visit_mut::visit_type_path_mut(self, i); | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ ```

compiler: Fix a couple issues around cargo feature unification cc rust-lang#148266. this doesn't fix all the issues (`rustc_public` and `rustc_transmute` still emit warnings when tested individually), but it fixes all the simple ones. To fix rustc_public I will probably need help from ```@AlexanderPortland``` or ```@makai410``` to make sure I am not accidentally cfg-ing out items that are meant to be public. To fix `rustc_transmute`, I will need to know (from ```@jswrenn``` ?) in what context the `rustc` cargo feature is disapled. To reproduce the issues, you can run `x test rustc_{transmute,public}` locally. --- The first issue I fixed was a warning in `rustc_index`: ``` Testing stage2 {rustc_parse_format} (aarch64-apple-darwin) Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index) error: extern crate `smallvec` is unused in crate `rustc_index` --> compiler/rustc_index/src/lib.rs:2:1 | 2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))] | ^ | = help: remove the dependency or add `use smallvec as _;` to the crate root = note: `-D unused-crate-dependencies` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]` error: could not compile `rustc_index` (lib) due to 1 previous error ``` The second was that `type_ir_macros` didn't fully specify its dependencies: ``` Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin) Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros) error[E0432]: unresolved import `syn::visit_mut` --> compiler/rustc_type_ir_macros/src/lib.rs:2:10 | 2 | use syn::visit_mut::VisitMut; | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ error[E0433]: failed to resolve: could not find `visit_mut` in `syn` --> compiler/rustc_type_ir_macros/src/lib.rs:206:18 | 206 | syn::visit_mut::visit_type_path_mut(self, i); | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ ```

Rollup of 5 pull requests Successful merges: - #145314 (Tweak output of missing lifetime on associated type) - #147803 (Add -Zannotate-moves for profiler visibility of move/copy operations (codegen)) - #147925 (Fix tests for big-endian) - #148341 (compiler: Fix a couple issues around cargo feature unification) - #148371 (Dogfood `trim_{suffix|prefix}` in compiler) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 6 pull requests Successful merges: - #147355 (Add alignment parameter to `simd_masked_{load,store}`) - #147925 (Fix tests for big-endian) - #148341 (compiler: Fix a couple issues around cargo feature unification) - #148371 (Dogfood `trim_{suffix|prefix}` in compiler) - #148495 (Implement Path::is_empty) - #148502 (rustc-dev-guide subtree update) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #148341 - jyn514:feature-unification, r=BoxyUwU compiler: Fix a couple issues around cargo feature unification cc #148266. this doesn't fix all the issues (`rustc_public` and `rustc_transmute` still emit warnings when tested individually), but it fixes all the simple ones. To fix rustc_public I will probably need help from ````@AlexanderPortland```` or ````@makai410```` to make sure I am not accidentally cfg-ing out items that are meant to be public. To fix `rustc_transmute`, I will need to know (from ````@jswrenn```` ?) in what context the `rustc` cargo feature is disapled. To reproduce the issues, you can run `x test rustc_{transmute,public}` locally. --- The first issue I fixed was a warning in `rustc_index`: ``` Testing stage2 {rustc_parse_format} (aarch64-apple-darwin) Compiling rustc_index v0.0.0 (/Users/ci/project/compiler/rustc_index) error: extern crate `smallvec` is unused in crate `rustc_index` --> compiler/rustc_index/src/lib.rs:2:1 | 2 | #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))] | ^ | = help: remove the dependency or add `use smallvec as _;` to the crate root = note: `-D unused-crate-dependencies` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unused_crate_dependencies)]` error: could not compile `rustc_index` (lib) due to 1 previous error ``` The second was that `type_ir_macros` didn't fully specify its dependencies: ``` Testing stage1 {rustc_type_ir_macros} (aarch64-apple-darwin) Compiling rustc_type_ir_macros v0.0.0 (/Users/jyn/src/ferrocene3/compiler/rustc_type_ir_macros) error[E0432]: unresolved import `syn::visit_mut` --> compiler/rustc_type_ir_macros/src/lib.rs:2:10 | 2 | use syn::visit_mut::VisitMut; | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ error[E0433]: failed to resolve: could not find `visit_mut` in `syn` --> compiler/rustc_type_ir_macros/src/lib.rs:206:18 | 206 | syn::visit_mut::visit_type_path_mut(self, i); | ^^^^^^^^^ could not find `visit_mut` in `syn` | note: found an item that was configured out --> /Users/jyn/.local/lib/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/syn-2.0.106/src/lib.rs:880:21 | 878 | #[cfg(feature = "visit-mut")] | --------------------- the item is gated behind the `visit-mut` feature 879 | #[cfg_attr(docsrs, doc(cfg(feature = "visit-mut")))] 880 | pub use crate::gen::visit_mut; | ^^^^^^^^^ ```

Rollup of 6 pull requests Successful merges: - rust-lang/rust#147355 (Add alignment parameter to `simd_masked_{load,store}`) - rust-lang/rust#147925 (Fix tests for big-endian) - rust-lang/rust#148341 (compiler: Fix a couple issues around cargo feature unification) - rust-lang/rust#148371 (Dogfood `trim_{suffix|prefix}` in compiler) - rust-lang/rust#148495 (Implement Path::is_empty) - rust-lang/rust#148502 (rustc-dev-guide subtree update) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned BoxyUwU Oct 31, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 31, 2025

makai410 mentioned this pull request Nov 1, 2025

Fix some issues around rustc_public #148358

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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 Nov 4, 2025

matthiaskrgr mentioned this pull request Nov 4, 2025

Rollup of 4 pull requests #148485

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matthiaskrgr mentioned this pull request Nov 4, 2025

Rollup of 3 pull requests #148489

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matthiaskrgr mentioned this pull request Nov 4, 2025

Rollup of 5 pull requests #148496

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Zalathar mentioned this pull request Nov 4, 2025

Rollup of 6 pull requests #148507

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bors merged commit cc1d776 into rust-lang:master Nov 5, 2025
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rustbot added this to the 1.93.0 milestone Nov 5, 2025

jyn514 deleted the feature-unification branch November 5, 2025 22:14

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