rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names by IntegralPilot · Pull Request #148279 · rust-lang/rust

IntegralPilot · 2025-10-30T06:39:05Z

Resolves#148275 by preventing name collisions in the #[bench] macro.

Previously, a user-defined function named "b" could not be benchmarked because
the macro-generated lambda identity collided with the same name. We now generate
the lambda ident as __bench_<function_name>, ensuring it is always distinct
from the user’s function.

Because the prefix is applied recursively (e.g. benchmarking __bench_b
produces a lambda ident __bench___bench_b), there is no possible function
name that can equal its corresponding lambda ident. This guarantees that
the user can safely bench a function of any valid name without risk of
identifier collision.

rustbot · 2025-10-30T06:39:09Z

r? @jackh726

rustbot has assigned @jackh726.
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hkBst

LGTM except for a small style nit as mentioned above.

View changes since this review

oli-obk · 2025-10-31T08:19:33Z

r? hkBst

rustbot · 2025-10-31T08:19:36Z

Failed to set assignee to hkBst: invalid assignee

Note: Only org members with at least the repository "read" role, users with write permissions, or people who have commented on the PR may be assigned.

oli-obk · 2025-10-31T08:19:48Z

oh heh

@bors delegate=hkBst

bors · 2025-10-31T08:19:52Z

✌️ @hkBst, you can now approve this pull request!

If @oli-obk told you to "r=me" after making some further change, please make that change, then do @bors r=@oli-obk

hkBst · 2025-11-07T12:25:16Z

Looks fine now, but please squash your commits.

… user-defined function names

rustbot · 2025-11-08T04:39:26Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

IntegralPilot · 2025-11-08T04:43:56Z

@hkBst, just squashed the commits! Thanks again for your review & help :)

hkBst · 2025-11-08T06:47:54Z

@bors r=@hkBst

bors · 2025-11-08T06:47:57Z

📌 Commit 67802e0 has been approved by hkBst

It is now in the queue for this repository.

rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names Resolvesrust-lang#148275 by preventing name collisions in the `#[bench]` macro. Previously, a user-defined function named "b" could not be benchmarked because the macro-generated lambda identity collided with the same name. We now generate the lambda ident as `__bench_<function_name>`, ensuring it is always distinct from the user’s function. Because the prefix is applied recursively (e.g. benchmarking `__bench_b` produces a lambda ident `__bench___bench_b`), there is no possible function name that can equal its corresponding lambda ident. This guarantees that the user can safely bench a function of any valid name without risk of identifier collision.

Rollup of 16 pull requests Successful merges: - #147534 (Implement SIMD funnel shifts in const-eval/Miri) - #147686 (update isolate_highest_one for NonZero<T>) - #148020 (Show backtrace on allocation failures when possible) - #148204 (Modify contributor email entries in .mailmap) - #148230 (rustdoc: Properly highlight shebang, frontmatter & weak keywords in source code pages and code blocks) - #148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - #148555 (Fix rust-by-example spanish translation) - #148556 (Fix suggestion for returning async closures) - #148585 ([rustdoc] Replace `print` methods with functions to improve code readability) - #148600 (re-use `self.get_all_attrs` result for pass indirectly attribute) - #148612 (Add note for identifier with attempted hygiene violation) - #148613 (Switch hexagon targets to rust-lld) - #148619 (Enable std locking functions on AIX) - #148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - #148649 (don't completely reset `HeadUsages`) - #148675 (Remove eslint-js from npm dependencies) r? `@ghost` `@rustbot` modify labels: rollup

rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names Resolvesrust-lang#148275 by preventing name collisions in the `#[bench]` macro. Previously, a user-defined function named "b" could not be benchmarked because the macro-generated lambda identity collided with the same name. We now generate the lambda ident as `__bench_<function_name>`, ensuring it is always distinct from the user’s function. Because the prefix is applied recursively (e.g. benchmarking `__bench_b` produces a lambda ident `__bench___bench_b`), there is no possible function name that can equal its corresponding lambda ident. This guarantees that the user can safely bench a function of any valid name without risk of identifier collision.

Rollup of 22 pull requests Successful merges: - #128666 (Add `overflow_checks` intrinsic) - #146305 (Add correct suggestion for multi-references for self type in method) - #147179 ([DebugInfo] Fix container types failing to find template args) - #147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - #148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - #148084 (Optimize path components iteration on platforms that don't have prefixes) - #148126 (Fix rust stdlib build failing for VxWorks) - #148204 (Modify contributor email entries in .mailmap) - #148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - #148333 (constify result unwrap unchecked) - #148539 (Add Allocator proxy impls for Box, Rc, and Arc) - #148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - #148612 (Add note for identifier with attempted hygiene violation) - #148613 (Switch hexagon targets to rust-lld) - #148619 (Enable std locking functions on AIX) - #148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - #148649 (don't completely reset `HeadUsages`) - #148673 (Remove a remnant of `dyn*` from the parser) - #148675 (Remove eslint-js from npm dependencies) - #148680 (Recover `[T: N]` as `[T; N]`) - #148688 (Remove unused argument `features` from `eval_config_entry`) - #148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #148279 - IntegralPilot:master, r=hkBst rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names Resolves#148275 by preventing name collisions in the `#[bench]` macro. Previously, a user-defined function named "b" could not be benchmarked because the macro-generated lambda identity collided with the same name. We now generate the lambda ident as `__bench_<function_name>`, ensuring it is always distinct from the user’s function. Because the prefix is applied recursively (e.g. benchmarking `__bench_b` produces a lambda ident `__bench___bench_b`), there is no possible function name that can equal its corresponding lambda ident. This guarantees that the user can safely bench a function of any valid name without risk of identifier collision.

Rollup of 22 pull requests Successful merges: - rust-lang/rust#128666 (Add `overflow_checks` intrinsic) - rust-lang/rust#146305 (Add correct suggestion for multi-references for self type in method) - rust-lang/rust#147179 ([DebugInfo] Fix container types failing to find template args) - rust-lang/rust#147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - rust-lang/rust#148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - rust-lang/rust#148084 (Optimize path components iteration on platforms that don't have prefixes) - rust-lang/rust#148126 (Fix rust stdlib build failing for VxWorks) - rust-lang/rust#148204 (Modify contributor email entries in .mailmap) - rust-lang/rust#148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - rust-lang/rust#148333 (constify result unwrap unchecked) - rust-lang/rust#148539 (Add Allocator proxy impls for Box, Rc, and Arc) - rust-lang/rust#148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - rust-lang/rust#148612 (Add note for identifier with attempted hygiene violation) - rust-lang/rust#148613 (Switch hexagon targets to rust-lld) - rust-lang/rust#148619 (Enable std locking functions on AIX) - rust-lang/rust#148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - rust-lang/rust#148649 (don't completely reset `HeadUsages`) - rust-lang/rust#148673 (Remove a remnant of `dyn*` from the parser) - rust-lang/rust#148675 (Remove eslint-js from npm dependencies) - rust-lang/rust#148680 (Recover `[T: N]` as `[T; N]`) - rust-lang/rust#148688 (Remove unused argument `features` from `eval_config_entry`) - rust-lang/rust#148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names Resolvesrust-lang#148275 by preventing name collisions in the `#[bench]` macro. Previously, a user-defined function named "b" could not be benchmarked because the macro-generated lambda identity collided with the same name. We now generate the lambda ident as `__bench_<function_name>`, ensuring it is always distinct from the user’s function. Because the prefix is applied recursively (e.g. benchmarking `__bench_b` produces a lambda ident `__bench___bench_b`), there is no possible function name that can equal its corresponding lambda ident. This guarantees that the user can safely bench a function of any valid name without risk of identifier collision.

Rollup of 22 pull requests Successful merges: - rust-lang#128666 (Add `overflow_checks` intrinsic) - rust-lang#146305 (Add correct suggestion for multi-references for self type in method) - rust-lang#147179 ([DebugInfo] Fix container types failing to find template args) - rust-lang#147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - rust-lang#148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - rust-lang#148084 (Optimize path components iteration on platforms that don't have prefixes) - rust-lang#148126 (Fix rust stdlib build failing for VxWorks) - rust-lang#148204 (Modify contributor email entries in .mailmap) - rust-lang#148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - rust-lang#148333 (constify result unwrap unchecked) - rust-lang#148539 (Add Allocator proxy impls for Box, Rc, and Arc) - rust-lang#148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - rust-lang#148612 (Add note for identifier with attempted hygiene violation) - rust-lang#148613 (Switch hexagon targets to rust-lld) - rust-lang#148619 (Enable std locking functions on AIX) - rust-lang#148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - rust-lang#148649 (don't completely reset `HeadUsages`) - rust-lang#148673 (Remove a remnant of `dyn*` from the parser) - rust-lang#148675 (Remove eslint-js from npm dependencies) - rust-lang#148680 (Recover `[T: N]` as `[T; N]`) - rust-lang#148688 (Remove unused argument `features` from `eval_config_entry`) - rust-lang#148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 22 pull requests Successful merges: - rust-lang/rust#128666 (Add `overflow_checks` intrinsic) - rust-lang/rust#146305 (Add correct suggestion for multi-references for self type in method) - rust-lang/rust#147179 ([DebugInfo] Fix container types failing to find template args) - rust-lang/rust#147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - rust-lang/rust#148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - rust-lang/rust#148084 (Optimize path components iteration on platforms that don't have prefixes) - rust-lang/rust#148126 (Fix rust stdlib build failing for VxWorks) - rust-lang/rust#148204 (Modify contributor email entries in .mailmap) - rust-lang/rust#148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - rust-lang/rust#148333 (constify result unwrap unchecked) - rust-lang/rust#148539 (Add Allocator proxy impls for Box, Rc, and Arc) - rust-lang/rust#148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - rust-lang/rust#148612 (Add note for identifier with attempted hygiene violation) - rust-lang/rust#148613 (Switch hexagon targets to rust-lld) - rust-lang/rust#148619 (Enable std locking functions on AIX) - rust-lang/rust#148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - rust-lang/rust#148649 (don't completely reset `HeadUsages`) - rust-lang/rust#148673 (Remove a remnant of `dyn*` from the parser) - rust-lang/rust#148675 (Remove eslint-js from npm dependencies) - rust-lang/rust#148680 (Recover `[T: N]` as `[T; N]`) - rust-lang/rust#148688 (Remove unused argument `features` from `eval_config_entry`) - rust-lang/rust#148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 22 pull requests Successful merges: - rust-lang#128666 (Add `overflow_checks` intrinsic) - rust-lang#146305 (Add correct suggestion for multi-references for self type in method) - rust-lang#147179 ([DebugInfo] Fix container types failing to find template args) - rust-lang#147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - rust-lang#148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - rust-lang#148084 (Optimize path components iteration on platforms that don't have prefixes) - rust-lang#148126 (Fix rust stdlib build failing for VxWorks) - rust-lang#148204 (Modify contributor email entries in .mailmap) - rust-lang#148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - rust-lang#148333 (constify result unwrap unchecked) - rust-lang#148539 (Add Allocator proxy impls for Box, Rc, and Arc) - rust-lang#148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - rust-lang#148612 (Add note for identifier with attempted hygiene violation) - rust-lang#148613 (Switch hexagon targets to rust-lld) - rust-lang#148619 (Enable std locking functions on AIX) - rust-lang#148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - rust-lang#148649 (don't completely reset `HeadUsages`) - rust-lang#148673 (Remove a remnant of `dyn*` from the parser) - rust-lang#148675 (Remove eslint-js from npm dependencies) - rust-lang#148680 (Recover `[T: N]` as `[T; N]`) - rust-lang#148688 (Remove unused argument `features` from `eval_config_entry`) - rust-lang#148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 22 pull requests Successful merges: - rust-lang/rust#128666 (Add `overflow_checks` intrinsic) - rust-lang/rust#146305 (Add correct suggestion for multi-references for self type in method) - rust-lang/rust#147179 ([DebugInfo] Fix container types failing to find template args) - rust-lang/rust#147743 (Show packed field alignment in mir_transform_unaligned_packed_ref) - rust-lang/rust#148079 (Rename `downcast_[ref|mut]_unchecked` -> `downcast_unchecked_[ref|mut]`) - rust-lang/rust#148084 (Optimize path components iteration on platforms that don't have prefixes) - rust-lang/rust#148126 (Fix rust stdlib build failing for VxWorks) - rust-lang/rust#148204 (Modify contributor email entries in .mailmap) - rust-lang/rust#148279 (rustc_builtin_macros: rename bench parameter to avoid collisions with user-defined function names) - rust-lang/rust#148333 (constify result unwrap unchecked) - rust-lang/rust#148539 (Add Allocator proxy impls for Box, Rc, and Arc) - rust-lang/rust#148601 (`invalid_atomic_ordering`: also lint `update` & `try_update`) - rust-lang/rust#148612 (Add note for identifier with attempted hygiene violation) - rust-lang/rust#148613 (Switch hexagon targets to rust-lld) - rust-lang/rust#148619 (Enable std locking functions on AIX) - rust-lang/rust#148644 ([bootstrap] Make `--open` option work with `doc src/tools/error_index_generator`) - rust-lang/rust#148649 (don't completely reset `HeadUsages`) - rust-lang/rust#148673 (Remove a remnant of `dyn*` from the parser) - rust-lang/rust#148675 (Remove eslint-js from npm dependencies) - rust-lang/rust#148680 (Recover `[T: N]` as `[T; N]`) - rust-lang/rust#148688 (Remove unused argument `features` from `eval_config_entry`) - rust-lang/rust#148711 (Use the current lint note id when parsing `cfg!()`) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned jackh726 Oct 30, 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 30, 2025

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oli-obk reviewed Oct 30, 2025
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IntegralPilot requested a review from hkBst November 5, 2025 11:41

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hkBst approved these changes Nov 7, 2025
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rustc_builtin_macros: rename bench parameter to avoid collisions with…
67802e0
… user-defined function names

IntegralPilot force-pushed the master branch from fdf1ca4 to 67802e0Compare November 8, 2025 04:39

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 8, 2025

jhpratt mentioned this pull request Nov 8, 2025
Rollup of 16 pull requests #148686
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matthiaskrgr mentioned this pull request Nov 8, 2025
Rollup of 10 pull requests #148693
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matthiaskrgr mentioned this pull request Nov 8, 2025
Rollup of 9 pull requests #148701
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Zalathar mentioned this pull request Nov 9, 2025
Rollup of 22 pull requests #148721
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bors merged commit 645aa92 into rust-lang:masterNov 9, 2025
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rustbot added this to the 1.93.0 milestone Nov 9, 2025

github-actionsBot mentioned this pull request Nov 11, 2025
Toolchain upgrade to nightly-2026-02-09 flux-rs/flux#1345
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