Can't #[bench] a function named b #148275
Description
#![feature(test)]
extern crate test;
#[bench]
fn b(_: &mut test::bench::Bencher) {}I should be able to run this as a benchmark, but I got the following error:
error[E0308]: mismatched types
--> src/lib.rs:6:1
|
5 | #[bench]
| -------- in this attribute macro expansion
6 | fn b(_: &mut test::bench::Bencher) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expected `&mut Bencher`, found `TestDescAndFn`
| expected due to this
| constant defined here
| `b` is interpreted as a constant, not a new binding
| help: introduce a new binding instead: `other_b`
error[E0308]: mismatched types
--> src/lib.rs:6:1
|
5 | #[bench]
| -------- in this attribute macro expansion
6 | fn b(_: &mut test::bench::Bencher) {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| expected `&mut Bencher`, found `TestDescAndFn`
| arguments to this function are incorrect
|
note: function defined here
--> src/lib.rs:6:4
|
6 | fn b(_: &mut test::bench::Bencher) {}
| ^ ----------------------------
For more information about this error, try `rustc --explain E0308`.
It seems that the macro expansion of #[bench] has a name collision with a variable named b.
rust/compiler/rustc_builtin_macros/src/test.rs
Lines 210 to 218 in 292be5c
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Reproducible on the playground with version 1.93.0-nightly (2025-10-28 278a90913daf77077910) (click on the three dots on top left -> "test")
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