Regressions in 1.93.0 crater run: rustdoc errors on invalid `#[test]` attribute

[theemathas]

This issue tracks the regressions found in the 1.93.0 beta crater run which involve rustdoc producing an error due to a #[test] attribute being applied to the wrong thing.

The regressions are categorized based on what the #[test] attribute is applied to.

#[test] on an associated function

Error output

[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]   --> src/plot.rs:60:5
[INFO] [stdout]    |
[INFO] [stdout] 60 |     #[test]
[INFO] [stdout]    |     ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout]    |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]    |
[INFO] [stdout] 60 -     #[test]
[INFO] [stdout] 60 +     #[cfg(test)]
[INFO] [stdout]    |

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/Nixes.rust_plot/log.txt

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/abomb4.rust-five/log.txt

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/laikas123.rusql/log.txt

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/reg/graphify-0.1.0/log.txt

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/reg/namespace-0.1.0/log.txt

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/pgberlureau.kernel_shell/log.txt

#[test] on a use statement

Error output

[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]   --> src/task5.rs:1:1
[INFO] [stdout]    |
[INFO] [stdout]  1 | #[test]
[INFO] [stdout]    | ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout] ...
[INFO] [stdout] 24 | use std::collections::HashMap;
[INFO] [stdout]    | ------------------------------ expected a non-associated function, found a `use` import
[INFO] [stdout]    |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]    |
[INFO] [stdout]  1 - #[test]
[INFO] [stdout]  1 + #[cfg(test)]
[INFO] [stdout]    |

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/OrlovBohdan._11_Collection_Types_11_3_HashMap/log.txt

#[test] on a macro invocation (which is a warning, but then this results in a seemingly unrelated error?)

Error output

[INFO] [stdout] warning: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]    --> src/backend/geometry.rs:490:1
[INFO] [stdout]     |
[INFO] [stdout] 490 |   #[test]
[INFO] [stdout]     |   ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout] 491 | / quickcheck! {
[INFO] [stdout] 492 | |     fn check_intersect_two_circles(
[INFO] [stdout] 493 | |         x1: f64,
[INFO] [stdout] 494 | |         y1: f64,
[INFO] [stdout] ...   |
[INFO] [stdout] 586 | | }
[INFO] [stdout]     | |_- expected a non-associated function, found an item macro invocation
[INFO] [stdout]     |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]     |
[INFO] [stdout] 490 - #[test]
[INFO] [stdout] 490 + #[cfg(test)]
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: cannot find macro `quickcheck` in this scope
[INFO] [stdout]    --> src/backend/geometry.rs:491:1
[INFO] [stdout]     |
[INFO] [stdout] 491 | quickcheck! {
[INFO] [stdout]     | ^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `quickcheck` is in scope, but it is a crate, not a macro

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/loovjo.drawmetry/log.txt

#[test] on an impl block

Error output

[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]    --> src/shell/fs.rs:309:1
[INFO] [stdout]     |
[INFO] [stdout] 309 |   #[test] // TODO : remove it
[INFO] [stdout]     |   ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout] 310 | / impl std::fmt::Display for Fdesc {
[INFO] [stdout] 311 | |     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> core::fmt::Result {
[INFO] [stdout] 312 | |         let name: std::string::String = self.name.iter().collect();
[INFO] [stdout] 313 | |         write!(f, "
[INFO] [stdout] ...   |
[INFO] [stdout] 320 | | }
[INFO] [stdout]     | |_- expected a non-associated function, found an implementation
[INFO] [stdout]     |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]     |
[INFO] [stdout] 309 - #[test] // TODO : remove it
[INFO] [stdout] 309 + #[cfg(test)] // TODO : remove it
[INFO] [stdout]     |

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/gh/pgberlureau.kernel_shell/log.txt

#[test] on a mod declaration

Error output

[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]    --> src/common/git.rs:152:1
[INFO] [stdout]     |
[INFO] [stdout] 152 |   #[test]
[INFO] [stdout]     |   ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout] 153 | / mod tests {
[INFO] [stdout] 154 | |     use super::*;
[INFO] [stdout] 155 | |     use std::str::FromStr;
[INFO] [stdout] ...   |
[INFO] [stdout] 210 | | }
[INFO] [stdout]     | |_- expected a non-associated function, found a module
[INFO] [stdout]     |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]     |
[INFO] [stdout] 152 - #[test]
[INFO] [stdout] 152 + #[cfg(test)]
[INFO] [stdout]     |

https://crater-reports.s3.amazonaws.com/beta-rustdoc-1.93-3/beta-2025-12-22/reg/openfare-0.6.2/log.txt

#[test] on a statement in a doctest

Error output

[INFO] [stdout] ---- src/check.rs - check::check (line 8) stdout ----
[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]  --> src/check.rs:12:1
[INFO] [stdout]   |
[INFO] [stdout] 7 | #[test]
[INFO] [stdout]   | ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout]   |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]   |
[INFO] [stdout] 7 - #[test]
[INFO] [stdout] 7 + #[cfg(test)]
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]   --> src/check.rs:15:1
[INFO] [stdout]    |
[INFO] [stdout] 10 | #[test]
[INFO] [stdout]    | ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout]    |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]    |
[INFO] [stdout] 10 - #[test]
[INFO] [stdout] 10 + #[cfg(test)]
[INFO] [stdout]    |

https://crater-reports.s3.amazonaws.com/beta-1.93-4/beta-2025-12-22/reg/antelope-0.2.0/log.txt

#[test] on a macro invocation in a doctest

Error output

[INFO] [stdout] ---- src/../README.md - (line 82) stdout ----
[INFO] [stdout] error: the `#[test]` attribute may only be used on a free function
[INFO] [stdout]   --> src/../README.md:95:1
[INFO] [stdout]    |
[INFO] [stdout] 16 | #[test]
[INFO] [stdout]    | ^^^^^^^ the `#[test]` macro causes a function to be run as a test and has no effect on non-functions
[INFO] [stdout]    |
[INFO] [stdout] help: replace with conditional compilation to make the item only exist when tests are being run
[INFO] [stdout]    |
[INFO] [stdout] 16 - #[test]
[INFO] [stdout] 16 + #[cfg(test)]
[INFO] [stdout]    |

https://crater-reports.s3.amazonaws.com/beta-1.93-4/beta-2025-12-22/reg/should_error-0.1.1/log.txt

[theemathas]

I did a bisection with the following source code:

pub struct Thing;

impl Thing {
    #[test]
    pub fn foo() {}
}

Result:

searched toolchains f435972085b697a1ece8ee6a1ac76efff8d1df7b through 66428d92bec337ed4785d695d0127276a482278c


********************************************************************************
Regression in b1b08cdef5ed3bca71c0d6638fccadc90d2e0ea3
********************************************************************************

Attempting to search unrolled perf builds
adding local env GITHUB_TOKEN value to headers in github query
adding local env GITHUB_TOKEN value to headers in github query
Found commits ["9b9e0731", "4da4cc50", "44a90839", "112f3549", "d464bf7d", "df1ef36b", "d5174458", "ce97567b", "1a8f030b", "52b80877", "c475ad57", "30e5a3e5"]
installing 9b9e0731889cba19bb3a7f778c12e6772cb6721a
uninstalling 9b9e0731889cba19bb3a7f778c12e6772cb6721a
installing 4da4cc50d15322746cc27267d8ceab7810c033d1
uninstalling 4da4cc50d15322746cc27267d8ceab7810c033d1
installing 44a908398ca928140cf25894f05190bc34978f7a
uninstalling 44a908398ca928140cf25894f05190bc34978f7a
installing 112f354918b0bdb6ad953b2b4a4092c6131a14ba
uninstalling 112f354918b0bdb6ad953b2b4a4092c6131a14ba
installing d464bf7d75aa5f21235dace21b2f161590d333a5
uninstalling d464bf7d75aa5f21235dace21b2f161590d333a5
installing df1ef36b1a48e35bc701358d5f2a314bb8c54236
uninstalling df1ef36b1a48e35bc701358d5f2a314bb8c54236
installing d517445835ba82a6c917dcf159135409110a205d
uninstalling d517445835ba82a6c917dcf159135409110a205d
installing ce97567b1394860a895a1d0e85446d9e85847939
uninstalling ce97567b1394860a895a1d0e85446d9e85847939
installing 1a8f030b823512f4bd89de859cc38a5178842b51
uninstalling 1a8f030b823512f4bd89de859cc38a5178842b51
installing 52b8087768d5f3b5bcb6c9102cc6e27a9029f3c6
uninstalling 52b8087768d5f3b5bcb6c9102cc6e27a9029f3c6
installing c475ad57cf8442c3544d36b55d4647a06940efb6
uninstalling c475ad57cf8442c3544d36b55d4647a06940efb6
installing 30e5a3e54bbc0673d27c5e9e24a9c88e8bbb9207
uninstalling 30e5a3e54bbc0673d27c5e9e24a9c88e8bbb9207
ERROR: none of the toolchains satisfied the predicate

Presumably regressed in #147841.

cc @jdonszelmann, @WaffleLapkin