literal_string_with_formatting_args false positive on test

[tamird]

Summary

See reproducer below. I can't reproduce this in playground because it doesn't run clippy with --all-targets.

Lint Name

literal_string_with_formatting_args

Reproducer

I tried this code:

pub fn parse(_: &str) -> Result<Vec<String>, String> {
    unimplemented!()
}

#[test]
fn test_parse() {
    assert!(parse(
        #[allow(clippy::literal_string_with_formatting_args)]
        "foo {:}"
    )
    .is_err());
}

I saw this happen:

$ cargo +nightly clippy --all-targets
warning: this looks like a formatting argument but it is not part of a formatting macro
 --> src/lib.rs:5:6
  |
5 |     #[test]
  |      ^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#literal_string_with_formatting_args
  = note: `#[warn(clippy::literal_string_with_formatting_args)]` on by default

I expected to see this happen:
No warnings.

Version

rustc 1.85.0-nightly (917bfa784 2024-12-26)
binary: rustc
commit-hash: 917bfa78478cbcc77406e5ea37b24c3eedefacf4
commit-date: 2024-12-26
host: aarch64-apple-darwin
release: 1.85.0-nightly
LLVM version: 19.1.6

Additional Labels

No response

[DaniPopes]

Also just encountered this inside of assert!(). Similar/smaller:

pub fn bad() {
    let value = 0;
    assert!(format!("{value}").is_ascii());
}

warning: this looks like a formatting argument but it is not part of a formatting macro
 --> src/lib.rs:2:14
  |
2 |       let value = 0;
  |  ______________^
3 | |     assert!(format!("{value}").is_ascii());
  | |_^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#literal_string_with_formatting_args
  = note: `#[warn(clippy::literal_string_with_formatting_args)]` on by default

playground

It looks like it tries to report the lint on a dummy span + some offset since in my original error it gets reported in lib.rs in some random comment at the top of the file.

[amircodota]

Got a few more examples

This is an actix-web route

#[route(
    "/forward/{path:.*}",
    method = "GET",
    method = "POST",
    method = "PUT",
    method = "OPTION"
)]
async fn forward(
    request: HttpRequest,
    body: Payload,
    data: Data<HttpState>,
    path: web::Path<String>,
) -> impl Responder {

This is error_chain bail macro

bail!("failed to prepare resumable config object: {e}")

In docs comment

/// Since there's no `lib.rs` or `main.rs` file here in the `tests` directory -

Also appears on some imports with the with word

use crate::common::server_utils::assert_notification_message_with_text;

[profetia]

Might be a FN on from_expansion

[profetia]

@rustbot claim

[samueltardieu]

Ping @GuillaumeGomez

[ilammy]

More examples of false positives.

Clippy doesn't like .clippy.toml!

warning: this looks like a formatting argument but it is not part of a formatting macro
 --> [redacted]/.clippy.toml:2:27
  |
2 | too-many-arguments-threshold = 9
  |                           ^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#literal_string_with_formatting_args
  = note: `#[warn(clippy::literal_string_with_formatting_args)]` on by default

I don't know whether it's the attribute or the import that's triggering it:

warning: these look like formatting arguments but are not part of a formatting macro
 --> [redacted]/src/main.rs:1:22
  |
1 | #![allow(clippy::too_long_first_doc_paragraph)]
  |                      ^^^^^^^^
...
9 |         thread::{fresh_run, join_cluster, start_cluster},
  |               ^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#literal_string_with_formatting_args
  = note: `#[warn(clippy::literal_string_with_formatting_args)]` on by default

[profetia]

Just find another way to trigger the FP

// file name: {value}.rs
#![crate_name = "strange_file_name"]
#![allow(unused)]

fn another_bad() {
    let value = 0;
    dbg!("something");
}

fn main() {}

[GuillaumeGomez]

Wow nice. Gonna take a look in the next days.

[GuillaumeGomez]

@profetia: I can't trigger the lint with your code.