RS.CLIPPY.FORMAT_IN_FORMAT_ARGS

`format!` used in a macro that does formatting

This checker is a Clippy lint created by The Rust Project Contributors. The documentation shown here is a copy of the original documentation for: format_in_format_args. Copyright ©2025 The Rust Team. All rights reserved.

What it does

Detects format! within the arguments of another macro that does formatting such as format! itself, write! or println!. Suggests inlining the format! call.

Why is this bad?

The recommended code is both shorter and avoids a temporary allocation.

Example

println!("error: {}", format!("something failed at {}", Location::caller()));

Use instead:

println!("error: something failed at {}", Location::caller());