Static NON_FMT_PANICS

static NON_FMT_PANICS: &Lint

The non_fmt_panics lint detects panic!(..) invocations where the first argument is not a formatting string.

Example

panic!("{}");
panic!(123);

{{produces}}

Explanation

In Rust 2018 and earlier, panic!(x) directly uses x as the message. That means that panic!("{}") panics with the message "{}" instead of using it as a formatting string, and panic!(123) will panic with an i32 as message.

Rust 2021 always interprets the first argument as format string.