clippy::unnecessary_debug_formatting: Checks for Debug formatting ({:?}) applied to an OsStr or Path. This includes: Format specifiers on format_args!() (width, precision have no effect) Format width too small for the format trait (e.g

let path = Path::new("...");
println!("The path is {:?}", path);

let path = Path::new("…");
println!("The path is {}", path.display());

[lints.clippy]
unnecessary_debug_formatting = "warn"

#![warn(clippy::unnecessary_debug_formatting)]

cargo clippy -- -W clippy::unnecessary-debug-formatting

Clippy's own documentation

What it does

Checks for Debug formatting ({:?}) applied to an OsStr or Path.

This includes:

• Format specifiers on format_args!() (width, precision have no effect)
• Format width too small for the format trait (e.g. {:#02x} outputs “0x1” so width 2 has no effect; minimum is 4 for alternate hex/octal/binary)

Why is this bad?

Rust doesn’t guarantee what Debug formatting looks like, and it could change in the future. OsStrs and Paths can be Display formatted using their display methods.

Furthermore, with Debug formatting, certain characters are escaped. Thus, a Debug formatted Path is less likely to be clickable.

Example

let path = Path::new("...");
println!("The path is {:?}", path);

Use instead:

let path = Path::new("…");
println!("The path is {}", path.display());

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

Related lints

• too_many_linesChecks for functions with a large amount of lines
• missing_errors_docChecks the doc comments of publicly visible functions that return a Result type and warns if there is no # Errors section
• must_use_candidateChecks for public functions that have no #[must_use] attribute, but return something not already marked must-use, have no mutable arg and mutate no statics
• unicode_not_nfcChecks for string literals that contain Unicode in a form that is not equal to its NFC-recomposition
• uninlined_format_argsDetect when a variable is not inlined in a format string, and suggests to inline it
• unnecessary_box_returnsboxed return of the sized type `std::string::String`
• unnecessary_joincalled `.collect::<Vec<String>>().join("")` on an iterator
• unnecessary_literal_boundDetects functions that are written to return &str that could return &'static str but instead return a &'a str
• unnecessary_semicolonChecks for the presence of a semicolon at the end of a match or if statement evaluating to ()

All 847 Clippy lints · Rust compiler errors · Cargo.toml checker