Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::print_with_newline: This lint warns when you use print!() with a format string that ends in a newline
What it meansThis lint warns when you use print!() with a format string that ends in a newline. It is in the style group and warns by default.
Does it matter?
You should use println!() instead, which appends the newline.
Code that works but is not idiomatic Rust. Warns by default.
How to fix it
Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.
Flagged
print!("Hello {}!\n", name);
Write this instead
println!("Hello {}!", name);
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::print_with_newline)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
print_with_newline = "allow"One run
cargo clippy -- -A clippy::print-with-newlineThe [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.
Clippy's own documentation
What it does
This lint warns when you use print!() with a format
string that ends in a newline.
Why is this bad?
You should use println!() instead, which appends the
newline.
Example
print!("Hello {}!\n", name);
use println!() instead
println!("Hello {}!", name);
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- needless_returnunneeded `return` statement
- new_without_defaultChecks for public types with a pub fn new() -> Self method and no implementation of Default
- len_zeroChecks for getting the length of something via .len() just to compare to zero, and suggests using .is_empty() where applicable
- owned_cowneedlessly owned Cow type
- partialeq_to_nonebinary comparison to literal `Option::None`
- print_literalliteral with an empty format string
- println_empty_stringempty string literal in `println!`
- ptr_argThis lint checks for function arguments of type &String, &Vec, &PathBuf, and Cow<_>
- ptr_equse `std::ptr::eq` when comparing raw pointers
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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