Clippy lint · Restriction · checked with Clippy 0.1.99

clippy::needless_raw_strings: unnecessary raw string literal

What it meansChecks for raw string literals where a string literal can be used instead. It is in the restriction group and off by default.

What you see

warning: unnecessary raw string literal
 --> main.rs:3:9
  |
3 | let r = r"Hello, world!";
  |         ^^^^^^^^^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#needless_raw_strings
  = note: requested on the command line with `-W clippy::needless-raw-strings`
help: use a plain string literal instead
  |
3 - let r = r"Hello, world!";
3 + let r = "Hello, world!";
  |

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

For consistent style by using simpler string literals whenever possible. However, there are many cases where using a raw string literal is more idiomatic than a string literal, so it’s opt-in.

Lints that forbid language features for specific codebases (no unwrap, no indexing...). Off by default; pick them one by one, never the whole group.

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

let r = r"Hello, world!";

Write this instead

let r = "Hello, world!";

Turn it off, or on

It is off by default. To use it, set it to warn or deny:

Whole crate (Cargo.toml)

[lints.clippy]
needless_raw_strings = "warn"

In code

#![warn(clippy::needless_raw_strings)]

One run

cargo clippy -- -W clippy::needless-raw-strings

The [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.

Restrictiongroup

allowdefault level

yesfixed by cargo clippy --fix

1.72.0added in Rust

Clippy's own documentation

What it does

Checks for raw string literals where a string literal can be used instead.

Why restrict this?

For consistent style by using simpler string literals whenever possible.

However, there are many cases where using a raw string literal is more idiomatic than a string literal, so it’s opt-in.

Example

let r = r"Hello, world!";

Use instead:

let r = "Hello, world!";

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

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