Clippy lints / Pedantic
Clippy lint · Pedantic · checked with Clippy 0.1.99
clippy::needless_raw_string_hashes: unnecessary hashes around raw string literal
What it meansChecks for raw string literals with an unnecessary amount of hashes around them. It is in the pedantic group and off by default.
What you see
warning: unnecessary hashes around 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_string_hashes = note: `-W clippy::needless-raw-string-hashes` implied by `-W clippy::pedantic` help: remove 2 hashes from both sides of the string literal | 3 - let r = r###"Hello, "world"!"###; 3 + let r = 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?
It’s just unnecessary, and makes it look like there’s more escaping needed than is actually necessary.
Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.
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 = 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_string_hashes = "warn"In code
#![warn(clippy::needless_raw_string_hashes)]One run
cargo clippy -- -W clippy::needless-raw-string-hashesThe [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.
Settings in clippy.toml
allow-one-hash-in-raw-strings: Whether to allow r#""# when r"" can be used
Clippy's own documentation
What it does
Checks for raw string literals with an unnecessary amount of hashes around them.
Why is this bad?
It’s just unnecessary, and makes it look like there’s more escaping needed than is actually necessary.
Example
let r = r###"Hello, "world"!"###;
Use instead:
let r = r#"Hello, "world"!"#;
Configuration
-
allow-one-hash-in-raw-strings: Whether to allowr#""#whenr""can be used(default:
false)
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
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- needless_continueThe lint checks for if-statements appearing in loops that contain a continue statement in either their main blocks or their else-blocks, when omitting the else-block possibly with some rearrangement of code can make the code easier to understand. The lint also checks if the last statement in the loop is a continue
- needless_for_eachneedless use of `for_each`
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- no_effect_underscore_bindingbinding to `_` prefixed variable with no side-effect
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- non_std_lazy_staticsLints when once_cell::sync::Lazy or lazy_static! are used to define a static variable, and suggests replacing such cases with std::sync::LazyLock instead. Note: This lint will not trigger in crate with no_std context, or with MSRV < 1.80.0
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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