Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::manual_main_separator_str: taking a reference on `std::path::MAIN_SEPARATOR` conversion to `String`

What it meansChecks for references on std::path::MAIN_SEPARATOR.to_string() used to build a &str. It is in the complexity group and warns by default.

What you see

warning: taking a reference on `std::path::MAIN_SEPARATOR` conversion to `String`
 --> main.rs:3:15
  |
3 | let s: &str = &std::path::MAIN_SEPARATOR.to_string();
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `std::path::MAIN_SEPARATOR_STR`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_main_separator_str
  = note: `#[warn(clippy::manual_main_separator_str)]` on by default

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?

There exists a std::path::MAIN_SEPARATOR_STR which does not require an extra memory allocation.

Code that does something simple in a complicated way. 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

let s: &str = &std::path::MAIN_SEPARATOR.to_string();

Write this instead

let s: &str = std::path::MAIN_SEPARATOR_STR;

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::manual_main_separator_str)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
manual_main_separator_str = "allow"

One run

cargo clippy -- -A clippy::manual-main-separator-str

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.

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.70.0added in Rust

Clippy's own documentation

What it does

Checks for references on std::path::MAIN_SEPARATOR.to_string() used to build a &str.

Why is this bad?

There exists a std::path::MAIN_SEPARATOR_STR which does not require an extra memory allocation.

Example

let s: &str = &std::path::MAIN_SEPARATOR.to_string();

Use instead:

let s: &str = std::path::MAIN_SEPARATOR_STR;

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

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