Clippy lints / Complexity
Clippy lint · Complexity · checked with Clippy 0.1.99
clippy::char_lit_as_u8: Checks for expressions where a character literal is cast to u8 and suggests using a byte literal instead
What it meansChecks for expressions where a character literal is cast to u8 and suggests using a byte literal instead. It is in the complexity group and warns by default.
Does it matter?
In general, casting values to smaller types is error-prone and should be avoided where possible. In the particular case of converting a character literal to u8, it is easy to avoid by just using a byte literal instead. As an added bonus, b'a' is also slightly shorter than 'a' as u8.
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
'x' as u8
Write this instead
b'x'
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::char_lit_as_u8)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
char_lit_as_u8 = "allow"One run
cargo clippy -- -A clippy::char-lit-as-u8The [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
Checks for expressions where a character literal is cast
to u8 and suggests using a byte literal instead.
Why is this bad?
In general, casting values to smaller types is
error-prone and should be avoided where possible. In the particular case of
converting a character literal to u8, it is easy to avoid by just using a
byte literal instead. As an added bonus, b'a' is also slightly shorter
than 'a' as u8.
Example
'x' as u8
A better version, using the byte literal:
b'x'
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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- clone_on_copyusing `clone` on type `u64` which implements the `Copy` trait
- type_complexityChecks for types used in structs, parameters and let declarations above a certain complexity threshold
- borrow_deref_refderef on an immutable reference
- borrowed_boxChecks for usage of &Box<T> anywhere in the code. Check the Box documentation for more information
- bytes_count_to_lenusing long and hard to read `.bytes().count()`
- default_constructed_unit_structsChecks for construction on unit struct using default
- deprecated_cfg_attr`cfg_attr` is deprecated for rustfmt and got replaced by tool attributes
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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