Clippy lints / Suspicious
Clippy lint · Suspicious · checked with Clippy 0.1.99
clippy::cast_nan_to_int: casting a known NaN to u64
What it meansChecks for a known NaN float being cast to an integer It is in the suspicious group and warns by default.
What you see
warning: casting a known NaN to u64 --> main.rs:3:9 | 3 | let _ = (0.0_f32 / 0.0) as u64; | ^^^^^^^^^^^^^^^^^^^^^^ | = note: this always evaluates to 0 = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#cast_nan_to_int = note: `#[warn(clippy::cast_nan_to_int)]` 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?
NaNs are cast into zero, so one could simply use this and make the code more readable. The lint could also hint at a programmer error.
Code that is most likely wrong or useless. Warns by default.
How to fix it
Clippy does not fix this one automatically. Change the code by hand:
Flagged
let _ = (0.0_f32 / 0.0) as u64;
Write this instead
let _ = 0_u64;
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::cast_nan_to_int)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
cast_nan_to_int = "allow"One run
cargo clippy -- -A clippy::cast-nan-to-intThe [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 a known NaN float being cast to an integer
Why is this bad?
NaNs are cast into zero, so one could simply use this and make the code more readable. The lint could also hint at a programmer error.
Example
let _ = (0.0_f32 / 0.0) as u64;
Use instead:
let _ = 0_u64;
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- cast_abs_to_unsignedcasting the result of `i32::abs()` to u32
- cast_enum_constructorcast of an enum tuple constructor to an integer
- cast_enum_truncationcasting `main::E::X` to `u8` will truncate the value
- cast_slice_from_raw_partsChecks for a raw slice being cast to a slice pointer
- confusing_method_to_numeric_castcasting function pointer `u16::max` to `usize`
- const_is_emptythis expression always evaluates to true
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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