Clippy lint · Suspicious · checked with Clippy 0.1.99

clippy::cast_slice_from_raw_parts: Checks for a raw slice being cast to a slice pointer

What it meansChecks for a raw slice being cast to a slice pointer It is in the suspicious group and warns by default.

Does it matter?

This can result in multiple &mut references to the same location when only a pointer is required. ptr::slice_from_raw_parts is a safe alternative that doesn’t require the same safety requirements to be upheld.

Code that is most likely wrong or useless. 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 _: *const [u8] = std::slice::from_raw_parts(ptr, len) as *const _;
let _: *mut [u8] = std::slice::from_raw_parts_mut(ptr, len) as *mut _;

Write this instead

let _: *const [u8] = std::ptr::slice_from_raw_parts(ptr, len);
let _: *mut [u8] = std::ptr::slice_from_raw_parts_mut(ptr, len);

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_slice_from_raw_parts)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
cast_slice_from_raw_parts = "allow"

One run

cargo clippy -- -A clippy::cast-slice-from-raw-parts

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.

Suspiciousgroup

warndefault level

yesfixed by cargo clippy --fix

1.65.0added in Rust

Clippy's own documentation

What it does

Checks for a raw slice being cast to a slice pointer

Why is this bad?

This can result in multiple &mut references to the same location when only a pointer is required. ptr::slice_from_raw_parts is a safe alternative that doesn’t require the same safety requirements to be upheld.

Example

let _: *const [u8] = std::slice::from_raw_parts(ptr, len) as *const _;
let _: *mut [u8] = std::slice::from_raw_parts_mut(ptr, len) as *mut _;

Use instead:

let _: *const [u8] = std::ptr::slice_from_raw_parts(ptr, len);
let _: *mut [u8] = std::ptr::slice_from_raw_parts_mut(ptr, len);

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

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