Clippy lint · Pedantic · checked with Clippy 0.1.99

clippy::ref_as_ptr: reference as raw pointer

What it meansChecks for casts of references to pointer using as and suggests std::ptr::from_ref and std::ptr::from_mut instead. It is in the pedantic group and off by default.

What you see

warning: reference as raw pointer
 --> main.rs:4:13
  |
4 | let a_ptr = a_ref as *const _;
  |             ^^^^^^^^^^^^^^^^^ help: try: `std::ptr::from_ref(a_ref)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#ref_as_ptr
  = note: `-W clippy::ref-as-ptr` implied by `-W clippy::pedantic`

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?

Using as casts may result in silently changing mutability or type.

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 a_ref = &1;
let a_ptr = a_ref as *const _;

Write this instead

let a_ref = &1;
let a_ptr = std::ptr::from_ref(a_ref);

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]
ref_as_ptr = "warn"

In code

#![warn(clippy::ref_as_ptr)]

One run

cargo clippy -- -W clippy::ref-as-ptr

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.

Pedanticgroup

allowdefault level

yesfixed by cargo clippy --fix

1.78.0added in Rust

Clippy's own documentation

What it does

Checks for casts of references to pointer using as and suggests std::ptr::from_ref and std::ptr::from_mut instead.

Why is this bad?

Using as casts may result in silently changing mutability or type.

Example

let a_ref = &1;
let a_ptr = a_ref as *const _;

Use instead:

let a_ref = &1;
let a_ptr = std::ptr::from_ref(a_ref);

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

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