Clippy lint · Pedantic · checked with Clippy 0.1.99

clippy::unsafe_derive_deserialize: Checks for deriving serde::Deserialize on a type that has methods using unsafe

What it meansChecks for deriving serde::Deserialize on a type that has methods using unsafe. It is in the pedantic group and off by default.

Does it matter?

Deriving serde::Deserialize will create a constructor that may violate invariants held by another constructor.

Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.

How to fix it

Clippy does not fix this one automatically. Change the code by hand:

Flagged

use serde::Deserialize;

#[derive(Deserialize)]
pub struct Foo {
    // ..
}

impl Foo {
    pub fn new() -> Self {
        // setup here ..
    }

    pub unsafe fn parts() -> (&str, &str) {
        // assumes invariants hold
    }
}

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]
unsafe_derive_deserialize = "warn"

In code

#![warn(clippy::unsafe_derive_deserialize)]

One run

cargo clippy -- -W clippy::unsafe-derive-deserialize

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

nofixed by cargo clippy --fix

1.45.0added in Rust

Clippy's own documentation

What it does

Checks for deriving serde::Deserialize on a type that has methods using unsafe.

Why is this bad?

Deriving serde::Deserialize will create a constructor that may violate invariants held by another constructor.

Example

use serde::Deserialize;

#[derive(Deserialize)]
pub struct Foo {
    // ..
}

impl Foo {
    pub fn new() -> Self {
        // setup here ..
    }

    pub unsafe fn parts() -> (&str, &str) {
        // assumes invariants hold
    }
}

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

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