Static rustc_lint_defs::builtin::UNALIGNED_REFERENCES

pub static UNALIGNED_REFERENCES: &Lint

The unaligned_references lint detects unaligned references to fields of packed structs.

Example

#[repr(packed)]
pub struct Foo {
    field1: u64,
    field2: u8,
}

fn main() {
    unsafe {
        let foo = Foo { field1: 0, field2: 0 };
        let _ = &foo.field1;
        println!("{}", foo.field1); // An implicit `&` is added here, triggering the lint.
    }
}

{{produces}}

Explanation

Creating a reference to an insufficiently aligned packed field is undefined behavior and should be disallowed. Using an unsafe block does not change anything about this. Instead, the code should do a copy of the data in the packed field or use raw pointers and unaligned accesses. See issue #82523 for more information.