Example of unsoundness in harfbuzz crate

harfbuzz-boom.rs

use harfbuzz::Blob;

fn create_blob() -> Blob {
    let vec = vec![1; 256];
    Blob::new_read_only(&vec)
    // BAD: vec is dropped here, the blob still holds a reference
}

fn blob_sum(blob: &Blob) -> u32 {
    blob.iter().map(|byte| *byte as u32).sum()
}

fn main() {
    let vec = vec![1; 256];
    let blob_ok = Blob::new_read_only(&vec);

    let blob_bad = create_blob();
    println!("sum of bytes should be {}", blob_sum(&blob_ok));
    println!("sum of bytes (bad) is {}", blob_sum(&blob_bad));
}