Rust transmute/ownership drop test using free

droptest-free.rs

extern crate libc;

use std::mem;

struct Val {
    value: i32
}

impl Val {
    fn new(value: i32) -> Val {
        println!("Created {}", value);
        Val { value: value }
    }
}

impl Drop for Val {
    fn drop(&mut self) {
        println!("Destroyed {}", self.value);
    }
}

fn main() {
    let val = Box::new(Val::new(32));
    let ptr: *mut Val = unsafe { mem::transmute(val) };
    unsafe { libc::free(ptr as *mut libc::c_void); }
}

output

~/dev/projects/droptest $ cargo run
   Compiling droptest v0.1.0 (file:///Users/yupferris/dev/projects/droptest)
     Running `target/debug/droptest`
Created 32
droptest(726,0x7fff7ccb3300) malloc: *** error for object 0x10c825018: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
An unknown error occurred

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