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small fix to the tutorial-ffi destructor example #6244

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Merged
bors merged 1 commit into from
May 5, 2013
Merged

small fix to the tutorial-ffi destructor example #6244

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11 changes: 4 additions & 7 deletions doc/tutorial-ffi.md
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Original file line number Diff line number Diff line change
Expand Up @@ -150,11 +150,7 @@ wrapping `malloc` and `free`:

~~~~
use core::libc::{c_void, size_t, malloc, free};

#[abi = "rust-intrinsic"]
extern "rust-intrinsic" mod rusti {
fn init<T>() -> T;
}
use core::unstable::intrinsics;

// a wrapper around the handle returned by the foreign code
pub struct Unique<T> {
Expand All @@ -166,7 +162,8 @@ pub impl<'self, T: Owned> Unique<T> {
unsafe {
let ptr = malloc(core::sys::size_of::<T>() as size_t) as *mut T;
assert!(!ptr::is_null(ptr));
*ptr = value;
// `*ptr` is uninitialized, and `*ptr = value` would attempt to destroy it
intrinsics::move_val_init(&mut *ptr, value);
Unique{ptr: ptr}
}
}
Expand All @@ -186,7 +183,7 @@ pub impl<'self, T: Owned> Unique<T> {
impl<T: Owned> Drop for Unique<T> {
fn finalize(&self) {
unsafe {
let mut x = rusti::init(); // dummy value to swap in
let mut x = intrinsics::init(); // dummy value to swap in
x <-> *self.ptr; // moving the object out is needed to call the destructor
free(self.ptr as *c_void)
}
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