60 lines
1.3 KiB
Rust
60 lines
1.3 KiB
Rust
#![feature(ptr_internals)]
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fn main() {
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into_raw();
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into_unique();
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boxed_pair_to_vec();
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}
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fn into_raw() {
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unsafe {
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let b = Box::new(4i32);
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let r = Box::into_raw(b);
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// "lose the tag"
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let r2 = ((r as usize) + 0) as *mut i32;
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*(&mut *r2) = 7;
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// Use original ptr again
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*(&mut *r) = 17;
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drop(Box::from_raw(r));
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}
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}
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fn into_unique() {
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unsafe {
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let b = Box::new(4i32);
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let u = Box::into_unique(b).0;
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// "lose the tag"
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let r = ((u.as_ptr() as usize) + 0) as *mut i32;
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*(&mut *r) = 7;
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// Use original ptr again.
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drop(Box::from_raw(u.as_ptr()));
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}
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}
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fn boxed_pair_to_vec() {
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#[repr(C)]
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#[derive(Debug)]
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struct PairFoo {
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fst: Foo,
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snd: Foo,
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}
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#[derive(Debug)]
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struct Foo(u64);
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fn reinterstruct(box_pair: Box<PairFoo>) -> Vec<Foo> {
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let ref_pair = Box::leak(box_pair) as *mut PairFoo;
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let ptr_foo = unsafe { std::ptr::addr_of_mut!((*ref_pair).fst) };
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unsafe { Vec::from_raw_parts(ptr_foo, 2, 2) }
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}
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let pair_foo = Box::new(PairFoo { fst: Foo(42), snd: Foo(1337) });
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println!("pair_foo = {:?}", pair_foo);
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for (n, foo) in reinterstruct(pair_foo).into_iter().enumerate() {
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println!("foo #{} = {:?}", n, foo);
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}
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}
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