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// run-pass
// revisions: stock precise
#![feature(const_trait_impl)]
#![feature(const_mut_refs)]
#![feature(never_type)]
#![cfg_attr(precise, feature(const_precise_live_drops))]
use std::marker::Destruct;
struct S<'a>(&'a mut u8);
impl<'a> const Drop for S<'a> {
fn drop(&mut self) {
*self.0 += 1;
}
}
const fn a<T: ~const Destruct>(_: T) {}
const fn b() -> u8 {
let mut c = 0;
let _ = S(&mut c);
a(S(&mut c));
c
}
const C: u8 = b();
macro_rules! implements_const_drop {
($($exp:expr),*$(,)?) => {
$(
const _: () = a($exp);
)*
}
}
#[allow(dead_code)]
mod t {
pub struct Foo;
pub enum Bar { A }
pub fn foo() {}
pub struct ConstDrop;
impl const Drop for ConstDrop {
fn drop(&mut self) {}
}
pub struct HasConstDrop(pub ConstDrop);
pub struct TrivialFields(pub u8, pub i8, pub usize, pub isize);
#[const_trait]
pub trait SomeTrait {
fn foo();
}
impl const SomeTrait for () {
fn foo() {}
}
// non-const impl
impl SomeTrait for i32 {
fn foo() {}
}
pub struct ConstDropWithBound<T: ~const SomeTrait>(pub core::marker::PhantomData<T>);
impl<T: ~const SomeTrait> const Drop for ConstDropWithBound<T> {
fn drop(&mut self) {
T::foo();
}
}
pub struct ConstDropWithNonconstBound<T: SomeTrait>(pub core::marker::PhantomData<T>);
impl<T: SomeTrait> const Drop for ConstDropWithNonconstBound<T> {
fn drop(&mut self) {
// Note: we DON'T use the `T: SomeTrait` bound
}
}
}
use t::*;
implements_const_drop! {
1u8,
2,
3.0,
Foo,
Bar::A,
foo,
ConstDrop,
HasConstDrop(ConstDrop),
TrivialFields(1, 2, 3, 4),
&1,
&1 as *const i32,
ConstDropWithBound::<()>,
ConstDropWithNonconstBound::<i32>,
Result::<i32, !>::Ok(1),
}
fn main() {
struct HasDropGlue(#[allow(unused_tuple_struct_fields)] Box<u8>);
struct HasDropImpl;
impl Drop for HasDropImpl {
fn drop(&mut self) {
println!("not trivial drop");
}
}
// These types should pass because ~const in a non-const context should have no effect.
a(HasDropGlue(Box::new(0)));
a(HasDropImpl);
assert_eq!(C, 2);
}
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