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72 lines
2.1 KiB
Rust
72 lines
2.1 KiB
Rust
// run-pass
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// Iota-reduction is a rule in the Calculus of (Co-)Inductive Constructions,
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// which "says that a destructor applied to an object built from a constructor
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// behaves as expected". -- https://coq.inria.fr/doc/language/core/conversion.html#iota-reduction
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//
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// It's a little more complicated here, because of pointers and regions and
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// trying to get assert failure messages that at least identify which case
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// failed.
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enum E<T> { Thing(isize, T), #[allow(unused_tuple_struct_fields)] Nothing((), ((), ()), [i8; 0]) }
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impl<T> E<T> {
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fn is_none(&self) -> bool {
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match *self {
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E::Thing(..) => false,
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E::Nothing(..) => true
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}
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}
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fn get_ref(&self) -> (isize, &T) {
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match *self {
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E::Nothing(..) => panic!("E::get_ref(Nothing::<{}>)", stringify!(T)),
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E::Thing(x, ref y) => (x, y)
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}
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}
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}
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macro_rules! check_option {
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($e:expr, $T:ty) => {{
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check_option!($e, $T, |ptr| assert_eq!(*ptr, $e));
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}};
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($e:expr, $T:ty, |$v:ident| $chk:expr) => {{
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assert!(None::<$T>.is_none());
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let e = $e;
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let s_ = Some::<$T>(e);
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let $v = s_.as_ref().unwrap();
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$chk
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}}
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}
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macro_rules! check_fancy {
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($e:expr, $T:ty) => {{
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check_fancy!($e, $T, |ptr| assert_eq!(*ptr, $e));
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}};
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($e:expr, $T:ty, |$v:ident| $chk:expr) => {{
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assert!(E::Nothing::<$T>((), ((), ()), [23; 0]).is_none());
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let e = $e;
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let t_ = E::Thing::<$T>(23, e);
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match t_.get_ref() {
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(23, $v) => { $chk }
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_ => panic!("Thing::<{}>(23, {}).get_ref() != (23, _)",
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stringify!($T), stringify!($e))
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}
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}}
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}
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macro_rules! check_type {
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($($a:tt)*) => {{
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check_option!($($a)*);
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check_fancy!($($a)*);
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}}
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}
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pub fn main() {
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check_type!(&17, &isize);
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check_type!(Box::new(18), Box<isize>);
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check_type!("foo".to_string(), String);
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check_type!(vec![20, 22], Vec<isize>);
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check_type!(main, fn(), |pthing| {
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assert_eq!(main as fn(), *pthing as fn())
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});
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}
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