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// run-pass
// Tests that you can use an early-bound lifetime parameter as
// on of the generic parameters in a trait.
trait Trait<'a> {
fn long(&'a self) -> isize;
fn short<'b>(&'b self) -> isize;
}
fn poly_invoke<'c, T: Trait<'c>>(x: &'c T) -> (isize, isize) {
let l = x.long();
let s = x.short();
(l,s)
}
fn object_invoke1<'d>(x: &'d dyn Trait<'d>) -> (isize, isize) {
let l = x.long();
let s = x.short();
(l,s)
}
struct Struct1<'e> {
f: &'e (dyn Trait<'e>+'e)
}
fn field_invoke1<'f, 'g>(x: &'g Struct1<'f>) -> (isize,isize) {
let l = x.f.long();
let s = x.f.short();
(l,s)
}
struct Struct2<'h, 'i:'h> {
f: &'h (dyn Trait<'i>+'h)
}
fn object_invoke2<'j, 'k>(x: &'k dyn Trait<'j>) -> isize {
x.short()
}
fn field_invoke2<'l, 'm, 'n>(x: &'n Struct2<'l,'m>) -> isize {
x.f.short()
}
trait MakerTrait {
fn mk() -> Self;
}
fn make_val<T:MakerTrait>() -> T {
MakerTrait::mk()
}
trait RefMakerTrait<'q> {
fn mk(_: Self) -> &'q Self;
}
fn make_ref<'r, T:RefMakerTrait<'r>>(t:T) -> &'r T {
RefMakerTrait::mk(t)
}
impl<'s> Trait<'s> for (isize,isize) {
fn long(&'s self) -> isize {
let &(x,_) = self;
x
}
fn short<'b>(&'b self) -> isize {
let &(_,y) = self;
y
}
}
impl<'t> MakerTrait for Box<dyn Trait<'t>+'static> {
fn mk() -> Box<dyn Trait<'t>+'static> {
let tup: Box<(isize, isize)> = Box::new((4,5));
tup as Box<dyn Trait>
}
}
enum List<'l> {
Cons(isize, &'l List<'l>),
Null
}
impl<'l> List<'l> {
fn car<'m>(&'m self) -> isize {
match self {
&List::Cons(car, _) => car,
&List::Null => panic!(),
}
}
fn cdr<'n>(&'n self) -> &'l List<'l> {
match self {
&List::Cons(_, cdr) => cdr,
&List::Null => panic!(),
}
}
}
impl<'t> RefMakerTrait<'t> for List<'t> {
fn mk(l:List<'t>) -> &'t List<'t> {
l.cdr()
}
}
pub fn main() {
let t = (2,3);
let o = &t as &dyn Trait;
let s1 = Struct1 { f: o };
let s2 = Struct2 { f: o };
assert_eq!(poly_invoke(&t), (2,3));
assert_eq!(object_invoke1(&t), (2,3));
assert_eq!(field_invoke1(&s1), (2,3));
assert_eq!(object_invoke2(&t), 3);
assert_eq!(field_invoke2(&s2), 3);
let m : Box<dyn Trait> = make_val();
// assert_eq!(object_invoke1(&*m), (4,5));
// ~~~~~~~~~~~~~~~~~~~
// this call yields a compilation error; see ui/span/dropck-object-cycle.rs
// for details.
assert_eq!(object_invoke2(&*m), 5);
// The RefMakerTrait above is pretty strange (i.e., it is strange
// to consume a value of type T and return a &T). Easiest thing
// that came to my mind: consume a cell of a linked list and
// return a reference to the list it points to.
let l0 = List::Null;
let l1 = List::Cons(1, &l0);
let l2 = List::Cons(2, &l1);
let rl1 = &l1;
let r = make_ref(l2);
assert_eq!(rl1.car(), r.car());
}
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