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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/regions/regions-early-bound-trait-param.rs | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/src/test/ui/regions/regions-early-bound-trait-param.rs b/src/test/ui/regions/regions-early-bound-trait-param.rs new file mode 100644 index 000000000..a28bd14ba --- /dev/null +++ b/src/test/ui/regions/regions-early-bound-trait-param.rs @@ -0,0 +1,132 @@ +// 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()); +} |