1 // rust-lang/rust#60431: This is a scenario where to determine the size of
2 // `&Ref<Obstack>`, we need to know the concrete type of the last field in
3 // `Ref<Obstack>` (i.e. its "struct tail"), and determining that concrete type
4 // requires normalizing `Obstack::Dyn`.
5 //
6 // The old "struct tail" computation did not perform such normalization, and so
7 // the compiler would ICE when trying to figure out if `Ref<Obstack>` is a
8 // dynamically-sized type (DST).
9 
10 // run-pass
11 
12 use std::mem;
13 
14 pub trait Arena {
15     type Dyn : ?Sized;
16 }
17 
18 pub struct DynRef {
19     _dummy: [()],
20 }
21 
22 pub struct Ref<A: Arena> {
23     _value: u8,
24     _dyn_arena: A::Dyn,
25 }
26 
27 pub struct Obstack;
28 
29 impl Arena for Obstack {
30     type Dyn = DynRef;
31 }
32 
main()33 fn main() {
34     assert_eq!(mem::size_of::<&Ref<Obstack>>(), mem::size_of::<&[()]>());
35 }
36