Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
1 changed file
with
35 additions
and
0 deletions.
There are no files selected for viewing
35 changes: 35 additions & 0 deletions
35
src/test/ui/layout/issue-60431-unsized-tail-behind-projection.rs
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,35 @@ | ||
// rust-lang/rust#60431: This is a scenario where to determine the size of | ||
// `&Ref<Obstack>`, we need to know the concrete type of the last field in | ||
// `Ref<Obstack>` (i.e. its "struct tail"), and determining that concrete type | ||
// requires normalizing `Obstack::Dyn`. | ||
// | ||
// The old "struct tail" computation did not perform such normalization, and so | ||
// the compiler would ICE when trying to figure out if `Ref<Obstack>` is a | ||
// dynamically-sized type (DST). | ||
|
||
// run-pass | ||
|
||
use std::mem; | ||
|
||
pub trait Arena { | ||
type Dyn : ?Sized; | ||
} | ||
|
||
pub struct DynRef { | ||
_dummy: [()], | ||
} | ||
|
||
pub struct Ref<A: Arena> { | ||
_value: u8, | ||
_dyn_arena: A::Dyn, | ||
} | ||
|
||
pub struct Obstack; | ||
|
||
impl Arena for Obstack { | ||
type Dyn = DynRef; | ||
} | ||
|
||
fn main() { | ||
assert_eq!(mem::size_of::<&Ref<Obstack>>(), mem::size_of::<&[()]>()); | ||
} |