Odd Lifetime error when compiling async fn with two non-static and one static reference

[lily-mara]

I tried this code:

struct Foo;

async fn foo(x: &Foo, y: &Foo, z: &'static Foo) {}

I expected to see this happen: The function should compile and be a no-op

Instead, this happened: The code fails to compile with the following error message

error[E0700]: hidden type for `impl Trait` captures lifetime that does not appear in bounds
 --> src/lib.rs:3:49
  |
3 | async fn foo(x: &Foo, y: &Foo, z: &'static Foo) {}
  |                                                 ^
  |

Meta

rustc --version --verbose:

1.46.0

I have reproduced this issue with 1.46.0 as well as nightly 1.48.0 2020-09-08, both in the Rust playground.

Solutions I tried:

Code	Summary	Result
async fn foo<'a>(x: &'a Foo, y: &'a Foo, z: &'static Foo) {}	Constraining x and y to the same lifetime	COMPILES
async fn foo(x: &Foo, y: &Foo, z: &Foo) {}	removing the static lifetime on z	COMPILES
async fn foo(x: &Foo, z: &'static Foo) {}	removing x, y, or z	COMPILES
async fn foo<'x, 'y>(x: &'x Foo, y: &'y Foo, z: &'static Foo) {}	Constraining x and y to independent lifetimes	FAILS TO COMPILE
async fn foo<'x, 'y: 'x>(x: &'x Foo, y: &'y Foo, z: &'static Foo) {}	Constraining x and y to lifetimes that are not independent	COMPILES

[SNCPlay42]

I think this is a duplicate/another case of #63033.

[jonas-schievink]

Indeed, closing as a duplicate