False E0644 closure/generator type that references itself; new in nightly-2022-11-05

[kpreid]

I tried this code with cargo +nightly-2022-11-05 check:

pub trait Fn0: Fn() -> Self::Out {
    type Out;
}

impl<F: Fn() -> ()> Fn0 for F {
    type Out = ();
}

pub fn closure_typer(_: impl Fn0) {}

fn main() {
    closure_typer(move || {});
}

I expected to see this happen: successful compilation

Instead, this happened:

error[E0644]: closure/generator type that references itself
  --> src/bin/cyclic-repro.rs:13:19
   |
13 |     closure_typer(move || {});
   |                   ^^^^^^^^^^ cyclic type of infinite size
   |
   = note: closures cannot capture themselves or take themselves as argument;
           this error may be the result of a recent compiler bug-fix,
           see issue #46062 <https://github.com/rust-lang/rust/issues/46062>
           for more information

It compiles successfully with the preceding nightly, cargo +nightly-2022-11-04 check, and stable 1.65.0.

Meta

rustc --version --verbose:

rustc 1.67.0-nightly (09508489e 2022-11-04)
binary: rustc
commit-hash: 09508489efc223287731fe8abbd2a81bbf7adf8e
commit-date: 2022-11-04
host: x86_64-apple-darwin
release: 1.67.0-nightly
LLVM version: 15.0.4

To be clear, this is the nightly I installed with rustup install nightly-2022-11-05. I assume it's normal for the commit date to be a day earlier, but I haven't specifically noticed that before.

Related

This sounds extremely similar to #97680, but that bug was reported months earlier whereas this one appeared today. My original discovery involved async fn traits too, but I reduced it to an example which contains only a closure.

@rustbot label regression-from-stable-to-nightly A-closures

[compiler-errors]

This was introduced by me in #101834 -- I'll put up a fix soon.