error[E0308]: mismatched types `expected fn pointer, found fn item`

Code

I tried this code:

pub fn foo(_: &i32, _: &i32) {}
pub const _: [for<'r> fn(&'r i32, &'r i32); 2] = [foo, foo];

I expected to see this happen: compile successfully

Instead, this happened:

error[E0308]: mismatched types
 --> src/lib.rs:3:56
  |
3 | pub const _: [for<'r> fn(&'r i32, &'r i32); 2] = [foo, foo];
  |                                                        ^^^ expected fn pointer, found fn item
  |
  = note: expected fn pointer `for<'r> fn(&'r _, &'r _)`
                found fn item `for<'a, 'b> fn(&'a _, &'b _) {foo}`

For more information about this error, try `rustc --explain E0308`.
error: could not compile `fnitem` (lib) due to 1 previous error

Version it worked on

It most recently worked on: nightly-2024-02-29

Version with regression

searched nightlies: from nightly-2024-02-28 to nightly-2024-03-01
regressed nightly: nightly-2024-03-01
searched commit range: https://github.com/rust-lang/rust/compare/c475e2303b551d726307c646181e0677af1e0069...878c8a2a62d49ca5c454547ad67290a1df746cb5
regressed commit: https://github.com/rust-lang/rust/commit/878c8a2a62d49ca5c454547ad67290a1df746cb5 cc @spastorino

cargo bisect-rustc --start=2024-02-28 --end=2024-03-01

@rustbot modify labels: +regression-from-stable-to-nightly -regression-untriaged

Reproduce the failure from src/lib.rs using the shown Rust code, then inspect the regressed commit in the provided comparison range. Use cargo bisect-rustc --start=2024-02-28 --end=2024-03-01 if needed to confirm the boundary. Done means the example compiles again without the E0308 error.