compile async await function error

[Brooooooklyn]

Error message:
error: internal compiler error: librustc/infer/region_constraints/mod.rs:659: cannot relate bound region: ReLateBound(DebruijnIndex(1), BrAnon(2)) <= '_#0r

Backtrace:

thread 'main' panicked at 'Box<Any>', librustc_errors/lib.rs:525:9
query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `impl std::future::Future: std::marker::Send`
#1 [typeck_tables_of] processing `main`
#2 [typeck_tables_of] processing `main::{{closure}}`
#3 [type_of] processing `main::{{closure}}`
end of query stack
error: aborting due to previous error

[paracat]

while not exactly the same, i have created a commit for the project reflow that produces a compiler error involving bound region and DebruijnIndex

https://github.com/paracat/reflow/commit/a82b57ce5ab0fcfaca8a82dade25733a6299fdf6

It happened when I'm trying to replace &mut TcpStream with AsyncRead

the commit that comes before this one compiles fine. this should make it easier for the Rust team to locate the error

this is probably related to #55809
with some minor changes i can produce that error

[cramertj]

Closing as duplicate of #57084.