Anonymous bound region BrAnon(0) in return but not args #47511
Description
Looks just like #43567. Mentioning @petrochenkov and @eddyb who were involved in that issue. The following code compiles with 1.21.0 but ICE as of 1.22.0.
fn f(_: X) -> X { unimplemented!() } type X<'a> = <&'a () as Trait>::Value; trait Trait { type Value; } impl<'a> Trait for &'a () { type Value = (); } fn main() {}error: internal compiler error: librustc_typeck/astconv.rs:1212: anonymous bound region BrAnon(0) in return but not args --> src/main.rs:1:15 | 1 | fn f(_: X) -> X { | ^ note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.25.0-nightly (da569fa9d 2018-01-16) running on x86_64-unknown-linux-gnu