On latest nightly (`1.51.0-nightly (2021-01-14 e38fb306b7f5e65cca34)`) started panicing with `internal error: entered unreachable code` message. MRE: ```rust #[macro_use] macro_rules! req_future { ($v:vis) => { #[pin_project::pin_project] $v struct Send { #[pin] inner: () } }; } req_future! { pub } ``` [(play)](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=9601efe2e637f136294b95bc8db75691)