1error: expected string literal 2 --> tests/ui/concat-display.rs:8:17 3 | 48 | #[error(concat!("invalid ", $what))] 5 | ^^^^^^ 6... 713 | error_type!(Error, "foo"); 8 | -------------------------- in this macro invocation 9 | 10 = note: this error originates in the macro `error_type` (in Nightly builds, run with -Z macro-backtrace for more info) 11