error: cannot concatenate a byte string literal --> $DIR/concat.rs:2:13 | LL | concat!(b'f'); | ^^^^ error: cannot concatenate a byte string literal --> $DIR/concat.rs:3:13 | LL | concat!(b"foo"); | ^^^^^^ error: expected a literal --> $DIR/concat.rs:4:13 | LL | concat!(foo); | ^^^ | = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()` error: expected a literal --> $DIR/concat.rs:5:13 | LL | concat!(foo()); | ^^^^^ | = note: only literals (like `"foo"`, `-42` and `3.14`) can be passed to `concat!()` error: aborting due to 4 previous errors