error: expected `;`, found `#`
  --> $DIR/multiple-tail-expr-behind-cfg.rs:5:64
   |
LL |     #[cfg(feature = "validation")]
   |     ------------------------------ only `;` terminated statements or tail expressions are allowed after this attribute
LL |     [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>()
   |                                                                ^ expected `;` here
LL |     #[cfg(not(feature = "validation"))]
   |     - unexpected token
   |
help: add `;` here
   |
LL |     [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>();
   |                                                                +
help: alternatively, consider surrounding the expression with a block
   |
LL |     { [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>() }
   |     +                                                             +
help: it seems like you are trying to provide different expressions depending on `cfg`, consider using `if cfg!(..)`
   |
LL ~     if cfg!(feature = "validation") {
LL ~         [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>()
LL ~     } else if cfg!(not(feature = "validation")) {
LL ~         String::new()
LL +     }
   |

error: expected `;`, found `#`
  --> $DIR/multiple-tail-expr-behind-cfg.rs:12:64
   |
LL |     #[attr]
   |     ------- only `;` terminated statements or tail expressions are allowed after this attribute
LL |     [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>()
   |                                                                ^ expected `;` here
LL |     #[attr]
   |     - unexpected token
   |
help: add `;` here
   |
LL |     [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>();
   |                                                                +
help: alternatively, consider surrounding the expression with a block
   |
LL |     { [1, 2, 3].iter().map(|c| c.to_string()).collect::<String>() }
   |     +                                                             +

error: cannot find attribute `attr` in this scope
  --> $DIR/multiple-tail-expr-behind-cfg.rs:13:7
   |
LL |     #[attr]
   |       ^^^^

error: aborting due to 3 previous errors