include!() in statement position expects an expression

a.rs

fn main() {
    include!("b.rs")
}

b.rs

fn b() {}

rustc 1.18.0-nightly (2bd4b5c6d 2017-04-23)

error: expected expression, found keyword `fn`
 --> b.rs:1:1
  |
1 | fn b(){}
  | ^^

1. I think you can just put ; after include!(..). The ; doesn't disturb parsing of the item therein.

   The current behavior is that a macro invocation at the start of a statement is considered to be a macro statement if

   • the macro invocation is followed by ;, or
   • the macro invocation uses {} to enclose its arguments.

   Otherwise the macro invocation is considered to be a macro expression, not a macro statement.

   I suppose the behavior is intentional. Otherwise the parser would not do such case analysis on parentheses/brackets/braces.

   Masaki Hara at 2017-04-28 14:13:37

2. Same error message with a semi-colon:

   fn main() {
       include!("b.rs");
   }
   

   Simon Sapin at 2017-04-28 14:22:44

3. Or curly braces:

   fn main() {
       include! { "b.rs" }
   }
   

   fn main() {
       include! { "b.rs" };
   }
   

   Simon Sapin at 2017-04-28 14:23:36

4. I was only checking the behavior for another macro. Now I know what you mean. Sorry for bothering you.

   Masaki Hara at 2017-04-28 14:32:08

5. I've hit this bug and it's pretty annoying in my case, since I'll have to resort to using build script.

   Martin Habovštiak at 2018-11-03 09:47:11

6. triage: yep, this is still an issue

   here's a repro in txtar format.

   -- a.rs --
   fn main() {
       include!("b.rs");
   }
   -- b.rs --
   fn b() {}
   

   lolbinarycat at 2024-09-08 23:06:14