pub static INCOMPLETE_INCLUDE: &Lint
Expand description
The incomplete_include
lint detects the use of the include!
macro with a file that contains more than one expression.
§Example
fn main() {
include!("foo.txt");
}
where the file foo.txt
contains:
println!("hi!");
produces:
error: include macro expected single expression in source
--> foo.txt:1:14
|
1 | println!("1");
| ^
|
= note: `#[deny(incomplete_include)]` on by default
§Explanation
The include!
macro is currently only intended to be used to
include a single expression or multiple items. Historically it
would ignore any contents after the first expression, but that can be
confusing. In the example above, the println!
expression ends just
before the semicolon, making the semicolon “extra” information that is
ignored. Perhaps even more surprising, if the included file had
multiple print statements, the subsequent ones would be ignored!
One workaround is to place the contents in braces to create a block expression. Also consider alternatives, like using functions to encapsulate the expressions, or use proc-macros.
This is a lint instead of a hard error because existing projects were
found to hit this error. To be cautious, it is a lint for now. The
future semantics of the include!
macro are also uncertain, see
issue #35560.