Static rustc_lint::builtin::INCOMPLETE_INCLUDE

source ·
pub static INCOMPLETE_INCLUDE: &'static Lint
Expand description

The incomplete_include lint detects the use of the include! macro with a file that contains more than one expression.


fn main() {

where the file foo.txt contains:



error: include macro expected single expression in source
 --> foo.txt:1:14
1 | println!("1");
  |              ^
  = note: `#[deny(incomplete_include)]` on by default


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.